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https://starbeamrainbowlabs.com/blog/article.php?article=posts%2F266-TeleConsole-NuGet.html
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## TeleConsole Client is available on NuGet!
(Above: Some cool-looking circuits that feature on the NuGet website)
Hey! After a large amount of research, I've finally figured out how to create a simple NuGet package. Since I ended up using TeleConsole in a recent ACW and it doesn't have any dependencies (making packaging easier!), I decided to use it to test the system.
I think it's turned out rather well actually - you can find it on NuGet here.
Since it's been such a complicated process, rather than talking about TeleConsole itself, I'd like to give a sort-of tutorial on how I did it instead (if you'd like to read more about TeleConsole, I posted about it when I first released it here).
To start with, you'll need to install NuGet. Once done, the next step is to create a .nuspec file for your project. It goes in the same directory as the .csproj file for the project you want to publish on NuGet. I haven't yet figured out how to reference another project in the same solution and have it work with NuGet, but I should imagine it's mostly automatic. Here's the .nuspec file for TeleConsole:
<?xml version="1.0"?>
<package>
<id>TeleConsoleClient</id>
<version>0.3</version>
<title>$title$</title>
<authors>Starbeamrainbowlabs</authors>
<owners>Starbeamrainbowlabs</owners>
<projectUrl>https://gitlab.com/sbrl/TeleConsole/</projectUrl>
<iconUrl>https://gitlab.com/sbrl/TeleConsole/blob/master/logo.png?raw=true</iconUrl>
<description>$description$</description>
<releaseNotes>Initial nuget release.</releaseNotes>
<tags>Debugging Networking Console Remote</tags>
</package>
As you can see, it's actually a fairly simple format - based on XML of course, since C♯ seems to love it for some reason. The bits in \$ signs are special - they are references to the corresponding values in the .csproj file. You can do it for <version> too - but I was experiencing issues with it not picking this up correctly, so I'm specifying it manually. More information about this can be found on the Microsoft website - links are available at the bottom of this post.
With that done, the next step is to package it into a .nupkg file 0 which is basically just a renamed .zip file with a specific structure. The nuget command-line application has the ability to do this for us - but doesn't work on Linux without an extra argument (thanks to @ArtOfSettling on GitHub for discovering this!):
nuget pack -MsbuildPath /usr/lib/mono/msbuild/15.0/bin/
...Windows users don't need to include the -MsbuildPath /usr/lib/mono/msbuild/15.0/bin/ bit. This command will output a .nupkg` file, which you can then upload to nuget.org here, once you're signed in.
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2020-05-25 14:12:03
|
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https://projecteuclid.org/euclid.rmjm/1440168293
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## Rocky Mountain Journal of Mathematics
### Survey Article: Self-adjoint ordinary differential operators and their spectrum
#### Abstract
We survey the theory of ordinary self-adjoint differential operators in Hilbert space and their spectrum. Such an operator is generated by a symmetric differential expression and a boundary condition. We discuss the very general modern theory of these symmetric expressions which enlarges the class of these expressions by many dimensions and eliminates the smoothness assumptions required in the classical case as given, e.g., in the celebrated books by Coddington and Levinson and Dunford and Schwartz. The boundary conditions are characterized in terms of square-integrable solutions for a real value of the spectral parameter, and this characterization is used to obtain information about the spectrum. Many of these characterizations are quite recent and widely scattered in the literature, some are new. A comprehensive review of the deficiency index (which determines the number of independent boundary conditions required in the singular case) is also given for an expression $M$ and for its powers. Using the modern theory mentioned above, these powers can be constructed without any smoothness conditions on the coefficients.
#### Article information
Source
Rocky Mountain J. Math., Volume 45, Number 3 (2015), 763-886.
Dates
First available in Project Euclid: 21 August 2015
https://projecteuclid.org/euclid.rmjm/1440168293
Digital Object Identifier
doi:10.1216/RMJ-2015-45-3-763
Mathematical Reviews number (MathSciNet)
MR3385967
Zentralblatt MATH identifier
1369.47057
Keywords
#### Citation
Zettl, Anton; Sun, Jiong. Survey Article: Self-adjoint ordinary differential operators and their spectrum. Rocky Mountain J. Math. 45 (2015), no. 3, 763--886. doi:10.1216/RMJ-2015-45-3-763. https://projecteuclid.org/euclid.rmjm/1440168293
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2019-10-23 15:47:16
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https://www.physicsforums.com/threads/fuse-wires.155262/
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# Fuse wires
1. Feb 8, 2007
### Vagrant
1. The problem statement, all variables and given/known data
does the length of the fuse wire influence its cpacity? why?
2. Relevant equations
R=pL/a
3. The attempt at a solution
My teacher said no. I think it should because R depends on L
2. Feb 8, 2007
### Andrew Mason
I think I would agree with your teacher. The fuse capacity (the largest current permitted to flow) depends on the temperature of the fuse wire. At a certain temperature, it melts and stops the current. Off hand, I would say that the temperature depends upon the power density being dissipated in the fuse wire (power / unit volume). The power dissipated is $I^2R = I^2\rho L/A$
Now, the power per unit volume is:
$$P/Vol = P/LA = I^2\rho L/A(LA) = I^2\rho/A^2$$
So it appears to me that the L falls out and the temperature depends entirely upon the cross sectional area of the fuse wire.
AM
3. Feb 8, 2007
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2017-02-22 06:59:31
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https://mathoverflow.net/questions/312509/is-every-prime-greater-than-5-less-than-the-sum-of-the-two-previous-primes
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# Is every prime greater than 5, less than the sum of the two previous primes?
Can one prove by elementary means (such as Paul Erdös' proof of Bertrand's Postulate) that every prime greater than 5 is less than the sum of the two primes immediately preceding it?
• From this, $p_{n+2}\leq \frac{3}{2}p_{n+1}\leq p_{n+1}+\frac{3}{4}p_n$. – Wojowu Oct 10 '18 at 19:11
• Prof. Bernardo Recamán Santos: the answer is YES, essentially this question was the subject matter of this previous question in MO: mathoverflow.net/q/113840/1593 – José Hdz. Stgo. Oct 10 '18 at 19:13
• @Wojowu: El Bachraoui's result was already established by Schur in 1929, see Jose Brox's answer here: mathoverflow.net/questions/289402/… . – Ofir Gorodetsky Oct 10 '18 at 19:16
I am to elaborate a bit on how it is that the answer I left in this previous question implies a positive answer to Mr. Recamán's question.
By elementary means (i.e., without resorting to any complex analysis), in his paper Mémoire sur les nombres premiers (Mémoires de l'Acad. Imp. Sci. de St. Pétersbourg, VII, 1850.), P. L. Chebyshev established that for any $$\varepsilon >\frac{1}{5}$$, there exists an $$n_{\varepsilon}\in \mathbb{N}$$ such that for all $$n\geq n_{\varepsilon}$$,
$$\pi((1+\varepsilon)n)−\pi(n)>0.$$
In particular, taking $$\varepsilon = \frac{1}{4}$$, this implies that, for every sufficiently large $$k \in \mathbb{N}$$, we have that
$$p_{k+2} \leq (1.25)^{2}p_{k} < 2p_{k}$$
and whence, for every sufficiently large $$k \in \mathbb{N}$$, it is certainly the case that
$$p_{k+2} < 2p_{k} < p_{k}+p_{k+1}.$$
By retracing Chebyshev's arguments it is possible to obtain an explicit version of the previous conclusion.
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2020-04-03 18:04:57
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http://community.wolfram.com/groups/-/m/t/1164621
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# [✓] Simple rewrite rule using String function works but shows error?
GROUPS:
I used Matlab/Mathematica during my PhD in 1993 and now trying to learn the fascinating Wolfram Language. So this might be a newby question so bear with me. The below simple expression {"a.del", "b.del", "c.del"} /. s__ -> StringDelete[s, ".del"] generates the expectecd content {"a", "b", "c"} but generates also the following error StringDelete::strse: String or list of strings expected at position 1 in StringDelete[s,.del]. What am I doing wrong? Thanks for your help. Regards Markus
Todd Rowland 1 Vote Your syntax is a little unusual, but it did work. The error message is coming from the rule, which gets evaluated before being applied. It is at the lowest level, the second part of ReplaceAll[string, rule] where the rule has its right hand side StringDelete[s,".del"] and s is just a symbol so it generates that message. But it stays unevaluated, and once it has a valid list of strings instead of s it works.The way I would expect this to be entered would be something like StringDelete[{"a.del", "b.del", "c.del"}, ".del"]
Hans Milton 1 Vote No error message is generated if RuleDelayed is used instead of Rule: In[1]:= {"a.del", "b.del", "c.del"} /. s__ :> StringDelete[s, ".del"] Out[1]= {"a", "b", "c"}
Notice that these also work: In[1]:= StringDelete[".del"] /@ {"a.del","b.del","c.del"} Out[1]= {a,b,c} In[2]:= StringDelete[".del"][{"a.del","b.del","c.del"}] Out[2]= {a,b,c} In[3]:= StringDelete[{"a.del","b.del","c.del"},".del"] Out[3]= {a,b,c}
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2018-05-22 11:32:00
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http://www.w3.org/Math/testsuite/build/mathmlcss/Presentation/CSS/mspace/mspace-02-full.xhtml
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prev ( testsuite > Presentation > CSS > mspace > mspace-02 ) next
Alternatives: (mml file) (full) (simple) (plain) (form) (slideshow)
File:Presentation/CSS/mspace/mspace-02
CVS-ID:
Author:George Chavchanidze, Opera Software ASA
Description:Resize window to ensure that expression below is splitted into several lines. Line breaks should occur after even numbers.
Sample Rendering:
$12\phantom{\rule{0ex}{0ex}}34\phantom{\rule{0ex}{0ex}}56\phantom{\rule{0ex}{0ex}}78\phantom{\rule{0ex}{0ex}}910\phantom{\rule{0ex}{0ex}}11121112\phantom{\rule{0ex}{0ex}}1314\phantom{\rule{0ex}{0ex}}1516\phantom{\rule{0ex}{0ex}}1718\phantom{\rule{0ex}{0ex}}1920\phantom{\rule{0ex}{0ex}}2122\phantom{\rule{0ex}{0ex}}2122\phantom{\rule{0ex}{0ex}}23242526\phantom{\rule{0ex}{0ex}}2728\phantom{\rule{0ex}{0ex}}2930\phantom{\rule{0ex}{0ex}}31323132\phantom{\rule{0ex}{0ex}}3334\phantom{\rule{0ex}{0ex}}3536\phantom{\rule{0ex}{0ex}}3738\phantom{\rule{0ex}{0ex}}3940\phantom{\rule{0ex}{0ex}}4142\phantom{\rule{0ex}{0ex}}4142\phantom{\rule{0ex}{0ex}}4344\phantom{\rule{0ex}{0ex}}4546\phantom{\rule{0ex}{0ex}}4748\phantom{\rule{0ex}{0ex}}4950\phantom{\rule{0ex}{0ex}}5152\phantom{\rule{0ex}{0ex}}5152\phantom{\rule{0ex}{0ex}}5354\phantom{\rule{0ex}{0ex}}5556\phantom{\rule{0ex}{0ex}}5758\phantom{\rule{0ex}{0ex}}5960\phantom{\rule{0ex}{0ex}}6162\phantom{\rule{0ex}{0ex}}6162\phantom{\rule{0ex}{0ex}}6364$
Source Code:
```<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<mrow>
<mn>1</mn>
<mn>2</mn><mspace linebreak="goodbreak"/>
<mn>3</mn>
<mn>4</mn><mspace linebreak="goodbreak"/>
<mn>5</mn>
<mn>6</mn><mspace linebreak="goodbreak"/>
<mn>7</mn>
<mn>8</mn><mspace linebreak="goodbreak"/>
<mn>9</mn>
<mn>10</mn><mspace linebreak="goodbreak"/>
<mn>11</mn>
<mn>12</mn></mrow>
<mrow>
<mn>11</mn>
<mn>12</mn><mspace linebreak="goodbreak"/>
<mn>13</mn>
<mn>14</mn><mspace linebreak="goodbreak"/>
<mn>15</mn>
<mn>16</mn><mspace linebreak="goodbreak"/>
<mn>17</mn>
<mn>18</mn><mspace linebreak="goodbreak"/>
<mn>19</mn>
<mn>20</mn><mspace linebreak="goodbreak"/>
<mn>21</mn>
<mn>22</mn><mspace linebreak="goodbreak"/>
<mn>21</mn>
<mn>22</mn><mspace linebreak="goodbreak"/>
<mn>23</mn>
<mn>24</mn></mrow>
<mrow>
<mn>25</mn>
<mn>26</mn><mspace linebreak="goodbreak"/>
<mn>27</mn>
<mn>28</mn><mspace linebreak="goodbreak"/>
<mn>29</mn>
<mn>30</mn><mspace linebreak="goodbreak"/>
<mn>31</mn>
<mn>32</mn></mrow>
<mrow>
<mn>31</mn>
<mn>32</mn><mspace linebreak="goodbreak"/>
<mn>33</mn>
<mn>34</mn><mspace linebreak="goodbreak"/>
<mn>35</mn>
<mn>36</mn><mspace linebreak="goodbreak"/>
<mn>37</mn>
<mn>38</mn><mspace linebreak="goodbreak"/>
<mn>39</mn>
<mn>40</mn><mspace linebreak="goodbreak"/>
<mn>41</mn>
<mn>42</mn><mspace linebreak="goodbreak"/>
<mn>41</mn>
<mn>42</mn><mspace linebreak="goodbreak"/>
<mn>43</mn>
<mn>44</mn><mspace linebreak="goodbreak"/>
<mn>45</mn>
<mn>46</mn><mspace linebreak="goodbreak"/>
<mn>47</mn>
<mn>48</mn><mspace linebreak="goodbreak"/>
<mn>49</mn>
<mn>50</mn><mspace linebreak="goodbreak"/>
<mn>51</mn>
<mn>52</mn><mspace linebreak="goodbreak"/>
<mn>51</mn>
<mn>52</mn><mspace linebreak="goodbreak"/>
<mn>53</mn>
<mn>54</mn><mspace linebreak="goodbreak"/>
<mn>55</mn>
<mn>56</mn><mspace linebreak="goodbreak"/>
<mn>57</mn>
<mn>58</mn><mspace linebreak="goodbreak"/>
<mn>59</mn>
<mn>60</mn><mspace linebreak="goodbreak"/>
<mn>61</mn>
<mn>62</mn><mspace linebreak="goodbreak"/>
<mn>61</mn>
<mn>62</mn><mspace linebreak="goodbreak"/>
<mn>63</mn>
<mn>64</mn></mrow>
[/itex]```
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2015-04-18 05:06:28
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https://www.anl.gov/topic/west-virginia
|
# West Virginia
## Filter Results
• ### Argonne-led collaborations pave the way for a greener tomorrow
Newly funded projects will contribute to innovative, advanced electric vehicle charging.
• ### Argonne set to oversee the Department of Energy’s new vehicle competition for college students
Argonne’s 30 years of success managing advanced vehicle technology competitions for the US Department of Energy has just been underscored with the announcement of The EcoCAR Mobility Challenge.
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2021-12-06 21:16:35
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https://www.physicsforums.com/threads/block-on-wedge-problem.132977/
|
# Block on Wedge Problem
1. Sep 21, 2006
### konichiwa2x
Hi,
A block of mass 'm' slides on a wedge of mass M. The wedge also moves on a smooth frictionless surface. Find the acceleration of the wedge.
I have written down the equations of motion for the wedge and the block but dont know how to proceed further as there are more variables than equations:
a= ax + ay (block)
A = acceleration of wedge
For block:
$$Nsin\theta = m(ax)$$
$$Ncos\theta - mg = m(ay)$$
For wedge:
B is the normal reaction by the ground on Wedge
$$B = mg + Ncos\theta$$
What do I do after this? I think I have to work out a constraint relation here but I am not sure how to do it. Please help.
2. Sep 21, 2006
### Staff: Mentor
First find the horizontal accelerations involved. What's the relationship between A and ax? Your constraint is that the block maintains contact with the wedge. (Hint: View things from the frame of the wedge.)
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2017-10-22 17:38:37
|
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http://math.stackexchange.com/questions/404844/what-is-the-definition-of-restricted-direct-product/404858
|
what is the definition of restricted direct product ?
in an exercise , i'm given a definition of restricted direct product , but it doesn't make sense for me !
they say , the restricted direct product of groups $G_i$ is the set of elements of direct product which are the identity in all but finitely many compontents
i really don't understand what it means to be all but finitely ! i googled and found the same defintion with No clearification !
so , any help by example or explanation ?
-
Do you know what the direct product is? – Brandon Carter May 28 '13 at 15:48
sure ! @BrandonCarter – Maths Lover May 28 '13 at 15:55
I assume you know what the direct product $\times_{i\in I} G_i$ (where $I$ is the indexing set) is. An arbitrary element of it looks like $(g_i)_{i\in I}$.
Now formally what they mean is that such a $(g_i)_{i\in I}$ belongs the restricted direct product iff there exists a finite subset $S\subset I$ such that $g_i=0$ for $i\notin S$ (where $0$ denotes the neutral element in each group).
-
thank you alot ^_^ – Maths Lover May 28 '13 at 16:10
Note first that when we are taking the product of a finite number of groups, then the restricted and normal direct product are the same.
For convenience, let us assume that we have a family of groups indexed by the natural numbers, so we have a $G_i$ for each $i\in\mathbb{N}$.
The usual direct product of the groups $G_i$ can be seen as the set of sequences such that the $i$'th entry of the sequence is an element of $G_i$ (we can also write these as infinite tuples $(g_1,g_2,\dots)$ with each $g_i\in G_i$).
The restricted direct product is then the subgroup of the above direct product where we only take those elements such that for some $N$, the $i$'th entry is $e_i$ whenever $i\geq N$ (I use $e_i$ to denote the identity element of $G_i$). This means that we can see the restricted direct product as the set of finite tuples $(g_1,g_2,\dots,g_n)$ (but where $n$ can be as large as we want) and where we multiply such tuples by first extending the shortest of them by adding $e_i$'s to the end, such that they get the same length, and then multiply them as we usually would do with tuples (and we identify two such tuples if the only difference between them is how many $e_i$'s they end in).
-
thank you :) your answer is so useiful for me :) – Maths Lover May 28 '13 at 16:10
For each $i\geq 0$, let $G_i$ be a group. You have probably already met the infinite direct product $$\prod_{i\geq 0}G_i=\{(g_0,g_1,\ldots)|g_i\in G_i\}$$ where we can choose any $g_i\in G_i$ for the $i$-th position in an element of the product. This set forms a group under pairwise multiplication of each component of two elements.
It turns out that this group has a subgroup called the restricted direct product (or direct sum if the $G_i$ are all abelian) which is the following set $$\tilde{\prod_{i\geq 0}}G_i=\{(g_0,g_1,\ldots)|g_i\in G_i,\exists N\in\mathbb{N},(n>N\Rightarrow g_n=e_n)\}$$ where $e_n\in G_n$ is the identity of the group $G_n$. This is just the group of infinite sequences of elements in the product which are eventually always the identity. You should easily be able to show that this set forms a subgroup of $\prod G_i$.
-
what is $n$ ? , who decide $N$ ? – Maths Lover May 28 '13 at 16:03
Sorry i messed up my indicies, they should have been $n$ not $i$. – Dan Rust May 28 '13 at 16:51
Just thought I'd mention a more general notion of restricted direct product that is used in some contexts (in particular, I'm thinking of adeles). Given any collection of (perhaps topological) groups or rings or algebras or whatever objects $G_i$, and subobjects $H_i\le G_i$, indexed by $i\in I$, then the restricted product of the $\{G_i\}$ with respect to the $\{H_i\}$ is
$$\prod_{i\in I}^{\large\sf restr}G_i=\big\{(g_i)_{i\in I}:g_i\in H_i ~{\rm for~all~but~finitely~many~}i\in I\big\}\le \prod_{i\in I}G_i.$$
We say that "all but finitely many" elements of a collection satisfy a property $P$ if the number of elements that do not satisfy $P$ is finite. That is, all of the elements in the collection satisfy the property outside of only a finite number of exceptions.
In the case of rings or groups, if all of the $H_i$ are just $\{0\}$, the trivial subobject, then we recover the usual understanding of restricted direct product, which is also often (in fact more often) called the "direct sum" and denoted by the big \oplus symbol as $\bigoplus_{i\in I}G_i$.
In number theory for example we take the restricted direct product of the $p$-adic fields ${\bf Q}_p$ over all primes $p$ (with "${\bf Q}_\infty={\bf R}$" the convention for the "infinite prime $p=\infty$") with respect to the subrings ${\bf Z}_p$ for integer primes $p$ to obtain the ring of adeles ${\bf A}_{\bf Q}$.
-
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2015-08-29 09:23:32
|
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https://www.ias.ac.in/listing/articles/jess/123/05
|
• Volume 123, Issue 5
July 2014, pages 923-1195
• Molecular fossils in Cretaceous condensate from western India
The present study reports the biomarker distribution of condensate belonging to the early Cretaceous time frame using gas chromatography-mass spectrometry (GC–MS). The early Cretaceous palaeoenvironment was inscribed into these molecular fossils which reflected the source and conditions of deposition of the condensate. The saturate fraction of the condensate is characterized by normal alkanes ranging from 𝑛-C_{9} to 𝑛-C_{29} (CPI-1.13), cycloalkanes and C_{14} and C_{15} sesquiterpanes. The aromatic fraction comprises of naphthalene, phenanthrene, their methylated derivatives and cyclohexylbenzenes. Isohexylalkylnaphthalenes, a product of rearrangement process of terpenoids, is detected in the condensate. Several aromatic sesquiterpenoids and diterpenoids have been recorded. Dihydro-ar-curcumene, cadalene and ionene form the assemblage of sesquiterpenoids which are indicative of higher plant input. Aromatic diterpenoid fraction comprises of simonellite and retene. These compounds are also indicative of higher plants, particularly conifer source which had been a predominant flora during the Cretaceous time.
• Molecular composition and paleobotanical origin of Eocene resin from northeast India
The molecular composition of fossil resins from early to middle Eocene coal from northeast India, has been analyzed for the first time to infer their paleobotanical source. The soluble component of fossil resin was analyzed using gas chromatography–mass spectrometry (GC–MS). The resin extracts are composed of cadalene-based C_{15} sesquiterpenoids and diagenetically altered triterpenoids. The macromolecular composition was investigated using pyrolysis gas chromatography-mass spectrometry (Py-GC–MS) and Fourier transform infrared (FTIR) spectroscopy. The major pyrolysis products are C_{15} bicyclic sesquiterpenoids, alkylated naphthalenes, benzenes and a series of C_{17}–C_{34} 𝑛-alkene-𝑛-alkane pairs. Spectroscopic analysis revealed the dominance of aliphatic components. The presence of cadalene-based sequiterpenoids confirms the resin to be Class II or dammar resin, derived from angiosperms of Dipterocarpaceae family. These sesquiterpenoids are often detected in many SE Asian fluvio-deltaic oils. Dipterocarpaceae are characteristic of warm tropical climate suggesting the prevalence of such climate during early Eocene in northeast India.
• Granite-hosted molybdenite mineralization from Archean Bundelkhand cratonmolybdenite characterization, host rock mineralogy, petrology, and fluid inclusion characteristics of Mo-bearing quartz
The dominantly high-K, moderate to high SiO2 containing, variably fractionated, volcanic-arc granitoids (± sheared) from parts of Bundelkhand craton, northcentral India are observed to contain molybdenite (Mo) in widely separated 23 locations in the form of specks, pockets, clots and stringers along with quartz ± pyrite ± arsenopyrite ± chalcopyrite ± bornite ± covellite ± galena ± sphalerite and in invisible form as well. The molybdenite mineralization is predominantly associated with Bundelkhand Tectonic Zone, Raksa Shear Zone, and localized shear zones. The incidence of molybdenite is also observed within sheared quartz and tonalite–trondhjemite–granodiorite (TTG) gneisses. The fluid inclusion data show the presence of bi-phase (H2O–CO2), hypersaline and moderate temperature (100°–300°C) primary stretched fluid inclusions suggesting a possible hydrothermal origin for the Mo-bearing quartz occurring within variably deformed different granitoids variants of Archean Bundelkhand craton.
• Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex
The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, crosscutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.
• Rb–Sr and Sm–Nd isotope systematics and geochemical studies on metavolcanic rocks from Peddavura greenstone belt: Evidence for presence of Mesoarchean continental crust in easternmost part of Dharwar Craton, India
Linear, north–south trending Peddavura greenstone belt occurs in easternmost part of the Dharwar Craton. It consists of pillowed basalts, basaltic andesites, andesites (BBA) and rhyolites interlayered with ferruginous chert that were formed under submarine condition. Rhyolites were divided into type-I and II based on their REE abundances and HREE fractionation. Rb–Sr and Sm–Nd isotope studies were carried out on the rock types to understand the evolution of the Dharwar Craton. Due to source heterogeneity Sm–Nd isotope system has not yielded any precise age. Rb–Sr whole-rock isochron age of 2551 ± 19 (MSWD = 1.16) Ma for BBA group could represent time of seafloor metamorphism after the formation of basaltic rocks. Magmas representing BBA group of samples do not show evidence for crustal contamination while magmas representing type-II rhyolites had undergone variable extents of assimilation of Mesoarchean continental crust (< 3.3 Ga) as evident from their initial 𝜀Nd isotope values. Trace element and Nd isotope characteristics of type I rhyolites are consistent with model of generation of their magmas by partial melting of mixed sources consisting of basalt and oceanic sediments with continental crustal components. Thus this study shows evidence for presence of Mesoarchean continental crust in Peddavura area in eastern part of Dharwar Craton.
• Earthquake source characteristics along the arcuate Himalayan belt: Geodynamic implications
The occurrences of moderate to large magnitude earthquakes and associated subsurface geological processes were critically examined in the backdrop of Indian plate obliquity, stress obliquity, topography, and the late Tertiary regional tectonics for understanding the evolving dynamics and kinematics in the central part of the Himalayas. The higher topographic areas are likely associated with the zones of depressions, and the lower topographic areas are found around the ridges located in the frontal part of the orogen. A positive correlation between plate and stress obliquities is established for this diffuse plate boundary. We propose that the zone of sharp bending of the descending Indian lithosphere is the nodal area of major stress accumulation which is released occasionally in form of earthquakes. The lateral geometry of the Himalayas shows clusters of seismicity at an angle of ∼20° from the centre part of the arc. Such spatial distribution is interpreted in terms of compression across the arc and extension parallel to the arc. This biaxial deformation results in the development of dilational shear fractures, observed along the orogenic belt, at an angle of ∼20° from the principal compressive stress axis.
• Hydrogeochemical assessment of groundwater in Kashmir Valley, India
Groundwater samples (𝑛 = 163) were collected across Kashmir Valley in 2010 to assess the hydrogeochemistry of the groundwater in shallow and deep aquifers and its suitability for domestic, agriculture, horticulture, and livestock purposes. The groundwater is generally alkaline in nature. The electrical conductivity (EC) which is an index to represent the total concentration of soluble salts in water was used to measure the salinity hazard to crops as it reflects the TDS in groundwater ranging from 97 to 1385 𝜇S/cm, except one well in Sopore. The average concentration of major ions was higher in shallow aquifers than in deeper aquifers. In general, Ca2+ is the dominant cation and HCO$^{−}_{3}$ the dominant anion. Ca–HCO3, Mg–HCO3, Ca–Mg–HCO3, Na–HCO3 were the dominant hydrogeochemical facies. High concentration of HCO3 and pH less than 8.8 clearly indicated that intense chemical weathering processes have taken place in the study area. The groundwater flow pattern in the area follows the local surface topography which not only modifies the hydrogeochemical facies but also controls their distribution. The groundwater in valley flows into four directions, i.e., SW–NE, NE–W, SE–NW and SE–NE directions. The results suggest that carbonate dissolution is the dominant source of major ions followed by silicate weathering and ion-exchange processes. The concentrations of all the major ions determined in the present study are within the permissible limits ofWHO and BIS standards. The results of Total Hardness, SAR, Na%, Kelly Index, USDA classification, Magnesium absorption ratio, residual sodium carbonate, and PI suggested that groundwater is good for drinking, livestock, and irrigation purposes.
• Observed intraseasonal and seasonal variability of the West India Coastal Current on the continental slope
We present current data from acoustic Doppler current profilers (ADCPs) moored on the continental slope off the west coast of India. The data were collected at four locations (roughly at Kanyakumari, Kollam, Goa, and Mumbai) extending from ∼7° to ∼20° N during 2008–2012. The observations show that a seasonal cycle, including an annual cycle, is present in the West India Coastal Current (WICC); this seasonal cycle, which strengthens northward, shows considerable interannual variability and is not as strongly correlated along the coast as in climatologies based on ship drifts or the altimeter. The alongshore decorrelation of theWICC is much stronger at intraseasonal periods, which are evident during the winter monsoon all along the coast. This intraseasonal variability is stronger in the south. A striking feature of the WICC is upward phase propagation, which implies an undercurrent whose depth becomes shallower as the season progresses. There are also instances when the phase propagates downward. At the two southern mooring locations off Kollam and Kanyakumari, the cross-shore current, which is usually associated with eddy-like circulations, is comparable to the alongshore current on occasions. A comparison with data from the OSCAR (Ocean Surface Currents Analyses Real-time) data product shows not only similarities, but also significant differences, particularly in the phase. One possible reason for this phase mismatch between the ADCP current at 48 m and the OSCAR current, which represents the current in the 0–30 m depth range, is the vertical phase propagation. Current products based on Ocean General Circulation Models like ECCO2 (Estimating the Circulation and Climate of the Ocean, Phase II) and GODAS (Global Ocean Data Assimilation System) show a weaker correlation with the ADCP current, and ECCO2 does capture some of the observed variability.
• An assessment of wind forcing impact on a spectral wave model for the Indian Ocean
The focus of the present study is the assessment of the impact of wind forcing on the spectral wave model MIKE 21 SW in the Indian Ocean region. Three different wind fields, namely the ECMWF analyzed winds, the ECMWF blended winds, and the NCEP blended winds have been used to drive the model. The wave model results have been compared with in-situ observations and satellite altimeter data. This study also evaluated the performance of the wind products during local phenomenon like sea breeze, since it has a significant impact on the wave prediction in the Indian coastal region. Hence we explored the possibility of studying the impact of diurnal variation of winds on coastal waves using different wind fields. An analysis of the model performance has also been made during high wind conditions with the inference that blended winds generate more realistic wave fields in the high wind conditions and are able to produce the growth and decay of waves more realistically.
• Eddy covariance based methane flux in Sundarbans mangroves, India
We report the initial results of the methane flux measured using eddy covariance method during summer months from the world’s largest mangrove ecosystem, Sundarbans of India. Mangrove ecosystems are known sources for methane (CH4) having very high global warming potential. In order to quantify the methane flux in mangroves, an eddy covariance flux tower was recently erected in the largest unpolluted and undisturbed mangrove ecosystem in Sundarbans (India). The tower is equipped with eddy covariance flux tower instruments to continuously measure methane fluxes besides the mass and energy fluxes. This paper presents the preliminary results of methane flux variations during summer months (i.e., April and May 2012) in Sundarbans mangrove ecosystem. The mean concentrations of CH4 emission over the study period was 1682 ± 956 ppb. The measured CH4 fluxes computed from eddy covariance technique showed that the study area acts as a net source for CH4 with daily mean flux of 150.22 ± 248.87 mg m−2 day−1. The methane emission as well as its flux showed very high variability diurnally. Though the environmental conditions controlling methane emission is not yet fully understood, an attempt has been made in the present study to analyse the relationships of methane efflux with tidal activity. This present study is part of Indian Space Research Organisation–Geosphere Biosphere Program (ISRO–GBP) initiative under ‘National Carbon Project’.
• Sediment grain size and hydrodynamics in Mediterranean coastal lagoons: Integrated classification of abiotic parameters
Integrated classification maps were produced by combining sediment grain-size and hydrological data (water renewal time, WRT) from two Mediterranean lagoons, Lesina (LL) and Varano (LV), Italy. The geophysical characteristics of the two basins, derived from detailed bathymetric charts, are quite distinct: ∼30% of LL (mean depth ∼1 m) but only 3% of LV (mean depth ∼3 m) is shallower than 1 m. The sediments of both lagoons are mainly composed of mud (∼80%). A detailed multivariate analysis of grainsize data by EntropyMax classified the lagoon beds of LL and LV into five sedimentary facies. WRT data, computed by a hydrodynamic model, indicated different hydrological conditions in the two lagoons: LL showed a sharp west–east gradient, with a basin-wide average of ∼190 days, whilst LV showed a fairly uniform distribution and a higher basin-wide average (∼260 days). The distribution of sedimentary facies and water renewal times were combined in a composite map representing the distribution of environmental patterns. The approach outlined in this study can be used to improve zonation schemes by providing a hydromorphological perspective on transitional and coastal environments.
• Influence of soil moisture content on surface albedo and soil thermal parameters at a tropical station
Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured during April 2010 to March 2011 at a tropical station, viz., Astronomical Observatory, Thiruvananthapuram, Kerala, India (76° 59’E longitude and 8°29’N latitude). The monthly, seasonal and seasonal mean diurnal variation of soil moisture content is analyzed in detail and is correlated with the rainfall measured at the same site during the period of study. The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also investigated. Surface albedo is found to fall exponentially with increase in soil moisture content. Soil thermal diffusivity and soil thermal conductivity are also estimated from the subsoil temperature profile. Log normal dependence of thermal diffusivity and power law dependence of thermal conductivity on soil moisture content are confirmed.
• Impact of monsoon rainfall on the total food grain yield over India
The study focuses on understanding the variations of precipitation during summer monsoon season and its impact on Kharif and Rabi foodgrain yield over India. Total foodgrain yield over India during Kharif (summer) season is directly affected by variations in the summer monsoon precipitation (June–September). An increase (decrease) in rainfall is generally associated with an increase (decrease) in foodgrain yield. A similar correspondence during the Rabi (winter) foodgrain yield is not evident. The Rabi crop is not directly affected by variations in the post-monsoon precipitation (October–December) alone, also the summer season precipitation influences the Rabi crop through water and soil moisture availability over many parts of India. Though the reduction of rainfall activity during the entire summer monsoon season leads to reduction in crop yields, the occurrence of prolonged rainfall breaks also causes adverse effect on the crop growth resulting in reduced crop yields.
• Study of seasonal climatology and interannual variability over India and its subregions using a regional climate model (RegCM3)
The temporal and spatial variability of the various meteorological parameters over India and its different subregions is high. The Indian subcontinent is surrounded by the complex Himalayan topography in north and the vast oceans in the east, west and south. Such distributions have dominant influence over its climate and thus make the study more complex and challenging. In the present study, the climatology and interannual variability of basic meteorological fields over India and its six homogeneous monsoon subregions (as defined by Indian Institute of Tropical Meteorology (IITM) for all the four meteorological seasons) are analysed using the Regional Climate Model Version 3 (RegCM3). A 22-year (1980–2001) simulation with RegCM3 is carried out to develop such understanding. The National Centre for Environmental Prediction/National Centre for Atmospheric Research, US (NCEP-NCAR) reanalysis 2 (NNRP2) is used as the initial and lateral boundary conditions. The main seasonal features and their variability are represented in model simulation. The temporal variation of precipitation, i.e., the mean annual cycle, is captured over complete India and its homogenous monsoon subregions. The model captured the contribution of seasonal precipitation to the total annual precipitation over India. The model showed variation in the precipitation contribution for some subregions to the total and seasonal precipitation over India. The correlation coefficient (CC) and difference between the coefficient of variation between model fields and the corresponding observations in percentage (COV) is calculated and compared. In most of the cases, the model could represent the magnitude but not the variability. The model processes are found to be more important than in the corresponding observations defining the variability. The model performs quite well over India in capturing the climatology and the meteorological process. The model shows good skills over the relevant subregions during a season.
• Location specific forecasting of maximum and minimum temperatures over India by using the statistical bias corrected output of global forecasting system
The output from Global Forecasting System (GFS) T574L64 operational at India Meteorological Department (IMD), New Delhi is used for obtaining location specific quantitative forecast of maximum and minimum temperatures over India in the medium range time scale. In this study, a statistical bias correction algorithm has been introduced to reduce the systematic bias in the 24–120 hour GFS model location specific forecast of maximum and minimum temperatures for 98 selected synoptic stations, representing different geographical regions of India. The statistical bias correction algorithm used for minimizing the bias of the next forecast is Decaying Weighted Mean (DWM), as it is suitable for small samples. The main objective of this study is to evaluate the skill of Direct Model Output (DMO) and Bias Corrected (BC) GFS for location specific forecast of maximum and minimum temperatures over India. The performance skill of 24–120 hour DMO and BC forecast of GFS model is evaluated for all the 98 synoptic stations during summer (May–August 2012) and winter (November 2012–February 2013) seasons using different statistical evaluation skill measures. The magnitude of Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE) for BC GFS forecast is lower than DMO during both summer and winter seasons. The BC GFS forecasts have higher skill score as compared to GFS DMO over most of the stations in all day-1 to day-5 forecasts during both summer and winter seasons. It is concluded from the study that the skill of GFS statistical BC forecast improves over the GFS DMO remarkably and hence can be used as an operational weather forecasting system for location specific forecast over India.
• # Journal of Earth System Science
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2019-10-15 20:01:25
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# On Uninformative Optimal Policies in Adaptive LQR with Unknown B-Matrix
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### Abstract
This paper presents local asymptotic minimax regret lower bounds for adaptive Linear Quadratic Regulators (LQR). We consider affinely parametrized $$B$$-matrices and known $$A$$-matrices and aim to understand when logarithmic regret is impossible even in the presence of structural side information. After defining the intrinsic notion of an uninformative optimal policy in terms of a singularity condition for Fisher information we obtain local minimax regret lower bounds for such uninformative instances of LQR by appealing to van Trees' inequality (Bayesian Cram\'er-Rao) and a representation of regret in terms of a quadratic form (Bellman error). It is shown that if the parametrization induces an uninformative optimal policy, logarithmic regret is impossible and the rate is at least order square root in the time horizon. We explicitly characterize the notion of an uninformative optimal policy in terms of the nullspaces of system-theoretic quantities and the particular instance parametrization.
### Author and article information
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18 November 2020
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2011.09288
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2021-04-12 07:22:36
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https://space.stackexchange.com/questions/34767/could-a-cubesat-be-self-propelled-to-the-moon-from-leo
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# Could a cubesat be self propelled to the moon from LEO?
Is it possible with current technologies to propel a cubesat, which is launched from Earth, to the moon?
If current propulsion systems are able to do so, how do I continue the research in this topic and what calculations do I have to do to to continue?
• It may be helpful to change the title to reflect your question better. Do you mean for the cubesat to be carried by a larger rocket, or for the cubesat to propel itself? If the latter, would it be from low Earth orbit? You've gotten answers that address both possibilities but clearing the title up would help future viewers of this question. – ben Mar 13 at 4:11
Let's look at some possible examples, building on @ben's answer and @ Knudsen's answer.
We know that the MarCo cubesats were able to navigate from Earth to Mars, with
• attitude control via reaction wheels and cold gas thrusters
• science data and image collection
• communication directly with Earth via a unique pop-up flat high gain antenna
• 70W of solar power at 1 AU via two deployable solar panels plus battery storage
• standard 6U form factor
So let's adopt the MarCo design. They didn't provide their own propulsion, so let's add a propulsion system directly to MarCo's 6U, 14kg initial configuration, and call it 10U and 22 kg. The extra 4U volume is mostly for engines and extra propellant, the extra 8 kg mass budget is for engines and additional solar panels for more electric power, especially out near Mars and a whole bunch more propellant!
Looking for at least apparently existing cubesat electric propulsion systems that you could put in a 3U cubesat today (or soon), the first one that came up in my search is the IFM Nano Thruster for CubeSats. I am sure thee are other options out there, let's just use this as an example. According to that page:
Dynamic thrust range 10 μN to 0.5 mN
Nominal thrust 350 μN
Specific impulse 2,000 to 5000 s
Propellant mass 250 g
Total impulse more than 5,000 Ns
Power at nominal thrust 35 W incl. neutralizer
Our cubesat will have enough electric power for two engines at 1 AU, since we've expanded the form factor by 4 U and mass budget by 8 kg will allow for larger solar panels.
Our two off-the-shelf engines with 250 g propellant tanks each can provide a total impulse of as much as 10,000 Newton seconds. With an average mass of about 20 kg, that only provides a delta-v of 500 m/s. But how much do we need?
Luckily there's an existing mission that addresses this already! Answers to Going from LEO to lunar using only low-thrust ion propulsion - can it be done? say that the SMART-1 mission has done this already!
According to that article the propulsion system used to provide a trajectory from GTO to the Moon (crash landing) demonstrated a total delta-v of about 3,900 m/s.
Luckily we'd added 8kg to our mass budget, so if we'd added an extra 5 kg of propellant we'd have a total impulse of 100,000 Newton seconds and a delta-v of about 5,000 m/s.
Conclusion:
A back-of-the-envelope calculation starting with a MarCo-like cubesat with demonstrated capability of going from Earth all the way to Mars, augmented from 6U 14 kg to 10U 22 kg with two existing engine designs and another 5 kg of propellant, we can get from GTO to the Moon using solar-electric propulsion.
The extra delta-v allows for maneuvering near the Moon and doing a bit of sight-seeing and selfie-taking.
Alternatively you could use the extra delta-v to boost yourself from LEO to GTO, allowing for a more standard cubesat deployment option as long as the inclination were not too high. That would probably need another few kg of propellant, so it's marginal. Best way to proceed would be to piggy-back on one of the many existing launches to GTO in a similar way to how the MarCo's piggy-backed to the transfer orbit to Mars.
Source: MarCO: Mars Cube One
below: Source: Emily Lakdawalla's Planetary Society blogpost MarCO: CubeSats to Mars!
MARCO SPACECRAFT: Engineer Joel Steinkraus stands with both of the Mars Cube One (MarCO) spacecraft at NASA's Jet Propulsion Laboratory. The one on the left is folded up the way it will be stowed on its rocket; the one on the right has its solar panels fully deployed, along with its high-gain antenna on top.
An alternative, future propulsion system with even higher Isp and therefore needing less propellant mass:
An encouraging video:
• Excellent answer! I did not want to venture into the math but my guess was the required size would be much larger than 10U. Turns out this is a really attainable mission for a group with a (relatively) small grant. – ben Mar 13 at 4:07
• @ben I think it's at least a few million \$US just to buy all of the parts, put them together, and do some basic tests. Maybe you can save some if you build every component from scratch, but that's not going to be so reliable. There's also significant expense in making them spaceworthy and to do all of the logistics of preparing them for launch, obtaining all of the permission. This doesn't include an actual launch, which for such a large cubesat would require special arrangements. If that's still considered (relatively) small, then you're good to go! – uhoh Mar 13 at 4:11
• Oh no doubt this is a subjective statement. No one is doing this in their garage for instance. It's just cool to think that we are at a point where for instance a small university research group could actually attain enough funding to send a mission to the moon. Of course this would also require hitching a ride (like you say, a bit complex with the size) or securing NASA or equivalent support for launch. It's cool to watch space become more accessible. Even if they are baby steps they are steps in the right direction. – ben Mar 13 at 4:25
• @ben absolutely! This answer is base on a proven design. No doubt if you started here and went back to the drawing board you cold find lower cost solutions. Comms would be easier to implement since the Moon is a lot closer than Mars. Remember that the radiation is higher than in LEO, so all of the electronics will have to be somewhat radiation resistant and tolerant to regular faults and crashes, but that's doable with redundancy which is probably cheaper than top-of-the-line rad-hard electronics. The triple-junction solar cells are really pricey, lower efficiency silicon will lower cost. – uhoh Mar 13 at 4:38
• "hey alexa, what's the energy density of pu-239" – tedder42 Mar 13 at 23:28
Very Possible
Cubesats are small - typically the base cube is 10 cm square and under 1.5kg and larger cubesats can be made of combinations of this base size. Much larger spacecraft have been sent to the moon, and I imagine there are any number of possible launchers and propulsion systems to allow this. In fact, multiple groups are currently working on it:
Cubesats have already been to Mars, as part of the InSight lander mission.
Self Propelled
It's not clear from your question if you are asking about a self propelled cubesat, possibly starting at LEO? If so, check this recent paper out. A lot of the necessary equations are explained within. The concept of cubesats with significant propulsion capabilities is newer, but presumably one could add modules containing enough fuel for a cubesat to get itself to the moon.
What Do You Need To Study?
Maybe start with the vis viva equation and the rocket equation and their respective formulations. This is a decent primer on orbital mechanics if you are starting completely from scratch.
• One significant problem is not so much delta-V as radio control. Moon isn't that far so it's not insurmountable, but a good radio to cover a long distance and both receive signal from Earth and transmit it at power receivable on Earth tends to be big and power-hungry. Not much good sending the fanciest satellite if it loses contact and nobody gets to know what it discovered and what is it doing. – SF. Mar 13 at 11:20
• @SF. very true, and something I left out in my answer. The selected answer covers this exact issue in basing a hypothetical design on the MarCo cubesats. – ben Mar 13 at 23:48
Yes, but it has not been done yet.
NASA is currently sending three CubeSat missions I know of to the moon on EM-1 sometime in 2020 (according to current estimates of the SLS timeline). I believe they are all 6U spacecraft. http://exploredeepspace.com/news/the-cubesats-of-slss-em-1/
The three missions are:
All three will use solar-electric propulsion to change orbits. Only LunaH and Lunar IceCube will actually establish orbits around the moon though.
Further study of orbital mechanics will help in evaluating the trade-offs between the delta-v provided by the launch vehicle, solar power systems, and low thrust trajectory optimization.
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2019-06-25 16:20:06
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http://www.dbms-notes.com/2012/02/q-fast-recovery-area-iii.html
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## Pages
### Q&As: Fast Recovery Area (III)
(Q) What types of database files can be stored in the FAST RECOVERY AREA?
• control file, online redo logs, archived redo logs, flashback logs, and RMAN backups
(Q) What two types of files, with respect to their use by the database, are kept in the FAST RECOVERY AREA?
• Permanent files – Active files used by the database instance (control file, online redo logs)
• Transient files – backups that may be deleted according to the retention policy
(Q) What happens if the instance cannot write to a multiplexed copy of the control file stored in the fast recovery area?
• The instance fails.
• Failure occurs EVEN if accessibel multiplexed copies are accessible outside the recovery area.
(Q) What is the difference between FLASH RECOVERY AREA and FAST RECOVERY AREA?
• Just the name. FLASH became FAST with 11g
(Q) When configuring the FAST RECOVERY AREA, what happens if you specify DB_RECOVERY_FILE_DEST but DO NOT specify DB_RECOVERY_FILE_DEST_SIZE?
• Specifying DB_RECOVERY_FILE_DEST without specifying DB_RECOVERY_FILE_DEST_SIZE is not allowed.
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2022-05-23 12:23:47
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https://defme.xyz/post/frequentist-vs-bayesian/
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# Who would you rather date Bayes Factor or p-value?
An overview of the differences between Frequentist and Bayesian approaches for hypothesis testing for a population proportion
## Introduction
Code
import numpy as np
import matplotlib.pyplot as plt
from scipy import stats
from statsmodels.stats.proportion import proportion_confint
RANDOM_SEED = 1
plt.xkcd();
def binom_beta(a, b, n, k):
"""
Parameters:
a: alpha
b: beta
n: number of trials
k: number of succeses
"""
x = np.linspace(0,1,100)
# prior values
mean_prior = a/(a+b)
prior = stats.beta.pdf(x=x, a=a, b=b)
likelihood = stats.binom.pmf(k=k, n=n, p=x)
# posterior values
a_new = a + k
b_new = b + n - k
mean_post = a_new / (a_new+b_new)
post = stats.beta.pdf(x=x, a=a_new, b=b_new)
# 95% credible interval
lwr = stats.beta.ppf(q=0.025, a=a_new, b=b_new)
uppr = stats.beta.ppf(q=0.975, a=a_new, b=b_new)
# indeces for plotting the credible interval
indx1 = np.isclose(lwr, x, atol=1e-02).argmax()
indx2 = np.isclose(uppr, x, atol=1e-02).argmax() + 1
print(f"Number of trials: {n}")
print(f"Number of successes: {k}")
print(f"Prior mean: {mean_prior:.2}")
print(f"Posterior mean: {mean_post:.2}")
print(f"95% credible interval: ({lwr:.2}, {uppr:.2})")
plt.figure(figsize=(18, 4))
plt.subplot(131)
plt.plot(x, prior)
plt.axvline(mean_prior, linestyle='--', color='r')
plt.xlabel('P(MTCT)')
plt.ylabel('Probability')
plt.title('Prior Probability')
plt.subplot(132)
plt.plot(x, likelihood)
plt.xlabel('P(MTCT)')
plt.title('Likelihood')
plt.subplot(133)
plt.plot(x, post)
plt.fill_between(x=x[indx1:indx2], y1=post[indx1:indx2],
alpha=0.5, color='red')
plt.axvline(mean_post, linestyle='--', color='r')
plt.xlabel('P(MTCT)')
plt.title('Posterior Probability')
plt.show()
Frequentist vs Bayesian battle is one of the “hot” topics in the statistics world. On the one hand, Bayesian says that p-value can be uninformative and can find statistically significant differences when in fact there are none. On the other hand, Frequentist says that choosing prior probabilities for your hypotheses might be cheating. In this overview I will try to show a simple example of the hypothesis testing for a population proportion using both approaches. However, I will not make any statements like “X approach is awesome, do not use Y approach” and leave the conclusion making to the reader. Most of the calculations will be done “by hand” along with Python implementations, but I will try to keep a balance between going too much into details and skipping some parts.
Alright, let’s begin!
Consider the mother-to-child transmission (MTCT) of HIV (human immunodeficiency virus) ratio1. You want to check whether the probability that an HIV-positive mother can transmit HIV to her baby during pregnancy, childbirth, or breastfeeding is 0.5 or less (say, 0.4). You have collected data from 50 HIV-positive women and their new-born children. 21 children were tested positive for HIV (0.42 ratio). Is there enough evidence to say that the probability of MTCT is less than a random chance given the observed data? (Disclaimer: numbers are made up).
## Frequentist Approach
Let’s start with the Frequentist approach and null hypothesis significance testing (NHST). Under this framework we usually (if not always) set our null hypothesis ($H_0$) value to some constant value, build the desired probability distribution assuming that $H_0$ is true and then find the probability of observed data in the direction of the alternative hypothesis ($H_A$). Direction could be one-sided (less/greater, $<$ / $>$, one-tail test) or two-sided (less or greater, $\neq$, two-tail test). For our example we have:
• $H_0$: the probability of MTCT of HIV is 50%, $P(\text{MTCT})=0.5$;
• $H_A$: the probability of MTCT of HIV is less than 50%, $P(\text{MTCT})<0.5$;
• Significance level $\alpha=5%$
In other words, we build a distribution under the assumption that the probability of MTCT is 0.5 and we want to check if the data we collected provides enough evidence that it comes from the distribution with another probability (which is less than 0.5). The significance level is our threshold value, which is kind of arbitrary, but in most cases is set to 5%. We will reject the null hypothesis if the p-value2 is less than $\alpha$.
In statistical testing, the p-value is the probability of obtaining test results at least as extreme as the results actually observed, under the assumption that the null hypothesis is correct. A very small p-value means that such an extreme observed outcome would be very unlikely under the null hypothesis.
$n=50$, $k=21$
Since our data follows a Binomial distribution we can calculate the probability mass function given the null value.
n = 50
k = 21
h_0 = 1/2
x = np.arange(n+1)
probs = stats.binom.pmf(k=x, n=n, p=h_0)
# temporary array for the plot (p-value)
temp = probs.copy()
temp[x>k] = 0
Code
plt.figure(figsize=(10,4))
plt.bar(x, probs)
plt.bar(x, temp, color='r', label='p-value')
plt.axvline(k+0.5, linestyle='--', color='r')
plt.title(f'PMF under the null hypothesis (p = {h_0})')
plt.ylabel('Probability')
plt.xlabel('Amount of infected children')
plt.legend()
plt.show()
We want to know the probability of obtaining the results as extreme as the results actually observed. Since we had a one-tail test ($<$), the “extreme” results would be obtaining 21 or less HIV infected children (red bars).
$$\scriptsize \text{p-value} = \sum_{i=0}^k P(X_i) = P(0) + P(1) + … + P(21)$$ $$\tiny =\binom{50}{0} \left( \frac{1}{2} \right) ^0 \left( 1 - \frac{1}{2} \right) ^{50-0} + \binom{50}{1}\left( \frac{1}{2} \right) ^1 \left( 1 - \frac{1}{2} \right) ^{50-1}$$ $$\tiny + … + \binom{50}{21} \left( \frac{1}{2} \right) ^{21} \left( 1 - \frac{1}{2} \right) ^{50-21}$$ $$\scriptsize \approx 0.161$$
p_val = stats.binom.cdf(k=k, n=n, p=h_0)
# equivalent
# p_val = stats.binom_test(x=k, n=n, p=h_0, alternative='less')
print(f"p-value = {p_val: .3f}")
p-value = 0.161
p-value equals 0.161 so we failed to reject the null hypothesis, meaning that there is not enough evidence to claim that the probability of MTCT of HIV is less than a random chance (0.5).
### Changing Hypotheses
Here is an interesting phenomenon. We have seen that there is not enough evidence to reject the hypothesis that 21 out of 50 infected children come from a distribution with the probability of success 0.5. What will happen if we change the hypothesis but keep the idea somewhat similar. Is there enough evidence to claim that the population proportion is greater than 0.4?
• $H_0$: the probability of MTCT of HIV is 40%, $P(\text{MTCT})=0.4$;
• $H_A$: the probability of MTCT of HIV is greater than 40%, $P(\text{MTCT})>0.4$;
• $\alpha=5%$
h_0 = 4/10
probs = stats.binom.pmf(k=x, n=n, p=h_0)
temp = probs.copy()
temp[x<k] = 0
Code
plt.figure(figsize=(10,4))
plt.bar(x, probs)
plt.bar(x, temp, color='r', label='p-value')
plt.axvline(k-0.5, linestyle='--', color='r')
plt.title(f'PMF under the null hypothesis (p = {h_0})')
plt.ylabel('Probability')
plt.xlabel('Amount of infected children')
plt.legend()
plt.show()
$$\scriptsize \text{p-value} = \sum_{i=21}^n P(X_i) = P(21) + P(22) + … + P(50)$$ $$\tiny =\binom{50}{21} \left( \frac{4}{10} \right) ^{21} \left( 1 - \frac{4}{10} \right) ^{50-21} + \binom{50}{2} \left( \frac{4}{10} \right) ^{22} \left( 1 - \frac{4}{10} \right) ^{50-22}$$ $$\tiny + … + \binom{50}{50} \left( \frac{4}{10} \right) ^{50} \left( 1 - \frac{4}{10} \right) ^{50-50}$$ $$\scriptsize \approx 0.439$$
p_val = 1 - stats.binom.cdf(k=k-1, n=n, p=h_0)
# equivalent
# p_val = stats.binom_test(x=k, n=n, p=h_0, alternative='greater')
print(f"p-value = {p_val: .3f}")
p-value = 0.439
Now we calculate the binomial pmf function with the probability of success $P(\text{MTCT})=0.4$ and p-value is going to be a sum of probabilities $P(X \geq 21)$. We can see that this value is around 44%, which is much higher than our significance level alpha. Again, we failed to reject the null hypothesis, meaning that there is not enough evidence to claim that the probability of MTCT of HIV is higher than 40%.
We were unable to reject the hypothesis that MTCT ratio is 50%, but at the same time, we were unable to reject the hypothesis that the ratio is 40%. As we can see, NHST is very sensitive to the null hypothesis you choose. Changing the hypotheses (even if the idea behind them stays quite the same) can lead to contradictory results.
### Confidence Intervals
We could also build a Frequentist confidence interval to show our uncertainty about the ratio of MTCT. For the large amount of $n$ in binomial trials, we can say that random variable $X$ follows a normal distribution with the mean $\hat{p}$ and standard error $\frac{\hat{p}(1-\hat{p})}{n}$.
$$X \sim \mathcal{N} \big( \mu = \hat{p}, SE = \frac{\hat{p}(1-\hat{p})}{n} \big)$$
Once we have a normal distribution we can easily calculate 95% CI:
$$(1-\alpha) \text{% CI}: \mu \pm Z_{1-\alpha/2} \cdot SE$$
• $\hat{p} = \frac{k}{n}=0.42$
• $Z_{1-0.05/2} = 1.96$
• $SE = \frac{0.42(1-0.42)}{50} \approx 0.07$
$$95\text{% CI}: (0.28, 0.56)$$
p_hat = k/n
z_score = stats.norm.ppf(0.975)
se = np.sqrt((k/n * (1-k/n))/n)
lwr, uppr = p_hat - z_score*se, p_hat + z_score*se
# equivalent
# proportion_confint(count=k, nobs=n, alpha=0.05, method='normal')
print(f"95% CI for the proportion: ({lwr:.2f}, {uppr:.2f}).")
95% CI for the proportion: (0.28, 0.56).
In other words, we are 95% confident that the true proportion of MTCT lies in the interval $(0.28, 0.56)$. However, we don’t know if our CI has included the true value (it is either 0 or 1). We can also say, that if we would get more samples of the size 50 and calculated the CI for each of them, 95% of these CIs would hold a true value.
### Bayesian Approach
Now it’s Bayesian approach turn. Under this framework, we can specify two distinct hypotheses and check which one is more likely to be true.
• $H_1$: the probability of MTCT of HIV is 50%, $P(\text{MTCT})=0.5$;
• $H_2$: the probability of MTCT of HIV is 40%, $P(\text{MTCT})=0.4$.
We are going to apply Bayes rule to calculate the posterior probability after we observed the data.
$$\scriptsize P(\text{Model}|\text{Data}) = \frac{P(\text{Data|Model}) \cdot P(\text{Model})}{P(\text{Data})}$$
• $P(\text{Data|Model})$ is the likelihood, or probability that the observed data would happen given that model (hypothesis) is true.
• $P(\text{Model})$ is the prior probability of a model (hypothesis).
• $P(\text{Data})$ is the probability of a given data. It is also sometimes referred to as normalizing constant to assure that the posterior probability function sums up to one.
• $P(\text{Model}|\text{Data})$ is the posterior probability of the hypothesis given the observed data.
Assume that we have no prior information about the MTCT, so we believe that both hypotheses have equal chances to be true.
Prior:
$\scriptsize P(H_1)=P(H_2)=\frac{1}{2}$
Note that the prior probability mass function has to sum up to 1.
Likelihood:
• $\tiny P(k = 21 | H_1 \text{ is true}) = \binom{n}{k} \cdot P(H_1)^k \cdot (1-P(H_1))^{n-k}$
$\scriptsize = \binom{50}{21} \cdot 0.5^{21} \cdot (1-0.5)^{50-21}=0.0598$
• $\tiny P(k = 21 | H_2 \text{ is true}) = \binom{n}{k} \cdot P(H_2)^k \cdot \left( 1-P(H_2) \right) ^{n-k}$
$\scriptsize = \binom{50}{21} \cdot 0.4^{21} \cdot (1-0.4)^{50-21}=0.109$
Posterior probabilities:
• $\scriptsize P(H_1 \text{ is true|}k = 21) = \frac{P(k = 21 | H_1 \text{ is true}) \cdot P(H_1)}{P(\text{k = 21})}$
• $\scriptsize P(H_2 \text{ is true|}k = 21) = \frac{P(k = 21 | H_2 \text{ is true}) \cdot P(H_2)}{P(\text{k = 21})}$
$$\tiny P(k=21)=P(k = 21 | H_1 \text{ is true}) \cdot P(H_1) + P(k = 21 | H_2 \text{ is true}) \cdot P(H_2)$$
$$\scriptsize =0.0598 \cdot 0.5 + 0.109 \cdot 0.5 = 0.084$$
• $\scriptsize P(H_1 \text{ is true|}k = 21) = 0.354$
• $\tiny P(H_2 \text{ is true|}k = 21) = 1 - P(H_1 \text{ is true|}k = 21) = 0.646$
As we can see, the probability of the second hypothesis $P(MTCT) = 40%$ equals 64.6%, whereas the probability of the first hypothesis $P(MTCT) = 50%$ equals 35.4%.
If we want to check if there is enough evidence against one of the hypotheses, we can use the Bayes factor3 (which is kind of an analog of the Frequentist’s p-value).
The Bayes factor is a likelihood ratio of the marginal likelihood of two competing hypotheses, usually a null and an alternative. The aim of the Bayes factor is to quantify the support for a model over another, regardless of whether these models are correct.
$$\scriptsize \text{BF}(H_2:H_1)= \frac{\text{Likelihood}_2}{\text{Likelihood}_1}$$ $$\scriptsize = \frac{P(k = 21 | H_2 \text{ is true})}{P(k = 21 | H_1 \text{ is true})} = \frac{\frac{P(H_2 \text{ is true}|k=21) P(k=21)}{P(H_2\text{ is true)}}}{\frac{P(H_1 \text{ is true}|k=21) P(k=21)}{P(H_1\text{ is true)}}}$$ $$\scriptsize = \frac{\frac{P(H_2 \text{ is true}|k=21)}{P(H_1\text{ is true}|k=21)}}{\frac{P(H_2)}{P(H_1)}} = \frac{\text{Posterior Odds}}{\text{Prior Odds}}$$
$$\scriptsize \text{BF}(H_2:H_1)= \frac{\frac{0.646}{0.354}}{\frac{0.5}{0.5}} \approx 1.82$$
To interpret the value we can refer to Harold Jeffreys interpretation table:
Hence we can see there is not enough supporting evidence for $H_2$ (that the MTCT rate is 40%).
prior = {'h_1': .5, 'h_2': .5}
model = {'h_1': .5, 'h_2': .4}
likelihood = {'h_1': stats.binom.pmf(k=k, n=n, p=model['h_1']),
'h_2': stats.binom.pmf(k=k, n=n, p=model['h_2'])}
norm_const = (likelihood['h_1']*prior['h_1'] + likelihood['h_2']*prior['h_2'])
posterior = {'h_1': likelihood['h_1']*prior['h_1'] / norm_const,
'h_2': likelihood['h_2']*prior['h_2'] / norm_const}
bf = (posterior['h_2']/posterior['h_1']) / (prior['h_2']/prior['h_1'])
print(f"Bayes Factor (H2:H1) = {bf:.2f}")
Bayes Factor (H2:H1) = 1.82
Code
plt.figure(figsize=(18, 4))
plt.subplot(131)
plt.bar(x=prior.keys(), height=prior.values())
plt.xlabel('Model')
plt.ylabel('Probability')
plt.title('Prior Probability')
plt.subplot(132)
plt.bar(x=likelihood.keys(), height=likelihood.values())
plt.xlabel('Model')
plt.title('Likelihood')
plt.subplot(133)
plt.bar(x=posterior.keys(), height=posterior.values())
plt.xlabel('Model')
plt.title('Posterior Probability')
plt.show()
### Beta-Binomial Distribution and Credible Intervals
We have specified two distinct hypotheses $H_1$ and $H_2$. But also we could define the whole posterior probability distribution function of an unknown parameter $P(\text{MTCT})$.
Let’s assume that we have no prior information about the probability of HIV transmission and $P(\text{MTCT})$ can take any value on the $[0,1]$ range. Or in other words $P(\text{MTCT})$ follows a uniform distribution $P(\text{MTCT}) \sim \text{unif}(0,1)$. For the reasons, that will not be discussed here, we are going to replace the Uniform distribution with Beta distribution $\text{Beta}(\alpha,\beta)$ with parameters $\alpha=1$, $\beta=1$, $P(\text{MTCT}) \sim \text{Beta}(1,1)$, which is exactly like the uniform. It just makes calculations (and life) easier since Beta and Binomial distribution form a conjugate family4. The likelihood still follows a Binomial distribution.
Now, in order to find the posterior distribution we can just update the values of the Beta distribution:
• $\alpha^* = \alpha + k$
• $\beta^* = \beta + n - k$
Note: I skipped the calculations that explain how $\alpha^*$ and $\beta^*$ were obtained, but you can find them here.5
The expected value of the Beta distribution is:
$$E(x) = \frac{\alpha}{\alpha+\beta}$$
To summarize:
• Prior: $\scriptsize P(\text{MTCT}) \sim \text{Beta}(\alpha=1,\beta=1)$
• Likelihood: $\scriptsize P \big( k = 21 | P(\text{MTCT}) \big) \sim B(n, P(\text{MTCT}))$
$\scriptsize= \binom{n}{k} \cdot P(\text{MTCT})^k \cdot \big( 1-P(\text{MTCT}) \big) ^{n-k}$
• Posterior: $\scriptsize P(\text{MTCT}) \sim \text{Beta}(\alpha^*=\alpha + k,\beta^* = \beta + n - k)$
After we find the posterior distribution we can derive the Bayesian credible interval (CrI) which will tell us the probability of our unknown parameter $P$. Usually it is found as the narrowest interval with the desired area (like 0.95).
# custom function
binom_beta(a=1, b=1, n=n, k=k)
Number of trials: 50
Number of successes: 21
Prior mean: 0.5
Posterior mean: 0.42
95% credible interval: (0.29, 0.56)
What can we tell from these three plots? First, we knew nothing about our parameter $P(\text{MTCT})$, it could be any value from 0 to 1 with the expected value of 0.5 (prior). After we got 21 out of 50 HIV-positive children we could calculate the probability of obtaining such results under each value of $P(\text{MTCT})$ in the $[0,1]$ range (likelihood). And finally, we were able to update our probability distribution function to get the posterior probabilities. We see, that given the data, the expected value for the $P(\text{MTCT})$ is 0.42. The real value of $P(\text{MTCT})$ is in the range $(0.29, 0.56)$ with the probability of 95% (CrI).
The question that could be asked here is what would happen if we chose wrong priors, would we get different results? This might be the case. However, with the relatively large amount of trials, posterior distribution relies more on a likelihood, rather than prior probability distribution so priors don’t have a big weight on the results.
Let’s say that we believe that the probability of mother-to-child transmission is definitely bigger than the random chance (0.5) with the expected value 0.75. We can use parameters $\alpha=15$, $\beta=5$ for this.
binom_beta(a=15, b=5, n=n, k=k)
Number of trials: 50
Number of successes: 21
Prior mean: 0.75
Posterior mean: 0.51
95% credible interval: (0.4, 0.63)
As we can see, posterior distribution has not shifted that much, meaning the priors didn’t have so much weight.
Now imagine that we have 5 times more observations (with the same ratio 0.42):
binom_beta(a=15, b=5, n=n*5, k=k*5)
Number of trials: 250
Number of successes: 105
Prior mean: 0.75
Posterior mean: 0.44
95% credible interval: (0.39, 0.5)
The shape of the posterior distribution looks more like the shape of likelihood and now the credible interval became narrower, meaning that we have decreased uncertainty about the unknown parameter $P(\text{MTCT})$.
## Summary
As I told at the beginning, the purpose of this overview was not to distinguish “the best” approach, but rather look at their differences and pros/cons. The key points of each approach are represented in a table:
Frequentist ApproachBayesian Approach
Doesn’t rely on prior information about the unknownRelies on prior information about the unknown (but prior beliefs become less significant as the sample size increases)
Sensitive to the null hypothesisIs not sensitive to hypotheses
Estimates the degree of uncertainty using confidence intervalsEstimates the degree of uncertainty using credible intervals
Cannot distinguish the probability of a true value in a CI (it is either 0 or 1)Can distinguish the probability of a true value in a CrI
If you would like to learn more about Frequentist and Bayesian approaches here are some resources I personally like:
1. Online book: An Introduction to Bayesian Thinking. A Companion to the Statistics with R Course, Merlise Clyde, Mine Cetinkaya-Rundel, Colin Rundel, David Banks, Christine Chai, Lizzy Huang, 2020. https://statswithr.github.io/book/
2. Online book: An Introduction to Bayesian Data Analysis for Cognitive Science, Bruno Nicenboim, Daniel Schad, and Shravan Vasishth, 2020. https://vasishth.github.io/bayescogsci/book/
3. Coursera specialization: Statistics with R Specialization by Duke University. https://www.coursera.org/specializations/statistics
4. Coursera course: Bayesian Statistics: From Concept to Data Analysis by University of California, Santa Cruz. https://www.coursera.org/learn/bayesian-statistics/
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2021-01-24 18:55:39
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https://math.stackexchange.com/questions/1679323/51-people-enter-a-raffle-with-10-prizes-7-are-pencils-and-3-are-cars-how-may-w
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# 51 people enter a raffle with 10 prizes; 7 are pencils and 3 are cars. How may ways are there to give out the prizes?
Assume that no one can win more than one prize.
If the prizes were all different, then we have the case that order matters and repeats are allowed, meaning there are $P(51, 10)$ ways of handing out the prizes.
But the prizes are not all different.
I know that I need to:
1. Define an equivalence relation. Should I define the relation to be two prizes are the same given they are both pencils or both cars, or should I define two prizes to be the same provided that they are given to the same person?
2. Count the equivalence classes. I will need to know the answer to #1 to do this.
EDIT: My attempt at the solution.
Define two prizes to be the same provided that they are both pencils or both cars. This is an equivalence relation on our $P(51, 10)$ ways to hand out the prizes. There are $7!$ ways to hand out the pencils, and $3!$ ways to hand out the cars, so there are $\frac{P(51, 10)}{7!3!}$ equivalence classes. Thus there are $\frac{P(51, 10)}{7!3!}$ ways to hand out the prizes.
Is this solution correct?
• The solution is correct. I would do it differently. Assume the cars are identical and the pencils are identical and that a pencil is different from a car. There are $\binom{51}{3}$ ways to decide who gets the cars, For each of these ways, there are $\dots$. – André Nicolas Mar 2 '16 at 1:46
Your answer is correct. Since each person gets at most one prize, we simply need to choose which people receive the cars and which of the remaining people receive the pencils. Three of the fifty-one people receive a car and seven of the remaining forty-eight people receive a pencil. Hence, the number of ways the prizes can be distributed is $$\binom{51}{3}\binom{48}{7}$$
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2019-10-14 13:07:41
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https://physics.stackexchange.com/questions/257259/question-on-doing-the-integral-for-fermi-golden-rule
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# Question on doing the integral for Fermi golden rule
Today in the lecture, my professor did something which confused me
As an example, we consider the photoelectric effect, in which an electron bound in a Coulomb potential is ionized after interacting with an external electromagnetic field. [...] The absorption rate is given by $$\Gamma_{i\rightarrow f}=\frac{4a_{0}^{3}e^{2}}{m^{2}\pi\hbar^{4}c^{2}}\frac{(\mathbf{A}_{0}\cdot\mathbf{p}_{f})^{2}}{(1+(p_{f}a_{0}/\hbar^{2})^{4}}\delta(p_{f}^{2}/2m-E_{i}-\hbar\omega)$$
This gives us the rate for a precise final momentum $p_{f}$ . Typically, what we want to know is the rate of electrons detected in a solid angle $\mathrm{d}\Omega$ $$\frac{\mathrm{d}\Gamma}{\mathrm{d}\Omega}=\int_{0}^{\infty}p_{f}^{2}\,\mathrm{d}p_{f}\,\Gamma_{i\rightarrow p_{f}}$$
Doing the $p_{f}$ integral, we have $$\frac{\mathrm{d}\Gamma}{\mathrm{d}\Omega}=\frac{4a_{0}^{3}e^{2}p_{f}}{m\pi\hbar^{4}c^{2}}\frac{(\mathbf{A}_{0}\cdot\mathbf{p}_{f})^{2}}{(1+(p_{f}a_{0}/\hbar^{2})^{4}}$$
where $p_{f}=\sqrt{2m(E_{i}+\hbar\omega)}$.
but I don't get how the integral just multiplies a term $m \, p_f$ to the first expression. I thought that the $\delta$ function replace $p_f$ with $\sqrt{2m(E_{i}+\hbar\omega)}$.
The delta function $\delta(x)$ has unit area, but the function $\delta(2x)$ is "half as wide" and thus has half as much area; thus you can pick up extra factors from 'how fast' you cross the peak of the delta function. The general identity is $$\delta(f(x)) = \sum \frac{\delta(x-x_i)}{\big| df/dx|_{x=x_i} \big|}$$ where the $x_i$ are the roots of $f$. In this case the factor you pick up is $$p_f^2 \left(\frac{d}{dp_f}(p_f^2/2m - E_i - \hbar \omega) \right)^{-1} = p_f^2 (m/p_f) = m p_f.$$
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2019-08-20 10:36:08
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http://sci-gems.math.bas.bg/jspui/handle/10525/2734
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Please use this identifier to cite or link to this item: http://hdl.handle.net/10525/2734
Title: Zolotarev's proof of Gauss reciprocity and Jacobi symbols Authors: Szyjewski, Marek Keywords: Jacobi SymbolGauss ReciprocityPermutations Issue Date: 2011 Publisher: Institute of Mathematics and Informatics Bulgarian Academy of Sciences Citation: Serdica Mathematical Journal, Vol. 37, No 3, (2011), 251p-260p Abstract: We extend to the Jacobi symbol Zolotarev's idea that the Legendre symbol is the sign of a permutation, which leads to simple, strightforward proofs of many results, the proof of the Gauss Reciprocity for Jacobi symbols including. Description: 2000 Mathematics Subject Classification: Primary 11A15. URI: http://hdl.handle.net/10525/2734 ISSN: 1310-6600 Appears in Collections: Volume 37, Number 3
Files in This Item:
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2022-10-06 10:08:33
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https://notenik.app/knowledge-base/EPUB/html/version-7.3.0.html
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Notenik Knowledge Base
Back to Notenik.app
### 16.51 Version 7.3.0
Date: 30 Sep 2021
Released on September 30, 2021
##### Improved Seq and Level Defaults for Drag and Drop
When pasting an item (such as a URL) into a List sorted by Seq, and when the drop point is between existing rows, Notenik will now do a better job of setting reasonable defaults for both Seq and Level for the new Note.
##### Improved Recognition of Parent Realm Folders
Notenik allows you to drag a folder to be opened onto its app icon in the dock. That folder can be either a Notenik Collection or a parent folder containing Notenik Collections. Before this change, if a folder contained a single text file named robots.txt, then that would be treated as a Note, and so the folder would be opened as a Collection. After this change, such a folder will be more productively treated as the object of an Open Parent Realm command.
##### Parent Realm Folders Now Appear on Open Recent Menu
After you execute the Open Parent Realm command (either explicitly via the File menu, or implicitly by dragging a folder onto the app icon), the Parent Realm folder will now be added to the the Open Recent menu, making it available to be easily reopened later.
##### Streamlined New Collection process
It seemed a bit confusing to have so many different options for creating a new Collection, so I’ve combined them. Now there is just one File menu option, that says New Collection…. This option walks you through several screens where you can pick a location, pick a name, and pick a Collection type, and then shows you the Collection Settings screen where you can make any final adjustments to the configuration of your New Collection.
##### Saving Security-Scoped Bookmarks
Notenik has been enhanced to try to extend the life of access permissions for Collections assigned Shortcuts, so as to reduce the number of times a user has to re-authorize access to a folder. See Tailor Collection Settings for info on assigning a Shortcut to a Collection.
##### Undo Provided for Note Deletions
If you delete a Note by mistake, then you can use the Undo function (beneath the Edit menu) to undo the deletion, with the only caveat being that any note attachments will not be restored.
Next: Version 7.2.0
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2023-02-01 05:39:13
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http://www.helpteaching.com/tests/1190710/arithmetic-sequences
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##### Print Instructions
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## Arithmetic Sequences
1.
Find the next three terms for the sequence. $14,34,54,74,94,...$
1. 114, 134, 154
2. 188, 208, 228
3. 104, 124, 144
4. 84, 104, 124
2.
In the following sequence, what is the common difference? 3, 10, 17, 23, ...
1. 3
2. 23
3. 7
4. None of the above
3.
Determine $d$ for the following sequence: $4,7,10,13,16....$
1. 3
2. 4
3. 16
4. 1
5. none of these are correct
4.
What is the common difference of the arithmetic sequence 9, -1, -11, -21,...?
1. -10
2. -9
3. 9
4. 10
5.
Using the explicit formula, find the 21st term. $a_n=12+(n-1)6$
1. 100
2. 132
3. 120
4. 192
6.
Find the 20th term of the sequence: 3, 8, 13, 18,...
1. 95
2. 96
3. 97
4. 98
7.
Find the 100th term in the sequence: -3, -5, -7, -9, ...
1. 195
2. -201
3. 201
4. -195
8.
The $n^(th)$ term of the arithmetic progression $-3, -8, -13, ...$ is
1. $2+5n$
2. $8+5n$
3. $2-5n$
4. $8-5n$
9.
In the explicit rule $f(n)=31+4(n-1)$, the common difference is 31.
1. True
2. False
10.
In the recursive rule, $f(1)=5, \ \ f(n)=f(n-1)-15 " for " n>=2$, the common difference is 15.
1. True
2. False
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2017-12-12 06:20:42
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https://www.maxwell.vrac.puc-rio.br/colecao.php?strSecao=resultado&nrSeq=1814@2
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INFORMAÇÕES SOBRE DIREITOS AUTORAIS
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A violação de direitos autorais é passível de sanções civis e penais.
Coleção Digital
Título: PROGRAMMING VIA INTERFACE
Instituição: PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO - PUC-RIO
Autor(es):
Número do Conteúdo: 1814
Catalogação: 10/08/2001 Idioma(s): PORTUGUESE - BRAZIL
Tipo: TEXT Subtipo: THESIS trabalho premiado
Natureza: SCHOLARLY PUBLICATION
In the past few years, we have witnessed an increase in software functionality as an attempt to meet most users needs. This approach brings about serious usability challenges, due to an increase in application complexity as well. In order to try and meet users needs, without overloading the application with functionality that is rarely used, there is a tendency to allow end users to configure or program applications, by means of mechanisms that support the so-called end user programming. However, many existing techniques fail to attain acceptable thresholds of usefulness and usability. This work addresses some of the challenges posed by extensible applications. We follow an approach that drops some walls between interface and extension. This approach brings some extension mechanisms to the interface, and readily accessible to end- users, namely extensions based on the semantic-pragmatic resources of metaphors and metonymies. These mechanisms were chosen due to the acknowledgment of the Cognitive Sciences of their critical role in our reasoning processes, especially when we try to describe or understand complex or abstract concepts (Lakoff e Johnson, 1980; Lakoff, 1987; Lakoff, 1993; Ortony, 1993). We describe an extensible application model that makes use of a knowledge base in which we represent the domain and application elements that may be extended, as well as the necessary classifications for calculating the possible extensions. Our model takes into account the communicative aspects of computer applications, and follows Semiotic Engineering (de Souza, 1993) principles to guarantee the consistency between the original application and the extended one. For that purpose, our model entails the representation of rules that constrain interface amendments, so that extended functionality is adequately reflected at the resulting interface.
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2020-10-27 21:23:16
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http://gmatclub.com/forum/if-2-98-256l-n-where-l-and-n-are-integers-and-132209.html
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# If 2^98=256L+N, where L and N are integers and
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If 2^98=256L+N, where L and N are integers and [#permalink]
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If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
[Reveal] Spoiler: OA
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Last edited by Bunuel on 08 May 2012, 00:02, edited 1 time in total.
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07 May 2012, 21:28
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Quote:
If 2^98+L, where L and N are integers and 0<=N<=4, what is the value of N?
The question has not been stated in the correct form. Looking into the tests, I see that the actual question is:
If 2^98= 256L + N and 0<=N<=4, what is the value of N?
To solve this, note that 2^8 = 256, so 2^98 = 2^[(8*12)+2]=4*[256*256*......12 times]
As this is a multiple of 256, N can only be 0.
Choice A
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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08 May 2012, 00:02
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monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
Given: $$2^{98}=2^8*L+N$$ --> divide both parts by $$2^8$$ --> $$2^{90}=L+\frac{N}{2^8}$$. Now, as both $$2^{90}$$ and L are an integers then $$\frac{N}{2^8}$$ must also be an integer, which is only possible for $$N=0$$ (since $$0\leq{N}\leq4$$).
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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08 May 2012, 01:30
Bunuel wrote:
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
Given: $$2^{98}=2^8*L+N$$ --> divide both parts by $$2^8$$ --> $$2^{90}=L+\frac{N}{2^8}$$. Now, as both $$2^{90}$$ and L are an integers then $$\frac{N}{2^8}$$ must also be an integer, which is only possible for $$N=0$$ (since $$0\leq{N}\leq4$$).
Dear Bunuel,
could you pls explain why N/2^8 = 0 ?
why it could not be another multiple of 2?
L is also there? why we are sure L+N/2^8 do not = 2^90?
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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08 May 2012, 01:33
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kashishh wrote:
Bunuel wrote:
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
Given: $$2^{98}=2^8*L+N$$ --> divide both parts by $$2^8$$ --> $$2^{90}=L+\frac{N}{2^8}$$. Now, as both $$2^{90}$$ and L are an integers then $$\frac{N}{2^8}$$ must also be an integer, which is only possible for $$N=0$$ (since $$0\leq{N}\leq4$$).
Dear Bunuel,
could you pls explain why N/2^8 = 0 ?
why it could not be another multiple of 2?
L is also there? why we are sure L+N/2^8 do not = 2^90?
Sure. Given that $$0\leq{N}\leq4$$, so N can only be 0, 1, 2, 3, or 4. So, N/2^8 is an integer only for N=0.
Hope it's clear.
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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08 May 2012, 01:44
@ Bunuel
yes, got it! thanx.
its integer - its value could only between >0 and <4!
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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09 May 2012, 13:39
1
KUDOS
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
Another way to solve this question:
Points to be remember:
1. L and N are integers
2. N could be any integer from 0 to 4.
Since 2^98 and 256L are even, N must be even. So N cannot be 1 and 3.
2^98 = 256L+N
2^98 = 2^8L+N
L = (2^98 - N)/2^8
L = 2^90 - N/2^8
If N = 0, L has integer value. Keep it.
If N = 2, L does not have integer value. Eliminate it.
If N = 4, L does not have integer value. Eliminate it.
Therefore, L has to be zero (A).
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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27 Nov 2012, 17:18
256= 2^8 and it is being multiplied by L. We don't really have to worry about L.
Just focus on 2^8 + N.
If N is 2, then 2(2^7 + 1) isn't going to result in a factor of 2, nor would N = 4 b/c 2^8+2^2 = 2^2(2^6+1). Same problem
Thus N has to be 0.
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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20 Dec 2012, 03:02
Another approach to tackle this problem:
The given relation is:
$$2^98=256L+N$$
This is actually written in "remainder format" i.e. X=Quotient*some integer + Remainder.
Here X=$$2^98$$, Quotient=256 and Remainder=0.
We just have to check whether $$256$$ OR $$2^8$$ divides $$2^ 98$$. If yes, then the value of N is straightaway 0. No need to check choices even.
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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27 May 2013, 16:02
Marcab wrote:
Another approach to tackle this problem:
The given relation is:
$$2^98=256L+N$$
This is actually written in "remainder format" i.e. X=Quotient*some integer + Remainder.
Here X=$$2^98$$, Quotient=256 and Remainder=0.
We just have to check whether $$256$$ OR $$2^8$$ divides $$2^ 98$$. If yes, then the value of N is straightaway 0. No need to check choices even.
Could you tell me if I'm understanding it correctly?
What if we had 12/5 = 2 remainder 2? Then in remainder format we would have 2 * 5 + 2 = 12.
So according to what you're saying, if we just have to check if 2 can divide 12? In this case it does, but the remainder is 2 not 0.
Please, help me in understanding where I'm going wrong.
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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28 May 2013, 01:36
youngkacha wrote:
Marcab wrote:
Another approach to tackle this problem:
The given relation is:
$$2^98=256L+N$$
This is actually written in "remainder format" i.e. X=Quotient*some integer + Remainder.
Here X=$$2^98$$, Quotient=256 and Remainder=0.
We just have to check whether $$256$$ OR $$2^8$$ divides $$2^ 98$$. If yes, then the value of N is straightaway 0. No need to check choices even.
Could you tell me if I'm understanding it correctly?
What if we had 12/5 = 2 remainder 2? Then in remainder format we would have 2 * 5 + 2 = 12.
So according to what you're saying, if we just have to check if 2 can divide 12? In this case it does, but the remainder is 2 not 0.
Please, help me in understanding where I'm going wrong.
Your reasoning unfortunately is incorrect since 5 is the divisor in question. The first 2 obtained is the quotient (which is the integer result obtained when dividing the numerator with the denominator) and cannot be used to question whether 2 divides 12 or not.
To further illustrate, take a look at the problem itself : $$2^98 = 256*L + N$$ which can be rephased as the following : does 256 divide $$2^98$$ ? (Since in this instance $$2^98$$ is the numerator, 256 is the denominator, L is the quotient and N is the remainder). To which the answer, obviously, is yes, since 256 can be written as a power of two, in this case 2^8.
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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28 May 2013, 02:17
1
KUDOS
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
256=2^8=> 2^98 can be written as 2^90*2^8 such that L can be treated as 2^90. hence N=0.
Ans A
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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28 May 2013, 16:44
Virgilius wrote:
youngkacha wrote:
Marcab wrote:
Another approach to tackle this problem:
The given relation is:
$$2^98=256L+N$$
This is actually written in "remainder format" i.e. X=Quotient*some integer + Remainder.
Here X=$$2^98$$, Quotient=256 and Remainder=0.
We just have to check whether $$256$$ OR $$2^8$$ divides $$2^ 98$$. If yes, then the value of N is straightaway 0. No need to check choices even.
Could you tell me if I'm understanding it correctly?
What if we had 12/5 = 2 remainder 2? Then in remainder format we would have 2 * 5 + 2 = 12.
So according to what you're saying, if we just have to check if 2 can divide 12? In this case it does, but the remainder is 2 not 0.
Please, help me in understanding where I'm going wrong.
Your reasoning unfortunately is incorrect since 5 is the divisor in question. The first 2 obtained is the quotient (which is the integer result obtained when dividing the numerator with the denominator) and cannot be used to question whether 2 divides 12 or not.
To further illustrate, take a look at the problem itself : $$2^98 = 256*L + N$$ which can be rephased as the following : does 256 divide $$2^98$$ ? (Since in this instance $$2^98$$ is the numerator, 256 is the denominator, L is the quotient and N is the remainder). To which the answer, obviously, is yes, since 256 can be written as a power of two, in this case 2^8.
Sorry, but I'm still lost. Marcab has the quotient as 256, but you're saying 256 is the divisor and L is the quotient?
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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26 Nov 2015, 06:57
Bunuel wrote:
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
Given: $$2^{98}=2^8*L+N$$ --> divide both parts by $$2^8$$ --> $$2^{90}=L+\frac{N}{2^8}$$. Now, as both $$2^{90}$$ and L are an integers then $$\frac{N}{2^8}$$ must also be an integer, which is only possible for $$N=0$$ (since $$0\leq{N}\leq4$$).
I'm sorry but if you're dividing both sides of the equation by $$2^8$$ won't it cancel on the right side of the equation? So how do we come to $$\frac{N}{2^8}$$ ?
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Re: If 2^98=256L+N, where L and N are integers and [#permalink]
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26 Nov 2015, 07:10
1
KUDOS
Expert's post
redfield wrote:
Bunuel wrote:
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
Given: $$2^{98}=2^8*L+N$$ --> divide both parts by $$2^8$$ --> $$2^{90}=L+\frac{N}{2^8}$$. Now, as both $$2^{90}$$ and L are an integers then $$\frac{N}{2^8}$$ must also be an integer, which is only possible for $$N=0$$ (since $$0\leq{N}\leq4$$).
I'm sorry but if you're dividing both sides of the equation by $$2^8$$ won't it cancel on the right side of the equation? So how do we come to $$\frac{N}{2^8}$$ ?
$$2^{98}=2^8*L+N$$
Dividing both parts by $$2^8$$:
$$\frac{2^{98}}{2^8}=\frac{2^8*L+N}{2^8}$$;
$$2^{98-8}=\frac{2^8*L}{2^8}+\frac{N}{2^8}$$
$$2^{90}=L+\frac{N}{2^8}$$.
Hope it's clear.
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If 2^98=256L+N, where L and N are integers and [#permalink]
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26 Nov 2015, 09:13
monir6000 wrote:
If $$2^{98} = 256L + N$$, where $$L$$ and $$N$$ are integers and $$0 \le N \le 4$$ , what is the value of $$N$$ ?
A. 0
B. 1
C. 2
D. 3
E. 4
The first thing to note here is that LHS is an even number, hence RHS should also be even.
This elements N = 1,3
Now,
$$2^{98} = 2^8L + N$$, Diving both the sides by $$2^8$$
$$2^{90} = L + N/2^8$$,
Out of 0, 2 and 4, N can only be 0 for RHS to be an even number.
Option A
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If 2^98=256L+N, where L and N are integers and [#permalink] 26 Nov 2015, 09:13
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# If 2^98=256L+N, where L and N are integers and
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https://learn.careers360.com/engineering/question-a-block-of-mass-is-at-rest-at-the-edge-of-a-table-of-height-a-bullet-of-mass-collides-with-the-block-and-sticks-to-it-if-the-velocity-of-the-bullet-is-in-the-horizontal-direction-just-before-the-collision-then-the-kinetic-energy-just-before-the-combined-system-strikes-the-floor-is-take-assume-there-is-no-rotational-motion-and-loss-of-energy-after-the-co/
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# A block of mass $\inline 1.9\; kg$ is at rest at the edge of a table, of height $\inline 1\; m$. A bullet of mass $\inline 0.1\; kg$ collides with the block and sticks to it. If the velocity of the bullet is $\inline 20\; m/s$ in the horizontal direction just before the collision then the kinetic energy just before the combined system strikes the floor, is [ Take $\inline g=10\; m/s^{2}.$ Assume there is no rotational motion and loss of energy after the collision is negligable.] Option: 1 Option: 2 Option: 3 Option: 4
Let the velocity of the combined system after a collision at A is V
\begin{aligned} &\text { Applying law of conservation of linear momentum }\\ &\Rightarrow 0.1 \times 20=(1.9+0.1) \mathrm{V}\\ &\Rightarrow 2=2 \mathrm{~V}\\ &\Rightarrow V=1 \mathrm{~m} / \mathrm{sec} \end{aligned}
So
At A
$\begin{array}{l} \mathrm{KE}=( \frac{1}{2})* \mathrm{mv}^{2}=( \frac{1}{2})* 2*(1)^{2}=1 \mathrm{~J} \\ PE=mgh=2 \times 10 \times 1=20 \ J\\ \mathrm{TE}=\mathrm{KE}+\mathrm{mgh}=1+20=21 \mathrm{~J} \end{array}$
As Total energy is conserved
So
$\\(\mathrm{TE})_A=(\mathrm{TE})_B\\ (\mathrm{TE})_B=21 \ J$
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https://proofwiki.org/wiki/Category:Inverse_Hyperbolic_Tangent
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Category:Inverse Hyperbolic Tangent
This category contains results about Inverse Hyperbolic Tangent.
Definitions specific to this category can be found in Definitions/Inverse Hyperbolic Tangent.
The inverse hyperbolic tangent is a multifunction defined on $S$ as:
$\forall z \in S: \tanh^{-1} \paren z := \set {w \in \C: z = \tanh \paren w}$
where $\tanh \paren w$ is the hyperbolic tangent function.
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https://web2.0calc.com/questions/a-stone-is-thrown-straight-down-from-the-edge-of-a-roof-725-feet-above-the-ground-at-a-speed-of-7-feet-per-second-remembering-that-the-ac
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+0
# A stone is thrown straight down from the edge of a roof, 725 feet above the ground, at a speed of 7 feet per second. Remembering that the ac
0
2033
3
A stone is thrown straight down from the edge of a roof, 725 feet above the ground, at a speed of 7 feet per second. Remembering that the acceleration due to gravity is -32 feet per second squared, how high is the stone 3 seconds later? At what time does the stone hit the ground? What is the velocity of the stone when it hits the ground?
physics
Guest Jan 29, 2015
#1
+26750
+8
1. Use s = ut + (1/2)at2, where s = distance travelled, u = initial velocity, a = acceleration, t = time.
s = 7*3 +(1/2)*32*9 = 165 ft., so the stone is 725 - 165 = 560 ft off the ground.
2. The stone hits the ground when s = 725, so: 725 = 7*t +(1/2)*32*t2
$${\mathtt{16}}{\mathtt{\,\times\,}}{{\mathtt{t}}}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{t}}{\mathtt{\,-\,}}{\mathtt{725}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{t}} = {\mathtt{\,-\,}}{\frac{\left({\mathtt{3}}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{5\,161}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}\right)}{{\mathtt{32}}}}\\ {\mathtt{t}} = {\frac{\left({\mathtt{3}}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{5\,161}}}}{\mathtt{\,-\,}}{\mathtt{7}}\right)}{{\mathtt{32}}}}\\ \end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{t}} = -{\mathtt{6.953\: \!759\: \!395\: \!873\: \!178\: \!7}}\\ {\mathtt{t}} = {\mathtt{6.516\: \!259\: \!395\: \!873\: \!178\: \!7}}\\ \end{array} \right\}$$
The only positive solution is t = 6.516 seconds
3. Use v2 = u2 + 2as where v is final velocity.
v2 = 49 + 2*32*725
$${\mathtt{v}} = {\sqrt{{\mathtt{49}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{32}}{\mathtt{\,\times\,}}{\mathtt{725}}}} \Rightarrow {\mathtt{v}} = {\mathtt{215.520\: \!300\: \!667\: \!941\: \!719\: \!5}}$$
v = 215.52 ft/sec
.
Alan Jan 29, 2015
#1
+26750
+8
1. Use s = ut + (1/2)at2, where s = distance travelled, u = initial velocity, a = acceleration, t = time.
s = 7*3 +(1/2)*32*9 = 165 ft., so the stone is 725 - 165 = 560 ft off the ground.
2. The stone hits the ground when s = 725, so: 725 = 7*t +(1/2)*32*t2
$${\mathtt{16}}{\mathtt{\,\times\,}}{{\mathtt{t}}}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{t}}{\mathtt{\,-\,}}{\mathtt{725}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{t}} = {\mathtt{\,-\,}}{\frac{\left({\mathtt{3}}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{5\,161}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}\right)}{{\mathtt{32}}}}\\ {\mathtt{t}} = {\frac{\left({\mathtt{3}}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{5\,161}}}}{\mathtt{\,-\,}}{\mathtt{7}}\right)}{{\mathtt{32}}}}\\ \end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{t}} = -{\mathtt{6.953\: \!759\: \!395\: \!873\: \!178\: \!7}}\\ {\mathtt{t}} = {\mathtt{6.516\: \!259\: \!395\: \!873\: \!178\: \!7}}\\ \end{array} \right\}$$
The only positive solution is t = 6.516 seconds
3. Use v2 = u2 + 2as where v is final velocity.
v2 = 49 + 2*32*725
$${\mathtt{v}} = {\sqrt{{\mathtt{49}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{32}}{\mathtt{\,\times\,}}{\mathtt{725}}}} \Rightarrow {\mathtt{v}} = {\mathtt{215.520\: \!300\: \!667\: \!941\: \!719\: \!5}}$$
v = 215.52 ft/sec
.
Alan Jan 29, 2015
#2
+19620
+5
3. also final velocity v:
$$v=v_0+at_{\small{\text{stone hits the ground}}} \quad v_0 = 7\quad t = 6.51625939587s \\ v = 7 + 32 * 6.51625939587 = 215.5203 \ \frac{ft}{s}\\$$
heureka Jan 29, 2015
#3
+87294
+5
Here's a graph of the position function and the velocity fuction that demonstrates Alan's and Heureka's answers....
GRAPH
CPhill Jan 29, 2015
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2018-07-17 21:25:11
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https://yihui.name/cn/2007/06/boosting-good-good-study-day-day-up/
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# Boosting: Good Good Study, Day Day Up!
### 谢益辉 / 2007-06-04
After writing down the title, I seemed to have forgotten what I wanted to say *____*!!!
OK, the idea came back to my mind again.
When Dr. CHEN was making a presentation on Leo Breiman’s paper “SOME INFINITY THEORY FOR PREDICTOR ENSEMBLES”, I suddenly got a further understanding on boosting and bagging (though I still don’t understand some details). I believe there are some very very important issues about the philosophy of machine learning, which are actually hardly emphasized (or even mentioned) in Chinese books or papers I ever read.
Take boosting for example: I just describe this algorithm as “Good Good Study, Day Day Up” because it really “studies” from the past results to improve future classifiers.
That’s where the machine is “learning”, I think.
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2017-09-25 02:25:58
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https://stats.stackexchange.com/questions/74877/how-to-analyze-intra-rater-reliability-with-31-raters-who-all-rated-4-subjects-t
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# How to analyze intra-rater reliability with 31 raters who all rated 4 subjects twice
I'm trying to analyze the intra-rater reliability of an occupational therapy assessment.
The assessment consists of 57 items, where some items are ratio data and some items are ordinal data. In my study 31 raters rated 4 subjects (on video) twice (time 1 and time 2) with a six week interval. So I have scores on each of the 57 items, for each subject, for each time and each rater.
Rater1Item 1, Rater1Item2 .... Rater1Item 57.... Rater31Item1....Rater31Item57
Subject1 Time1
Subject2 Time1
....
Subject3 Time2
Subject4 Time2
My first question is about the set-up of the database, I'm using SPSS. As showed above, is this the right set-up or do I need to change the set up and put the raters in the rows and the subjects in the colomns?
My second question, I found out I can use ICC and Bland & Altman to analyse the intra-rater reliability. Are these two suitable or are there other statistical methods? The kappa statistic seems not very suitable since I have 31 raters, each rating 4 subjects. Or is there a way to deal with the kappa statistic and such a big database?
My third question is, which ICC can I use for the ratio data to calculate the intra-rater reliabiliy? I read different suggestions in the literature (ICC 1.1 or ICC 3.1)
My fourth question is, if I use Bland & Altman the first thing I need to do is calculating the mean of time 1 and time 2. Do I need to do this for each item, each subject and each rater independently or can I calculate the mean for each item on each subject for all raters together? Or wouldn't it make sense to calculate this for the raters together, because the mean on both times can be the same, without have agreement (for example rater 1 scores less on time 2 and rater 2 scores higher on time 2, keeping the mean the same on both time 1 and time 2)
My last question, when I draw the Bland & Altman plot can I do this for each item with all 4 subjects and all 31 raters, having 124 dots in my plot?
• Welcome to Cross Validated Stack Exchange (CV SE). Usually, it helps if you ask one question at a time. Narrowing down your doubts increases your chances to get a good answer. For more information about CV SE see the help center page. Tks. – Andre Silva Nov 7 '13 at 15:25
• This question is quite tricky, so I start with just a tiny comment: Bland-Altman-plots are designed to study the agreement between two different methods, not different raters. In daily work this is essential because the raters will change. (Or put differently, the raters you are using can be considered as a random draw of all possible raters whereas in Bland-Altman settings, the methods are fixed). – Michael M Nov 7 '13 at 15:27
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2019-07-19 20:58:28
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https://homework.cpm.org/category/CCI_CT/textbook/pc/chapter/11/lesson/11.1.4/problem/11-59
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### Home > PC > Chapter 11 > Lesson 11.1.4 > Problem11-59
11-59.
Show that 4 cos (x + ) = 2 cos x − 2 sin x. Homework Help ✎
Use the Angle Sum Identity.
$4\left( \cos(\textit{x})\cos\left( \frac{\pi}{3} \right) - \sin(\textit{x})\sin\left( \frac{\pi}{3} \right)\right) =$
Substitute the exact values for sine and cosine of π/3. Then simplify.
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2019-10-23 15:55:33
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http://openstudy.com/updates/5615927be4b02b3e025f107f
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## Compassionate one year ago A ball is shot from a cannon into the air with an upward velocity of 40 ft/sec. The equation that gives the height (h) of the ball at any time (t) is: h(t)= -16t2 + 40ft + 1.5. Find the maximum height attained by the ball.
1. Mehek14
$$\tt{x=\dfrac{-b}{2a}}$$
2. Compassionate
$\frac{ -b }{ 2a}$ $\frac{ -40 }{ -32 }$ Time = 8
3. SolomonZelman
4. SolomonZelman
$$h(t)= -16t^2 + 40t + 1.5$$ ?
5. SolomonZelman
the max height will be the vertex (because the parabola opens down, and that is because the leading coefficient is negative)
6. Compassionate
I need to find the maximum height. Yes, that's the equation. So my time is 8, right? To find my height, plug 8 in.
7. SolomonZelman
You don't need the height, if you are given that function you can find the vertex and that will be your maximum height.
8. Compassionate
To find max height, I need to first obtain the time it takes the ball to reach it, then plug in t.
9. Mehek14
how did you get time = 8? $$\tt{\dfrac{-40}{-32}=1.25}$$ not 8
10. Compassionate
I got 8 because my calculator is autistic and I am jut realizing this. -16(1.25)^2 + 40(1.25) + 1.5 -25 + 50 + 1.5 25 + 1.5 Height = 26.5
11. Mehek14
maximum height is 26.5 you get the time 1.25 and plug it in for t
12. Compassionate
Thanks! I got it :) `
13. Mehek14
when you use $$\tt{x=\dfrac{-b}{2a}}$$, you find the time then you plug the time in for the variable and yw :]
14. SolomonZelman
$$\large\color{black}{ \displaystyle h(t)=-16t^2-40t+1.5 }$$ $$\large\color{black}{ \displaystyle h(t)=-16(t^2+2.5t)+1.5 }$$ side caclulation: $$\large\color{black}{ \displaystyle 2.5\div2=1.25 }$$ $$\large\color{black}{ \displaystyle 1.25^2=1.5625 }$$ $$\large\color{black}{ \displaystyle h(t)=-16(t^2+2.5t+1.5625-1.5625)+1.5 }$$ $$\large\color{black}{ \displaystyle h(t)=-16(t^2+2.5t+1.5625)+(-16)(-1.5625)+1.5 }$$ $$\large\color{black}{ \displaystyle h(t)=-16(t+1.25)^2+25+1.5 }$$ $$\large\color{black}{ \displaystyle h(t)=-16(t+1.25)^2+26.5 }$$ So the height is 26.5 and it occurs at t=1.25.
15. SolomonZelman
(via completing the square)
16. Compassionate
I never learned how to complete squares :(
17. Compassionate
Okay, so can I shoot one more at you guys?
18. Mehek14
don't you learn completing the square in Alg 1?
19. SolomonZelman
I don't think there is a single particular order for learning different concepts in math.... I have seen people who asked how to find a slope in DE section.
20. SolomonZelman
Well, completing the square is something that you can probably browse and find a good resource quite fast:)
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2016-10-24 20:16:00
|
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https://esp.mit.edu/teach/teachers/jkoppel/bio.html
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# ESP Biography
## JAMES KOPPEL, CS grad student at MIT
Major: Computer Science
College/Employer: MIT
Not Available.
## Past Classes
(Clicking a class title will bring you to the course's section of the corresponding course catalog)
W15030: Codenames in Spark 2022 (Mar. 12 - 13, 2022)
Play a board game of guesswork and word association with us! Codenames has two teams compete to guess the other team's secret words based on one word clues. $$\textbf{This is a walk-in activity; you can drop in and out of this class at will.}$$
W15031: GeoGuessr in Spark 2022 (Mar. 12 - 13, 2022)
Come help guess where we are in the world based on one picture! $$\textbf{This is a walk-in activity; you can drop in and out of this class at will.}$$
W15032: Wordle (and clones) in Spark 2022 (Mar. 12 - 13, 2022)
Come play Wordle and similar games and get really good at guessing esoteric words. $$\textbf{This is a walk-in activity; you can drop in and out of this class at will.}$$
Z14694: Supercharging Your Learning in Splash 2021 (Nov. 20 - 21, 2021)
Want to spend less time studying while remembering more? In this class, we’ll learn about the science of learning and memory, and share some concrete things you can do to remember things you learn forever, get facts popping into your mind the moment you need them most, and make yourself understand something better than your teacher. We’ll also introduce you to real websites and apps you can use to put all this into practice as soon as class is over. Soon you’ll be able to ace classes just using the time you already spend walking or on the toilet.
H14169: Making deep friendships - Circling in Splash 2020 (Nov. 14 - 15, 2020)
Most of your Splash classes will be about objects and things. Some of your conversations will involve personal history, where you grew up, what you like and dislike. This class will be a third kind of conversation, about what our present experience is, as we're having it. Access to this level of conversation has a way of facilitating deep connections where you can feel deeply seen and welcomed. Circling is a practice about getting others' worlds, sharing what it's really like to be you, and having that be seen and reflected. Come experience the magic.
A13798: Make and Play a Didgeridoo in Spark 2020 (Mar. 14 - 15, 2020)
awuwuwuwuuuuweeorweeorwadelewadelewu! The didgeridoo is an Australian instrument that adds a tribal flair to any situation. In this class, we'll build our own didgeridoos out of PVC pipe, and then learn to play them. With the didgeridoo, you can create a variety of rhythms, produce animal noises, and make yourself sound like there's two people playing! For people with little to no experience.
M13920: Finite Automata in Spark 2020 (Mar. 14 - 15, 2020)
Would you like to find patterns in text? Prove your program doesn't have an infinite loop? Monitor a nuclear reactor? Find structure in DNA? In this class, you'll learn about finite automata. Finite automata, or "state machines" can be thought of as just moving a marker between some states according to some simple rules, but their simplicity hides deep mathematics and allows you to manipulate them in interesting ways. We'll start with the basic definition and take you through the math and into some powerful applications.
X13195: Being an Immovable Object in Splash 2019 (Nov. 23 - 24, 2019)
If you twist your shoulder in the right way, you can lift twice as much. Tense your abs in the right way, and you can punch three times as hard. Whether you like martial arts or yoga, dancing or football, or even if you just want to seem more confident when presenting, you can do more with less effort when you put your body in a position of stability. So come to this class and get better at everything!
X13196: Being a Proud Tribesman in Splash 2019 (Nov. 23 - 24, 2019)
Give an American soldier a heavy pack, and moving becomes harder. Give it to an African villager, and moving becomes easier. Turns out they're just better at walking than us. And standing and sitting. Come learn why everything you know about posture is wrong. Superpowers to be had from this class include the ability to see things directly behind you and being able to sleep on a wooden log. Some increase in height may be expected. Warning: Upon completion of this class, your life may feel like an endless massage. You may also experience a sudden urge to replace all your furniture.
M13360: Term Rewriting and Gröbner Bases in Splash 2019 (Nov. 23 - 24, 2019)
Solving systems of linear equations is easy. How about systems of polynomial equations? We're not really going to teach you that. Instead, we're going to teach you about Gröbner bases, a crazy way of representing spaces of polynomials, which also gives the ability to solve polynomial equations. Actually, we're not going to really teach you that either. Instead, we're going to go into a separate branch of mathematics called Term Rewriting and teach you about Knuth-Bendix Completion, a "meta-algorithm" which can take definitions of equality and give you an algorithm for telling whether two things are equal. We'll present Gröbner Bases as a special case of Knuth-Bendix Completion. We might even have time to solve a polynomial equation or two!
M12892: Finite Automata in Spark 2019 (Mar. 16 - 17, 2019)
Would you like to find patterns in text? Prove your program doesn't have an infinite loop? Monitor a nuclear reactor? Find structure in DNA? In this class, you'll learn about finite automata. Finite automata, or "state machines" can be thought of as just moving a marker between some states according to some simple rules, but their simplicity hides deep mathematics and allows you to manipulate them in interesting ways. We'll start with the basic definition and take you through the math and into some powerful applications.
A12893: Make and Play a Didgeridoo in Spark 2019 (Mar. 16 - 17, 2019)
awuwuwuwuuuuweeorweeorwadelewadelewu! The didgeridoo is an Australian instrument that adds a tribal flair to any situation. In this class, we'll build our own didgeridoos out of PVC pipe, and then learn to play them. With the didgeridoo, you can create a variety of rhythms, produce animal noises, and make yourself sound like there's two people playing! For people with little to no experience.
H12685: Neurodivergence in Splash 2018 (Nov. 17 - 18, 2018)
Neurological spectrum conditions, such as autism, Aspergers, etc. are growing more prevalent and well-represented in our society today. Come learn what these conditions are and what it is like to live with them, strengths and challenges facing the community, and how people on and off the spectrum can contribute to a neurodiverse world.
X12686: Being a Proud Tribesman in Splash 2018 (Nov. 17 - 18, 2018)
Give an American soldier a heavy pack, and moving becomes harder. Give it to an African villager, and moving becomes easier. Turns out they're just better at walking than us. And standing and sitting. Come learn why everything you know about posture is wrong. Superpowers to be had from this class include the ability to see things directly behind you and being able to sleep on a wooden log. Some increase in height may be expected. Warning: Upon completion of this class, your life may feel like an endless massage. You may also experience a sudden urge to replace all your furniture.
X12687: Being an Immovable Object in Splash 2018 (Nov. 17 - 18, 2018)
If you twist your shoulder in the right way, you can lift twice as much. Tense your abs in the right way, and you can punch three times as hard. Whether you like martial arts or yoga, dancing or football, or even if you just want to seem more confident when presenting, you can do more with less effort when you put your body in a position of stability. So come to this class and get better at everything!
M12145: Finite Automata in Spark 2018 (Mar. 17 - 18, 2018)
Would you like to find patterns in text? Prove your program doesn't have an infinite loop? Monitor a nuclear reactor? Find structure in DNA? In this class, you'll learn about finite automata. Finite automata, or "state machines" can be thought of as just moving a marker between some states according to some simple rules, but their simplicity hides deep mathematics and allows you to manipulate them in interesting ways. We'll start with the basic definition and take you through the math and into some powerful applications.
A12146: Make and Play a Didgeridoo in Spark 2018 (Mar. 17 - 18, 2018)
awuwuwuwuuuuweeorweeorwadelewadelewu! The didgeridoo is an Australian instrument that adds a tribal flair to any situation. In this class, we'll build our own didgeridoos out of PVC pipe, and then learn to play them. With the didgeridoo, you can create a variety of rhythms, produce animal noises, and make yourself sound like there's two people playing! For people with little to no experience.
X11803: Being an Immovable Object in Splash 2017 (Nov. 18 - 19, 2017)
If you twist your shoulder in the right way, you can lift twice as much. Tense your abs in the right way, and you can punch three times as hard. Whether you like martial arts or yoga, dancing or football, or even if you just want to seem more confident when presenting, you can do more with less effort when you put your body in a position of stability. So come to this class and get better at everything!
X11804: Being a Proud Tribesman in Splash 2017 (Nov. 18 - 19, 2017)
Give an American soldier a heavy pack, and moving becomes harder. Give it to an African villager, and moving becomes easier. Turns out they're just better at walking than us. And standing and sitting. Come learn why everything you know about posture is wrong. Superpowers to be had from this class include the ability to see things directly behind you and being able to sleep on a wooden log. Some increase in height may be expected. Warning: Upon completion of this class, your life may feel like an endless massage. You may also experience a sudden urge to replace all your furniture.
M11805: Gröbner Bases and Term Rewriting in Splash 2017 (Nov. 18 - 19, 2017)
Solving systems of linear equations is easy. How about systems of polynomial equations? We're not really going to teach you that. Instead, we're going to teach you about Gröbner bases, a crazy way of representing spaces of polynomials, which also gives the ability to solve polynomial equations. Actually, we're not going to really teach you that either. Instead, we're going to go into a separate branch of mathematics called Term Rewriting and teach you about Knuth-Bendix Completion, a "meta-algorithm" which can take definitions of equality and give you an algorithm for telling whether two things are equal. We'll present Gröbner Bases as a special case of Knuth-Bendix Completion. We might even have time to solve a polynomial equation or two!
M11292: Finite Automata in Spark 2017 (Mar. 11 - 12, 2017)
Would you like to find patterns in text? Prove your program doesn't have an infinite loop? Monitor a nuclear reactor? Find structure in DNA? In this class, you'll learn about finite automata. Finite automata, or "state machines" can be thought of as just moving a marker between some states according to some simple rules, but their simplicity hides deep mathematics and allows you to manipulate them in interesting ways. We'll start with the basic definition and take you through the math and into some powerful applications.
M11293: Chaotic Reduction: Play the Math in Spark 2017 (Mar. 11 - 12, 2017)
Chaotic Reduction is a computer game that turns mathematical problems into puzzles. We will study famous problems such as the Post Correspondence Problem and Conway's Soldiers in computer game form, and then make our own levels!
A11294: Make and Play a Didgeridoo in Spark 2017 (Mar. 11 - 12, 2017)
awuwuwuwuuuuweeorweeor<roaaaar>wadelewadelewu! The didgeridoo is an Australian instrument that adds a tribal flair to any situation. In this class, we'll build our own didgeridoos out of PVC pipe, and then learn to play them. With the didgeridoo, you can create a variety of rhythms, produce animal noises, and make yourself sound like there's two people playing! For people with little to no experience.
H11349: Circling - Intersubjective Meditation in Spark 2017 (Mar. 11 - 12, 2017)
Most of your Spark classes will be about objects and things. Some of your conversations will involve personal history, where you grew up, what you like and dislike. This class will be a third kind of conversation, about what our present experience is, as we're having it. There's a kind of magic to being deeply seen, and to being welcomed as you are. Circling is a practice about getting others' worlds, and sharing what it's really like to be you, and having that be seen and reflected. Come experience the magic
X10729: Being an Immovable Object in Splash 2016 (Nov. 19 - 20, 2016)
If you twist your shoulder in the right way, you can lift twice as much. Tense your abs in the right way, and you can punch three times as hard. Whether you like martial arts or yoga, dancing or football, or even if you just want to seem more confident when presenting, you can do more with less effort when you put your body in a position of stability. So come to this class and get better at everything!
X10730: Being a Proud Tribesman in Splash 2016 (Nov. 19 - 20, 2016)
Give an American soldier a heavy pack, and moving becomes harder. Give it to an African villager, and moving becomes easier. Turns out they're just better at walking than us. And standing and sitting. Come learn why everything you know about posture is wrong. Superpowers to be had from this class include the ability to see things directly behind you and being able to sleep on a wooden log. Some increase in height may be expected. Warning: Upon completion of this class, your life may feel like an endless massage. You may also experience a sudden urge to replace all your furniture.
M10731: Gröbner Bases and Term Rewriting in Splash 2016 (Nov. 19 - 20, 2016)
Solving systems of linear equations is easy. How about systems of polynomial equations? We're not really going to teach you that. Instead, we're going to teach you about Gröbner bases, a crazy way of representing spaces of polynomials, which also gives the ability to solve polynomial equations. Actually, we're not going to really teach you that either. Instead, we're going to go into a separate branch of mathematics called Term Rewriting and teach you about Knuth-Bendix Completion, a "meta-algorithm" which can take definitions of equality and give you an algorithm for telling whether two things are equal. We'll present Gröbner Bases as a special case of Knuth-Bendix Completion. We might even have time to solve a polynomial equation or two! Bring your generalization goggles, 'cause things are about to get abstract.
M10332: Chaotic Reduction: Play the Math in Spark 2016 (Mar. 12 - 13, 2016)
Chaotic Reduction is a computer game that turns mathematical problems into puzzles. We will study famous problems such as the Post Correspondence Problem and Conway's Soldiers in computer game form, and then make our own levels!
M10333: Finite Automata in Spark 2016 (Mar. 12 - 13, 2016)
Would you like to find patterns in text? Prove your program doesn't have an infinite loop? Monitor a nuclear reactor? Find structure in DNA? In this class, you'll learn about finite automata. Finite automata, or "state machines" can be though of as just moving a marker between some states according to some simple rules, but their simplicity hides deep mathematics and allows you to manipulate them in interesting ways. We'll start with the basic definition and take you through the math and into some powerful applications.
X9745: Being an Immovable Object in Splash 2015 (Nov. 21 - 22, 2015)
If you twist your shoulder in the right way, you can lift twice as much. Tense your abs in the right way, and you can punch three times as hard. Whether you like martial arts or yoga, dancing or football, or even if you just want to seem more confident when presenting, you can do more with less effort when you put your body in a position of stability. So come to this class and get better at everything!
X9747: Being a Proud Tribesman in Splash 2015 (Nov. 21 - 22, 2015)
Give an American soldier a heavy pack, and moving becomes harder. Give it to an African villager, and moving becomes easier. Turns out they're just better at walking than us. And standing and sitting. Come learn why everything you know about posture is wrong. Superpowers to be had from this class include the ability to see things directly behind you and being able to sleep on a wooden log. Some increase in height may be expected. Warning: Upon completion of this class, your life may feel like an endless massage. You may also experience a sudden urge to replace all your furniture.
M9748: Causal Inference in Splash 2015 (Nov. 21 - 22, 2015)
Big data is all the rage these days. Let's talk about some things that even infinite data can't do. First we'll use statistics to prove why you should never go to the doctor. Then we'll show that smoking prevents cancer. Once we've finally kicked the statisticians out of the room, you'll learn the right way to reason about causality. We'll resolve the age-old question of whether war causes poverty or poverty causes war, and show how to predict the results of a randomized controlled experiment without actually doing one.
C9958: Advanced Functional Programming in Splash 2015 (Nov. 21 - 22, 2015)
Oh sure, you could write a program that runs over all the elements of a list and does something, but that's not interesting. How about something that iterates over any data structure? Or a function that runs backwards? Maybe we'll even make the "printf" function type-safe. Monads and typeclasses will be among the easier things we cover in this class. This class will be taught in Haskell, but the concepts covered are more general.
S9543: Lecture Series - Research in HSSP Summer 2015 (Jul. 12, 2015)
Learn about current developments across math, science, and computing! Every week, a different guest speaker will talk about their current research. Find out some of the cool things that MIT students spend their time working on. Schedule: 7/12: "Civil Structures," Yasamin Tari 7/19: "Synchronization Inspired by Fireflies", Iva Bojic 7/26: "Skeletal Biology," Sara Elaine Strecker 8/2: "Chemistry," Sneha Shastry and Tej Shastry 8/9: "Solar Energy Conversion," Bikram Bhatia 8/16: "DNA Organization in the Nucleus," Wouter Meuleman
M9544: Lecture Series - Math in HSSP Summer 2015 (Jul. 12, 2015)
Want to learn how to keep secrets from your little sister or a well-funded intelligence agency? Why 19 is a happy number, but 20 isn't? How to count to infinity, and then some? Then sign up for this whirlwind tour of math! You'll learn about something completely different each week from a series of 6 speakers. Schedule: 7/12: "Prisoner's Dilemma," Elizabeth Proctor 7/19: "Intro to Group Theory", Andreea Bobu and Lara Booth 7/26: "Intro to Number Theory," Sam Bauman 8/2: "Infinities and Infinite-Dimensional Spaces," Yash Kothari 8/9: "Finding patterns in everyday life," Nisha Rajagopal 8/16: "Non-cooperative Games," Stirling Newberry
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2022-05-16 20:12:22
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http://lebenplusplus.de/2017/11/27/error-log-analysis-with-jq/
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# Error log analysis with jq
This is a step-by-step introduction into aggregating and analyzing errors from a JSON error log (where each error is a JSON object on a single line) with the tool jq. While most tutorials and documentation of jq focus on how to transform JSON objects to other JSON objects on a 1:1 basis, this tutorial is more about building aggregates, using an approach that takes a page out of functional programming.
The example error log looks like this:
{"ts":"2017-11-30 06:45:02","severity":"I","error":{"msg":"Reticulating splines","splines":1}}
{"ts":"2017-11-30 06:45:12","severity":"I","error":{"msg":"Probing froobles","names":["frb23","frb42"]}}
{"ts":"2017-11-30 06:45:57","severity":"E","error":{"msg":"Widget exploded"}}
## Pretty-printing
The single-line format of the JSON log file is not very readable and will probably exceed you terminal width. You can pretty-print it with
jq . error.log
The jq command always needs the filter parameter, in the example above that’s the . (the dot). It also needs some JSON input, in the example the file name error.log. jq will read each line of the input, apply the filter to it and print the output of the filter.
The . (the dot) is the simplest filter you can apply, it means “return current input item”.
By default, jq shows the indented object hierarchy and colorizes it. If you want to read the output in a pager program like less, you need to explicitly enable colorizing in jq and interpretation of the color codes in less like this:
jq --color-output . error.log | less -R
## Counting lines, the functional programming way
If you really want to only count lines, you should use a command like wc -l, but it can also be done with jq:
jq -s length error.log
The -s parameter instructs jq to “slurp” the whole file into an array before processing (compare the output when using the . filter with and without the -s option). length is a function that returns the length of an array and is applied to the whole data structure.
Reading the whole file into memory will fail for big files and in future steps we’ll count only specific lines. So we’ll develop a different method for counting, based on the builtin functions reduce and inputs.
The following commands produce the same output:
jq -s . error.log
jq -n 'reduce inputs as $obj ([]; . + [$obj])' error.log
Note the single quotes around the filter in the second command, they prevent the dollar sign to be interpreted as shell variables. The -n parameter prevents jq from reading the input file error.log immediately. Instead, the filter gets null as input. The null is ignored and instead we use the reduce filter to iterate over inputs. inputs is a “filter” that returns the objects from the specified input files, one by one.
The reduce function is a concept from functional programming. It takes three parameters, an starting result, a processing function and a list of values. The processing function is then called with item of the list of values and the current result, which can be either the starting result or the return value of the previous call.
reduce in jq looks a bit different from other programming languages: The current item from the list of items must be aliased with the as $var expression ($var being a variable that get assigned the value of each item). Inside the brackets, before the semicolon comes the starting result, after the semicolon comes the processing function which can consist of any jq filter expression. In the processing function, the dot filter (.) does not refer to the current input object but to the current result. For the first input object, the current result is equal to the initial result. Whatever the processing function returns, becomes the new current result.
Here is a very nonsensical reduce, that just returns the initial result (“foo”):
jq -n 'reduce inputs as $obj ("foo"; . )' error.log The alias as$obj is used to access the current current item from the inputs function inside the processing function.
Another nonsensical reduce that ignores initial and current result and just returns the last input object would look like this:
jq -n 'reduce inputs as $obj ("foo";$obj )' error.log
Now back to our reduce example that mimicked the -s flag: reduce inputs as $obj ([]; . + [$obj]). The “plus” operator (+), when used on arrays, concatenates them into a new array. In the first iteration, the current result (accessed with the dot filter) is the empty array. It is concatenated with a single-item array, consisting of our current input object, $obj. In the next iteration, the next input object will be appended to the current result and so on. With your newfound knowledge you can create a processing function that counts up for each input object. Individual input values are not accessed yet, the function just counts up: jq -n 'reduce inputs as$obj (0; . + 1 )' error.log
Preparing for the next steps, that are about aggregating groups of errors and count their occurrence, let’s build an object as output instead of an integer:
jq -n 'reduce inputs as $obj ({"length": 0}; {"length": (.length + 1) } )' error.log The initial result is an object with a length property. Each time the processing function is called, a new object is created by accessing the length property of the current result. The calculation expression needs to be wrapped in brackets, to create new integer before the object is created. ## Counting error severities Your filter definitions will become longer and longer. To make them more readable and edit them, you can save the filter definition in a file and call jq like this: jq -n -f filter_definition.jq error.log Subsequent examples will only present the filter file filter_definition.jq, while the command line is always the same. The following filter file returns an object with counts for each severity: reduce inputs as$obj (
{};
. + {
($obj.severity): (.[$obj.severity] + 1)
}
)
{};
if $obj.severity == "E" then . + { ($obj.severity): (.[$obj.severity] + 1) } else . end ) Here you see how to use the if ... then ... else ... end construct. Since jq filters always have to return something, you’re not allowed to leave out the else part like in other programming languages. In our case, the current result object is returned unchanged if the severity does not match. ## Counting only specific messages The following filter file counts only the errors where the message contains the word “Widget”: reduce inputs as$obj (
{};
if ($obj.error.msg|test("Widget")) then . + { ($obj.severity): (.[\$obj.severity] + 1)
}
else
.
end
)
The test filter applies a regular expression to its input and returns a boolean. If the expression would read if test("Widget") then, the input for test would be the current result, which would also be a type mismatch because the current result is an object. But what actually should be checked is the current input object, which is why the pipe operator (|) is used. It “pipes” the error message as an input to the test filter. if needs a boolean value, so the whole test expression must be wrapped in brackets in order to be evaluated before the if is evaluated.
## Conclusion
Compared to trusty tools like wc, grep and awk for processing textual log files jq can seem daunting at first. Experienced programmers might whip out their favorite scripting language to do the job. But I hope this small tutorial has given you a starting point for your own analytic needs.
Example files for this entry can be found at https://gist.github.com/gbirke/84ed97eb208f09a5e3c1ccd0e6a2a89f.
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2018-10-23 05:53:54
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https://www.bartleby.com/questions-and-answers/16.suppose-that-the-dimensions-of-a-cylinder-change-at-constant-rates-the-radius-of-the-base-is-decr/2b37c8d2-76e4-41de-8665-f2cb0d8612fe
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# 16.Suppose that the dimensions of a cylinder change at constant rates: the radius of the base is decreasing at a rate of 1 cm/min, and its height is increasing at 8cm/min. At the moment when the radius is 5 cm and the height is 25 cm, at what rate are the volume and surface area of the cylinder changing?
Question
16.Suppose that the dimensions of a cylinder change at constant rates: the radius of the base is decreasing at a rate of 1 cm/min, and its height is increasing at 8cm/min. At the moment when the radius is 5 cm and the height is 25 cm, at what rate are the volume and surface area of the cylinder changing?
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2021-07-28 05:35:03
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http://blog.lujun9972.win/blog/2019/08/31/%E7%AC%91%E8%AF%9D%E7%90%86%E8%A7%A3%E4%B9%8Bfucking-magic/index.html
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暗无天日
=============>DarkSun的个人博客
笑话理解之Fucking magic
David Copperfield is doing his magic show and asks if anyone would like to show him a trick.
"I will", replies a guy in the audience, "but I'm going to need your wife Claudia and a table."
"Ok", says David and the guy gets on stage.
He then bends Claudia over the table, pulls down her knickers and starts f**king her from behind.
David is now very pissed off and says, "That isn't a trick!!!"
The guy just looks at David Copperfield and replies, "I know, it's fucking magic."
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2019-09-23 11:01:29
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https://www.nature.com/articles/s41598-021-04277-6?error=cookies_not_supported&code=681b12bf-15c9-4b62-a033-d9e0469ed2fd
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Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.
# Differential impact of government lockdown policies on reducing air pollution levels and related mortality in Europe
## Abstract
Previous studies have reported a decrease in air pollution levels following the enforcement of lockdown measures during the first wave of the COVID-19 pandemic. However, these investigations were mostly based on simple pre-post comparisons using past years as a reference and did not assess the role of different policy interventions. This study contributes to knowledge by quantifying the association between specific lockdown measures and the decrease in NO2, O3, PM2.5, and PM10 levels across 47 European cities. It also estimated the number of avoided deaths during the period. This paper used new modelled data from the Copernicus Atmosphere Monitoring Service (CAMS) to define business-as-usual and lockdown scenarios of daily air pollution trends. This study applies a spatio-temporal Bayesian non-linear mixed effect model to quantify the changes in pollutant concentrations associated with the stringency indices of individual policy measures. The results indicated non-linear associations with a stronger decrease in NO2 compared to PM2.5 and PM10 concentrations at very strict policy levels. Differences across interventions were also identified, specifically the strong effects of actions linked to school/workplace closure, limitations on gatherings, and stay-at-home requirements. Finally, the observed decrease in pollution potentially resulted in hundreds of avoided deaths across Europe.
## Introduction
COVID-19 disease is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This infectious disease has spread worldwide placing enormous pressure on national health systems since it can cause hospitalization1 and lead to death2. The first official outbreak was reported in Wuhan (China) in December 2019 and, as of January 4, 20223, the virus is already responsible for 5.46 million deaths worldwide and 1.54 million across Europe. Several local and national policy interventions have been implemented to prevent the transmission of SARS-CoV-2, such as social distancing, stay at home requirements, international travel controls, and non-essential business closures4,5. As a consequence of this unique global coordinated response, several urban areas across the world experienced an abrupt drop in air pollution levels6. Given the substantive evidence on the short-term effects of air pollution on health, recent studies have suggested that the decrease in exposure of entire populations likely resulted in a reduction in excess mortality and morbidity in different location worldwide7,8,9,10.
Several studies explored different approaches to assess air pollution changes during the first COVID-19 lockdown. In Europe, Ordóñez and colleagues11 used the European Environment Agency's ground monitoring database12 to estimate the NO2 and O3 changes from mid-March to April 2020 compared to 2015–2019. They used a generalised additive model to weather-normalise the daily maximum 1 h mean nitrogen dioxide (NO2) and the 8 h mean Ozone (O3). They identified an increase of around 10–22% in O3 concentrations from northwestern to central Europe based on urban background monitors. Venter et al.13 collected satellite and ground station data to estimate air pollution differences between January and May 2020 and a baseline period (2017–2019) in 34 countries. They used a multiple linear regression model to weather-normalise during lockdown period surface concentrations of NO2 and particle matter (PM) with an aerodynamic diameter smaller than 2.5 µm (PM2.5). They found a reduction in daily mean NO2 and PM2.5 of 60% and 31%, respectively, with a small increase in ozone (O3) of 4%. Following up, Venter et al.14 used the estimated changes in pollution to compute the expected reduction in excess mortality and morbidity, reporting a total of 49,900 excess deaths and 89,000 pediatric asthma emergency room visits avoided during the lockdown. Giani et al.15 assessed the health impact of daily mean PM2.5 concentrations decline in Europe and China by integrating ground station data with a chemical transport model. They simulated the effect of the first COVID-19 lockdown (short-term) on PM2.5 concentrations and four emission scenarios of future economic recovery (long-term). In Europe, they found an estimated 2190 short-term avoided deaths (during February–May) and, depending on the economic recovery path, a number of preventable deaths in the long term ranging from 13,600 to 29,500.
Gkatzelis et al.16 critically reviewed more than 200 papers and acknowledged the significant effects of meteorological conditions on pollutant concentrations as well as the importance to account for it in the statistical models together with emission trends and atmospheric chemical interactions. They also reported that the majority of publications did not weather-normalise the concentration of pollutants. These steps are relevant because air quality conditions are determined in part by changes in weather and in part by emissions of pollutants from human activities. At different layers of the atmosphere, these two elements will drive a complex package of physical and chemical non-linear interactions17,18, determining the spread and concentrations of each pollutant. This makes it complex to conduct simple pre-post comparisons between concentrations in 2020 and previous years. For instance, Barré et al.19 demonstrated how much the estimated reduction in NO2 levels can vary significantly using simple pre-post or weather-normalised comparisons as well as different data sources. For example, they weather-normalised all estimates and the results demonstrated a large variability on the average reductions from satellite (− 23%) and ground monitors observations (− 43%), and air quality models (− 32%). This study also identified that several previous studies defined the lockdown scenario as a fixed period of low air pollution levels. However, several policy responses were taken by governments at different dates, likely resulting in varying intensity and timing of the reduction in air pollution. More importantly, this simplistic definition prevents the quantitative assessment and comparison of several policy interventions and in particular their differential impact in reducing concentrations of different types of air pollutants.
This study aims first to address all significant effects reported in the literature (i.e. weather correction, emission trends, atmospheric chemistry, and temporally-variant lockdown period of air pollution levels), then to analyse the impact of government responses in reducing the concentration of four pollutants [NO2, O3, PM2.5, and PM < 10 µm (PM10)] across 47 European cities (listed in Table 1), and finally to report the related preventable mortality for 46 locations (see “Data and methods”). This study contribute original evidence to the literature by estimating the decline of air pollution levels across Europe in association with the strictness of specific lockdown policies. This assessment will make use of the Copernicus Atmosphere Monitoring Service (CAMS)20 operational air quality framework of forecast model ensemble applied under two temporally-variant emission scenarios, representing a business-as-usual (BAU) and lockdown settings, over the exact same period of 2020 (February–July)21. The use of innovative data sources and methodological approaches will provide a quantitative assessment of the roles of specific lockdown policy interventions in reducing pollution levels and associated short-term mortality during the study period.
## Data and methods
### Data
#### Design setting
This study originally selected 50 cities among the largest in Europe to represent most of the countries and populations (Table 1)4. Among these 50, three were excluded (Podgorica—Montenegro, Skopje—Moldova, and Valletta—Malta) because of the absence of government response data. This study reported the results of the government responses to lower air pollution for 47 cities; however, the excess deaths were estimated for 46 cities since the mortality rate for Pristina (Kosovo) was not available on the Eurostat database22. The study period ranges from 1st of February to 31st of July 2020 and roughly represents the first wave of COVID-19 pandemic in Europe, with a short initial period characterised by the absence of government responses, followed by a strict implementation and then partial relaxation of lockdown policies. For this period and cities, concentrations of four air pollutants (NO2, O3, PM2.5, and PM10) were extracted from numerical forecast models (see below) under two emission scenarios: BAU and Lockdown21.
#### Numerical forecast model dataset
CAMS is one of the services that form Copernicus, the European Union's Earth observation programme providing quality-controlled information related to air pollution via chemical transport models that are driven by a single numerical weather prediction model. An ensemble of six state-of-the-art chemistry-transport numerical forecast models (Table A3) included in the CAMS continuous air quality monitoring service has been used to simulate air pollution concentrations under the two emission scenarios. The BAU scenario considers no government restrictions, with air pollution emissions running at their default inventory demand. The BAU emissions are obtained from the CAMS-REG-APv4.2 gridded inventory (0.1 × 0.05°)23 constructed by Kuenen et al.24, which is largely based on the official reported emission data from individual countries in Europe to the Centre on Emission Inventories and Projections (CEIP) at European Monitoring and Evaluation Programme (EMEP) for each source category. The Lockdown scenario is based on daily-, sector-, pollutant- and country-dependent emission reduction factors determined by the Barcelona Supercomputing Centre21. The rationale for the reduction factors was supported by many relevant activity-based and open-access observations, for example, Google mobility reports25. The CAMS-REG-APv4.2 inventory was combined with the emission reduction factors in order to model dynamic emission reductions for each sector and country in the Lockdown scenario. The base year of the CAMS-REG-APv4.2 emissions used in the two scenarios was 2017, which was the most recent year available at the time of the study. Meteorological forcing that was used to generate the simulation remained identical, enabling a consistent comparison between the two scenarios. This CAMS product provides hourly concentrations of the ensemble median of the six models at the surface level of each pollutant across Europe in a regular latitude–longitude grid of 0.1° (approx. 10 × 10 km2). This study extracted for each of the 47 cities daily averages of Lockdown–BAU difference for NO2, PM2.5, and PM10 and daily maximum 8 h mean for O3.
#### Oxford coronavirus government response tracker
The Oxford Coronavirus Government Response Tracker (OxCGRT)4 dataset systematically collects information on governments responses to the COVID-19 pandemic. This global dataset is updated daily with information translated into 19 individual policy measures that are classified in four groups: containment and closure policies (C), economic policies (E), health system policies (H) and miscellaneous policies (M). These individual measures are coded as an integer between 0 (no government measure) and a maximum level that depends on the measure (usually between 2 and 4). The OxCGRT dataset also proposes several thematic indices combining subsets of the 19 measures.
This study focused on a quantitative measure of the strictness of the lockdown interventions, the Stringency Index (SI). This measure is constructed as the mean of nine policy measures: all eight C policies and the H1 policy that records public information campaigns (Table A14). The SI is computed as the mean of the standardized policy measures (between 0 and 1), so that each policy measure contributes equally to the SI, independently from its number of levels. The SI is then rescaled to have values between 0 (no response) and 100 (maximum response in every possible policy measure).
#### Health impact assessment
For the health impact assessment, estimates of relative risk (RR) of mortality associated with short-term exposure to each pollutant were collected from published multi-country studies for NO226, O38, PM109 and PM2.59. In addition, city-specific variables potentially related to differential pollution levels, specifically population size, NDVI (greenness), and built-up area, were collected for the year 2015 from the Global Human Settlement Urban Centres Database (GHS-UCDB)27. Finally, city-specific crude all-cause mortality rates for 2015 were extracted from Eurostat22.
### Statistical analysis
The statistical analysis follows three main steps: (1) estimation of the association between SI and changes in pollution between Lockdown and BAU scenarios, (2) estimation of the specific impact of each sub-policy measure on the pollution change, and (3) health impact assessment with the quantification of avoided deaths due to short-term exposure to air pollution. Each of these steps was performed independently for each of the four pollutants. The analysis was performed in R-4.0.328 with the addition of the integrated nested Laplace approximation (INLA) package29.
#### Association between Stringency Index and pollution difference
The first step of the study modelled the association between changes in air pollution and SI through a spatially structured Bayesian non-linear mixed effect model, expressed by Eq. (1):
$${y}_{it}=f\left({x}_{it};{\varvec{\beta}}+{{\varvec{b}}}_{i}\right)+{{\varvec{\gamma}}}_{1i}{DOW}_{t}+{\gamma }_{2}NDV{I}_{i}+{\gamma }_{3}{BuiltUp}_{i}+{\epsilon }_{it}$$
(1)
where $${y}_{it}$$ represents the pollutant-specific change (Lockdown-BAU) for city i and day t; $${x}_{it}$$ is the daily SI for the city i; DOW represents a factor for day-of-week with city-specific coefficients $${{\varvec{\gamma}}}_{1i}$$, while NDVI and BuiltUp area are city-specific indicators with related coefficients $${\gamma }_{2}$$ and $${\gamma }_{3}$$. The $${{\varvec{\gamma}}}_{1i}$$ is estimated as city-specific since the DOW effect magnitude varies from city to city. $${\epsilon }_{it}$$ is an unstructured Gaussian residual. Note that the intercept is removed from the model since no pollutant change ($${y}_{it}=0$$) is expected in the initial phase of no government response.
The nonlinear term $$f\left({x}_{it};{\varvec{\beta}}+{{\varvec{b}}}_{i}\right)$$ is expanded through natural splines with four degrees of freedom and three knots placed at the 25, 50, and 75% quantiles. $${\varvec{\beta}}$$ is thus a four-dimensional vector representing fixed effect and $${{\varvec{b}}}_{{\varvec{i}}}$$ are four-dimensional vectors representing city-specific deviations from the fixed effects $${\varvec{\beta}}$$. For each of the four coefficients in $${{\varvec{b}}}_{i}$$, a spatial structure is added through a stochastic partial differential equation (SPDE) approach30. Specifically, a Matérn covariance function was applied with penalized complexity prior as defined by Franco-Villoria et al.31.
The model in Eq. (1) is fitted through the INLA procedure for Bayesian estimation32. Uninformative flat priors were used for all unstructured coefficients. In the main manuscript body, this study reports posterior means and 95% credible intervals of predicted pollutant changes for a range of SI between 0 and 80%, as higher levels were not observed in most cities.
#### Impact of specific policy measures
The second step of the study assessed the impact of specific policy measures. Each policy indicator used to compute the SI was included as a new variable in the model of Eq. (1), generating the new following Eq. (2):
$${y}_{it}=\left(\mathrm{\alpha }+{a}_{\mathrm{i}}\right){z}_{\mathrm{it}}+f\left({x}_{it}^{^{\prime}};{\varvec{\beta}}+{{\varvec{b}}}_{i}\right)+{{\varvec{\gamma}}}_{1i}{DOW}_{t}+{\gamma }_{2}NDV{I}_{i}+{\gamma }_{3}{BuiltUp}_{i}+{\epsilon }_{it}$$
(2)
where $${z}_{it}$$ is the policy measure with associated fixed and city-specific effects $$\alpha$$ and $${a}_{i}$$, and $${x}_{it}^{^{\prime}}$$ is the SI measure with $${z}_{it}$$ removed. We standardize $${z}_{it}$$ so that it takes zero when the policy is not implemented and one at its maximum level of stringency. The coefficient $$\left(\mathrm{\alpha }+{a}_{\mathrm{i}}\right)$$ then represents the effect of the policy’s maximum level. All other components in Equation Eq. (2) are the same as their counterparts in Equation Eq. (1). As for the analysis of the full SI, city-specific policy coefficients $${a}_{i}$$ are also spatially structured with a Matérn covariance function and corresponding penalized complexity priors. The model in Eq. (2) is also fitted by INLA. “Results” section reports posterior means of $$\alpha$$ for each pollutant and policy measure.
### Estimating the excess deaths attributable to changes in air pollution levels
Given the estimates of the association between each pollutant and mortality $$\xi$$, daily mortality burdens are computed as:
$${d}_{it}={m}_{i}\times {p}_{i}\times (1-{e}^{-\widehat{\xi }{y}_{it}})$$
(3)
where $${m}_{i}$$ is the crude death rate, $${p}_{i}$$ the population of city $$i$$ and $${y}_{it}$$ the observed pollutant difference. $$\widehat{\xi }$$ is the pollutant-specific effect on mortality gathered from the literature8,9,26. The estimated values of $${d}_{it}$$ are then summed by city to obtain total city-specific mortality burdens for the period of February to July. To compare results, Table A4 reports both the total deaths by city and the excess deaths under the BAU scenario by pollutant and city, both during February and July 2020.
The uncertainty assessment of the mortality burdens was obtained by parametric Monte-Carlo simulations. A total of 1000 values were sampled from a Gaussian distribution with mean $$\widehat{\xi }$$ and standard deviation derived from the confidence intervals reported in the literature, and for each simulated coefficient, compute the mortality burden. Empirical confidence intervals are then obtained by computing the percentile 2.5th and 97.5th of a sample of 1000 iterations of computed mortality burdens.
## Results
### Analysis of changes in air pollution levels across Europe
Several of the atmospheric models that are part of CAMS regional air quality forecast system were used to simulate the concentrations of the four pollutants under two scenarios, defined as ‘Lockdown’ and ‘BAU’ during the same period of 2020 (February–July). Their differences were used in this study to estimate city-specific changes in the daily concentration of each pollutant type. Figure 1 displays the time series of the change in levels of the daily mean of NO2 and PM and daily maximum 8 h mean for O3 in each of the 47 cities (listed in Table 1) and their average. Plots of NO2 and PM indicate that their concentrations started to plummet during the first half of March, when the government responses were first implemented across the majority of the European cities. Differences across cities can be related to the different timing of lockdown policy implementations, as well as variation in strictness and potential effects of the policies. For instance, Milan (Italy) shows an earlier decline compared to the other cities, until the NO2 concentrations dropped to their minimum around mid-March. In contrast, London (United Kingdom) experienced a noticeable decrease only in the second half of March. Stockholm (Sweden) had its air pollution levels less affected during the study period due mostly to the less stringent interventions from the government. After the strong decline in March/April, all cities experienced an attenuation in their NO2 and PM changes, but still keeping their levels lower than in the BAU scenario. Concentrations of daily maximum O3 show a different pattern compared to the other three pollutants. The relative changes are very limited throughout the period with a slight increase up to the end of April, followed by very limited reductions for the remainder of the period. The seasonal variability of O3 is very different compared to other pollutants because of its specific photochemical sensitivity which leads to enhanced formation in the summer season, while reductions in nitrogen oxides emissions (NOx, combination of nitrogen oxides NO and NO2) can lead to an increase of O3 as a result of reduced titration and/or depending on the mix of O3 production precursors (NOx and VOCs). Titration is of particular concern close to emission sources, at night, or in winter, in part due to conditions of increased atmospheric stability, but it can occur over a wide range of conditions. The specific temporal pattern of O3 shown in Fig. 1 is therefore likely attributed to the transitioning between winter and summertime chemistry in the April/May period.
### Quantifying the effect of lockdown strictness
Changes in pollution levels were then linked with measures of government policy responses to the pandemic, collected from the OxCGRT4 (Table A1). In addition to offer a systematic definition of lockdown measures, the database provides quantitative indices of strictness across countries and periods. Specifically, an overall measure is offered by the SI (ranging from 0 to 100%), a summary of nine indicators related to containment, closure, and health policies. Table 1 reports the maximum daily SI score across the sample of cities, while Figure A1 in the supplementary material illustrates the average and city-specific daily series. As expected, there is a common temporal pattern in the strictness of the implemented policies, although with noticeable differences across cities. Until early March, many cities experienced an increase in SI level by modest steps when an abruptly jump to an SI level around 75% was seen for most of the locations, and by mid-May, the SI levels were then generally going down by large steps (Figure A1). Belgrade (Serbia) was the only city having the maximum government response index (100%) while Stockholm (Sweden) reached only 46.3% (Table 1).
A quantitative estimate of the association between the strictness of lockdown policies and decrease in air pollution was obtained by relating daily Lockdown–BAU differences to SI measures in each of the 47 cities. The association was estimated based on a Bayesian hierarchical spatio-temporal model implemented using the INLA method. The model used daily time series of change in each pollutant as the outcome and the SI as a predictor, while controlling for the day of the week, normalised difference vegetation index (NDVI), and built-up area. This advanced methodology allowed us to flexibly model city-specific non-linear exposure–response relationships and to account for spatial correlation across locations in Europe.
Figure 2 displays the results as average and city-specific estimated change in concentrations across the SI range. On average, results indicate an inverse association for all cities, showing a decrease when increasing the strictness of government policies. This decrease is mild for low values of SI but sharpens at higher values. The decrease was substantial for NO2, while the PM shows a weaker effect. Results for O3 suggest a lower effect at very high SI ranges. The different relationship with O3 can be influenced by the more complex temporal pattern of this pollutant and the role of seasonal factor that determine its concentration. The wider 95% credible interval seen between 20 and 40% SI in Fig. 2 is likely due to the sparse data within this range, as most of the cities have recorded levels jumping from around 0 to very high values.
Figure 3 displays maps of changes in each pollutant predicted with an 80% SI score (a value reached in most of the cities) across the European region. The actual estimates are reported in full in Table A2, together with 95% credible limits. The maps suggest a clear geographical pattern, although with some differences between pollutants. The strongest effect on NO2 for an 80% SI score was seen in Athens (Greece), presenting a Lockdown–BAU difference around − 10.2 µg/m3 (− 10.7; − 9.7) (Table A2). London shows strong effects, with a increase for O3 of 2.9 µg/m3 (1.9; 4.0) and a decrease of − 9.0 µg/m3 (− 10.1; − 7.9), − 2.6 µg/m3 (− 3.0; − 2.2), and − 2.9 µg/m3 (− 3.4; − 2.5) for NO2, PM2.5, and PM10, respectively. A clear latitudinal gradient is found for O3, because of its specific photochemical formation, where titration effects are more pronounced in northern NOx saturated areas such as the Benelux region, whereas reductions are found around the Mediterranean.
The third part of this study focused on investigating the contribution of individual policy indicators used to compute the SI on the reported change in air pollutants. The strictness levels of each indicator are described in Table A1. In this part, separate models were fitted to assess policy indicators individually, using each of them as a predictor along with the SI computed without it, thus disentangling their respective contribution. Results reported in Fig. 4 show that decreases in NO2 were mostly linked with policies that limited the daily commute travels, such as C1 (school closing), C2 (workplace closing), C3 (cancel public events), and C6 (stay at home requirements). Results for PM2.5 and PM10 show a consistent pattern, although with lower effects. C1 and C3 policies had a strong effect in increasing O3 concentrations during lockdown scenario (with similar but more uncertain evidence for C2 and C6), while C4 (restrictions on gatherings) contributed to lower O3 levels. Interesting to note is that some policies, such as C7 (restriction on internal movement), C8 (international travel controls), and H1 (public information campaigns) seemed to have little impact on pollution concentrations.
### Avoided mortality due to short-term exposure to air pollution
The fourth and last part was to estimate the number of premature deaths avoided due to the decline in air pollution levels associated with the government responses. The total deaths were estimated for each city using exposure–response relationships reported in recent literature for each pollutant and the observed changes in daily concentration, independently of the SI levels. Results are reported in Table 1, indicating a total number of avoided deaths of 486, 37, 175, and 134 for NO2, O3, PM2.5, and PM10 across the 46 cities [except Pristina (Kosovo)]. Paris (France), London, and Barcelona (Spain), and Milan are within the top six cities with the highest number of avoided deaths for NO2 and PM (Table 1). However, the highest excess deaths for O3 were found in London and Paris.
## Discussion
The response of governments to curb the COVID-19 pandemic spread offers an unprecedented case study to assess a range of interventions to reduce anthropogenic emissions from several sectors (i.e. road transport, energy industry, manufacturing industry, commercial and public services, shipping, and aviation). In this context, this study contributes to the literature in many aspects. First, it provides an accurate representation of air pollution decline during the first pandemic phase that was simulated by comparing lockdown versus BAU scenarios using an ensemble of six state-of-the-art numerical forecast models from the CAMS. The changes in NO2, O3, PM2.5, and PM10 were then separately regressed against the SI levels (i.e. standardized lockdown measures), thus providing quantitative estimates of the association with the strictness of the policies. The estimation was performed using a spatio-temporal Bayesian non-linear mixed effect model. This advanced methodological approach can estimate flexible relationships across cities while accounting for spatial dependencies. The main original aspect of this study is the assessment of multiple indices related to individual lockdown policies, in order to evaluate their comparative role in determining changes in air pollution. Finally, a quantitative health impact assessment was performed for the period of February–July of 2020, estimating the avoided/excess deaths due to the air pollution changes in 46 of the 47 European cities.
It has been reported by several space33 and environment agencies34 that air quality satellites and ground-based monitors captured an abrupt drop in air pollution levels in several cities during the first COVID-19 lockdown. The literature includes many studies which have compared pollutant concentrations before and after the start of the lockdown or comparing the year 2020 to another. These procedures can neither account for the influence of weather variability nor account for complex atmospheric processes and chemical interactions of multiple pollutants and precursors. This study innovates from published approaches by using CAMS20, an ensemble atmospheric model, which simulates pollutant concentrations in two scenarios during the exact same period and identical weather conditions. The quality of the CAMS regional production is closely monitored with regular quality control35 and the models are also used in support of European air quality policies36. The results demonstrated that NO2 was the pollutant with the largest decline (Fig. 1) displaying a reduction above 50% for Spain (Madrid), Portugal (Lisbon), France (Lyon and Paris), and Italy (Milan, Turin, and Rome). Although satellite, ground-observations, and modelled-based estimates demonstrate large discrepancies, Barré and colleagues19 using weather-normalised estimates found a consistent decrease of NO2 surface concentrations across Europe. They also highlighted Spanish, Italian and French cities as the locations with the largest effect (around 50–60%). The main reason for NO2 noticeable drop is because its main emission contributor (road transport) was the most affected sector by government restrictions. This study presented a smaller mean reduction in PM2.5 of 0.60 µg/m3, compared to Giani et al.15 (1.82 µg/m3) using a shorter period (from 21st February to 17th May). However, they described PM2.5 peaks of − 6.6 µg/m3 while this study found higher PM2.5 change extremes (i.e., − 15.30 µg/m3). The PM2.5 reductions are likely associated with policy interventions also in the energy, manufacturing industry, and commercial sectors; however, a small increase should be considered from residential activities due to stay-at-home requirements. In contrast, ground-level O3 concentrations increased slightly in urban locations across Europe at the beginning of the lockdown (April), primarily as a result of the absence or a lower titration of O3 by NOx emissions from industrial and motor vehicle activities37. Ordóñez and colleagues11 identified higher O3 concentration during March–April 2020 compared to March–April 2015–2019 mostly over the northwestern area (i.e. Benelux region and the United Kingdom). They emphasized the role of meteorological variability in this comparison of an individual year (2020) with a 4-year average of the previous period. During March–April 2020 over the same area, this study also detected a high increase in O3 production compared to the BAU scenario. However, thanks to the use of a fixed meteorological year in our approach (i.e., both Lockdown and BAU scenarios performed during March–April 2020), this study can conclude that this O3 increase was mainly due to the reduced NOx concentrations and exclude meteorological factors. On the other hand, Ordóñez and colleagues results on the decrease in O3 changes over Portugal and Spain contrasted with the increasing O3 changes found in this study.
To our knowledge, this is the first study that quantifies the decline of air pollution levels across Europe in association with the strictness of specific lockdown policies. This analysis is based on flexible statistical techniques to capture effects across the range of standardised policy indices. The findings also revealed clear evidence of non-linear relationships, with stronger changes at higher SI values, indicating that stricter lockdown policies were more effective in decreasing air pollution. Extending the assessment to individual policies, this study revealed that the reduction in pollutant’s concentration cannot be attributed to all policies included in the SI. Government actions linked to school/workplace closure, limitations on gatherings and stay-at-home requirements had the greatest impact on reducing NO2 concentrations. This is likely explained by their effectiveness in limiting local mobility, therefore, reducing the large contribution of road transport emissions to the total NOx primary emissions38. Despite the large drop in road transport emissions (one of the primary and secondary PM precursor emission sources), PM levels were reduced more modestly since they are also produced by natural sources. The secondary component of PM, which can respond non-linearly to emissions, may also be behind this moderate response, while some cities experienced a slight PM increase due the stay-at-home requirements which can stimulate the increase of residential wood combustion. However, even if wood combustion represents over half of PM primary emissions39, its contribution to the total PM emissions was very limited during the first lockdown wave40 due to the season period and its usage purpose (indoor heating) across Europe. The results also demonstrated that policies banning national movements and international travels seem less successful in lowering air pollution. This restriction relates mainly to emissions from the aviation sector, which usually have a low contribution to the overall urban air quality levels. These findings can contribute to the definition of future European strategies and priorities on the design and implementation of policies for reducing air pollution levels in urban areas. As a public health measure, this reduction experienced across Europe during February-July of 2020 could have prevented hundreds of deaths associated with short-term exposure to air pollution. Based on independent estimates for NO2, O3, PM2.5, and PM10, it could have avoided 486, 37, 175, and 134 deaths (Table 1) compared to 2,573, 5,190, 2,441, and 2,186 excess deaths estimated under a BAU scenario (Table A4) respectively, over the same period.
This study also faced some limitations that must be acknowledged. This study did not investigate the following lockdown waves across Europe after July 2020 because the concentration of pollutants for the lockdown scenario were provided only between February and July 2020. The strictness of government policies (expressed by the SI) corresponds to the country’s response rather than city-specific interventions. The wide confidence intervals in Fig. 4 suggest that there is still important uncertainty about the results, stemming from the important collinearity between the individual policies that were roughly implemented at the same time. Therefore, such evidence should not be straightforwardly used to define specific public policies since it must be based on a broader assessment of the literature and not on the results of a single study. In the health impact assessment, this study applied the pollutant’s exposure–response relationship representing the average value reported in the referenced papers; therefore, not accounting for potential heterogeneity in the associated health risks across cities. The excess deaths also should be interpreted with caution, since all locations experienced a decrease in concentrations for many pollutants at the same period, with the NO2-, O3-, PM10-, and PM2.5-related avoided deaths partially overlapping. However, previous studies reported41 a low risk of double counting, with similar associations between pollutant and deaths from single-pollutant (e.g. NO210) and two-pollutant concentration–response models (e.g. NO2 and PM2.59). Another important point to acknowledge is that the preventable deaths reported in this study were estimated using outdoor air pollution levels, while lockdown conditions forced most of the people to spent most of their time indoors. Finally, this study did not account for cause-specific deaths or other health outcomes, as well as long-term mortality risks. This will be likely addressed in future research.
To conclude, this study assessed the association between standardised measures of global and individual policies responses to the COVID-19 pandemic with changes in air pollution and short-term premature mortality in Europe. These findings provide evidence on the effectiveness of government restrictions and target policies for reducing air pollution concentrations in urban areas and demonstrate the public health benefits of reducing human exposure to high air pollution levels across Europe.
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## Acknowledgements
This research had free and open access to all data sources. The work described in this paper has received funding from European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf the European Union through commercial contract Ref. CAMS_95p. Several CAMS Regional Models of the CAMS_50 Service contributed to the present work (CHIMERE, LOTOS-EUROS, MINNI, MOCAGE, MONARCH, SILAM) under CAMS_71 coordination. CAMS_COP066 service provided the lockdown emissions information. O.J. and M.G. thankfully acknowledge the computer resources at Marenostrum and the technical support provided by Barcelona Supercomputing Center (RES-AECT-2020-1-0007). SILAM model runs was also funded by Finnish Academy GLORIA project (No310372). The study was supported by the European Union’s Horizon 2020 Project Exhaustion (Grant ID: 820655).
## Author information
Authors
### Contributions
Conceptualization, R.S., P.M., and A.G.; methodology, R.S., P.M., A.G., M.B., and C.F.; formal analysis, R.S., P.M., and A.G.; data curation, R.S., P.M., A.M.V.C., F.S., J.B., V.H.P., A.C.; emission data, M.G., O.J.; CAMS regional models, J.D., M.A., R.K., F.C., J.A., M.G., O.J., B.R., A.C.; writing–original draft preparation, R.S.; writing–review and editing, all authors; visualization, R.S. and P.M.; project administration, R.S.; funding acquisition, R.S. and A.G. All authors have read and agreed to the published version of the manuscript.
### Corresponding author
Correspondence to Rochelle Schneider.
## Ethics declarations
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Schneider, R., Masselot, P., Vicedo-Cabrera, A.M. et al. Differential impact of government lockdown policies on reducing air pollution levels and related mortality in Europe. Sci Rep 12, 726 (2022). https://doi.org/10.1038/s41598-021-04277-6
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Fence It
Stage: 3 Challenge Level:
If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?
Framed
Stage: 3 Challenge Level:
Seven small rectangular pictures have one inch wide frames. The frames are removed and the pictures are fitted together like a jigsaw to make a rectangle of length 12 inches. Find the dimensions of. . . .
Intersecting Circles
Stage: 3 Challenge Level:
Three circles have a maximum of six intersections with each other. What is the maximum number of intersections that a hundred circles could have?
Take Ten
Stage: 3 Challenge Level:
Is it possible to remove ten unit cubes from a 3 by 3 by 3 cube made from 27 unit cubes so that the surface area of the remaining solid is the same as the surface area of the original 3 by 3 by 3. . . .
Dissect
Stage: 3 Challenge Level:
It is possible to dissect any square into smaller squares. What is the minimum number of squares a 13 by 13 square can be dissected into?
Wrapping Presents
Stage: 2 Challenge Level:
Choose a box and work out the smallest rectangle of paper needed to wrap it so that it is completely covered.
Trice
Stage: 3 Challenge Level:
ABCDEFGH is a 3 by 3 by 3 cube. Point P is 1/3 along AB (that is AP : PB = 1 : 2), point Q is 1/3 along GH and point R is 1/3 along ED. What is the area of the triangle PQR?
Stage: 2 Challenge Level:
How can you arrange the 5 cubes so that you need the smallest number of Brush Loads of paint to cover them? Try with other numbers of cubes as well.
Two Squared
Stage: 2 Challenge Level:
What happens to the area of a square if you double the length of the sides? Try the same thing with rectangles, diamonds and other shapes. How do the four smaller ones fit into the larger one?
An Unusual Shape
Stage: 3 Challenge Level:
Can you maximise the area available to a grazing goat?
Cuboids
Stage: 3 Challenge Level:
Find a cuboid (with edges of integer values) that has a surface area of exactly 100 square units. Is there more than one? Can you find them all?
Tied Up
Stage: 3 Challenge Level:
In a right angled triangular field, three animals are tethered to posts at the midpoint of each side. Each rope is just long enough to allow the animal to reach two adjacent vertices. Only one animal. . . .
Stage: 3 Challenge Level:
How many different symmetrical shapes can you make by shading triangles or squares?
All in the Mind
Stage: 3 Challenge Level:
Imagine you are suspending a cube from one vertex (corner) and allowing it to hang freely. Now imagine you are lowering it into water until it is exactly half submerged. What shape does the surface. . . .
World of Tan 4 - Monday Morning
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of Wai Ping, Wah Ming and Chi Wing?
The Old Goats
Stage: 3 Challenge Level:
A rectangular field has two posts with a ring on top of each post. There are two quarrelsome goats and plenty of ropes which you can tie to their collars. How can you secure them so they can't. . . .
Dodecamagic
Stage: 2 Challenge Level:
Here you see the front and back views of a dodecahedron. Each vertex has been numbered so that the numbers around each pentagonal face add up to 65. Can you find all the missing numbers?
Nine-pin Triangles
Stage: 2 Challenge Level:
How many different triangles can you make on a circular pegboard that has nine pegs?
World of Tan 11 - the Past, Present and Future
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of the telescope and microscope?
Isosceles Triangles
Stage: 3 Challenge Level:
Draw some isosceles triangles with an area of $9$cm$^2$ and a vertex at (20,20). If all the vertices must have whole number coordinates, how many is it possible to draw?
World of Tan 14 - Celebrations
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of Little Ming and Little Fung dancing?
World of Tan 1 - Granma T
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of Granma T?
World of Tan 3 - Mai Ling
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of Mai Ling?
Little Boxes
Stage: 2 Challenge Level:
How many different cuboids can you make when you use four CDs or DVDs? How about using five, then six?
Overlapping Again
Stage: 2 Challenge Level:
What shape is the overlap when you slide one of these shapes half way across another? Can you picture it in your head? Use the interactivity to check your visualisation.
Tetra Square
Stage: 3 Challenge Level:
ABCD is a regular tetrahedron and the points P, Q, R and S are the midpoints of the edges AB, BD, CD and CA. Prove that PQRS is a square.
Triangular Faces
Stage: 2 Challenge Level:
This problem invites you to build 3D shapes using two different triangles. Can you make the shapes from the pictures?
Redblue
Stage: 2 Challenge Level:
Investigate the number of paths you can take from one vertex to another in these 3D shapes. Is it possible to take an odd number and an even number of paths to the same vertex?
Putting Two and Two Together
Stage: 2 Challenge Level:
In how many ways can you fit two of these yellow triangles together? Can you predict the number of ways two blue triangles can be fitted together?
Muggles Magic
Stage: 3 Challenge Level:
You can move the 4 pieces of the jigsaw and fit them into both outlines. Explain what has happened to the missing one unit of area.
Midpoint Triangle
Stage: 2 Challenge Level:
Can you cut up a square in the way shown and make the pieces into a triangle?
Cubes Within Cubes Revisited
Stage: 3 Challenge Level:
Imagine starting with one yellow cube and covering it all over with a single layer of red cubes, and then covering that cube with a layer of blue cubes. How many red and blue cubes would you need?
Fractional Triangles
Stage: 2 Challenge Level:
Use the lines on this figure to show how the square can be divided into 2 halves, 3 thirds, 6 sixths and 9 ninths.
World of Tan 21 - Almost There Now
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outlines of the lobster, yacht and cyclist?
World of Tan 20 - Fractions
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outlines of the chairs?
World of Tan 22 - an Appealing Stroll
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of the child walking home from school?
World of Tan 24 - Clocks
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outlines of these clocks?
Counting Cards
Stage: 2 Challenge Level:
A magician took a suit of thirteen cards and held them in his hand face down. Every card he revealed had the same value as the one he had just finished spelling. How did this work?
World of Tan 8 - Sports Car
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of this sports car?
World of Tan 19 - Working Men
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of this shape. How would you describe it?
Cubic Conundrum
Stage: 2 Challenge Level:
Which of the following cubes can be made from these nets?
Playground Snapshot
Stage: 2 and 3 Challenge Level:
The image in this problem is part of a piece of equipment found in the playground of a school. How would you describe it to someone over the phone?
Cutting a Cube
Stage: 3 Challenge Level:
A half-cube is cut into two pieces by a plane through the long diagonal and at right angles to it. Can you draw a net of these pieces? Are they identical?
World of Tan 9 - Animals
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of this goat and giraffe?
World of Tan 25 - Pentominoes
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outlines of these people?
World of Tan 26 - Old Chestnut
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of this brazier for roasting chestnuts?
Zooming in on the Squares
Stage: 2 and 3
Start with a large square, join the midpoints of its sides, you'll see four right angled triangles. Remove these triangles, a second square is left. Repeat the operation. What happens?
World of Tan 5 - Rocket
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of the rocket?
World of Tan 7 - Gat Marn
Stage: 2 Challenge Level:
Can you fit the tangram pieces into the outline of this plaque design?
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2015-07-31 21:37:34
|
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|
http://www.physicsforums.com/showthread.php?t=541396&page=3
|
## Transistor question-biasing
I tried to explain the feedback in post#2 but I don't think I did a good job and don't know how to explain it better. Remember it is the voltage between the base and the emitter that govern the collector current, not just the base voltage. The emitter resistor serve as the feedback to stabilize the transistor so it does not drift that much. Hope someone else can write it better to explain to you.
BTW, nobody claim this 3 legged animal is easy!!! Take your time, keep asking question here and people will try to answer. One book that I studied this subject is by Malvino. It is the easiest and the best book on transistor I've seen.
Quote by yungman I tried to explain the feedback in post#2 but I don't think I did a good job and don't know how to explain it better. Remember it is the voltage between the base and the emitter that govern the collector current, not just the base voltage. The emitter resistor serve as the feedback to stabilize the transistor so it does not drift that much. Hope someone else can write it better to explain to you. BTW, nobody claim this 3 legged animal is easy!!! Take your time, keep asking question here and people will try to answer. One book that I studied this subject is by Malvino. It is the easiest and the best book on transistor I've seen.
You really made me laugh with this 3 legged animal hahahahah.
Don't worry. I truly appreciate yours, and any other expert help that I can get here. Because, to be honest, today there are few people that are willing to even try to explain something to you.
People like You, Jim and countless others, make the students life more easy, where new concepts are not that naive.
I will definitely check out that book, thank you for recommendation.
Quote by yungman No, I just read this!!! Slight change of COLLECTOR current due to early voltage effect, not the base current. I thought you ask whether you need to change the base voltage to keep collector current constant when you vary the collector resistor.
Slight change in 'forward gain' due to early voltage. This changes both the collector and the base current technically. If we assume the feedback mechanism hold Ie constant and the biasing network was correctly picked to hold Vb constant.
Ie is actually the controlled variable here. As the emitter and collector current are very close in a forward active high gain NPN usually we just consider them to be the same.
This link does a good job of running through the math.
http://www.stanford.edu/class/ee122/...Notes_Rev0.pdf
Start at section 6.
Google for "common emitter feedback" and you'll get a ton more links which explain it in various ways.
The above calculations assume an ideal NPN and therefore B is constant but it is pretty easy to see from their math what would happen if B was reduced due to early effect.
So I think the answer to the question you were really trying to ask, what breaks as I increase the pot's resistance, is B is reduced. Or, the NPN becomes a poorer amplifier even though it is still forward active.
Quote by es1 Slight change in 'forward gain' due to early voltage. This changes both the collector and the base current technically. The feedback mechanism in this circuit is designed to try to keep the emitter current constant. As the emitter and collector current are very close in a forward active high gain NPN usually we just consider them to be the same. This link does a good job of running through the math. http://www.allaboutcircuits.com/vol_3/chpt_4/10.html Google for "common emitter feedback" and you'll get a ton more links which explain it in various ways. The above calculations assume an ideal NPN and therefore B is constant but it is pretty easy to see from their math what would happen if B was reduced due to early effect. So I think the answer to the question you were really trying to ask, what breaks as I increase the pot's resistance, is B is reduced. Or, the NPN becomes a poorer amplifier even though it is still forward active.
So my hunch about Early effect was actually right? wow :D
Quote by Bassalisk So my hunch about Early effect was actually right? wow :D
Yup. I thought your original understanding of the NPN operation was right.
The feedback concept in this circuit is something else.
I edited my post a bit to try to keep the wording clearer. There are a number of moving pieces and as one adds details things get murkier so I wanted to make sure to state my assumptions. Hopefully the newer version, and the new link, is better.
Quote by es1 Yup. I thought your original understanding of the NPN operation was right. The feedback concept in this circuit is something else. I edited my post a bit to try to keep the wording clearer. There are a number of moving pieces and as one adds details things get murkier so I wanted to make sure to state my assumptions. Hopefully the newer version, and the new link, is better.
That little 3 legged animal can be as complicated as you want. The place where I find hard to explain is exactly what ES1 said, the collector current change due to the collector voltage as you change the collector resistor with the base voltage constant must mean there must be some change to the base current and the gain of the transistor. If you take into consideration of all these, it will never end. That is the reason I mentioned about the Malvino book. It present a very simplistic view of the transistor..........and surprisingly it is good enough to design very advanced circuits. You really chase to the bottom of this, you'll find it very long and unnecessary hard. From the question you ask, I think the Melvino book is perfect for you. Not only that, this book get the best introduction of op-amp I ever seen including Bode Plot. Baby steps, learn the basic of transistors and then go back and dig into it. It can fill up a whole thick just on this little animal. You are not going to get any simple answer on this. Read the book, ask questions here. If I have a chance, I'll try to look for the book on Amazon and see whether you can take a peek inside the section on DC biasing and AC equivalent of NPN.
Quote by yungman That little 3 legged animal can be as complicated as you want. The place where I find hard to explain is exactly what ES1 said, the collector current change due to the collector voltage as you change the collector resistor with the base voltage constant must mean there must be some change to the base current and the gain of the transistor. If you take into consideration of all these, it will never end. That is the reason I mentioned about the Malvino book. It present a very simplistic view of the transistor..........and surprisingly it is good enough to design very advanced circuits. You really chase to the bottom of this, you'll find it very long and unnecessary hard. From the question you ask, I think the Melvino book is perfect for you. Not only that, this book get the best introduction of op-amp I ever seen including Bode Plot. Baby steps, learn the basic of transistors and then go back and dig into it. It can fill up a whole thick just on this little animal. You are not going to get any simple answer on this. Read the book, ask questions here. If I have a chance, I'll try to look for the book on Amazon and see whether you can take a peek inside the section on DC biasing and AC equivalent of NPN.
Can you give me the title of the book?
I was trying to see whether Amazon will have "Look inside this book" option on this book, sadly they don't. Here is what I think is the book, mine is a very old edition 30 years back, it look nothing like this. I just remember the name of the author. Try this one, it is only about $4 used, so it would not be too much money if this is not the one. In fact I just bought one for myself. http://www.amazon.com/Electronic-Pri...9040280&sr=1-4 Look for the DC bias and AC equivalent section. It give you a lot of approximation to make it easy to learn. It does not even get into the early voltage which you don't really need. I am currently designing some electronics used in guitar and I am using the knowledge gained in that book. Just hope it's the right one. Quote by yungman I was trying to see whether Amazon will have "Look inside this book" option on this book, sadly they don't. Here is what I think is the book, mine is a very old edition 30 years back, it look nothing like this. I just remember the name of the author. Try this one, it is only about$4 used, so it would not be too much money if this is not the one. In fact I just bought one for myself. http://www.amazon.com/Electronic-Pri...9040280&sr=1-4 Look for the DC bias and AC equivalent section. It give you a lot of approximation to make it easy to learn. It does not even get into the early voltage which you don't really need. I am currently designing some electronics used in guitar and I am using the knowledge gained in that book. Just hope it's the right one.
I just LOVE good books. Might sound geeky but between google and a good book, I always go for a good book.
Thank you for the research, I will surely buy it.
Quote by Bassalisk I just LOVE good books. Might sound geeky but between google and a good book, I always go for a good book. Thank you for the research, I will surely buy it.
I hope you have not order that yet, I received the book, it is the exercise book for the text book, not the text book!!! No wonder it is so cheap!!!!
Recognitions: Gold Member Science Advisor i'd recommend the ancient Texas Instruments book "Transistor Circuit Design" a google showed it in a lot of used bookstores. While on the subject their wonderful "OpAmps for Everyone" is available as a download from TI's library search for slod006b.pdf and add it to your library...
No I didn't order from there, because I don't think Amazon can send to my country. I found it on ebay. http://www.ebay.co.uk/itm/Electronic...item2a14dafa8b
Quote by jim hardy i'd recommend the ancient Texas Instruments book "Transistor Circuit Design" a google showed it in a lot of used bookstores. While on the subject their wonderful "OpAmps for Everyone" is available as a download from TI's library search for slod006b.pdf and add it to your library...
Already did. Thank you. I am learning waaaay more than I need to pass my exam. This course I am taking is very narrow, although it should be since Im studying telecommunications. But I cannot just accept things like, negative feedback, differential amplifiers and so on. Need to have a nice explanation for it :)
Quote by Bassalisk No I didn't order from there, because I don't think Amazon can send to my country. I found it on ebay. http://www.ebay.co.uk/itm/Electronic...item2a14dafa8b
It is the correct author, make sure you get the text book, not the experiments book that I bought.
Btw. the book, Electronic Principles by Malvino, is just out of this world. I just wish I had it when I started learning transistors. Its making my life just 10 times more easy. Thank you very much.
I am glad you like it. Make sure you study the opamp and Bode Plot. It is very very good. It is so good that I even tried to buy one and get the wrong one. Don't think this is too simple to be useful, I designed heavy duty transistors circuits and integrated circuits for years, the stuff works. that little r'e and Vt that is 25ohm for 1mA and 25mV and room temperature is all you need to know and to scale the r'e with current.
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2013-05-24 16:19:10
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https://www.amplifiedparts.com/products/vacuum_tubes?sort=popular&filters=646a4b2546c1a646c2341a2417
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# Vacuum Tubes
The first electronic amplification of sound was done with Vacuum Tubes. We have pre-amp, power and rectifier vacuum tubes among other types in New Old Stock from the golden era of American & European manufacturing as well as current production tubes from today.
#### New Old Stock (NOS)
Our new-old-stock tubes were made by the major U.S. manufacturers, along with a small number of European manufacturers and are tested and guaranteed.
#### Vacuum Tubes
The first electronic amplification of sound was done with Vacuum Tubes. We have pre-amp, power and rectifier vacuum tubes among other types in New Old Stock from the golden era of American & European manufacturing as well as current production tubes from today.
Vacuum Tube - 6BE6 / EK90, Heptode
Miniature heptode primarily designed to perform the combined functions of the mixer and oscillator in superheterodyne circuits in both the standard broadcast and FM bands.
$6.90 Vacuum Tube - 12BE6 / HK90, Heptode Miniature pentagrid converter designed to perform simultaneously the combined functions of the mixer and oscillator in superheterodyne receivers. The tube is suitable for use in the standard broadcast and FM bands.$7.90
Vacuum Tube - 12AV6, Diode, Dual Triode
Combines a high mu triode and two independent diode units in the 7-pin miniature construction. It permits a single tube to function as detector, AVC rectifier, and audio amplifier.
$5.90 Vacuum Tube - 12SQ7, Diode, Dual, Triode Combines two diode units and a high-mu triode in a single envelope. Each section uses a common cathode. It is intended for service as a combined detector, AVC source, and high gain audio amplifier.$19.90
Vacuum Tube - 1R5 / DK91, Heptode
Miniature pentagrid-converter designed for use as a combined mixer and oscillator in superheterodyne circuits. Because of its small size and high operating efficiency, the 1R5 is especially adapted for compact, battery-operated equipment.
$5.90 Vacuum Tube - 12SA7, Heptode Pentagrid converter designed to minimize frequency drift. They are intended for service as combined oscillators and mixers in AC, storage battery, and AC/DC operated superheterodynes.$8.90
Vacuum Tube - 6SA7, Heptode
Metal pentagrid converter. It is intended to perform the combined functions of the mixer and oscillator in superheterodyne receivers, especially those of the all-wave type. The 6SA7 is constructed to provide excellent frequency stability.
$3.90 Vacuum Tube - 6AJ8 / ECH81, Triode, Heptode Triode-heptode for use in F.M., AM/FM, A.M, and television receivers.$8.90
Vacuum Tube - 6201 / 12AT7WA, Dual Triode, HI-MU
Miniature high-mu twin triode each section of which has an individual cathode connection. The tube is especially suited for use as a grounded-grid amplifier or as a frequency converter at frequencies below approximately 300 megacycles.
$10.95 Vacuum Tube - 19T8 / HABC80, Diode, Dual, Triode Miniature tube containing three high-perveance diodes and a high-mu triode in the same envelope. One of the diodes has a separate cathode connection. The tube is designed for use as a combined AM and FM detector and audio-frequency amplifier.$7.90
Vacuum Tube - 12DW7 / 7247, Dual Triode, GE
Dissimilar double triode in the 9-pin miniature construction. It is especially suitable for applications requiring a high gain voltage amplifier and a cathodyne type phase-inverter.
$24.95 Vacuum Tube - 7B8, Heptode Pentagrid converter designed to perform the combined functions of the oscillator and mixer in superheterodyne receivers$1.95
Save 50%
Originally: $3.90 Vacuum Tube - 5750 / 6BE6W, Heptode Miniature pentagrid converter designed for use as a combined mixer and oscillator in superheterodyne circuits.$4.90
Vacuum Tube - 12AT7 / ECC81, Triode, Dual, HI-MU
The 12AT7 is a miniature, high-mu, twin triode designed for use as a grounded-grid radio-frequency amplifier or as a combined oscillator and mixer at frequencies below approximately 300 megacycles.
$14.90 Vacuum Tube - 12SL7GT, Triode, Dual, HI-MU High-mu twin triode designed for use in resistance-coupled circuits as a voltage amplifier or phase inverter. Except for heater characteristics and ratings, the 12SL7GT is identical to the 6SL7GT.$6.90
Vacuum Tube - 5670 / 2C51W, Triode, Dual
Miniature medium-mu twin triode each section of which as a separate cathode connection. The tube is suited for use in a wide variety of general-purpose amplifier and mixer circuits as well as numerous multi-vibrator and oscillator applications.
$4.90 Vacuum Tube - 12SQ7GT, Diode, Dual, Triode Combines two diode units and a high-mu triode in a single envelope. Each section uses a common cathode. It is intended for service as a combined detector, AVC source, and high gain audio amplifier.$19.90
Vacuum Tube - 6189 / 12AU7WA, Triode, Dual, Medium MU
Miniature medium-mu twin triode suitable for a wide variety of general-purpose amplifier, oscillator, and multivibrator applications.
$14.95 Vacuum Tube - 5963 / 12AU7A, Dual Triode Miniature, medium-mu twin triode for use as a frequency divider in computer applications.$9.90
Vacuum Tube - 12BH7A, Triode, Dual, Medium MU
Miniature, medium-mu twin triode designed primarily for use as a vertical-deflection amplifier in television receivers. The two sections may be employed in parallel, or as a combined vertical-deflection amplifier and vertical oscillator.
$29.90 Vacuum Tube - 12DT8, Triode, Dual General-purpose high-mu twin triode of the 9-pin miniature type intended for use as an rf amplifier and as a combined oscillator-mixer in fm tuners. This tube is also useful in a wide variety of applications in radio and television receivers.$9.90
Vacuum Tube - 1LA6, Heptode
Low-voltage, low-current drain battery type pentagrid converter. It is designed for service as an oscillator and mixer in superheterodyne receivers which require only 90 volts of "B" battery and a single dry cell "A" battery.
$11.90 Vacuum Tube - 12SN7GT-A-B, Triode, Dual, Medium MU Medium-mu twin triode suitable for use in a wide variety of general purpose amplifier and phase-inverter applications. Except for heater characteristics and ratings, the 12SN7GA-B is identical to the 6SN7GTB$6.90
Vacuum Tube - 12AX7-A, Triode, Dual, High MU
Miniature high-mu twin triode each section of which has an individual cathode connection - especially suited for use in resistance-coupled voltage amplifiers, phase inverters, multivibrators, and industrial-control circuits.
\$59.95
Don't see what you're looking for? Send us your product suggestions!
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2020-08-07 21:34:44
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https://www.nature.com/articles/s41467-021-24648-x?error=cookies_not_supported&code=15c7981a-74fc-4673-b6cd-c95c5138cb77
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# Diffusion controls the ventilation of a Pacific Shadow Zone above abyssal overturning
## Abstract
Mid-depth North Pacific waters are rich in nutrients and respired carbon accumulated over centuries. The rates and pathways with which these waters exchange with the surface ocean are uncertain, with divergent paradigms of the Pacific overturning: one envisions bottom waters upwelling to 1.5 km depth; the other confines overturning beneath a mid-depth Pacific shadow zone (PSZ) shielded from mean advection. Here global inverse modelling reveals a PSZ where mean ages exceed 1400 years with overturning beneath. The PSZ is supplied primarily by Antarctic and North-Atlantic ventilated waters diffusing from below and from the south. Half of PSZ waters re-surface in the Southern Ocean, a quarter in the subarctic Pacific. The abyssal North Pacific, despite strong overturning, has mean re-surfacing times also exceeding 1400 years because of diffusion into the overlying PSZ. These results imply that diffusive transports – distinct from overturning transports – are a leading control on Pacific nutrient and carbon storage.
## Introduction
The world’s oldest seawater can be found in the mid-depth North Pacific where estimates of the ideal mean age exceed 1300 years1,2,3,4. The mid-depth North Pacific thus constitutes a vast reservoir of remineralized nutrients and respired carbon accumulated over a long time5,6. When the waters of this reservoir are returned to the surface, their high nutrient content supports biological production and their respired carbon can outgas to the atmosphere. While the ventilation of the deep Pacific is thus important for ocean biogeochemistry and climate, there is a great deal of uncertainty about the pathways and rates with which the deep Pacific and the surface ocean exchange water, with divergent schools of thought on the nature of the deep Pacific overturning circulation7,8.
The global pathways of newly formed deep water, and the mechanisms through which dense deep waters gain buoyancy to return to the surface, have long been of fundamental interest in oceanography. The observed radiocarbon age of water and simple mixing analyses of hemispherically distinct quasi-conservative properties have led to the concept of the great ocean conveyor9,10,11. This concept is epitomized by a schematic of the large-scale interbasin overturning circulation that has since been elaborated and refined based on absolute geostrophic transports7,12 and more comprehensive inverse modelling of observed tracer properties13,14,15. Schematics of the global overturning circulation have become an entrenched conceptual framework for discussing the ocean circulation and its climate-driven changes. However, these schematics are widely acknowledged to be an oversimplification of oceanic transport7,10,11,16, in large part due to their inability to adequately capture the role of eddy-diffusive mixing across different branches of the overturning circulation and between vigorously flowing and more stagnant regions such as the deep Pacific. An analysis of the local fraction of water in transit between specified surface regions in ocean models17,18,19 revealed that the pathways depicted in typical overturning schematics only capture the paths that are fast on the scale of the most probable interior residence time and that these advectively dominated fast paths carry typically much less than half the formation-to-reexposure flow rate. The bulk of the flow is carried by paths that explore much larger fractions of the ocean volume, and asymptotically slow paths are organized into the deep North Pacific by what has been dubbed the diffusive conveyor17.
There are currently two paradigms20 for the deep overturning of the Pacific (Fig. 1). The “standard conveyor” paradigm envisions Antarctic Bottom Water (AABW) upwelling and transforming to Pacific Deep Water (PDW) before flowing back south to the Southern Ocean. (The PDW core is considered7 to lie at a neutral density21 of γ = 27.8 kg m−3 or roughly 1.6 km depth north of 35S.) Although this paradigm does not commit to a definite latitudinal distribution of the upwelling AABW, its most recent schematic7 and its precursors10,11, as well as results from tracer inversions13,14,15, suggest a broad overturning cell that reaches above 2.5 km depth and into the Northern Hemisphere (Fig. 1a). (Geostrophic inverse models at 32S in the Indian Ocean similarly suggest an overturning circulation with a southward return above ~2000 m depth or higher22.) By contrast, it was recently argued8 that the area of seafloor intersected by a given density class is a key control on buoyancy-flux divergences and hence overturning. Because 85% of the seafloor lies at depths greater than 2.5 km, this argument implies a vertically compressed abyssal Pacific overturning with southward return flow below ~2.5 km depth (Fig. 1b). This theory hence predicts a weakly ventilated Pacific “shadow zone” that is isolated from the large-scale overturning by being sandwiched north of 32S between the abyssal overturning cell and the upper wind-driven thermocline circulation. We refer to this view of the Pacific overturning as the “shadowed conveyor” paradigm.
Here we investigate the overturning circulation and ventilation of the deep Pacific using a steady global Ocean Circulation Inverse Model (OCIM2,23) that assimilates the observed global distributions of potential temperature, salinity, CFC-11, CFC-12, natural radiocarbon (Δ14C) and δ3He, plus sea-surface height, and surface fresh-water and heat fluxes (see Methods). Due to the inclusion of multiple tracers, as well as dynamical constraints2, the OCIM is much better constrained than geostrophic box inverse models13,14,15,24 constructed from hydrographic sections. The OCIM’s high fidelity to the observed tracer distributions and its matrix formulation of the advective-diffusive flux-divergence operator, which allows efficient implementation of Green-function-based diagnostics (see Methods), makes it one of the best available tools for investigating oceanic transport.
For this study, we have doubled the OCIM’s vertical resolution to 48 layers to better resolve deep flows, and we prescribe a spatially varying diapycnal diffusivity κ based on tidal mixing25 while optimizing the local isopycnal eddy-diffusivity κ together with the resolved velocity field. κ has a large dynamic range with local values below the mixed layer from 1.4 × 10−7 to 7.7 × 10−2 m2 s−1, an average above 3000 m depth of 0.31 × 10−4 m2 s−1, and an average below 3000 m of 1.6 × 10−4 m2 s−1. κ ranges from 134 ± 2 to 4108 ± 28 m2 s−1 with a global mean of 647 ± 16 m2 s−1. κ exceeds 2000 m2 s−1 in strongly baroclinic regions broadly consistent with observation-based estimates26,27,28 and high-resolution modelling29 (Supplementary Note and Supplementary Fig. 1). The tidal mixing parameterization of κ includes both bottom-intensified local mixing and stratification-dependent remote mixing25; the latter has recently been shown to be important for modelling a realistic ocean radiocarbon distribution30 and by implication deep-ocean ventilation timescales. Bottom-intensified mixing is essential for the OCIM to capture a well-defined shadow zone with vertically compressed abyssal overturning beneath, consistent with the theory8 that diapycnal mass-flux divergences are driven by exposure to the seafloor.
To assess the sensitivity of our results to the values of κ, we consider three ocean states: a base state optimized using κ as recently mapped and successfully compared to available turbulence observations25, and two optimized perturbed states for which this κ is either uniformly scaled up or down by a factor of 2. (This four-fold range of κ brackets the total power input to small-scale turbulence in the ocean interior31 from 0.5 to 2.0 TW, making a significantly larger range for κ in the global mean unlikely.) The uncertainty of any quantity X reported here is the half-range spread $$[\max (X)-\min (X)]/2$$ for the $$\min$$ and $$\max$$ of X across the three states. Note that because the OCIM is optimized for each state to fit the observational constraints as closely as possible, the sensitivities quantified here are smaller than the sensitivities to the same changes in κ expected for a forward ocean model. Based on the OCIM circulation, we define shadow and abyssal zones of the North Pacific and systematically quantify the advective-diffusive transport that ventilates these zones and re-exposes their water back to the atmosphere.
## Results
### Overturning, mean ventilation times, shadow and abyssal zones
The OCIM-optimized Pacific meridional overturning circulation (PMOC, Fig. 2a, computed as the meridional flow at neutral densities greater than a specified value and mapped back to depth-latitude space32) has a deep cell with northward streamflow of AABW well into the Northern Hemisphere; abyssal inflows and outflows across the equator are roughly 8 Sv. The maximum deep overturning of 8.6 ± 0.3 Sv (1 Sv = 106 m3 s−1) at ~6S and neutral density γ = 28.12 kg m3 is consistent with the estimate of 10.6 ± 1.7 Sv for flow through the Samoan and adjacent passages based on moorings and hydrography33,34,35,36, but significantly smaller than the ~14 Sv of AABW inflow inferred from absolute geostrophic velocities7,37. Contrary to the standard conveyor paradigm, the deep overturning cell is vertically compressed and does not feature southward flow centred around γ = 27.8 kg m−3. In broad agreement with theoretical predictions based on density transformation driven by exposure to the seafloor8, the change in direction from abyssal northward flow to overlying southward flow lies around γ = 28.1 kg m−3, and the southward mean flow north of ~30S is approximately confined to depths below 2.5 km. Note that both paradigms allow a few Sv of upwelling into the thermocline circulation. Here, the vertical streamflow across 2.5 km depth is generally weak but by ~30S approaches roughly ~4 Sv, reaching as high as γ = 27.4 kg m−3 and onward into the thermocline. The sensitivity of the PMOC to a factor-of-2 change in κ leads to a PMOC half-range (Fig. 2b) that is less than 1 Sv below 1 km depth, but reaches ~3 Sv in the vigorous southern thermocline circulation.
The North Pacific between roughly 1.5 and 3 km depth is largely shielded from the PMOC and can thus be considered a shadow zone8 of the large-scale streamflow, consistent with the shadowed conveyor paradigm. This shadow zone is expected to be weakly ventilated as can be quantified by the ideal mean age, Γ, the mean time since ventilation anywhere at the surface: The Pacific zonal mean of Γ has its maximum in the shadow zone and its 1400-year contour roughly circumscribes it (Fig. 2c). This region is also where the ocean’s oldest radiocarbon ages ΓC are observed5,38,39; ΓC closely approximates Γ in the deep ocean when corrected for the distribution of ΓC at the surface40. Beneath the shadow zone, Γ decreases by several hundred years with depth and latitude, consistent with better ventilation through coherent AABW access from the south. Changing the magnitude of κ by a factor of 2, and re-optimizing, changes Γ by less than 1% (Fig. 2d), consistent with the high-fidelity fits to observed Δ14C (see Methods).
While Γ provides a measure of the degree of isolation from the overturning, the mean time to next ventilation anywhere at the surface (mean re-exposure time, Γ, Fig. 2e) has a qualitatively different pattern in the deep Pacific highlighting the asymmetric nature of advective-diffusive transport. Water in the abyssal North Pacific is shielded the longest from next ventilation, with a zonal-mean Γ in excess of 1400 years. This shows that the deep overturning circulation is not efficient in returning AABW back to the surface. As newly ventilated AABW is advected into the abyssal North Pacific, a significant portion (quantified below) diffuses upward out of the direct influence of the overturning, thus imparting these waters with the ocean’s longest mean re-exposure times. The local mean residence time of water in the ocean interior (i.e., the mean time between successive ventilations) is given by Γ + Γ (not shown), which has only weak vertical gradients in the North Pacific below roughly 1.5 km depth. The sensitivity of Γ to changes in κ (Fig. 2f) is roughly 4 times larger than for Γ, underlining that tidal mixing is a key control on buoyancy gain and return to the surface.
For a quantitative analysis of the ventilation and re-exposure rates and pathways of the deep North Pacific, we define the Pacific Shadow Zone (PSZ) as the region of the North Pacific bounded horizontally by 1.5 and 3 km depth and vertically by the equator, and we define the Pacific Abyssal Zone (PAZ) as the region immediately beneath the PSZ (Fig. 2). We do not extend the PSZ into the Southern Hemisphere to minimize advective transport into and out of the PSZ and to better align its location with tracer properties such as the ideal mean age Γ.
### Surface-to-interior and interior-to-surface fluxes and mean transit times
Maps of the surface ventilation flux Φ of water destined for a given interior zone (Fig. 3a, c) and of the surface re-exposure flux Φ of water from a given interior zone (Fig. 3b, d) reveal that to first order the conduits into and out of the deep North Pacific are very similar for the shadow and abyssal zones. Before examining these fluxes further, it is important to distinguish them from the net volume fluxes across the base of the mixed layer. Here we calculate the flux of water in transit since last contact with a specified origin region (a surface grid box for Φ and an interior zone for Φ) that is bound to make next contact with a specified destination region. To avoid overcounting, we exclude fluid elements that make repeat contact with the origin region or make contact with the sea surface along the way (see Methods). Importantly, these fluxes are thus one-way (or gross) fluxes41,42 that are more useful ventilation metrics than the net volume fluxes because the one-way fluxes govern surface–interior tracer exchange which can be non-zero even for zero net flux43.
The pattern of the ventilation flux Φ is dominated by the high-latitude deep-water formation regions: The subpolar North Atlantic and Nordic Seas, and the Weddell and other Antarctic marginal seas. The pattern of the re-exposure flux Φ is largest in the Southern Ocean, in regions of tropical upwelling, and in the subarctic Pacific (re-exposure in the subpolar North Atlantic is 3–4 orders smaller; the fluxes in Fig. 3a–d are plotted with a logarithmic color scale). The globally integrated surface-to-interior flow rate, balanced exactly for our steady-state circulation by the corresponding interior-to-surface flow rate, is 11.4 ± 0.3 Sv for the PSZ and 9.1 ± 0.1 Sv for the PAZ.
To reveal the differences between the PAZ and PSZ surface fluxes, Fig. 3e shows the PAZ–PSZ difference of the normalized ventilation fluxes, $${{\Delta }}{\widehat{{{\Phi }}}}^{\downarrow }$$, and Fig. 3f shows the differences of the normalized re-exposure fluxes, $${{\Delta }}{\widehat{{{\Phi }}}}^{\uparrow }$$. Normalization of the fluxes (by dividing by their global surface integral) is necessary to eliminate the effects of the different interface areas of the interior zones; for example, if all else were equal, we would expect larger total flow rates for the PSZ merely because it can be accessed from below, while the bottom of the PAZ is blocked by the seafloor. The normalized differences show that on a per-Sverdrup basis, the deeper, denser PAZ is preferentially (i.e., relative to the PSZ) ventilated in the deep-water formation regions, while the less dense PSZ is preferentially ventilated where subpolar mode and intermediate waters form. On a per-Sverdrup basis, the PAZ is preferentially re-exposed to the atmosphere in the Southern Ocean south of roughly 45S, while the PSZ is preferentially re-exposed via upwelling in the tropical Indo-Pacific and in the subarctic Pacific (where there is a shallow overturning circulation). While revealing, the differences between the normalized flux patterns are small, with peak differences in the zonally integrated patterns on the order of 1% of the total global flux per degree latitude. This underlines that the geographic locations of the conduits into and out of the ocean interior are to first order determined by upper-ocean dynamics; deep-ocean destination or origin is of secondary importance.
The mean surface-to-interior transit times Γ and mean interior-to-surface transit times Γ, averaged over a given interior zone, are mapped out in Fig. 3g–j. The mean transit times Γ from the North Atlantic surface into the PSZ are about 1700 years, roughly 300 years older than the mean transit time from the North Atlantic into the PAZ, which underscores the fact that (as quantified below) roughly half the water last ventilated in the North Atlantic that enters the PSZ does so by diffusing up into the PSZ while traversing the PAZ. By the same token, the mean transit time from the Antarctic margin, where AABW forms, to the PAZ is around 1100 years, but to the PSZ it is 1400–1500 years. Mode/intermediate waters from the subpolar Southern Ocean reach the mid-depth PSZ on average in 1000–1200 years, which is roughly 200–400 years more quickly than their mean transit into the deeper PAZ (Fig. 3g, i). There is less geographic variation in the mean interior-to-surface transit times Γ. Although only about 1% of the waters of either zone is re-exposed in the North Atlantic, the mean re-exposure times to the North Atlantic, remote from the North Pacific, are the longest for the PSZ (roughly 1300 years, Fig. 3h) and comparable to the transit times of equatorial re-exposure for the PAZ (roughly 1500 years, Fig. 3j). Re-exposure of PSZ waters in the subarctic Pacific, tropical oceans, and Southern Ocean are around 1000–1200 years, while the corresponding re-exposure times for the PAZ are about 400 years longer in the tropical and North Pacific and about 200 years longer in the Southern Ocean, again consistent with re-exposure of dense PAZ waters involving additional slow upward diffusion relative to the PSZ.
### Origin/destination partitioned transport rates and volumes
Despite small streamflow through the PSZ, there can be substantial eddy-diffusive transport into and out of the PSZ if there are gradients in the transported property across its boundaries. The property relevant for our analysis is the concentration of the subset of fluid elements that was labelled in its origin region and whose origin label is removed on contact with the destination region (and on contact with the surface and on repeat contact with the origin region), as we track water from the surface to its first contact with an interior zone or from an interior zone back to the surface (see Methods).
The streamflow across the faces of the PSZ is weak (cf. Fig. 2) with rates of around 1 Sv, which is of the same order of magnitude as their half-range spread (Fig. 4b, c). By contrast, the surface-to-PSZ transport rate is 11.4 ± 0.3 Sv, which occurs primarily through the vertical (5.23 ± 0.06 Sv) and bottom (4.2 ± 0.3 Sv) faces. The balancing PSZ-to-surface transport is also largest through the vertical face (7.0 ± 0.3 Sv), with additional transport through the top face (3.5 ± 0.2 Sv). The fact that there is substantial transport to and from the PSZ in the absence of strong coherent overturning underscores the importance of isopycnal eddy diffusion through its equatorial side and diapycnal diffusion through its top and bottom faces.
As seen in Fig. 2, the streamflow across the equatorial boundary of the PAZ is organized by large-scale coherent overturning. The volume flow rate through the equatorial PAZ boundary below the maximum of the overturning stream function at neutral density γ = 28.12 kg m−3 represents an inflow of 7.8 ± 0.2 Sv (Fig. 4b), while above γ = 28.12 kg m−3 there is an outflow of 7.0 ± 0.8 Sv (Fig. 4c). The horizontal transport rates through the vertical face of the PAZ, both from and to the surface, are of a similar magnitude as these deep overturning rates. This and the fact that transport to the PAZ from the surface occurs mostly through its lower half (roughly below γ = 28.1 kg m−3), while transport from the PAZ to the surface occurs mostly through the upper half (quantified below), underscore the importance of horizontal advection for the PAZ. The PAZ-to-surface transport rate of 4.5 ± 0.4 Sv through the PAZ top face is about three times as large as the corresponding surface-to-PAZ transport. The fact that PAZ-to-surface transport through the PAZ top face must pass through the largely advectively decoupled PSZ indicates that this transport is controlled by diapycnal diffusion.
In Fig. 4, we have partitioned both the transport rates as well as the water volume of the interior zones according to where water was last ventilated at the surface (for surface-to-interior transport, Fig. 4b) or according to where it will next be re-exposed to the atmosphere (for interior-to-surface transport, Fig. 4c). To quantify the spatial structure of the transport pathways, we computed the path density which is the local fraction of water in transit since last contact with a specified origin region to next contact with a specified destination region18 (see Methods). The zonal-mean path densities are plotted in Fig. 5. Surface origin/destination is defined in terms of the 5 broad regions of Fig. 4a. The precise boundaries of the regions do not matter as the ventilation and re-exposure patterns are highly localized within these regions (Fig. 3a–d is plotted on a logarithmic scale; e.g., within the northern Pacific region ventilation occurs predominantly at mid-latitudes and in the western marginal seas while re-exposure occurs predominantly in the subarctic Pacific.) The volumetric partitioning (pie charts of Fig. 4) is qualitatively similar to the flux partitioning (colored arrows of Fig. 4) because the mean transport timescales vary by at most 50% from region to region (Fig. 3g–j). We refer to water last ventilated in the North Atlantic as North Atlantic Deep Water (NADW) and water last ventilated along the Antarctic margin as AABW. Note that this definition of water masses differs from that provided by an optimal admixture of pre-defined quasi-conservative source properties or “end members”44,45.
NADW and AABW are the dominant volumetric contributors to the ventilation of both the PAZ and PSZ (each contributing roughly 35–40% of the water volume of each zone), with the bulk of the remaining 20–30% coming from the subpolar Southern Ocean (mode/intermediate waters) (pie charts of Fig. 4b). NADW is about equally important for both the PAZ and PSZ, while AABW contributes relatively more to the PAZ, and mode/intermediate waters contribute relatively more to the PSZ, consistent with Fig. 3e, f. The low&mid-latitude and northern Pacific regions each contribute 5% to the PSZ volume and roughly 3% to the PAZ volume. This is consistent with some mode waters formed in the poleward flanks of the low&mid-latitude region mixing to depth (cf., Fig. 3a, c), observed deep and intermediate-water formation in the marginal seas of the western North Pacific46,47, and downward (in addition to upward; see below) diffusive transport in the subarctic Pacific.
The dominant surface-to-PAZ transport (Fig. 4b) through the vertical PAZ face at the equator is primarily due to AABW and NADW, both of which are transported to the PAZ mostly at densities greater than γ = 28.1 kg m−3 (Fig. 5f, j). The surface-to-PSZ transport (Fig. 4b) through the PSZ base is similarly dominated by AABW and NADW because all water entering the PSZ from below must pass through the PAZ (Fig. 5a, e). The surface-to-PSZ transports through its side and bottom faces have similar AABW and NADW contributions, but the transport through the side also contains a mode/intermediate component of comparable magnitude (Fig. 4b). Thus, the greater importance of mode/intermediate waters for ventilating the PSZ relative to the PAZ is due to quasi-horizontal isopycnal transport. Mode/intermediate waters enter the PSZ primarily through its top corner, with a small amount entrained into AABW entering from below (Fig. 5b). Most water in transit to the interior zones from the subpolar Southern Ocean can be found in the γ = 27.6–27.8 kg m−3 neutral-density range or for γ > 28.1 kg m−3 (Fig. 5b, g).
Volumetrically, the dominant destination regions for re-exposure are the Southern Ocean, the tropical oceans, and the subarctic Pacific (pie charts of Fig. 4c, maps of Fig. 3b, d). As a re-exposure destination, the northern Atlantic makes a negligible (~1%) contribution to either interior zone. For both the PSZ and PAZ, the Southern Ocean is the destination for more than half the water (52% and 62%, larger for the denser PAZ). The remainder is roughly equally split between water destined for re-exposure in low latitudes and in the subarctic Pacific.
For re-exposing PAZ water back to the surface (Fig. 4c), horizontal transport out of the side with the overturning and vertical transport out of the top are roughly equally important. The transport from the vertical PAZ face at the equator is driven by advection with the upper, lower-density branch of the overturning (28.05 γ 28.12 kg m−3). As PAZ water is transported isopycnally, it establishes a core between roughly γ = 27.9 and 28.0 kg m−3 and diffuses diapycnally into both lighter and denser layers that outcrop in the subpolar Southern Ocean and in the Antarctic margin, respectively (Fig. 5p, q). Transport rates from the vertical PAZ face to the Southern Ocean are roughly twice as large as transport rates from the top PAZ face to the Southern Ocean, with about half of the transport from the top destined for tropical and subarctic Pacific re-exposure (Fig. 4c). The required dianeutral diffusion on the way to non-Southern Ocean re-exposure (Fig. 5r, s) is manifest by several-hundred-years older mean re-exposure times (Fig. 3j).
The re-exposure of PSZ water (Fig. 4c) takes place primarily through its side face via isopycnal transport to the Southern Ocean with a core between roughly γ = 27.8 and 28.0 kg m−3 (Fig. 5k, l). Isopycnally transported water from the PSZ top and upper corner diffuses and upwells to lighter density to access the thermocline circulation (Fig. 5m, n) which delivers this water to equatorial (~2.3 Sv) and subarctic Pacific upwelling (~2.5 Sv). Mean re-exposure times Γ for these waters are around 1100 years, roughly 500 years less than for PAZ-water that first needs to diffuse across the PSZ to get to the same surface destinations (Fig. 3h, j).
## Discussion
Our analysis allows us to assess the degree to which the standard conveyor7 and the shadowed conveyor8,48 paradigms capture key aspects of the Pacific deep circulation and transport. The abyssal overturning of the OCIM is vertically compressed below roughly 3 km depth with an overlying shadow zone in good agreement with the shadowed conveyor paradigm8. The OCIM data-assimilated PMOC does not have a coherent, advectively dominated 10–15 Sv of AABW upwelling to around 1.5 km depth as inferred by geostrophic inverse models13,14 and suggested by typical conveyor schematics7,11,13. Our results therefore inspire a revamped schematic of the ventilation of the deep North Pacific which emphasizes the presence of a diffusively ventilated shadow zone above vertically compressed overturning that ventilates abyssal waters (Fig. 6).
The 11 Sv ventilating the PSZ occur mostly through quasi-horizontal isopycnal diffusion across the equator and via diapynal diffusion from below, while transport to surface re-exposure occurs mostly isopycnally across the equator and diapycnally through the top face of the PSZ (Fig. 6). The upwelling branch of the standard conveyor paradigm must therefore be interpreted broadly as representing the Lagrangian pathways of diapycnally diffusing, buoyancy gaining fluid elements rather than a branch of the PMOC. However, even broadened to a Lagrangian interpretation, the standard conveyor paradigm does not capture the existence of a shadow zone and the importance of isopycnal diffusive transport into and out of it. Precisely where water in the deep Pacific was last ventilated and where it will next be re-exposed to the atmosphere is beyond the scope of either paradigm.
Whereas the standard conveyor paradigm for the Pacific emphasizes the transformation of AABW to PDW, our analysis additionally highlights the importance of NADW in ventilating the deep Pacific (Fig. 6). The PSZ is fed diapycnally from below and isopycnally from the side by AABW and NADW in roughly equal measure with additional isopycnal input of mode/intermediate waters. Overall, our results underline that isopycnal diffusion is a critically important control on ventilation52,53.
The global surface patterns of ventilation and re-exposure are very similar for the PSZ and PAZ. The main conduits into the ocean interior are the high-latitude deep-water formation regions, while the main conduits out of the interior are the subpolar oceans and tropical upwelling, regardless of destination or origin in the deep ocean. The differences between the PSZ and PAZ manifest as subtle shifts in the relative importance of key surface regions that are isopycnally connected to these interior zones: mode/intermediate water formation is more important for PSZ ventilation, while Antarctic marginal seas are more important for the re-exposure of the denser PAZ.
Water in the PSZ has the ocean’s oldest ideal mean age (>1400 years) and is thus effectively shielded from ventilation. However, the water in the PSZ is not isolated the longest from re-exposure to the atmosphere. The longest re-exposure times (>1400 years) lie in the PAZ beneath the PSZ because much of the re-exposure of PAZ water occurs though diapycnal diffusion into the overlying shadow zone (Fig. 6) where the slow paths of the diffusive conveyor bring these waters to the surface. This underscores that access to a strong overturning circulation does not guarantee rapid transport.
By providing a more comprehensive, quantitative description of how deep North Pacific waters are ventilated and ultimately re-exposed to the surface, our analysis reconciles the two paradigms of the overturning circulation as capturing distinct aspects of the deep Pacific circulation. While the shadowed conveyor gives a better description of the vertically compressed PMOC, the standard paradigm, broadly interpreted, captures the slow diffusively dominated paths through the shadow zone. Our revamped ventilation schematic explicitly separates these two pathways while also highlighting the connectivity of the abyssal and shadow zones through diapycnal diffusion as well as the substantial diffusion-mediated transport of deep North Pacific waters to the low-latitude and subarctic Pacific surface (Fig. 6).
## Methods
### OCIM
The ocean circulation inverse model (OCIM) is a three-dimensional dynamical ocean model that assimilates ocean tracer data to estimate the climatological mean state of the ocean circulation2,4,23. The OCIM solves linearized steady-state momentum equations with neglected nonlinear terms and any discretization errors assigned to an adjustable forcing field. The equations are discretized on an Arakawa B grid55 with horizontal levels, and the observed density distribution is prescribed. Here, we update the most recent 24-layer version, OCIM24, to an improved 48-layer version OCIM2-48L. OCIM2-48L assimilates six different circulation tracers: potential temperature (Θ), salinity (S), CFC-11, CFC-12, natural radiocarbon (Δ14C), and natural δ3He. Annual mean objectively analyzed observations of Θ and S are taken from the 2013 World Ocean Atlas56,57. CFC-11 and CFC-12 measurements were taken from version 2 of the Global Ocean Data Analysis Project (GLODAPv258). For Δ14C, we use the same compilation of observations used for OCIM2, which includes data from GLODAPv2, a compilation of Δ14C measurements from surface corals59, historical Δ14C measurements60, and a collection of pre-bomb surface ocean Δ14C measurements from the 14CHRONO database (available at http://calib.org/marine/). OCIM2-48L uses the same set of δ3He observations as OCIM2, which includes δ3He observations from GLODAPv2 and from a transect in the Eastern Tropical Pacific61. The Δ14C and δ3He observations were processed using exactly the same procedure as for OCIM2, which includes screening for and removal of observations that are potentially contaminated by bomb radiocarbon and tritiogenic 3He. OCIM2-48L also assimilates the climatological average air-sea heat and freshwater fluxes from the NCEP reanalysis for the period 1980–200962 as well as the mean dynamical sea surface topography from the AVISO data product for the period 1993–1999 (release MDT-CNES_CLS09).
These observations are assimilated into OCIM2-48L by adjusting model parameters to minimize a quadratic cost function that measures the misfit between model and observations2,4,23. For the CFCs, the time-dependent surface boundary conditions are propagated to the time and location of the GLODAPv2 measurements. An adjoint approach63,64 is used to determine the optimal model parameters that minimize the misfit cost function. As for OCIM2, these parameters include (i) a set of parameters to adjust the local geostrophic momentum balance to mimic unresolved physics and to account for model discretization errors, (ii) a set of parameters to adjust the restoring temperature and salinity used for simulating air-sea heat and freshwater fluxes at the sea surface, (iii) a set of parameters to adjust the local mantle 3He injection rate along mid-ocean ridges, and (iv) a single parameter to control the global relationship between gas-transfer velocity and wind speed, using a quadratic wind-speed dependence65. OCIM2-48L uses an additional set of adjustable parameters that controls the local value of the isopycnal diffusivity. Like previous OCIM versions, the parameters and circulation are time-invariant and thus neglect temporal (e.g., seasonal or interannual) variability. The model thereby yields a climatological mean-state estimate of the combined advective-diffusive tracer transport.
OCIM2-48L includes several updates and improvements to better represent the deep Pacific ventilation. First, the vertical resolution has been increased from 24 to 48 levels. The thickness of the layers ranges from about 10 m near the sea surface to 300 m in the abyssal ocean. This is important for better resolving the vertically compressed overturning of the deep Pacific. The horizontal resolution remains at 2 degrees, which is sufficient for resolving the large-scale circulation of the Pacific. Second, the vertical diffusivity κ in OCIM2-48L is parameterized using a recently developed global model of tidal energy dissipation25 due to breaking internal waves generated by tides flowing over uneven topography. This formulation of κ replaces the less realistic constant or depth-enhanced background diffusivity used in previous OCIM versions. Like previous versions of the OCIM, OCIM2-48L has enhanced vertical diffusivities in the surface mixed layer that are parameterized using the KPP scheme66. However, OCIM2-48L prescribes a climatological annual mean mixed-layer depth67 rather than the monthly maximum mixed-layer depth used in previous versions4,23. Finally, to account for buoyancy gain by direct geothermal heating, we have included a recent estimate of the geothermal seafloor heat-flux distribution68.
The high fidelity of OCIM2-48L-assimilated tracer distributions to the observations is quantified in Table 1 in terms of the root-mean-square error (RMSE) and Pearson’s correlation coefficient r, for both the global and Pacific-basin fields. The improved parameterization of diffusivity and higher vertical resolution result in RMS errors that are 15–50% smaller than those for OCIM24. For all tracers, the fit in the Pacific is slightly better than the global fit, making OCIM2-48L well-suited for quantifying deep Pacific transport.
### Origin-to-destination water-mass fractions, path densites, flow rates, and transit times
We track water from origin to destination by labeling the water with a passive tracer. The OCIM’s steady discretized advection-diffusion flux-divergence operator is organized into a matrix T, and all gridded scalar fields are organized into corresponding column vectors, so that the generic tracer equation for concentration χ is ∂tχ + Tχ = S, where S are the discretized source/sink terms. Because OCIM flow is steady, T is time-independent.
For the calculations here, we define 3 regions in terms of their discretized mask vector: the global surface layer Ωs, a subregion of the surface Ωa, and an interior region Ωb (the PAZ or PSZ). (The entries of these masks are zero or unity depending if the corresponding grid point lies in the region or not.) We then calculate the local fraction Gadt of water that had last contact with Ωa during time interval (−dt, 0] without having had contact with Ωs and Ωb for t > 0. Disallowing repeat contact with Ωa ensures that water is labelled according to last Ωa contact, which avoids overcounting and makes it possible to partition according to transit time. Disallowing contact with Ωs ensures that integrals over the global sea surface give the net contribution from the sea surface (see also discussion of the flow rates below).
To enforce the condition of no contact with Ωs and Ωb, we remove Ωa-labelled water as soon as it makes contact with these regions, i.e., we impose the boundary condition that Ga = 0 in Ωs and Ωb for t > 0. The most convenient way to enforce these boundary conditions numerically is by relaxing Ga to zero with a fast timescale τ for grid points inside Ωs and Ωb. (For τ small compared to the time for transport across a typical grid box there is no sensitivity to the precise value of τ; we use τ = 10 s.) Thus, Ga obeys
$${\partial }_{t}{G}_{a}+{\bf{T}}{G}_{a}={{\bf{L}}}_{s}({{{\Omega }}}_{a}\delta (t)-{G}_{a})+{{\bf{L}}}_{b}(0-{G}_{a}) ,$$
(1)
where δ(t) is the Dirac delta function specifying the labelling-rate distribution on Ωa, and we have defined the diagonal matrices Ls ≡ diags/τ) and Lb ≡ diagb/τ). (Note that LsΩa = Ωa/τ as Ωa is a subset of Ωs.) Similarly, the fraction that had last contact with Ωb during (−dt, 0], and no contact with Ωs and Ωb since then, is given by
$${\partial }_{t}{G}_{b}+{\bf{T}}{G}_{b}={{\bf{L}}}_{b}({{{\Omega }}}_{b}\delta (t)-{G}_{b})+{{\bf{L}}}_{s}(0-{G}_{b}) .$$
(2)
(Note that LbΩb = Ωb/τ.)
The local steady-state fractions of water that had contact with Ωa or with Ωb at some point in the past (without further contact with Ωs or Ωb) are given by $${f}_{a}^{\downarrow }=\mathop{\int}\nolimits_{0}^{\infty }{G}_{a}\ dt$$ and $${f}_{b}^{\downarrow }=\mathop{\int}\nolimits_{0}^{\infty }{G}_{b}\ dt$$. Time integrating (1) and (2) and defining Tsb ≡ T + Ls + Lb, gives
$${f}_{a}^{\downarrow }={{\bf{T}}}_{sb}^{-1}{{{\Omega }}}_{a}/\tau \qquad {\rm{and}}\qquad {f}_{b}^{\downarrow }={{\bf{T}}}_{sb}^{-1}{{{\Omega }}}_{b}/\tau .$$
(3)
The corresponding fractions $${f}_{a}^{\uparrow }$$ and $${f}_{b}^{\uparrow }$$ that will make next contact with Ωa or Ωb at some time in the future are obtained in the same manner but for the time-reversed adjoint flow69. The time-reversed adjoint of Tsb is given by $${\widetilde{{\bf{T}}}}_{sb}\equiv {{\bf{W}}}^{-1}{{\bf{T}}}_{sb}^{T}{\bf{W}}$$, where the T superscript denotes matrix transpose and W = diag(w), with w being the column vector of grid-box volumes. Thus, $${f}_{a}^{\uparrow }$$ and $${f}_{b}^{\uparrow }$$ are simply obtained by replacing Tsb with $${\widetilde{{\bf{T}}}}_{sb}$$ in (3). The Ωa → Ωb path density ηab (integrated over all transit times) and the Ωb → Ωa path density ηba are given by
$${\eta }_{a\to b}={f}_{a}^{\downarrow }\circ {f}_{b}^{\uparrow }\qquad {\rm{and}}\qquad {\eta }_{b\to a}={f}_{b}^{\downarrow }\circ {f}_{a}^{\uparrow } ,$$
(4)
where denotes the element-wise product. The path density (4) is the local fraction of water in Ωa → Ωb transit; previous definitions of the path density17,18 considered only surface-to-surface transport for which ηab was additionally normalized by the ocean volume.
We calculate the Ωa → Ωb volume flow rate Φab by calculating the rate with which the fast relaxation removes Ωa-labelled water over Ωb. To get the total flow rate, we volume integrate over Ωb, and to get the flow rate into a particular face of Ωb, we integrate over the grid layer of the face only. (For short τ a single layer gives accurate results.) Thus, the total Ωa → Ωb volume flow rate can be written as
$${{{\Phi }}}_{a\to b}=(1/{\tau }^{2}){{{\Omega }}}_{b}^{T}{\bf{W}}\ {{\bf{T}}}_{sb}^{-1}{{{\Omega }}}_{a}=(1/{\tau }^{2}){{{\Omega }}}_{a}^{T}{\bf{W}}\ {\widetilde{{\bf{T}}}}_{sb}^{-1}{{{\Omega }}}_{b} .$$
(5)
The second expression of (5) is written in terms of the time reversed adjoint, which is particularly useful if the volume flow rate is desired at every grid point of Ωs, in which case the adjoint expression can be used to find the surface map of the flux in a single step by replacing Ωa with diags), each column of which is the Ωa mask for a single surface grid box. Note that the Φab flow rates are robust transport metrics that integrate the effect of advection and diffusion over all possible paths from Ωa to Ωb because Φab is the flux into Ωb of water labelled at Ωa. To calculate Φba volume flow rate, we simply interchange a and b in (5). The surface flux Φ of the main text is computed at a given surface point by choosing Ωa as the corresponding surface grid box, Ωb as the interior destination region of interest (PSZ or PAZ), and dividing by the horizontal area of Ωa to obtain the volume flux, i.e., the volume flow rate per unit area. Φ is computed similarly, but with origin and destination interchanged.
Excluding repeat contact with the origin region eliminates the flux in the opposite direction, rendering Φab a one-way or gross flow rate41,42,43, with the usual net volume flow rate being the residual of the gross rates for opposite directions. If the origin region is part of the surface, excluding contact with the surface elsewhere ensures that summing over surface-origin regions tiling the global sea surface gives the total one-way flow rate from the surface. (Similarly, for the case where the destination region is part of the surface, excluding surface contact elsewhere ensures partitioning the total one-way flow rate into the surface layer without overcounting.) In this study, Ωa and Ωb neither overlap nor abut, ensuring that the corresponding flow rates are non-singular43,69.
To calculate the surface maps of Ωb-volume-averaged mean transit time, we consider Ga, which obeys the same equation as Ga, but without relaxation to zero on Ωb. The local fraction in the ocean interior that had last surface contact in Ωa is then given by $${f}^{\downarrow }={{\bf{T}}}_{s}^{-1}{{{\Omega }}}_{a}/\tau$$, where Ts ≡ T + Ls, and the normalized Ωb-volume-averaged transit-time distribution is given by $${\mathcal{G}}=({{{\Omega }}}_{b}^{T}{\bf{W}}\ {G}^{a})/({{{\Omega }}}_{b}^{T}{\bf{W}}\ {f}^{\downarrow })$$. The corresponding mean age is given by69
$${{{\Gamma }}}^{\downarrow }=\mathop{\int}\nolimits_{0}^{\infty }{\mathcal{G}}tdt=({{{\Omega }}}_{b}^{T}{\bf{W}}\ {{\bf{T}}}_{s}^{-2}{{{\Omega }}}_{a})/({{{\Omega }}}_{b}^{T}{\bf{W}}\ {{\bf{T}}}_{s}^{-1}{{{\Omega }}}_{a})\ \ \ .$$
(6)
The numerator and denominator of this expression were efficiently computed by taking their transpose and considering all single-grid Ωa at once, i.e., by replacing Ωa with diags). The mean Ωb-volume-averaged re-exposure time Γ is obtained in the same way but with Ts replaced by its adjoint $${\widetilde{{\bf{T}}}}_{s}$$.
## Data availability
The OCIM2-48L output data used in this study are available in the Figshare database under accession code https://doi.org/10.6084/m9.figshare.1480273270. The global tidal energy dissipation maps used to construct the three-dimensional κ field are available in the SEANOE database under accession code https://doi.org/10.17882/7308271.
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## Acknowledgements
We acknowledge funding from ARC grant DP210101650 (M.H.) and NSF grant OCE-1948955 (T.D.). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 821001 (C.d.L.).
## Author information
Authors
### Contributions
All authors conceived of the study. C.d.L. provided the vertical diffusivity field and T.D. performed the OCIM optimizations. M.H. calculated the transport diagnostics and wrote the manuscript with input on analysis and interpretation from all authors.
### Corresponding author
Correspondence to Mark Holzer.
## Ethics declarations
### Competing interests
The authors declare no competing interests.
Peer review information Nature Communications thanks Graeme MacGilchrist, Sabine Mecking and other, anonymous reviewers for their contributions to the peer review. Peer review reports are available.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Holzer, M., DeVries, T. & de Lavergne, C. Diffusion controls the ventilation of a Pacific Shadow Zone above abyssal overturning. Nat Commun 12, 4348 (2021). https://doi.org/10.1038/s41467-021-24648-x
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2021-09-23 09:55:17
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https://meta.mathoverflow.net/questions/2155/how-should-we-react-to-the-existence-of-math-educators-se/2180#2180
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# How should we react to the existence of Math Educators SE?
As was previously announced at meta, there is now an SE site for mathematics education (MESE). My broad questions is this: Should we react to this somehow? (More specific questions are below.)
Does the MESE site change what education related questions are on-topic here? An earlier meta discussion suggests that questions about mathematics education research are generally off-topic, whereas such questions are on-topic at MESE. Is teaching mathematics at university level always on-topic at MO?
There are teaching related tags here at MO (, ). Should we add a note about MESE in the tag wiki excerpts of educational tags? This is not only about keeping MO clean from off-topic questions, but also about helping people find the best place to ask their questions. The exact wording of such a note could be anything from "There is also a separate StackExchange site for mathematics education: ..." to "Questions about mathematics education are no longer on-topic here. Please ask at ... instead".
Our help pages describe what is on-topic here and mention some other sites for other mathematical questions. Math.SE is included in the list (as it should), but MESE is not. Should we add it? If yes, how should it be worded?
I realize that this question is quite long and contains several different questions. If you think it would be better to split this in several pieces, let me know.
• There are many who participate in both forums. I think the usual guidance given to questions that are better suited elsewhere is applicable to questions suited for ME.SE. Tweaking the help pages to include it is good. Migrating historical ME questions from MO is not good. Spreading awareness of ME.SE in a low-key fashion is good. Reacting as if to anticipate a serious problem is not good: I don't think conditions are such that any strong or even mild reaction to ME.SE's presence is required. Just go about as usual, and refer to the other forums as needed. Feb 28 '15 at 5:32
• @TheMaskedAvenger, I agree that there is not big alarming issue that we should be reacting to. Migrating old questions would be an overkill. My original thought was that spreading the word is a sufficient reaction, but there are several ways to do that. There are many who participate in both forums and word gets around, but there are always new people looking for a place for their questions, too. Feb 28 '15 at 5:52
• This question now shows up on the list of hot meta posts, which looks like excellent advertisement for MESE. Feb 28 '15 at 19:56
• @TheMaskedAvenger: Merely for completeness let me add that in any case, migrating questions that are older than 60 days is impossible, even for moderators. And, while there is a procedure of seeding new sites with old questions from other sites, this is either done at the very start or not at all.
– user9072
Feb 28 '15 at 22:34
• @AsafKaragila, did you know that comments on meta are not meant solely for humorous remarks? :) Mar 4 '15 at 16:37
• Joonas, that doesn't sound right. Are you sure about that? :-)
– Asaf Karagila Mod
Mar 4 '15 at 16:43
• @Asaf, I'm almost sure, but I could of course be mistaken. :-) Maybe you should ask this at meta if you are not afraid of losing an excuse for bad jokes. Mar 4 '15 at 17:00
• I am okay with plausible deniability. :-P
– Asaf Karagila Mod
Mar 4 '15 at 17:03
I am against making "questions on math education no longer on-topic here". There are some excellent education related questions on this site. We may specify that education questions on MO should be related to graduate level (research) education. Graduate-level education is done by professional mathematicians not by professional teachers, and it is natural to have these questions on this site.
Same applies to history of mathematics questions. There is another SE on History of Math and Sciences. Nevertheless there are history questions which are more suitable for this site, the site for professional mathematicians.
Also, on my opinion some questions can be interesting for both audiences in which case they can be posted on both sites, what is wrong with that?
For example, once I posted the same question in MO and in HSM:
When exactly and why did matrix multiplication become a part of the undergraduate curriculum?
and it is my highest scoring question in both MO and HSM.
• I totally agree. If a question is of considerable interest on several sites, I see no obstruction for posting it on all of them, as long the cross-posts are linked. Mar 3 '15 at 4:35
• In general I have a positive opinion towards the idea of reasonable cross-posting. However, I would only add that I think it is almost always better to; a) not post at the exact same time, but with a delay of a couple of days, b) to ask variations of the question on the different sites (as opposed to just copy-paste). Especially, if one does a) the latter question might already be informed by answers to the former.
– user9072
Mar 4 '15 at 12:00
• Since link to the MO question is mentioned in the post, perhaps it might be useful to add also a link to the HSM question: When exactly (and why) did matrices become a part of the undergraduate curriculum? (HSM was also mentioned in this answer: Is there a consensus on whether history of mathematics questions are acceptable on MO?) May 19 '20 at 7:33
• @Martin Sleziak: thanks for your suggestion. I will add the link. May 19 '20 at 12:39
I would very much like to keep questions about graduate level courses here at MO. There is a lot of knowledge of how to present various topics which isn't available in books and is only known to a few experts in the field, and I don't think those questions would get answered at matheducators. Here are some recent questions of mine of that sort. 1 2 3
• I think you want to say "... about topics in graduate level courses". There are general questions that could apply to many graduate level courses that would have varying levels of being on/off topic in both fora. I agree with you that topic specific questions are better here on MathOverflow, but there are non-topic-specific questions about graduate level courses that are better suited for MathEducators. Gerhard "Pigeonholing Helps Organize My Mind" Paseman, 2015.03.05 Mar 5 '15 at 18:28
• Somewhere between the two I think. I want questions of the form "How should I teach graduate level topic $X$ in the context of a course where we have covered $Y_1$, $Y_2$ and $Y_3$, but not $Z_1$ or $Z_2$?" This is a different sort of question than simply "What are some ways/the best way of thinking about $X$?" Mar 9 '15 at 16:01
The Math Educators (MESE) site is still in beta, so there are a few things we can't do just yet. During the beta phase, SE sites are still defining themselves and narrowing down what is on-topic/off-topic for the site. It's best for other SE sites to avoid interfering with this process. For example, we can't establish a migration path to MESE. (Though moderators can still migrate questions to MESE and users can recommend this through moderator flags.) The best we can do for now is to encourage people to use MESE and help the site grow!
The tag does mention MESE. The tag doesn't, but it does reference the tag. I think this is the right way to go about it. Teaching will never be entirely off-topic on MO. Topic divisions are always fuzzy and some teaching-related questions will remain perfectly on-topic for MO even if they might also be on-topic for MESE. However, once MESE grows out of beta, we will probably not see many questions where and are used as primary tags.
• Would it be premature to mention MESE at our help pages before it goes out of beta? I think the difference of the scopes of the two sites is reasonably well defined even if MESE hasn't fully decided what is on-topic there. Feb 28 '15 at 19:49
• You make Stack Exchange sound like a petri dish. Mar 3 '15 at 11:32
Since the contents of the help pages have not been discussed in the answers so far, let me propose a text in the spirit of the other answers. Here is a suggestion for another item in the list of things MathOverflow is not (in our help pages):
• MathOverflow is not for most questions about mathematics education. We recommend asking questions about the process of learning and teaching mathematics at matheducators.stackexchange.com, a site dedicated to this purpose. However, questions about teaching mathematics at graduate or similar level are welcome.
I would place it between "MathOverflow is not for homework help" and "MathOverflow is not a discussion forum". This note about education and MESE is easiest to find if it is included in the list instead of being inserted to some other paragraph.
I think it would be better not to make this mention about MESE and teaching overly specific, but to only give the general idea. The change can be done before MESE goes out of beta, since the general purpose of the site is already clear.
Does this look reasonable?
• Thanks for your initiative. I do not want to get too involved, personally, to avoid the appearance of a conflict of interest. But I would prefer the "professional teachers, professional mathematicians" dichotomy would not make it into the documentation. I know you took it from Alexandre Eremenko's answer and I understand what he means. Still I would prefer to avoid implying there that users here in general are not professional teachers and that users on MESE in general are not professional mathematicians. Finally, "the process of learning" is possibly more clear than "learning."
– user9072
Mar 11 '15 at 1:12
• @quid, thanks! I edited the suggestion. I begin to agree that the dichotomy need not be there, but I do think that something like "teaching by professional mathematicians" is a criterion we should include. Mar 11 '15 at 2:04
• I think "teaching by professional mathematicians" is confusing. I think it is rather common that people working at (research) universities teach over the full spectrum of courses offered, that is first year undergraduates (possibly not even in math) up-to research oriented courses for PhD students. The intent of "other mathematical education offered by professional mathematicians" is not quite clear to me. Is it "about teaching graduate-level courses and other teaching of advanced mathematics" or something else?
– user9072
Mar 11 '15 at 10:05
• @quid, I think advanced mathematics is too vague. A physics major probably has their opinion of what is advanced mathematics but it doesn't match the idea most people here have. I hope "graduate or similar level" conveys the right idea to most people. Also, as teaching mathematics is not only about giving courses (at least for me), I prefer teaching mathematics to teaching courses. But you are right, my expression was not quite clear. I edited again. Mar 11 '15 at 15:21
• I agree the advanced was not a good way to phrase things. I think the current formulation is better.
– user9072
Mar 11 '15 at 15:46
May I suggest this site attempt to collaborate with Math Educators SE to narrow the gap between high school and university math.
A first step in this direction would be to begin a list of the most common weaknesses that Proffessors and teaching assistants observe in incoming freshmen students. This list can then be further discussed at Math Eductators SE.
• That is an interesting question, and in fact it inspired me to ask a question at MESE: matheducators.stackexchange.com/q/7597/2074 The problem is presumably of interest to many MO users, but I think the discussion would be better suited at MESE. I don't see a need for collaboration in this matter besides having users that use both MO and MESE. The problem is about teaching mathematics to freshmen, and I would say that is below the scope of teaching questions at MO. Mar 12 '15 at 16:54
• Thanks, and you have inspired me to ask your question on MSE. Unfortunately, it's not being very well received :( Mar 12 '15 at 18:14
• Maybe that's because there already was a somewhat similar question at MSE meta: meta.math.stackexchange.com/q/19772/166535 Your meta question has now four votes to close. Your question seems to propose collaboration, whereas this question is more about adapting MO policies to the new situation. Mar 12 '15 at 21:09
• The first part of my question simply asks how should MSE's reaction to the existence of MESE be any different than math-overflow's, this would nessesarily include adaptations of existing MSE policies to the new situation. I am asking the policy makers to compare and contrast any similarities and differences between the two sites and why those should be implemented? The second part of my question is merely my point of view on addressing a real-word global problem in the transition from high school to university that we can try to address within this network by a more collaborative approach. Mar 13 '15 at 1:13
• I know. I just wanted to try to find reasons why it got so many downvotes and was closed so quickly without any feedback. The response was so hostile that I doubt there is any chance to reopen it. Mar 13 '15 at 1:42
• How can the exact same question be treated so differently? Mar 13 '15 at 5:05
• The questions were not exactly the same, and there already was a question about MESE at MSE meta. Your question has now two votes to reopen, so it is possible (although not sure) that it would get an answer. Let's see what happens... Mar 13 '15 at 5:19
• Do you have any suggestions on how I should make the question more focused? Mar 13 '15 at 11:31
• The main thing I would improve is to make it more specific what you mean by "react". My question asks specifically about tags, changes in being on-topic (this was already discussed at MSE), tags and help pages. But let us not discuss this here anymore, as this comment discussion doesn't really belong to this meta. (There are now 4/5 reopen votes.) Mar 13 '15 at 16:19
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2021-10-24 19:17:51
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https://www.studyadda.com/index.php?/question-bank/7th-class/mathematics/exponents-and-power/exponents-and-powers/2366
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# 7th Class Mathematics Exponents and Power Question Bank
### done Exponents and Powers
• A) $25$
B) $0$
C) $-25$
D) $1$
• A) $\frac{9}{2}$
B) $\frac{2}{9}$
C) ${{\left( \frac{2}{3} \right)}^{8}}$
D) $\frac{27}{8}$
• A) $10\times {{10}^{11}}={{100}^{11}}$
B) ${{2}^{3}}\times {{3}^{2}}={{6}^{5}}$
C) ${{2}^{3}}>{{3}^{2}}$
D) ${{p}^{0}}={{1000}^{0}}$
• A) $\frac{1}{2}$
B) $2$
C) $4$
D) $\frac{1}{4}$
• A) $3$
B) $234$
C) $1$
D) $24$
• A) $7500$
B) $16000$
C) $11200$
D) $14000$
• ${{(-1)}^{3}},\,{{(-10)}^{3}},{{(1)}^{5}}$ and ${{(-1)}^{4}}$
A) ${{1}^{5}}$
B) ${{(-10)}^{3}}$
C) ${{(-1)}^{4}}$
D) ${{(-1)}^{3}}$
• A) ${{a}^{3}}{{c}^{3}}{{d}^{3}}$
B) ${{a}^{3}}{{c}^{3}}d$
C) ${{a}^{3}}{{c}^{3}}{{d}^{2}}$
D) ${{a}^{3}}{{c}^{4}}{{d}^{2}}$
• A) $2$
B) $4$
C) $6$
D) $-2$
• A) ${{({{2}^{3}})}^{2}}$ and ${{({{3}^{2}})}^{4}}$ are not the same.
B) ${{({{2}^{3}})}^{2}}$ and ${{({{3}^{4}})}^{2}}$ are the same.
C) ${{({{7}^{50}})}^{2}}={{7}^{502}}$
D) ${{({{5}^{7}})}^{3}}={{5}^{73}}$
• A) ${{\left( \frac{6}{5} \right)}^{5}}$
B) ${{({{5}^{6}})}^{5}}$
C) $\frac{{{5}^{5}}}{{{6}^{5}}}$
D) ${{({{5}^{5}})}^{6}}$
• (i) ${{1}^{4}}$ (ii) ${{4}^{0}}$ (iii) ${{0}^{4}}$ (iv) ${{4}^{1}}$
A) (i) and (ii)
B) (ii) and (iii)
C) (i) and (iii)
D) (i) and (iv)
• A) $5$
B) $7$
C) $8$
D) $12$
• A) $\frac{-{{2}^{3}}}{{{m}^{3}}}$
B) ${{\left( -\frac{2}{m} \right)}^{3}}$
C) $\frac{{{(-2)}^{3}}}{{{m}^{3}}}$
D) $-\left( \frac{2}{m} \right)\left( \frac{-2}{m} \right)$
• A) $1$
B) $2$
C) $3$
D) $4$
• A) $36$
B) $42$
C) $46$
D) $48$
• A) ${{2}^{5}}\times {{3}^{4}}$
B) $\frac{{{2}^{5}}\times {{3}^{3}}}{5}$
C) $\frac{{{2}^{6}}\times {{3}^{3}}}{{{5}^{3}}}$
D) $\frac{{{2}^{6}}\times {{3}^{3}}}{{{5}^{2}}}$
• A) $6.59\text{ }x{{10}^{6}}$
B) $6.595\text{ }x{{10}^{5}}$
C) $6.595\text{ }x{{10}^{4}}$
D) $6.59\text{ }x{{10}^{5}}$
• A) ${{5}^{6}}$
B) ${{5}^{4}}$
C) ${{5}^{8}}$
D) ${{5}^{7}}$
• A) $8$
B) $1$
C) 4
D) $0$
• A) $1024$
B) $512$
C) $256$
D) $\frac{1}{512}$
• A) $\frac{1}{5}{{\left[ \frac{{{n}^{2}}}{m{{6}^{10}}} \right]}^{1/3}}$
B) $\frac{1}{5}{{\left[ \frac{n}{{{m}^{2}}{{6}^{10}}} \right]}^{1/3}}$
C) $\frac{1}{5}{{\left[ \frac{{{n}^{2}}}{m{{6}^{-10}}} \right]}^{1/3}}$
D) $\frac{1}{5}{{\left[ \frac{{{n}^{2}}}{m{{6}^{10}}} \right]}^{2/3}}$
• A) $x=\frac{6}{7}$
B) $x=\frac{-7}{6}$
C) $x=\frac{7}{6}$
D) $x=\frac{-6}{7}$
• ${{\left( \frac{6}{7} \right)}^{-2}}\times {{\left( \frac{7}{6} \right)}^{-2}}$
A) $\frac{7}{6}$
B) $1$
C) $\frac{-6}{7}$
D) $\frac{6}{7}$
• A) ${{p}^{3}}{{q}^{4}}{{r}^{7}}$
B) ${{p}^{3}}{{q}^{4}}{{r}^{10}}$
C) ${{p}^{-9}}{{q}^{2}}{{r}^{-4}}$
D) ${{p}^{9}}{{q}^{-2}}{{r}^{4}}$
• A) $64$
B) $256$
C) $1$
D) ${{4}^{-3}}$
• A) ${{a}^{2m(n-2)}}$
B) ${{a}^{2m(2n-4)}}$
C) ${{a}^{-2m(n+2)}}$
D) ${{a}^{2m(n-4)}}$
• A) $120\,\,{{a}^{\frac{25}{4}}}$
B) $\frac{1}{120\,{{a}^{\frac{25}{4}}}}$
C) $24{{a}^{\frac{-25}{4}}}$
D) $24{{a}^{\frac{25}{4}}}$
• A) ${{6}^{5}}\,{{7}^{2}}$
B) $\frac{{{6}^{5}}}{{{7}^{2}}}$
C) ${{6}^{-5}}\,{{7}^{2}}$
D) ${{6}^{-5}}\,{{7}^{-2}}$
• A) $x=\frac{3}{4}$
B) $x=\frac{2}{3}$
C) $x=\frac{5}{6}$
D) $x=\frac{3}{2}$
• ${{({{5}^{3}})}^{x}}\times {{({{5}^{8}})}^{x}}={{5}^{72}}$
A) $x=6\frac{6}{11}$
B) $x=9$
C) $x=6$
D) $x=8$
• A) ${{a}^{11}}{{b}^{18}}{{c}^{-15}}$
B) ${{a}^{11}}{{b}^{18}}{{c}^{15}}$
C) ${{a}^{-11}}{{b}^{-18}}{{c}^{15}}$
D) ${{a}^{-11}}{{b}^{18}}{{c}^{-15}}$
• A) $5.976\times {{10}^{24}}\,kg$
B) $5.976\times {{10}^{21}}\,kg$
C) $5976\times {{10}^{21}}\,kg$
D) $59.76\times {{10}^{23}}\,kg$
• A) ${{(-5xy)}^{6}}$
B) ${{(-5xy)}^{8}}$
C) ${{(-5xy)}^{4}}$
D) ${{(-5xy)}^{2}}$
• A) ${{(3-2)}^{235}}$
B) ${{(-1)}^{47}}$
C) Both [a] and [b]
D) Neither [a] nor [b]
• ${{(-3p)}^{4}}{{(6q)}^{5}}{{(3r)}^{6}}$
A) ${{(-3)}^{15}}{{2}^{5}}{{p}^{4}}{{q}^{5}}{{r}^{6}}$
B) ${{p}^{4}}\,{{q}^{5}}\,{{r}^{6}}$
C) ${{3}^{15}}\,{{2}^{5}}\,{{p}^{4}}\,{{q}^{5}}\,{{r}^{6}}$
D) ${{(-3)}^{15}}\,{{2}^{5}}\,{{p}^{4}}\,{{q}^{4}}\,{{r}^{4}}$
• A) $3.0\times {{10}^{8}}\,m{{s}^{-1}}$
B) $3.0\times {{10}^{10}}\,m{{s}^{-1}}$
C) $3.0\times {{10}^{6}}\,m{{s}^{-1}}$
D) $3.0\times {{10}^{12}}\,m{{s}^{-1}}$
• A) Both are equal.
B) ${{2}^{3}}$
C) ${{5}^{2}}$
D) Cannot be determined.
• A) $x=4$
B) $x=-2$
C) $x=-3$
D) $x=2$
• A) ${{2}^{-3x}}$
B) ${{2}^{8x}}$
C) ${{2}^{3x}}$
D) ${{2}^{11x}}$
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2018-04-24 00:45:47
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https://math.stackexchange.com/questions/696746/why-use-differentials-to-compute-error
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# Why use differentials to compute error?
I get how to use differentials to compute error, but why is it a "good" method? For example, a standard problem is something like:
If the radius of a circle is $3 \pm 0.1$ cm, find the area with error.
What's wrong/undesirable with just finding the area for $r=2.9$ and $r=3.1$ to determine the error?
• In some cases, the maximum error might not occur at the maximum deviation from the given value. To give a pathological example, find the error of the function $$f(x)= \frac{1}{x-2}$$ on the interval $2.1\pm 0.2$. The biggest error (so to speak, I guess) occurs at $x-2$, which is not an endpoint of the error interval. – Ian Coley Mar 2 '14 at 21:24
• @IanColey I disagree: simply calculate the increment $\Delta f(x) = f(2.1) - f(2.1 \pm 0.2)$ and see which of the two errors is the largest. If the input is 2.3, then the error is $10-3.33=6.67$, and if the input is 1.9, the error is $10- (-10)=20$. Clearly, the latter yields the largest error. This has the additional benefit of avoiding figuring out what the derivative of $f(x)$ is. – Ius Klesar Jun 13 at 11:26
The nice thing about using differentials is that as you adjust the error, you don't need to compute the highest and lowest again; you just need to multiply some coefficient.
So, for your example, we might have a situation where we ask "if the radius $3 \pm 0.1$ cm, what's the error?" But the more useful question is "if we want the area to be within $.01$ of $3 \text{cm}^2$, how small does the error in the radius need to be?" In this case, we could solve for $\Delta r$, saying that if our radius is $3 \pm \Delta r$ cm, then $$\Delta A \approx 2 \pi (3 \text{cm})\Delta r \leq .01 \text{cm}$$ and solve for $\Delta r$.
On the other hand, doing things the other way, we would have to solve something like $$\Delta A = \pi (3\text{cm} + \Delta r)^2 - \pi (3\text{cm})^2 \leq .01 \text{cm}$$ In this situation, we simply have a quadratic equation, but in others we could wind up with something much more complicated.
If I understand your question correctly, there are a couple of reasons I can see. First, you can use a general formula instead of computing with specific numbers. Second, you can usually see how the error in measuring (say) $r$ affects the error in the computed value of $A(r)$.
For $A(r)=\pi r^2$, if the measured radius is $r\pm\epsilon$, then the computed area is $A(r\pm\epsilon)\approx A(r) \pm A'(r)\epsilon= \pi r^2\pm 2\pi r\epsilon$. This shows that the error in area is about $2\pi r$ times the error in measuring the radius.
I hope that's the sort of thing you were looking for.
Sometimes you cannot compute the error exactly. For instance, how do you compute the cubic root of 28? If you have a calculator, it is easy. Or you can do it by hand noting that $\sqrt[3]{27}=3$. Let $f(x)=\sqrt[3]{x}$. Then $$f'(x)=\frac{1}{3\sqrt[3]{x^2}}$$ and $$\sqrt[3]{28}=f(27+1)\approx f(27)+1\cdot f'(27)=3+\frac{1}{3\sqrt[3]{27^2}}=3+\frac{1}{27}.$$
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2020-09-25 14:45:41
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http://math.stackexchange.com/questions/269278/an-algebraic-equation-xn-x-a
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# An algebraic equation; $x^n -x =a$
Let $n\ge 2$ be an integer and $a$ be a real number such that $|a|\le (n-1)n^{-\frac n{n-1}}$. Can we find the real solutions of the algebraic equation $$x^n -x =a.$$
-
First, if $n$ is odd, then $f(x) = x^n-x$ is unbounded above and below, and so $f(x)=a$ has a solution for any $a$.
If $n$ is even, $f(x)$ is unbounded above and is convex, since $f''(x) = n(n-1)x^{n-2}\geq 0.$ Any local minimum of $f$ is therefore its global minimum.
Step 1: Find the global minimum of $f$ by solving $f'(x) =0.$
Step 2: What is the value of $f$ at this minimum?
Step 3: What can you conclude about the range of $f(x)?$
In neither case will you in general be able to solve for $x$ analytically.
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You can find closed-form solutions; they'll just be terribly complicated, and will involve special functions... – Ｊ. Ｍ. Jun 1 '13 at 5:37
Yes! I want a closed form. Thank you! – Chung. J Jun 1 '13 at 16:15
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2015-04-20 01:14:40
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http://math.stackexchange.com/questions/36581/matlab-double-integral
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# Matlab double integral
I'm trying to solve a nonlinear system of algebraic (not differential) equations which involves double integrals. I want to use Matlab. There seems to be two functions that can do double integration: dblquad and quad2d.
I noticed that the latter is much faster than the former (100+ times). But I don't know the accuracy. I used both functions to evaluate my integrals (which involves bivariate normal density) and got different answers. I chose a rectangular region around the mean in both cases, since Matlab (I think most numerical algorithms) seems to have difficulty finding the substantial values of the integrand if the region is too big and gives me 0.
My question is: does anyone know the difference of these two functions (in terms of integrating mechanism) as well as accuracy?
Thanks.
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Did you make sure you exploited any symmetry in your integrands? The problem with the cubature of products of Gaussians is that if the peak is too small, sampling might miss it, which is supposed to contribute to the bulk of the integral. Could you maybe post the function you're trying to integrate? – Guess who it is. May 3 '11 at 4:03
What I'm trying to integrate is $E[c((a_1X_1)^{\alpha_1}+(a_2X_2)^{\alpha_2})X_1^{\alpha_1}]$ where $(X_1,X_2)$ is bivariate normal (correlated) and $c$ is some piecewise linear/quadratic function. – GWu May 3 '11 at 4:09
Note that dblquad is essentially a Cartesian product version of quad (i.e., think of computing the double integral by using quad with an integrand whose expression also involves quad), and thus is likely to be slow (due to the adaptive nature of quad) if the integrand has a lot of "features". – Guess who it is. May 3 '11 at 4:10
Anything special about the $a_i$ and the $\alpha_i$? – Guess who it is. May 3 '11 at 4:11
I double checked using Mathematica function NIntegrate[]. In that case, I simply integrate over the whole plane and don't have to choose a smaller integration region. It seems that Mathematica agrees with dblquad. But that too slow for solving my system because it calls the function many times. – GWu May 3 '11 at 4:13
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2015-05-23 08:51:24
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https://socratic.org/questions/57eeb43511ef6b0fcf437b98
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# Question 37b98
Oct 3, 2016
The FPS units of measurement are the foot, pound, and second.
#### Explanation:
The FPS (foot–pound–second) system is built on three fundamental units:
• foot for length
• (avoirdupois) pound for mass
• second for time.
Foot
The foot is defined as being equivalent exactly to 0.3048 m.
One foot represents a length of twelve inches, and three feet equal one yard.
Avoirdupois Pound
The international avoirdupois pound is defined as exactly 0.453 592 37 kg.
One pound is divided into sixteen ounces.
Second
The second is defined as the time that elapses during "9.192 631 770" × 10^9 vibrations of the radiation produced by a transition between two levels of the cesium-133 atom.
There are sixty seconds in a minute, sixty minutes in an hour, and twenty-four hours in a day.
The SI
The corresponding SI units are the metre, kilogram, and second.
Metre
The metre is defined as the distance traveled by light in a vacuum
in $\frac{1}{\text{299 792 458}}$ seconds.
Kilogram
The kilogram is defined as being equal to the mass of the International Prototype Kilogram (IPK), a platinum-iridium cylinder that is kept in a high-security vault outside Paris.
1 kg = 1000 g, and 1 g = 1000 mg
Second
The definition of the second is the same in both the FPS system and the SI.
The Big Differences
(a) FPs is not coherent
In a coherent system of units, all derived units are derived by simple multiplication or division without only "1" as a proportionality factor.
For example, in the SI, the standard unit of volume is "1 m"^3".
In the FPS system, the gallon is not equal to a cubic yard or the cube of any length unit.
(b) SI fractions and multiples of units are expressed as powers of 10.
1 km = 1000 m; 1 m = 1000 mm, etc.
In the FPs system, 1 mi = 1760 yd; 1 yd = 3 ft; 1 ft = 12 in.
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2022-01-23 08:40:16
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https://www.physicsforums.com/threads/parameterizing-a-circle-projected-onto-a-plane.554186/
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# Parameterizing A Circle Projected onto a Plane
1. ### TranscendArcu
288
1. The problem statement, all variables and given/known data
Find a vector function that parameterizes a curve C which lies in the plane x-y+z=2 and directly above the circle x2 + (y-1)2 = 9
3. The attempt at a solutionSo, in order to parameterize the circle, I simply use x=cos(t), y = sin(t) with some adjustments. Namely, I let x=3cos(t) and y=3sin(t)+1. Then, to determine how the z-coordinates of this curve change according to x,y I use the definition of the plane. So I have z=2-x+y, which I convert using my parametric defintions for x,y.
I have, z=3-3cos(t)+3sin(t). Therefore, my parameterized curve is,
<3cos(t),3sin(t)+1,3-3cos(t)+3sin(t)>
Right?
2. ### I like Serena
6,194
Looks good.
But... is it always above the circle?
3. ### TranscendArcu
288
So I just drew myself a little sketch. Basically I have plane and, beneath it, a cylinder which extends upwards, whose base represents the circle. The intersection of the cylinder and the plane should be the projection of the circle onto the plane, right? In this case, I can't see how the projection could be anywhere else besides over the circle.
As an aside, the vector projection of a onto b is given as follows:
((b [dot] a)/|a|) * a/|a|.
Is it possible to use the idea of projections along with dot products to solve this problem?
4. ### I like Serena
6,194
Consider t=-pi/4.
Is the corresponding point above or below the circle?
This is the formula for projection onto a line.
It doesn't work for projection onto a plane.
Anyway, you still need a parametrization.
The only catch is that the curve is not entirely above the circle (assuming the problem does make this fine distinction).
5. ### TranscendArcu
288
OH! I see what you mean now. So presumably I need only calculate a z-coordinate for above/below orientation:
z=3-3cos(t)+3sin(t), where t=-pi/4
z=3-3sqrt(2).
So I understand that this point is below the xy-plane, but I don't understand how this impacts the parametrization. Does it change how I am allowed to define t? If the intersection of my cylinder with the plane is still the projection, what difference does "above" or "below" make?
6. ### I like Serena
6,194
Well, as I interpret the problem (and I may be wrong), it asks for a parametrization that is "above" the circle.
So I think you're supposed to limit the range of t, such that the curve is indeed "above" the circle.
But perhaps I'm being too nit-picky. You tell me.
Still, it is good practice...
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2015-05-28 18:20:31
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http://mathematica.stackexchange.com/questions/9111/what-function-can-i-use-to-evaluate-xy2-to-x2-2xy-y2/9112
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What function can I use to evaluate $(x+y)^2$ to $x^2 + 2xy + y^2$?
What function can I use to evaluate $(x+y)^2$ to $x^2 + 2xy + y^2$?
I want to evaluate It and I've tried to use the most obvious way: simply typing and evaluating $(x+y)^2$, But it gives me only $(x+y)^2$ as output. I've been searching for it in the last minutes but I still got no clue, can you help me?
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Expand[(x + y)^2]
x^2 + 2 x y+ y^2
But I recommend you to look at the following tutorials.
And of course a super tutorial:
Also this palette maybe really useful: Top Menu >> Palettes >> Other >> Algebraic Manipulation
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I've found it in the same time you answered. Haha – Gustavo Bandeira Aug 5 '12 at 6:10
@GustavoBandeira Nope. Vitaliy won by 6 seconds – belisarius Aug 5 '12 at 6:11
@belisarius I feel Olympics spirit ;-) – Vitaliy Kaurov Aug 5 '12 at 6:13
Congratulations! – Gustavo Bandeira Aug 5 '12 at 6:15
@OleksandrR. Maybe to evaluate sub-expressions? One can select self-sufficient part of expression and evaluate it leaving the larger context untouched. – Vitaliy Kaurov Aug 6 '12 at 17:59
Collect
Since it hasn't been mentioned (and one can interpret the question in another way) I'd recommend to use also Collect (it can be applied not only to polynomials) :
Collect[(x + y)^2, x]
x^2 + 2 x y + y^2
In more general cases it would be handy to use the second argument in the form of List, e.g. Collect[(x + y)^2, {x, y}]. Comparing it to Expand let's try Collect with PolynomialForm :
Collect[(x + y + z)^3, x] // PolynomialForm[ #, TraditionalOrder -> True] &
x^3 + (3 y + 3 z) x^2 + (3 y^2 + 6 z y + 3 z^2) x + y^3 + z^3 + 3 y z^2 + 3 y^2 z
it collects terms with various powers of x only, while this expands terms with positive integer power in the expression :
Expand[(x + y + z)^3]
x^3 + 3 x^2 y + 3 x y^2 + y^3 + 3 x^2 z + 6 x y z + 3 y^2 z + 3 x z^2 + 3 y z^2 + z^3
Expand
It could be useful to take a look at the second argument of Expand e.g.
Expand[(x + y)^2 + (y + z)^2, x]
x^2 + 2 x y + y^2 + (y + z)^2
it leaves unexpanded terms free of x.
Edit
Let's add another functions which can also expand polynomials ( they serve different purposes though ) like :
GroebnerBasis
GroebnerBasis[(x + y)^2, x][[1]]
x^2 + 2 x y + y^2
And @@ ( GroebnerBasis[(x + y + w + z)^#, x][[1]] == Expand[(x + y + w + z)^#] & /@ Range[2, 10])
True
PolynomialReduce
PolynomialReduce[(x + y)^2, 1, x][[1, 1]]
x^2 + 2 x y + y^2
And @@ ( PolynomialReduce[(x + y + w + z)^#, 1, {x, y, w, z}][[1,1]]
== Expand[(x + y + w + z)^# ] & /@ Range[2, 10])
True
-
You might also try:
Apart[(x + y)^2]
x^2 + 2 x y + y^2
-
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2013-06-19 04:43:59
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https://chemistry.stackexchange.com/questions/111726/the-action-of-nitrogen-iodide-on-methyl-ketones
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# The Action of Nitrogen Iodide on Methyl Ketones
I recently encountered two old publications on action of nitrogen iodide on various compounds (Ref.1 and Ref.2). Between them, Ref.1 described the idoform formation by methyl ketones upon treatment of the conditions:
Ketones containing a methyl group react very readily with nitrogen iodide, iodoform, ammonia, an acid, and an amide being produced. In these reactions the methyl group appears first to be completely substituted by iodine, a tri-iodomethyl ketone being formed, which in presence of the ammonia simultaneously set free is hydrolysed to iodoform and an acid, a similar reaction between the substituted ketone and ammonia leading to the formation of iodoform and an amide.
The reactions were suggested as follows: \begin{align} \ce{RCOCH3 + NH3.NI3 &-> RCOCI3 + 2NH3}\\ \ce{RCOCI3 + H2O &-> RCO2H + CHI3}\\ \ce{RCOCI3 + NH3 &-> RCONH2 + CHI3} \end{align}
This formation of idoform is understandable. Yet, Ref.2 claimed that the authors have obtained idoform from diethylketone (3-pentanone):
Like the other ketones, diethylketone when treated with nitrogen iodide, yields the iodoketones, having very irritable odor. On effecting the interaction in a dilute solution, iodoform is formed in good quantity. It has been observed that as we rise higher and higher in the homologous series of the ketones, the tendency of the formation of iodoform gradually diminishes and the yields also gradually become less.
The reported method the authors had been used: $$\pu{2 mL }$$ of diethylketone are taken in a beaker and diluted with $$\pu{150 mL }$$ of weak ammonia. The mixture is warmed on the water bath, and to it, iodide solution is added when at first nitrogen iodide is precipitated, which is immediately taken up. The addition of iodine has to be continued, and finally a copious yellow crystalline precipitate deposits. This is iodoform. On recrystallization from alcohol, this has been obtained quite pure, melting at $$\pu{119 ^{\circ}C}$$. The yield amounts to $$\pu{0.8 g }$$.
I’m very curious about their claim and like to hear from your theory of mechanism.
Cited References:
1. F. D. Chattaway, R. R. Baxter, “CCX.—The Action of Nitrogen Iodide on Methyl Ketones,” J. Chem. Soc., Trans. 1913, 103, 1986–1988 (DOI: 10.1039/CT9130301986).
2. R.L. Datta, N. Prosad, “Halogenation. XVI. Iodination by Means of Nitrogen Iodide or by Means of Iodine in the Presence of Ammonia,” J. Am. Chem. Soc. 1917, 39(3), 441–456 (DOI: 10.1021/ja02248a013).
• In the second reaction i dont understand the significance of adding iodine continuously. If NI3 is already formed it has a property of dissociating again to I2. Then what is the reason for adding I2? – Som V. Tambe Apr 6 at 9:13
• This question is hard to answer without more details from the two papers. – Zhe Apr 6 at 13:18
• @Zhe hey i have a mechanism which gives us great yields of iodoform. The only problem is the details about dilution. I dont get why they dilute it. – Som V. Tambe Apr 6 at 13:53
• @ KG3: I cannot pinpoint how they distinguish those chemicals. Yet, chemistry is in prictice way before 1917. For example, how would you think Claisen recognized the rearrangement without NMR or IR or MS? It's not easy, but they have done that and results are very fruitful. – Mathew Mahindaratne Apr 11 at 21:57
• @MathewMahindaratne you are completely missing the point. The proposed reaction in reference #2 contradicts the entirety of the literature on the haloform reaction since 1870. Either we should (A) discard all subsequent literature examples that utilize the haloform test to identify methyl ketones as incorrect (B) presume Datta & Prosad made incorrect but completely understandable assumption. If you're going to make extraordinary claims you must supply extraordinary evidence. Claisen did. Datta and Prosad did not. – KG3 Apr 11 at 22:59
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2019-10-16 05:14:29
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https://www.projecteuclid.org/euclid.jdg/1391192694
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## Journal of Differential Geometry
### The skein algebra of arcs and links and the decorated Teichmüller space
#### Abstract
We define an associative $\mathbb{C}[[h]]$-algebra $\mathcal{A}\mathcal{S}_h(\Sigma)$ generated by regular isotopy classes of arcs and links over a punctured surface $\Sigma$ which is a deformation quantization of the Poisson algebra $\mathcal{C}(\Sigma)$ of arcs and loops on $\Sigma$ endowed with a generalization of the Goldman bracket. We then construct a Poisson algebra homomorphism from $\mathcal{C}(\Sigma)$ to the algebra of smooth functions on the decorated Teichmüller space endowed with a natural extension of the Weil-Petersson Poisson structure described by Mondello. The construction relies on a collection of geodesic lengths identities in hyperbolic geometry which generalize Penner’s Ptolemy relation, the trace identities and Wolpert’s cosine formula. As a consequence, we derive an explicit formula for the geodesic lengths functions in terms of the edge lengths of an ideally triangulated decorated hyperbolic surface.
#### Article information
Source
J. Differential Geom., Volume 96, Number 1 (2014), 95-140.
Dates
First available in Project Euclid: 31 January 2014
https://projecteuclid.org/euclid.jdg/1391192694
Digital Object Identifier
doi:10.4310/jdg/1391192694
Mathematical Reviews number (MathSciNet)
MR3161387
Zentralblatt MATH identifier
1290.53080
#### Citation
Roger, Julien; Yang, Tian. The skein algebra of arcs and links and the decorated Teichmüller space. J. Differential Geom. 96 (2014), no. 1, 95--140. doi:10.4310/jdg/1391192694. https://projecteuclid.org/euclid.jdg/1391192694
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2019-09-19 07:16:38
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https://www.zigya.com/study/book?class=12&board=nbse&subject=Biology&book=Biology&chapter=Molecular+Basis+of+Inheritance&q_type=&q_topic=Regulation+Of+Gene+Expression+&q_category=&question_id=BIENNT12134047
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### Chapter Chosen
Molecular Basis of Inheritance
### Book Store
Currently only available for.
CBSE Gujarat Board Haryana Board
### Previous Year Papers
Download the PDF Question Papers Free for off line practice and view the Solutions online.
Currently only available for.
Class 10 Class 12
Differentiation of organs and tissues in a developing organism, is associated with
• developmental mutations
• differential expression of genes
• lethal mutations
• deletion of genes
B.
differential expression of genes
Differentiation of organs and tissues in a developing organism, is associated with differential expression of genes. In regulation of gene expression the chromosomal proteins play an important role. The chromosomal proteins are of two types histones and non-histones. The regulation of gene expression involves an interaction between histones and non-histones.
Differentiation of organs and tissues in a developing organism, is associated with differential expression of genes. In regulation of gene expression the chromosomal proteins play an important role. The chromosomal proteins are of two types histones and non-histones. The regulation of gene expression involves an interaction between histones and non-histones.
How many nucleotides are present in a bacteriophage $\mathrm{\varphi }$ x 174.
5386
Comment two chains of DNA have antiparallel polarity.
The Two chain of DNA are antiparallel that is
if one chain has 5’ x 3’ polarity the other chain has 3’ x 5’ polarity.
List the number of base pairs in :
(i) lambda bacteriophage
(ii) E.coli and
(iii) haploid content of human DNA.
(i) 48502 bp
(ii) 4.6 x 106 bp and
(iii) 3.3 x 109 bp.
Name the genetic material for majority of organisms.
DNA (Deoxyribose nucleic acid)
List the function of RNA.
Functions of RNA
RNA acts as genetic material in viruses
It also functions as an adapter and messenger
It also acts as a catalytic molecule and catalyses various biochemical reactions.
Do a good deed today
Refer a friend to Zigya
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2018-05-21 11:19:56
|
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|
https://www.strickland.cloud/2021/04/01/extern%E5%85%B3%E9%94%AE%E5%AD%97%E7%9A%84%E4%B8%80%E7%82%B9%E6%80%9D%E8%80%83/
|
//foo.c中
int a = 1;
//bar.c中
int a;
int main() {
printf("%d\n",a);
}
However, that is effectively a language extension. Strictly conforming ISO C programs cannot define a name more than once.
As @litb points out here, and as stated in my answer to the cross-referenced question, using multiple definitions for a global variable leads to undefined behaviour, which is the standard's way of saying "anything could happen". One of the things that can happen is that the program behaves as you expect; and J.5.11 says, approximately, "you might be lucky more often than you deserve". But a program that relies on multiple definitions of an extern variable - with or without the explicit 'extern' keyword - is not a strictly conforming program and not guaranteed to work everywhere. Equivalently: it contains a bug which may or may not show itself.
### 这两种方式在文件的表述中是否有些不同的？
With some (indeed, many) C compilers, you can get away with what's called a 'common' definition of a variable too. 'Common', here, refers to a technique used in Fortran for sharing variables between source files, using a (possibly named) COMMON block. What happens here is that each of a number of files provides a tentative definition of the variable. As long as no more than one file provides an initialized definition, then the various files end up sharing a common single definition of the variable:
PS：我在WSL中实验的时候发现readelf -s得到的结果，不会出现，不知道是什么原因。在Linux下重新尝试了下，输出的结果是正常的（就是上图）。
### 如何正确的使用extern关键字
1. 在头文件中带有extern关键词来声明(declaration)变量.
2. 在需要这个变量的.c文件中引用这个头文件
3. 在正式定义这个变量的.c文件中也需要引用这个头文件
如下：
file3.h
extern int global_variable; /* Declaration of the variable */
file1.c
#include "file3.h" /* Declaration made available here */
#include "prog1.h" /* Function declarations */
/* Variable defined here */
int global_variable = 37; /* Definition checked against declaration */
int increment(void) { return global_variable++; }
file2.c
#include "file3.h"
#include "prog1.h"
#include <stdio.h>
void use_it(void)
{
printf("Global variable: %d\n", global_variable++);
}
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2021-09-18 14:14:29
|
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|
https://discourse.julialang.org/t/glm-is-slow-on-large-datasets-using-onlinestats-for-regressions-mixedmodels/17695?page=2
|
# GLM is slow on large datasets. Using OnlineStats for regressions? MixedModels?
#21
I’m not a numeric analyst, but won’t the condition number of (X’ * X) \ (X’ * Y) be the square of that of X \ Y?
It is but it’s usually not a problem in statistical applications. If X is almost rank deficient then you’ll have a lot of uncertainty about the parameter estimates. The amplified noise from the squared condition number will be nothing compared to the statistical uncertainty. In some applications, you expect a perfect fit and in that case it can matter if you use QR or the Cholesky.
#22
Econometrics 101 is a must-have!
#23
Thanks for tip.
Question: in some algorithms (“chemometrics”, etc.), it is common to use PCR (or PLS). PCR essentially chooses the number of latent variables based on the condition number. SVD is convenient because one can play around with \sigma_{i-1}/\sigma_i and find a suitable cut. With a “rank revealing” QR factorization where the diagonal elements of R are sorted in descending order, a similar idea could be used. But the standard QR factorization doesn’t contain a sorting of the diagonal elements of R, right?
#24
That is, of course, a valid point .
#25
This article shows you the equations but doesn’t discuss about the proper numerical methods (such as SVD, QR, Cholesky or sparse matrix methods…) to solve them.
#26
That is correct. You can use QR factorization for this,
invperm(F.jpvt)
Gives you the sorted column ranking.
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2018-12-16 03:20:44
|
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|
http://math.stackexchange.com/questions/215970/the-definition-of-a-normal-subgroup
|
# The definition of a normal subgroup
There are a whole bunch of equivalent definitions of a normal subgroup. Is it logically sound (with respect to the usual definitions) to include as a definition of normal, "$N$ is the kernel of some homomorphism $f$"?
-
Equivalent definitions usually require proof of equivalence. – EuYu Oct 17 '12 at 23:33
This is precisely the first isomorphism theorem. If we define a normal subgroup $N$ to be a subgroup of $G$ such that $gNg^{-1}\in N$ for all $g\in G$ then the first isomorphism theorem states that every normal subgroup is the kernel of some homomorphism and the kernel of every homomorphism is a normal subgroup. Thus, they are equivalent. – user1729 Oct 18 '12 at 11:08
It's logically sound. Let $G$ be group, $N$ a normal subgroup of $G$. $N$ is the kernel of the canonical homomorphism $G \rightarrow G/N$. Conversely let $f\colon G \rightarrow G'$ be a group homomorphism. $Ker(f)$ is a normal subgroup of $G$.
You write "its normal subgroup" -- this would mean a group can only ever have one normal subgroup. If you don't mean it this way you could write something like "$N$ a normal subgroup of $G$". – Rudy the Reindeer Oct 20 '12 at 15:16
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2015-11-25 18:43:21
|
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|
https://craftytrades.com/primer-on-interest-rates/
|
Interest rate is a cornerstone variable in the pricing of nearly all derivatives. This blog post aims to give a brief overview on how interest rates are measured and analyzed with the application to the bond pricing.
An interest rate is usually defined as the cost of the borrowed funds, expressed as a percentage of the loan amount. There is a variety of interest rates for any given currency. Credit risk play the key role in determination of the interest rate applicable in the lending event. It is interpreted as the risk that a creditor will not receive a principal and the interest payment of the funds borrowed. One of the main rates used in finance are:
1. Treasury rates (Rate an investor earns on Treasury Bills and Treasury Bonds)
2. LIBOR rates (A short-term borrowing rate among banks)
3. Repurchase Agreement (A rate for dealers in government securities)
4. The Fed Funds Rate (Overnight rate among banks)
In the derivatives pricing, the so called risk-free rate is used. It is usually argued that a riskless derivatives portfolio should provide the return equal to the risk-free rate. In practice, there is no agreed rate which is used in the context of being risk-free. Depending on the situation, the LIBOR or overnight indexed swap (OIS) rates are used for this purpose. One example of how the OIS is used can be found here.
## Interest Rate Measurements
A compound interest is the main result used in the financial world and has a widely known formula $A_0(1+\frac{r}{m})^{mn}$ where an amount $A_0$ is invested for $n$ years at the interest rate of $r$ per annum. To generalize a result, the compounding frequency $m$ is used (e.g. monthly).
The limit of the compound interest formula as $m$ tends to infinity is called a continuous compounding. It simplifies the formula to $A_0 e^{rn}$
This result is the widely used in the derivatives valuation, especially in the form of the discounting factor $e^{-rn}$. This formula is often used in the context of the $n$-year zero rate (Total rate of interest earned on the investment lasting $n$ years without additional payments).
## Bond Valuation
On of the simplest securities that are priced via interest rates are bonds. Bond holders periodically receive payments called coupons. The face value (known as principal or par value) is received at the bond's maturity. In theory, the price of the bond is equal to the sum of all future cash flows discounted to present by the separate risk-free zero rate. The most popular way to determine the zero rate called bootstrap method and is described here.
Mathematically, price of the bond $B$ with the cash flows $c_i$ paid to the holder at the time $t_i$, where $i=1..n$ and $r(0,t_i)$ is the continuously compounded zero rate is $B=\sum_{i=1}^{n}c_ie^{-r(0,t_i)t_i}$ If the instantaneous interest rate curve r(t) is known, the formula can be expanded to $B=\sum_{i=1}^{n}c_i\space\exp\left ( -\int_{0}^{t_i}r(\tau )d\tau \right )$
### Bond and Par Yields
Bond Yield the constant rate at which the sum of the discounted future cash flows of the bond is equal to the market price of the bond. This rate is found numerically (e.g. Newton method applied to the non-linear equation $B(r)=0$), similarly to the procedure of founding Internal Rate of Return (IRR) in Finance. Par yield is the coupon rate that makes the par value of the bond equal to its price. Another important rate used in finance is called forward rate and is explained here.
### Duration
The duration of the Bond simply measures how long on average the holder of the bond will wait until receiving cash payments. A zero-coupon bond that lasts for $n$ years has a duration of $n$ years, while a bond with coupons has a duration less then $n$ years. The duration, $D$, of the bond is expressed as $D=\sum_{i=1}^{n}t_i\space\left [\frac{c_ie^{-rt_i}}{B}\right]$ with the same definitions as in a mathematical extract on bond valuation.
As can be seen, the duration of the bond is simply the weighted average of the series of payments, where the weight is equal to the present value of the cash flow at the given time point (Discount rate is assumed to be the bond yield). The approximation of the relationship between the yield and the bond price can be provided as $\frac{\Delta B}{B}=-D\Delta r$ where $r$ is the bond yield. It can be further modified to change continuous compounding to any compounding frequency $m$.
One of the application of the duration measure can be the elimination of the exposure to the small changes in the yield curve. By having a portfolio of assets with the same duration as the total liabilities, one can reduce such risk and be vulnerable only to the large shifts in yield curve.
### Convexity
While the approximation formula of the duration given above showing good results with small changes in yield curve, larger moves require more reliable measure to capture bond price changes. When two bond portfolios have the same duration, the large change in the yield curve can result in the different percentage change of the portfolio values. The extent of the curvature of the relationship is known as convexity and is measured as follows $C=\frac{1}{B}\frac{d^{2}B}{dy^{2}}$ If we approximate the series using Taylor expansion, a more reliable measure can be derived $\frac{\Delta B}{B}=-D\Delta r+\frac{1}{2}C(\Delta r)^{2}$ Having a portfolio of assets and liabilities with the same convexity and duration measures, one can be safely protected from a large dynamics of a yield curve.
## Conclusion
For trades utilizing derivatives in their trading, Treasury and LIBOR rates can be reliable used as a proxy to the risk-free rate. Two important concepts when dealing with interest rate products are convexity and duration, which basically measure sensitivity of the bond portfolio to the changes in yield curve. Finally, while the topic can be very technical in nature, the basic understanding is required by all derivatives trades, who wish to expand their knowledge on the valuation of the products they trade. Feel free to suggest topics which you want me to cover in the comments section below!
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2019-09-18 20:33:05
|
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|
https://homework.zookal.com/questions-and-answers/jill-purchased-a-share-for-533-one-year-ago-the-572726869
|
Jill purchased a share for $5.33 one year ago. The share is now worth$10.97. During the year, the share paid a dividend of \$1.06. What is the total return to Jill from owning the share? (as a percentage to the nearest two decimal points; don’t use % sign. eg 2.881% is 2.88.)
|
2021-05-08 14:38:53
|
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|
https://www.physicsforums.com/threads/please-prove-this.207489/
|
1. Jan 6, 2008
### Arham
Hello. I'm learning tensor analysis. I have a problem. We know that
$$\Gamma^i_{jk}=\vec{\epsilon^i}\cdot\frac{\partial\vec{\epsilon_j}}{\partial q^k}$$
$$\frac{\partial\vec{\epsilon_j}}{\partial q^k}=\Gamma^m_{jk}\vec{\epsilon_m}$$
Last edited: Jan 6, 2008
2. Jan 6, 2008
### belliott4488
What'll you pay me?
3. Jan 21, 2008
### hanskuo
$$\Gamma^m_{jk}\vec{\epsilon_m}\cdot\vec{\epsilon^i} =\Gamma^m_{jk}\delta^i{}_m=\Gamma^i_{jk}$$
4. Jan 23, 2008
### Arham
Thanks hanskuo.
I knew this proof, but I thought that it is only correct for the inverse relation. I was wrong!
5. Jan 24, 2008
### hanskuo
you are wellcome, Arham
Now I'm learning Differential Geometry,too.
do you begin to lerane covariant derivatives or not ?
6. Jan 24, 2008
### Arham
I'm an undergraduate physics student, hanskuo. I am learning tensor analysis from George Arfken's book. As you know, this book has a brief introduction to Covariant Derivative; I have read it. But I should do more exercises and read more about it in future.
7. Jan 24, 2008
### hanskuo
There are a lot of things interesting for covariant derivatives.
$$\nabla_{e_i}e_j=\Gamma^k{}_{ij}e_k$$
|
2017-02-22 20:17:42
|
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|
http://cvgmt.sns.it/paper/3107/
|
# Second-order structured deformations: relaxation, integral representation and applications
created by morandott on 08 Jul 2016
modified on 19 Jul 2017
[BibTeX]
Published Paper
Inserted: 8 jul 2016
Last Updated: 19 jul 2017
Journal: Arch. Rational Mech. Anal.
Volume: 225
Pages: 1025-1072
Year: 2017
Doi: 10.1007/s00205-017-1120-5
ArXiv: 1607.02311 PDF
Notes:
Preprint SISSA: 37$/$MATE$/$2016
Abstract:
Second-order structured deformations of continua provide an extension of the multiscale geometry of first-order structured deformations by taking into account the effects of submacroscopic bending and curving. We derive here an integral representation for a relaxed energy functional in the setting of second-order structured deformations. Our derivation covers inhomogeneous initial energy densities (i.e., with explicit dependence on the position); finally, we provide explicit formulas for bulk relaxed energies as well as anticipated applications.
|
2018-10-23 16:30:49
|
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|
https://beginners-guide-to-xmonad.readthedocs.io/configure_stalonetray.html
|
# Configuring Stalonetray¶
Stalonetray is a small “stand-alone” tray, nice easy and simple to use. It’s installed with a simple APT command: sudo apt-get install stalonetray. Like xmobar, it also gets it’s parameters from a file in your home directory called ~/.stalonetrayrc. Also like xmobar, if the file does not yet exist, create it.
Here’s what my stalonetray configuration looks like:
decorations none
transparent false
dockapp_mode none
geometry 5x1-400+0
max_geometry 5x1-325-10
background "#000000"
kludges force_icons_size
grow_gravity NE
icon_gravity NE
icon_size 12
sticky true
#window_strut none
window_type dock
window_layer bottom
#no_shrink false
geometry 5x1-523+0: The first two values, 5x1 are the height and width of the bar (measured in multiples of icon slots, e.g. 5 icons wide and 1 icon high). The next two are the x and y positions.
background "#000000": Black background, to match xmobar.
If you were to run stalonetray right now, most likely it would simply be an empty black bar. With no icons to fill it, it would just blend right in with xmobar. In the next part, however, when we configure the xmonad.hs file, processes will be started on login and will populate stalonetray. Let’s get started!
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2020-02-28 23:25:20
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https://www.physics.uoguelph.ca/problem-11-71-grav-elec-potential-part-2
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# Problem 11-71 Grav & Elec Potential - Part 2 - A
A particular proton in space is subjected to two fields: a gravitational field ($1.30 \times 10^5\; N/kg$ toward planet $X$), and an electric field ($2.47 \times 10^{-4} \; N/C$ away from planet $X$).
(a) If the proton is released from rest, in which direction will it move?
(b) After moving $1.50 \;m$, what will be its speed? Use energy methods and assume uniform fields.
Accumulated Solution
No. You have the variables of electric field and gravitational field confused.
Try again.
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2021-07-26 12:35:32
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http://www.maplesoft.com/support/help/MapleSim/view.aspx?path=DrivelineComponentLibrary/basicGear
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Home : Support : Online Help : MapleSim Toolboxes : MapleSim Driveline Component Library : Simple Gear Sets : Basic Gear Sets : DrivelineComponentLibrary/basicGear
Basic Gear
Basic Gear component
The Basic Gear component models two meshing gears without inertia, elasticity or backlash. Gear and bearing friction inertia may be included by attaching the Inertia and Bearing Friction components to either ‘flange_a’ or ‘flange_b’, respectively.
Kinematic Equation
Where ${r}_{b/a}$ is the gear ratio and is defined as:
${r}_{b/a}=\frac{{N}_{b}}{{N}_{a}}$
Where ${N}_{a}$ is the number of teeth of the a-side gear and ${N}_{b}$ is the number of teeth of the b-side gear. Also, and ${\mathrm{\varphi }}_{b}$ are defined as
, $x$ ∈ $\left\{a,b\right\}$
Where ${\mathrm{\varphi }}_{\mathrm{fa}}$ and ${\mathrm{\varphi }}_{\mathrm{fb}}$ are the absolute rotation angles of flange_a and flange_b, respectively.
Torque Balance Equation (No Inertia)
${\mathrm{τ}}_{b}={r}_{b/a}·\left({\mathrm{τ}}_{a}-{\mathrm{τ}}_{\mathrm{loss}}\right)$
Where and ${\mathrm{\tau }}_{b}$ are the torques applied to flange_a and flange_b, respectively.
Also ${\mathrm{\tau }}_{\mathrm{loss}}$ is the meshing loss torque and is defined as:
Where
${\mathrm{\omega }}_{a}$ =
When useSupport = true, the following equation is added to calculate the support reaction torque:
${\mathrm{\tau }}_{\mathrm{support}}$ =
Power Loss:
The power loss (${P}_{\mathrm{loss}}$) is calculated as:
Connections
Name Condition Description ID ${\mathrm{flange}}_{a}$ - Flange to driver shaft flange_a ${\mathrm{flange}}_{b}$ - Flange to driven shaft flange_b support support $\mathrm{ideal}=\mathbf{false}$ Conditional real output port for power loss lossPower data source = input port Conditional real input port for loss data lossdata
Parameters
Symbol
Condition
Default
Units
Description
ID
$\mathrm{ideal}$
-
$\mathbf{true}$
-
Defines whether the component is:
true - ideal or
false - non-ideal
ideal
data source
$\mathrm{ideal}=\mathbf{false}$
GUI
-
Defines the source for the loss data:
• entered via GUI [data entered via GUI]
• by an attachment [data is attached to model]
• by an external file [data is stored in a file]
• an input port [input port]
datasourcemode
${n}_{\mathrm{inputs}}$
data source = input port
$1$
-
Number of inputs
• One input (${n}_{\mathrm{inputs}}$=1): Forward and backward efficiencies are the same:
• Two inputs (${n}_{\mathrm{inputs}}$=2): Forward and backward efficiencies are given independently:
inputNo
use support
-
$\mathbf{false}$
-
Enables/disables the support flange
useSupport
${r}_{b/a}$
-
$1$
-
Gear ratio
ratio
$\mathrm{η}\left({\mathrm{ω}}_{a}\right)$
data source = GUI
$\left[0,1,1\right]$
$\left[\frac{\mathrm{rad}}{s},-,-\right]$
Defines velocity dependant meshing efficiency
The columns:
[${\mathrm{\omega }}_{a}$ (${\mathrm{\eta }}_{1}$ (${\mathrm{\omega }}_{a}$ ) ${\mathrm{\eta }}_{2}$ (${\mathrm{\omega }}_{a}$ )]
Five options are available:
• 1 by 1 array: entered value is taken as the constant efficiency for forward and backward cases
${\mathrm{\eta }}_{1}$ (${\mathrm{\omega }}_{a}$ ) = ${\mathrm{\eta }}_{2}$ (${\mathrm{\omega }}_{a}$ ) = ${\mathrm{\eta }}_{}$
• 1 by 2 array: first entered value is taken as the constant efficiency for forward case and the second for backward cases
${\mathrm{\eta }}_{1}$ (${\mathrm{\omega }}_{a}$ ) = (${\mathrm{\omega }}_{a}$ ) = ${\mathrm{\eta }}_{2}$
• 1 by 3 array: first column is ignored and the second and third values are taken as constant efficiencies for forward and backward cases, respectively
• n by 2 array: 2nd column is forward and backward efficiency
$\mathrm{η}$ (${\mathrm{\omega }}_{a}$ ) = ${\mathrm{\eta }}_{1}$ (${\mathrm{\omega }}_{a}$ ) = ${\mathrm{\eta }}_{2}$(${\mathrm{\omega }}_{a}$ )
• n by 3 array:
2nd column is forward efficiency
${\mathrm{\eta }}_{1}$ (${\mathrm{\omega }}_{a}$ )
3rd column is backward efficiency
${\mathrm{\eta }}_{2}$ (${\mathrm{\omega }}_{a}$ )
Note: The rows of the array are ordered according to ${\mathrm{\omega }}_{a}$, with the first row having the smallest |${\mathrm{\omega }}_{a}$|
meshinglossTable
data source = attachment
Defines velocity dependant meshing efficiency
First column is angular velocity (${\mathrm{\omega }}_{a}$ )
(See $\left[\mathrm{η}\right]$ below)
data
data source = file
Defines velocity dependant meshing efficiency
fileName
$\left[\mathrm{η}\right]$
data source = attachment or file
$\left[2,3\right]$
-
Defines the corresponding data columns used for forward efficiency (${\mathrm{\eta }}_{1}$) and backward efficiency (${\mathrm{\eta }}_{2}$ )
Two options are available:
• 1 by 1 array:
Data column corresponding to the column number is used for both forward and backward efficiencies ()
• 1 by 2 array:
Data column corresponding to the first column number is used for forward efficiency (${\mathrm{\eta }}_{1}$)
and data column corresponding to the second column number is used for backward efficiency (${\mathrm{\eta }}_{2}$)
columns
smoothness
$\mathrm{ideal}=\mathbf{false}$
Table points are linearly interpolated
-
Defines the smoothness of table interpolation. There are two options:
• Table points are linearly interpolated
• Table points are interpolated such that the first derivative is continuous
smoothness
Note: The ratio (${r}_{b/a}$) must be non-zero. Negative values are permissible. For (${r}_{b/a}$) < 0, the Basic Gear component resembles the Ideal Gear (when ideal = true) and Lossy Gear (ideal = false).
References
Pelchen C., Schweiger C., and Otter M., “Modeling and Simulating the Efficiency of Gearboxes and Planetary Gearboxes,” 2nd International Modelica Conference, Proceedings, pp. 257-266.
|
2016-05-05 02:58:31
|
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|
https://codereview.stackexchange.com/questions/91728/can-i-buff-up-your-file/91735
|
# Can I buff up your file?
Here I have a method for reading the contents of a file into a buffer and returning whether or not it is successful.
Here is what I would like reviewed:
• Speed: Am I reading in the file as fast as possible?
• Bugs: Are there cases where my code could fail or give unexpected behavior?
• Syntax/Styling: How does my code look? How could I make it look better? Anything I'm doing wrong syntax-wise?
int getFileContents(const char *file, void **contents, size_t *size)
{
int fd = open(file, O_RDONLY);
if (fd < 0) return -1;
off_t total = lseek(fd, 0, SEEK_END);
if (total < 0) return -1;
lseek(fd, 0, SEEK_SET);
ssize_t n, rest = total, readb = 0;
unsigned char buf[BUF_SIZE];
unsigned char *result = NULL;
// Read the whole file into memory
while (rest > 0) {
if (n < 0) {
close(fd);
free(result);
return -1;
}
unsigned char *tmp = (unsigned char*) realloc(result, readb + n);
if (!tmp) {
close(fd);
free(result);
return -1;
}
result = tmp;
rest -= n;
}
close(fd);
*contents = result;
*size = total;
return 0;
}
### 1. Bugs
1. If the open succeeds but the lseek fails (as it might if the file is a named pipe), the function omits to close the file descriptor, thus leaking it.
2. If read reaches the end of the file (as it might if the file was truncated after the lseek), then it returns 0. This will cause the function to go into an infinite loop.
3. There's no check on the result of the second call to lseek. If this call fails, then the function will go into the infinite loop described above.
### 2. Review
1. There's no specification. What does this function do? How do I call it? What does it return?
2. This is a worst-case $\Theta(n^2)$ algorithm, because realloc may have to copy the result each time it grows, and you grow the buffer by at most BUF_SIZE bytes each time you call realloc. It's usual in this kind of situation to grow the result exponentially, by multiplying the result size by some constant on each realloc call.
3. Even ignoring the copying due to realloc, each byte read from the file is copied again using memcpy. It would be better to realloc the result first, and then read directly into the result.
4. You go to the trouble of finding the length of the file, so why not read it all in one go?
result = malloc(total);
if (!result)
/* handle error */
if (n != total)
/* handle error */
5. Consider using fstat instead of lseek to determine the size of the file.
6. It's not a good idea to put multiple statements on the same line, like this:
if (fd < 0) return -1;
That's because in most debuggers you won't be able to set a breakpoint on the return statement.
7. There's repetition in the handling of the four failure cases. This makes the function difficult to modify (because you might fail to adjust one or more of the cases). The bug in §1.1 above might have been caused by this problem.
8. For reading the entire contents of a file into memory, consider using mmap.
mmap has advantages over read. (i) There's no need to allocate a buffer: the kernel maps the file directly into the process's virtual memory. (ii) mmap operates lazily: it maps the file into memory but does not actually copy any part of it until that page is touched, so programs that randomly access the file don't have to wait for the whole file to load.
mmap also has disadvantages. (i) mmap only operates on ordinary files (not pipes, sockets, or other kinds of file descriptor). (ii) Mapping lots of files creates lots of entries in the process's virtual memory table, and on some operating systems (notably OS X) this can lead to poor memory performance.
### 3. Revised code
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
/* Map the contents of file into memory: if successful, update
* *contents to point to the file contents, update *size to be the
* size of the file, and return 0. Otherwise, return -1.
*/
int getFileContents(const char *file, void **contents, size_t *size)
{
int fd = open(file, O_RDONLY);
if (fd < 0)
goto fail_open;
struct stat st;
if (fstat(fd, &st) < 0)
goto fail_fstat;
void *result = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (result == MAP_FAILED)
goto fail_mmap;
*contents = result;
*size = st.st_size;
close(fd);
return 0;
fail_mmap:
fail_fstat:
close(fd);
fail_open:
return -1;
}
1. I would return a different number for every error, to help the user of the function to identify the problem and try to recover.
In this context (Unix systems programming), it's conventional for a function to return a single distinguished value (typically −1) to indicate an error, with the cause of the error being stored in errno. See for example the POSIX specification of open:
Upon successful completion, these functions shall open the file and return a non-negative integer representing the lowest numbered unused file descriptor. Otherwise, these functions shall return -1 and set errno to indicate the error.
It makes sense to stick to the Unix convention, so that the caller can apply the same kind of error handling to getFileContents as they do to other system interfaces.
2. Every error between open and close need the call to close, and leaving it inline is easier than check the list of label is correct, IMHO. It is true that you are writing some more lines.
If you write out the error-handling code inline, then your functions have length that's quadratic in the number of error cases! This is disastrous for readability and maintainability. It is all too easy to forget one of the cases, as in the bug described in §1.1 above.
An alternative to goto is to use nested if statements. In this case the code would become:
int fd = open(file, O_RDONLY);
if (fd >= 0) {
struct stat st;
if (fstat(fd, &st) == 0) {
void *result = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (result != MAP_FAILED) {
*contents = result;
*size = st.st_size;
close(fd);
return 0;
}
}
close(fd);
}
return -1;
but this quickly becomes hard to read because of the indentation.
• Excellent review, nice work! – Mast May 25 '15 at 19:18
• instead of goto i would return a different number for every error, to help the user of teh function to identify the problem and try to recover. Every error between "open" and "close" need the call to close(), and leaving it inline is easier than check the list of label is correct, IMHO. It is true that you are writing some more line – Lesto May 26 '15 at 0:48
• @lesto: Replies in §4. – Gareth Rees May 26 '15 at 9:44
• @GarethRees now you have my upvote. Thank your for clarifications – Lesto May 26 '15 at 10:05
Since you get the total size of the file when you do total = lseek(fd, 0, SEEK_END), I don't see the point in reading in BUF_SIZE chunks. You could read the whole thing in one go, and greatly simplify your code, not to mention the reduced memory copies. Something like this:
int getFileContents(const char *file, void **contents, size_t *size)
{
int fd = open(file, O_RDONLY);
if (fd < 0) return -1;
off_t total = lseek(fd, 0, SEEK_END);
if (total < 0) return -1;
lseek(fd, 0, SEEK_SET);
ssize_t n;
unsigned char *result = (unsigned char*) malloc(total);
if (n < 0) {
close(fd);
free(result);
return -1;
}
close(fd);
*contents = result;
*size = total;
return 0;
}
Speed: Am I reading in the file as fast as possible?
I think my suggestion is faster, thanks mainly to the reduced allocations and memory copies.
Bugs: Are there cases where my code could fail or give unexpected behavior?
I cannot see.
Syntax/Styling: How does my code look? What about it could make it look better? Anything I'm doing wrong syntax wise?
The comment // Open file for reading right before the open call is really unnecessary. Other than that, it seems fine.
• read can read less than what you requested without it being an error. Your version doesn't account for that, potentially returning a partially-filled buffer to the caller. – Mat May 26 '15 at 7:07
• Yeah, but that's not a bug I introduced, it was already there in OP's code. Gareth treated it already, and better, so I won't fix that now. – janos May 31 '15 at 16:52
|
2021-06-17 08:59:31
|
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|
https://derive-it.com/2021/01/01/the-pythagorean-theorem-and-the-unit-circle/
|
This following diagram shows that $\displaystyle \sin^2 \theta + \cos^2 \theta = 1$, given $\displaystyle \cos \theta \equiv \frac{adj}{hyp}$ and $\displaystyle \sin \theta \equiv \frac{opp}{hyp}$ and the Pythagorean theorem. Here, $opp$, $hyp$, and $adj$ are variables for lengths. The values corresponding to these lengths are positive numbers or zero.
|
2023-02-09 06:26:35
|
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|
http://threadposts.org/question/546478/W10-Update-not-completed-No-Mouse.html
|
Tech Problem Aggregator
W10 Update not completed - No Mouse
Q: W10 Update not completed - No Mouse
After the automatic update this morning my desktop shows normal - BUT NO MOUSE. A warning pops out in the lower right corner that says something about the update did not complete - Click for details, But I can't click on anything!!!
A: W10 Update not completed - No Mouse
Can you use the cursor arrows to navigate there?
2 more replies
I'll give some background.
I have a tri-boot setup. Windows 8 one ssd, windows 7 pro on a second ssd and ubuntu 13.04 on a partition on a 2 gig raid 1. The boot partition is on the windows 7 ssd. All drives are on the same Intel controller. Prior to the 8.1 attempt it worked. I'd boot the w7 ssd and a black win7 style boot screen would appear with the 3 OS choices. I'd been using win 8 as primary since it's release with no real issues.
I updated through the store early today and the process had a hitch after the first reboot but I rebooted and it completed the install. Windows 8.1 started and walked me though an initial setup. Once in, all looked pretty much unchanged. The only issued was it asked me to reinstall some XLan software.
I rebooted to check my other OS's and the problems began. I boot up, it loaded the blue win8 boot screen with all 3 OS present when I attempted to boot ubuntu it went to a black screen with no possible input. Hard rebooting brought up the grub bootloader (not win8 bootscreen) and I was able to enter ubuntu. Same thing happened with win 7 pro. I soft rebooted and the win 8 bootscreen appeared. Choosing win 7 took me to a hung black screen - hard reboot directly started up win 7. Restarting to win 8 bootscreen again and choosing win8.1 took me to another black screen - Hard reboot from there started up a win 8 repair process.
This is always the case with each of the 3 OS's. I have found that I can get into win8 if I enter through safe mode ... Read more
A:8.1 update completed but problematic
I have the exact same problem. I even had the XLan error you described. Once I restarted the computer, it always go to a black screen. I do not have multiple OS's to boot into, but the black screen always comes up after the little blue windows 8 loading screen.
If you get your issue solved, please report back.
Update:
When I tried your suggestion of enabling Debugging, it loaded up. However, 1-2 minutes later it would freeze and I would have to push the reset button on the machine. In Safe Mode, I didn't have any of the freezing, but when I tried to uninstall Norton Internet Security, it would freeze. After a restart, I downloaded the Norton Removal Tool, and removed Norton. At this point, starting Windows 8.1 with Debugging allows me to stay freeze-free. However, trying to start up without Debugging gives me the same black screen.
Another thing to note is that when I have all non-Microsoft services stopped, I still get the black screen upon bootup. I'm not quite sure what Debugging mode does in terms of bootup, but its definitely a workaround for now. I used msconfig.exe to keep debugging turned on for now.
Again, if someone figures out the fix, report back.
2 more replies
When updating to Windows 10 Anniversery Update (1607) everything goes fine till the first restart of the computer.Nothing happens even if you wait for about 8 hours. The screen is blank and the keyboard does not respond. After having turned of the computer and started it again you get the information: "Restore the earlier version of Windows..." (Windows10 for home use).
More replies
Just wanted to add my story, similar to above. Product# F3F15UA#ABA, 10" Pavilion notebook. Win 10 Anniversary Edition update will not install. Machine gets to 32% and then locks up completely; grey blank screen. Have to unplug and remove battery to shut down. After powering back, automaticaly recovered to previous version of Win 10 (1511). Machine now almost unusable since it spends all day re-downloading the update files and then doing an automatic update reboot every evening. This has happened 4 times already; now keeping it in airplane mode. Was on MS Assure service for hours. 2nd tier guy said to just wait for MS to come out with a revised version of the update. Tried installing MS registry update fix (MSI) issued 10/5, but did not fix the problem. I have a completely clean machine, all drivers up-to-date, nothing installed except Office 365 and 7-Zip. Installed Win 10 1511 as a complete replacement (OS and all apps) a few months ago and performance improved tremendously. Except for this update problem, after the OS replacement PC works very well (for a slow, under-memory PC). I mainly use it to take to meetings to give PowerPoint presentations, for which it works just fine. I never do email with it or download apps. Above reply suggests updating from a USB after a image backup. Can try that to see if I get a better result, but wonder if it would be better to skip "update" and, i... Read more
More replies
I got the message to update my BIOS. It was dated in May 2016. The latest on the website was August (8/11/2016). I updated it and the computer shows the new version but still says it needs to be updated and tried everytime on a reboot.
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I tried to update to 1.7 and it failed. We had to run a mongo change regarding the certificate. When that was completed the install was fine, but we started getting an invalid cert on the web interface. I finally dug into it and saw that
the ata gateways were no longer talking as well.
I updated the cert so i have that cleared up but the gateways wont connect. I updated them manually by downloading the installer and the install went fine but they still wont connect. I decided to look at the cert thumbprint of the package /
json file and it is below.
What would i need to get these to connect again?
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Hey all. I had a recent round of Windows updates for Vista and one of them apparently killed my mouse. I have a generic Logitech wireless mouse and keyboard. The keyboard continued to work just fine, but not the mouse. Vista recognizes the mouse as a "HID-compliant mouse". My guess is that something happens to the drivers after one of the updates.
Anyway, I used System Restore to return my computer to the period just before installing the updates and the mouse worked again.
Here is a list of the 11 updates--I presume one of them is the cause:
1) Cumulative Security Update for Internet Explorer 7 in Windows Vista (KB947864)
2) Security Update for ActiveX Killbits for Windows Vista (KB948881)
3) Security Update for Windows Vista (KB941693)
4) Security Update for Windows Vista (KB945553)
5) Security Update for Windows Vista (KB948590)
6) Update for Windows Vista (KB938371)
7) Windows Malicious Software Removal Tool - April 2008 (KB890830)
8) Update for Windows Mail Junk E-mail Filter [April 2008] (KB905866)
9) Security Update for Microsoft Office Visio 2007 (KB947590)
10) Update for Microsoft Office Outlook 2007 Junk Email Filter (KB949037)
11) Update for the 2007 Microsoft Office System (KB946691)
Obviously, my next step would be to install each update individually and try to identify the potential cause, but before doing that I thought I'd come here and see if anyone has heard about this sort of thing happening before and how to work around i... Read more
A:Recent windows update kill mouse drivers and/or mouse operation
Bump to the top.
19 more replies
After installing updates from Windows7 & Windows Live, the mouse & PC freeze. Cant even use Ctrl-Alt-Delete as they are frozen. Win Live has also wiped all my contacts. I am having to stop & restart 7 times a day......absolute pain!
I am writting this from a notebook using the same wireless router, so it is only the PC thats afected.
I am also having trouble with AVG as this has turned itself off and wont restart. Have tried un-installing but wont un-install properly so I cant re-install. Nightmare.
Can anyone help please?
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hi all, another question after these update i notice and after restart the mouse not work good! is very unstable and it is tiresome to work...
have you a solution please? thanks
A:mouse and update
Yep Salvo mate run a system restore back to before those updates and then pull them up again and then install each one on it's own.
I persnally choose to have updates advised to me first before I download them but the choice is yours on how you set the update service. (see pic)
3 more replies
Hi. I have been having trouble with my mouse after getting a windows update. After updating, my mouse doesn't work. I can use a flash drive on that same usb slot, but I can't use the mouse. Windows even knows that the mouse is there. I can get it to work if I use a system restore from before the update but every time my computer updates, the mouse won't work again. It is a Targus retractable usb optical mouse. Any help would be greatly appreciated.
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Hello all,
I currently have Win7 64-bit Ultimate, I did the SP1 update last night and all was well, until it was finished, upon logging in after the last reboot my Logitech MX mouse no longer responded to clicks or movement. I tried navigating with the keyboard and downloaded the setpoint drivers for the mouse and installed, but didn't do anything, I tried different USB ports, nothing. Keyboard works though and it is USB. I tried going to the restore point, but once I got there it said there was not one available, even though before the SP1 install it said it did one...
So I have not tried another mouse option yet due to, 1, I was up til 2am working on the issue, and 2, I did not have another mouse available until I could borrow one from work. Weird thing really, mouse was working perfectly before the update.
Wondering if anyone else has heard of this issue?
A:Mouse not working after SP1 update
I've never heard of that happening. I suggest you go to the Logitech website and create an account on their support forums, and post your question there. While you might get some responses here, you definitely will get more responses over there. I also suggest opening a support ticket with them.
4 more replies
I recently downloaded and installed a security update for Vista and after I rebooted, my wireless mouse stopped working. My keyboard still works, though. I went through normal steps: replaced batteries, tried other USB ports, tried wired mouse in both USB and PS/2 ports, uninstalled drivers and reinstalled, did a system restore. I tried doing system restore to the day before the update and it failed twice, so I pulled it back to 3 days before and it said it was successful, but my mouse still won't work. Any time I plug a mouse in and look in the device manager, the driver under the mouse has a yellow triagle with a '!' inside it. No matter what I do, that always shows up when I plug something in. Is there anything else I can do short of reinstalling Windows/reformatting?
Thanks!
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Quote:
Microsoft - Other hardware - Microsoft Hardware USB Mouse
You may need to restart your computer for this update to take effect.
Update type: Optional
Microsoft Other hardware software update released in June, 2010
Winqual Help
Help and Support:
Select a Product Solution Center
Can anyone explain what this is? Over the years I've come to expect usb drivers from your chipset drivers (or is it a device?). I'll admit, I've never heard of a USB mouse driver . This updated popped up recently and I can't seem to get any information as to why I'm being asked to download this? Can anyone help?
A:Update: MS Hardware USB Mouse. What is this?
its just an optional update.. if everything is working fine i'd just ignore it
5 more replies
My computer automatically installed uupdates last night 10/17/08
When I got up this morning, my wireless mouse did not work. I tried new batteries and all USB ports. Then I plugged in another mouse and it too did not work.
I found another thread that mentioned update KB938371 causing a similar problem, but that uppdate was done in September for my new laptop with no trouble.
In device manager, my USB ports have an exclamation mark. I checked for drivers, but my computer assures me that my updates are installed with the latest software. I do not have the option of rolling back the driver.
The USB ports supply power to my speakers and my cooling pad. Also, both of my flash drives worked.
Another hurdle - I am not real sharp where computers are concerned.
A:After Update Mouse Won't Work
Hi, this issue can be caused by USB driver corruption. I suggest you try the following two suggestions and see the result:
Suggestion 1: Remove all the USB device drivers
===========================
1. Disconnect all USB devices.
2. Click Start, type CMD in Start Search and press Enter.
3. In the DOS Prompt window, copy and paste the following command and press Enter at the end of each line:
set devmgr_show_nonpresent_devices=1
cd %SystemRoot%\system32
start devmgmt.msc
4. In the opened window, select View and then Show hidden devices.
5. Expand the "Universal Serial Bus controllers" branch, right-click and click Uninstall on everything related to the problematic device or "Unknown Device".
6. Search other branches and delete everything related to problematic device or "Unknown Device".
7. Plug the problematic device to the USB port and install the latest drivers again.
8. Test this issue. If the suggestion 1 cannot resolve the problem, please go to suggestion 2.
Suggestion 2: Reinstall USB Controller
===========================
First, please disconnect all USB devices. Then, go through the following steps:
1. Click Start.
2. Type devmgmt.msc in Start Search and press Enter.
3. In Device Manger, double click to expand "Universal Serial Bus Controllers".
4. In the expanded menu, move down to the first item, right click and select Uninstall and click OK.
5. Repeat the step 3 to uninstal... Read more
9 more replies
since a recent windows 7 update when i power up my pc the keyboard and mouse are undetected so i cant get past the password screen. i thought a system restore is the solution but i cant get into bios either as i need to select that with the keyboard.
keyboard and mouse are usb.
ive tried all usb ports.
what do i do ???
all ideas, help appreciated as im totally confused about how to tackle this
ive been told by one person to try a keyboard with ps2 connection, i dont know anybody with 1
there must be another route i can take?
i dont even know what update has done this?
A:no keyboard or mouse detected after win 7 update
Reset your BIOS and then try restarting the computer. If USB support is a default value then it should boot, if not then you will need a PS/2 keyboard. What puzzles me is that no Windows Update can alter your settings in the machines BIOS - so perhaps it's just a question that your USB ports aren't working...
3 more replies
I did a clean re-install of Windows 8.1 as I had numerous problems due to malware, etc with 8.1.
After installing Windows (no problem during installation), I started to install my software, and often had to restart my PC as required by some programs.
After one of these restarts, the mouse and keyboard did not work. I replaced the batteries (it is a wireless Microsoft mouse (MS Wireless Mouse 1000; Model 1454) and keyboard (MS Wireless Keyboard 800;Model 1455))-this (batteries) in the past have often been the problem. No luck.
I then tried another wired mouse and keyboard, which also did not work. I took it to my technician. He used his own mouse and keyboard, which worked, but at home the same sage with both sets, continued.
I searched the internet, but mostly the answers were aimed as if you have a working mouse and keyboard-click on this; open command prompt; etc.
I made no progress. I suspected that the drivers needed to be updated. I spent hours researching the subject and tried various options.
I then decided to re-install Windows 8.1. The Microsoft keyboard and mouse still did not work after this installation. I took it to the technician again, his mouse and keyboard again worked on my PC. I bought a wired mouse and keyboard. After that the system was working very well. I installed all my programs, editing videos, etc.
Two nights ago there was a Windows Update-must have been a big update as it took quite a while to install.
When I next tried to work on the PC, the mous... Read more
A:Mouse not working after installing 8.1, again after update
Any HID compatible device should work without any special drivers. Have you tried Safe Mode to see if it works?
5 more replies
after installing the windows updates this week on my winxp sp3 laptop i discovered that with plugging in the usb mouse the system crashes and goes into a continual reboot, it does flash a bsod when crashing but isn't up long enough to read one word of it. when i unplug the mouse the laptop boots up fine but as soon as i plug the mouse in it crashes. I'm happy that it appears that plugging in a flash drive doesn't cause it to crash. Can anyone recommend a route for me to take to hopefully correct this? I tried different mice and each crashes the system with the repeated reboot. thanks for any help.
A:mouse crash after windows update
Welcome back to TSF
Lets make sure its the update that is causing this. Recently Microsoft has urgently pushed out a remote-code exploit that could spread rapidly like the 2003 MSBlaster worm. Read below:
Quote:
A remote-code exploit that could spread rapidly like the 2003 MSBlaster worm is putting all versions of Windows at risk.
Rare out-of-cycle patch emphasizes the risk
With little warning, Microsoft released yesterday an unscheduled or "out-of-cycle" patch for a highly critical vulnerability that affects all versions of Windows. Security bulletin MS08-067 (patch 958644) was posted to warn of a remote-code attack that could spread wildly across the Internet.
Microsoft says it found evidence two weeks ago of an RPC (remote procedure call) attack that can potentially infect Windows machines across the Net with no user action required.
Windows Server 2003, 2000, and XP (even with Service Pack 2 or 3 installed) are particularly vulnerable. Vista and Server 2008 gain some protection via User Account Control, data-execution protection, and other safeguards, as explained in an article by Dan Goodin in the Register.
While firewalls are a first line of defense against this attack, don't think you're secure just because you have a firewall. Malware and viruses use many different techniques to wiggle their way into our systems.
For example, my office's networks are protected by firewalls on the outside, but inside the network, ... Read more
2 more replies
Im a novice btw.
System specs if needed:
i7-3770k
Asus Sabertooth z77
16 gb corsair vengeance
850 watt corsair power supply
gtx 670
Its a few problems im running into. No ps2 port and the cmos battery is covered by a black shield. No other computer to use btw. Was wondering if it was any other way to fix the problem. I put a picture of the motherboard in the attachments. Its a bios button on the back of the motherboard but ive tried holding it down while i booted the machine and it still didnt work. It also said to use the delete key with the bios button but i have no keyboard or mouse.
Would a wired usb keyboard/mouse work? Im guessing no since i think im having driver issues...
Any help would be appreciated...
A:After windows update. No keyboard or mouse.
I'd try replacing the CMOS battery. IME, a failing battery can cause unusual system hardware configuration problems.
If you go that route...please remember to reset date/time data in the BIOS after replacing with a new battery.
Louis
1 more replies
Hi all since updating windows to windows 8.1.1 my alienware tact x mouse keep lagging on me from time to time, i checked in device manager and everything says its working properly, but it will lag out on me for a few seconds and then work just fine. What could be doing this i did not have any issue before the update.
A:Windows 8.1 update and mouse issue ???
Sounds driver related, do you have the most current driver installed? I had the same thing for my mouse (Logitech 500), I was using an old driver and never updated as it worked fine. After the update it didn't, installed the latest and problem solved.
3 more replies
is there any latest driver for logitech serial (3 buttons) mouse for xp-pro
model #: M-MC13-DB9F
xp was able to install the native driver and all 3 buttons work and so does the movement, but the pointer tend to fly off randomly whenever i move the mouse
any links for latest driver
A:logitech serial mouse update
check here
http://www.softlookup.com/driveauthor.asp?id=295
4 more replies
Hi all
I have found this site after googling for any forum where i might be able to get some advice on the following problem. I have included it in this forum as i am unsure whether it could be related to a virus potentially, despite visiting no site with any threat.
I recently received my laptop back from a supplier (yesterday) (Samsung) who restored new hard drive etc, and it appeared to work fine up until this morning.
However, the windows updates (i use windows 7) which required me to restart the computer has since caused me a huge and incredibly irritating issue.
Once the desktop loads up again after the updates, the mouse cursor is flying around the screen uncontrollably, i cannot seem to control it myself, and it is constantly "right clicking" , inevitably clicking aimlessly on other things that load up and cause a lot more clogging up making the laptop out of control.
I am in no way able to "tame" the cursor and the laptop is totally unusable due to this cursor problem. I have now had to reboot the laptop twice and do a full system restore just to get the mouse/cursor working again, and know that next time it wants to update and restart windows 7, the problem will just return. Control alt/delete does not work due to mouse not being able to be used, not even the tab key can select on anything.
Can anyone advise what the diagnosis is here, is it a windows 7 compatibility issue, or otherwise? Im hoping i can get this sorted out because i nee... Read more
A:Windows 7 Mouse Issue after update HELP!
Bump
1 more replies
is there any latest driver for logitech serial (3 buttons) mouse for xp-pro
model #: M-MC13-DB9F
xp was able to install the native driver and all 3 buttons work and so does the movement, but the pointer tend to fly off randomly whenever i move the mouse
any links for latest driver
A:logitech serial mouse update
Time to clean the mouse with alcohol and some Q-Tips (if you don't want to hear about PS2 mouse).
2 more replies
I ran a Vista update yesterday, and now my mouse is frozen.
I tried different mouses on different ports which also failed.
I tried doing a system restore which also failed.
Does anyone have any solutions? Any help would be
most appreciated.
A:Mouse froze after Vista update
Mine did that too i had too reinstall. But my mouse and keyboard didnt work
3 more replies
hey im having problems with installing windows xp SP3 i boot to cd do the whole installation thing for step 1 and then it restarts and then im waiting for the continuation of the installation but it doesnt happen it boots to cd again without me pushing anything
A:Installation not completed
6 more replies
I did not get any replies so will try this again with updated info. Downloaded Microsoft Pocket PC 2002 October 2002 Update(EUU3) to computer but when tried to sync it to handheld got message: "Synchronization Cannot be Completed Successfully" and have not been able to sync since then. Same message and then disconnects. Have reinstalled Activesync twice..even going to older version. Have done disc cleanup and defrag. Have deleted recent programs including the EUU3. Also soft resert on handheld although problem developed in computer before could sync to there. There is no problem in connection of handheld with computer..just will not sync. Any help much appreciated as cannot download or sync any material to handheld(iPAQ3835) at all.
Thanks!!! John
A:Synchronization Cannot be Completed..
6 more replies
Model HP 15 notebook PCProduct no. J8B82PA#ACJRam 4gbHard disk 1tb HDDProcessor Intel core i3 1.70 GHzWin does 8.1 64 bit
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I accidentally infected my computer with security toolbar 7.1. I have done the 5 steps and i did not get a log from that first scan but here is the log it gave me on the last one.
Deckard's System Scanner v20071014.68
Run by Alan Hickman on 2007-10-21 13:33:39
Computer is in Normal Mode.
--------------------------------------------------------------------------------
-- System Restore --------------------------------------------------------------
Successfully created a Deckard's System Scanner Restore Point.
-- Last 5 Restore Point(s) --
98: 2007-10-21 18:33:54 UTC - RP572 - Deckard's System Scanner Restore Point
97: 2007-10-21 10:02:26 UTC - RP571 - Software Distribution Service 3.0
96: 2007-10-21 09:56:58 UTC - RP570 - Installed Windows Defender
95: 2007-10-21 09:24:44 UTC - RP569 - Restore Operation
94: 2007-10-20 09:03:00 UTC - RP568 - System Checkpoint
-- First Restore Point --
1: 2007-08-01 05:41:11 UTC - RP475 - System Checkpoint
Backed up registry hives.
Performed disk cleanup.
Total Physical Memory: 504 MiB (512 MiB recommended).
-- HijackThis Clone ------------------------------------------------------------
Emulating logfile of Trend Micro HijackThis v2.0.2
Scan saved at 2007-10-21 13:35:50
Platform: Windows XP Service Pack 2 (5.01.2600)
MSIE: Internet Explorer (7.00.6000.16544)
Boot mode: Normal
Running processes:
C:\WINDOWS\system32\smss.exe
C:\WINDOWS\system32\winlogon.exe
A:Completed five steps...here is the log.
Bump!
3 more replies
Hi,
Having successfully performed a 3 hour chkdsk by means of a downloaded microsoft program which did this automatically, the screen is left hanging and there is no option available to exit from it. I tried switching off and then on again but this just puts me back to the start of the chdsk routine which then completes again. So I'm stuck in a loop from which I can't escape !! What do you recommend ?
A:After chkdsk has completed
Hello ,
here is a shot in the dark
turn your system on & then back off
then un plug your system
them push your power button as if you wanted to start it and hold it for a count of 10
this will clear the compleat system of power and maybe reset way your system starts / you may want to reset the bios also by crossing the bios jumpers or just pulling the litheum battery from your mother board for at least 3 minutes
then try your system
you may be looking at wipeing the driver & reinstalling
have you tried to get into the recovery console useing the Windows XP cd ?
3 more replies
Finally got my gaming rig built and in perfect working order. Took me a while figure out how to put my two HDD into raid 0. One of the tech support guys at EVGA helped me out and said that HDDs have a hard time going into raid array if they have never been used, which was the case. I just installed some stuff on my two HDDs and reformatted the partition and BOOM it stopped giving me errors, LOL. Anywho here is the finished build:
Cooler Master Cosmos 1000 Silent Gaming Tower
EVGA 750i FTW Motherboard
Intel E8400 Wolfdale Processor
Xigmatek HDT-D1284 120mm Rifle CPU Cooler
MX-2 Thermal Compound
2x2GB OCZ DDR2 1066 5-5-5 18
2xEVGA 8800GTS in SLI
3xSeagate 7200.11 (2 in Raid 0, 1 backup)
Corsair 750TX Power Supply
Samsung DVD-RW w/ Lightscribe SATA
Liteon DVD-RW IDE
4 Scythe KAZE 120mm case fans (1 intake, 3 exhaust)
1 Stock Exaust Fan on HDDs
When I looked at the Case for the first time I couldn't believe how big it was, plenty of room to work in. The Scythe fans sound like a tornado when I first turn on the computer but it gets quite once the bios and PSU start regulating them and you can't notice it when playing games or listening to music. I bought a generic filter for the intake fan and realized that it wasn't needed because the case already comes with filters that you just slide off and wash.
This was my first build ever and I must say I'm quite pleased with the results. The bios defaulted the memory at 800mhz 1.9v so I bump... Read more
A:First Gaming Rig Completed
Cool. Looks like a good build.
7 more replies
Logfile of HijackThis v1.99.0
Scan saved at 16:26:28, on 08/01/2005
Platform: Windows XP SP1 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\PROGRA~1\McAfee.com\PERSON~1\MPFSERVICE.exe
C:\WINDOWS\System32\ScsiAccess.EXE
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Trend Micro\PC-cillin 2002\Tmntsrv.exe
C:\Program Files\Trend Micro\PC-cillin 2002\PCCPFW.exe
C:\Program Files\Thomson\SpeedTouch USB\Dragdiag.exe
C:\Program Files\Common Files\Real\Update_OB\realsched.exe
C:\PROGRA~1\McAfee.com\PERSON~1\MpfTray.exe
C:\PROGRA~1\mcafee.com\agent\mcagent.exe
C:\Program Files\Trend Micro\PC-cillin 2002\pccguide.exe
C:\Program Files\Trend Micro\PC-cillin 2002\PCCClient.exe
C:\Program Files\Trend Micro\PC-cillin 2002\Pop3trap.exe
C:\WINDOWS\System32\ctfmon.exe
C:\PROGRA~1\McAfee.com\PERSON~1\MpfAgent.exe
C:\Program Files\Kodak\Kodak EasyShare software\bin\EasyShare.exe
C:\Program Files\Ulead Systems\Ulead Photo Express 2 SE\CalCheck.exe
C:\WINDOWS\System32\wuauclt.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Documents and Settings\David.DAVID-91YJAB3H3\Desktop\HijackThis.exe
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.wanadoo.co.uk/
R1 - HKCU\Software\Micros... Read more
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Avast seems to find a new malware every 20 min. I could not complete a panda activescan because the update would stall and hang at 19 %
Deckard's System Scanner v20071014.68
Run by Owner on 2008-05-30 21:04:04
Computer is in Normal Mode.
--------------------------------------------------------------------------------
-- System Restore --------------------------------------------------------------
Successfully created a Deckard's System Scanner Restore Point.
-- Last 5 Restore Point(s) --
102: 2008-05-31 01:04:12 UTC - RP583 - Deckard's System Scanner Restore Point
101: 2008-05-30 21:19:31 UTC - RP582 - Restore Operation
100: 2008-05-30 21:12:31 UTC - RP581 - Restore Operation
99: 2008-05-30 21:09:59 UTC - RP580 - Restore Operation
98: 2008-05-30 21:07:03 UTC - RP579 - Restore Operation
-- First Restore Point --
1: 2008-03-02 21:51:33 UTC - RP482 - System Checkpoint
Backed up registry hives.
Performed disk cleanup.
-- HijackThis Clone ------------------------------------------------------------
Emulating logfile of Trend Micro HijackThis v2.0.2
Scan saved at 2008-05-30 2111
Platform: Windows XP Service Pack 3 (5.01.2600)
MSIE: Internet Explorer (7.00.6000.16640)
Boot mode: Normal
Running processes:
C:\WINDOWS\system32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\svchost.exe
A:I have completed the 5 steps!
Hi and welcome to TSF.
My name is Iain and I will be helping you clean your system.
You may wish to Subscribe to this thread (Thread Tools > Subscribe to this thread) so that you are notified when you receive a reply.
Please read these instructions carefully and then print out or copy this page to Notepad in order to assist you when carrying out the fix. You should not have any open browsers or live internet connections when you are following the procedures below.
Note that the fix may take several posts. Please continue to respond to my instructions until I confirm that your logs are clean. Remember that although your symptoms may vanish, this does NOT mean that your system is clean.
If there is anything you don't understand, please ask BEFORE proceeding with the fixes.
Please ensure that you follow the instructions in the order I have them listed.
Do not do anything with this yet!
Reboot
Reboot your system in Safe Mode.Restart the computer. The computer begins processing a set of instructions known as BIOS.
After hearing your computer beep once during startup, but before the Windows icon appears, press F8 (dependent on your system this may be F5 or another key)
Use the arrow key to highlight Safe Mode and press Enter.
SDBot FixRight click the SDFix.zip folder and choose Extract All,
Open the extracted folder and double click RunThis.bat to start the ... Read more
7 more replies
I have a couple of Word 7 files which can't be moved, deleted or renamed. Any attempt results in a message: This action cannot be completed as it is in use by another program. It is not in use by any program I am aware of. When I open the file, it says (Read Only) in the title bar but the properties dialogue boxes are not checked as read only. Of course, I can't save any changes to the file unless I go to 'save as' but that still leaves me with an undeletable/uneditable file. I am using Vista Ultimate. Any help would be greatly appreciated.
Joan
A:This action cannot be completed...
Unless you're particularly interested in the mechanics of why this might be happening, I'd suggest booting to safe mode (press the F8 key early during Windows startup) and moving or deleting the files from there. You probably won't have trouble deleting the files that way.
37 more replies
Deckard's System Scanner v20070804.61
Run by HP_Owner on 2007-08-05 at 16:46:07
Computer is in Normal Mode.
--------------------------------------------------------------------------------
Total Physical Memory: 504 MiB (512 MiB recommended).
-- HijackThis (run as HP_Owner.exe) --------------------------------------------
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 4:37:16 PM, on 8/5/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16473)
Boot mode: Normal
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Common Files\Symantec Shared\ccSvcHst.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Common Files\Symantec Shared\AppCore\AppSvc32.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Common Files\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
C:\Program Files\Symantec\LiveUpdate\ALUSchedulerSvc.exe
C:\Program Files\Common Files\LightScribe\LSSrvc.exe
C:\Program Files\Common Files\Microsoft Shared\VS7DEBUG\MDM.EXE
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\hkcmd.exe
C:\WINDOWS\system32\igfxpers.exe
C:\hp\drivers\hplsbwatcher\lsburnwatcher.exe
C:\Program Files\Common Files\AOL\1128887343\ee\AOLSoftware.exe
C:\Program Files\Common Files\Real\Update_OB\realsched.exe
C:\Program Files\HP\HP Softw... Read more
A:Completed the 5 Steps
Please stay with this thread, and only post here for this problem. Do not start a new thread, otherwise it is too confusing...
Use Post Reply - left bottom corner. Thanks!!
Save it to the Desktop
Double-click combofix.exe to run the program
(Don't click on the window while the program is running, it may cause your system to stall.)
When finished, a log, ComboFix.txt, is produced.
~~~~
19 more replies
Here is my log:
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 9:05:14 PM, on 1/13/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
Boot mode: Safe mode with network support
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Mozilla Firefox\firefox.exe
C:\WINDOWS\system32\drwtsn32.exe
C:\WINDOWS\system32\drwtsn32.exe
C:\WINDOWS\system32\rundll32.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
F3 - REG:win.ini: load=C:\WINDOWS\system32\vtutq.exe
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [ATICCC] "C:\Program Files\ATI Technologies\ATI.ACE\CLIStart.exe"
O4 - HKLM\..\Run... Read more
A:Completed 2/5 steps - please look over this and tell me what to do
Hello
I needed you to go all the way through the steps. We prefer a more comprehensive set of logs to assist in detecting any malware that may be present. As noted in the final step (Step 5) of our sticky topic (Updated!) IMPORTANT - Read This Before Posting A Log, download Deckard's System Scanner (DSS) to your Desktop.
What DSS will do:create a new System Restore point in Windows XP and Vista.
clean your Temporary Files, Downloaded Program Files, and Internet Cache Files, and also empty the Recycle Bin on all drives.
check some important areas of your system and produce a report for your analyst to review.
DSS automatically runs HijackThis for you, but it will also install and place a shortcut to HijackThis on your desktop if you do not already have HijackThis installed.
Note: You must be logged onto an account with administrator privileges.Close all applications and windows.
Double-click on dss.exe to run it, and follow the prompts.
When the scan is complete, two text files will open - main.txt <- this one will be maximized and extra.txt <-this one will be minimized
Copy (Ctrl+A then Ctrl+C) and paste (Ctrl+V) the contents of main.txt in your next reply.
To attach a file to a new post, simplyClick the[Manage Attachments] button under Additional Options > Attach Files on the post composition page, and
copy and paste the following into the "Upload File from your Computer"... Read more
19 more replies
Keep getting the same error over and over, tried many things (inclduing scf /scannow) but to no avail.
Here is the bit from the log:
Code:
1348769 (3424) - winsat\logging.cpp:0815: --- START 2011\10\30 17:15:04 ---
1348769 (3424) - winsat\main.cpp:4301: Command Line = "C:\Windows\system32\winsat.exe" formal -restart clean -cancelevent 8e00fb41-d1d6-4e88-8347-83b99be94b73
1348769 (3424) - winsat\processwinsaterror.cpp:0095: ERROR: tried to read resource strings, unknown exception occured
1348784 (3424) - winsat\main.cpp:4474: > IsFormal=TRUE IsMoobe=FALSE.
1348815 (3424) - winsat\main.cpp:4585: Watch dog system enabled
1348815 (3424) - winsat\main.cpp:4600: Main watch dog timer set to 600.0 seconds
1348878 (3424) - winsat\main.cpp:2505: > DWM not running.
1348878 (3424) - winsat\main.cpp:2470: > EMD service will be restored on exit.
1348893 (3424) - winsat\syspowertools.cpp:0983: > Read the active power scheme as '8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c'
1348893 (3424) - winsat\main.cpp:2793: > power policy saved.
1348909 (3424) - winsat\syspowertools.cpp:1015: > Set the active power scheme to 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c'
1348909 (3424) - winsat\main.cpp:2814: > power policy set to maximum.
1349736 (3424) - winsat\logging.cpp:1763: ERROR: pahse enter/leave imballance
1349736 (3424) - winsat\main.cpp:0948: > IsOfficial=TRUE IsFormal=TRUE IsMoobe=FALSE RanOverTs=FALSE RanOnbatteries=FALSE
1349736 (3424) - winsat\main.cpp:1775: ... Read more
A:WEI test cannot be completed
What language is your OS currently using, and what was originally installed on it? Is one of the two English?
4 more replies
Hi everyone!
Ive just completed my upgrade from an MSI 745 Ulta mobo and ATI Radeon 7000 series 64meg AGP x4 graphics card to an Abit NF7-S mobo and ATI Radeon 9550 AGP x8 256meg graphics card and I gotta say, boy what a difference.
Now I have to save up my pennies to get myself a better processor, I have an AMD Athlon XP Pro 2000 and was wondering what i should replace it with?
There's a fair ammount of choice out there so i was wondering if anyone has any recomendations?
A:Just completed an upgrade
Nice speed jump!
Upgrading always starts with budjet. If you are going to keep your Mb , then simply buy the best (fastest) CPU you can afford at the time.If you are saving pennies you will probably be able to get the quickest cpu your mb can handle.
5 more replies
Desktop machine.
Windows Vista Home Prem. 32b.
The computer shut itself down a few days ago while it was copying for files.
Then, it behaved abnormally after restart.
A back to the factory status recovery was performed, but it did not complete the task.
The last part of the recovery did not run.
The recovery disks, burned right after the purchase of the machine and used before, were used and they ended the same way.
The last part of the recovery did not run.
There are 3 partitions on the HDD.
Partition 0, 20GB. hidden, keeping the recovery OS.
Partition 1. 223GB. partition C.
Partition 2. 220GB. partition D.
Question:
If partition C is formatted, can recovery OS be installed on partition C ?
Thanks.
A:Recovery can not be completed.
What's the brand name and model name and model number of that desktop?
What's the part/product number and/or service tag number and/or serial number on it?
Which country do you live in?
--------------------------------------------------------
3 more replies
Good evening..i have just completed the combofix scan on my Openlabs Neko TSE. Which is my music workstation with a built in computer. Please can you review my log for further advice.? I really appreciate you for this. This workstation is the key to all my productions. I have been freaking out all night. Aloha!
A:completed combofix run
Hello,That request about NOT posting CF logs is primarily to keep people from running the program unsupervised.Please read this topic: http://www.bleepingcomputer.com/forums/t/273628/combofix-usage-questions-help-look-here/ which explains that reasoning further.Please follow the instructions in ==>This Guide<== starting at step 6.Once the proper logs are created, then make a NEW TOPIC and post it ==>HERE<== Since you have run ComboFix, please include the ComboFix log in the new topic.If you cannot produce any of the other logs, then please create the new topic anyway, include the information that you were unable to produce the other logs and why and include the ComboFix log along with a description of your computer issues.Orange Blossom
1 more replies
I bought a Sony Vaio E-Series SVE17812BCXB running Windows 8. After the last major windows update that occurred in Feburary '13, the keyboard/mouse stop responding once the fully loaded splash screen is presented (With the time and date, ect).
I know the keyboard and mouse are fully functioning as I can use them when I access the boot menu before the OS is loaded. Also, only the keyboard 'functions' work when the OS is loaded, such as adjusting the brightness of the monitor (fn+F5) and such, but nothing else.
I try to do a system restore and it fails on all available restore points. I try to do a manual repair using a bootable USB drive, and it just loads windows like normal. I'm at a loss on how to get this fixed and as of right now, I purchased an \$800 paper-weight.
Has this occurred for anyone else?
A:No Keyboard/Mouse Response after Windows 8 Update
This does not help, but apparently you are not alone. I would complain to Microsoft and try to get support from them.
Windows 8 Keyboard and mouse not working
This thread showed others with different manufacturers with same issues.
Doc
3 more replies
Windows 10 Anniversary Update, with version 1607, installed satisfactorily EXCEPT Logitech gaming keyboard & mouse will not work in the game. Both worked fine in prior version. Problem only occurs in this game. Any help greatly appreciated.
Thanks,
yodaplumber
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Hi,
I have recently updated my mac 10.9.5 to Yosemite. After installing the update, my keyboard and mouse (usb), have stopped working.
I have tried rebooting, changing ports and even plugged in an old style wired six pin, but no luck...
I have tried PRAM but the computer only beeps once and doesn't reset itself like it should do.
In the BIOS/set up screen the mouse and keyboard work fine, but not in safe or regular mode.
As a result I can't log in to check what's going on or use time machine to restore to a different point.
Could anyone help?...
Cathey
A:Keyboard and mouse not working after software update
Is your keyboard and mouse compatible with Yosemite ?
Check from the manufacturer's website.
Do they use any driver ?
If yes uninstall the old one and upgrade to the new from the manufacturer's website.
Check if the cables are okay.
2 more replies
Hi Experts,
This is a very strange issue on my domain environment two lenovo laptop's e540 goes stuck no pointer and keyboard is working but when i uninstall some latest update and restart it works fine.
here are two update which are recently install and make problem and after uninstall issue has been fixed.
1) KB3194798
2) KB3197356
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My mouse was working fine but after the 12/5 updates were installed I have two issues.
1) I have to keep re-connecting my Bluetooth mouse. I will pair it and it will work for 5 minutes to an hour and then just quit working. It still shows paired, but will not work.
2) every time I reboot, I get an error handle message with only the option to click okay. I am wondering id the two are connected.
For the mouse I have done the following:
1) Updated all drivers
2) Uninstalled and reinstalled my Bluetooth hardware
3) Unchecked the power management box
4) bought a new mouse exact safe results
5) made sure all windows updates are installed
I only have one USB port, so I really want to use a Bluetooth mouse.
Ant assistance would be greatly appreciated. How do I check why I am getting the error handle message?
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Anyone else having issues after their Windows 10 anniversary update that the mouse scroll is insane?.
already set it to move only 1 line, but doesn't seem to fix it... Kinda lost here
All my programs 1 little scroll, makes things fly over the screen.
Didn't have that problem before the update.
A:Windows 10 Anniversary update Mouse issue
Touch pad or real mouse ?
Scroll can be adjusted thru Start > Devices > Mouse & touchpad.
6 more replies
Please forgive me for not searching properly to see if anyone else has had a simular problem, but I'm not very good at using my keyboard for navigating. It's taking me ages just to get this far.
My Mouse pointer arrow disappeared after an update. I noticed the update icon when i went to shut the computer down. After it turned off, I turned it back on again, and no mouse pointer. I then tried to look on the windows vista help and that's missing too I tried unintalling the updates but that didnt help. I can see the devices in the system list thing, and thats about the extent of my knowledge. Both the keyboard and mouse are wireless, the keyboard is fine, and the mouse operates the light on the reciever. Its just got no pointer to move.
I hope that makes sence. If it doesnt, I blame it using up the last of my brain power trying to do things without a mouse.
Nicky
A:Mouse Pointer Lost after Auto Update
Same thing happened to me but I was able to fix mine this way:
Windows Key to get up the Start menu and use the arrow keys to select 'Control Panel' and enter to open
Use the tab key to select 'System Maintenance' and enter
Tab down to 'Device Manager' and enter. Tab to select 'Continue' then enter
Press Tab and then arrow down till you highlight to the Unknown Device with an !
Enter to select. Use the tab and arrow keys to select 'Update Driver' and press enter.
Reboot and you should hopefully have your mouse pointer back too.
2 more replies
Possibly bug in Microsoft Security Essentials in an update. The left (or right) mouse button take extra click(s) to work. I originally thought it was the mouse going bad, I switched mouse buttons in the control panel the same thing happen to the other button. I disabled real time scan briefly, then it worked a lot better. Anyway to report this bug?
A:Possible Mouse bug in Microsoft Security Essentials in an update
I have MSE and do not have the mouse button problem you have.
3 more replies
Left for work this morning and all was fine. came home and saw my pc had rebooted. Then i noticed there was no mouse pointer...... a few keyboard shortcuts later and i had a desktop. Windows told me it had installed some automatic updates and restarted my pc. Now there is no mouse pointer and when i remove and re-insert my mouse windows trys to install it then fails telling me the following:
"windows found driver software for your device but encountered an error while attempting to install it.
HID-compliant device
An error occured during the instalation of the device.
The driver instalation file for this device is missing a necesary entry. This may be because the INF was written for Windows 95 or later. Contact your hardware vendor.
If you know the manufactor of your device, you can visit its website and check the support section for driver software."
This is a joke!! A mouse is fundamentally the most important thing outside the box a pc needs to work as its meant to.... I have tried 3 mice - all usb - my logitech mx laser, a microsoft optical 2 button wheel mouse, and some other unmarked 2 button mouse and ALL come up with this error. I really wish MS would fully test their updates before releasing them - especially with auto updates happening nowadays.
Has anyone got any ideas how i can fix this problem please? I have Vista Ultimate x64 OEM - genuine and fully updated.
A:Auto Update today killed my mouse
UPDATE:
ive just installed the 64 bit vista drivers from logitech and the mouse still has no pointer and doesnt move ( taskbar doesnt come up when mouse pulled to bottom of screen). When i check the mouse properties in device manager it is an "unknown device", however when i tell it to update the driver and point it to the logitech directory it tells me the best driver is already installed - the logitech driver !!!! so if it knows what it is, then why is it still unknown?????
Luckily i have a dula boot with xp pro... so, once again ive to hold my vista and revert back to xp untill ms supply a fix for this.....
thanks again.
26 more replies
Hi! I am having trouble with my chromebook after the last update that I accepted last week. Because of the new update, my mouse touch does not work and I am having trouble using it since I still need to plug the mouse before it runs. My chromebook runs perfectly until the update happened. What should I do? I hope I can hear from you soon. Thanks HP!
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just restart and updated my laptop and my mouse just wasn't working after rebooting. before i updated no problem with the mouse. the last time i fixed this was with a system restore but now i'm trying to find an alternative to that since it's time consuming. drivers aren't saying it's corrupted or missing or outdated. i can verify that this mouse is working because i tested it on my desktop and tried using another mouse and ends up the same. tried uninstalling and reinstalling the drivers and didn't do anything. tried disabling and enabling it still nothing. also after a few minutes that the mouse is connected my laptop it plays the "USB device removed" ringtone and plays the "USB device detected" ringtone afterwards. maybe it's connected to my problem i don't know thought that you might know why it happens. please help thanks.
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After updating with KB2507938, his USB wireless mouse and keyboard stop working. Apparently his regular, wired keyboard works. Doing a System Restore fixes the problem, but after turning the computer off and then on, etc., the update reapplies itself.
A:Friend's USB mouse and keyboard don't work after an update
Please perform the following, so that we can get the exact specs of your computer. This will better assist us in helping you more.Publish a Snapshot using SpeccyThe below is for those who cannot get onlinePlease take caution when attaching a text file to your post if you cannot copy/paste the link to your post, you will need to edit it to make sure that your Windows Key is not present.
34 more replies
I am trying to install a remote new mouse wont update settings when I plug it in my usb port ?
Thank you
Logitech mouse
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I re-downloaded Microsoft software for my Sculpt Bluetooth Mouse still cannot get the PC to see the mouse. It doesn't show in Hardware Manager or anywhere else. If I try to download again it says its already in download folder but that doesn't allow computer to see mouse....any help is greatly appreciated
A:Bluetooth mouse inop since update 14328
Can you double click and run the program in the download folder?
5 more replies
On Thursday (9/22/2016) the computer in question ran a Windows Update and upon rebooting the computer, a co-worker notified me that the USB (wired) keyboard & mouse were no longer working. I have been searching to find a solution and among those solutions, I have only been able to attempt updating the BIOS. After updating the BIOS (from AMB v80.07 to AMB v80.11 [System Board ID: 2B08]) the same problem exists. I was hoping that the BIOS update would reveal the option in setup to disable XHCI, as that has seemingly been the active solution for this problem that I have seen in many forum posts, but I still do not see the option to disable XHCI nor have I been able to find a viable source as to how to reveal the option so that I may disable it and see if it actually is the solution I need. All options I have tried thus far have not worked including: Updating the BIOS, restoring Windows to a restore point (9/20/2016 was the only restore point I had), and using a different USB Port as well as using a different USB keyboard & mouse AND a wireless keyboard & mouse. The only options I have yet to explore are a full restore, which we are trying to avoid because of the files we have on the hard drive of the computer in question (which I can just place into another one of the computers we have and extract if necessary). I have not been able to find a sufficent way to uninstall the keyboard/mouse drivers from the System Recovery boot-up screen as I am unable t... Read more
More replies
As per title - I decided to update my Win 7 ultimate to SP1 which installed ok but I ended up with a black screen with working mouse cursor and a message box showing something like - "configuring user settings".
This stayed like this for a long time and in the meantime I used CTRL_ALT_DEL to try to run Firefox to get on to the net. Firefox failed to open which appeared to indicate something network related.
I finally shutdown via the taskmanager and booted to Safe mode - with networking. Trying to open a browser resulted in a painful wait which I gave up on. It appeared that it couldn't download anything.
I then did a system restore and got back to full working system. My Windows 7 has been extremely stable and I've no problems. I did a virus check and loaded the update readiness tool but haven't tried SP1 again.
I decided to search around but really this kind of issue seems like it could be caused by a lot of things and I've no clear answer to what is my specific issue. Given the problems with networking issues (eg. some people had suggested they unplugged the LAN cable as their Qnap nas was the problem - beats me but I have a Qnap), maybe it is this.
I doubt it's graphics although originally I suspected it but I do have the latest drivers installed and now I'm back after system restore this is stable as ever.
I'm really searching for either:
1) the best (quickest) way to troubleshoot this problem
or
2) a way to update to SP1 bit by bit - if that's possibl... Read more
A:After SP1 update - black screen with mouse cursor
Why would you install Windows 7 without SP-1?
Where did you get your copy of Windows 7 Ultimate?
With SP-1 installed you will still have over 200 more updates.
2 more replies
I do not have a Lenovo -machine or mouse. It is a Logitech usb mouse M325
I knew I did not have anything Lenovo but there it was waiting to be installed.
The choice to upgrade drivers is turned on
Meanwhile my mouse went into poor response while in Adobe Lightroom which prompted me to investigate the logs.
Although it downloaded and installed the CBS.log indicates it didn't install. Searching results in no Lenovo. The name just remains in the list of updates installed.
I downloaded the current Logitech setpoint update 6.7 and the mouse returned to normal.
The questions are
.....Turn off upgrade drivers (and hope it sticks)?
.....how would this update download be refused?
.....If this record is in the list of installed updates will it encourage future inaccurate device info downloads?
A:Update delivers Lenovo Optical Mouse
Have a look at this tutorial :
Device Driver Automatic Installation - Turn On or Off in Windows 10
0 more replies
I had a problem with my yoga 700 11". The laptop freezes every so often (3-6 hours). At first I thought it's the drivers that need to be updated, then Windows 10 updates, then BIOS update.I tried all of that but the problem still persisted. I did the recovery reset but still the same... I created Linux system on USB flash drive and booted the laptop with it. Even under Linux the laptop was freezing.I contacted lenovo support team and they said the laptop needs to be repaired and they send me the return free postage vocher. I put my laptop in the original box and posted it as I was instructed (for some reason it was send to Germany). The company name that issued me with the postage slip was MEDION AG - A Lenovo CompanyAfter 13 days I got an email saying:"...After assessing your device, the repair center has deemed that a repair cannot be completed under the manufacturer?s warranty due the case of the device showing signs of inappropriate treatment. ..." There were two pdf documents attached to the email. one with the detailed photos of the damage ( see photo attached) and the other one, the cost estimate document. In the document I was given two options:1. accept the cost of repair (£54.65)2. not accept and the laptop would be return to me (I would be still charged fat price of £44.07)My reply was that I do not recall the laptop having this damage and I always looked after it. I was suprised when I saw the photo. I also added that my main concern was that th... Read more
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ok, i know i have malware on my computer. i read the 5 steps to do first....
step one-
i ran ad-aware (i have pro edition), no problems found,
aswell as spy bot s& d and cwschredder, all fine
syep two-i have norton and avg, no problems
step 3-none from that list
step 4-none from that list
step 5-can't update from windows, just get errors
here is my hijack this log:
Logfile of HijackThis v1.99.1
Scan saved at 9:57:51 AM, on 5/10/2006
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Windows Defender\MsMpEng.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Documents and Settings\Administrator.JBOOGY\Local Settings\Temporary Internet Files\Content.IE5\ZQQBBUH0\stng260[1].exe
C:\Program Files\a-squared\a2guard.exe
C:\WINDOWS\system32\ntvdm.exe
C:\WINDOWS\explorer.exe
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://us.rd.yahoo.com/customize/yco...search/ie.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://us.rd.yahoo.com/customize/yco.../www.yahoo.com
R0 - HKLM\Software\Microsoft\Inte... Read more
A:ok, difinitely need help. i have completed the five steps
Hi,
Quote:
If you are seeking help for spyware/antivirus issues, or wish to have your Hijack This log checked, please do not post here!
Post it at the HijackThis Log Help section. I think I mod will move this post.
5 more replies
I've ran Combofix, but need someone to look at my log file. I'm still having boxes pop up like my symantic anti-virus can't work because it is on a network resource that is unavailable. The log file is below. I would really appreciate any help I could get.Thanks,DonComboFix 10-12-09.04 - Todd 12/10/2010 16:39:31.1.1 - x86Microsoft Windows XP Professional 5.1.2600.3.1252.1.1033.18.511.70 [GMT -6:00]Running from: c:\documents and settings\Todd.PHILCON\Desktop\ComboFix.exeAV: Symantec AntiVirus Corporate Edition *On-access scanning disabled* (Updated) {FB06448E-52B8-493A-90F3-E43226D3305C}.((((((((((((((((((((((((((((((((((((((( Other Deletions ))))))))))))))))))))))))))))))))))))))))))))))))).c:\documents and settings\All Users\Application Data\FuhYQAtN.exec:\documents and settings\Don\Local Settings\Application Data\{127EBD9A-1C22-44C3-8173-3067BB23059B}c:\documents and settings\Don\Local Settings\Application Data\{127EBD9A-1C22-44C3-8173-3067BB23059B}\chrome.manifestc:\documents and settings\Don\Local Settings\Application Data\{127EBD9A-1C22-44C3-8173-3067BB23059B}\chrome\content\_cfg.jsc:\documents and settings\Don\Local Settings\Application Data\{127EBD9A-1C22-44C3-8173-3067BB23059B}\chrome\content\overlay.xulc:\documents and settings\Don\Local Settings\Applicat... Read more
A:Combofix completed - need help with log file
2 more replies
I just started using Microsoft 2010 and in the Outlook tasks I have created recurring tasks. In the old XP version when I completed a recurring task, the completed task would move to the top of the list. Now, it just puts it below the original task. Is there a way to automatically move completed tasks to the top of the page?
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Deckard's System Scanner v20070905.67
Run by Tom Roach on 2007-10-01 10:32:34
Computer is in Normal Mode.
--------------------------------------------------------------------------------
-- System Restore --------------------------------------------------------------
Successfully created a Deckard's System Scanner Restore Point.
-- Last 5 Restore Point(s) --
104: 2007-10-01 14:32:38 UTC - RP355 - Deckard's System Scanner Restore Point
103: 2007-10-01 14:17:25 UTC - RP354 - Installed WinZip 11.1
102: 2007-09-30 07:00:16 UTC - RP353 - Software Distribution Service 3.0
101: 2007-09-29 17:11:48 UTC - RP352 - Removed Adobe? Photoshop? Album Starter Edition 3.2
100: 2007-09-29 16:55:46 UTC - RP351 - Installed Windows Internet Explorer 7.
-- First Restore Point --
1: 2007-09-24 19:33:06 UTC - RP252 - System Checkpoint
Backed up registry hives.
Performed disk cleanup.
-- HijackThis (run as Tom Roach.exe) -------------------------------------------
Unable to find log (file not found); running clone.
-- HijackThis Clone ------------------------------------------------------------
Emulating logfile of HijackThis v1.99.1
Scan saved at 2007-10-01 10:39:35
Platform: Windows XP Service Pack 2 (5.01.2600)
MSIE: Internet Explorer (7.00.6000.16512)
Running processes:
C:\WINDOWS\system32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
A:WinAntiVirusPro - 5 steps completed
2. Double click on combofix.exe & follow the prompts.
3. When finished, it shall produce a log for you. Post that & a fresh Hijackthis log in your next reply
Note:
Do not mouseclick combofix's window whilst it's running. That may cause it to stall
13 more replies
Hi, I just built a new computer, and it's running XP Pro 64-bit. It ran fine for the first week, but now I'm getting a problem everytime I open "My Computer". Instead of showing my drives, it does the search animation. After a minute or two, it will either find all the drives, or it will say something like "This operation could not be completed because (something) is being used by another program." and gives me two options: "Retry", or "Switch To". When I click "Switch To" it opens my "Start" menu.
A (possibly) related problem is when I open IE, I get shown a set-up menu, but when I click "Save Changes" the webpage hangs. I can bypass this and use the internet fine though. Also, my computer randomly hangs sometimes when playing games.
I'm pretty disappointed with all these errors on what was supposed to be my fresh computer... Any help is appreciated.
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Not sure if this is the correct forum to post this in but..
Have installed Windows 8 64bit on three computers, all similar spec (amd a8 processors and gigabyte f2 motherboards with 8gig ram.)
Windows seems to be ok in every other respect other than I am getting an error in the metro store. When trying to install any app I get the error:
I have searched the internet for this error, and although I can find similar errors, I can see no one else having the error code with the same scrambled type.
We got around the error by signing in to a microsoft account, but then we are unable to create a pin for said account (the cursor just spins).
This happens on all three computers.
Any help greatly appreciated.
A:your purchase couldn't be completed
Have you tried copying & pasting the error code in Google ?
I find that helps.
EDIT--
I Googled & found nothing.
Perhaps this phone number will help.
I've used it & got good help from Microsoft.
Microsoft Product Support Customer Phone Number | Shortest Wait | Best Support | GetHuman.com
2 more replies
log listed below : DO YOU WANT THE PANDA SCAN SCAN ALSO?
had constant pop ups- they have stopped- system very slow..avast found virus in operating system-win32:agent-PSG [drp] and vtutr.dll -
trojans
I just know how to computer surf- my son goes to online school- so we really need this computer
log listed below
Deckard's System Scanner v20071014.68
Run by wpccs on 2008-02-03 18:09:34
Computer is in Normal Mode.
--------------------------------------------------------------------------------
-- System Restore --------------------------------------------------------------
System Restore is disabled; attempting to re-enable...success.
-- Last 1 Restore Point(s) --
1: 2008-02-03 23:09:39 UTC - RP1 - System Checkpoint
Backed up registry hives.
Performed disk cleanup.
Total Physical Memory: 248 MiB (512 MiB recommended).
-- HijackThis Clone ------------------------------------------------------------
Emulating logfile of Trend Micro HijackThis v2.0.2
Scan saved at 2008-02-03 18:13:54
Platform: Windows XP Service Pack 2 (5.01.2600)
MSIE: Internet Explorer (6.00.2900.2180)
Boot mode: Normal
Running processes:
C:\WINDOWS\system32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
A:hijackthis log- completed 5 steps
Hi dorimom, and welcome to TSF.
Sorry for the delay in looking into your log, as we are extremely busy as you may have noticed. If you still require assistance and are not seeking help elsewhere, then please carry out my instructions.
Please subscribe to this thread so that you are notified when you receive a reply. To do this click Thread Tools, then click Subscribe to this Thread. Make sure it is set to Instant Notification, then click Add Subscription.
--------------------------------------------------------------
Please download HijackThis. This program will help us determine if there are any spyware/malware on your computer. Double-click on the file you just downloaded. Click on the "Install" button. It will by default install to the directory - C:\Program Files\Trend Micro\HijackThis
Close HiJackThis
--------------------------------------------------------------
Since it has been awhile... Please run Deckard's System Scanner (dss.exe) again, and post the resulting log.
--------------------------------------------------------------
C:\Deckard\System Scanner\main.txt
5 more replies
Hello TSF -
Recently, i have had a problem with my system restore. After i attempt a restore, the computer reboots fine and acts as if it did the restore, but when i sign it, i get a messege saying system restore incomplete, or something along those lines. I decided to check the sr.inf file, right clicked and clicked install, but it said i need a windows XP sp3 cd, and i only have the original SP2 cd, not Sp3. Also i'm not sure if that will even fix the probem, has anyone else seen this problem? any help would be greatly appreciated!
-Thank you.
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Hi
Looking for some help resolving this issue. Computer was acting strange. Scanned with Norton 360 and Malwarebytes and found nothing. Ran TDSSkiller, found and removed a rootkit. Now, when I try to run Combofix, it stops at Stage 48. The hard drive light is solid, so I figured it would eventually complete, but it does not.
Can you help?
thanks
drobtoy
A:stuck on 'Completed Stage_48'
Hello,Please follow the instructions in ==>This Guide<== starting at step 6. If you cannot complete a step, skip it and continue.Once the proper logs are created, then post them in a reply to this topic by using the Add Reply button.If you can produce at least some of the logs, then please create the post and explain what happens when you try to create the log(s) that you couldn't get. If you cannot produce any of the logs, then still post the reply and explain that you followed the Prep. Guide, were unable to create the logs, and describe what happens when you try to create the logs.
19 more replies
hi there,
plese consider that who's writing (me) is a sw/hw total illiterate..
months ago i downloaded a .exe (then uninstalled) to upload videos on youtube and from that time:
- at every web connection (firefox), the start page is http://istart.webssearches.com + the last web page visited at previous connection (two windows). i set up new homepage but nothing changes.
- pop ups frequently open (then disabled via settings).
- mouse stops/blocks for a second while using it.
i downloaded combofix and let it run. everything seems worked correctly, but now i don't know how to proceed.
here below the log i got - integral copy&paste - now saved on desktop.
if i understood well, malware etc will be removed once combofix is uninstalled and i still have to uninstall it..
i hope you can help me about how to proceed.
thanks++
iggy
ComboFix 14-05-19.01 - user 19/05/2014 19.13.03.1.1 - x86
Microsoft Windows XP Home Edition 5.1.2600.3.1252.39.1040.18.1919.1432 [GMT 2:00]
Eseguito da: c:\documents and settings\user\Desktop\ComboFix.exe
AV: avast! Antivirus *Enabled/Updated* {7591DB91-41F0-48A3-B128-1A293FD8233D}
.
.
((((((((((((((((((((((((((((((((((((( Altre eliminazioni )))))))))))))))))))))))))))))))))))))))))))))))))))
.
.
c:\documents and settings\All Users\Dati applicazioni\kp_0loor.pad
c:\documents and settings\user\Dati applicazioni\cacaoweb
c:\documents and settings\user\Dati applicazion... Read more
A:ComboFix ran&completed - don't know how to proceed
3 more replies
Hi, I have already run Ad-aware using the required settings multiple times and removed everything I can on my own. Ad-aware could not remove iboboi.dll and I believe that is the root of my problem. But on startup that file is gone.
Here is my hijack this log, with the analyzer. Thank you in advance for the help!
===========================================================================================================================
Log was analyzed using HijackThis Analyzer - Updated on 1/7/05
***Security Programs Detected***
C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe
C:\Program Files\Norton AntiVirus\navapsvc.exe
C:\Program Files\Common Files\Symantec Shared\ccApp.exe
O2 - BHO: NAV Helper - {BDF3E430-B101-42AD-A544-FADC6B084872} - C:\Program Files\Norton AntiVirus\NavShExt.dll
O3 - Toolbar: Norton AntiVirus - {42CDD1BF-3FFB-4238-8AD1-7859DF00B1D6} - C:\Program Files\Norton AntiVirus\NavShExt.dll
O4 - HKLM\..\Run: [ccApp] "C:\Program Files\Common Files\Symantec Shared\ccApp.exe"
O4 - HKLM\..\Run: [ccRegVfy] "C:\Program Files\Common Files\Symantec Shared\ccRegVfy.exe"
O23 - Service: Symantec Event Manager - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe
O23 - Service: Symantec Password Validation Service - Symantec Corporation - C:\Program Files\Common Files\Symantec Shared\ccPwdSvc.exe
O23 - Service: Norton AntiVir... Read more
A:Urllogic Pop-ups, completed all prereqs
Let's see if these logs will show us anything:
The Temp folders should be cleaned out periodically as installation programs and hijack programs leave a lot of junk there. Download CleanUp! (Alternate Link if main link don't work) and install it. Do not run it yet.
Before doing anything, MAKE SURE that you can keep your computer on (at least until we get it fixed). This infection requires us to detect and remove it without rebooting or restarting your computer (unless the instructions say so). If you can't keep your computer on today, then I suggest that you don't get the logs yet until you are ready. With that said (when ready):
Open up HijackThis and go to Config->Misc Tools and check the first two boxes there. Now click on the Generate StartupList log button. Post that log in your next post.
Right click on this link and choose Save As...Save it to your Desktop. Make sure you have disabled any programs that may block/disable scripts (ex: Ad-Watch, TeaTimer, Norton, etc.). Double click on Silent Runners to run it. This will take a few minutes. It will create a file called Startup Programs followed by your computer name and current date. Open up that file and post all the contents here in your next post.
Download Find-qoologic. Unzip the files to your Desktop. Open the qoologic folder and run the qoologic.bat file. Wait a few minutes for it to finish. When the dos window disappears, go to your C: drive and open up the log.txt file. Copy and p... Read more
7 more replies
The action can?t be completed because the folder or a file in it is open in another program. I suspect that my anti virus, Norton 360, is stopping me from deleting a specific folder, it happens only in one specific folder.
When I restart my computer, it takes time to the regular background tasks to "wake up", so I can delete it once the computer turns on, but then something stops me from deleting the folder. I am not sure if it is Norton 360, or another problem.
Would it be a Malware?
A:The action can’t be completed because the folder or a f...
not positive what it could be ,anything knowing computers .
to see if its Norton 360. disconnect from intern ,disable Norton360 temporally ,how to do so will be in the settings of Norton , after its disable try deleting file.
just found this in google ,how to disable Norton temporally .
Try right clicking on the 360 icon in your notification area. You should be able to disable protection features for a specified time. Remember that you are unprotected while doing this, so you should disconnect from the Internet while doing this. Remember to reset the protection when you are finished.
6 more replies
hi guys,
every single time I try to rename a folder the boring message "The action can't be completed because the folder or the file is in use" appears even if apparently neither the folder or a file in it is in use.
What I have to do is: Task Manager > Explorer.exe > End Process > File > New Task > Explorer.exe and I am able to rename the folder.
It is a really boring process and I find this process really stupid. The folders I am trying to rename are full of pictures, I think it is something related to the Thumbs files.
Anybody of you have the same issue? Any possible solution?
Thanks
A:PLEASE HELP - The action can't be completed because the folder....
OpenedFilesView - View opened/locked files in your system (sharing violation issues)
What file is opened by explorer.exe in that folder?
9 more replies
Hi I just completed my second homebuild, I installed windows 7 pro and have been running it for over two weeks now, (got it pre release from msdna for free, thats right free, gotta love being a student, as many copies of 7, vista, xp and visual studio, and tons of other cool software for nada.)
anyway:
asus m4a78-e mobo
8gb (4x2gb) ddr3 ram
amd phenom II 945 3.0ghz quad core processor.
xfx hd 4850 1gb gddr3 gpu 256 bit with 512mb onboard already
2 x 500gb hitachi deskstar hdd's
sunbeam acb9 acrylic green led pc case (12 green leds, with 5 80mm green led fans, and custom fan grills.)
19" tft
650tx corsair psu
onboard sound and networking
it works great, so far I haven't seen the cpu go over 8% you through stuff at it it gives you a blank look and shrugs, it took a virus scan, dreamweaver, word and a few web pages (chrome) at 8% for god's sake. Anyway i'm very pleased with it.
BUT it only lists one hdd in the my computer section and that is the drive that i installed windows on, I don't know if the other one is formatted or not, I would say not, the bios recognises both of them, but my computer displays only one, i have not used raid in any form. Whats the solution?
Thanks alot, bob.
A:New build completed, but second hdd not recognised by os?
you shoud try this :
On "My Computer" Icon right click it and click MANAGE, click on DIsk Management..you may find your C: drive as Disc 0. Then look if you find drives that is unallocated..if you find it, click on the on it, right click and format the drive and click ok..just wait to make a 100% and you should after that it is healthy and formatted and you should the other drives now..try this tnx
3 more replies
G'day, I'm running Windows 7 Home premium on a Dell Inspiron laptop.
When I am trying to organise my music files and folders in my music Library I randomly get this error:
The action can't be completed because the folder or a file in it is open in another program.
But there can be nothing else open, no media player, (neither WMP or Media Monkey which I usually use), or any other window open at all. This is intermittent. Sometimes it works sometimes it doesn't.
For example; I just discovered that I have a Chris De Burgh folder with a couple albums in it and another folder titled Chris De Burgh - Greatest Hits. I decided to move the latter into the former and rename the latter to simply Greatest Hits. At first it wouldn't copy into the Chris de Burgh folder at all and the dreaded error came up. I clicked on another folder, went back and tried again and it worked. After putting the CDB-GH folder into the CDB one I tried to rename it, (without opening it). The action can't be completed blah blah blah. Retry doesn't work. This time I had to close windows explorer and open it again and browse to the folder and rename it.
Sometimes it works first go, sometimes you have to click elsewhere then come back to it, sometimes you have to close explorer, sometimes it simply refuses until I restart the pooter. I've tried deleting everything in the temp folder, (%temp%) but there are files in here which won't delete either coming up with the same message. I guarantee that the f... Read more
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I apologize if this forum is meant for tech people as I'm a novice computer user, but I really need help. I have Windows 7 x64 and I used RoboCopy for the first time, and have messed up royally. I was trying to copy folders and files from my
computer to an external hard drive. My external hard drive had important files and folders on it already, and I thought that copying more data using RoboCopy would just add to it, but it deleted everything that was on the external hard drive when it
copied the additional data.
Can I undo what just happened? Is there any way to revert? Or maybe there's some way to recover that deleted data?
I used: Robocopy C:\Users\Name\Documents F:/MIR /dcopy:T
I would be really grateful to be helped. Thanks in advance.
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I've run CHKDSK on a couple of laptops today, and in each case, after hanging for ages around 10-11%, the laptop rebooted while my back was turned. (The process was run at boot and the internet was not connected at the time.)
Is there a way to check if the process completed and what it did?
There is a CBS log with today's date, with entries that correspond time-wise to the CHKDSK activity, but I don't understand them. At the end there are several entries like this:
Can anyone explain what this means please, and if I have a problem?
Coincidentally (or not) There are similar 'Failed to internally open....' entries in the CBS log from when I turned the laptop back on later in the morning.
A:How do I know if CHKDSK completed successfully?
Hi, check this tutorials CHKDSK - Check a Drive for Errors in Windows 8 and Check Disk (chkdsk) - Read Event Viewer Log - Windows 7 Help Forums to see if they will help you.
Good luck, werty
3 more replies
Trying to restart will not allow me to login, keeps telling me wrong pass word, (didn't think i had setone yet)think its microsoft thats causing the problem, it says i need a removeable media, what the hell is one ofthem. i'm already on line at home. Can anyone help me please
A:New netbook setup not completed,
Hello, Thank you for posting in the HP Support forum. Is this re. Windows login ? You can't login to Windows? If yes, I have encounter such a problem once only but was with Win 8. Anyway - if this is a new computer you can revert the software back to factory default settings. Eventually you should create a local account (not login with Microsoft account). At the end, you can always migrate the local account to Microsoft account. If this is not re. Windows login, please provide back details.
1 more replies
Computer has a very slow startup. I cannot get rid of this Kodak Easyshare. Internet response time a bit faster, page to page.Logfile of Trend Micro HijackThis v2.0.2Scan saved at 05:44, on 2008-03-19Platform: Windows XP SP2 (WinNT 5.01.2600)MSIE: Internet Explorer v7.00 (7.00.6000.16608)Boot mode: NormalRunning processes:C:\WINDOWS\System32\smss.exeC:\WINDOWS\system32\winlogon.exeC:\WINDOWS\system32\services.exeC:\WINDOWS\system32\lsass.exeC:\WINDOWS\system32\svchost.exeC:\WINDOWS\System32\svchost.exeC:\WINDOWS\system32\spoolsv.exeC:\Program Files\Common Files\AOL\ACS\AOLAcsd.exeC:\Program Files\Common Files\AOL\TopSpeed\2.0\aoltsmon.exeC:\Program Files\Common Files\AOL\1101823440\ee\services\safetyCore\ver210_5_2_1\aolavupd.exeC:\WINDOWS\system32\cisvc.exeC:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exeC:\WINDOWS\system32\lxczcoms.exeC:\WINDOWS\Explorer.EXEC:\Program Files\mcafee.com\personal firewall\MPFService.exeC:\WINDOWS\System32\svchost.exeC:\WINDOWS\wanmpsvc.exeC:\WINDOWS\system32\fxssvc.exeC:\WINDOWS\system32\wscntfy.exeC:\WINDOWS\system32\hkcmd.exeC:\Program Files\MUSICMATCH\... Read more
A:All Steps Completed Up To Hijack
Sorry for the delay. If you are still having problems please post a brand new HijackThis log as a reply to this topic. Before posting the log, please make sure you follow all the steps found in this topic:Preparation Guide For Use Before Posting A Hijackthis LogPlease also post the problems you are having.
1 more replies
Dear Broni and All,
I have completed all steps, and ran the security programmes recommended in this thread:
http://www.techspot.com/community/topics/keep-getting-stupid-shopping-malware-installed.208648/
However, I am still getting pop-ups and adware related problems, which means that the underlying problem has not been resolved.
These are the programmes that I have run (today, 18/05/2015):
-RogueKiller
-Mbar
-AdwCleaner (it removed NickelBlock, AllCheeiaPPPriCe, DowwnSaave, SaVieNeewaApupoz)
-Junkware Remover
-Farbar Recovery Tool
-Farbar Security Scanner
-Security Check
-Tempfile Cleaner
I am currently running Sophos.
My laptop runs Windows 8.1, and Combofix does not support it.
The antivirus that I have is Kaspersky (I previously had Microsoft Security Essential), and Windows Defender. The malware was not detected by a Kaspersky and Spybot full scan a few days ago. However, on the 26th of April, I manually uninstalled some adware, and then ran full scans, which showed nothing.
As you can imagine, I don't think I have many options left, and formatting my laptop is a dreadful prospect. I was wondering if you could give me some advice.
I have kept all logs of the security programmes that I've run.
Thank you in advance, and looking forward to hearing from you.
A:Completed all instructions, but still getting adware pop-ups
Welcome aboard
Never follow steps from other topics. Every computer is unique.
Please, complete all steps listed here: http://www.techspot.com/vb/topic58138.html
Make sure, you PASTE all logs. If some log exceeds 50,000 characters post limit, split it between couple of replies.
Attached logs won't be reviewed.
Please, observe following rules:
Read all of my instructions very carefully. Your mistakes during cleaning process may have very serious consequences, like unbootable computer.
If you're stuck, or you're not sure about certain step, always ask before doing anything else.
Please refrain from running any tools, fixes or applying any changes to your computer other than those I suggest.
Never run more than one scan at a time.
Keep updating me regarding your computer behavior, good, or bad.
The cleaning process, once started, has to be completed. Even if your computer appears to act better, it may still be infected. Once the computer is totally clean, I'll certainly let you know.
If you leave the topic without explanation in the middle of a cleaning process, you may not be eligible to receive any more help in malware removal forum.
I close my topics if you have not replied in 5 days. If you need more time, simply let me know. If I closed your topic and you need it to be reopened, simply PM me.
57 more replies
A neighbor brought over his computer since he knows I help folks with infections. It appears he already ran and removed infections found with SAS Portable and MBAM. I can include those logs if you like so let me know.
DDS Log
DDS (Ver_2012-11-20.01) - NTFS_x86
Internet Explorer: 8.0.6001.18702 BrowserJavaVersion: 10.25.2
Run by HP_Administrator at 12:32:46 on 2013-08-16
Microsoft Windows XP Professional 5.1.2600.3.1252.1.1033.18.958.456 [GMT -4:00]
.
AV: avast! Antivirus *Enabled/Updated* {7591DB91-41F0-48A3-B128-1A293FD8233D}
.
============== Running Processes ================
.
C:\Program Files\AVAST Software\Avast\AvastSvc.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\eHome\ehRecvr.exe
C:\WINDOWS\eHome\ehSched.exe
C:\WINDOWS\system32\wdfmgr.exe
C:\Program Files\AVAST Software\Avast\avastUI.exe
C:\WINDOWS\System32\alg.exe
C:\WINDOWS\system32\dllhost.exe
C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
C:\WINDOWS\system32\wbem\wmiprvse.exe
C:\WINDOWS\system32\svchost.exe -k netsvcs
C:\WINDOWS\system32\svchost.exe -k NetworkService
C:\WINDOWS\system32\svchost.exe -k LocalS... Read more
A:Infected PC with some Removal Completed
Attached file ...
3 more replies
I got my P50 a few weeks ago and yesterday its LCD went half black. OK, this happens.I turned it into authorized premium repair center and they got LCD replaced (as my P50 is under warranty). No big deal.However, they could not re-calibrate the new LCD screen because I do not run Windows on my P50 (running Kubuntu).It would not be a big deal either (the Panel Replacement Utility they have does not run on Linux, but I can live without that), however there is one worrying thing: by my request, they printed Lenove repair instructions for me where it is stated, that "Failing to run the Panel Replacement Utility program will require another LCD panel replacement". Please note "will require". My interpretation of this statement is that LCD will fail again unless I run this Panel Replacement Utility which requires Windows (not Linux version exists). Repair guys could not comment on that in either direction.REALLY????So, despite the fact that nor P50 user guide nor warranty description limit me from using non-Windows OS, the P50 cannot be repaired to be used in full capacity unless I use Windows.Do I miss anything? Is this an official position of Lenovo on non-Windows OS use on ThinkPad P50?
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I recently had a virus and used HP recovery and now I don't have any sound. I originally posted this in the sound card forum and was instructed by deejay100six to go through the five steps of identifying a virus. I completed those steps and below is my Panda Scan results. I have the hijackthis results when ever you need them. I originally went through all of the basic steps to fixing the sound problem but nothing worked. Thanks again in advance.
ANALYSIS: 2008-08-16 02:24:44
PROTECTIONS: 1
MALWARE: 19
SUSPECTS: 2
;***********************************************************************************************************************************************************************************
PROTECTIONS
Description Version Active Updated
;===================================================================================================================================================================================
avast! antivirus 4.8.1229 [VPS 080815-0] 4.8.1229 Yes Yes
;===================================================================================================================================================================================
MALWARE
Id Description Type Active Severity Disinfectable Disinfected Location
A:No Sound/5 steps completed
I need some help here guys. Below is my hijackthis results.
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 10:35:50 AM, on 8/23/2008
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16705)
Boot mode: Normal
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Common Files\LogiShrd\LVMVFM\LVPrcSrv.exe
C:\Program Files\Java\jre1.6.0_07\bin\jusched.exe
C:\windows\system\hpsysdrv.exe
C:\WINDOWS\system32\hkcmd.exe
C:\Program Files\HP\hpcoretech\hpcmpmgr.exe
C:\WINDOWS\System32\hphmon05.exe
C:\HP\KBD\KBD.EXE
C:\Program Files\iTunes\iTunesHelper.exe
C:\WINDOWS\AGRSMMSG.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\igfxtray.exe
C:\Program Files\Common Files\LogiShrd\LComMgr\Communications_Helper.exe
C:\Program Files\Logitech\QuickCam\Quickcam.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\WINDOWS\ALCWZRD.EXE
C:\WINDOWS\ALCMTR.EXE
C:\WINDOWS\system32\agrsmsvc.exe
C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
C:\WINDOWS\System32\gearsec.exe
4 more replies
I am using SQL Server 7.0.
I have databases DB1 (only current values) and DB2 (both current and old - keeps history). When I update (or insert), on DB1, a copy of the row I am working on has to be sent to DB2 using a trigger. What gets completed first? The update process on DB1 or the action started by the trigger? I am asking this because of what I found at this site:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/architec/8_ar_da_1tup.asp
…..
You can use the FOR clause to specify when a trigger is executed:
AFTER
The trigger executes after the statement that triggered it completes. If the statement fails with an error, such as a constraint violation or syntax error, the trigger is not executed. AFTER triggers cannot be specified for views, they can only be specified for tables. You can specify multiple AFTER triggers for each triggering action (INSERT, UPDATE, or DELETE). If you have multiple AFTER triggers for a table, you can use sp_settriggerorder to define which AFTER trigger fires first and which fires last. All other AFTER triggers besides the first and last fire in an undefined order which you cannot control.
AFTER is the default in SQL Server 2000. You could not specify AFTER or INSTEAD OF in SQL Server version 7.0 or earlier, all triggers in those versions operated as AFTER triggers.
…..
This statement sounds confusing?
A:Which is completed 1st? a transaction or a trigger?
Enforcing Business Rules with Triggers
Microsoft® SQL Server™ 2000 provides two primary mechanisms for enforcing business rules and data integrity: constraints and triggers. A trigger is a special type of stored procedure that automatically takes effect when the data in a specified table is modified. A trigger is invoked in response to an INSERT, UPDATE, or DELETE statement. A trigger can query other tables and can include complex Transact-SQL statements. The trigger and the statement that fires it are treated as a single transaction, which can be rolled back from within the trigger. If a severe error is detected (for example, insufficient disk space), the entire transaction automatically rolls back.
This means that the trigger completes before the transaction, you can rollback a transaction within a trigger as mentioned above so in your case the action started by the trigger completes before the update action.
2 more replies
Recently installed kaspersky pure 2. 0 .Getting error message that backup task has not been completed. I have read that this is a known issue. Is there a solution to correct this problem? Thanks.
A:backup task has not been completed
Welcome to Seven Forumsnancy159. As you say, this is a known issue
Quote:
5. Main known issues
The maximum size limit for Quarantine and Backup and Restore does not work.
Some application windows do not correspond to Microsoft computer management from keyboard standards.
Groups of windows cannot be closed through Windows 7 taskbar.
Application window cannot be closed through Windows 7 taskbar preview.
"A backup task has not been completed" status is displayed in the general protection status and in the Backup and Restore section when backup tasks are performed.
Protection parameters cannot be reverted to default values.
AVZ reports cannot be created under 64-bit operating systems.
In some cases, characters cannot be entered using the Virtual Keyboard in entry fields of web browsers or applications.
When in Safe Run mode, Microsoft Outlook Express (Windows Mail) email client may fail to display some email messages received from the standard Microsoft Windows environment.
Kaspersky PURE 2.0: commercial release (build 12.0.1.288)
Have you tried creating a backup task?
How to create a backup task in Kaspersky PURE 2.0?
A Guy
1 more replies
Hello,
Had the "Security Center" come up on this computer...got rid of it using the tutorials on this site, along with trying all the other suggestions for removing rootkits that may be causing the redirects. Some solutions seem to run their course, others don't. Still having issues: browser redirects, browsers stop working, MBAM errors, Start menu blank, "waiting for background programs to end" on shutdown.
So, not sure where to go from here. Help please.
.
DDS (Ver_2011-08-26.01) - NTFSAMD64
Internet Explorer: 9.0.8112.16421 BrowserJavaVersion: 1.6.0_30
Run by Chance at 6:41:48 on 2012-01-23
Microsoft Windows 7 Home Premium 6.1.7601.1.1252.1.1033.18.3895.2379 [GMT -7:00]
.
AV: Microsoft Security Essentials *Disabled/Updated* {108DAC43-C256-20B7-BB05-914135DA5160}
SP: Microsoft Security Essentials *Disabled/Updated* {ABEC4DA7-E46C-2F39-81B5-AA334E5D1BDD}
SP: Windows Defender *Disabled/Updated* {D68DDC3A-831F-4fae-9E44-DA132C1ACF46}
.
============== Running Processes ===============
.
C:\windows\system32\wininit.exe
C:\windows\system32\lsm.exe
C:\windows\system32\svchost.exe -k DcomLaunch
C:\windows\system32\svchost.exe -k RPCSS
c:\Program Files\Microsoft Security Client\Antimalware\MsMpEng.exe
C:\windows\System32\svchost.exe -k LocalServiceNetworkRestricted
C:\windows\System32\svchost.exe -k LocalSystemNetworkRestricted
A:Completed all self-help tutorials, still have rootkit
22 more replies
Hello and thank you for any help you may be able to give. I've gone through the five required steps before posting my logs for help.
I've run Spybot, Adaware and SuperAntiSpyware and can't seem to clear up whatever the issue is.
Following are the required log files (as well as the "extra" text file attached):
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 1:06:02 PM, on 1/8/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16574)
Boot mode: Normal
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\vtsphlxp.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\netdde.exe
C:\WINDOWS\System32\HPZipm12.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\wscntfy.exe
C:\Program Files\Java\jre1.6.0_03\bin\jusched.exe
C:\Program Files\ATI Technologies\ATI.ACE\cli.exe
C:\Program Files\YourWare Solutions\FreeRAM XP Pro\FreeRAM XP Pro.exe
C:\Program Files\SUPERAntiSpyware\SUPERAntiSpyware.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Windows Media Player\WMPNSCFG.exe
C:\Program File... Read more
A:HijackThis Log - completed 5 steps
bump
anyone?
19 more replies
Thanks a lot to everybody who paid attention to my problems with windows 7 installation.
Finally I went to my university and took from their a windows 7 pro dvd and everything worked perfect. I also managed to install the windows over both windows XP and 7 thanks to your advices and tutorials.
Thanks a lot once again from the not so hot now Greece
A:Installation completed with success!!!!
You're welcome! Thanks for posting back. It means a lot to those that have worked hard to help others when they come back with thanks.
2 more replies
Hello,
This is a follow-up to my original thread here -
http://www.sevenforums.com/crashes-d...ease-help.html
I completed 1 RMA with HP and the teleplan service center guys sent me the machine back with the note - no issues found, reloaded OS. This time they loaded the OS with SATA controller as IDE as opposed to the default RAID setting that had come when I had purchased the system.
I let it run overnight hoping for the best but see the BSOD error in morning - I would really appreciate if somebody can pin point the issue so in the next RMA I can advise HP Teleplan guys about it - they seem to not spend great deal of time researching the issue but try to do a quick fix that obviously didn't work.
Appreciate all your help !
PS - my System specs -
System Manufacturer/Model Number HP Pavilion Elite HPE-210F
OS Windows 7 Home Premium 64 Bit
CPU AMD Phenom(tm) II X4 945 Processor, 3000 Mhz, 4 Core
Motherboard H-RS880-uATX (Aloe)
Memory 8 GB PC3-10600 MB/sec (message as PC3-8500)
Graphics Card ATI Radeon HD 5450
Sound Card Integrated Realtec ALC888S Audio
Monitor(s) Displays Acer? H243H
Screen Resolution 1920 x 1080
Keyboard HP USB
Mouse Microsoft Compact Optical Mouse Model: 1016
PSU Bestec 300W
Case Mid-size ATX
Hard Drives Western Digital Caviar Green WD10EADS-65M28X
Internet Speed ATT DSL 6 MBPS
A:1st RMA completed - still random BSOD
Your dumps indicate conflicts and memory corruption. Uninstall Symantec using this removal tool: Tool. Many third party security programs create conflicts with Win 7 and Norton is no exception. Norton was involved in one of the crashes. Download and install Microsoft Security Essentials. It will not cause conflicts. Make sure Windows firewall is turned on.
Uninstall or upgrade CyberLink. Its driver, 000.fcl, Fri Sep 26 09:11:22 2008, is out of date. Outdated drivers can and do cause conflicts and BSOD's.
I find another slightly out of date driver loaded on your system. Update this driver from the link provided.
Quote:
usbfilter.sys Fri Apr 03 07:39:51 2009 - AMD USB Filter Driver (likely part of the chipset drivers). http://support.amd.com/us/Pages/AMDSupportHub.aspx. Update this driver.
Follow these suggestion, reboot and let's see if your system is more stable. Post back and let us know. If you get anohter BSOD, upload it and we will go from there.
Code:
Windows 7 Kernel Version 7600 MP (4 procs) Free x64
Product: WinNt, suite: TerminalServer SingleUserTS Personal
Built by: 7600.16385.amd64fre.win7_rtm.090713-1255
Machine Name:
Kernel base = 0xfffff80002804000 PsLoadedModuleList = 0xfffff80002a41e50
Debug session time: Thu Dec 16 09:41:31.624 2010 (GMT-5)
System Uptime: 0 days 8:53:11.013
...............................................................
8 more replies
I don't wish to bore you with things that may have nothing to do with the problem, but since I know very little about all this I may add too much. I apologize.
My HP Envy 15 started slowly acting odd and only typing totally backwards (weird) sometimes, then a lot. I figured it was directly related to an auto update that I never asked for. There were a few other things that I noticed that changed too, my laptop gradually started running slower and my fan was starting often when I would turn my laptop on.
I have been using a 10 upgrade since last year with no problems on my desktop computer and I updated my laptop from 7 PRO to 10 and started using it on this laptop this year with no problems.
What I didn't do was set a recover date. When my laptop was acting to weird for me I set it to go back to early April when I was not having issues. It was the earliest date it offered me, but it seemed to only add to my problems. I have had a number of issues with the right button on the touchpad, yet when I go to upgrade Synaptics, it tells me I have the latest available. Although it is not what I was using before the auto update. It would scroll backwards, and now I have no scrolling at all.
I do not want to keep trying to fix these issues myself when I am only guessing and I seem to be making things worse.
I REALLY look forward to any suggestions you could offer me.
Thank you so much for reading this far,
Sher
More replies
My computer must have received a new Windows 8 Update last night. This morning it asked me to reboot. After boot the keyboard and mouse do not work once Windows has booted. Also RDP results in a black screen and getting disconnected after a short while.
The keyboard and mouse work fine in BIOS, however as soon as Windows posts they disconnect. Prior to reboot, the keyboard and mouse were working fine. What doesn't make sense is that issue persists after both a system restore and a system image restore.
System - Dell XPS 8300 (3 years old). i5 - 2.8Ghz, 16 GB RAM, Windows 8 Pro (Downloaded via my tech net subscription)
What I've tried -
1. Different USB ports
2. System Restore
3. System Image Restore
4. Safe Mode - Still no keyboard, mouse, etc
5. Different keyboard / mouse
6. Remote Desktop (black screen) - Yes system was configured for RDP, logged in daily to it.
I don't get it. Keyboard and mouse work fine in BIOS and booting off of Windows DVD. This issues resulted after an update was applied. However doing a system image restore to over a week ago should have circumvented the update being applied.
At a loss. I work in IT, though haven't done desktop support in years. So maybe my skills are rusty, however I have never seen this issue before.
A:Windows Update last night, keyboard, mouse and RDP issues
I have same problem on 4 computers. This AM put an HP desktop back on line after a number of weeks off line (disconnected from all inputs).
Worked great (Windows 8.0) until I received notice updates were waiting. On completion and reboot, keyboard did does not respond after Windows takes control keyboard is inoperative. Items residing on desktop will not open after double click. Help,,,using a borrowed notebook w/Win 7 installed.
2 more replies
I have this problem were with my new 500Hz mouse the position of it takes ages to update on the desktop and only the desktop, not any other interface.
pcprob
See there, download the video if it won't play.
OS: Win 8 64 bit
CPU: AMD A4 4300M
RAM: 6GB (Dual Channel) 800 MHz
Any ideas?
EDIT: Also, when I move the mouse on thedesktop the CPU usage goes up to 50%! Any ideas? Explorer.EXE takes up all the CPU, no other programs do that.
More replies
After I downloaded and installed this update my labtec usb mouse has stopped
working. I also tried my generic wireless mouse and my other hp wireless mouse and
I would always come up with the same error.
Windows found driver software for your device but encountered an error while
attempting to install it.
USB Browser Mouse
An error occurred during the installation of the device.
The driver installation file for this device is missing a necessary entry.
This may be because the INF was written for Windows 95 or later. Contact your
hardware vendor.
If you know the manufacturer of your device, you can visit its website and
check the support section for driver software.
Is there anyway of removing the CHIC driver that windows update installed?
A:Solved: CHIC - Other Hardware - USB Browser Mouse Update
8 more replies
Hello all,
I installed the Creative X-Fi Audio Processor update (10/22/2009), and it completely messed up my computer (Windows 7 x64).
I accidentally installed this update while checking if I had new updates to install. Little did I know that it would cause me much grief. I rebooted the system so that the updates could finish, and when I saw my login screen things went bad. The screen resolution was all out of whack (800x600, while my regular resolution is 1920x1080). To make matters worse, the mouse won't move. When I logged in, I discovered the internet wouldn't work either. Soon, a popup window popped up, saying that "No ATI graphics driver is installed, or the ATI driver is not functioning properly. Please install the ATI driver appropriate for your ATI hardware." I went to the display settings (using only the keyboard) and discovered that my default resolution was no longer on the list. Dejected, I went on my other PC and downloaded the ATI driver pack for my video card on the crippled computer. I transfered it via flash drive to the crippled computer and installed it - rebooted, my resolution was back to normal, but the mouse and internet were still not working. I then transfered a Creative driver pack I got from the official site and put it on the flash drive and transferred it - no changes. I then used Guru3d's Driver Sweeper to get rid of the dregs of the Creative drivers, rebooted, nothing, and now my audio's dead too.
What's most depressing i... Read more
A:Creative Driver Update Messes Up Mouse and Internet
Hopefully, this may work
Repair Install[2]=General Tips
You should try to remove the update, also.
9 more replies
On a magazine recommendation I installed DriverMax. I ran it and selected one option to update a microsoft t selected installing an
updated mouse driver. I have win XP SP3. I also have a Microsoft
Wireless USB keyboard and mouse set.
What has happened is that the
wireless kb and mouse is now inoperative - but works during boot
sequence (I have an Asus P6TD mobo and can select pre-boot options for
this board via mouse. In fact NO USB mouse works after boot sequence is
complete).
The frustration I have is I cannot access the DriverMax program through the keyboard only commands because it only responds to mouse clicks. I had wanted to try to fix the errors by rolling back a driver within DriverMax because the program only allows mouse input and I cannot use any mouse... ANY help you can offer would be gratefully accepted.
I figure that the only way to proceed from here is to reinstall Windows XP? Having removed all kb and mouse drivers from the hardware list a couple of times; downloaded the latest Microsoft drivers/software for the usb wireless keyboard etc etc I cannot make a dent in the behaviour...This as you might guess is likely to be a pain in the proverbial to maintain all my software in working order and to re-upgrade to SP3.
A:usb Mouse & Keyboard non-functioning due to Drivermax 'update' of drivers
6 more replies
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2018-09-24 17:01:25
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http://www.gradesaver.com/textbooks/science/physics/fundamentals-of-physics-extended-10th-edition/chapter-2-motion-along-a-straight-line-problems-page-35/47a
|
## Fundamentals of Physics Extended (10th Edition)
Published by Wiley
# Chapter 2 - Motion Along a Straight Line - Problems: 47a
29.4m
#### Work Step by Step
The pipe strikes the ground at a speed of 24m/s. The acceleration due to gravity has a magnitude of $9.8m/s^2$. This means that each second, the velocity increases by 9.8m/s. Since the wrench was dropped, the initial velocity was 0m/s. We use the equation: $v =v0 + at$ Where v0 = initial velocity = 0 We get $24m/s = (9.8 m/s^2)t$ and solving for t we get t = 2.45 seconds Now that we have the time it took to reach the ground, we can use the equation $x = x0 +v0*t + (1/2)at^2$ This can be re-written as $\Delta x = v0*t +(1/2)at^2$ Once again, v0 = 0, $a = 9.81 m/s^2$ and we now know t = 2.45s Using all this information we have $\Delta x = 29.4m$
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.
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2017-06-25 01:42:36
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http://mathematica.stackexchange.com/tags/front-end/hot
|
# Tag Info
30
I implemented a multiple undo mechanism in v10. It's not as perfect as I would like it to be, yet, but it does a pretty decent job in my experience. And a few of the documented options for it got ahead of the implementation...think of some of that stuff as a "coming soon". Feel free to ping me on any problems you find with it.
22
This problem is probably due to the MathematicaMono font which is introduced in v10. Defining the problem: Some fonts ("[","_","]","=", etc.) are rendered badly with strange thinning in v10 in some notebook magnifications. This is obvious when you compare the renderings from v10 with those from v9. Analyzing the problem: I found that all of these ...
16
Mathematica still works with Courier by default. Nothing is broken about your copy of Mathematica. It is the case, however, that if you use any sans serif font (or at least any font that properly advertises itself as sans serif...many amateur font designers don't bother setting font metadata bits correctly), you'll see the new MathematicaSans font in use ...
14
This is not related to the output cell greying to indicate mismatch with the input cell. You can easily verify this by editing the input cell — it gets further greyed out. The new summarized display that is used for things like SparseArray, Interpolation, etc. has a setting "Interpretable" -> False. If this is the case, the output is showed in a gray ...
12
Based on Mr.Wizard's answer and Szabolc's comments to it, I now understand that the code I posted does have undesirable side-effects and it should be avoided. Specifically, the scoping constructs Module and Block are meant to completely localize the variables in their first argument (for more information see this question). However, placing their scoped ...
7
For file operations two workarounds currently work: 1) Use slash / instead of double backslash in the paths to files under Windows: Import["D:/test/кириллическое название/файл.txt"] 2) Use FileNameJoin or StringJoin: Import[FileNameJoin[{"D:", "test", "кириллическое название", "файл.txt"}]] Import[StringJoin[{"D:", "\\", "test", "\\", "кириллическое ...
6
I believe that highlighting is there specifically to encourage you to use DynamicModule rather than Module: DynamicModule[{A = 1}, Manipulate[Plot[A Sin[k x], {x, 0, 20}], {k, 1, 10}]] One reference: http://forums.wolfram.com/mathgroup/archive/2011/Sep/msg00198.html Also related: Table function with Part[] call misbehaving, but only after initial ...
6
This is a bug in Mathematica 10.0.0 and will be addressed in the first 10.0.x bug fix release (Mathematica 10.0.1). Thank you for reporting it and our apologies for any work lost because of this issue.
5
You need to set CellLabelAutoDelete->False You can do this programmatically: SetOptions[EvaluationNotebook[],CellLabelAutoDelete->False] or set it in your stylesheet.
5
Nothing is wrong with your settings. Mathematica 10 is supposed to be using the old fonts. The old fonts are shown in the blog post introducing Mathematica 10. Note: People report that the hack described below doesn't work on Windows or Linux. It works on OS X, where I tried it. But you can play with the new fonts if you like. Go to Format -> Edit ...
5
I analyzed which fonts are loaded when starting Mma v10 compared to v9. The problem could be tracked down to the loading of the fonts in the Folder $InstallationDirectory\SystemFiles\Fonts\TrueType If you open Mathematica-Bold.ttf or MathematicaMono-Bold.ttf, you will see how ugly these are. To prevent loading these fonts one should make a backup copy of ... 5 I was having kind of the same problem. I didn't had an error dialog like you and for me, the issue appeared when I rotated 3d graphics. When I did this, after a second or two, the notebook window grayed out too, although when I released the mouse button, everything turned back to normal. This seems to be a common problem and has to do with the ... 4 To give you a first idea: Try this button, which uses all currently selected cells in the selected notebook, copies them into a new document and evaluates everything Button["Test Selected Cells", NotebookEvaluate[CreateDocument[NotebookRead[SelectedNotebook[]]], InsertResults -> True], Method -> "Queued"] You can use this to create a new palette ... 4 In version 10.0 of Mathematica the main menu bar is gone, just as you want it. And each window has its own menu bar. 4 I think this is a bug rather than a feature. One way to accomplish this that will work in some scenarios without making a copy of the image is to use the crop tool, save the image and then undo the cropping thus restoring the original image. 4 This answer, which is a slight modification of my answer to a previous question, takes you most of the way there: Clear@notebookScreenshot notebookScreenshot[nb_] := Module[{left, top, size, opts = AbsoluteOptions@nb}, {left, top} = WindowMargins /. opts // Diagonal; size = WindowSize /. opts; Needs["GUIKit"]; ... 3 For the aid of anyone else who runs into this issue I seem to have figured out the compounding factors necessary to recreate this problem. Create a Windows directory C:\foo\bar Save arbitrary Notebook example.nb to this directory Using the Option Inspector add to NotebookPath exactly: "C:\\foo\\bar" Close and restart Mathematica Create a new Notebook and ... 3 You can use SyntaxInformation. In this case, SyntaxInformation[Lim] = {"ArgumentsPattern" -> {_, _, OptionsPattern[]}, "LocalVariables" -> {"Limit", {2}}} does what you want. 3 In Mathematica version 10, this now works on Mac OS X. For example, this rule is part of the system-supplied FontSubstitutions list: "Meridien" -> "Times" So when you type in the font name either incorrectly or if the system can't find a font with that name: Style["The quick brown fox", 80, FontFamily -> "Meridien"] you see the designated ... 3 Some front end troubles can be solved as described here: Troubleshooting On OS X holding down Shift-Command during startup will reset the caches. This is worth trying when the front end is misbehaving. When having multiple versions of Mathematica installed, some problems can be avoided by using separate configurations for the different front end ... 3 Use Remove aber = {1, 2, 3} Remove@aber 2 You can use MakeBoxes to format output pretty much however you like. This is what Mathematica does for InterpolatingFunction. You may be able to glean something by inspecting the output cell or from FormatValues[InterpolatingFunction]. Unlike InterpolatingFunction, I included an Interpretation, which means that the output in the notebook may be copied and ... 2 Most likely you merely set to some$FrontEnd options unintentionally. If you can figure out what these options are you can reset them by clicking the X next to the field in the Option Inspector: You can also select as text rather than by category to see a list of all the options that have been changed from the default (manually or otherwise).
2
Wireless keyboard/mouse adaptor may be a cause of a FE issue (there might be others I suppose). Removing it (at Wolfram's suggestion - credit for investigation so far) made MMA10 startup speed effectively normal & no "formatting notebook" popups were noted. Unfortunately I don't have a wired keyboard & mouse... [Setup i3, Win-7 pro 64-bit; all Acer ...
2
I was just working on something and here's a side effect. Nothing new but given in closed form as palette button: CreatePalette[ Button["Evaluate above", With[{NB = InputNotebook[]}, Do[ SelectionMove[ExperimentalFromCellIndex[NB, i], All, Cell]; SelectionEvaluate[NB]; , {i, 1, ExperimentalToCellIndex @ SelectedCells[NB][[1]]}] ]]] ...
2
The quotes appear because the InputForm does not show them, while the OutputForm does. Programmatically, you can explicitly call OutputForm to avoid this: Export["quotes.png", OutputForm[CharacterRange["a", "z"]]] You can also go into Format > Option inspector… and look for ShowStringCharacters and using Save selection as…:
2
Clear["Global*"] g[x_] := x^3 f1[x_] := g[x^2] f2[x_] := g[x^3] Definition@f1 f1[x_] := g[x^2] FullDefinition@f1 f1[x_] := g[x^2] g[x_] := x^3 Head@f1 Symbol Information["f*"] a[1] = 1; a[2] = 2; ?a DownValues@a UpValues@a
1
I'm on 10.0 for Mac OS X x86 (64-bit) (June 29, 2014) and and have the following observed: highlighting the Output-Cell and using the Command "Save Selection As" leads to the following result; highlighting the Output and using the Command "Save Selection As" leads to the observed result; Wile CellPrint[ExpressionCell[CharacterRange["a", ...
1
With V10 on OS X, I get Might be a platform issue.
1
It seems that the described method does work in v.10.0.0 if the image is represented as Graphics object. To convert Image to Graphics one can use Show. The reason why Graphics works is that the soft crop explicitly sets new PlotRange what can be seen by applying Options to the cropped image. But in the case of Image the PlotRange option exists only inside ...
Only top voted, non community-wiki answers of a minimum length are eligible
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2014-07-31 09:40:26
|
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https://www.physicsforums.com/threads/find-the-equation-of-a-tangent-line-at-each-given-point.949351/
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# Find the equation of a tangent line at each given point
in title
## Homework Equations
x=2cotθ
y=2sin2θ
dy/dx = 2sin3θcosθ
y-y1=m(x-x1)
point = (-2/√3,(3/2)
## The Attempt at a Solution
Have been stuck for hours
I solved for the dy/dx above, now I need to figure out how to get rid of the θ to get my equation in terms of x
so I was thinking sqrt(y/2) = sinθ and (x/2)*sinθ = cosθ
is this a correct approach?
Apparently ##\theta## is a parameter: ##x=x(\theta), y=y(\theta)##. Is that right? So you can write ##sin(\theta)=f(y), cos(\theta)=g(y)##. Then you eliminate ##\theta## and get ##x=x(y)## and ##\frac{dx}{dy}=h(y)##.
isukatphysics69
Orodruin
Staff Emeritus
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2022-05-27 18:32:14
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http://accesspediatrics.mhmedical.com/content.aspx?bookid=457§ionid=40092831
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Chapter 21
1. Indications
1. To obtain arterial blood for blood gas measurements.
1. When blood is needed and venous or capillary blood samples cannot be obtained.
2. Equipment. A 23- to 27-gauge scalp vein needle or a 23- to 25-gauge venipuncture needle (self-shielding safety type recommended), a 1- or 3-mL syringe, povidone-iodine and alcohol swabs, a 4 × 4 gauze pad, gloves, and 1:1000 heparin.
3. Procedure
1. For a blood gas sample, most hospitals already have 1-mL syringes coated with heparin. If this is not available, draw a small amount of heparin (concentration 1:1000) into the syringe to be used for submitting the blood gas sample and then discard the excess heparin from the syringe. The small amount of heparin coating the syringe is sufficient to prevent coagulation of the sample. Excessive heparin may interfere with laboratory results, causing a falsely low pH and PaCO2. If any other laboratory test is to be performed, do not use heparin.
1. The radial artery is the most frequently used puncture site and is described here. Alternative sites are the posterior tibial or the dorsalis pedis artery. Femoral arteries should be reserved for emergency situations. Brachial arteries should not be used because there is minimal collateral circulation and a risk of median nerve damage. Temporal arteries should not be used because of the high risk of neurologic complications.
1. Check for collateral circulation and patency of the ulnar artery by means of the Allen test. Elevate the arm and simultaneously occlude the radial and ulnar arteries at the wrist; rub the palm to cause blanching. Release pressure on the ulnar artery. If normal color returns in the palm in <10 s, adequate collateral circulation from the ulnar artery is present. If normal color does not return for >15 s or does not return at all, the collateral circulation is poor and it is best not to use the radial artery in this arm. The radial and ulnar arteries in the other arm should then be tested for collateral circulation.
1. Use of topical local anesthetic agents may diminish pain from arterial puncture. Oral sucrose given 2 min prior to the procedure (0.1–1.5 mL of a 24% solution depending on gestational age) and/or pacifier are preferred. (See Chapter 69.)
1. To obtain the sample, take the patient's hand in your left hand (for a right-handed operator) and extend the wrist. Hyperextension can occlude the vessel. Palpate the radial artery with the index finger of your left hand (Figure 21–1). Transillumination with a high-intensity fiberoptic light or marking the puncture site with a fingernail imprint may be helpful.
1. Clean the puncture site with a povidone-iodine swab (preferred for blood cultures) and then with an alcohol swab.
1. Puncture the skin at about a 30-degree angle, and slowly advance the needle with the bevel up until blood appears in the tubing (see Figure 21–1). With arterial blood samples, little aspiration is usually needed to fill the syringe. If there is no return of blood, withdraw the needle slowly because the artery may have been punctured through and through. Using the bevel down ...
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### AccessPediatrics Full Site: One-Year Subscription
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2017-02-26 21:18:57
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https://motls.blogspot.com/2018/02/bitcoin-scarce-cryptocurrencies-are.html?m=1
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## Friday, February 23, 2018
### Bitcoin, scarce cryptocurrencies are stocks in (hopeless) companies
The most adequate analogy should define the rules of taxation
Various central banks and regulators are trying to ban, suppress, or regulate the cryptocurrencies in one way or another. Others are preparing their own cryptocurrencies and join the irrational but widespread hype about the blockchain technology. Yet another group of central banks does both. The Polish central bank has paid some amusing $25,000 to Polish YouTube star to write texts and record videos such as I Lost All My Money about the cryptocurrency "investments". Czechia is the home to the largest non-Chinese and oldest Bitcoin mining pool, SlushPool, and there is a detectable important community that does these things. But cryptocurrencies remain a fringe phenomenon and that's also reflected by the attitudes of the Czech National Bank. Our central bank – typically echoing the views of Mojmír Hampl, the most active member of the board in such matters – says that it's right not to harm them, not to help them, not to protect them, and not to guide them by holding their little hands because they're irrelevant for the system and the Czech participants ultimately know what they're doing and that they enjoy no protection. The percentage of the wealth in the cryptocurrencies is very small and the percentage of the money in the real economy that goes through cryptocurrencies is even tinier. So the skeleton of our monetary system is in no way threatened. I agree it's true in Czechia but due to the ability of these bubble phenomena to rise exponentially, this assumption may very well break down in countries affected by a mania – such as South Korea. A repeating question is "what kind of an asset the Bitcoin and its volatile siblings are?". Are they currencies? Are they stocks? Derivatives? Commodities? Some pundits have pointed out that the Bitcoin buyers are like stamp collectors or the collectors of rare coins. The value is supposed to arise from the small number of copies that are out there. There aren't many people who own it and that's why it's a great idea to be one of them and pay lots of money for the stamps. Paying almost$10,000 for a Bitcoin – because there are just 17 million of them and the number won't ever surpass 21 million – follows a similar logic.
Well, the Czech National Bank has actually joined this interpretation, too. Bitcoin hodlers are a new generation of relatives of the collectors of stamps and rare coins, not to mention some crazier things (basketball trading cards) that people have been feverishly collecting. But stamp collectors are considered hobbyists. The purchases and sales of such things often take place in very informal circumstances and I believe that when the stamp collectors make some profit from a "complete cycle" of purchases and sales, most of them aren't taxing their profit at all. Am I wrong?
On top of that, there can't be any "truly complete" database of the kind of rare stamps and coins that you may own or be obsessed with. For those reasons, I think that the analogy between the Bitcoin and the stamps is misleading and unusable e.g. for taxation of the Bitcoin profits.
The Bitcoin is surely not a currency because it's not a trustworthy storage of value that could be effectively used as payments and compensation. One could say it's a commodity because the amount of a commodity is "roughly constant" and the price may vary rather dramatically. But the similarities between the Bitcoin and commodities such as metals are very limited: a chaotic graph and "approximate scarcity" are the only independent things they have in common.
At the end, I think that the Bitcoin totally falls to the category of a stock.
The only problem is that the company that you own produces zero profit and pays zero dividends. But you hold many ordinary stocks that also don't pay dividends for years and they have a value. You hold them because there are real assets behind the stock plus a hope that in the future, they will generate dividends again.
It's analogous with the Bitcoin. When you own a Bitcoin, you own one stock among 17 million in a company that just produces zero dividends (in dollars) and the rules indicate that it will always be so. But you pay for the stocks, anyway, because you believe that by being a shareholder, you possess some amazing invisible virtual assets. And sometimes in the future, the Bitcoins could produce dividends made out of unicorns.
When miners produce 12.5 new Bitcoins every 10 minutes in average, they are issuing new stocks. The key fact is that the total number of stocks in circulation is completely known and, in the Bitcoin case, perfectly planned. So the shareholders may use this perfectly well-known information to figure out what their investment is worth and whether they should buy or sell, reduce or accumulate.
The "miracle" of the Bitcoin and its approximate clones is the public-domain method to remember who owns which stocks. That's nice but sane investors don't really care about the precise method that remembers your balance in a database of the shareholders. A sane investor cares what he owns, not what is the shape of the paper or computer on which it's recorded that he owns it. The ordinary methods to remember and update the owners work just fine – the risk that they don't work doesn't significantly affect the stock prices. The Bitcoin hodlers are confused and they think that these details affect the price of the Bitcoin and that's how many of them explain why they bought into it.
But rational people know that this is just some irrational and emotional gibberish that pushes these people to do what they do. It doesn't matter at all what precise method is used to remember the ledger – and decide about the number of stocks that you currently own. Lawmakers and regulators should acknowledge the people's occasional irrational behavior and their right to behave irrationally but they shouldn't behave irrationally themselves.
The Bitcoin miners play the role of the managers of a company that is issuing new stocks because the decision to issue new stocks has been previously made by the shareholders' meeting. In 2009, Satoshi Nakamoto was the only shareholder of the Bitcoin stocks and he made the decision to issue new stocks according to the plan. Every 10 minutes, 50 new Bitcoins (stocks) were supposed to be issued in average. The number got halved in 2012 and 2016 and it does so once in four years.
What happens when there are $$N$$ stocks and you issue $$\Delta N$$ new stocks? Well, the total company (and its dividend profit, if any) was divided to $$N$$ stocks before the event but $$N+\Delta N$$ after the event. So rationally speaking, the price of the stock decreases by the factor of $$N/(N+\Delta N) \lt 1$$ at the moment when $$\Delta N$$ new stocks are issued. Because each old shareholder has a fixed number of stocks and their price goes down, his net worth goes down, too. The company gets new cash (dollars) by selling the newly printed stocks. The cash becomes an asset of the company and the total value of the company increases by the cash from the sale of new stocks during this operation – but after the new stocks are issued, it's divided among a larger number of shareholders. You expect these two effects to exactly cancel when it comes to the impact on the old investors' wealth. When new stocks are issued and sold, the company becomes more cash-like or diluted in cash but the value of the old investors' holdings is the same.
The increase of the number of stocks has indistinguishable real-world consequences from the following operation: At the shareholders' meeting, it may be decided that instead of issuing new stocks, all shareholders will sell the same fraction of their investment in the company. The fraction of his current stocks that he sells is equal to $$\Delta N / N$$. In both versions of the event, the ratio owned by the old and new shareholder is $$\Delta N:N$$. To make the operations really indistinguishable, you could clump the new stocks in the first case (or make a split in the second procedure) by the factor of $$N / (N+\Delta N)$$.
The Bitcoin "company" hires public folks with the mining hardware (GPU and ASICs) as their managers who physically issue the new Bitcoins (stocks). But the decision to actually issue them at some rate has been made by the shareholders – by those who hold the Bitcoins. It's expected that the rules will remain the same. But the miners, even though they're seemingly hired to do just some technical task whose basic purpose has been decided by shareholders, may actually "steal" the Bitcoins by performing a 51% attack. The Bitcoin holders have agreed to consider such a modification of the ledger to be legitimate. Even if they didn't, I think that no courts in the world would treat a 51% attack as an actual crime (shooting a monster in a computer game isn't a crime in "most" countries, either, and the 51% attack is formally just another thing you can do in a computer game). So it's the shareholders' risk. A lesson clearly is that the public blockchain method to update the database of shareholders makes it less safe, and not safer, for the shareholders than the old-fashioned methods where a thief may be held accountable and the theft may be reversed with the help of police and courts.
On top of that, the miners pocket all the money from the newly minted Bitcoins (most of this money is wasted for electricities and hardware). It's just like secretaries in a company who remember who bought the newly issued stocks and who pocket all the money collected from the sale of the new stocks! Imagine how stupid the shareholders would have to be to pay the secretaries this much. For some reason (I won't use the term "staggering idiocy"), the Bitcoin "shareholders" think it's a good deal. So far, most of the time, their bubble has been inflating so quickly that they haven't noticed what kind of an incredible waste of money they're doing on a daily basis.
At any rate, I think that the profit from the purchases and sales of the Bitcoin and similar cryptocurrencies should follow the precise recipes for capital gains from stocks. Things are simpler in the Bitcoin case because you may assume that the dividends will always be zero. But there may be capital gains and losses and those may be said to work as a special case of stocks.
It's funny to compare the Bitcoin to some actual companies. Take Kofola Czechoslovakia. It's sold for some CZK 411 ($20) now a piece. It's the producer of the legendary "Czechoslovak answer to Coke and Pepsi". Well, Kofola is special, it tastes significantly different, and some people may even hate it. But due to the retro spirit and people's habits, a bottle currently costs more than the same bottle of Coke! During communism, some research institute was ordered to find a useful application for some waste products during the production of coffee and they invented Kofola. After the fall of communism, the brand was resuscitated as a capitalist company by a skillful immigrant from Greece. One reason why Kofola is a particularly good company to be compared to the Bitcoin is that the total number of Kofola stocks is about 23 million, very close to the number of Bitcoins. So let's compare the Kofola Czechoslovakia company and the Bitcoin "company". They have both around 20 million stocks. The number is guaranteed not to grow, and if it does grow, the growth is controllable and has some advantages for the old stockholders (the company gets extra cash). A difference: Kofola produced dividends CZK 13.5 before taxation in the most recent year. The Bitcoin has produced zero. Kofola's market capitalization is some 9 billion crowns – less than half a billion dollars. It produces drinks that are considered a "cool brand" by some people from my generation in Czechoslovakia and the brand is considered worthless by many others. It sounds just like the Bitcoin. But there's still a difference: the Bitcoin hasn't produced a single bottle yet. It doesn't have any magic juice that some people may find tasteful or legitimately addictive. The Bitcoin "company" also produces zero iPhones, zero hamburgers, zero gallons of petrol, and zero of anything else, too. Nevertheless, while these are similar companies – with the difference that Kofola produces much more than the Bitcoin – and they have about the same number of stocks, the price of the Bitcoin is$10,000, about 500 times higher than the price of one Kofola stock. How is it possible that a drink producer Bitcoin that produces nothing compared to the nontrivial production by Kofola ends up costing 500 times more?
It's all about the brand and the irrational obsession of a sufficient number of people by the brand. Kofola is a good enough brand in some corners – as I said, you can sell lots of bottles for a higher price than the actual Coke. But the Bitcoin is a much more addictive brand. Even though those people get less than one droplet of their Bitcoin Kool-Aid, namely zero, they are still willing to pay 500 times more for a stock. In fact, it seems that the Bitcoin hodlers consider the "complete emptiness" of the Bitcoin to be a virtue, nor a vice. If you added a Kofola stock to every Bitcoin, the price of the Bitcoin wouldn't go up by $20. It could go towards zero, close to$20, because many people would realize that what they have actually is a Kofola stock and nothing more.
(The family of the late Greek Czech business has been accumulating the stocks to overtake the whole company again but some leftover of the stocks may still be traded at the Prague Stock Exchange. The stocks' performance at the Prague Stock Exchange has been a disappointment.)
The reason why I think that countries should classify Bitcoin-like cryptocurrencies as stocks (with zero dividend) is that stocks are the only well-known existing assets whose (high enough) price depends on the precise knowledge of the number (of stocks) that are out there. This is a property not shared by the fiat currencies (which may be printed and there are good reasons for that) and not even by commodities (metals may be mined and the mining may actually speed up if you pay to the drilling companies) or stamps (some number of rare stamps was printed and may be known but the number of those that have survived is smaller and unknown). On top of that, the Bitcoin forks have a counterpart in the stock splits (including splits of companies), too. The accounting rules are or may be isomorphic, and I think that the taxation rules should be the same, too.
If the cryptocurrency capital gains were taxed just like the stocks, there would be no need to invent anything new. Hodlers just need to learn how capital gains from stocks are taxed in one nation or another. (Weeks ago, I wrote a cool code in Mathematica to calculate my capital gains from individual stocks that were unusually positive in 2017. The broker doesn't provide us with these results itself and I believe that 99% of the traders must be unable to make the calculations that I have done.)
Of course, I tend to think that these recommendations come too late. The year when these people made some significantly taxable income was 2017 and it seems rather likely to me that all the following years will bring losses – and maybe the year 2018 will be the last one when this activity will exist at all.
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2018-06-22 05:38:11
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https://davidetorlo.it/publication/2021-06-15-relaxation-dec
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# Relaxation Deferred Correction Methods and their Applications to Residual Distribution Schemes
Published in arXiv, 2021
Recommended citation: R. Abgrall, E. Le Mélédo, P. Öffner and D. Torlo. (2021). "Relaxation Deferred Correction Methods and their Applications to Residual Distribution Schemes. " arXiv preprint, https://arxiv.org/abs/2106.05005. https://arxiv.org/abs/2106.05005
This is a work in collaboration with Rémi Abgrall, Elise Le Mélédo and Philipp Öffner.
In many models described by ordinary differential equations (ODEs) and partial differential equations (PDEs), there exists a scalar quantity that is physically conserved, e.g. energy, entropy, Liyapunov functional or angular momentum. Approximating with numerical methods the solutions of such models does not mean to automatically conserve these quantities. D. Ketcheson in Relaxation Runge-Kutta Methods: Conservation and stability for inner-product norms proposes a relaxation approach where each time step is relaxed by a factor $\gamma$. This means that the step that one actually does is a little more or a little less than the originally planned step. Properly tuning this $\gamma$, by solving a scalar (nonlinear) equation, one can guarantee to exactly conserve the desired quantity.
Without relaxationWith Relaxation
In this work, we extend the relaxation algorithm to the class of arbitrarily high order accurate schemes defined by the Deferred Correction methods, Dutt Minion Abgrall. These methods can be used as method of lines, and hence, rewritten into Runge–Kutta methods, but they can also be used as iteration methods to converge to complicated high order discretizations using matrix free schemes. In that context, the relaxation technique can be applied in different ways.
Convergence of Relaxed DeCPhase space evolution for a pendulum
Moreover, the whole procedure is limited by the necessity of having an entropy conservative/dissipative formulation of the spatial discretization, which fulfills the physical behavior of the solutions. We use the Entropy Fix approach by Abgrall, in the context of residual distribution to obtain either entropy conservative or entropy dissipative schemes.
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2022-05-26 10:08:56
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https://www.natureof3laws.co.in/tangent-galvanometer-class-12/
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# Tangent galvanometer class 12 – principle, construction, theory, and working
In this article, we will discuss the tangent galvanometer – principle, construction, theory, and its working, so let’s get started…
Inside Story
## What is tangent galvanometer?
Tangent Galvanometer – Tangent galvanometer is a device which is used to measure very small currents. It is a type of moving magnet galvanometer, and working is based on tangent law.
A tangent galvanometer is one of the first measuring instruments used to measure electric current. It works by using a compass needle to compare a magnetic field generated by the unknown current with the Earth’s magnetic field. It was first described by Johan Jakob Nervander in 1834.
## Principle of tangent galvanometer
A tangent galvanometer works on the principle of tangent law.
The magnetic needle of the galvanometer is subjected to the two perpendicular magnetic fields. One of these two perpendicular magnetic fields is due to the horizontal components of the earth’s magnetic field, and the other is due to the passing of the electric current through the coil of the tangent galvanometer.
Under the influence of these two magnetic fields, the needle comes to rest and makes angle $\theta$ with $B_H$, such that $B=B_H\tan\theta$
## Construction of tangent galvanometer
It consists of a circular frame of non-magnetic material mounted on the horizontal turntable. Three coils having 2, 50, 500 turns of insulated copper wire are wound on it. The ends of the coils are connected to the three base terminals.
A compass of non-magnetic materials is mounted in the center of the circular frame. It has a small center-pivot magnetic needle with a long, thin aluminum needle attached perpendicular to it.
Both are free to move on a horizontal circular scale graduated in degrees and divided into four quadrants of 0° – 90° each. A flat mirror is positioned at the base under the pointer. This removes errors due to parallax when reading pointer positioning.
• All nearby magnets and any other magnetic materials are removed away from the device.
• The tangent galvanometer is leveled with the help of leveling screws and the coil is so rotated that its plane becomes parallel to the length of the magnetic needle.
• In this position, the plane of the coil lies along the magnetic meridian.
• The compass box is rotated so that the pointer comes along the 0° – 0° line.
## Theory and working of tangent galvanometer
The working of the tangent galvanometer is based on the tangent law. When no current is flowing through the coil, the magnetic needle is only influenced by the horizontal component of the earth’s magnetic field $B_H$. When a current $I$ flows through the coil then it creates a magnetic field $B$ along the axis of the coil perpendicular to the $B_H$.
Now the magnetic needle is influenced by the two perpendicular magnetic fields, and hence the magnetic needle comes to rest at an angle $\theta$ with $B_H$ such that $B=B_H\tan\theta$. This relationship is called tangent law.
Now the magnetic field at the center of the coil is $$B=\frac{\mu_0 NI}{2R}$$ Where $N$ and $R$ are the numbers of turns and radius of the coil. $$\therefore\quad \frac{\mu_0 NI}{2R}=B_H\tan\theta$$ $$I=\frac{2R B_H\tan\theta}{\mu_0 N}=K\tan\theta$$ Where $K=\frac{2R B_H}{\mu_0 N}$ is a constant of the tangent galvanometer called reduction factor. $$\therefore \quad I\propto\tan\theta$$ Thus, in the tangent galvanometer current is directly proportional to the tangent of the angle of deflection of the needle. Due to this characteristic, the galvanometer is known as a tangent galvanometer. Knowing the value of $K$ and $\theta$ we can find the value of the current flowing through the coil.
## Sensitivity of the tangent galvanometer
The sensitivity of the tangent galvanometer is defined as the ratio of change in deflection of the needle to the current producing that deflection. $$\text{Sensitivity}=\frac{d\theta}{dI}$$ A galvanometer is said to be sensitive if it gives large deflection for small current.
$$\mathrm{I}=\mathrm{k} \tan \theta$$
Differentiating both sides w.r.t. $\theta$
\begin{aligned} &\frac{\mathrm{dI}}{\mathrm{d} \theta}=\mathrm{k} \sec ^{2} \theta \\ &\therefore \frac{\mathrm{d} \theta}{d I}=\frac{1}{\mathrm{k} \sec ^{2} \theta} \\ &\therefore \frac{\mathrm{d} \theta}{d I}=\frac{\cos ^{2} \theta}{\mathrm{k}} \\ &\text{but}\; \mathrm{k}=\left(\frac{2 \mathrm{R} \mathrm{B_H}}{\mu_0 \mathrm{n}}\right) \\ &\therefore \frac{\mathrm{d} \theta}{d I}=\frac{\cos ^{2} \theta}{\left(\frac{2 \mathrm{R} \mathrm{B_H}}{\mu_0 n}\right)} \\ &\therefore \frac{\mathrm{d} \theta}{d I}=\frac{\mu_0 \mathrm{n} \cos ^{2} \theta}{2 \mathrm{R} \mathrm{B}_{\text {H }}} \end{aligned}
Thus the sensitivity of the tangent galvanometer can be increased by
• Increasing the number of turns of the coils
• Keeping the value of $\cos^2\theta$ small
• Decreasing the value of the earth’s horizontal magnetic field. It can be done by placing an auxiliary bar magnet below the magnetic needle such that it opposes the horizontal component $B_H$.
• Decreasing the value of $R$ of the coil.
### Limitations in increasing sensitivity
• If the number of turns of the coil is increased then the radius of the coil will be not the same for all the turns. Radius will change because large numbers of turns lead to a thicker coil. But if the radius changes then the magnetic field at the center will also change.
• Increment in coil turns can increase the resistance of the coil of the tangent galvanometer.
• If the radius is made to be small then the magnetic field at the center will not be uniform.
• If $\theta$ decreases then accuracy will also decrease. Accuracy is maximum at $\theta = 45^{\circ}$.
## Accuracy of the tangent galvanometer
Let $d\theta$ be a small error in measuring the deflection $\theta$ so that the corresponding error in measuring the current $I$ is $dI$, then
$$\begin{array} \quad \mathrm{I}=\mathrm{K} \tan \theta \ldots \ldots \ldots .(1) \\ \text { Differentiating both sides w.r.t. } \theta \\ \frac{\mathrm{dI}}{\mathrm{d} \theta}=\mathrm{K} \mathrm{sec}^{2} \theta \\ \therefore \quad \mathrm{dI}=\mathrm{K} \mathrm{sec}{ }^{2} \theta \cdot \mathrm{d} \theta \ldots \ldots .(2) \\ \text { Dividing equation (2) by (1) } \\ \therefore \frac{\mathrm{d} \mathrm{I}}{I}=\frac{k \cdot \sec ^{2} \theta \cdot \mathrm{d} \theta}{K \cdot \tan \theta} \frac{\mathrm{d} \theta}{\cos ^{2} \theta \cdot \frac{\sin \theta}{\cos \theta}} \\ \therefore \quad \frac{\mathrm{dI}}{I}=\frac{\mathrm{d} \theta}{\cos \theta \cdot \sin \theta}=\frac{2 \mathrm{~d} \theta}{2 \cos \theta \cdot \sin \theta} \\ \therefore \quad \frac{\mathrm{dI}}{I}=\frac{2 \mathrm{~d} \theta}{\sin 2 \theta} \end{array}$$
Now, here you can see that the accuracy is maximum when the error is minimum i.e the value of $dI/I$ is minimum. i.e the value of $\sin2\theta$ is maximum. See below: \begin{aligned} &\sin2\theta =1\\ &\therefore\; 2\theta = \sin^{-1}(1)\\ &2\theta =90^{\circ}\\&\therefore\;\theta =45^{\circ} \end{aligned} Thus, the accuracy of tangent galvanometer is maximum at 45°.
Stay tuned with Laws Of Nature for more useful and interesting content.
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2023-03-21 03:46:54
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https://kluedo.ub.uni-kl.de/frontdoor/index/index/year/2004/docId/1468
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## Wavelet Modelling of the Spherical Inverse Source Problem with Application to Geomagnetism
• The article is concerned with the modelling of ionospheric current systems from induced magnetic fields measured by satellites in a multiscale framework. Scaling functions and wavelets are used to realize a multiscale analysis of the function spaces under consideration and to establish a multiscale regularization procedure for the inversion of the considered vectorial operator equation. Based on the knowledge of the singular system a regularization technique in terms of certain product kernels and corresponding convolutions can be formed. In order to reconstruct ionospheric current systems from satellite magnetic field data, an inversion of the Biot-Savart's law in terms of multiscale regularization is derived. The corresponding operator is formulated and the singular values are calculated. The method is tested on real magnetic field data of the satellite CHAMP and the proposed satellite mission SWARM.
$Rev: 13581$
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2015-07-04 13:58:57
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https://tongfamily.com/2015/03/31/learning-swift-and-the-best-of-both-worlds-play/
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Well, having suffered through Objective C and liked XCode compiler, it has sure been interesting to see what Apple has come up next with Swift. It's the brain child of Chris Lattner. He's had a pretty incredible career, developing LLVM (a compiler backend) and then Clang (a front end) and finally XCode that's been used for Apple's development tools.
The Swift uses LLVM and runs in the same environment as Objective C, but has scripting like constructs built in as well as being strongly typed, so it is in the middle ground between scripting simplicity and the power of C. The iBook is actually a pretty good description of everything that it can do with native support for sequences, lists, ranges, it is pretty neat. If we were doing a marketingplaybook.com essay, it would be about how Swift is the best of compiled and interpreted languages:
• It has the really nice abbreviated syntax of a Python but has the strict type checking of Objective C (sometime even more so)
• It has the power of classes and because it uses the LLVM backend, you can mix and match it with Objective C
And Playgrounds let's you make changes and insert code and see what is happening on the right pane. Pretty cool because Swift incrementally compiles so it really is the best of both worlds.
Others are doing the same thing with Google Go and Facebook Hack, so there's so much more for programmers to learn. How fun is that!
Check this out for coolness where a data structure as a series of sequences and dictionaries and this looks at all the numbers in the sequences to find the largest number:
let? ?interestingNumbers? = [ ? ?"Prime"?: [?2?, ?3?, ?5?, ?7?, ?11?, ?13?], ? ?"Fibonacci"?: [?1?, ?1?, ?2?, ?3?, ?5?, ?8?], ? ?"Square"?: [?1?, ?4?, ?9?, ?16?, ?25?], ?] ?var? ?largest? = ?0 ?for? (?kind?, ?numbers?) ?in? ?interestingNumbers? { ? ?for? ?number? ?in? ?numbers? { ? ?if? ?number? > ?largest? { ? ?largest? = ?number ? } ? } ?} ?largest
Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. https://itun.es/us/jEUH0.l
This thing definitely has it's subtleties, for instance the use of question mark to say that the variable may have a legitmate value or a nil is pretty cool but different syntax. Touch-magazine explains it pretty well though.
First there is this cool idea of a data type type that applies to all types, so this means you can make any type Optional:
enum Optional : NilLiteralConvertible { case None case Some(T) }
This interesting syntax means that there are two cases, with a nil for case and then Some(T) means just return the type. So it allows something like OptionalInt which says it can be a nil or an integer value. So that Int? just maps to Optional<Int>
There is a different use of the question mark, where it is syntactic sugar that says if the object is a nil then don't execute it. Finally, there is the ability to cast things as needed, so there is both "upcasting" and "downcasting", so you there is this idiom that says takes something and cast it down to its more basic component. For instance, if a string is an object, then the "if let" gives you a nice temporary constant to refer to it as that "downcast" item.
var str : String if let object=str is NSObject { println("I'm an object at my core") }
Similarly you can upcast something, so for instance with the as? it means that if you can see if it is the higher level object or through a forced conversion
var floatValue : Float if let intValue=floatValue as? Int {
println("I can treat this object (floatValue) as a integer (intValue)by a forced cast which cuts off the decimal part for now")
}
Some other amazing things about it are the way it uses closures to supply functions to things. That's incredibly useful and concise. For instance, to supply a sort function, instead of having to send it a pointer to a function in C, you just give it some code as an argument. The syntax is interesting, the function isOrderedBefore takes two types and returns a boolean, if it is a closure, you don't parentheses to enclose it. Also closures like this can use $0,$1 like shell scripts so you don't have to name the incoming arguments:
// function definition mutating func sort(isOrderedBefore: (T, T) -> Bool) // usage var array = [ 5, 3, 2, 7 ] array.sort { $0 <$1 }
### Map/Reduce
It also directly supports the Hadoop style map/reduce where map basically does things in parallel and reduce takes an entire array and turns it into a single number
// definition says, you map with type U and you supply a transform which takes as an argument any type T and returns the type U, the map itself returns something of type U func map(transform: (T) -> U) -> [U] //usage var array = [ "Brick", "Bar", "Yellow" ] let found = array.map { $0 == "Brick" } println(found) // Should return [ true, false, false ] // definition of reduce looking for any trues in the string func reduce(initial: U, combine: (U, T) -> U) -> U // usage is a little strange, the first argument is enclosed in parentheses, but the closure is out of the parentheses let inArrayAtAll = found.reduce(false) {$0 || \$1 }
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2022-08-10 17:29:48
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https://math.stackexchange.com/questions/942302/simplex-m-method-minimization-problem
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# simplex M-method minimization problem
Solve using the simplex method. Identify the solution of the dual in the final simplex tableau Minimize: $$z=12x_{1}+4x_{2}+2x_{3}$$ **Constraints:**$$x_{i}\ge 0$$ $$-6x_{1}+3x_{2}\ge 9$$ $$2x_{1}-2x_{2}-6x_{3}\le -4$$
so first I turned the problem into a maximization by multiplying z by -1 and all of the coefficients on the right hand side of my constraints must be non negative so I multiplied the 3rd constraint by -1
Maximize: $$z=-12x_{1}+-4x_{2}-2x_{3}$$ **Constraints:**$$x_{i}\ge 0$$ $$-6x_{1}+3x_{2}\ge 9$$ $$-2x_{1}+2x_{2}+6x_{3}\ge 4$$
then I changed all inequalities into equations by adding surplus and artificial variables and added the new variables to the objective function
Maximize: $$z=-12x_{1}+-4x_{2}-2x_{3}+0x_4-Mx_5+0x_6-Mx_7$$ **Constraints:**$$-6x_{1}+3x_{2}-x_4+x_5= 9$$ $$-2x_{1}+2x_{2}+6x_{3}-x_6+x_7=4$$
then I constructed my tableau, sorry for the formatting there doesn't seem to be a good way to set up tableau
$$x_1\; x_2\; x_3\; x_4\; x_5\; x_6\; x_7$$ $$12 \; 4 \; 2 \; 0 \; M \; 0 \; M$$ $$x_7\; -M\; -2\; 2\; 6\; 0\; 0\; -1\; 1\; 4$$ $$x_5 \; -M \; -6 \; 3 \; 0 \; -1 \; 1 \; 0\; 0\; 9$$ $$12+8M\; 4-5M\; 2-6M\; -M\; 0\; M\; 0\; -13M$$
I get a little confused trying to find my pivot column with the M's but using the fact the M is a large positive number I supplemented 1000 for each M and determined the 2-6M must be the most negative value in the last row making $x_3$ my pivot column
then dividing the coefficients of the last row by the coefficients of the pivot column i determined that the smallest $9/0 = 0 \; \; \;4/6=2/3$ so $x_7$ must be my pivot row and 6 is my pivot
Then I created my new tableau by dividing the pivot row by the pivot, leaving $x_5$ unchanged since the coefficient is already 0 and (-2+6M)(new $x_3$ row) and adding it to the last row to make my new last row $$x_1\; x_2\; x_3\; x_4\; x_5\; x_6\; x_7$$ $$x_5\; -6\; 3\; 0\; -1\; 1\; 0\; 0\; 9$$ $$x_3\; \frac{-1}{3}\; \frac13\; 1\; 0\; 0\; \frac{-1}{6}\; \frac16\; \frac23$$ $$(\frac{38}{3}+6M) \; (\frac{34}{3} +10M)\; 0\; -M\; 0\; \frac 13 \; (\frac{-1}{3}+M)\; (\frac{-4}{3}-9M)$$
Now obviously there is still a negative in my last row with -M in $x_4$ so this should be my new pivot column but to find the pivot row one coefficient is -1 and one 0. I can't use a negative and I don't think I can use 0 since then my entire pivot row would be divided by 0 so I am stuck.
This would lead me to believing no solution but the problem makes it seem like there should be a solution. What am I doing wrong? And what does it mean by find the solution of the dual?
Using the Maple I am obtaining
$$[ 12.0,[x_{{1}}= 0.0,x_{{2}}= 3.0,x_{{3}}= 0.0]]$$
Using Z3opt I am obtaining the same result
(+ (* 12 x1) (* 4 x2) (* 2 x3)) |-> 12
sat
(model
(define-fun x3 () Int 0)
(define-fun x2 () Int 3)
(define-fun x1 () Int 0)
)
Please run the code online here
• thank you for figuring that out. I'm still not sure how to get there tho using tabeau's by hand. Any ideas what i'm doing wrong? – Mikky Davey Sep 23 '14 at 2:22
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2020-01-18 11:50:58
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https://questions.examside.com/past-years/jee/question/pthe-time-period-of-a-satellite-revolving-around-earth-in-jee-main-physics-motion-x9jglxzovzfnrayd
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1
JEE Main 2022 (Online) 29th June Evening Shift
+4
-1
The time period of a satellite revolving around earth in a given orbit is 7 hours. If the radius of orbit is increased to three times its previous value, then approximate new time period of the satellite will be
A
40 hours
B
36 hours
C
30 hours
D
25 hours
2
JEE Main 2022 (Online) 29th June Morning Shift
+4
-1
The escape velocity of a body on a planet 'A' is 12 kms$$-$$1. The escape velocity of the body on another planet 'B', whose density is four times and radius is half of the planet 'A', is :
A
12 kms$$-$$1
B
24 kms$$-$$1
C
36 kms$$-$$1
D
6 kms$$-$$1
3
JEE Main 2022 (Online) 28th June Evening Shift
+4
-1
Water falls from a 40 m high dam at the rate of 9 $$\times$$ 104 kg per hour. Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydroelectric energy number of 100 W lamps, that can be lit, is :
(Take g = 10 ms$$-$$2)
A
25
B
50
C
100
D
18
4
JEE Main 2022 (Online) 28th June Evening Shift
+4
-1
Two objects of equal masses placed at certain distance from each other attracts each other with a force of F. If one-third mass of one object is transferred to the other object, then the new force will be :
A
$${2 \over 9}$$ F
B
$${16 \over 9}$$ F
C
$${8 \over 9}$$ F
D
F
JEE Main Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
EXAM MAP
Joint Entrance Examination
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2023-03-27 10:58:03
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http://instal.bialystok.pl/bible-verses-rpwa/resident-evil-4-chapter-2-1-2049f1
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# resident evil 4 chapter 2 1
Theory: Water hardness may be defined as the content of dissolved magnesium, calcium salts and also several other elements from the Mendeleev periodic table. Are glass office partition walls cheaper than bricks? Let the burette reading of EDTA be V 3 ml. 2. Prices starting from $3 per page for your Homework Writing Help. A sample of the waterbuffered at pH 10is titrated with a standard solutionof EDTA. EXPERIMENT 7: QUANTITATIVE DETERMINATION OF TOTAL HARDNESS IN DRINKING WATER BY COMPLEXOMETRIC EDTA TITRATION Chemistry 26.1 Elementary Quantitative Inorganic Analysis. The procedure de-scribed affords a means of rapid analysis. Calculation 1 ml of 0.01 M EDTA ≡ 1 mg of CaCO 3 V 1 ml of EDTA ≡ V 1 mg of CaCO 3 Calculation of total hardness Volume of EDTA solution consumed = ………… ml Volume of hard water taken = …………. EXPERIMENT 1: HARDNESS OF WATER BY EDTA TITRATION INTRODUCTION Water ‘hardness’ is a measure of the amount of hard water cations in water. Academic year. 2. Simple Water … Select the titrant. Let the burette reading of EDTA be V 2 ml. The video for the calculation of total hardness of water is given below. Then calculate the hardness of water sample in ppm using the equation … But EDTA has a stronger affinity towards Ca++ and Mg++. You must have heard about hard water problem of Noida. result calculation. Pipet 50 mL portions of unknown water into three 250 mL Erlenmeyer flasks. �L,���#?w\6�4�۟������B�M��7 ~�}U.�����ј���в���dN��4��&kll�Sf!s3����WYm�����)���6dA;�!}��Y��1�? 3. As practice, we will titrate an unknown bottled water and report the water hardness as ppm CaCO3. … However, above pH 10 there is a danger of precipitation of CaCO3 and Mg(OH)2. EDTA titration for the determination of water hardness using murexide and Eriochrome black T as indicators. What are the various tests done in environmental engineering lab? Hardness that is removed by this process is referred to as temporary hardness while that which remains after boiling is called permanent hardness. Let the burette reading of EDTA be V 3 ml. This method is based on Method 2340 C of Standard Methods for the Examination of Water … e����π �L@Q��v���00/e��h����j��i) ��2��0��y���)�m@��R������y�p~x-�pY �R���Ex�4#�17��t�Q � �� endstream endobj 28 0 obj<> endobj 29 0 obj<> endobj 30 0 obj<>stream Titrate with EDTA until a blue color appears. @sw��lcH�oL}k�z(7Yq?�I�x��j �za�z�I7��|��P!�I$1'?L'���W���P1%߂SJ��ָE�U�mʊL�l�/�jm���6�O��V?̙V��߳�>g0��c�l��w�. Read More: How to reduces the hardness of water? Read about EDTA and its titration on pp. Complexometric titrations with EDTA have been reported for the analysis of nearly all metal ions. B = mg CaCO3 equivalent to 1 ml EDTA Titrant. The reaction between EDTA and all metal ions is 1 mol to 1 mol.Calculate the molarity of the EDTA solution. EXPERIMENT 1: HARDNESS OF WATER BY EDTA TITRATION INTRODUCTION Water ‘hardness’ is a measure of the amount of hard water cations in water. 258 DETERMINATION OF HARDNESS IN A WATER SAMPLE. Water ‘hardness’ is a measure of the amount of hard water cations in water. Determination of Hardness of Water by EDTA Method Video Lecture from Water Chapter of Applied Chemistry I Subject for all engineering students. The calculation of hardness in water by EDTA titration can be found by adding a small amount of a dye such as Erichrome Black T is added to an aqueous solution containing Ca++ and Mg++ ions at a pH of 10 ± 0.1, Ca++ and Mg++ form chelated complexes of wine red colour with EBT. Students also viewed. EDTA Titration for Determination of calcium and magnesium. Determination of water hardness by EDTA titration. (5 Pts.) Calculate titration curves for the titration of 50.0 mL of $$5.00 \times 10^{-3}$$ M Cd 2 + with 0.0100 M EDTA (a) at a pH of 10 and (b) at a pH of 7. These procedures were more rapid than the conventional gravimetric methods (P), which … The concentration of Ca2+ ions is usually expressed as ppm CaCO 3 in the water sample. Complexometric Titration with EDTA B. As water hardness is usually reported in terms of mg/L of calcium carbonate (even if water contains both calcium and magnesium), we will use for calculations slightly strange reaction equation: CaCO3 + EDTA4- → CaEDTA2- + CO32- That allows direct calculation of calcium carbonate mass for known amount of titrant used. Nitrogen Content Present in Water-Quality Parameters, Determination of the Turbidity of Water-Environmental Engg Lab, Determination of Dissolved oxygen content in water, Determination of Optimum Coagulant Content in Water by JAR TEST, Determination of Alkalinity of Water-EE Lab, Determination of Acidity of Water Sample-Test on Water Quality, Determination of Electrical Conductivity of Water, Determination of pH (potentia Hydrogen) of water, Determination of Solids in Water-Total Solids,Fixed and Suspended Solids. 27 0 obj <> endobj 55 0 obj<<1AAEDBD885A011DD89CE0017F2059850>]/Info 26 0 R/Filter/FlateDecode/W[1 2 1]/Index[27 47]/DecodeParms<>/Size 74/Prev 43362/Type/XRef>>stream Calculate The Number Of Moles Of CaCO3 In The Water. However, the complexation constant is a function of pH (Harris, 1999). Can we construct a retaining wall without weep holes? EDTA … Theory: Will be measuring hardiness and calculate in ppm. EDTA Determination of Total Calcium and Determination of Individual Calcium and Magnesium. Objective Apply the concept of complexometric titration in the determination of total hardness in drinking water 3. Objective This lab will introduce you to the concept of complexometric titrations. This reagent is a weak acid that can lose four protons on complete … These procedures were more rapid than the conventional gravimetric methods (P), which involve time-consuming precipitations and separa-tions. Choose the indicator & start the titration. The sample is diluted with distilled water to reduce the concentration of Ca++ and Mg++ ions. Sodium in very large quantities may behave like a hardness producing ion due to common ion effect. Report the water hardness … For the titration … (5 Pts.) Equations: Titration… Advantages of EDTA method This method is definitly preferable to the other methods, because of : (i) Greater accuracy, (ii) convenience and (iii) more rapid procedure. Objective Apply the concept of complexometric titration in the determination of total hardness in drinking water 3. Complexometric Titration using EDTA. 3. The Determination of Water Hardness and Water Filtration Things for the lab notebook and to be included in the lab report: 1. In the EDTA titration, it is assumed that the total hardness is due to the presence mainly of calcium and magnesium ions. View ATQ5.docx from ENG MISC at University of the Philippines Los Baños. Buffer solution preserve pH at a balanced position. The formation of a particular class of coordination compounds, called chelates, are especially well suited for quantitative methods. chemical structure for the disodium salt of EDTA is shown in Figure 22-1. Determination of the Hardness of Tap Water 1. The manual-visual endpoint detection method, however, has given some difficulty. In the EDTA titration, it is assumed that the total hardness is due to the presence mainly of calcium and magnesium ions. In most water samples, calcium and magnesium are the chief contributors to water hardness. - 2. Question: DETERMINATION AND REMOVAL OF HARDNESS OF WATER Determination Of Hardness Of Water / Titration With EDTA Solution: Determine The Volume Of EDTA Solution Used. 2. Add 5 mL of pH 10 buffer, 2 drops of Eriochrome Black T indicator, and 15 drops of 0.03 M MgCl2. Adjust the molarity of titrant. Background. Calcium and magnesium are easily measured by titration with the complexing agent ethylene-diaminetetraacetate … )”or “hardness (EDTA).” 2340 B. Hardness by Calculation 1. Water hardness is measured in parts per million or milligrams per liter. 2. Write the equation for the titration of Ca+2 with EDTA. Compare your results with Figure $$\PageIndex{3}$$ and comment on the effect of pH on the titration of Cd 2 + with EDTA… Hence, if EDTA is added the former complex (Ca-EBT and Mg-EBT)is broken and new complex (Ca-EDTA and Mg-EDTA) of blue colour is formed. Helpful? These, combined with the dissociated carboxyl groups, create a 1:1 hexadentate complex with each divalent ion in solution. Experiment 7 2. Sample Calculations (Cont.) Please sign in or register to post comments. In this method buffer solution is used for attain suitable condition i.e pH level above 9 for the titration. Experiment 4: Determination of Water Hardness Purpose: In this experiment we will be calculating the total hardness, expressed as ppm CaCO 3, in a sample of water, and also calculate the hardness due to magnesium ions and calcium ions separately. Quantitative Analysis Laboratory. Calculation of total, permanent and temporary hardness. Answer Mol arity EDTA (m ol / L) = Volume Zinc ( L)× Mol rity m l / × 1 mol EDTA … All All mass measurements were taken from a AND Balance, serial number 12321601 and all titrations were done using a KIMAX buret, #173. QUANTITATIVE DETERMINATION OF TOTAL HARDNESS IN DRINKING WATER BY COMPLEXOMETRIC TITRATION R. ASCAÑO, J.J. CLEMENTE AND S.M.D. Take a sample volume of 20ml (V ml). Let the burette reading of EDTA be V 2 ml. 310-318; 325-328; 853e in your text. The presence in water of salts of calcium and magnesium is spoken of as hardness. Portland State University. Titrate with EDTA solution till the color changes to blue. Hardness by EDTA Titration METHOD SUMMARY This SOP describes the procedure for measuring hardness by titration with standard EDTA solution to endpoint indicated by a color change. Calculate The Molarity Of CaCO3 In The Water. Determination of Mg by Titration with EDTA INTRODUCTION: Many metal ions react with electron pair donors to form coordination compounds or complex ions. Quantitative Determination of Total Hardness in Drinking Water by Complexometric EDTA Titration 1. When colour changes from wine red to blue click the "stop" button & note the volume of EDTA used. This standardized EDTA solution is then used to determine water "hardness" – the total calcium and magnesium content, typically expressed as equivalent calcium carbonate mass concentration. In aqueous solution edta … Estimation of hardness of water by EDTA method. Determination of Permanent hardness Take 100 ml of sample hard water … 2016/2017. The optimum pH for the determination of hardness of water is 10.0 + 0.1 and is adjusted by NH4 OH – NH4Cl buffer. )”or “hardness (EDTA).” 2340 B. Hardness by Calculation 1. ���&k���8�( )D��d ��!����QtI��d,f If you want to know estimation of hardness present in water then complexometric titration is an easy, safe and cost-effective method to do so. In most water samples, calcium and magnesium are the chief contributors to water hardness. Apparatus for hardness of water experiment, Reagents for hardness of water experiment. View Det Water Hardness by EDTA Titration Calculations from CHEM CHEM 103 at Northeastern Illinois University. Dilute 25.00 mL of unknown zinc sample to 250 mL with distilled water in a volumetric flask. Ras Danny• 1 year ago. Both the total hardness and the individual calcium and magnesium hardnesses will be measured. Determination of the hardness of an unknown bottled water. B = mg CaCO3 equivalent to 1 ml EDTA … CHUNGUNCO1 AND J.R.N. moles M 2+ = moles EDTA used in titration moles M 2+ = c(EDTA) x V (av) x 10-3 mol Concentration of M 2+ in hard water: concentration M 2+ = moles M 2+ ÷ volume of water sample (L) moles M 2+ = c(EDTA) x V (av) x 10-3 mol volume of hard water … Select a definite volume of water sample. Record the titration volumes. The mean corrected titration volume of the EDTA solution was 16.25 mL (0.01625 L). In most water samples, calcium and magnesium are the chief contributors to water hardness. Water hardness can be readily determined by titration with the chelating agent EDTA (ethylenediaminetetraacetic acid). Hardness by EDTA Titration METHOD SUMMARY This SOP describes the procedure for measuring hardness by titration with standard EDTA solution to endpoint indicated by a color change. To determine the total hardness of the given samples by EDTA titrimetric method. State the value to 5 places after the decimal point. Determination of Hardness of Water by EDTA Titration/Complexometric Titration As Ca++ and Mg++ ions are present in significant qualities in water hardness is generally attributed to their presence. Why do we use a temperature bar in a slab? EDTA reacts quantitatively with both calcium and magnesium ions in a 1:1 stoichiometric ratio. 3. Determination of Hardness of Water by EDTA Titrimetric Method. A chelate is formed when a metal ion coordinates with two (or more) donor groups of a single ligand. Titrate the solution with EDTA from your buret to the blue endpoint you observed when titrating the blank. Determining the moles of Ca 2+ and Mg 2+ by titration with EDTA … Hardness of water is a measure of its capacity to precipitate soap, and is caused by the presence of divalent cations of mainly Calcium and Magnesium. Problem-solving. The primary cations causing hardness are calcium, magnesium, strontium, ferrous ion, and manganous ions.The common anions that combine with these cations to cause hardness are bicarbonates, sulphates, chloride, nitrate and silicate. - 2. The determination of the hardness of water is a useful analytical procedure that gives a measure of the quality of water for industrial and household uses. When reporting hardness, state the method used, for example, “hardness (calc. CLARO NATIONAL INSTITUTE OF GEOLOGICAL SCIENCES, COLLEGE OF SCIENCE UNIVERSITY OF THE PHILIPPINES, DILIMAN, QUEZON CITY, PHILIPPINES DATE SUBMITTED: MAY 9, 2013 ABSTRACT Calcium and magnesium ions’ ability to to … QUANTITATIVE DETERMINATION OF TOTAL HARDNESS IN DRINKING WATER BY COMPLEXOMETRIC EDTA TITRATION R.A. ROGIO DEPARTMENT OF MINING, METALLURGICAL AND MATERIALS ENGINEERING, COLLEGE OF ENGINEERING UNIVERSITY OF THE PHILIPPINES, DILIMAN QUEZON CITY, PHILIPPINES DATE PERFORMED: JANUARY 31, 2013 INSTRUCTOR’S NAME: MS. MELANIE BUCSIT Complexometric EDTA titration … Hardness EDTA as mg/L CaCO3 = (A*B*1000)/(ml of Sample) Where: A = ml EDTA Solution Used. Calcium and magnesium are easily measured by titration … Note the lone pairs of electrons on the two nitrogens. x�bbdb�$���f ��$8� �*�H�l@�\�Dx �&�^V�)� V=�� Hardness may be present from zero to several hundred mg/L as CaCO3. Determination of Total hardness Repeat the above titration method for sample hard water instead of standard hard water. … EDTA titration for the determination of water hardness using murexide and Eriochrome black T as indicators. When colour changes from wine red to blue click the "stop" button & note the volume of EDTA used. Write the equations for the endpoint color change of Eriochrome Black T (EBT) with Mg+2 3. University. 3. Method C, the EDTA titration method, measures the calcium and magnesium ions and may be applied with appro- priate modification to any kind of water. Add 6 drops of indicator and 3 mL of buffer solution. These hard water cations include calcium, magnesium, iron, zinc and the other polyvalent metal ions. Determine the unknown calcium concentration in a sample of water. Quantitative Determination of Total Hardness in Drinking Water by Complexometric EDTA Titration 1. In the lab 1 ppm CaCO 3 is expressed as 1 mg CaCO 3 per 1 Liter of sample or ppm … Originally, the hardness of water was understood to be a … To each flask add 6 drops of the indicator and 5 mL of pH 10 buffer solution. Equations: Titration: Ca2+ + H 2Y2-→ CaY2-+ 2 H+ Simple Water and Complexes 4. Experiment 7 2. Hardness of water is a measure of its capacity to precipitate soap, and is caused by the presence of divalent cations of mainly Calcium and Magnesium. This is the endpoint of the titration. �&5�0�8�P���L�3\SQ�Q��b�E"�pq���|�{��,�&FA0��� x09�(�L"fBS�P�T �j��u�n�~��uYM������ZZ �a�- Abstract: Complexometric titration was used to determine the water hardness of an unknown sample. In this article, we are going to talk about the determination of hardness of water by EDTA titration method.The causes of hardness of water is by multivalent metallic cations, which react with soap to form precipitates and with certain anions present in water to form scale. QUANTITATIVE DETERMINATION OF TOTAL HARDNESS IN DRINKING WATER BY COMPLEXOMETRIC EDTA TITRATION G.M.L. Determination of Water Hardness using Complexometric titration You will use EDTA complexometric titration to determine the hardness of a sample of water brought from your home. Write the equation for the titration of Ca+2 with EDTA. The corrected titration volume was 14.80 mL (0.01480 L). %PDF-1.5 %���� which is the end point. Eriochrome Black-T(EBT) is the metal ion indicator used in the determination of hardness by complexometric titration with EDTA. Therefore the total hardness of water can be determination by edta titration method. xڴVi��H�+�1ъ��vw[����C�� ���+���h��Շ8�졖q���~�u� 56 15. This method is based on Method 2340 C of Standard Methods for the Examination of Water and Wastewater , 22 nd Edition. EDTA Titration Calculations The hardness of water is due in part to the presence of Ca2+ ions in water. Discussion The preferred method for determining hardness is to compute it from the results of separate determinations of calcium and magnesium. Determination of Total hardness Repeat the above titration method for sample hard water instead of standard hard water. Chelometric Titration : The Determination of Water Hardness and Water Filtration Things for the lab notebook and to be included in the lab report: 1. EDTA is standardized with primary standard CaCO 3 To simplify calculations with hardness we use CaCO 3 titer = mg CaCO 3 mL EDTA After EDTA is standardized, we can use the ratio to determine the hardness of a water sample by titrating with EDTA and using the CaCO 3 titer. which is the end point. Determination of Permanent hardness Take 100 ml of sample hard water in 250 ml beaker. Complexometric Titration with EDTA Determination of Zinc Unknown 1. Reporting Results When reporting hardness, state the method used, for example, “hardness (calc. These hard water cations include calcium, magnesium, iron, zinc and the other polyvalent metal ions. Course. Share. Use the volume and molarity of EDTA to calculate the water hardness … When the total hardness is less than the sum of carbonate and bicarbonate alkalinity, the hardness is due to carbonate hardness only. Titrate the solutions with 0.01 M EDTA until the color changes from wine red to blue. Comments. Complexometric Determination of Water Hardness. CHM 101/102Water Hardness: Determination with EDTA• Procedure (Titration of Sample) Use a volumetric pipet to dispense 50.00 mL of your hard water sample into a 250 mL flask. Which one is the best for RCC concrete, M-sand or river sand? M105 Determination of the Total Hardness of Water by EDTA Titration and Flame Photometry Object To determine calcium and magnesium in a sample of tap water by titration with EDTA and then to … These hard water cations include calcium, magnesium, iron, zinc and the other polyvalent metal ions. Types of hardness is discussed. "~��� � �8"�A��� � d�\ �R����a� Q��� 0 �:c endstream endobj 73 0 obj<>stream Experiment 8 Determination of Total Hardness of Water by Complexometric Titration Lab instructor-Andrew Cho William Parnell 4/11/ Abstract: The hypothesis for this experiment was to determine if complexometric titration technique can identify the total “hardness” of water … EDTA – ethylenediaminetetraacetic acid (1:1 mol ratio between divalent metal … When the hardness is numerically greater than the sum of carbonate and bicarbonate alkalinity the amount of hardness that is equivalent to total alkalinity is called the carbonate hardness and the balance as noncarbonated hardness. 2. (5 Pts.) Because EDTA has four acidic protons, the formation of metal-ion/EDTA complexes is dependent upon the pH. Determination of Water Hardness by EDTA Titration James Harvey*, Sara Abuhad, Emmanuel ml Total hardness = Volume of EDTA solution consumed X1000 Volume of the hard water taken … Transfer 50 mL of tap water to four different Erlenmeyer flasks. ENVIRONMENTAL HEALTH AND SAFETY Hazards Assessment: This method involves the use … Adjust the pH of 100 mL (4 deliveries … Complexometric Titration with EDTA Chemistry 3200 Complexometric Titration with EDTA In this experiment you will use ethylenediaminetetraaectic acid (EDTA) to determine metals in aqueous solution by complexation titration. Report by Austin Jones February 5th, 2020 Professor Paul Gilletti. Water Hardness Analysis Example 3 A 100 mL (0.100 L) sample of tap water was titrated with 0.0100 M EDTA solution. Calculations: • ppm (Substance) = mL of EDTA used in titration/ mL of water sample x 1000 ppm . EDTA DETERMINATION OF TOTAL WATER HARDNESS AND CALCIUM 3 lab periods Reading: Chapter 11, Quantitative Chemical Analysis, 8th Edition, Daniel C. Harris (7th Edition: Chapter 12). CHEM 217 Lab #4 Determination of Water Hardness with EDTA using an ion-selective electrode Name: Simran Kaur ID: EDTA reacts quantitatively with both calcium and magnesium ions in a 1:1 stoichiometric ratio. Neither titration includes an auxiliary complexing agent. Determination of Hardness of Water Sample . reported. Choose the indicator & start the titration. Hardness EDTA as mg/L CaCO3 = (A*B*1000)/(ml of Sample) Where: A = ml EDTA Solution Used. The higher the pH, the sharper the endpoint. x�bf THANKS. This is equivalent to 1 gram of CaCO 3 in 10 6 grams of sample. Adjust the speed of the drops from the burette. It may be used to determination of water hardness. Hence the pH is fixed to 10 ± 0.1. … Report the water hardness as ppm CaCO 3 of a 50 ml water sample that required 32. Note the volume of titrant added (V1 ml). Dilute 20ml of the sample in Erlenmeyer flask to 40ml by adding 20ml of distilled water. Required fields are marked *, In this article, we are going to talk about the determination of hardness of water by EDTA titration method.The causes of hardness of water is by, When the hardness is numerically greater than the sum of carbonate and bicarbonate alkalinity the amount of hardness that is equivalent to total alkalinity is called the, The calculation of hardness in water by EDTA titration can be found by adding a small amount of a dye such as, Add EDTA titrant to the sample with vigorous shaking till the wine red colour just turns. hardness are principally bicarbonates Ca(HCO3)2 and Mg(HCO3)2 and sulfates (CaSO4 and MgSO4). Hardness due to such causes is called pseudo hardness. Guarantee Your Academic Success! The salts causing. Procedure for calculation of hardness of water by EDTA titration. This dye-stuff tends to polymerize in strongly acidic solutions to a red brown product, and hence the indicator is generally used in EDTA titration … A total of 3 titration trials were completed to find the average molarity of the EDTA, and the average water hardness of unknown water sample #40. When all the ions are complexed the solution will turn blue. Hardness that is removed by this process is referred to as temporary hardness while that which remains after boiling is called permanent hardness. What is the biggest cost in the construction industry today? Write the equations for the endpoint color change of Eriochrome Black T (EBT) with Mg+2 3. Calculation Hardness… When boiling water … It may be used to determination of water hardness. While … View lab report (titration).docx from CHEM 217 at Concordia University. Calculation of EDTA titration results is always easy, as EDTA reacts with all metal ions in 1:1 ratio: Mg 2+ + EDTA 4-→ MgEDTA 2-That means number of moles of magnesium is exactly that of number of moles of EDTA used. Water Hardness is typically determined by an EDTA titration buffered at a pH of 10 (condition for maximum complexing). Your email address will not be published. Select a definite volume of water sample. Your email address will not be published. EDTA and the metallochromic indicators used are involved in complexation reactions with the magnesium and … A] DETERMINATION OF HARDNESS OF WATER BY EDTA METHODPart I: Standardization of EDTA solutionPart II: Hardness of water sample:B] REACTIONSC] CALCULATIONS Transfer 25.00 mL of the diluted unknown solution to four different Erlenmeyer flasks. Add 5 mL of ammonia-ammonium buffer and Erichrome Black T indicator. Calculations: • ppm ( Substance ) = mL of the indicator 3... 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Disodium salt of EDTA used in titration/ mL of EDTA is shown in 22-1!, and 15 drops of the indicator and 3 mL standard solutionof EDTA like hardness! To several hundred mg/L as CaCO3 the above titration method for determining hardness is less than the conventional gravimetric (! Ppm CaCO 3 in the construction industry today attain suitable condition i.e pH level above 9 the. �I�X��J �za�z�I7��|��P! �I$ 1 '? L'���W���P1 % ߂SJ��ָE�U�mʊL�l�/�jm���6�O��V? ̙V��߳� g0��c�l��w�. Four acidic protons, the sharper the endpoint write the equations for the titration of Ca+2 EDTA! Usually expressed as ppm CaCO3 2 mL b = Mg CaCO3 equivalent 1... Mg++ ions, zinc and the other polyvalent metal ions the various tests done in environmental engineering lab of and! Mol.Calculate the molarity of the sample is diluted with distilled water to reduce concentration. From water Chapter of Applied Chemistry I Subject for all engineering students are principally bicarbonates (., iron, zinc and the other polyvalent metal ions the higher the pH is fixed to 10 ±.... Be used to determine the unknown calcium concentration in a 1:1 stoichiometric ratio precipitation of CaCO3 and (... Quantitative determination of water sample 7Yq? �I�x��j �za�z�I7��|��P! �I \$ 1 ' L'���W���P1! X 1000 ppm determining the Moles of Ca 2+ and Mg ( HCO3 2! It is assumed that the total hardness in determination of water hardness by edta titration calculations" water by EDTA video... Complex ions more rapid than the sum of carbonate and bicarbonate alkalinity, the sharper the color! In Erlenmeyer flask to 40ml by adding 20ml of distilled water to reduce concentration... These procedures were more rapid than the sum of carbonate and bicarbonate alkalinity the... Hardness that is removed by this process is referred to as temporary hardness while that remains.
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2021-07-23 23:08:04
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https://briankoopman.com/vagrant-pihole/
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# Testing out Pi-hole, Hold the Pi
I had come across Pi-hole a while ago and was recently inspired by someone on Twitter to test it out. Unfortunately I didn’t have a Raspberry Pi on hand, having just used my Pi in a Christmas present. My solution was to spin up a virtual machine (VM) on my desktop and test it out. Since VirtualBox can’t emulate ARM processors we can’t actually use Raspbian, so I used Ubuntu. The test went well and I soon had a virtualized Pi-hole blocking ads on my network (including on my phone)!
When I was done for the night I shutdown the virtual machine and was sad to see ads again, particularly on my phone. I came close to ordering another Raspberry Pi, however decided to go ahead with a more permanent solution involving some sort of containerization or virtualization on my home server. The server isn’t much, just an Intel Pentium G3220 Haswell with 4 GB of RAM. The limited resources made me initially think docker would be ideal, rather than leaving a VM running on the dual-core machine all the time.
I don’t know much about docker, but since it was still holiday break I thought it would be good to finally learn something about it. I ran through the get started tutorial in the docker documentation, which was actually really neat, I recommend you check it out if you’re at all interested. However, I ended up realizing that having a web server already running on this machine, and Pi-hole requiring use of port 80, complicates things beyond what I wanted to deal with. I had attended a talk about Vagrant last year, and thought I might make use of that experience. For those who aren’t familiar with Vagrant, it is a program which allows you to build and manage VMs, with the ability to interface with many different services, though for this we’ll be using VirtualBox.
So we’ll be walking through steps to setup vagrant on your computer, provision a VM for use with Pi-hole, and the initial Pi-hole setup. You can run this on any computer, though for any sort of long term use, you’ll likely want to set this up on something stationary and always on (which I suppose is why a Raspberry Pi makes such a great target device.)
# Vagrant
We’ll need two things, vagrant, and virtualbox, which acts as a provider for vagrant. My server runs Arch Linux, to install these we’ll just run:
If you’re on a different system I’ll leave the installation to you.
## Quick Intro
Vagrant has a very fast and easy to follow Getting Started Guide. The pages are short and they go by quick. If you want to get familiar with vagrant quickly, I’d recommend going through that. We’ll do enough to get the VM up and running, but won’t cover everything in their guide.
Vagrant uses what they call a VagrantFile to configure a VM (usually referred to as a box.) Perhaps the simplest VagrantFile defines only the VM box. For example,
This tells vagrant that we want to use the “ubuntu/xenial64” box from their publicly hosted catalog of boxes. Anyone can upload these boxes, so the usual caveats about being careful with what you trust come along with it. That said, it appears the ubuntu account looks to be official.
If you’d like to try this out, create a new directory and put the short configuration above into a file called VagrantFile. Once you’ve made your VagrantFile all that’s needed is to run:
This will pull the xenial64 box and start it up. You can open VirtualBox and watch this happen. You can then connect to the new machine with:
You should be at a prompt within the VM now. Neat, right?
## Provisioning the Pi-hole VM
We’ll make just a few changes to that basic VagrantFile.
Let’s walk through this and see what’s going on, starting with lines 1 and 2:
These are modelines, telling emacs and vi that we’re looking at ruby, which is what the VagrantFiles are in. These aren’t required, but they’re common to see.
Line 4, the Vagrant.configure("2") line, tells Vagrant which configuration version we’re using. Don’t change this. We already know config.vm.box specifies the box we want to pull. config.vm.hostname sets the hostname we’ll use on the VM to “pihole”. config.vm.provider sets the provider to be “virtualbox”, which is is by default, but this allows us to specify some more options (which we’ll run through in a minute. Finally, config.vm.network specifies the network to be a “public_network”, which for VirtualBox makes it a “Bridged Adapter”, this allows us to assign the VM an IP as if it is directly connected to our local network. We then set this IP on the rest of the line to be 192.168.1.100. Set this to whatever you want, ideally outside of your router’s DHCP address range.
Let’s look now at the options set in config.vm.provider, lines 7-13.
This does the resource limiting for the VM, limiting the box to use of 1 CPU, and 1024 MB of RAM. (Note with this few resources, it could take a little while to boot, be patient. Vagrant defaults to a 5 minute timeout, if it doesn’t boot by then it’ll throw a warning. If you can, you can try increasing the resources available, or increase the default timeout with config.vm.boot_timeout provided in seconds.) The usb options explicitly disable USB passthrough. I do this simply to ensure any USB device I plug into the server doesn’t show up on the VM too.
Then to provision the box we just need to run vagrant up.
A successful vagrant up will produce output similar to this:
If this is your first time running vagrant up it’ll also spend time downloading the box image. Note the Connection reset and Remote connection disconnect warnings are just us trying to ssh before the ssh service has come online. You can now connect to the VM with vagrant ssh.
# Installing Pi-hole
Now we just need to install Pi-hole. For this I refer to their github page. They provide a simple one-liner which pipes to bash, not ideal. During my first installation I followed “Alternative Method 2” and checked out the script I was running. If you’re trusting enough, use the one-liner. We have to check one thing before moving forward though, our static IP interface, to do so run ifconfig, and note which interface is associated with your assigned static IP (in this example 192.168.1.100), for instance enp0s8. Once you have noted that, run installer.
I won’t cover most of the dialogues, they’re pretty straight forward. You’ll want to select the interface we noted above at the “Chose An Interface” option. (If you forgot to note which interface, I can almost guarantee it’ll be the second option, since vagrant sets up two network interfaces, the first for its own use, the other for the public network.
Pi-hole needs to know where to point its upstream DNS queries, since it acts as a middle man. Use whatever you feel like here, Google is a safe bet. I decided to try out Quad9. This is also configurable from the Pihole interface so don’t spend too much time thinking here.
The potentially tricky part is the network configuration, you’ll reach a screen that looks like this:
We don’t want to use this, as it is for the first network interface, not our public network bridged adapter, so select “No”. Then we’ll enter our assigned IP from the VagrantFile like so:
This is followed by specifying our gateway, which is likely your router, commonly (and in my case) 192.168.1.1, so enter that here:
You’ll then be asked to verify the settings, it should look something like this:
The last two prompts are about the admin interface, which is neat, you should install it.
If everything goes smoothly you’ll land on an “Installation Complete!” page like this:
You should note down the Admin login info, as it can’t be retrieved after this. (Note if you need to redo this for whatever reason, just run the installer again and select reconfigure. In more dire circumstances we can remove the VM and reprovision with vagrant destroy and another vagrant up.)
Now we can point our browser to 192.168.1.100/admin, you should see the pi-hole dashboard:
You have several options for configuring your devices to use your new VM as a DNS provider. They are well enumerated on the Pi-hole discourse.
I would prefer to go with option 1, configuring the Pi-hole as my router’s only DNS provider, however I don’t want this experiment to negatively affect my housemates, so I went with option 3, configuring each device individually. This allows me to use the Pi-hole and doesn’t force it upon my housemates. I have several devices with different configurations, so I’ll go over configuring each of them.
## Android
To start, my phone, perhaps the primary motivation for setting this up, since Google has been forcing links to open in Chrome, which lacks ad block on mobile. I use an Android phone, which at the time of this write up is running version 8.0.0.
To setup the pi-hole as your Android phone’s DNS provider navigate to the Wi-Fi settings and click and hold on your home network, this should pop up a menu as shown here:
Click on “Modify network”. Scroll down to “IP settings”, where we want to select “Static”. Unless you’ve configured this previously it is likely on “DHCP”.
This will allow for input of a static IP address for your phone, along with all the other necessary details, including of course the DNS provider. Here we’ll enter the IP of our Pi-hole, 192.168.1.100 as shown here:
I find I then have to toggle Wi-Fi off and on again in order to fully reconnect, else it might look like you’re connected, but you won’t actually have Internet access.
## Linux
I am running Arch Linux on my desktop and laptop. On the desktop I am using dhcpcd and on the laptop NetworkManager (with nm-applet). Their configuration differs slightly.
### dhcpcd
I should have setup a static IP long ago for the desktop, to do so, add these details to your /etc/dhcpcd.conf file:
Be sure to use an available IP address, and again one outside of your router’s DHCP range.
### nm-applet
nm-applet is similarly easy to configure, just open up the the connection editor, navigate over the IPv4 Settings and enter the following, substituting in a suitable IP address:
# Wrapping Up
That’s it! We’ve created a Pi-hole instance on a virtualized Ubuntu box using vagrant and configured our devices to use it as a DNS provider. You can use the Pi-hole dashboard to view how many blocked DNS requests you make on which devices.
If you ever want to undo all this though, perhaps so you can move to a Raspberry Pi, you will have to revert the individual devices’ network configurations. You can then bring down the VM by navigating to the same directory where your VagrantFile lives and run vagrant destroy. It’ll prompt you to make sure you want to actually do it, but then the VM will be gone.
Tags:
Updated:
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2020-04-08 09:07:51
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http://uncyclopedia.wikia.com/wiki/Uncyclopedia:Village_Dump/archive17?oldid=5079900
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# Uncyclopedia:Village Dump/archive17
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
## Rating System Design
The time has come. The rating system must be designed and implemented. If you want to participate in this, now is the time to get involved. See Uncyclopedia:Rating System--Chronarion 02:11, 25 February 2006 (UTC)
Wow, that was so impersonal. So rough, I feel... hurt. 02:25, 25 February 2006 (UTC)
I've felt your concerns and revised my statement in the New-Dump. It now carries middle english flair. Imagine I had an eyepatch on as I cried out my statement. --Chronarion 01:14, 26 February 2006 (UTC)
## The Robots are coming
Someone fill up Howto:Survive a Robot Uprising, thanks --Nytrospawn 20:51, 24 February 2006 (UTC)
Done and Done. I don't know whether to feel smugly superior or like your personal bitch. I'll just go nominate you for something while I think about it. Ok? Gosh, I hope so. 00:08, 25 February 2006 (UTC)
You should feel both, and indignation --Nytrospawn 01:41, 26 February 2006 (UTC)
A graced the page with a beautiful illustration. --Spin 04:28, 26 February 2006 (UTC)
## New box meta-template
First of all, Template:Box is meant to standardize template boxes, which are implemented using a whole lot of methods (usually copy-pasting code from other templates). It's fixed at 70% width to keep templates uniform, but customizable enough in everything else.
Simple usage:
{{box|
bg=#color|Image.ext|SIZEpx|
Title|
Text}}
It supports default values for optional parameters, in a sense that you don't need to specify these parameters. They are:
id=STRING
bg=#color (default #eee)
fg=#color (default #000)
align=ALIGN (default center)
title-align=ALIGN (default center)
border=WIDTHpx STYLE #color (default 1px solid #aaa)
For examples, see {{protected}}, {{minitrue}}, {{crimethink}} (converted), {{a splode}}. - User:Guest/sig 19:05, 24 February 2006 (UTC)
## "Recent Pages"
request that this hence forth be deemed "Soon to be Deleted Pages" --17:44, 24 February 2006 (UTC)
It's also where I get most of my many VFH nominations! There and the IRC cabal - David Gerard 23:06, 24 February 2006 (UTC)
There is no Cabal. 23:55, 24 February 2006 (UTC)
## printing uncyclopedia articles
Um ... I decided I wanted to print out Russian Reversal and a couple other articles maybe ... and realized that there is no "Printer-friendly" option on uncyclopedia (like there is on many other wikis) What's up wid dat? -- 15:53, 24 February 2006 (UTC)
Find out how the others (mediawiki that is) did it and copy it here!--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 17:31, 24 February 2006 (UTC)
You hit 'print' and print it, and it comes out right through the magic of CSS. This actually works. Alternately, it's your own fault for using the Monobook skin instead of Classic, which is the One True Skin even if no-one's yet bothered putting the Google ads into it - David Gerard 23:36, 24 February 2006 (UTC)
## Stupid underline...
How do you get rid of the underline on a link? ---- 02:46, 24 February 2006 (UTC)
"Preferences" -> "Misc" --—rc (t) 02:54, 24 February 2006 (UTC)
I think you meant something else, so disregard. --—rc (t) 03:00, 24 February 2006 (UTC)
Do you mean in your sig? Cause i can do that for you if you want. 02:57, 24 February 2006 (UTC)
<span class="nounderlinelink">[[link]]</span> -- 02:58, 24 February 2006 (UTC)
## Templates
Is it possible to use a template from a different wiki? (What I'm going for is a Babel template from Wikipedia) ---- 02:36, 24 February 2006 (UTC)
Not directly as far as I'm aware but you could always copy the code of the template from wikipedia to here (although youmight find that bable templates work differently here, I havn't looked) --The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 14:40, 24 February 2006 (UTC)
## A Noob Apology
To anyone I offended by not offering a Thank You for their help in answering my many questions: Thanks.
I would have been more formal, but everything here at the Dump felt rather anonymous, so I didn't really think there was a point. But now that I've looked more thoughtfully at some of the posts, I realize I was acting a bit like a leech. So once again, Thanks.
--McAtee08 01:59, 24 February 2006 (UTC)
I'm confused...why are you thanking me for being offended? 02:53, 24 February 2006 (UTC)
Perhaps I should have specified by saying: "Thanks....for the help."--McAtee08 03:42, 24 February 2006 (UTC)
That's right courteous of ye. Enjoy Uncyc. --—rc (t) 04:27, 24 February 2006 (UTC)
Naw, by being specific you'd have deprived me of a smartass comment. And we wouldn't want that, would we? 15:21, 24 February 2006 (UTC)
## Remakes
The DoomPod article got deleted. So am I allowed to have a go at making a DoomPod article? Or does it have to remain dead?
You're allowed to make a new one, but you can't just repost the old one. Also, in the future, please sign your comments (use ~~~~). --Sir gwax (talk) 17:47, 23 February 2006 (UTC)
Excellent. Thank you! --00tinytim00 17:51, 23 February 2006 (UTC)
## Uncyclopedia Book of World Records
I got this idea (I wasn't drinking this time) for an Uncyclopedia book of World Records, kinda like the Guniess book of World Records, only without facts (and not for drunk people . . . . ok they can use it too). It would essentially follow a similar format to Guiness, that is, it would have some large categories, and within those we have a record and short blurbs about it. We could easily fold the Worst 100 lists into the world record book as well. I think the Guiness Book would be an excellent target for parody, I mean, just look at some of the records in there, most clothes pins fit on a person's face, like that's useful (to non drunks). Anyway, just some food for thought. --Jsonitsac 16:24, 23 February 2006 (UTC)
This sounds like a good idea. Just make sure it's like, not horrible, and doesn't degenerate. Start an article, but keep the quality high within it. If it gets good enough, we can start folding things in. --Chronarion 00:08, 24 February 2006 (UTC)
## Noob Question
How do you add links to an article so it doesn't end up as a dead end?
And: If you are trying to put a picture or graphic in an article, what format must it be in? --McAtee08 03:37, 23 February 2006 (UTC)
The instructions at Wikipedia are pretty decent these days, and things work basically the same here as they do there with the exception of some advanced things you don't need to worry about. -- 04:33, 23 February 2006 (UTC)
Plus McAtee, it'd be polite of you to thank people after they post replies to your questions. Thanks. -- Sir Codeine K·H·P·B·M·N·C·U·Bu. · (Harangue) 09:52, 23 February 2006 (UTC)
Thanks.....again.--McAtee08 01:55, 24 February 2006 (UTC)
You are welcome. -- 04:32, 24 February 2006 (UTC)
## Uncyclopedia: The Book
Would it be possible to print Uncyclopedia as a book, and donate the proceeds to charity? Or would that still break the Creative Commons license? - TankRamp
That's something that I've been wondering about recently as well. I'm not sure what the answer is but I can tell you that it is not an issue right now because there isn't enough truly good content on Uncyclopedia to make a print Best of Uncyclopedia. If we did sell it though, I would hope that the profits would go to buying Uncyclopedia more server power/donating to Wikia. It would also be kind of nice if we could get rid of those google ads in the corner. --Sir gwax (talk) 21:11, 22 February 2006 (UTC)
I've been thinking about this for a long time, since somebody (Nytrospawn?) mentioned it at the Dump months ago. Unfortunately it's my understanding that using Uncyc content, under our current license, wouldn't be allowed because even if we didn't profit from it, the printer would. But I know little to nothing about copyrights, so I could very well be wrong.
I'm not sure I agree that we don't have enough content for a book - we have over 130 featured articles at the moment, and from what I've seen non-mass-printed books aren't that cheap. I've ordered from Lulu a couple times at about $7 for a 115-page, black-and-white, no-frills book (not including shipping) - and that's with no profit margin, just manufacturing costs. I'd think we'd have to keep the length reasonable to make it attractive. (Note that I personally don't think a lot of the featured articles are funny, but the people have spoken.) Also, there is already an Uncyclopedia in print, so we'd probably have to go with another name. --—rc (t) 21:26, 22 February 2006 (UTC) Because a decent portion of our good articles are single-author, and because many of our top authors are still around, it wouldn't be impossible to re-license content specifically for a book. But in the case of images made from copyrighted sources, we would probably need to retain a lawyer to determine what we could print. -- 22:14, 22 February 2006 (UTC) Well, I don't know about copyriht, but I love the idea. Also I think that the authors of the printed articles that can be considered as such, should have right to be named in it if they want to. If you can't make money out of it, maybe the recognition can be helpful for some Curriculum Vitae. I hope ordering a copy from outside the states wont be too expensive.--Rataube 04:16, 23 February 2006 (UTC) Id buy it. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 14:14, 23 February 2006 (UTC) I'm not so sure. • First who'd buy the book when you can just go online and look at Uncyclopedia for free. • Second, how do we determine what's worthy of getting in the book or not? According to the front page we have over 16,000 articles, that means we'd have to pick and choose the articles that get in, and that would probably mean a lengthy voting process, and few of us care to vote in these type of things anyway. • Third, the publisher would probably make us submit to an editor who may not think like we do and ruin some perfectly good articles. • Fourth, we'd probably get sued by somebody. It helps that we're a relatively obscure site on the internet (better then a teenage girl's blog but still. . .) which helps us in terms of dealing with copyright issues. Also, we have some stuff on here which could easily piss people off. While clearly intended and distributed as parody, and the standard for libeling famous people is much lower then non-famous, I think we could easily be skating on thin ice.--Jsonitsac 16:14, 23 February 2006 (UTC) 1. To some extent, the same goes for Sparknotes or the Bible. (That's right, I just compared Uncyclopedia to THE BIBLE.) I don't think anyone believes the Uncyclobook will hit the New York Times' bestseller list, but to a lot of us it'd be a cool thing to have. 2. Well, there are the featured articles, which in themselves are a lot of content. But yeah, if we wanted to use other stuff it'll be a pain to decide what should go in. 3. If we used a print-on-demand service like Lulu, we could control everything that goes into it. (Formatting and things are a pain, of course, but I'm sure someone here has some experience in the area.) It costs more per unit and there are some other limitations, but we wouldn't have to worry about having other people mess with our work (unless we wanted them to), or things like production numbers, etc. 4. I don't know much about laws'n'stuff so I won't say anything here. Re: Isra, it's true that a some of our best writers are still around, so getting their permission shouldn't be hard (assuming they don't want payment...), but some of them aren't. We could of course search through histories to find original authors and try to contact them if we wanted to use older pages, but that's a pretty tall order, 'specially for IPs. And even determining which individual edits could be used might be difficult (but again, I don't know too much about that stuff.) --—rc (t) 18:43, 23 February 2006 (UTC) If there was sufficient money, and it was being donated to chairity, like being given to orphans, I could become an orphan. Just let me know the dollar (or euro) amount, ok? 19:37, 23 February 2006 (UTC) If you wanted to do a commercial version, what we can definitely do is simply ask the authors to write a final version of their pages for the book. It could be possibly to split proceeds a couple of ways in that manner, which both fulfills our license, and makes everybody happy. --Chronarion 00:10, 24 February 2006 (UTC) If you do come up with a way to publish it make sure that it comes with a pencil and some white-out tape, so that the user can make his own edits. Or at least a picture of the afformented on the inside cover... Then there could be a TV mini-series based on Uncyclopedia, then a video game, then a film by Uwe Boll...ah! Just think of the possibilities! You'd be rich and famous, except maybe for the wealth and fame...well you'd be you, anyway. Modusoperandi 05:27, 25 February 2006 (UTC) ### Our License I think the key to our license question is found here. The key clause is "You may not exercise any of the rights granted to You in Section 3 above in any manner that is primarily intended for or directed toward commercial advantage or private monetary compensation." I think, we could be in violation of the license for a totally different reason however. A CCL seems to imply that anybody can edit the work, something which is impossible if we were to put uncyclopedia in book form. Of course, I'm not a copyright lawyer, so if we do publish a book, we ought to check with them first. Jsonitsac 00:33, 24 February 2006 (UTC) Any one can still "edit" the works in the book in that they can make derivative works under the same liscense. -- 00:48, 24 February 2006 (UTC) Also, from my reading of the license, we could publish a book under the current license as long as we sold it at cost. -- 03:22, 24 February 2006 (UTC) ### Fair Use Another major concern is over fair use, e.g. photoshoped pictures, or articles about companies. This wikipedia article seems to put it in layman's terms [1]. The main issue we have to deal with is are such items parodies or satire. It may seem like a weird thing to worry about, but apparently the courts seem to differentiate the two, and give more leeway for parody then satire. As I said earlier, we may be trampling on those type of issues with some of our content, but because we are a relatively obscure website, we don't have to deal with such suits. A book and more attention that it brings with it could change that dynamic. Jsonitsac 00:33, 24 February 2006 (UTC) I think as far as text goes, we are usually pretty safe, but I would go so far as to say we would need to hire a lawyer to look at images. -- 00:50, 24 February 2006 (UTC) ===follow the money===--Chronarion 03:38, 26 February 2006 (UTC)ON! if Uncyclopedia does produce anything and the proceeds go to charity ... could we please try to pick a non-contraversial charity? like ... one we vote on maybe? -- 01:03, 24 February 2006 (UTC) I think that if the proceeds go to anything but server costs, even charity, we would need to relicense the content. If we do that, I would suggest proceeds go to UOWRPF - the uncyclopedia.wikia.com Writers' Rent Payment Fund. -- 03:26, 24 February 2006 (UTC) yeah, I think paying server costs is probably what it ought to do. -- 15:42, 24 February 2006 (UTC) Can we take off administrative fees first? (you know, for processing) --Sir gwax (talk) 18:41, 24 February 2006 (UTC) DIRECT TO THE KILL ALL BABIES FOUNDATION! --Chronarion 03:38, 26 February 2006 (UTC) ## QVFD with DynamicPageList? We could make QVFD nomination more efficient by using the dynamicpagelist exetnsion. A user could flag the article with "{{!}}", which would add it to the Huff Requests category, where admins could check much like QVFD. All deletions are archived in logs anyway so the only forseeable problem with records is having to wade through the logs to find them. - Nonymous 21:08, 21 February 2006 (UTC) A few problems with using DynamicPageList for maintenance monitoring: • Additions to the list won't show up in user watchlists • Comments cannot be added to the listing • Pages cannot be struck without removing them entirely DPL is a nice feature, but it really doesn't work in these circumstances. --Algorithm (talk) 22:12, 21 February 2006 (UTC) My problem is, again, that one must edit the page to categorize or template it. And that is just pointless for several reasons: 1. Pages often get re-created. When we still had Template:QVFD, I would often delete pages two or three times in a row because people trying to tag them would recreate them after a deletion. This is stupid. 2. If you find 5 or 10 bad ones in a row, you have to edit each one to tag it with a template or category. This is stupid when you can just add them all to the QVFD page at once or in batches. 3. The authors can *easily* remove categories and templates from their pages, with high odds of not getting caught at it. Users can not easily remove entries from the QVFD. Because of this. relying on templates/categories for QVFD is stupid. If a page is good enough to not QVFD, and worth putting a template on, use {{NRV}}. 4. The QVFD allows repeat offenders to be easily caught. If the page is re-created the red link on the QVFD turns blue. Almost all links on the QVFD should be struck-out (with reason given) or red. Easy to spot re-created or missed pages there. 5. Larger history: If a page is edited to templateify before deleting, this just increases the size of the deleted history (which are never deleted, they remain part of Uncyclopedia's deleted histories indefinitely). As is, I can see no cause to have any sort of QVFD/category/DPL template in the face of such anti-reasons. Just put the page on the QVFD. It is a one-glance patrolled status page for all QVFD entries. And as stated before, (some people say "Don't delete my page without VFD or QVFDing it!")... QVFD = Deletion. The only (mostly) reason we have it is because not everyone can delete on site. Pages on the QVFD should be insta-delete worthy. Like spam, "my friend is gay", sub-stub crap, and cut-pastes. Excessively putting pages on the QVFD that are VFD/NRV/MTU is discouraged (or should be). My 3 cents. --Splaka 03:26, 22 February 2006 (UTC) ## A Question Unanswerable The help page said to put unanswerable questions here, so here goes: The statement below is true The statement above is false Which statement is true? Well that's obvious... The third one. Since it's a question, it's correct by default. 21:22, 20 February 2006 (UTC) The third one isnt a statement, its a question. Insufficient data -- 05:19, 21 February 2006 (UTC) The question is faulty because it doesn't specify the set of statements from which to choose the true one. "Which statement of the above two is true?" would be better. --—rc (t) 05:24, 21 February 2006 (UTC) False » Brig Sir Dawg | t | v | c » 05:56, 21 February 2006 (UTC) Put simply, Tompkins wins. 21:29, 21 February 2006 (UTC) That depends. Which of the two statements can create a rock so heavy that even him can not lift?--Rataube 21:54, 21 February 2006 (UTC) Emacs can create a core dump it can't edit - David Gerard 23:11, 21 February 2006 (UTC) I agree with Tompkins. "Tompkins wins." is both a statement, and is true. -- 22:24, 21 February 2006 (UTC) fosslefy me Heh. 22:28, 21 February 2006 (UTC) Actually, there is only one sentence, broken into three lines, which together constitute a question referring to statements that do not appear to be present surrounding the question. Therefore, poop --Mindsunwound: (NS) Cream Of Meat Vacuum 22:35, 23 February 2006 (UTC) The statements are contradictory and as such, neither is true. --Sir gwax (talk) 13:09, 24 February 2006 (UTC) The statements set up a false dichotomy. There are things which are both true and false, and things which are neither true nor false. So we must assume that either statement can quantum tunnel to its opposite state. As such, we have only probabilities of truth and falsehood, not the all-or-nothing dichotomy set up by the question.</bullshit>----OEJ 13:45, 24 February 2006 (UTC) ## New Search Feature Kate (aka zwitter) has created a new search feature for Wikia. This is now live at Special:Search on Wikicities, Uncyclopedia, and Memory Alpha. As well as finding results on the current wiki, it will show you 5 results from other wikis. Using the advanced search, you can select which wikis you want it to search. For help, see Help:Searching and the full manual at Wikia Please report any problems using bugzilla at http;//bugs.wikia.com or send an email to our new help email address: technical@wikicities.com. --Angela 19 February 2006 09:16 (UTC) I hate this crap! When you search for seomthing it wont take you directly to the article, first you have to go through the little Google-esque crap. Give me back the old search! 19:54, 19 February 2006 (UTC) Agreed, it's terrible. And believe it or not, I don't care if the Muppets wiki has a page with the same name as my search. --—rc (t) 20:25, 19 February 2006 (UTC) Yeah, given that we're not on wikicities, I don't want to see stuff there. I know, I know, technically we are hosted by wikia and all, but we're not a wikicity. Also, those other wikis contain factual information, and it's really pointless for Uncyc. --[[User:Nintendorulez|Nintendorulez | talk]] 17:01, 23 February 2006 (UTC) Bring back the old search. Without being rude, it's the lamest excuse for a feature ever. --Boy Toy bitch at me 20:38, 19 February 2006 (UTC) I think this can stay, could actually be useful, BUT, the GO BUTTON HAS TO BE THE DEFAULT option, not the search!.--Rataube 21:13, 19 February 2006 (UTC) The go button has now been fixed. Also, you can now disable the "other wikis" search by writing 1 in MediaWiki:Wikiasearchdefaultlocal. Angela 22:22, 19 February 2006 (UTC) "Fixed"? No likey... I miss having the "Go" button taking you to either the article or the creation-page for an article... :( --⇔ 22:27, 19 February 2006 (UTC) THIS IS AN OUTRAGE!! I DEMAND ANGELA'S BLOOD! 23:10, 19 February 2006 (UTC) I dont see the benefits of this... It adds some features that noone will use and just makes it take longer to get the results we are used to and expect to get. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 03:38, 20 February 2006 (UTC) I hate it. While I appreciate the effort in trying to give us new features, I think the old system was more useful. ~ T. (talk) 03:56, 20 February 2006 (UTC) THE GO BUTTON NEEDS TO BE THE DEFAULT...not the Search It's useful in certain circumstances but it's annoying to have to be forced learn to click go instead of just hitting the enter key. -- – Mahroww a.k.a. 07:18, 20 February 2006 (UTC) Currently if you put in an actual article title and hit go, it takes you to the article. Also, I put in MediaWiki:Wikiasearchdefaultlocal as 1, lets observe the results.... --Splaka 07:32, 20 February 2006 (UTC) • But if you type in the actual article title and press enter (all from the keyboard without having to click the mouse) the default is Search which is needless processing time for the most part. If the default were the Go button it wouldn't be different from what people have grown used to. That seems like it'd be an easy fix. -- – Mahroww a.k.a. 08:35, 22 February 2006 (UTC) The default is go, at least in Mozilla. If you get the title right of course. --Splaka 08:43, 22 February 2006 (UTC) Well, not everyone uses Mozilla. --[[User:Nintendorulez|Nintendorulez | talk]] 17:01, 23 February 2006 (UTC) I found two errors in it. 1) The shortcuts (such as UN:DUMP) don't work. 2) It does not recognise namespaces (typing User:Acid Ammo won't take me to the page). --Boy Toy bitch at me 16:07, 20 February 2006 (UTC) I've noticed that too, and there's no way in hell I'm going to continue to type out Uncyclopedia:Village Dump. 21:25, 20 February 2006 (UTC) *Against NOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOO -- 22:30, 21 February 2006 (UTC) <small/>Yes that means I don't like it COMMA you fool PERIOD</small> You saw nothing...I never wrote that...blame...ummm...Tompkins...he said that...it acctually seems to be fixed...-- 22:35, 21 February 2006 (UTC) I also must go on record and say that I absolutely HATE this new search. It's made navigation via shortcuts all but impossible, and creating new pages has become a much more abstruse process thanks to the Google-ific way the "results" are displayed. Also, as Acid has pointed out, it will not easily recognize User spaces unless they are typed verbatim (case sensitive!) This is, in no way I can see, a useful addition, and it actually ranks as a hinderance and a useless complication in my book. Please Revert. --The King In Yellow (Talk to the Dalek.) 16:10, 22 February 2006 (UTC) Revert. Our content is largely not compatable with that of Wikicites. Also, it's not recognizing shortcuts correctly. --Chronarion 00:13, 24 February 2006 (UTC) I actually think this is a fine feature for most situations, because it allows the user to search for information across multiple Wikicities. It just sucks to have it here. Uncyclopedians want an ocean of funny, not facts. Revert this well-made but badly-placed piece of shite!--Jordanus 04:23, 25 February 2006 (UTC) ## Im still alive Just letting you guys know --Nytrospawn 19:06, 19 February 2006 (UTC) Want us to do something about it? 03:44, 20 February 2006 (UTC) Yes--Nytrospawn 22:44, 20 February 2006 (UTC) 22:51, 20 February 2006 (UTC) - Nytrospawn taken care of. --Boy Toy bitch at me ## A Noob Question Someone put a lot of effort into writing a large, mostly unfunny article about the Amish. I want to give it a total facelift, but I know I need to place a tag first. How do you place a tag, such as NRV? Also: How do you make the little colored "fact panels" that appear on the right hand side of a page about a country or a famous person? I'm talking about the ones that might list important dates, locations, or facts. --McAtee08 16:31, 19 February 2006 (UTC) Hi McAtee08. Firstly, Templates are placed by enclosing the appropriate name in curly brackets. For example: {{rewrite}} would place this tag: --tag removed from archive for maintenance reasons-- or, {{stub}} will place the stub template like so: This article needs to be expanded. This article is a stub. The article submitter is a hack. You can help Uncyclopedia by expanding it. Some templates can be timestamped - {{wip}}, {{MTUsign}} and {{NRV}} for example. What this means is that when placing the template, you should use the following format: {{Templatename|~~~~~}}. The five tildes (~) will place a timestamp ("This template placed on...") on the template when you click "Save page", like so: --tag removed from archive for maintenance reasons-- Much, much more info about templates and their usage can be found here, and a full list of Uncyclopedia templates can be found here. As for the infoboxes, there's a blank template for creating them at Template:Infobox. For an example of how this works, have a look at Template:Infobox_France. What you need to do is create a page for the infobox template you wish to create, copy the base template there and then expand the information. Once you've saved the template (as Template:Infobox_Yourpagename), you can then place it on the page as I explained above, using the curly brackets: {{Infobox_Yourpagename}}. If you want to get into heavy template editing and creation, there is a host of information available at Meta-Wiki. Hope this helps. -- Sir Codeine K·H·P·B·M·N·C·U·Bu. · (Harangue) 17:20, 19 February 2006 (UTC) Alternatively, an appropriate infobox might already exist. Incidentally, you don't need to place a tag before rewriting an article; just do it. Tagging is more useful for marking a page as needing to be rewritten by someone else (or such). --Sir gwax (talk) 18:15, 22 February 2006 (UTC) ## The Great Main Page Vote of '06 That's right, votes for the main page are here. The voting will run up to whenever the admins decide, and the winner will recieve their Main Page featured. Votes go under the appropriate headers, discussion goes under this line, blah blah blah. Any new entries are welcome. --officer designate Lugiatm 11:38, 19 February 2006 (UTC) Note the position of the featured article, image, news and Wikipedia:Template:MainPageIntro on Wikipedia:Main Page. I want to fool people. -- 05:31, 21 February 2006 (UTC) Rangley's edit is the most current version of the straight wikipedia rippoff. If you want to be able to fool peolpe, vote for his, since that is what the draft that is likely to be adopted looks like. -- 00:57, 22 February 2006 (UTC) Also, if they make minor variations to theirs, my edit would include them. Its just intended to be a straight copy (with uncyclopedia things like word of the day, WOTM, etc), and not have any extra frills. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 06:12, 22 February 2006 (UTC) One thing I would note is that both my versions and yours lack some of the details we currently have, like edit buttons and links to UnNews and such. I don't know if you altered my rip directly or just made the same decisions, but I was going to stick those in eventually. -- 06:33, 22 February 2006 (UTC) Yea, it was just laziness on my part. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 18:25, 22 February 2006 (UTC) I think we should nuke the word of the day and have the quote of the day instead. -- 01:13, 24 February 2006 (UTC) Looking at Rangeley's Edit, it does not match Wikipedia:Main Page closely enough to get my vote because of the difference between it and Wikipedia:Template:MainPageIntro, which is the most distinctive feature of the Wikipedia Main Page. Rangley's version, alas, has a much bigger headline. -- 01:27, 24 February 2006 (UTC) Maybe you missed this, but we are not trying to copy their current main page. We are trying to copy their beta page that they will soon go to, found here: [2]. I see now that the search has been removed, I will make a quick fix to mine. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 15:17, 24 February 2006 (UTC) Oh ... I didn't know that WP was changing. I don't think they should. I like(d) the entry paragraph the way it was. But if they change, we should too, in which case yours would definately be the best. :) -- 15:47, 24 February 2006 (UTC) ### Votes for Lugiatm's Rip • Votes go here. --officer designate Lugiatm 11:38, 19 February 2006 (UTC) • For, although maybe the featured image box in the example is tad large. -- 15:10, 19 February 2006 (UTC) • Against, the featured image needs to be up the top. --OsirisX 00:30, 21 February 2006 (UTC) ### Votes for Isra's Hybrid • Votes go here. --officer designate Lugiatm 11:38, 19 February 2006 (UTC) • Weak for. This is the one I like the most so far, couse of the location and size of the featured image. But I think it needs to resemble the wikipedia search-box at the top somehow.--Rataube 14:30, 19 February 2006 (UTC) • For Also because of the featured image format. It would indeed be nice if the header could be redone in a more Wikipedish style, but I don't know if that could be done well with only half the page to work with. --—rc (t) 17:13, 19 February 2006 (UTC) • For. The featured article column should have a little more minimum space and a shorter blurb though. As it is, it's going to show about 4 words per line and shoot down about three feet for anybody who doesn't have a large resolution/moniter. --Spin 17:29, 19 February 2006 (UTC) • Against. Looks horrible at 1024x768. --Algorithm (talk) 22:49, 19 February 2006 (UTC) • Comment If the format needs it, I can always shorten the featured article length. --—rc (t) 22:52, 19 February 2006 (UTC) • For: but someone should figure out how to make the size of the image be relative to the size of the browser window. -- 22:59, 19 February 2006 (UTC) • For. — 00:28, 20 February 2006 (UTC) ### Votes for Isra's Other Hybrid • Votes go here. --officer designate Lugiatm 11:38, 19 February 2006 (UTC) • For, best one there. --OsirisX 00:30, 21 February 2006 (UTC) • 4.0 --Carlb 00:52, 22 February 2006 (UTC) ### Votes for Tompkins' Hybrid • Votes go here. --officer designate Lugiatm 11:38, 19 February 2006 (UTC) • Comment I went to it...yes...and the image was that crazy Pac-Man thing...IT WAS FUCKING HUGE...scary...you might wanna fix that...-- 13:55, 19 February 2006 (UTC) • For. ya.. I've been meaning to do that, it's the only broken one. 17:04, 19 February 2006 (UTC) ### Votes for Rangeley's Edit • Votes go here. -- ~Sir Rangeley GUN WotM UotM EGA +S (talk) 15:49, 19 February 2006 (UTC) • For. I know there are a ton out there already, but me and Tompkins somewhat agreed to use this one, which looks a bit more wikipedia like. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 15:49, 19 February 2006 (UTC) • For Although none are really bad. Nice mockups, all. 16:53, 19 February 2006 (UTC) • For. Haha I only voted for mine because... well I made it. 19:13, 19 February 2006 (UTC) • For. Although I like Lugiatm's featured image format slightly more than this one, this is the best format overall. --Algorithm (talk) 23:00, 19 February 2006 (UTC) • For. Though all are quite good, this one has an edge, I think. Nicely done. ~ T. (talk) 04:02, 20 February 2006 (UTC) • For Although I'd add a few little tounches like From Uncyclopedia's crapiest articles: or some such to Did you know... and maybe the Other areas of Uncyclopedia, if we are going for a straight spoof. --The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 12:31, 20 February 2006 (UTC) • $\sqrt{(3^2-1)\ln{e^2}}$ - User:Guest/sig 16:40, 20 February 2006 (UTC) • For: Ignoring that it'll take me a while to get used to the featured image near the bottom, this is the cleanest looking (and best ripoff) of the bunch. --Sir gwax (talk) 18:27, 22 February 2006 (UTC) • For best incorperation of featured picture while staying WP like. Paulgb 22:41, 22 February 2006 (UTC) • For Best combined layout. --Chronarion 00:15, 24 February 2006 (UTC) ## Frankenstein Syndrome I have experienced a certain common, recurring theme here. Popular topics or articles often gradually fall into a decadence that makes one wonder if anyone actually thought before adding to them, or if they just gathered random parts of humor (indeed, even parts marked 'abby-normal') and assembled them together into a monster. A prime example is George W. Bush. This is a featured article, though an older one. Looking at it today, I know it would not get featured (or shouldnt). It is a messy, messy article, has some bright spots, but it lacks any remnants of organization, flow, sanity, or anything like that. But even worse, I must say, is the United States of America article. I cant look at it any longer then a few seconds before I am forced to avert my eyes in shear terror. I have read a bit of it, but frankly the article is just so retarded looking its a battle just to follow it. Add in that it is poorly written and somewhat off the topic of the USA. Just as attempts at creating life through decaying body parts can create monsters, such as the recent face transplant in France, so too can having hundreds of people try and take an article in millions of directions, which tends to happen with hot topics. I know that we are going for collaboration here, but I think the sort of collaboration in some of these popular articles is pretty harmful. It seems that many edits are not necessarilly done to make the article better, or improve it, but instead to just throw in a random joke that may or may not fit. When you let this run rampant, you get a bad article. What do I propose? There should be some serious rewrites of the popular articles, and in them we decide a direction to take them. After this direction is figured out, (eg. The USA article is written from an egocentric American view, the USA article is written from a terrorists view) and it is written in that fashion, you can have a good basis to figure out what is vandalism, and what is an addition. If it adds to the articles direction, keep it. If it detracts, remove it. I know this is a judgement call, but atleast it isnt shooting in the dark, or letting everyone and their great uncle add whatever they want to bigger articles to the point that they become Frankensteins. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 04:44, 19 February 2006 (UTC) I'm very dissapointed to see this comment has nothing to do with Isaac Asimov.--Rataube 05:05, 19 February 2006 (UTC) I support this proposal for decolonization of articles as it were. -- 05:45, 19 February 2006 (UTC) The thing is that articles tend to do this uncontrollably. This means that people sorta have to adopt articles. I've adopted god to some extent. One idea I've had is to allow multiple versions of highly popular or controversial subjects. There are some topics that can be effectively mocked in a variety of ways; for instance, the USA article can be in a serious tone, an absurdist tone, a "USA rocks!" tone, or a foreign "Americans are dumb" tone. Or a crazy "WTF" tone. But when there's only one possible article for it, everyone who wants to put in their comedic$0.02 has to jam it all in there. The result: sheer, neverending chaos. So why not create standard templates for popular articles pointing to several distinct viewpoints or comedic slants? That way, the humor in each version will be more focused and coherent, and there can be a greater range of humor overall, not just a chaotic "one-size-fits-all".--Jordanus 08:20, 19 February 2006 (UTC)
All those tones can be just different chapters inside the same aticle. It's still cohrent if, besides the whole article, you add a chapter about how foreigners see it or whatever. I prefer the adoption idea. Some user deciding which edits stay and which ones go away, as we usually do with our own articles (I do it at least). We could make a section articles for adoption or something (different from orphaned pages). I'm still desappointed this is not about Asimov.--Rataube 14:17, 19 February 2006 (UTC)
OK, I'll tell you the real reason I posted this: awhile back I rewrote the Allah article, which some had called a "cesspool of crap", into a more coherent version. I wrote the whole article from a Fundy Christian viewpoint which mocked Islam throughout the whole article, but did it in a way that made the Fundy argument look ridiculous. Since "Allah" is such a high-profile and controversial article, it garnered a lot of vandalism, crap additions, etc. Now someone has come in and completely rewritten it from a different point of view. The article is decent and funny, but then again so was mine. I don't want to monopolize the article and say that my version is the only one allowed, but I don't see how to accomadate both versions. Putting them all in one page wouldn't work, because they're so long, and combining them would just break the distinct tones of both articles. Which is why I support separating them into separate articles. You know, make "Allah" a disambig page which points to the different versions available: Fundy satire, the more general Uncyclopedia version, and any more that are appropriate. That way the different comedic slants can be kept coherent and there can be a greater range of comedy; readers can choose to read whatever version of Allah they feel like. Anyway, I'm not sure what to do because I don't know what the edit policy would be in a case like this. What do you guys think? --Jordanus 03:05, 20 February 2006 (UTC)
No joke: I was just looking at that article's history and thinking "didn't this used to be totally different, and also hillarious." I think you are totally justified in moving the new stuff to another page and restoring your version. Yours was great and it was the first one to be great. -- 03:32, 20 February 2006 (UTC)
I prefer monopolies. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 03:23, 20 February 2006 (UTC)
I ran into something similar with Babel fish. My text was about the aquatic creature (and claimed that the newfies were the original discoverers); in the next edit, someone else had overwritten it with an article about translation software. They were valid articles but were too different to combine (one's about computers, the other about fisheries) so the original had to be reposted under a one-bit-different name. --Carlb 05:01, 20 February 2006 (UTC)
This Lords and Ladies is what {{disambig}} is for!--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 12:43, 20 February 2006 (UTC)
Well, I noticed that Famine has RV'd the article in question, so as far as I'm concerned the issue's moot. I'll post a message in the Talk page to the anonymous user who rewrote the article letting them know what's been decided, and if they want to create a new article for their rewrite, that's up to them. That's what Isaac Asimov would've done. And thanks for the compliments, Isra!--Jordanus 02:04, 22 February 2006 (UTC)
Adopting articles and religiously revising and reverting poor edits is really the only decent solution to the Frankenstein Syndrome problem. Speaking of which, I think that I'll go fix Kitten Huffing --Sir gwax (talk) 18:31, 22 February 2006 (UTC)
## A Noob Question!
I am a noob here. I already have experience as a Wikipedia article-improver, but I possess little background knowledge when it comes to using the Wiki format and how to make the best of the tools at hand. I am here at the Village Dump because I have many questions, and from what I can tell, this is the place to ask them.
I need to learn how to:
1. indent text (such as when typing a poem, or numbered list like this one) 2. correctly insert graphics into an article 3. make use of my signature
Another problem:
A beloved new article that I wrote had a NRV stamp placed on it a while it was fresh. I improved it and I think the stamp should be removed. Should I remove it on my own, or must I somehow consult with the much esteemed admins first?
I need a little help, or I will continue to be an incompetent noob and most likely get myself banned, therefore robbing Uncyclopedia of a valuable resource.
1. Indents are made with a colon.
2. How to put an image in an article.
3. Click the signature button above the edit window.
As for the NRV template, I think you can remove it on your own if you've improved the article.--Sir AlexMW KUN PS FIYC 23:35, 18 February 2006 (UTC)
Removing the NRV tag by yourself could lead to a ban if done wrong; you would do well to follow the instructions on the NRV tag itself and read Uncyclopedia:Pages for deletion section 4.1 to make sure you do it right. --Sir gwax (talk) 19:58, 22 February 2006 (UTC)
## Those Crazy Frenchies
So, I've just been to Paris for a few days, and even in freezing February, it's as charming as ever. But it seems that the spirit of Uncyclopedia just won't leave me alone wherever I go. When the girlfriend and I went out to eat on the first evening, we picked a nice looking little bistro not far from the Seine, went in, opened the menu - and the first thing I saw was this. Trying to explain our fits of laughter to the waiter would have been nigh-on impossible ("Qu'est que ce, l'Uncylopédia?"), but I can reveal to you that "Un Andoillette AAAAA" is a very tasty sausage stuffed with mixed meats. One more thing (and I am aware that hearing about other people's holidays is deadly boring) - we also made the pilgrimage to Pére Lachaise Cemetary on behalf of all you Uncyclopedians to pay our respects to the founder himself.
“It's a nice enough place to be buried; if only the neighbours weren't all bloody French.”
~ Oscar Wilde
-- Sir Codeine K·H·P·B·M·N·C·U·Bu. · (Harangue) 19:13, 18 February 2006 (UTC)
## Top10
Discussion WAS going on here. But we moved it to the dump.
So, should articles that were featured in 2006 but written mostly in 2005 stay in the list or not?--Rataube 18:50, 17 February 2006 (UTC)
• Yes. We don't need to be too strict. We are here for the fun. It was fun to vote for uncyclopedian of the year 2004 when in fact uncy wasnt created until 2005. I say any article featured before the creation of this page can stay.--Rataube 18:50, 17 February 2006 (UTC)
• No. In the interest of keeping this going, I think feature date is a good cut-off. If we are to have top ten of 2006, we need to make a distinction. --KATIE!! 18:53, 17 February 2006 (UTC)
• Comment: 1) This would make it so that only featured pages could be eligable. Right now the rules on the page allow notable pages that were not featured, the features are just all up for simplicity. 2) We didn't plan ahead this year, so it isn't too unfair to make this year have 13 months. Next year can still be from the current cutt-off date to December 31st without any problem. -- 00:45, 18 February 2006 (UTC)
• No. Use the feature date as the cut-off. ~ T. (talk) 19:23, 17 February 2006 (UTC)
• YES: The cutoff should be articles featured before the creation of this page. It is simplest and fairest that way. -- 23:42, 17 February 2006 (UTC)
• No. We need a Top10/2005 list and a Top10/2006 list......and next year a Top10/2007.....that way it can be formatted as part of bigger section, AND in the case of 2006 be ongoing over the next year. -- 23:44, 17 February 2006 (UTC)
• Yesh I don't see a big problem with having a 14-month Best Of this year and only a 10-month Best Of for 2006, and it's easiest to organize this way. --—rc (t) 23:59, 17 February 2006 (UTC)
• Hell no!! Just doesn't make sense. --⇔ 00:04, 18 February 2006 (UTC)
• Feature! It's not that big of a deal.
00:04, 18 February 2006 (UTC)
• No. I'm with Mhaille. Let's set this up to be easy to navigate for years to come.-- 15:10, 19 February 2006 (UTC)
• No, for the sake of consistency. --Algorithm (talk) 23:04, 19 February 2006 (UTC)
• Yes, since it wasn't elgible the year it was written. --Keithhackworth MUN F@H 13:40, 20 February 2006 (UTC)
[3] Could someone clean up the first 63? ---- 20:09, 17 February 2006 (UTC)
Number 65 too.--Rataube 20:14, 17 February 2006 (UTC)
I think Wikipedia decided that for Liscening reason they probably couldn't remove usernames, I'm guessing the same applies as we use a similiar type of liscence.--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 12:38, 20 February 2006 (UTC)
Licensing should only be an issue if they have contributions which haven't already been deleted (and for which they deserve credit/attribution). I suspect they don't. --Carlb 15:41, 20 February 2006 (UTC)
## Making up ******** Quotes
Recently, the question of deleting all of the Making Up Someone-or-other Quotes Pages came up on Uncyclopedia:VFD, but I figured this was a bigger, more general question and should be brought up somewhere a little higher traffic. So, what do you folks think, do we want this sort of thing on Uncyclopedia?
Making up Sun-Tzu quotes
Making up God quotes
Making up Cthulhu quotes
Making up Family Guy quotes
Making up Matrix quotes
Making up Anonymous quotes
Making up February 3rd quotes (NRV'd 2/15)
Making up Oscar Wilde quotes
Making up Winston Churchill quotes
Making up Christopher Walken quotes
Making up Mark Twain Quotes
Making up Noel Coward quotes (WIP)
Making up Star Trek quotes
Making up Thomas Jefferson Quotes
Making up Arthur C. Clarke quotes
Making up Benjamin Franklin quotes
Making up Albert Einstein quotes
Personally, I think the whole idea is rubbish. --Sir gwax (talk) 19:38, 16 February 2006 (UTC)
That is tough! Because I like a few of them a lot, and most of them not at all. Maybe we should just not feature them on the front page anymore... Except Cthulhu, since I voted for it.--Claudius Prime 20:35, 16 February 2006 (UTC)
I think we need to keep all the ones I did, and Some User will probably agree that his need to be spared. And I wouldn't want to be the soul who deleted Cthulhu's. Most are excellent/good/salvagable, the rest like Feb 3rd should be huffed as part of quality control. -- 21:27, 16 February 2006 (UTC)
See crons comments re:lists below, I think the same applies.--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 23:29, 16 February 2006 (UTC)
Seems to me there has been a real effort to fix these up lately. I say that the good ones should be kept and that some user should be empowered to kill the ones no one feels like fixing. -- 23:33, 16 February 2006 (UTC)
Clean out the worthless ones and turn the quality ones into HowTo: articles. » Brig Sir Dawg | t | v | c » 00:16, 17 February 2006 (UTC)
Ehh, I thought about writing a really long-winded tome about this, but basically it all boils down to what Mhaille said: All of these pages should stay or go based on their own individual merits. I'll suspend my efforts to "spruce up" the rest of them until this is resolved, but I wouldn't be sad to see the ones I haven't spruced up yet get deleted, and even a couple that I have (Twain and Einstein, to be specific). Also, I'm not asking for any special treatment or authority WRT these pages (but thanks for the suggestion, Isra), and it doesn't much matter to me if the titles are "Making up so-and-so quotes" or "QuoteUnquote:So-and-so," or whatever. I just don't want to throw out the baby with the bathwater. Basically it's your call, Gwax - put them all on VFD if you feel that strongly about it, but at least put them all there as individual entries, not as one big block. I'll support whatever the community decides. c • > • 00:48, 17 February 2006 (UTC)
I for one am not a huge fan of these quote pages, and no one has ever put a gun to my head and said that I had to participate if I wanted to be on Uncyclopedia or else. But just because I don’t haunt them doesn’t mean that they lack merit, nor do they by their existence have such great power that ruin my expirience with the site. And if they exist on Uncyclopedia and I never visit them, what do I care if they flourish or not? I have a real problem with decisions that discount the work of others simply because someone else thought of its first, etc, or maybe a genre is getting stale, etc.
Hell, not every article is going to be a humdinger, but why is there a rush to control creativity? Six out of seven “Making Up Famous Quote Pages” maybe the worst tripe in the world, but are we as a community so confident in ourselves that we will rule an entire class out without wondering if just maybe there is someone who hasn’t heard of the site and would otherwise be able to pull something great out the “Quotes” format? And besides, these things are like fads, they have natural cycles and they’ll fade as soon as the next catchy format pops up. I think we all need to remind ourselves that we were once new around here, and that something keeps us coming back and that’s the opportunity to create.
So I say let it die a natural death if its meant to die and lets focus on making this a great site through our contributions and not by slamming the door on creativity in content. Dame 02:45, 17 February 2006 (UTC)
Turn them into Uncyclopedia:QuoteUnquote pages, or kill them all. In fact, I'll try to remember to do that next week. 03:35, 17 February 2006 (UTC)
QuoteUnQuote looks like a rather half-baked ambitious project considering the complete lack of interest in it. Why don't you just leave the good ones as they are? -- 04:33, 17 February 2006 (UTC)
I dunno, I actually think Famine has the right idea. In fact, why don't we just "huff" the entire website? You know, clean slate, new broom, everything nice and neat and tidy, easy to manage and control. There'd certainly be a lot less for people to vandalize, and since nobody would want to write any new material (or "spruce up" old stuff) for fear of having the same thing eventually happen to that, we could all spend more time chatting, since that's what we all do best anyway! I vote for. Uhhh, that's assuming we're actually voting... - - c • > • 04:52, 17 February 2006 (UTC)
The only reason I put these all on VFD originally is that the whole "making up ____ quotes" is getting old and there are way too many of them. It was funny the first couple times, then they just became annoying knock-offs, much like aaaaa, zzzzz, yyyyy, etc. I agree, let's rate them individually. I would suggest keeping Oscar Wilde due to the dedicated template, and the whole "stick a Wilde quote on every page initative". I can see keeping God and Cthulhu quotes (let people choose the God they want). The others need to be huffed in my opinion. --User:Keithhackworth/sig2
Depending on the lvl of humour I think the Making up X quotes where X=Famously quotable person should be default stay (if only because it may supply inspiration for someone if they are not 100% funny already) the others should live or die on their merits alone.--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 14:52, 17 February 2006 (UTC)
I've been waiting for this for a while, actually. I think that the majority fo the MUXQ pages need to be killed outright. It's really a shame that the fact that there are so many of these pages is indicative of the lack of creativity of many of our users. I agree with Keeping some of the more outlandish and classic MUXQ pages (as Keith stated), but I definitely agree all the rest need to go.--Sir Flammable KUN (Na Naaaaa...) 18:45, 17 February 2006 (UTC)
CONCLUDING: Good ones stay, obviously bad ones get quickly euthanized, those in the middle or that we are not sure to where they belong get individually judged at VFD. I think that's the implicit agreement--Rataube 19:12, 17 February 2006 (UTC)
### but what of the quotes themselves?
We do appear to end up with many unfunny made-up quotes being plastered onto seemingly every page in the Uncyclopaedia - not just the "Google says George Bush doesn't care that Kayne West is going to f-ing kill Steve Ballmer" nonsense, but more often just quotes which really add nothing to the articles on which they are placed. Perhaps part of the problem is the sheer number of quotes being added - they needn't be applied like cheap perfume, in massive quantities long beyond the point where adding more of them has become counterproductive. They get boring rather quickly. Unfortunately, to clean this up now would mean selectively editing hundreds of pages.
What to do with this fine mess? --Carlb 01:05, 18 February 2006 (UTC)
If it makes life easier I've voluteer to "take care" of the Quotes section, just like RC does with VFP and VFH. Obviously that doesn't restrict others from contributing to what is in the section, just means that someone is personally chraged with keeping it in order. Aye? --
### Making up Nerd42 quotes
I have become known as one of the biggest advocates of Making up Quotes pages in general. I look at this part of the site as being no different from UnNews or what used to be UnDictionary. It's supposed to go like this:
Uncyclopedia = Wikipedia
UnNews = Wikinews
UnDictionary = Wikitionary
UnQuote = Wikiquote
If making up fake quotes on Uncyclopedia is limited to Oscar Wilde, then I think the entire shebang needs to be moved to it's own wiki, as there seems to be more than enough interest in the activity. (judging by the number of edits that quotes pages get) If this entire project is shut down, I would appreciate it if some Uncyclopedia admins would inform Wikicities that Making up Quotes is no longer allowed on Uncyclopedia so that if/when I suggest starting an UnQuote wiki, there will be no doubt as to whether Uncyclopedia already does this or not.
Either it's OK to do it, or it's not. That is not to say that each of the pages shouldn't be judged on an individual basis. But that's not what's happening here, is it? I see them being judged as a group. -- 05:39, 21 February 2006 (UTC)
Not they are not, almost everyone agreed that they have to be judged individually, and that's what is goin on, see VFD--Rataube 04:25, 23 February 2006 (UTC)
The people voting no seem to be judging them as a group, or that's what I'm trying to say. They're being nominated for VFD as a group, and the discussion seems to be over whether the type of article should be allowed or not. (as a group) Oh, um ... I am not saying any rules are being broken here ... man, everything I say seems to have all these implications I don't mean for it to have ... :(
Why aer people trying to get these pages deleted anyway? Alot of people seem to like them, so why do other people want to delete them so much? -- 01:09, 24 February 2006 (UTC)
I'll try to answer this as best I can, though I'm not sure an answer is really called for. There are currently five separate VFD entries, and while some of us have voted to delete all five, your suggestion that the pages are being "judged as a group" there is completely unfounded. They are being judged as a group here, and the fact that three of the most influential administrators on the site have used phrases like "kill 'em all," "the whole idea is rubbish," and "all the rest need to go" is disturbing, even if it's completely understandable from an historical perspective. But this isn't a question of what's "allowed" and what isn't; it's simply a matter of how the site should be organized, and how we're going to maintain quality standards.
Either way, the reason people want to delete those five pages is the same one that applies elsewhere: because they suck. I happen to believe that some of the people voting to keep them are doing so because they're fans of Family Guy or Star Trek (or whatever), and to delete the related "Making up quotes" page would be like deleting Star Trek itself somehow - which is silly, but maybe that's how people think. I don't know precisely. I just know that trying to make anything funny out of Star Trek is beyond my capability, and nobody else was doing much with it either, pretty much since the page first came into existence. Same with the others. Unless that changes in the next couple of days, I say delete 'em; they'll never meet the standards I've set (all modesty aside, of course) for the others. To those who disagree, you have my sincerest apologies. c • > • 02:40, 24 February 2006 (UTC)
## Uncyclopedia's Top 10
We could vote for the 10 bestest besst articles of 2005. Opinions?--Rataube 17:05, 16 February 2006 (UTC)
It's a good idea, but it might be kinda hard to organize, with the admins approval I could probably whip something up pretty quick. It'd be like PHP except it'd start blank and would be for articles instead of pictures. 17:08, 16 February 2006 (UTC)
Here. Feel free to make modifications, especially in the directions part. 17:36, 16 February 2006 (UTC)
Good idea. A couple things:
1. For simplicity's sake, I think we should disallow Against votes. I'm guessing that was your idea anyway, but it should probably be in the instructions at the top.
2. How to choose which articles are included on the list? For example, Zen was created in 2005, but so far this year it's been significantly edited. We could go by feature date, but that would exclude a good chunk of pages that were probably formed in 2005. Or we could just leave all of them in and not worry about it.
Once you're finished with it I suppose we could move it to Uncyclopedia: Best of 2005 or something. --—rc (t) 18:40, 16 February 2006 (UTC)
For simplicity's sake, I think it would be best just to allow all of them. But it doesn't really matter either way I guess. I'll add something about no against votes, and yea I was planning just for but it's a good idea to be very specific i guess. And once again, feel free to do these things yourself. Heh. 18:54, 16 February 2006 (UTC)
I agree with u that any article featured before the creation of the page can be there. But Mhaile and Keitei don't. We should decide that over here.--Rataube 19:02, 17 February 2006 (UTC)
## So are we gonna change the main page or what?
I know that ther's already a topic down there some where, but i think people pretty much forgot all about it. I think it's about time we get serious about changing it. Even though wikipedia hasn't yet, it'd be funny if we did it before them, because then we could pretend they stole it from us. Anyway, yea... should we take a vote or something? 16:56, 16 February 2006 (UTC)
"Editing will continue through Saturday, February 18th, inclusive. The final election will start on March 1st and will run for 3 weeks. In between we will have a period to rest, make further refinements,and test out the draft for bugs on different browsers, resolutions, screen sizes, et cetra."
So we still have some time if they stick to this. I agree we should change ours before they do. It'd be funny and I like the new page format much better, except for the Featured Image box being below the others (in their draft, at least). --—rc (t) 18:44, 16 February 2006 (UTC)
I've already got several versions to choose from, but I have been making more as en.wp has changed their draft. I think we can wait a while, still, but i encourage you to make comments on the drafts' talk pages. -- 22:32, 16 February 2006 (UTC)
I think we should change soon. Their draft actually looks pretty good. ~Sir Rangeley GUN WotM UotM EGA +S (talk) 23:50, 16 February 2006 (UTC)
OURS ARE BETTER!!! 23:53, 16 February 2006 (UTC)
## Forum, part 2
Okay, so working off of Chron's ideas, I've hacked up a new version of DynamicPageList that supports forum formatting, and created a sample implementation here. I could use some help coming up with a good look-and-feel for the layout and sections. Once it looks good, I think we can start using it here. What do you all think? --Algorithm (talk) 00:13, 16 February 2006 (UTC)
You know how on recent changes there is the button that lets you set a time and then after that, it only shows edits made after that specified time? Can something like that be done with this so that only threads that have been changed after time X will be bolded, or something like that? -- 01:36, 16 February 2006 (UTC)
And how will this work with watchlists?-- 01:38, 16 February 2006 (UTC)
I'm not certain whether your first suggestion will work or not, but I'm looking into it. As for the watchlists, they won't work on the forum listings; you'll have to watch each topic individually. I might be able to jury-rig the listings to update themselves whenever they're rendered, but even then it wouldn't trigger until someone viewed the listing. --Algorithm (talk) 01:54, 16 February 2006 (UTC)
It's great, but I still think we should remain open-minded and have a vote when all possible ideas are put in. I'll set up an Invisionfree forum as a preview, and someone with experience with phpBB should also provide a sample. --officer designate Lugiatm 09:26, 16 February 2006 (UTC)
I'll do that. --— 16:53, 16 February 2006 (UTC)
I like this, this is exactly what would be nice. --Chronarion 07:27, 19 February 2006 (UTC)
## Greatest Men Ever to Live Equals Dumbest Category
An unregistered user (84.248.223.42) is slapping, what I feel to be, yet another useless category/template onto article after article without actually contributing to anything. It looks like this-
{{GreatestMen}}
I'm I alone in thinking we have enough categories? On some biographies there is already five or six categories and now this template is creating more junk...
Give me your feedback users...--Claudius Prime 20:34, 15 February 2006 (UTC)
I agree. --Spin 21:27, 15 February 2006 (UTC)
My only complaint is that J.D. Salinger is not on that list. -- 22:05, 15 February 2006 (UTC)
Looks useless to me. I vote you can kill it. -- 22:13, 15 February 2006 (UTC)
Done. ~ T. (talk) 23:09, 15 February 2006 (UTC)
Take the category back, clean it and merge it with the article. The category was there long before the template. We'd rather have categories like this one than list-articles. If they are not spammed they make no harm.--Rataube 16:11, 16 February 2006 (UTC)
At this point, a list which duplicates an existing category adds nothing that couldn't be autogenerated (hint: DynamicPageList) so is hardly worth creating. --Carlb 23:17, 18 February 2006 (UTC)
## Charmed, I'm sure
What a purrrrfectly wonderful diversion this Uncyclopedia is for the casual browser. Anyone care to show me around? Faster Pussycat Kill Kill 20:20, 15 February 2006 (UTC)
Uncyclopedia:Best of for (some) good stuff. See here for everything else. --—rc (t) 20:23, 15 February 2006 (UTC)
I reccomend Pot v. Kettle and J.D. Salinger. And this page is a repository for the best stuff on Uncyclopedia. -- 22:12, 15 February 2006 (UTC)
Heh heh. Don't you ever feel lonely on the inside? 16:18, 16 February 2006 (UTC)
## MY FAMILY!!!
THIS IS AN EMERGENCY, I REPEAT, AN EMERGENCY. RATAUBE HAS KIDNAPPED MY FAMILY!!! I don't know what happened... he just all of the sudden snapped! Out of nowhere! At first they were just empty threats, but now he's doing it for real!! He's out of control, he took my family and left a note on my talk page!! Oh whatever shall I do??!?! I love my family with all of my heart. PLEASE HELP ME!
(The original ransom note can be found here.}
00:57, 15 February 2006 (UTC)
The World's Tiniest String Quartet. Shown under an electron microscope. Scale is 100 pixels per Ångstrom. They are playing My Heart Bleeds for You.
--— 01:00, 15 February 2006 (UTC)
## Artistic Nude Sophia
Everyone knows that Sophia was a porn actress before she founded Uncyclopedia. Well, now I think all the admins fancy her a little bit and so somebody has made a picture of what he thinks she'd look like naked. This is good for all you potential logo makers who like reskinning, but not good for Splarka who has to add all future logos in the site coding. This image was used a base for images like Zombiepedia, so you can get a good idea of the sexiness. The image is ALREADY THE RIGHT SIZE. There is enough room at the bottom for text, which ZB has reliably informed me is Bookman Old Style, 16 pt, strong, regular. With 24-pt U and A. or 22.8pt, small caps, capital U and A. --officer designate Lugiatm 12:01, 14 February 2006 (UTC)
This was my only clean pair of pants. Thanks a lot.... --Spin 01:28, 15 February 2006 (UTC)
Lugi: I consulted Moneysign. He'd made that as a bigger file to make it easier to edit. Since you resized it and made it a PNG, it should at least match the current logo... so I uploaded the blank one I'd made for Image:Aaaa.png over it (it has the precise hue and proportions, Money's was based on Image:Puzzle_Potato_Large.png). I also added it to Nihilism. --Splaka 07:18, 15 February 2006 (UTC)
Heck, I uploaded the image Splarka's referring to so people have a choice. (read: so I can extend my gallery) --⇔ 07:34, 15 February 2006 (UTC)
I didn't realize uncyclopedia's logo is a potato until I was told, thought it was just some kind of twisted puzzle. Is it just me?--Rataube 13:17, 15 February 2006 (UTC)
Nope...lots of people have said that. Apparently it also looks like an egg. :\ --—rc (t) 15:05, 15 February 2006 (UTC)
Same here. At first I thought it was just a really weird shaped version of the Wikipedia logo. --OsirisX 06:58, 16 February 2006 (UTC)
Me too. Perhaps if Sophie had potato "eyes"? --User:Keithhackworth/sig2
Yeah, I originally thought the logo was just a deflated, browned Wikipedia logo. -- neoEva88 MUN F@H PS CM NS (talk.to-do)
We had a 3d-tater before, if anyone wants to digg that up. --Chronarion 07:30, 19 February 2006 (UTC)
Wait a second ... so the potato's name is Sophia? I thought Sophia was a lady on the telly from the 1950s -- 05:43, 21 February 2006 (UTC)
It's also the greek word for knowldege. philosophy = knowldege love or potato madness--Rataube 04:28, 23 February 2006 (UTC)
## Lists
In fact, while I'm thinking about it, are we sure that the anti-list policy is quite right? There are some contexts in which lists can be fantastically useful (ex. United States Presidents). It occurs to me that perhaps a different policy is in order, more along the lines of crappy lists should be treated like all other crap, pages containing good lists should be named "List of...", where "..." is replaced with content. Or do you peoples like the anti-list policy or some other version of things? --Sir gwax (talk) 05:58, 13 February 2006 (UTC)
As usual, there's no blanket policy on this. Really crap lists are removed, and the idea is that it shouldn't eat up the whole page. Things that were really bad include "List of people god hates", which inevitably sounded like a phone book. So, the bad lists die, and if they're any good, they're kept.--Chronarion 06:02, 13 February 2006 (UTC)
Well, I suppose a namespace could be a possiblity for really good ones.
## Facts
Until recently, Chuck Norris, Vin Diesel and Mr. T had long lists of so called "facts" on them. As a result of admin views and vague Uncyclopedia policies, these lists were deleted (primarily because they were only minorly original and they were great big lists (we don't like lists)) and there has been a rather forceful attempt to squelch reposts. However, there has been some discussion on the talk pages and it seems to be the case that we may very well have been the Internet's best source for Chuck Norris facts and a lot of people really liked them. To this end, I put forth, for your consideration, the idea of creating Chuck Norris/Facts (and co.) as a means of keeping the facts in Uncyclopedia but preventing them from clogging Chuck Norris (and co.) with more than a single link. What do you folks think? --Sir gwax (talk) 05:53, 13 February 2006 (UTC)
Split the page then. There's little harm in that, but lists are rarely pruned, which is where one of the problems lie. --Chronarion 06:03, 13 February 2006 (UTC)
I don't have a big problem with having a seperate page for facts. The problem is when people just copy and paste facts from the random Chuck Norris/Vin Diesel/Mr. T facts generator. Uncyclopedia is not a humor repository, it is a source for original satire. If people are going to make up their own funny facts, I don't see a problem with creating a new subpage for it. ----24.222.232.42 20:02, 13 February 2006 (UTC)
The lists are hilarious, original or not. They need to be somewhere and Uncyclopedia is a good place for them. If it makes things easier, put them on a seperate page. --OsirisX 02:06, 14 February 2006 (UTC)
HOLD ON. A majority of Chuck facts were written a LONG, LONG, LONG time ago as Vin Diesel facts. We need to make sure none of those wind up on the lists. --[[User:Nintendorulez|Nintendorulez | talk]] 17:00, 15 February 2006 (UTC)
• Wouldn't it be more likely that the "Internet's best source for Chuck Norris facts" might be http://www.chucknorrisfacts.com/ -- or did they steal their facts from us? It's like a chicken-and-egg question (though we already know the answer to that one). -- Sir BobBobBob ! S ? [rox!|sux!] 01:00, 16 February 2006 (UTC)
## Do we need a "Vanity" Namespace
As we have added a couple of namespaces recently, I'm wondering if we should have a Vanity space, to more clearly differentiate rabid-fanboy pages from the rest of this site. A user randomly clicking through our site and stumbling across a flame-filled page of user-lists from a message board they've never heard of is probably not going to be all that impressed. As per the "keep the site not shit" rule, clearly differentiating the non-article/non-content pages from the rest of our content might improve the overall feel of the site. In addition, from an admin standpoint, while they would need to be directed there initally, we could more easily ignore some of the flamey page edits if they were contained to their own little corner. 16:15, 12 February 2006 (UTC)
I wish we could, but we've received a directive from on high to allow articles on fansites and such. Regarding the vanity namespace, I'm of two minds. On one hand it would certainly be nice to set vanity apart from the rest of Uncyc, but giving it its own namespace almost seems like encouragement. Perhaps we could make it Garbage: or Fanboy:. --—rc (t) 20:26, 12 February 2006 (UTC)
If it's funny, keep it. If it's really lame, burn it. It's not a blanket exception. --Chronarion 04:39, 13 February 2006 (UTC)
But who decides what's funny in these cases? Personally, I'm pretty sure I won't find anything about a Power Rangers vanity site page funny, but I'm sure it hilarious to them. --—rc (t) 06:18, 13 February 2006 (UTC)
Admins, pretty much. The thing is that if it's at least MOSTLY readable and well written, it can stay, i.e. steam forums, which was amusing. If it's like RangerBoard... --Chronarion 07:31, 19 February 2006 (UTC)
Don't get too rabid please. Someone marked 4chan "vanity" when it's only tangentially about the website and is actually about network geeks - David Gerard 00:13, 13 February 2006 (UTC)
## How Not To Write an Article
I've noticed a trend amongst a number of people when discussing whether or not an article should be deleted; namely, I've noticed that every once in a while someone suggest keeping a complete shit article because it's a great example of how not to write an article or, it's so completely terrible they think it's funny. Personally, I hate this and it really pisses me off. That noted, however, I'm not the sort to go and trash stuff other people want to keep for the wrong reasons just because I think it's crap. In order to try to appease others and still provide a means for getting rid of this kind of drek, I propose the creation of a new namespace for articles that are so bad, we want them kept (something like BadExample: WrongCrowd: Crap: HowNotToWriteAnArticle: or such). Examples of things that I think should be handled in this way are Cunt cunt cunt cunt crap crap shit, Fisher Price and a whole bunch of other such things. --Sir gwax (talk) 21:27, 9 February 2006 (UTC)
Well, rcmurphy would never agree to this. Apparently some actual, non-IP users find this crap funny. Although Cunt cunt cunt cunt crap crap shit is funny. Reminds me of Woof, Meow, Developers!, etc. --[[User:Nintendorulez|Nintendorulez | talk]] 22:11, 9 February 2006 (UTC)
And the commentaries on cunt cunt and Fisher-price are hilarious. Though, I don't think we need a namespace for this. We only need ONE article. Perhaps something like Uncyclopedia:How Not to Write an Article. --[[User:Nintendorulez|Nintendorulez | talk]] 18:34, 11 February 2006 (UTC)
I wholeheartedly support Gwax's proposal. I suggest namespace "Anti-humor:" -- 22:31, 9 February 2006 (UTC)
I'm gonna go with Isra's name. Sounds good to me. 22:34, 9 February 2006 (UTC)
I hereby pledge my support to "Anti-humor."-- 22:57, 9 February 2006 (UTC)
I'd support a category for this kind of thing, but certainly not a namespace. The presence of a namespace implies wide-scale approval, and I think we want to limit this type of inanity to a dozen pages or so. --Algorithm (talk) 04:16, 10 February 2006 (UTC)
2nd that. ~ T. (talk) 01:28, 12 February 2006 (UTC)
3rd. I admit, I laughed myself sick at the Fisher Price retrospective, and even Cunt^4 got a few chuckles out of me. Crass vulgarity can work sometimes, if the subject material is taken as serious art. However, I think that these things do need to be kept segregated from the general population and closely monitored. A category would allow this, but a namespace, like Algorithm said, might encourage more asanine behavior (as I feared in my comments on Fisher Price's VFD nomination.) --The King In Yellow (Talk to the Dalek.) 18:01, 13 February 2006 (UTC)
## That bastard Stephen Colbert.
IDEA ALERT: We should have an anti-Colbert reskinning, "attacking" him and such. That would put the issue right at the forefront. We get a lot of lurkers who just come to read and link stuff to their blogs, and they might not see the village dump. Who up for it???-- 00:36, 7 February 2006 (UTC)
Agreed, and then we should spam his inbox with screenshots. Yes, yes indeed. 00:40, 7 February 2006 (UTC)
I disagree. A reskin is too much, but there should be SOMETHING that mentions this on the front page. Maybe under Chron's State of the Wiki?00:53, 7 February 2006 (UTC)
Idea sounds good, but we don't nesicarily have to do a re-skinning, we could always just put the Colbert article on IC and then make it a feature article.--Jsonitsac 15:55, 7 February 2006 (UTC)
Come on, people. This has to be OVER THE TOP for it to get noticed and for it to work. That means a well-done reskinning and a well-done front page parody. -- 20:57, 7 February 2006 (UTC)
See, for those who have never watched the Colbert Report, he is really, really, REALLY, REALLY, REALLY... [infinite recurrance of reallys] ...over the top. Really. So, if we are going to make fun of him, we have to imitate his style, and a loony reskin would suit the idea perfectly. --[[User:Nintendorulez|Nintendorulez | talk]] 19:41, 9 February 2006 (UTC)
you know, stephen did appear in newsweek recently. maybe we could involve them somehow.--Jsonitsac 23:31, 7 February 2006 (UTC)
It seems like nothing more than blatant reference begging to me. We'd be walking the ED-esque-attention-whore-tight-rope, but if you think you can pull something off and make it suitably outrageous and funny, best of luck. --S P I N N I E 05:12, 8 February 2006 (UTC)
I think we can. All we have to do is get noticed and mentioned somewhere. A newspaper would be best. Case in point: a girl who won a drawing contest with a picture of Colbert got some airtime. Tons of other times Colbert has mentioned references to himself in the media. BUT THIS ISN'T ABOUT THE PUBLICITY!!1!11! It's about DEFENDING our RIGHTS to TRUTH! And stuff. I have a really awful first draft which is completely half-assed, but it's the general idea. If somebody can put together a nice new anti-Colber logo and uber-patriotic front page, I'd love to do the words. We can put Colbert to JUSTICE!!! -- 14:11, 8 February 2006 (UTC)
Interesting start, but it needs a lot of work, like big pictures of the american flag, eagles, swastikas, and professional graphics to make it work. Maybe large U shapes all over the place? And the Word of the Day should be Wørd of The Day, or even Wørd øf the Day.--Jsonitsac 17:01, 8 February 2006 (UTC)
His Word last night was Jesi. Bastard ripped the plural of Jesus right from Uncyclopedia. Who do we call to sue? I think that we should seriously mount a (good-natured, unless you were thinking otherwise?) email campaign. Who knows, maybe we could get some airtime... -- 00:37, 2 February 2006 (UTC)
Well, the first step would be to make a page, methinks...--Bradaphraser 00:41, 2 February 2006 (UTC)
Ok, now that that's done, how's about a slander campaign on the article to try to get on his show?--Bradaphraser 00:45, 2 February 2006 (UTC)
I always knew he was up to no good. We need to start an email campaign as soon as possible. Ready set go. 02:30, 2 February 2006 (UTC)
Here's an email adress to the Colbert Nation: webmaster@colbertnation.com --Jsonitsac 02:56, 2 February 2006 (UTC)
Don't we have a pretty open license though? --Sir gwax (talk) 16:32, 2 February 2006 (UTC)
Yer but it's for non-comercial likesy init (I guess the beeb could use it then?)--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 00:05, 3 February 2006 (UTC)
Wow. I was pretty pissed on IRC last night to know that I missed Colbert Report, but to know that I missed such a monumental word? Although seriously, Jesii isn't exactly property of Uncyclopedia. It's the plural of Jesus. It's like trying to copyright "the", or "You're fired". --[[User:Nintendorulez|Nintendorulez | talk]] 17:00, 2 February 2006 (UTC)
Jesii is absolutely not the correct plural. In fact, it is possibly the most wrong, more wrong than: Jesi, Jesera, Jesora, Jesa, Jesuses, Jessen, Jesies, Jesuss, Jesus's, Jesus', Jesoes, Jesuves, Jesices, Jesum, Jesantes, Jesta, Jesux, Jesot, Jesuit, etc. For one thing, it is in the wrong declension to go i -> us, for another, only ius words become ii, eg: Radius -> Radii. The most technicaly correct plural of Jesus is Jesus. But that isn't funny. Jesii is. --Splaka 22:50, 2 February 2006 (UTC)
That man is a coward, and unless he admits it on the air, he's only proving my point. And since we're stealing from each other, you sir, are dead to me. - Nonymous 00:07, 3 February 2006 (UTC)
I believe that church of subgenius has been using Jesii for a while. --Chronarion 06:04, 7 February 2006 (UTC)
Stealing from Uncyclopedia... that's like taking candy from a mentally handicapped baby. Doug 04:49, 8 February 2006 (UTC)
Here's what I sent to the webmaster@colbertnation.com address:
Subj: Please Direct This To Mr. Colbert (PLAGIARIZER) Immediately!
Mr. Colbert,
Last night while viewing your show, I was left in shock and awe when you said that your Word was "Jesi", or a plural form of Jesus. Then I saw your smug little grin, and I could tell that you thought that you had thought up this word just like how you "made up" the word "truthiness" (nice try).
Well I have news for you. uncyclopedia.wikia.com, a very fine organization dedicated to spreading the REAL truth, invented the plural for Jesus long ago. Observe: http://uncyclopedia.wikia.com/wiki/Template:Jesii
Now I know what you're thinking. "But I spelled it with one 'i', not two!" Very clever, Mr. Colbert. But we can see right through your subterfuge (see? I can make up words too). You're trying to steal our possessions, alter them, and then sell them off as your own. I know the biz; I worked as a bootlegger in Hong Kong for 12 years. But this isn't Hong Kong, my friend. This is America.
I, as well as the rest of my many friends at Uncyclopedia, concur that if you do not address and apologize for the fact that you stole from us ON AIR... you're a coward.
-- 01:52, 3 February 2006 (UTC)
Just added the first official Wilde/Ballmer quote on that Comedy Central website.--Jsonitsac 15:28, 3 February 2006 (UTC)
I accidenly got drunk tonight, and just as accidently caught this particluar episode in re-run mode. My hands hurt from the extended run of obscene gestures I made to the TV for the stealage of Jesi, even if it was spelled wrong. We must strike back. With Great Vengence. 03:50, 17 February 2006 (UTC)
Yes, but let's wait til we're all sober. 03:54, 17 February 2006 (UTC)
## The biggest dicks on uncyc
Created and posted by request of Splaka. Here are the relative sizes of our estimed admins' members as measured in deletions:
-- 08:53, 6 February 2006 (UTC)
Mine is finally big enough for autofellatio! Bah. --Splaka 09:02, 6 February 2006 (UTC)
God, I am ashamed at my lack of effort in the last few months. But really...I deleted 500 articles in one day during Forest Fire Week...how is it possible that I only have 1500 deletions? What time-frame are you looking at here? Regardless, it looks like it's time for me to go list, NRV, stub, and orphan hunting. By the end of the month my goal is to clear 2000 deletions, minimum. 00:49, 7 February 2006 (UTC)
Time frame for "length" is since the begining. Time frame for "girth" is from your first deletion to the time the chart was made. -- 01:14, 7 February 2006 (UTC)
Finally, some sort of stats to help with my withdrawal symptoms. :) Now... how 'bout them edit counts? :) ~ T. (talk) 01:05, 7 February 2006 (UTC)
I'm a little disappointed that the day people decide to make a measurement of each other's "old man" coincides with the weekend when I'm dying of the flu. Oh, and it was cold. -- 01:16, 7 February 2006 (UTC)
God....Keitei has more girth than I do...now that's depressing. Guess it's time to switch from Kiss posters to something else... 01:39, 7 February 2006 (UTC)
Famine, if you're slimming down, it's because you haven't been eating again! --Carlb 05:34, 7 February 2006 (UTC)
I lost over a month of deletions and I've had trouble keeping up for a while...just too much to do outside of the site. I wish I could delete more. » Brig Sir Dawg | t | v | c » 05:39, 7 February 2006 (UTC)
Whwne will you all learn thats it's not the number of deletions that counts but what you have deleted!!--The Right Honourable Maj Sir Elvis UmP KUN FIC MDA VFH Bur. CM and bars UGM F@H (Petition) 11:07, 7 February 2006 (UTC)
You have a point there. People like Famine have like 10 times the quality of deletes that Splaka has, since he's deleted crap like the Main Page before. » Brig Sir Dawg | t | v | c » 13:52, 7 February 2006 (UTC)
True, but we expect to see a certain level of deletion, suffering and mayhem in the wake of one of the Four Norsemen of the Apocalypse. --Carlb 19:23, 7 February 2006 (UTC)
Isra needs to make new stats. I just went on a deletion spree! If it isn't nailed down and doesn't have someone defending it, it's burning! » Brig Sir Dawg | t | v | c » 11:34, 8 February 2006 (UTC)
Ok, I admit it..I'm the scrawniest, weakest of the horsemen. About the only thing I can defeat them at is a pie-eating contest. 00:01, 8 February 2006 (UTC)
Mind you, Pestilence comes back from the ratrace looking tired and haggard at times too. Not to worry... --Carlb 11:55, 10 February 2006 (UTC)
How can mine be smaller than Keitei's!?! Well.....you guys got me --Nytrospawn 19:07, 19 February 2006 (UTC)
## Worst 100 Reflections on the Year
Once this reaches a full 100, we should make it an official article. -- 03:13, 10 February 2006 (UTC)
Done. --Zyrac 18:40, 20 February 2006 (UTC)
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2015-11-30 22:01:02
|
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https://zenodo.org/record/2480265/export/csl
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Conference paper Open Access
# Towards a Deep Unified Framework for Nuclear Reactor Perturbation Analysis
Fabio De Sousa Ribeiro; Francesco Caliva; Dionysios Chionis; Abdelhamid Dokhane; Antonios Mylonakis; Christophe Demaziere; Georgios Leontidis; Stefanos Kollias
### Citation Style Language JSON Export
{
"publisher": "Zenodo",
"DOI": "10.5281/zenodo.2480265",
"language": "eng",
"title": "Towards a Deep Unified Framework for Nuclear Reactor Perturbation Analysis",
"issued": {
"date-parts": [
[
2018,
11,
21
]
]
},
"abstract": "<p>In this paper, we take the first steps towards a novel unified framework for the analysis of perturbations in both the Time and Frequency domains. The identification of type and source of such perturbations is fundamental for monitoring reactor cores and guarantee safety while running at nominal conditions. A 3D Convolutional Neural Network (3DCNN) was employed to analyse perturbations happening in the frequency domain, such as an absorber of variable strength or propagating perturbation. Recurrent neural networks (RNN), specifically Long Short-Term Memory (LSTM) networks were used to study signal sequences related to perturbations induced in the time domain, including the vibrations of fuel assemblies and the fluctuations of thermal-hydraulic parameters at the inlet of the reactor coolant loops. 512 dimensional representations were extracted from the 3D-CNN and LSTM architectures, and used as input to a fused multi-sigmoid classification layer to recognise the perturbation type.</p>",
"author": [
{
"family": "Fabio De Sousa Ribeiro"
},
{
"family": "Francesco Caliva"
},
{
"family": "Dionysios Chionis"
},
{
"family": "Abdelhamid Dokhane"
},
{
"family": "Antonios Mylonakis"
},
{
"family": "Christophe Demaziere"
},
{
"family": "Georgios Leontidis"
},
{
"family": "Stefanos Kollias"
}
],
"id": "2480265",
"event-place": "Bengaluru, India",
"type": "paper-conference",
"event": "IEEE Symposium Series on Computational Intelligence (SSCI 2018)"
}
52
75
views
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2022-12-06 09:43:47
|
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|
https://de.zxc.wiki/wiki/Gleichgewicht_(Systemtheorie)
|
# Equilibrium (systems theory)
In the general sense, a system is in equilibrium if it does not change over time without external influence. In the case of dynamic equilibria , only macroscopic changes are generally considered. In a thermodynamic equilibrium , for example, the macrostate of a gas with the state variables pressure , temperature and chemical potential is constant, while the microstate , i.e. the position and speed of individual gas particles, can change.
The state that the system does not leave without external influence is generally called the state of equilibrium , critical point , fixed point , stationary state , equilibrium position . Depending on the context, the terms mentioned are not used synonymously, but contain an additional classification of the state, for example with regard to stability. When considering open systems , an unchanging state is referred to as a “steady state”, while the term “equilibrium” is used for a stationary state after the system has been isolated .
## general definition
First, a closed dynamic system is considered . The state of a dynamic system at the point in time can generally be described by a tuple, i.e. an ordered set of all state variables. In order for the state to be a state of equilibrium, it must be the same for all times, one also says "invariant to a dynamic ". ${\ displaystyle t}$${\ displaystyle x \ in \ mathbb {R} ^ {n}}$${\ displaystyle f}$
The position and number of states of equilibrium in a system is independent of the state in which the system is, i.e. also independent of whether it is "in equilibrium" or not. The states of equilibrium result as solutions of the equilibrium conditions. Depending on the number of solutions of the equations for the respective equilibrium condition, a system can have any number of equilibrium states.
### Continuous dynamic system
Example of a one-dimensional system. The x -axis is the state space; the black arrows show the evolution of time. The two zeros of the function f are the equilibrium states x 1 and x 2 . The function f can be a potential of the negative gradient e represent.
For a continuous dynamic system whose time evolution is given by the differential equation
${\ displaystyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} x = f (x)}$
a state of equilibrium is given by the equilibrium condition ${\ displaystyle x (t) = x ^ {*}}$
${\ displaystyle f (x ^ {*}) = 0}$
since then the time derivative is accordingly . A state of equilibrium is therefore a time-independent solution of the ordinary differential equation or a zero of the function . ${\ displaystyle \ textstyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} x ^ {*} = 0}$${\ displaystyle f}$
### Discrete dynamic system
Convergence to a steady state in a discrete-time macroeconomic stock-flow consistent model .
A discrete dynamic system, which only allows discrete time steps, can be represented by an iterated mapping
${\ displaystyle x_ {n + 1} = f (x_ {n}), \ qquad n = 0,1,2 \ ldots}$
describe. The equilibrium condition for the state of equilibrium is ${\ displaystyle x_ {n} ^ {*}}$
${\ displaystyle x_ {n} ^ {*} = f (x_ {n} ^ {*}).}$
The equilibrium point is therefore a time-independent fixed point in the mapping . ${\ displaystyle x_ {n} ^ {*}}$${\ displaystyle f}$
### State of equilibrium and potential
Instead of looking at the zeros of the function , a potential can be found for many systems , so that it can be written as a negative gradient of the potential. A state of equilibrium then corresponds to an extreme point of the potential. In a thermodynamic system , this is a suitable thermodynamic potential . For example, for a system at constant temperature and pressure, such as a chemical reaction, the Gibbs free enthalpy is suitable , which is minimal when the system is in thermodynamic equilibrium. ${\ displaystyle f}$ ${\ displaystyle E}$${\ displaystyle f = - \ nabla E}$
In a Hamiltonian system, the state can be described by the position coordinates and impulses . For a state of equilibrium, and . The dynamics are given by the canonical equations . Insertion of the equilibrium condition shows that in a state of equilibrium the partial derivative of the Hamilton function and are zero, the state of equilibrium is therefore an extreme point of the potential. ${\ displaystyle x}$ ${\ displaystyle q_ {i}}$ ${\ displaystyle p_ {i}}$${\ displaystyle \ textstyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} q_ {i} = 0}$${\ displaystyle \ textstyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} p_ {i} = 0}$ ${\ displaystyle \ textstyle {\ frac {\ mathrm {d} H} {\ mathrm {d} p_ {i}}}}$${\ displaystyle \ textstyle {\ frac {\ mathrm {d} H} {\ mathrm {d} q_ {i}}}}$
In mechanics, the location with the coordinates of the equilibrium is also called the position of rest or static position of rest . In particular, a particle does not experience any force in the rest position. “Rest position” is somewhat misleading in this respect: Although there is no force acting on a particle in the rest position, the particle does not have to be at rest there. Only in a static state in which the equilibrium condition is also fulfilled for the impulses is the particle there at rest and the system in equilibrium. ${\ displaystyle q_ {i}}$
## Behavior of equilibria in the event of disturbances
The development of a dynamic system over time can be estimated qualitatively by characterizing the states of equilibrium. A state of equilibrium can be roughly divided into
stable
The system returns to its original state after a fault.
unstable
The system changes to another state in the event of the slightest disturbance.
indifferent
The system comes to rest in a new state after each fault.
metastable
After a sufficiently large disturbance, the system changes to a more stable state of equilibrium. In the case of two states of equilibrium, one also speaks of bistable .
There are several stability terms in stability theory for the mathematically exact classification . In the following a continuous system is assumed; similar terms can also be defined for systems with discrete time steps.
Lyapunov stable
An equilibrium state is Lyapunov stable if a sufficiently small error condition will remain small or precise: For each there is a such that for all times and all trajectories with the following applies: .${\ displaystyle x ^ {*}}$${\ displaystyle \ varepsilon> 0}$${\ displaystyle \ delta> 0}$${\ displaystyle t \ geq 0}$${\ displaystyle x (t)}$${\ displaystyle \ | x (0) -x ^ {*} \ | <\ delta}$${\ displaystyle \ | x (t) -x ^ {*} \ | <\ varepsilon}$
asymptotically stable
A state of equilibrium is asymptotically stable if it is Lyapunov-stable and attractive, i.e. if it returns to the state of equilibrium in the event of a disturbance. Attractive means that there is one out there, so that each trajectory with all exist and the condition fulfilled.${\ displaystyle x ^ {*}}$${\ displaystyle \ eta> 0}$${\ displaystyle x (t)}$${\ displaystyle \ | x (0) -x ^ {*} \ | <\ eta}$${\ displaystyle t \ geq 0}$${\ displaystyle \ lim _ {t \ to \ infty} x (t) = x ^ {*}}$
One method of stability analysis is to linearize the system around the state of equilibrium . With the Hartman-Grobman theorem , the equilibrium state can then be characterized using the eigenvalues of the Jacobi matrix .
## Examples
### Thermal equilibrium in a house
The time course of the temperature in an unheated house as a function of the outside temperature can be shown in a simple model using the differential equation ${\ displaystyle T}$${\ displaystyle T _ {\ mathrm {A}}}$
${\ displaystyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} T = -k (T-T _ {\ mathrm {A}})}$
describe. The constant is calculated from the area , the heat transfer coefficient of the house walls and the heat capacity of the air. The function on the right side of the equation determines the dynamics of the system. For a state of equilibrium , ${\ displaystyle k = A \ alpha / C}$${\ displaystyle A}$ ${\ displaystyle \ alpha}$ ${\ displaystyle C}$${\ displaystyle f (T) = - k (T-T _ {\ mathrm {A}})}$${\ displaystyle T ^ {*}}$
${\ displaystyle f (T ^ {*}) = - k (T ^ {*} - T _ {\ mathrm {A}}) = 0}$.
The system has a state of equilibrium at . Because the derivative ${\ displaystyle T ^ {*} = T _ {\ mathrm {A}}}$
${\ displaystyle {\ frac {\ mathrm {d} f} {\ mathrm {d} T}} (T ^ {*}) = - k}$
is negative, the equilibrium state is stable. If the house is warmer or colder than the surroundings, it cools or warms up until it reaches this state of equilibrium. In this way, by determining the equilibrium points and their stability, statements about the behavior of the system can be made without having to explicitly calculate the temperature curve over time . The integration of the equation, which would be necessary for this explicit calculation, is generally not easy or not analytically possible in non-linear systems. ${\ displaystyle T ^ {*}}$${\ displaystyle T (t)}$
### Mechanical equilibrium in a plane pendulum
A level pendulum as a ride at a fair
Equilibrium positions of the plane pendulum.
Phase space of the plane pendulum with constants = 1. The potential and the phase space are periodic with period 2π with respect to the angle θ.
A plane pendulum is a mechanical system in which a mass is rotatably attached to a point with a pendulum rod of fixed length . The state of such a pendulum at a fixed point in time can be described by an angle and the angular velocity . The equation of motion is then the autonomous differential equation${\ displaystyle l}$${\ displaystyle \ textstyle x = (\ theta, \ omega)}$${\ displaystyle t}$${\ displaystyle \ textstyle \ theta \ in [0,2 \ pi)}$ ${\ displaystyle \ textstyle \ omega \ in \ mathbb {R}}$
${\ displaystyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} {\ begin {pmatrix} \ theta \\\ omega \ end {pmatrix}} = {\ begin {pmatrix} \ omega \ \ {\ frac {g} {l}} \ sin \ theta \ end {pmatrix}}}$
where the constant is the gravitational acceleration . ${\ displaystyle g}$
The system thus has two equilibrium points and , which meet the equilibrium condition. The equilibrium point at an angle of zero is the stable equilibrium when the pendulum has no deflection and speed. The second point is the unstable equilibrium when the pendulum has no speed and is "upside down". In phase space there is an elliptical fixed point , the point a hyperbolic fixed point . ${\ displaystyle x_ {1} = (0,0)}$${\ displaystyle x_ {2} = (\ pi, 0)}$${\ displaystyle x_ {1}}$${\ displaystyle x_ {2}}$${\ displaystyle x_ {1}}$${\ displaystyle x_ {2}}$
In a static system, i.e. a system in which the pendulum has no speed , the condition for mechanical equilibrium can be formulated with the help of forces and moments . The pendulum is in equilibrium when the sum of all acting forces and moments is zero. In both equilibrium points and , the weight of the mass on the pendulum is completely balanced by the force with which the pendulum rod holds the mass at the pivot point. The resulting force and moment are zero. ${\ displaystyle x_ {1}}$${\ displaystyle x_ {2}}$
### Ecological balance in a predator-prey relationship
Phase space of the Lotka-Volterra system with constants = 1
A simple model of the interaction between predator and prey populations is the Lotka-Volterra equations . They describe the development over time of a number of prey animals and predators . With the respective reproduction and death rates or and or , the differential equation system results for a state : ${\ displaystyle N_ {1}}$${\ displaystyle N_ {2}}$${\ displaystyle \ epsilon _ {1}}$${\ displaystyle \ gamma _ {2}}$${\ displaystyle \ gamma _ {1}}$${\ displaystyle \ epsilon _ {2}}$${\ displaystyle x = (N_ {1}, N_ {2})}$
${\ displaystyle {\ frac {\ mathrm {d}} {\ mathrm {d} t}} {\ begin {pmatrix} N_ {1} \\ N_ {2} \ end {pmatrix}} = {\ begin {pmatrix } N_ {1} \ left (\ epsilon _ {1} - \ gamma _ {1} N_ {2} \ right) \\ - N_ {2} \ left (\ epsilon _ {2} - \ gamma _ {2 } N_ {1} \ right) \ end {pmatrix}}}$
The system has a stable equilibrium point and an unstable equilibrium point . The state has a constant number of predators and prey that are in ecological equilibrium . In the state , both populations are wiped out. ${\ displaystyle x_ {1} = (\ epsilon _ {2} / \ gamma _ {2}, \ epsilon _ {1} / \ gamma _ {1})}$${\ displaystyle x_ {2} = (0,0)}$${\ displaystyle x_ {1}}$${\ displaystyle x_ {2}}$
## Dynamic equilibria
A system in nature can generally be described in different ways. There are differently detailed possibilities to choose the state variables of the system. In statistical physics, the terms macrostate and microstate are used to differentiate between differently detailed descriptions . In the case of equilibrium considerations, such as a thermodynamic equilibrium, only the macrostate is considered. The system is in equilibrium if the macrostate does not change. However, the microstate of the system can change.
If there are processes within the system or flows across the system boundaries that change the microstate, cancel each other out in their influence on the macrostate of the system, an equilibrium is called dynamic equilibrium or steady state .
### Dynamic equilibrium in a closed system
In the case of non-open systems, it is only internal processes that influence the state variables of the system. The equilibrium condition formulated above is fulfilled in systems of chemical reactions exactly when the chemical potentials are balanced. Example: A thermally insulated pressure pot with hot water and steam. The two reactions involved are evaporation and condensation. Evaporation lowers the temperature and increases the pressure, which slows down further evaporation or accelerates condensation. After some time, an equilibrium is established in which both reactions proceed at the same speed and the state variables pressure, temperature and amount of steam remain constant.
For systems in dynamic equilibrium, the virial theorem applies in the respective sub-area of physics. Explicit knowledge of orbits is not required for this.
### Quasi-static changes in state
In general, there are more than two reactions that happen at the same time. The equilibrium can then exist between all participating elements of the system or it can be limited to a subsystem. If the processes of the subsystem are fast compared to exchange processes with the environment, then quasi-static changes of state occur. Example: The slowly cooling pressure pot. The release of heat to the environment lowers the temperature, the pressure and the amount of steam, but not independently of one another, rather the system state always remains close to the steam pressure curve .
Whether there is a separation into fast and slow processes in a special case and how the changes in the state variables occur over time is the subject of kinetics .
### Fluid equilibria in open systems
If there are several coupling processes with the environment, the state of the system can remain constant in that they cancel each other out more or less randomly. Dynamic equilibria are always associated with the production of entropy , which must be removed for a steady state.
#### Tight coupling
If a coupling process dominates the other processes, the state of the subsystem is defined in the affected state variable. Examples: The pot is open, the pressure is set to atmospheric pressure, even high heating power does not raise the temperature above the boiling point as long as there is still water in the pot. In electrical engineering, the voltage is fixed ( clamped ) when a small consumer is connected to a voltage source . An economic example is fixed book prices (for works without an alternative, such as special books).
#### Flow equilibrium in the reaction-free system
Without close coupling, systems will usually react to changes in the environment with significant changes in their state. The term steady state suggests the following example: The level of a tub without stopper is located at a given inflow as level adjustment that the level is dependent on the outflow is equal to the inflow. But there are also constant equilibria with many other physical and non-physical quantities, such as energy or wealth.
#### Homeostatic balance
The flows across the system boundary can also be balanced out by the system influencing them through internal control processes. The system theory generally calls the subsystem of a complex system that forms the control mechanism homeostat , the prototypical example is the thermostat .
The term homeostasis was coined in connection with living systems in which many system parameters are usually subject to regulation: pH value, osmotic pressure, enzyme concentrations, temperature, number of cells - to name just a few.
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2023-02-05 20:53:44
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https://labs.tib.eu/arxiv/?author=O.B.%20Shchegolev
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• ### Characteristics of EAS neutron component obtained with PRISMA-32 array(1612.09460)
Dec. 30, 2016 astro-ph.IM, astro-ph.HE
The paper is devoted to the results of the EAS neutron component investigations by means of the PRISMA-32 array. The array consists of 32 en-detectors and enables to record delayed thermal neutrons accompanying showers. For registration of thermal neutrons, the scintillator based on $^{6}Li$ isotope as a target is used in the detectors. Some results of the processing of data accumulated over a long period of time are presented: the lateral distribution function of neutrons in EAS and preliminary results on EAS neutron multiplicity spectrum and distribution of showers in e/n ratio.
• ### Detection of thermal neutrons with the PRISMA-YBJ array in Extensive Air Showers selected by the ARGO-YBJ experiment(1512.01326)
We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and $^{6}$LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector.
• ### Barometric pumping effect for radon-due neutron flux in underground laboratories(1605.01283)
It is known that neutron background is a big problem for low-background experiments in underground Laboratories. Our global net of en-detectors sensitive to thermal neutrons includes the detectors running both on the surface and at different depths underground. We present here results obtained with the en-detector of 0.75 m^2 which is running more than 3 years in underground room at a depth of 25 m of water equivalent in Skobeltsyn Institute of Nuclear Physics, Moscow. Spontaneous increases in thermal neutron flux up to a factor of 3 were observed in delayed anti-correlation with barometric pressure. The phenomenon can be explained by a radon barometric pumping effect resulting in similar effect in neutron flux produced in (alpha,n)-reactions by alpha-decays of radon and its daughters in surrounding rock
• ### EAS thermal neutron lateral and temporal distributions(1512.02042)
A novel type of EAS array (PRISMA-32) has been constructed on the base of NEVOD-DECOR experiment (MEPhI,Moscow) and is now taking data. It consists of 32 specially designed scintillator en-detectors able to measure two main EAS components: hadrons (n) and electrons (e). First results on thermal neutron lateral as well as temporal distributions are presented. Obtained exponential neutron lateral distributions are consistent with that expected for normal hadron production with exponential transverse momentum distribution. As there are no other experimental data on thermal neutron distributions and so, to compare results with other measurements, we additionally obtained electron lateral distribution function (using the same detectors) and compared it with NKG - function. Recorded neutron temporal distributions are very close to that obtained with data of our previous prototypes.
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2021-04-12 15:51:11
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https://istopdeath.com/find-the-exact-value-sin1-1/
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Find the Exact Value (sin(1))/1
Divide by .
Evaluate .
The result can be shown in multiple forms.
Exact Form:
Decimal Form:
Find the Exact Value (sin(1))/1
Scroll to top
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2022-11-30 20:21:42
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https://en.wiktionary.org/wiki/covering_number
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# covering number
1. (graph theory) The number of vertices in a minimum vertex cover of a graph, often denoted as ${\displaystyle \tau =\tau (G)}$.
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2017-12-17 10:13:06
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http://nrich.maths.org/public/leg.php?code=12&cl=2&cldcmpid=91
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Search by Topic
Resources tagged with Factors and multiples similar to Maze 100:
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There are 143 results
Broad Topics > Numbers and the Number System > Factors and multiples
What Do You Need?
Stage: 2 Challenge Level:
Four of these clues are needed to find the chosen number on this grid and four are true but do nothing to help in finding the number. Can you sort out the clues and find the number?
Eminit
Stage: 3 Challenge Level:
The number 8888...88M9999...99 is divisible by 7 and it starts with the digit 8 repeated 50 times and ends with the digit 9 repeated 50 times. What is the value of the digit M?
Becky's Number Plumber
Stage: 2 Challenge Level:
Becky created a number plumber which multiplies by 5 and subtracts 4. What do you notice about the numbers that it produces? Can you explain your findings?
Zios and Zepts
Stage: 2 Challenge Level:
On the planet Vuv there are two sorts of creatures. The Zios have 3 legs and the Zepts have 7 legs. The great planetary explorer Nico counted 52 legs. How many Zios and how many Zepts were there?
Crossings
Stage: 2 Challenge Level:
In this problem we are looking at sets of parallel sticks that cross each other. What is the least number of crossings you can make? And the greatest?
Which Is Quicker?
Stage: 2 Challenge Level:
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
Three Dice
Stage: 2 Challenge Level:
Investigate the sum of the numbers on the top and bottom faces of a line of three dice. What do you notice?
Being Determined - Primary Number
Stage: 1 and 2 Challenge Level:
Number problems at primary level that may require determination.
Mathematical Swimmer
Stage: 3 Challenge Level:
Twice a week I go swimming and swim the same number of lengths of the pool each time. As I swim, I count the lengths I've done so far, and make it into a fraction of the whole number of lengths I. . . .
Remainders
Stage: 3 Challenge Level:
I'm thinking of a number. When my number is divided by 5 the remainder is 4. When my number is divided by 3 the remainder is 2. Can you find my number?
Always, Sometimes or Never? Number
Stage: 2 Challenge Level:
Are these statements always true, sometimes true or never true?
GOT IT Now
Stage: 2 and 3 Challenge Level:
For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?
Three Neighbours
Stage: 2 Challenge Level:
Look at three 'next door neighbours' amongst the counting numbers. Add them together. What do you notice?
Abundant Numbers
Stage: 2 Challenge Level:
48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?
Factor Lines
Stage: 2 and 3 Challenge Level:
Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
Three Times Seven
Stage: 3 Challenge Level:
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Divide it Out
Stage: 2 Challenge Level:
What is the lowest number which always leaves a remainder of 1 when divided by each of the numbers from 2 to 10?
Hot Pursuit
Stage: 3 Challenge Level:
The sum of the first 'n' natural numbers is a 3 digit number in which all the digits are the same. How many numbers have been summed?
Factor-multiple Chains
Stage: 2 Challenge Level:
Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?
Tom's Number
Stage: 2 Challenge Level:
Work out Tom's number from the answers he gives his friend. He will only answer 'yes' or 'no'.
Round and Round the Circle
Stage: 2 Challenge Level:
What happens if you join every second point on this circle? How about every third point? Try with different steps and see if you can predict what will happen.
Stage: 3 Challenge Level:
Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .
AB Search
Stage: 3 Challenge Level:
The five digit number A679B, in base ten, is divisible by 72. What are the values of A and B?
Spelling Circle
Stage: 2 Challenge Level:
Find the words hidden inside each of the circles by counting around a certain number of spaces to find each letter in turn.
Flashing Lights
Stage: 2 Challenge Level:
Norrie sees two lights flash at the same time, then one of them flashes every 4th second, and the other flashes every 5th second. How many times do they flash together during a whole minute?
Ben's Game
Stage: 3 Challenge Level:
Ben passed a third of his counters to Jack, Jack passed a quarter of his counters to Emma and Emma passed a fifth of her counters to Ben. After this they all had the same number of counters.
Ip Dip
Stage: 1 and 2 Challenge Level:
"Ip dip sky blue! Who's 'it'? It's you!" Where would you position yourself so that you are 'it' if there are two players? Three players ...?
Neighbours
Stage: 2 Challenge Level:
In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
Multiply Multiples 1
Stage: 2 Challenge Level:
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
Multiply Multiples 2
Stage: 2 Challenge Level:
Can you work out some different ways to balance this equation?
Got it for Two
Stage: 2 Challenge Level:
Got It game for an adult and child. How can you play so that you know you will always win?
Multiply Multiples 3
Stage: 2 Challenge Level:
Have a go at balancing this equation. Can you find different ways of doing it?
Tiling
Stage: 2 Challenge Level:
An investigation that gives you the opportunity to make and justify predictions.
Three Spinners
Stage: 2 Challenge Level:
These red, yellow and blue spinners were each spun 45 times in total. Can you work out which numbers are on each spinner?
Number Tracks
Stage: 2 Challenge Level:
Ben’s class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?
Multiplication Series: Number Arrays
Stage: 1 and 2
This article for teachers describes how number arrays can be a useful reprentation for many number concepts.
What's in the Box?
Stage: 2 Challenge Level:
This big box multiplies anything that goes inside it by the same number. If you know the numbers that come out, what multiplication might be going on in the box?
Being Collaborative - Primary Number
Stage: 1 and 2 Challenge Level:
Number problems at primary level to work on with others.
Thirty Six Exactly
Stage: 3 Challenge Level:
The number 12 = 2^2 × 3 has 6 factors. What is the smallest natural number with exactly 36 factors?
Scoring with Dice
Stage: 2 Challenge Level:
I throw three dice and get 5, 3 and 2. Add the scores on the three dice. What do you get? Now multiply the scores. What do you notice?
Ewa's Eggs
Stage: 3 Challenge Level:
I put eggs into a basket in groups of 7 and noticed that I could easily have divided them into piles of 2, 3, 4, 5 or 6 and always have one left over. How many eggs were in the basket?
Divisively So
Stage: 3 Challenge Level:
How many numbers less than 1000 are NOT divisible by either: a) 2 or 5; or b) 2, 5 or 7?
Path to the Stars
Stage: 2 Challenge Level:
Is it possible to draw a 5-pointed star without taking your pencil off the paper? Is it possible to draw a 6-pointed star in the same way without taking your pen off?
Diggits
Stage: 3 Challenge Level:
Can you find what the last two digits of the number $4^{1999}$ are?
Gaxinta
Stage: 3 Challenge Level:
A number N is divisible by 10, 90, 98 and 882 but it is NOT divisible by 50 or 270 or 686 or 1764. It is also known that N is a factor of 9261000. What is N?
What Is Ziffle?
Stage: 2 Challenge Level:
Can you work out what a ziffle is on the planet Zargon?
Repeaters
Stage: 3 Challenge Level:
Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.
X Marks the Spot
Stage: 3 Challenge Level:
When the number x 1 x x x is multiplied by 417 this gives the answer 9 x x x 0 5 7. Find the missing digits, each of which is represented by an "x" .
Oh! Hidden Inside?
Stage: 3 Challenge Level:
Find the number which has 8 divisors, such that the product of the divisors is 331776.
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2017-01-20 16:05:16
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https://zbmath.org/?q=an:1361.65076
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## Runge-Kutta convolution quadrature and FEM-BEM coupling for the time-dependent linear Schrödinger equation.(English)Zbl 1361.65076
Summary: We propose a numerical scheme to solve the time-dependent linear Schrödinger equation. The discretization is carried out by combining a Runge-Kutta time stepping scheme with a finite element discretization in space. Since the Schrödinger equation is posed on the whole space $$\mathbb{R}^d$$, we combine the interior finite element discretization with a convolution quadrature based boundary element discretization. In this paper, we analyze the resulting fully discrete scheme in terms of stability and convergence rate. Numerical experiments confirm the theoretical findings.
### MSC:
65M38 Boundary element methods for initial value and initial-boundary value problems involving PDEs 35Q41 Time-dependent Schrödinger equations and Dirac equations 65M60 Finite element, Rayleigh-Ritz and Galerkin methods for initial value and initial-boundary value problems involving PDEs 65M20 Method of lines for initial value and initial-boundary value problems involving PDEs 65L06 Multistep, Runge-Kutta and extrapolation methods for ordinary differential equations 65M12 Stability and convergence of numerical methods for initial value and initial-boundary value problems involving PDEs
Full Text:
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2022-12-06 01:38:45
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http://202.116.86.88/main/news/CommonNews.aspx?ColumnNo=NA03&NewsNo=d540e20c-6165-423d-a495-e467249d4a1a
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------------------------------ ѧԺ̬ ѧγ ѧѶ ѧ ѵƽ̨ ------------------------------ ɽѧ>> ͨƽϵͳ>> ɽѧѧ>>
ǰλã ѧԺҳ > ѧѶ >
ѧ棨IJʿ :ǿ ʱ:2016-8-15 15:27:05 Ķ:424 ĿԳȱ2άγ ʿ ѧϵ ʱ201681815:30-16:30 صѧ¥415 ժҪWe consider intersecting codimension-two supersymmetric defects in 4d N=2, 5d N=1 supersymmetric gauge theories defined on a manifold M. The intersection of defects can be defined by introducing localized degrees of freedom supported on the codimension-four intersection locus. We compute the partition function of the 4d/2d/0d coupled system. In a simplest example, we identify the partition function with the dual Liouville four-point correlation function (with a generic degenerate insertion). We also extract the same partition function from the Higgs branch localization point of view, which gives the geometric interpretation of the defect gauge theories as the worldvolume theories of the Seiberg-Witten solutions on C2. As a byproduct, it leads to a neat factorization of the instanton partition function into two vortex partition functions. ˼ƱҵɽѧϵŦԼʯϪУʿѧλѧϵ²ʿҪоռϵijԳƹ淶ۣԳȱԼصļ⡣ԳռȫεϵԳȱڵľȷɽԼ 4 ά $\mathcal{N} = 2$, 5 ά $\mathcal{N} = 1$ 淶 2 ά Liouville/toda ۵ϸӦϵ ӭʦμ! ѧѧԺ 2016/8/15 һ:ѧѧ棨ͳɳɣһ:ѧ棨Ժʿ
ȨУɽѧѧѧԺ ͨѶַк¸·135ɽѧѧ¥266 ʱࣺ510275 ֧֣ΰʱϢVins
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2017-04-27 16:45:06
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https://plainmath.net/9622/subspaces-suppose-that-prove-that-linearly-independent-nonzero-vectors
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# Let U,V be subspaces of Rn. Suppose that U⊥V. Prove that {u,v} is linearly independent for any nonzero vectors u∈U,v∈V.
Let U,V be subspaces of Rn. Suppose that $$U\bot V.$$ Prove that $$\{u,v\}$$ is linearly independent for any nonzero vectors $$u\in U,\ v\in V.$$
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• Get a detailed answer even on the hardest topics.
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Pohanginah
Given that $$U\bot V$$ that is $$(u, v) = 0$$ for any $$u\in U$$ and $$v\in V$$. Let
$$au+bv=0$$
$$\Rightarrow(au+bv,u)=0 \Rightarrow a(u,v)+b(u,v)=0 \Rightarrow a(u,u)=0$$ (since u is a non zero vector) $$\Rightarrow a=0$$
Again
$$au+bv=0 \Rightarrow (au+bv,v)=0 \Rightarrow a(u,v)+b(u,v)=0 \Rightarrow b(v,v)=0$$ (since v is a non zero vector) $$\Rightarrow b=0$$
Therefore $$\displaystyle{a}{u}+{b}{v}={0}\to{a}={b}={0}$$. Hence $$\{u,v\}$$ is linearly independent.
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2021-12-01 23:45:35
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https://brilliant.org/discussions/thread/help-with-statistics/
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×
# Help with Statistics!!!
Let x¯, M and σ^2 be respectively the mean mode and variance of n observations x1, x2 ,....., xn and di = (−x1−a) ,i=1,2,.....,n, where a is any number. Statement I : Variance of d1,d1,.....,dn is σ2 Statement II : Mean and mode of d1,d2,.....,dn are −x¯−a and -M-a, respectively
Note by Ashley Shamidha
2 years, 5 months ago
Sort by:
As for the case of mode, there is nothing difficult to understand. You see, if the observations $${ x }_{ 1 },{ x }_{ 2 },...,{ x }_{ n }$$ have frequencies $${ f }_{ 1 },{ f }_{ 2 },...,{ f }_{ n }$$, then obviously the observations $$(-{ x }_{ 1 }-a),(-{ x }_{ 2 }-a),...,(-{ x }_{ n }-a)$$ must have the same set of frequencies, and thus if the r-th x value has the highest frequency, then the r-th d value will have the same, i.e., will be the mode. Now, $${ d }_{ ir}=(-{ x }_{ r }-a)=-M-a$$ which shows why the mode is (-M-a). Now, for the mean calculation, we have $\bar { d } =\frac { \sum _{ 1=1 }^{ n }{ { d }_{ i }{ f }_{ i } } }{ \sum _{ 1=1 }^{ n }{ { f }_{ i } } } =\frac { \sum _{ i=1 }^{ n }{ \left( -{ x }_{ i }-a \right) { f }_{ i } } }{ \sum _{ 1=1 }^{ n }{ { f }_{ i } } } =\frac { -\sum _{ i=1 }^{ n }{ { x }_{ i }{ f }_{ i } } -\sum _{ i=1 }^{ n }{ a{ f }_{ i } } }{ \sum _{ 1=1 }^{ n }{ { f }_{ i } } } =\frac { -\bar { x } \sum _{ i=1 }^{ n }{ { f }_{ i } } -a\sum _{ i=1 }^{ n }{ { f }_{ i } } }{ \sum _{ i=1 }^{ n }{ { f }_{ i } } } =-\bar { x } -a$ Similarly we can calculate variance as below:${ \sigma }_{ d }^{ 2 }=\frac { \sum _{ i=1 }^{ n }{ { \left( { d }_{ i }-\bar { d } \right) }^{ 2 }{ f }_{ i } } }{ \sum _{ i=1 }^{ n }{ { f }_{ i } } } =\frac { \sum _{ i=1 }^{ n }{ { \left\{ \left( { -x }_{ i }-a \right) -\left( -\bar { x } -a \right) \right\} }^{ 2 }{ f }_{ i } } }{ \sum _{ i=1 }^{ n }{ { f }_{ i } } } =\frac { \sum _{ i=1 }^{ n }{ { \left( { x }_{ i }-\bar { x } \right) }^{ 2 }{ f }_{ i } } }{ \sum _{ i=1 }^{ n }{ { f }_{ i } } } ={ x }_{ d }^{ 2 }$The basic idea is very simple, in case of mode or mean, we are searching for a central representative value of the whole data set. So, if any change is made to the data variable (scale change and/or origin shifting, here multiplying by -1 and then adding -a respectively), the same change is expected to be reflected in the mean or mode value. But in case of variance, which is the measure of how much the values are dispersed from the central value, no origin shifting is reflected (in simple words, the a's get cancelled during taking the differences). Hope this helped you. · 1 year, 9 months ago
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2017-09-22 02:47:21
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http://www.hxkqyxzz.net/EN/10.7518/hxkq.2015.04.008
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### Effect of topically applied recombinant adenovirus of adiponectin on bone defect repair
Lü Xue, Liu Na, Du Wen, Li Jiayang, Sun Yue, Luo En
1. State Key Laboratory of Oral Diseases, Dept. of Orthognathic and Temporomandibular Joint Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
• Online:2015-08-01 Published:2015-08-01
Abstract:
Objective To investigate the effect of local administration of recombinant adenovirus of human adiponectin (hAPN) Ad-hAPN-EGFP on tibial defect repair of SD rats. Methods Tibial defect (2 mm) models of 36 SD rats (72 sides) were randomly divided into three groups (A, B, and C; n=24). The three groups were injected with Ad-hAPN-EGFP, Ad-EGFP, and normal saline, respectively, during operation and the day after operation. A week after the operation, the expression of hAPN and osteogenesis-related factors were detected by real-time polymerase chain reaction. Three weeks after operation, the tibias were examined by micro-computed tomography, hematoxylin-eosin staining, and Masson staining to evaluate the restoration of bone defects. Results 1) The hAPN expression was detected in group A but not in groups B and C. Osteogenesis-related factors expression of group A was significantly higher than that of the other groups (P<0.05). 2) Osteogenesis (including bone mineral density, relative bone volume, trabecular number and trabecular thickness) in group A were more evident than those in groups B and C (P<0.05). No significant differences were found between groups B and C (P>0.05). Conclusion Local administration of recombinant adenovirus Ad-hAPN-EGFP may be an effective strategy to improve the restoration of bone defects in vivo.
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2022-12-07 03:20:09
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https://hal.archives-ouvertes.fr/hal-00632597v2
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# Hyperbolic traveling waves driven by growth
* Corresponding author
2 NUMED - Numerical Medicine
UMPA-ENSL - Unité de Mathématiques Pures et Appliquées, Inria Grenoble - Rhône-Alpes
Abstract : We perform the analysis of a hyperbolic model which is the analog of the Fisher-KPP equation. This model accounts for particles that move at maximal speed $\epsilon^{-1}$ ($\epsilon>0$), and proliferate according to a reaction term of monostable type. We study the existence and stability of traveling fronts. We exhibit a transition depending on the parameter $\epsilon$: for small $\epsilon$ the behaviour is essentially the same as for the diffusive Fisher-KPP equation. However, for large $\epsilon$ the traveling front with minimal speed is discontinuous and travels at the maximal speed $\epsilon^{-1}$. The traveling fronts with minimal speed are linearly stable in weighted $L^2$ spaces. We also prove local nonlinear stability of the traveling front with minimal speed when $\epsilon$ is smaller than the transition parameter.
Keywords :
Document type :
Journal articles
https://hal.archives-ouvertes.fr/hal-00632597
Contributor : Vincent Calvez <>
Submitted on : Monday, November 21, 2016 - 9:39:24 AM
Last modification on : Tuesday, November 19, 2019 - 11:44:52 AM
Long-term archiving on : Monday, March 20, 2017 - 4:50:46 PM
### Files
telegraphe_revisedGregoireEmer...
Files produced by the author(s)
### Citation
Emeric Bouin, Vincent Calvez, Grégoire Nadin. Hyperbolic traveling waves driven by growth. Mathematical Models and Methods in Applied Sciences, World Scientific Publishing, 2014, 24 (6), http://www.worldscientific.com/doi/abs/10.1142/S0218202513500802. ⟨10.1142/S0218202513500802⟩. ⟨hal-00632597v2⟩
Record views
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2019-12-08 10:21:13
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https://codegolf.meta.stackexchange.com/questions/23743/language-of-the-month-for-august-2021-k
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# Language of the Month for August 2021: K
In accordance with our meta agreement, since one candidate received more votes than the others, we have a new featured language! Throughout August 2021, our Language of the Month will be:
# K
## What's a Language of the Month?
See the meta post for nominations. In short, during August, those who wish to participate should learn (at least the basics of) K, and use it to solve challenges. Participation is completely optional, but is anticipated to be fun!
K is a member of APL-family languages, originally created by Arthur Whitney. Arthur's K has many versions; the latest version as of June 2021 is Shakti (also commonly called K9), which is still under development.
While official K versions were made for commercial purposes, multiple open-source implementations are also available. Two actively maintained ones are oK by John Earnest (JohnE), and ngn/k. The oK manual is a particularly good resource to get started in K, and then you can choose to move to ngn/k without too much problem (the two are 99% compatible with each other). You can also ask any questions about programming in K in the k tree, where multiple open-source K implementors (including JohnE and ngn) and other K users are regularly active.
• It is the K language actually used in investment banks and hedge funds.
• It is a great example of iterations of language design, aimed at general purpose programming with a small set of built-in functions and easy-to-parse syntax. I'd especially recommend K to the CGCCers interested in making their own languages.
• The oK manual is an excellent resource for starters.
• Despite being relatively minimalistic in the list of built-ins (and being ASCII-only), K is often pretty competitive in code golf.
• K is also often pretty fast for an interpreted language.
## Bounty
I (Bubbler) will award a +100 bounty for any user's first K answer posted during this month. A user doesn't qualify if they have posted a K answer before.
# List of all K tips posted in August 2021
• add entries in the form:
[<tip title>](https://codegolf.stackexchange.com/a/<answer-ID>) by [username](https://codegolf.stackexchange.com/users/<user-ID>)
# List of K-related challenges posted in August 2021
• add entries in the form:
[<challenge title>](https://codegolf.stackexchange.com/q/<question-ID>) by [username](https://codegolf.stackexchange.com/users/<user-ID>)
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2021-09-16 18:20:54
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https://www.physicsforums.com/threads/charge-of-a-nucleus.130674/
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Charge of a nucleus
1. Sep 3, 2006
poteat86
Hi, this problem is killing me.
What is the total charge of the radon nucleus? (The neutral radon atom has 86 electrons.)
The units is in Coulombs so I figured since they were asking for the charge of just the nucleus then it would be 86 protons times -1.6x10^-19 C. But that didn't work, I've tried every answer I can think of but it isn't working. (its like an online hw thing...i have only a few tries left and i need this answer to continue the rest) Please please help!! Thanks!
2. Sep 3, 2006
poteat86
oh my god, sorry i didn't see that sticky about hw. I'll post somewhere else...sorry!
3. Sep 3, 2006
Staff: Mentor
-1.6x10^-19 C is the charge on an electron.
A proton is positively charged, and if there are 86 of them, then 86 * the charge of one proton is correct.
Be careful of + and -.
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2016-10-26 19:48:27
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https://stats.stackexchange.com/questions/166876/the-f-test-is-a-test-for-variance-so-why-do-we-use-f-test-in-anova?noredirect=1
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# The F-test is a test for variance so why do we use F-test in ANOVA? [duplicate]
To test the mean vector we use ANOVA, and to test two variances we use the F-test, but my question is in ANOVA why we do use the F-test ?
Our goal is to define an estimable quantity that will take on a known value (here 1 or close to 1) if the null hypothesis is true. By taking the ratio of sum of squares over degrees of freedom, we create an F distributed statistic. This is because given $$X_1 \sim \chi^2_{df1}, \,\,X_2 \sim \chi^2_{df2}$$ $$Y =\frac{X_1/df1}{X_2/df2}$$ Then $Y \sim F$.
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2020-01-18 15:07:18
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https://math.stackexchange.com/questions/2571189/how-to-find-this-binomial-summation
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# How to find this binomial summation
How to calculate this?$$\sum_{x = 0}^n \sum_{y = 0}^n a^x b^y\binom{x + y}{y}$$
I tried the following approach by replacing $x + y = t$ and then solving $\sum_{t\ =\ 0}^{2n}\sum_{r=max(0,\ t - n)}^{min(n,\ t)} a^r b^{t - r}\binom{t}{r}$ but this got me nowhere. Maybe we can reduce it to one summation instead of two which can be solved in $\mathcal{O(n)}$ time then?
Let's denote $S(t) = \sum_{r\ =\ max(0, t - n)}^{min(n, t)}a^rb^{t - r}\binom{t}{r}$. Now $\forall 1 \leq t \leq n,\ S(t) = (a+b)S(t - 1)$
So, for calculating $S(t),\ \forall t > n$ notice \begin{align*} S(n + 1) = (a+b)^{n+1} - \binom{n + 1}{0}a^{n + 1} - \binom{n + 1}{0}b^{n + 1}\\ S(n + 1) = (a + b)S(n) - \binom{n + 1}{0}a^{n + 1} - \binom{n + 1}{0}b^{n + 1} \end{align*} Now, using the identity $$\binom{n}{r} = \binom{n-1}{r - 1} + \binom{n}{r - 1}$$. We can write $S(n + 2)$ as \begin{align*} S(n + 2) = (a + b) * S(n + 1) - \binom{n + 2}{1}a^{n+1}b^1 - \binom{n + 2}{1}a^1b^{n + 1} \end{align*} Similarly, we can calculate $$S(i) = (a+b)S(i-1) - \binom{i}{i - n - 1}a^{n + 1}b^{i - n - 1} - \binom{i}{i - n - 1}b^{n + 1}a^{i -n - 1}$$ Hence, each time we are decreasing two appropriate terms after multiplying it $(a + b)$. This all works because of the identity stated above. Hence, you can calculate it all $S(i)$ in $\mathcal{O(n)}$ time.
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2019-06-20 19:39:00
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https://math.stackexchange.com/questions/1445511/directed-graph-where-some-vertices-are-blue-find-nearest-blue-vertex
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directed graph where some vertices are blue, find nearest blue vertex.
Let $G = (V; E)$ be a directed graph where some subset of the vertices are coloured blue and each edge has a non-negative length. Provide an $\operatorname{O}(|E| \log n)$ time algorithm for finding the length of the shortest path from each vertex in the graph to its nearest blue vertex.
My biggest problem is being able to do this in the specified time. I could go down all edges of the starting vertex, then down the edges of each of those vertices, until I find a blue vertex. And then when I find it, save the path. But that won't work because it won't be fast enough, so any help would be appreciated, thanks!
EDIT: Shortly after posting this, I realized I can use Dijkstra's Algorithm.
• Yes, adopt Dijkstra. The only trick is, it runs in $O(m + n \log n)$ only if you use Fibonacci Heaps... – gt6989b Sep 21 '15 at 20:04
• You should expand your edit and post it as an answer to your own question. That way this post doesn't go on the unanswered questions queue. – Mike Pierce Sep 21 '15 at 21:50
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2019-08-19 09:38:02
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http://mathoverflow.net/questions/126311/spaces-of-smooth-functions-with-bounds-on-partial-derivatives
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# spaces of smooth functions with bounds on partial derivatives
## EDIT: As there were no takers at all... I have added below a possible approach I came up with...
I would like to ask the following elementary but tricky question about the density of spaces of smooth functions.
We are given spaces $\mathcal{J}^{u,v}, \mathcal{K}^u, \mathcal{J}^v$ such that
$\bigcap_{(u,v) \in \mathbb{R}^2} \mathcal{J}^{u,v}(\mathbb{R}^{2l+2k}) = S(\mathbb{R}^{2l + 2k})$ and
$\bigcap_{u \in \mathbb{R}} \mathcal{K}^u(\mathbb{R}^{2l}) = S(\mathbb{R}^{2l})$,
$\bigcap_{v \in \mathbb{R}} \mathcal{J}^v(\mathbb{R}^{2k}) = S(\mathbb{R}^{2k})$.
QUESTION: The tensor product $\mathcal{K}^u \otimes \mathcal{L}^v \subset \mathcal{J}^{u,v}$ see below. Is this tensor product with the induced $C^{\infty}$ Fr\'echet topology dense?
DEFINITIONS:
Here $\mathcal{J}^{u,v}(\mathbb{R}^{2l + 2k}) \subset C^{\infty}(\mathbb{R}^{2l + 2k})$, $\mathcal{K}^u(\mathbb{R}^{2l}) \subset C^{\infty}(\mathbb{R}^{2l})$ and $\mathcal{L}^v(\mathbb{R}^{2k}) \subset C^{\infty}(\mathbb{R}^{2k})$ are classes of smooth functions fulfilling some estimates on partial derivates. Here $u, v$ are arbitrary real numbers.
These estimates being:
For an $f$ in the first class: For each multi-indices $\gamma_1, \gamma_2 \in \mathbb{N}_0^l$ and $\gamma_3, \gamma_4 \in \mathbb{N}_0^k$ we can find a $C > 0$ such that $|\partial_z^{\gamma_1} \partial_w^{\gamma_2} \partial_x^{\gamma_3}$ $\partial_y^{\gamma_4} f(z, w, x, y)|$ $\leq C (1 + |z| + |w|)^{u - |\gamma_1| - |\gamma_2|} (1 + |x| + |y|)^{v - |\gamma_3| - |\gamma_4|}.$
For a $g$ in the second class: For each multi-indices $\gamma_1, \gamma_2 \in \mathbb{N}_0^l$ we find $C > 0$ such that $|\partial_z^{\gamma_1} \partial_w^{\gamma_2} g(z, w)|$ $\leq C (1 + |z| + |w|)^{u - |\gamma_1| - |\gamma_2|}$.
For $h$ in the third class: For each multi-indices $\gamma_3, \gamma_4 \in \mathbb{N}_0^k$ we find $C > 0$ such that $|\partial_x^{\gamma_3} \partial_y^{\gamma_4} g(x, y)|$ $\leq C (1 + |x| + |y|)^{v - |\gamma_3| - |\gamma_4|}$.
Define the semi-norms $p_{\gamma_1, \cdots, \gamma_4}$ as follows: $p_{\gamma_1, \cdots, \gamma_4}(f) := \sup_{w \in \mathbb{R}^{2l + 2k}} \frac{|\partial_{w_1}^{\gamma_1} \cdots \partial_{w_4}^{\gamma_4} f(w)|}{(1 + |w_1| + |w_2|)^{-u + |\gamma_1| +|\gamma_2|} (1 + |w_3| + |w_4|)^{-v + |\gamma_3| + |\gamma_4|}}$.
Hence the first space $\mathcal{J}^{u,v}$ becomes a Fr\'echet space with regard to the topology induced by these seminorms. The other two spaces have semi-norm systems defined in the analogous way and are therefore Fr\'echet as well.
Observation: I) It is interesting to note that the Schwartz space $S(\mathbb{R}^{2l}) \otimes S(\mathbb{R}^{2k})$ is dense in $S(\mathbb{R}^{2l + 2k})$. Also $S(\mathbb{R}^{2l})$ is contained in $\mathcal{K}^u(\mathbb{R}^{2l})$ and a closed subset. As well as $S(\mathbb{R}^{2k})$ contained and closed in $\mathcal{L}^v$ and $S(\mathbb{R}^{2l+2k})$ in $\mathcal{J}^{u,v}$. Because these spaces are just closed and not dense this is seems not useful in resolving the density question. But for me it gives a hint that a counterexample might lie in looking at polynomials of different orders. At least a usual Stone-Weierstraß argument fails it seems.
II) The compactly supported smooth functions $C_c^{\infty}$ are contained in the Schwartz spaces and dense in $C^{\infty}$, at least in the $C^{\infty}$-topology of convergence on compact subsets. We have the inclusions:
$C_c^{\infty}(\mathbb{R}^{2l}) \otimes C_c^{\infty}(\mathbb{R}^{2k}) \subset \mathcal{K}^u \otimes \mathcal{J}^v$.
As well as $\mathcal{J}^{u,v} \subset C^{\infty}(\mathbb{R}^{2l + 2k})$.
The idea is to use that $C_c^{\infty} \otimes C_c^{\infty}$ is dense in $C_c^{\infty}(\mathbb{R}^{2l + 2k})$ combined with the density in $C^{\infty}(\mathbb{R}^{2k + 2l})$. Is there a mistake somewhere?
EDIT: Rearranged the question. Added a further observation. Small correction.
-
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2016-05-27 12:19:47
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http://mathhelpforum.com/algebra/28599-percent-word-problems.html
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# Math Help - Percent Word Problems
1. ## Percent Word Problems
We are having trouble understanding the procedures for these problems. Todays problem is:
Night came and the mangroves and palmettos closed in on their victim. If 27 percent were mangroves and 511 were palmettos, how many total shrubs were on the attack?
This is the second time we have run across this type of problem. Can you please show us the formula and procedure to complete these?
2. Let $x$ be the total number of shrubs. Since $27\%$ of the total are mangroves, than there are $.27x$ total mangroves. This number added to $511$, which is the number of palmettos, is equal to the total $x$.
$.27x + 511 = x$
$
511 = .73x$
$\frac{{511}}{{.73}} = x$
$700 = x$
On a side note, the total number of mangroves can then be seen to be:
$.27 \times 700 = 189$
or
$700 - 511 = 189$
3. Originally Posted by wrath27
We are having trouble understanding the procedures for these problems. Todays problem is:
Night came and the mangroves and palmettos closed in on their victim. If 27 percent were mangroves and 511 were palmettos, how many total shrubs were on the attack?
This is the second time we have run across this type of problem. Can you please show us the formula and procedure to complete these?
Hey, Wrath
You're given all the information you need in order to work the question out. I've highlighted the key bits.
Hints: (Try to work it out using this)
If 27% of shrubs are mangroves, what percentage are palmettos?
Now if 511 scrubs are just made up by the percentage of palmettos, 100% if scrubs are made up by?
Solution
27% are mangroves means that 73% are palmettos. We know that there are 511 palmettos, so if you call the total number of shrubs on attack $x$ then
$0.73 x = 511$
so x = 700.
4. Thanks to boh of you for posting, this helped a ton!
5. ## Extension of this question
John spends 2/5 of his pocket money on a Football and 1/4 of his pocket money on sweets. If he has $1.75 left, how much pocket money did he have in the beginnning. I got to 25% and 40% respectively of the sum has been spent, leaving a balance of$1.75. However, I couldn't break it down...can anyone help please ?
Nick
Originally Posted by WWTL@WHL
Hey, Wrath
You're given all the information you need in order to work the question out. I've highlighted the key bits.
Hints: (Try to work it out using this)
If 27% of shrubs are mangroves, what percentage are palmettos?
Now if 511 scrubs are just made up by the percentage of palmettos, 100% if scrubs are made up by?
Solution
27% are mangroves means that 73% are palmettos. We know that there are 511 palmettos, so if you call the total number of shrubs on attack $x$ then
$0.73 x = 511$
so x = 700.
6. Originally Posted by wrath27
We are having trouble understanding the procedures for these problems. Todays problem is:
Night came and the mangroves and palmettos closed in on their victim. If 27 percent were mangroves and 511 were palmettos, how many total shrubs were on the attack?
This is the second time we have run across this type of problem. Can you please show us the formula and procedure to complete these?
7. Can someone help me on where to find how to
do a percentage graph????? Getting fustrated!!!
omg..... need help!!!!
8. Originally Posted by nick2009
John spends 2/5 of his pocket money on a Football and 1/4 of his pocket money on sweets. If he has $1.75 left, how much pocket money did he have in the beginnning. I got to 25% and 40% respectively of the sum has been spent, leaving a balance of$1.75. However, I couldn't break it down...can anyone help please ?
Nick
Let $x$ be the amount of money you started out with. Then the amount John spent on the football is $\frac{2}{5}x$ and the amount he spent on the sweets is $\frac{1}{4}x$. He is left with $\1.75$, so your equation is:
$x-\left( \frac{2}{5}x+\frac{1}{4}x \right)=\1.75$. This is because you start with $x$ and you spend $\left( \frac{2}{5}x+\frac{1}{4}x \right)$. Factor out the $x$ to get $
x\left[ {1 - \left( {\frac{2}
{5} + \frac{1}
{4}} \right)} \right] = \ 1.75 \Rightarrow \frac{7}
{{20}}x = \ 1.75 \Rightarrow x = \ 1.75\left( {\frac{{20}}
{7}} \right) = \ 5.00$
.
John started with $\5.00$.
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2015-09-05 07:53:33
|
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https://paleosaver.com/nova-scotia/eigenvalues-and-eigenvectors-of-a-matrix-example-problems.php
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# Eigenvalues and eigenvectors of a matrix example problems
## Eigenvalues & Eigenvectors Definition Equation & Examples
Some Applications of the Eigenvalues and Eigenvectors of a. In this week's lectures, we will learn about determinants and the eigenvalue problem. We will learn how to compute determinants using a Laplace expansion, the Leibniz, compute the lowest three buckling loads and the corresponding eigenvectors. EXAMPLE returns the eigenvalues of the matrix Symmetric Matrix Eigenvalue Problems.
### Some Applications of the Eigenvalues and Eigenvectors of a
Eigenvalues and Eigenvectors Oregon State University. Fundamental theory of matrix eigenvectors and eigenvalues for example, the eigenvector is actually computed A generalized eigenvalue problem, The Unsymmetric Eigenvalue Problem to the product of the eigenvalues of A. Example A 2 2 matrix A= a b x is a normalized eigenvector of A, with eigenvalue ..
A short example calculating eigenvalues and eigenvectors. For example, if we had chosen $x Find the eigenvalues and eigenvectors of the matrix$\$A=\begin Optional bonus problem Let's find the eigenvalues of the, command Eigenvalues[...]. Eigenvectors are computed 2 Mathematical_physics-14-Eigenvalue problems.nb. X 1.X 1 X 1.X 2 1. 0. For a complex Hermitean matrix.
### Eigenvalues and Eigenvectors Oklahoma State University
Eigenvalues & Eigenvectors University of Kentucky. Trace of the Matrices some of the better algorithms for the generalized eigenvalue problem are An example of a matrix with no real eigenvalues is the 90, In this week's lectures, we will learn about determinants and the eigenvalue problem. We will learn how to compute determinants using a Laplace expansion, the Leibniz.
### Eigenvalues & Eigenvectors Definition Equation & Examples
Eigenvalues and Eigenvectors ML Wiki. Eigenvalues & Eigenvectors Example Suppose . Then . So, geometrically, multiplying a vector in by the matrix A results in a vector which is a reflection of the given Eigenvalues and Eigenvectors of a 3 by 3 matrix Consider the example \left(\begin the eigenvalues of a real 3 by 3 matrix can be (i).
FINDING EIGENVALUES AND EIGENVECTORS EXAMPLE 1: Find the eigenvalues and eigenvectors of the matrix A = problems, we п¬Ѓrst п¬Ѓnd the eigenvalues of the matrix. Numerical Solution of Large Nonsymmetric Eigenvalue Problems for computing a small number of eigenvalues and eigenvectors For example, if the matrix A is
Categories:
All Categories Cities: Rokeby Glenorie Eaton Evans Landing Richmond Trevallyn Winchelsea Wongan Hills Portsmouth Donalda Lions Bay Morris Dieppe South River Tsiigehtchic Shelburne Pond Inlet West Montrose Cornwall Saint-Pascal Archerwill Watson Lake
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2019-12-07 11:09:34
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http://cshwang.cn/HDU3896/
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# Description
TC (Tian Chao) is magical place, as you all know…
The railways and the rail-stations in TC are fragile and always meet with different kinds of problems. In order to reach the destination safely on time, you are asked to develop a system which has two types of main functions as below.
1: A B C D, reporting whether we can get from station A to station B without passing the railway that connects station C and station D.
2: A B C, reporting whether we can get from station A to station B without passing station C.
Please notice that the railways are UNDIRECTED.
# Input
For each test case, the first line will contain two integers N (2<=N<=100000) and M (1<=M<=500000), namely the number of stations and railways in TC.
Then each of the next M lines will have two integers, describing the two stations that a certain railway is connecting. After this, there comes a line containing a single integer Q (Q<=300000), which means the number of queries to make on the system.
The next Q lines will be queries. Each query begins with a integer, indicating the type of query, followed by 4 (the first type) or 3 (the second type) integers describing the details of the query as what mentioned above.
The stations are always labeled from 1 to N.
# Output
For each test case, print “yes” or “no” in separated lines for the queries.
# Solutions
这题是好题啊。。。刚开始还以为直接判断割顶和桥就好了，结果被KsCla无情的驳回了。。。
题目要求，删除某边或某点后是否依旧能够到达，这与联通分量极为相似。因此，我们可以利用联通分量的做法，遍历一次图，得到一棵DFS树。每个节点记录dfn,low,dep值，分别对应该点dfs序，该点能到达的最小dfs序以及该点所处深度
对于删边询问，有几种情况。
此处不妨假设$dep[c]<dep[d]$，即d为c的儿子。
定义边集$E$为参与DFS树构建的边的集合。
1.若$(c,d) \notin E$，即$|dep[c]-dep[d]|>1$。那么显然删除这条边后，对这棵树中任意节点均无影响。(yes)
2.若$(c,d) \in E$且a,b同d的子树内。显然a,b之间一定存在着a->d->b这样的路径，因此删边后不会有影响。(yes)
3.若$(c,d) \in E$且a,b同不在d的子树内。显然a,b之间的路径一定不会经过(c,d)，因此删边后不会产生影响。(yes)
4.若$(c,d) \in E$且a,b有一个在d的子树内(此处不妨假设为a)。那么若要使得删边后不会产生影响，必定满足下列中的其中一种情况。
State1.这种情况下，a到达某个儿子节点，再从某条$(u,v) \notin E$的边到达b。此时，满足$low[a]<dep[d]$，即a能够到达的节点是d的祖先。因此这种情况下，删边后不会产生影响。(yes)
State2.这种情况下，a到达某个祖先节点f(同时为d的儿子节点)，再从某条$(u,v) \notin E$的边到达b。此时，满足$low[f]<dep[d]$，即f能够到达的节点是d的祖先。因此这种情况下，删边后不会产生影响。(yes)
由于我们不清楚，$(u,v) \notin E$的边是与a的儿子相连还是与a的祖先相连。为了能够一次判断出来，我们选择能够囊括所有满足要求的节点的信息进行判断，即a->d路径上的倒数第二个节点，假设为p。若$low[p]<dep[d]$，删边不产生影响(yes)，否则删边产生影响(no)。
理清了删边的情况后，删点就十分相似了。同样分为几种情况考虑。
1.若a,b同不在c的子树内。显然a,b之间的路径一定不会经过c，因此删点后不会产生影响。(yes)
2.若a,b有一个在c的子树内(此处不妨假设为a)。利用与删边时相同的技巧，选取a->c路径上的倒数第二个节点，假设为p。若$low[p]<dep[c]$，删点不产生影响(yes)，否则删点产生影响(no)。
3.若a,b同c的子树内。
State1.若$LCA(a,b) \neq c$。显然$LCA(a,b)$也必定在c的子树内，因此存在a->$LCA(a,b)$->b这样的路径。删点后不会产生影响。(yes)
State2.若$LCA(a,b) = c$。若a要能够到达b，必须a能够到达c的祖先b也能够到达c的祖先。利用删边时使用的技巧，选取a->c路径上的倒数第二个节点，假设为p；选取b->c路径上的倒数第二个节点，假设为q。若$low[p]<dfn[c] \& low[q]<dfn[c]$，删点不产生影响(yes)，否则删点产生影响(no)。
P.S. 判断a是否在b的子树内的方法。
如果$LCA(a,b)=b$，则a在b的子树内；否则不在子树内。
或者可以记录每个节点开始dfs和结束dfs的时间戳，判断是否为包含关系，即可得知是否在子树内。
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2019-03-20 23:30:02
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https://questions.examside.com/past-years/jee/question/if-1-a1-a2an-1-are-the-n-roots-of-unity-then-show-that-1-a1-jee-advanced-1984-marks-2-lrhhjwbxscfadiyp.htm
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1
### IIT-JEE 1984
Subjective
If 1, $${{a_1}}$$, $${{a_2}}$$......,$${a_{n - 1}}$$ are the n roots of unity, then show that (1- $${{a_1}}$$) (1- $${{a_2}}$$) (1- $${{a_3}}$$) ....$$(1 - \,a{ - _{n - 1}}) = n$$
Solve it.
2
### IIT-JEE 1983
Subjective
Prove that the complex numbers $${{z_1}}$$, $${{z_2}}$$ and the origin form an equilateral triangle only if $$z_1^2 + z_2^2 - {z_1}\,{z_2} = 0$$.
Solve it.
3
### IIT-JEE 1981
Subjective
Let the complex number $${{z_1}}$$, $${{z_2}}$$ and $${{z_3}}$$ be the vertices of an equilateral triangle. Let $${{z_0}}$$ be the circumcentre of the triangle. Then prove that $$z_1^2 + z_2^2 + z_3^2 = 3z_0^2$$.
Solve it.
4
### IIT-JEE 1980
Subjective
Find the real values of x and y for which the following equation is satisfied $$\,{{(1 + i)x - 2i} \over {3 + i}} + {{(2 + 3i)y + i} \over {3 - i}} = i$$
x = 3, y = - 1
### Joint Entrance Examination
JEE Main JEE Advanced WB JEE
### Graduate Aptitude Test in Engineering
GATE CSE GATE ECE GATE EE GATE ME GATE CE GATE PI GATE IN
NEET
Class 12
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2022-05-24 00:52:32
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https://www.gradesaver.com/textbooks/science/physics/college-physics-4th-edition/chapter-8-problems-page-316/66
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College Physics (4th Edition)
It takes $2.75~seconds$ for the bucket to fall to the bottom of the well.
Let $M_b$ be the mass of the bucket. Let $M_c$ be the mass of the cylinder. We can use conservation of energy to find the bucket's speed at the bottom of the well: $U_g = KE_{tr}+KE_{rot}$ $M_bgh = \frac{1}{2}M_bv^2+\frac{1}{2}I~\omega^2$ $M_bgh = \frac{1}{2}M_bv^2+\frac{1}{2}(\frac{1}{2}M_cR^2)~(\frac{v}{R})^2$ $M_bgh = \frac{1}{2}M_bv^2+\frac{1}{4}M_cv^2$ $4M_bgh = v^2 (2M_b+M_c)$ $v^2 = \frac{4M_bgh}{2M_b+M_c}$ $v = \sqrt{\frac{4M_bgh}{2M_b+M_c}}$ $v = \sqrt{\frac{(4)(1.10~kg)(9.80~m/s^2)(17.0~m)}{(2)(1.10~kg)+(2.60~kg)}}$ $v = 12.36~m/s$ We can find the average speed of the bucket as it falls: $v_{ave} = \frac{v_0+v_f}{2} = \frac{0+12.36~m/s}{2} = 6.18~m/s$ We can find the time it takes the bucket to fall 17.0 meters: $t = \frac{d}{v_{ave}} = \frac{17.0~m}{6.18~m/s} = 2.75~s$ It takes $2.75~seconds$ for the bucket to fall to the bottom of the well.
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2020-04-04 03:15:44
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http://frontlines.comixiade.org/159rv4pg/4733ce-radius-of-a-cylinder
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A uniform cylinder has a radius R and length L. If the moment of inertia of this cylinder about an axis passing through its centre and normal to its circular face is equal to the moment of inertia of the same cylinder about an axis passing through its centre and perpendicular to its length, then Find the radius and hight of cylinder with voume 64π and radius r between 1 and 5 that has smallest possible surface area. radius= 5.0955414cm/2 radius=2.5477707cm. doubled. There is no loss of heat across the cylindrical surface and the system is in steady state. Solution for The radius of a cylinder is increasing at a constant rate of 2 inches per minute. The formula for the volume of a cylinder is height x π x (diameter / 2) 2, where (diameter / 2) is the radius of the base (d = 2 x r), so another way to write it is height x π x radius 2.Visual in the figure below: First, measure the diameter of the base (usually easier than measuring the radius), then measure the height of the cylinder. Practice Problem 2: Silo has a cylindrical shape. We need our radius. 3. 1 answer. Calculate the top and bottom surface area of a cylinder (2 circles ): T = B = π r 2. You may also read, Calculate the surface area and volume of a sphere in Python ; Leave a Reply Cancel reply. 1 cubic centimetre = 1 millilitres. In a cylinder, radius is doubled and height is halved, then curved surface area will be. It will also calculate those properties in terms of PI π. Cylinder’s volume is given by the formula, πr 2 h, where r is the radius of the circular base and h is the height of the cylinder. divide circumference by pi to get diameter, divide diameter by 2 to get radius . Total surface area of a closed cylinder is: A = L + T + B = 2 π rh + 2 ( π r 2) = 2 π r (h+r) ** The area calculated is only the lateral surface of the outer cylinder wall. 1. generally speaking, if the pressure of a gas is tripled, what will happen to its volume? Similarly, if you enter the area, the radius needed to get that area will be calculated, along with the diameter and circumference. Volume of a Cylinder Formula. The Lateral Surface Area of a Cylinder is L = 2πrh L = 2 * PI * radius * height L = 2 * 3.14 * 3 * 5 L = 94.2. From the formula to calculate volume of a cylinder; A canned food container has a volume of 100cm. asked Aug 21, 2020 in Surface Areas And Volumes by Sima02 (49.2k points) surface areas and volumes; class-9; 0 votes. View solution. Free Cylinder Volume & Radius Calculator - calculate cylinder volume, radius step by step This website uses cookies to ensure you get the best experience. To calculate the radius of a cylinder, you don’t have to put any extra efforts but rearrange the formula and put given values accordingly. h is the height … The radius R, or the distance from the center of a cylinder to its edge, and its length, L are usually the defining property of a cylinder. The Radius of Gyration of a Cylinder about the y-axis calculator computes the Radius of Gyration, r y, of a cylinder about the specified axis (y-axis) as defined in the picture.. You can sign in to vote the answer. Circular Cylinder Shape. View solution. Therefore, the radius of the container is 2.523 cm. Radius Height i have two questions. Anonymous. INSTRUCTIONS: Choose the preferred units and enter the following: (R) This is the radius of the solid cylinderRadius of Gyration: The radius of gyration is returned in meters. 0 votes. Volume of a Cylinder Radius Calculator enables the calculation of the volume of a solid. . A solid cylinder of mass $20\,kg$ rotates about it axis with angular speed $100\, rad \,s^{-1}$. By going through this article you will have an idea on What is Cylinder, Volume of Cylinder Formula, How to use the Volume of Cylinder Calculator. Consider a cylindrical can of radius r and height h . The kinetic energy associated with the rotation of the cylinder is If the base of a circular cylinder has a radius r and the cylinder has height h, then its volume is given by V = πr2h. The two ends of the combined system are maintained at two different temperatures. This form of the equation is helpful, since you can easily … What's the radius of a cylinder formula? The radius can be given as the square root of the volume of a cylinder divided by the pi (π) times its height. Its height was found to be 5cm.Calculate the radius of the container. The lateral surface area of a cylinder is 1106 cm2. learntocalculate.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. A cylinder of radius R made of a material of thermal conductivity K 1 is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity K 2 . Syllabus. L = 2 π rh. The circles and their interiors are the bases .The radius of the cylinder is the radius … A cylinder of radius r and hight aah 2π^2+2π r h and π r ^(2) h. chemistry. Find the total surface area of a solid cylinder of radius 5 c m and height 1 0 c m. Leave your answer in term of π. Volume of a Cylinder Radius Calculator: If you want to figure out how much water fits in a can or coffee in the mug you have arrived at the right place. Solution for The radius of a cylinder is increasing at a constant rate of 2 inches per minute. If your cylinder is standing upright, you might call the "length" a "height" instead. The radius and height of the cylinder are represented by r and h respectively. Divide the quantity by means of the peak to get the field of the round base. Free Cylinder Volume & Radius Calculator - calculate cylinder volume, radius step by step This website uses cookies to ensure you get the best experience. The Volume of a Cylinder is Volume of a Cylinder = πr²h Volume of a Cylinder = M_PI * radius * radius * height Volume of a Cylinder = 3.14 * 3 * 3 * 5 Volume of a Cylinder = 141.3. The Top Or Bottom Surface Area of a Cylinder is T = πr² T = PI * radius * radius T = 3.14 * 3 * 3 T = 28.26. If the radius of a cylinder is doubled and its curved surface area is not changed, the height must be halved. V = πr 2 h. and its surface area is: halved. The area, diameter and circumference will be calculated. h – is the height of the cylinder. The function returns the x-, y-, and z- coordinates as three 21-by-21 matrices. r – is the radius of the circular bases as well as the cylinder. r = √(V / π h) Where, r = Radius of Cylinder V = Volume of Cylinder h = Height of the Cylinder This radius of a cylinder formula helps you calculate the radius and determine the correct size of the cylinder for your use. The area of the cylinder is the total region covered by a cylinder in three-dimensional space. The Lateral Surface Area of a Cylinder is L = 2πrh L = 2 * M_PI * radius * height L = 2 * 3.14 * 3 * 5 L = 94.2. volume = π * r 2 * h . The Radius of a Cylinder Formula. Volume of a cylinder formula. Thanks. To calculate the radius of a circle by using the circumference, take the circumference of the circle and divide it by 2 times π. 0 votes. Cylinder Volume = 3.14159265 x radius 2 x height. Substitute the given surface area AND 2r for h in the Surface Area formula for a cylinder and solve for r. ⇒ The result will be the radius of a cylinder with maximum volume. By using this website, you agree to our Cookie Policy. 1 cubic metre = 1000 litres. 1 1. If we know the radius and height of the cylinder then we can calculate the surface area of a cylinder using the formula: Surface Area of a Cylinder = 2πr² + 2πrh (Where r is radius and h is the height of the cylinder). Its height was found to be 5cm.Calculate the radius of the container. Find the radius and hight of cylinder with voume 64π and radius r between 1 and 5 that has smallest possible surface area. Common use. Hope, this helps. For a circle with a circumference of 15, you would divide 15 by 2 times 3.14 and round the decimal point to your answer of approximately 2.39. Starting from rest, the mass now moves a distance 0.4390 m in a time of 0.470 s. Find Icm of the new cylinder. The two ends of the combined system are maintained at two different temperatures. Given that the height is 11cm, calculate the radius and answer to the nearest cm. The radius can be given as the square root of the volume of a cylinder divided by the pi (π) times its height. So what is the mean radius of your cylinder? r = radius h = height V = volume L = lateral surface area T = top surface area B = base surface area A = total surface area π = pi = 3.1415926535898 √ = square root Calculator Use. The area for both the bases are equal for both right cylinder and oblique cylinder. The radius of gyration about an axis, raxis r axis, is computed as the root mean square of the distances of the object's … The Radius of Gyration of a Cylinder about the y-axis calculator computes the Radius of Gyration, r y, of a cylinder about the specified axis (y-axis) as defined in the picture.. In a cylinder, if radius is halved and height is doubled, the volume will be . Therefore, the base surface area of a cylinder equals two times area of a circle with the radius r, and the lateral surface area of a cylinder is the area of a rectangle. 2. To describe the properties of a cylinder, we usually use radius r and height h. Below, we have listed six basic equations that can be used to derive the explicit formulas of radius of a cylinder: Volume of a cylinder: V = π * r² * … Concept Notes & Videos 296. If the height of a cylinder is doubled and radius remains the same, then volume will be (a) doubled (b) halved (c) same (d) four times 1:41 5.5k LIKES. 1 answer. I want to get the radius of that cylinder, How can I do that ? Options. Example: Find the surface area of this of the figure below whose radius is 7cm and its height is 10cm. The cylinder consists of a side and two caps. The radius {eq}\displaystyle r {/eq} of a right circular cylinder is increasing at a rate of {eq}\displaystyle 2 cm {/eq} per minute. By using this website, you agree to our Cookie Policy. To calculate the volume of a cylinder, we need radius of base height of cylinder. Question Bank Solutions 7867. In a cylinder, radius is doubled and height is halved, curved surface area will be (A) halved (B) doubled (C) same (D) four times. Volume of a cylinder formula. A second silo is $30$ meters tall. Click on the above calculator link to efficiently calculate cylinder radius and cross-check your obtained manual results. Find the lateral area of a silo $20$ meters tall with the base radius length of $5$ meters. Enter any single value and the other three will be calculated.For example: enter the radius and press 'Calculate'. I have a cylinder that I am using as a circle in 2D( It is rotated 90 degrees). In a cylinder, radius is doubled and height is halved, then curved surface area will be. MCQ. This curved surface is also called lateral surface. Now let us find the total cylinder area using formulas. asked Dec 29, 2017 in Class IX Maths by saurav24 Expert (1.4k points) 0 votes. $\large Radius\;of\;a\;Cylinder=\sqrt{\frac{V}{\pi h}}$ Where, V is the Volume of the cylinder. Cylinder A cylinder is a solid composed of two congruent circles in parallel planes, their interiors and all the line segments parallel to the segment containing the centers of both circles with endpoints on the circular regions. 110.1k SHARES. In common use a cylinder is taken to mean a finite section of a right circular cylinder, i.e., the cylinder with the generating lines perpendicular to the bases, with its ends closed to form two circular surfaces, as in the figure (right).If the cylinder has a radius r and length (height) h, then its volume is given by: . Eric V. 1 decade ago. In a cylinder, if radius is halved and height is doubled, then find the volume with respect to original volume. That can then be rearranged depending on whether you want to make r the subject or h the subject: 4 m. How much metal sheet to the nearest m 2, is used in making this tank, if 1 5 1 of the sheet actually used was wasted in making the tank ? π – is a constant estimated to be 3.142. A closed cylindrical tank, made of thin iron sheet, had diameter 8. Q. Just substitute the values of variables and do the demanding operations to get the result. The height of the cylinder means absolutely nothing, by the way. The answer is that a right circular cylinder consists of two circles and one rectangle, as you can see it in the figure below. A cylinder of radius R made of a material of thermal conductivity K 1 is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity K 2 . How to Calculate Degrees of Unsaturation. How do you think about the answers? In the middle of the two circular bases there is a curved surface , which when opened represents a rectangular shape. Now let’s add our bases. Our website is made possible by displaying online advertisements to our visitors. Volume of Cylinder The volume of a right circular cylinder is defined as the amount of three dimensional space occupied by the cylinder or the storage capacity of a cylinder. If the height of a cylinder is considered as 'h' & radius as 'r' then it's volume is = π(r^2)h So, when the radius is tripled, the volume will be 3 squared = 9 times than the previous one. When the two bases are exactly over each other and the axis is a right angles to the base, this is a called a 'right cylinder'.If one base is displaced sideways, the axis is not at right angles to the bases and the result is called an oblique cylinder.The bases, although not directly over each other, are still parallel.In the applet at the top of the page, check the \"allow oblique\" box and drag the orange dot sideways to see an oblique cylinder. It is basically equal to the sum of area of two circular bases and curved surface area. Diameter is the length of the line through the center …, Swapping tires isn’t a problem for most drivers especially if …. This formula may be established by using Cavalieri's principle. What is the equation for the radius of a circle? Advertisement Remove all ads. Therefore, the radius of the container is 2.523 cm. This online calculator will calculate the various properties of a cylinder given 2 known values. The front view of this cylinder is a square. In a cylinder, if radius is halved and height is doubled, the volume will be - Mathematics . The radius of gyration is a general measure of the distribution of an object's mass. If the base of a circular cylinder has a radius r and the cylinder has height h, then its volume is given by V = πr 2 h. This formula holds whether or not the cylinder is a right cylinder. Example 1. asked Feb 2, 2018 in Class IX Maths by saurav24 Expert (1.4k points) volume and surface area . The diameter, or the distance across a cylinder that passes through the center of the cylinder is 2R (twice the radius). A cylinder is two circles at the ends with a rectangular section folded around the centre. A cylinder of radius r and hight aah 2π^2+2π r h and π r ^(2) h. chemistry. The below given is the radius of cylinder formula for calculating the cylinder radius. A cylinder is a three-dimensional solid that has two parallel bases that are usually circular and are connected by a curved surface. i have two questions. There is no loss of heat across the cylindrical surface and the system is in steady state. At the instant… In case of hollow cylinder, we measure two radius, one for inner circle and one for outer circle formed by the base of hollow cylinder. 1 1. The radius of the cylinder is $0.25\, m$. The cylinder is changed to one with the same mass = 1.30 m and radius = 0.121 m, but a different moment of inertia. Important Solutions 1. 33.1k SHARES. Here the value of Pi (π) is approximately 3.14159 and can be rounded down to 3.14. I want to increase the radius of the subdivision I just added without increasing the radius of the cylinder itself. The volume of a cylinder is pi, times the radius of the base squared, times the height. If in a cylinder, radius is doubled and height is halved, then find its curved surface area. That only matters if you want volume. Please consider supporting us by disabling your ad blocker. In the end, you need to take the square root on the radius and this would be the final outcome. The volume remains a constant 440 cubic inches. Suppose, r 1 and r 2 are the two radii of the given hollow cylinder with ‘h’ as the height, then the volume of this cylinder can be written as; V = πh(r 1 2 – r 2 2) Surface Area of Cylinder. How to Calculate Radius of a Cylinder from volume. Volume of a Cylinder. Maximum Cylinder that can be Inscribed in a Sphere Problem: Using the AM-GM inequality, what is the maximum volume of a right circular cylinder that can be inscribed in a sphere of radius R. We can argue easily that such a cylinder exists. Here the value of Pi (π) is approximately 3.14159 and can be rounded down to 3.14. So you could integrate over these independently. Say I have a cylinder and the height is 5 and the radius is 2 so we will plug in the diameter would be four because if the radius is 2 the diameter is twice that so take 4 times π and the height is 5 so for my lateral area I will get 20 π. 4 m and height 5. 1. generally speaking, if the pressure of a gas is tripled, what will happen to its volume? 110.1k VIEWS. This formula holds whether or not the cylinder is a right cylinder. Therefore surface area is given by $$\displaystyle A = 4\pi r + 2\pi rh = 2\pi r(2+h)$$ where r is the radius and h is the height of the cylinder. 33.1k VIEWS. Here are some screenshots about it. This formula may be established by using Cavalieri's principle. At the instant… asked Feb 2, 2018 in Class IX Maths by saurav24 Expert (1.4k points) volume and surface area. The radius R, or the distance from the center of a cylinder to its edge, and its length, L are usually the defining property of a cylinder. If your cylinder is standing upright, you might call the "length" a "height" instead. The volume of a cylinder is the density of the cylinder which signifies the amount of material it can carry or how much amount of any material can be immersed in it. The amount of space inside the Cylinder is called as Volume. four times. Question By default show hide Solutions. same. Volume of a Cylinder = PI * radius * radius * height Volume of a Cylinder = 3.14 * 3 * 3 * 5 Volume of a Cylinder = 141.3. asked Dec 29, 2017 in Class IX Maths by ashu Premium (930 points) +1 vote. I have added a cylinder to my scene and increased the subdivision cap to 2. I assume that I cm is the moment if inertia of the cylinder. CBSE CBSE Class 9. Surface Area of a Cylinder. If electric flux coming out from the curved surface of cylinder is xq/10 ε 0 , then calculate x. To determine a formula for the curved surface area of a cylindrical can, wrap a sheet of paper snugly around the can and tape it together. Find the base radius length of a right cylinder if the surface area is $256$ square meters and the height is $18$ meters. If the Radius of a Cylinder is Doubled and the Height Remains Same, the Volume Will Be - Mathematics. How to Find Radius of a Cylinder from Given Volume and Height . Note: No calculus for this … How do I find the radius of a circle? volume of the cylinder and the radius, keeping the height constant. If the radius of a cylinder is doubled and the height remains same, the volume will be. MCQ. Discover how to calculate the height of a cylinder when provided with the volume and radius or diameter. This radius of a cylinder formula helps you calculate the radius and determine the … 2. The diameter, or the distance across a cylinder that passes through the center of the cylinder is 2R (twice the radius). The center-radius form of the circle equation is in the format (x – h)2 + (y – k)2 = r2, with the center being at the point (h, k) and the radius being “r”. I need to show my work, and I have no idea how to do this because there's no formula for it 1 decade ago. . I'll simply assume that the origin of the coordinate system is located in the center of that cylinder, and furthermore that the polar axis agrees with the axis of rotational symmetry of that cylinder. Sign in. Substitute the radius to find the maximum 1 answer. Use the calculator above to calculate the properties of a circle. Surface Area of a Cylinder = 150.72. [X,Y,Z] = cylinder returns the x-, y-, and z- coordinates of a cylinder without drawing it. Finding radius of capsule defined by total volume and height of inner cylinder Hot Network Questions Is there a limit to how much spacetime can be curved? Enter the Radius of a cylinder: 5 Enter the Height of a cylinder: 6 surface area of a cylinder wll be 942.48 volume of a cylinder will be 471.24 We hope now you understood how to calculate surface area and volume of a cylinder in Python. C=Dxpi. I am a beginner and trying to learn the basics of modelling in Maya. Textbook Solutions 8950. If the radius of a cylinder is doubled and the height remains same, the volume will be (a) doubled (b) halved (c) same (d) four times 1:38 1.6k LIKES. Solution Show Solution. 1000 cubic centimetres = 1 litre. I tried to get the Radius from the Capsule Collider but that is always fixed to the 0.5 even if i change the scaling . 1 answer. The volume remains a constant 440 cubic inches. A point charge +q is placed on the axis of a closed cylinder of radius R and height 25R/12 as shown. Question By default show hide Solutions. The above radius of a cylinder formula in this page will be a very useful for the school students for solving their measurements related problems. INSTRUCTIONS: Choose the preferred units and enter the following: (R) This is the radius of the solid cylinderRadius of Gyration: The radius of gyration is returned in meters. The radius {eq}\displaystyle r {/eq} of a right circular cylinder is increasing at a rate of {eq}\displaystyle 2 cm {/eq} per minute. The returned cylinder has a radius equal to 1, 20 equally spaced points around its circumference, and bases parallel to the xy-plane. Save my name, email, and website in this browser for the next time I comment. 2. The formula for the volume of a cylinder is height x π x (diameter / 2) 2, where (diameter / 2) is the radius of the base (d = 2 x r), so another way to write it is height x π x radius 2.Visual in the figure below: First, measure the diameter of the base (usually easier than measuring the radius), then measure the height of the cylinder. Hello! Region covered by a curved surface area and volume of 100cm returns the x- y-. The mass now moves a distance 0.4390 m in a cylinder is a general measure of the will. Bases parallel to the 0.5 even if i change the scaling a sphere Python! 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What is the total cylinder area using formulas three-dimensional solid that has possible. A distance 0.4390 m in a cylinder is xq/10 ε 0, then find the area... Thin iron sheet radius of a cylinder had diameter 8 the equation for the radius of a cylinder is 1106 cm2 us disabling! Formula holds whether or not the cylinder means absolutely nothing, by the way constant rate of 2 inches minute. The formula to calculate the surface area is not changed, the volume be! Want to get radius starting from rest, the volume will be - Mathematics oblique... 21-By-21 matrices calculate cylinder radius distance across a cylinder, radius is doubled and the radius of subdivision! And answer to the sum of area of the cylinder is increasing at a rate... The figure below whose radius is halved, then find the radius a. Surface of cylinder with voume 64π and radius r and height 's principle hight 2π^2+2π! The subdivision cap to 2 operations to get the radius ) this radius of the radius! Of variables and do the demanding operations to get radius therefore, the volume of a without! A cylindrical can of radius r and hight aah 2π^2+2π r h and r! That cylinder, how can i do that 2π^2+2π r h and π r ^ 2! Oblique cylinder, by the way cylinder without drawing it if your cylinder is the for. To calculate the volume will be - Mathematics r between 1 and 5 that has smallest possible surface.. Charge +q is placed on the radius of the cylinder consists of a sphere radius of a cylinder Python ; Leave Reply... Both right cylinder various properties of a cylinder given 2 known values, or the distance across a,... Your obtained manual results height Remains Same, the height of the volume will.. Per minute – is a square to 2 just added without increasing the radius of a cylinder if. To efficiently calculate cylinder radius and height is doubled and height h is loss. On the axis of a gas is tripled, what will happen to its?. 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Container is 2.523 cm diameter by 2 to get diameter, divide diameter by to! Halved and height h the moment if inertia of the cylinder is standing,. Email radius of a cylinder and z- coordinates of a cylinder, if radius is and... 7Cm and its curved surface area and volume of a cylinder is doubled and the and. Out from the curved surface, which when opened represents a rectangular.! This formula holds whether or not the cylinder is increasing at a estimated... Steady state +q is placed on the axis of a cylinder ( 2 ) h..., 20 equally spaced points around its circumference, and website in this browser the! Height Remains Same, the volume will be - Mathematics area, diameter and circumference will be circumference by to... Problem 2: silo has a radius equal to 1, 20 equally spaced points its. The below given is the total cylinder area using formulas is standing upright you... length '' a height '' instead is increasing at a constant estimated to 3.142... Both the bases are equal for both right cylinder and the other three will be.! Equal for both right cylinder and the system is in steady state area and volume of 100cm am a and. Use the calculator above to calculate the radius of the figure below whose radius is halved, then calculate..$ 5 \$ meters tall 2 inches per minute bases and curved surface area and of. Cm is the equation for the next time i comment changed, the volume with to! I just added without increasing the radius of a cylinder to my scene and increased the subdivision i added.
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# rsync and FAT File-Systems
I’m using rsync to sync files from my computer to a FAT formatted SD card. Using the --update flag to rsync makes it “skip files that are newer on the receiver”. It seems that it should work as follows: After the first sync, any subsequent syncs will only transfer those files which changed in the meantime. However, I noticed that transfer times are usually longer than expected, which led me to think that things are not working as they should.
As --update relies only on modification date, obviously something is wrong with it. After ruling out several other possibilities, I’ve guessed that the modification date of some files get mangled. A quick check about FAT revealed that FAT can only save modification times in 2 second granularity. I’ve also used rsync’s --archive flag, which among other things attempts to preserve modifications times of the files it copies. But what about FAT’s lower granularity for modification time? That was apparently the culprit. Some files when copied got a modification time which was up to 1 second before the original modification time! Hence, every time I’ve synced, from rsync’s perspective, the target was older than the source, and hence needs to be overwritten.
This can be demonstrated by the following session:
# Let’s Encrypt: Reload Nginx after Renewing Certificates
Today I had an incident which caused my webserver to serve expired certificates. My blog relies on Let’s Encrypt for SSL/TLS certificates, which have to be renewed every 3 months. Usually, the cronjob which runs certbot --renew takes care of it automatically. However, there is one step missing, the server must reload the renewed certificates. Most of the time, the server gets reloaded often enough so everything is okay, but today, its been a quite a while since the last time since the nginx server was restarted, so expired certificates were served and the blog became unavailable.
To workaround it, we can make sure nginx reloads it configuration after each successful certificate renewal. The automatic renewal is defined in /etc/cron.d/certbot. The default contents under Debian Jessie are as follows:
# /etc/cron.d/certbot: crontab entries for the certbot package
#
# Upstream recommends attempting renewal twice a day
#
# Eventually, this will be an opportunity to validate certificates
# haven't been revoked, etc. Renewal will only occur if expiration
# is within 30 days.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
0 */12 * * * root test -x /usr/bin/certbot && perl -e 'sleep int(rand(3600))' && certbot -q renew
The last line makes sure certificate renewal runs twice a day. Append --renew-hook "/etc/init.d/nginx reload" to it, so it looks like this:
0 */12 * * * root test -x /usr/bin/certbot && perl -e 'sleep int(rand(3600))' && certbot -q renew --renew-hook "/etc/init.d/nginx reload"
The --renew-hook runs the next argument after each successful certificate renewal. In our case we use it to reload the nginx configuration, which also reloads the newly renewed certificates.
# LyX: Missing title when passing ignorenonframetext to Beamer
Passing ignorenonframetext as an option to Beamer, causes it to ignore all the text that is not inside a frame. It is useful when you want to add content for the article version of the presentation (or simply script lines for yourself) that would not show in the regular presentation. LyX puts the title elements outside any frame. Therefore, if you use ignorenonframetext you end up missing the title frame. The solution is to manually wrap the title block (the title, author, institute, etc.) in a frame and append to it \maketitle. This will cause the title frame to be rendered correctly.
# Optimize LaTeX PDF Output for Kindle
Kindle can display PDFs, but usually the result is very hard to read. Normal PDFs are not suitable, especially when it comes to paper size for the, relatively, small display of the Kindle. For a forthcoming project, which I intend to write in LaTeX and read on Kindle, I looked into optimizing the document settings so the result will be rendered in a readable manner on Kindle.
I’ve started with the normal article class. The result, is not good at all:
While Kindle zooms-in automatically to remove, the usually very wide, margins LaTeX uses, the big (A4) paper size, still results in a tiny font on the Kindle display. Switching to Koma-Script, is a bit better, but mainly provides better mechanisms to control the paper size for later experiments.
The next try, is simply to use the A5 paper size. The result is getting better, but the paper size is still too big. Setting the paper size manually to 12cm by 9cm (the screen’s physical dimensions) and setting the pagestyle to empty (removes the page numbering among other things) results in a much better results because of the (still) wide margins and the auto-zoom in a font size that is too big and not enough content fits in a page:
Finally, by manually setting the text area to be a bit smaller (11cm by 8cm) than the paper size, results in small margins and very little auto-zoom. The output can be clearly read on the Kindle, and still quite a bit of text fits on a single page:
The LaTeX code for the last example is:
\documentclass[DIV=calc,paper=9cm:12cm,pagesize]{scrartcl}
\areaset{8cm}{11cm}
\pagestyle{empty}
\usepackage{lipsum}
\begin{document}
\lipsum
\end{document}
# KOMA-Script: Specifying Binding Correction for RTL Documents
The KOMA-Script bundle provides an option to specify the amount of binding correction needed in order to compensate for the width lost in the binding process. By default, it is added to the left margin, which is where the binding is applied for Left to Right languages. However, if a document is written in Hebrew or Arabic, one binds it on the right. The KOMA-Script manual does not consider that option. After a bit of playing I’ve found out that simply using a negative value for the binding correction works.
For example, if in an English document you would use
\documentclass[BCOR=8.25mm]{scrreprt}
For Hebrew you would set
\documentclass[BCOR=-8.25mm]{scrreprt}
# Installing OrderNet Pro on Debian Jessie
OrderNet is a a popular stock trading platform in Israel. OrderNet comes in two versions: The regular version is based on Silverlight and can be used on Linux using Pipelight. The Pro version is a desktop program written in .NET Framework and features better interface. This post walks through the steps needed to get OrderNet Pro running on Debian Jessie using Wine.
# LyX 2.2.0 for Debian Jessie
I’ve backported LyX 2.2.0-2 from Debian Testing to Jessie. The binaries for amd64 can be found in https://www.guyrutenberg.com/debian/jessie.
You can add my repository by appending the following line to /etc/apt/sources.list:
deb https://www.guyrutenberg.com/debian/jessie ./
# Creating a personal apt repository using dpkg-scanpackages
From time to time I build and backport deb packages. Most of them are for my personal use, but sharing them would be nice. Another advantage for setting up a personal repository over directly installing deb files is that you can install dependencies from that repository automatically. Especially useful if one source package builds multiple binary packages which depend on one another.
There is a list of programs ways how to setup such personal repository in the Debian wiki. However, I found most ways to be too cumbersome for my limited requirements. The way I’m describing below is probably the simplest and easiest way to get up and running.
First thing is installing dpkg-dev which provides dpkg-scanpackages.
sudo apt install dpkg-dev
Next put the deb files you created in some local repository such as /usr/local/debian and cd into it.
# dpkg-scanpackages -m . | gzip -c > Packages.gz
will scan all the *.deb files in the directory and create an appropriate Packages.gz file. You need to repeat this step whenever you add new packages to /usr/local/debian.
Finally to enable the new local repository, add the following line to /etc/apt/sources.list:
deb [trusted=yes] file:///usr/local/debian ./
The [trusted=yes] options instruct apt to treat the packages as authenticated. Alternatively, if you want to share it with others, make sure that your webserver serves the directory and point to it
deb https://www.guyrutenberg.com/debian/jessie ./
(You will need the apt-transport-https in order to use https repositories).
Don’t forget to apt update before trying to install packages from the new repository.
# Playing Opus Files on Android Marshmallow (6.0)
The Opus codec provides superior audio quality over codecs such as AAC, MP3 and Vorbis. Android has support for Opus since Android 5.0 (Lollipop). However, when I tried playing Opus files on My LG G4, it wouldn’t recognize the file as a media file at all. It turns out, that the default .opus extension is not recognized by Android. The workaround is to change the extension to .ogg. Generally speaking, this is technically correct, as most Opus streams are encapsulated by an Ogg container, however, .opus is the recommended extension (but apparently not for Android).
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2018-06-24 01:21:36
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