User talk:PAR

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[edit] Gibbs Paradox

I noticed that you edited the article on Gibbs Paradox, and seem to have some comfort level with the material. I have reason to be suspicious of the information theory treatment, but am not technically competent to review it. If you are, would you please take the time to review that section carefully?Kww (talk) 21:46, 21 November 2007 (UTC)

Yes, I plan to do that. This information was added by Shu-Kun Lin, who has apparently published articles on this subject in various respectable journals, so it cannot be rejected without serious consideration. PAR (talk) 22:02, 21 November 2007 (UTC)

[edit] RE: Multiple wikify requests

Hi,

Thanks for the message..

Right now... I am prepareing for an exam on "Material Science"..

While going through these articles, I encountered situations where I couldn't proceed to next page due to lack of Wiki links (internal links).. I corrected some of them.. but right now I do not have enough time to correct all of them so just put wikify requests.. :)

Will either put links, or explanation in talk page after my exams.. :)

The articles I put wikify requests inclue (as u mentioned in your message) :

Slip (materials science)‎ Non-Newtonian fluid‎ Strain (materials science)‎ Creep (deformation) Tensile stress‎ Frank-Read Source‎ Annihilation‎ Burgers vector Interstitial defect‎

Thenks.. DhananSekhar 18:45, 30 November 2007 (UTC)

[edit] re: Pulley

Good morning, PAR. I just had to revert your latest edit to the Pulley article. I understand your point but when you made the change, you brought the vandalism back. If you're going to fix the article, please fix it completely. It is more important that we keep the vandalism out than that we make a technical correction about "unit weight". Thanks. Rossami (talk) 16:22, 10 December 2007 (UTC)

Well, to be factual, we are both screwing this up, and I apologize for my part in it, by not checking for vandalism before making my edit. The use of "unit weight" though, is simply wrong, and you didn't correct that when you tried to edit back in what I had done. Can we proceed slowly from here? I know its a pain to go through a bunch of good edits, looking for the vandalism, but I will try. I reverted to my version, but fixed the "flute and tackle" and "flute and picolo" vandalism. Now, rather than revert because it might still contain vandalism, can you just search for any further vandalism and correct it? Again, sorry about my contribution to this problem. PAR (talk) 16:54, 10 December 2007 (UTC)
In a perfect world, that's the way it should go. In this case, the vandalism went undetected for enough time and your edits hit so many parts of the article simultaneously that it was very difficult to find and fix them all. Again, I will argue that it is far more important that we fix vandalism than to correct technical issues of wording. Even with the mistake, the basic concepts of the page were understandable. Vandalism, on the other hand, discredits the project. I usually can merge the good edits but in this specific case, it really seemed safer for our readers to over-revert and ask you to recreate your edits.
Anyway, the vandals still messed with the figure numbering. I'll go fix that. And something about your edits is adding non-breaking spaces that have to be cleaned up. If you could look into why those are showing up, that would be helpful. Thanks. Rossami (talk)
It looks good. The non-breaking spaces are there on purpose, they prevent italicized letters from running into the next letters. This W does not have a non-breaking space, this W  does. PAR (talk) 19:53, 10 December 2007 (UTC)
The first example looks right. The second forces an odd double-space after the W and looks like a misprint. In neither case did not italicized letters run into the subsequent letters. Rossami (talk) 03:07, 11 December 2007 (UTC)

[edit] Images of two-dimensional coordinate systems?

Hi PAR,

Have we met before? I'm thinking that we have, but, unfortunately, I can't remember where — maybe at the equipartition theorem? :)

I noticed your wonderful red-and-cyan pictures at the articles for prolate and oblate spheroidal coordinates! I really like the way you labeled the individual isosurfaces, too. Would you be willing to do something similar for the other two- and three-dimensional orthogonal coordinate systems, or at least tell me how to do it? I've long been thinking of fixing them up and would really appreciate your help. :) Willow (talk) 23:45, 17 January 2008 (UTC)

Hi - yes, your name sounds familiar. Those pictures were intended to be temporary, they are not really high quality. I used gdl (gnu data language) to generate them, and I can give you the program, if you like. They really should be .SVG files rather than bitmap, but I haven't figured out how to generate a .SVG file from gdl yet. Im pretty sure it can be done. Let me know if you need the program. Im working on writing up different harmonics right now (cylindrical, oblate, prolate, etc.) but eventually, I will do one for the parabolic coordinates (and the parabolic cylinder coordinates as well). PAR (talk) 23:58, 17 January 2008 (UTC)

Hey PAR,

Thanks for your really nice letter! You can send any articles you like to the same e-mail address. I'd like to see the pictures you mention!

I'm ploughing ahead with making images for the other orthogonal coordinate systems. I'll try to do conical coordinates tomorrow, since they seem one of the very coolest. I like the little taco shape where the sphere and the elliptical cone intersect; it's somehow elegant, no? I just realized today that I hadn't understood even some of the basic stuff about the coordinates, e.g., that you need to eliminate the degeneracy in the bipolar coordinates. :( I should've realized that if the coordinate surfaces meet in two places, you need to take special precautions against degeneracy. For the bipolar coordinates, it turns out that σ can range from -π to π, not merely half that range as I'd originally thought; I think I was scared off by the infinity! ;) Ta-ta for today, Willow (talk) 21:39, 6 February 2008 (UTC)

[edit] MacAdam ellipse

The MacAdam ellipse delineates—not defines—the contour for the minimum perceptible distance. The concept of distance is defined by the distance metric (cf. color difference). The distance may be zero, just noticeable (JND), or anything at all. How would you draw the ellipses without the formal definition provided by color difference? That sentence is wrong. --Adoniscik (talk) 17:15, 19 January 2008 (UTC)

No, you've got it backwards. The distance metric and the Lab spaced is derived from the MacAdam ellipses. You ask how the ellipses would be drawn without the formal definition of the metric. The answer is "the same way MacAdam did". MacAdam drew the ellipses before the Lab space or the distance metric was ever defined. He chose a color specified by its CIE xy coordinates, then determined experimentally the set of colors, different from the original color, which could not be distinguished by his test subjects. These regions turned out to be ellipses, and they became known as MacAdam ellipses. The distance between any two colors in xy space was then defined to be the smallest number of MacAdam ellipses, that were just touching each other, that could be fit between the two points. To be more accurate, a metric was defined in xy space (which varied with x and y, and direction and was therefore a tensor) in which the unit of distance was the distance across a MacAdam ellipse.
The next step was to invent a new color space, a distortion of the CIE xy space, in which all of these ellipses became circles with radii equal to unity. If such a space could be invented, and "a,b" were the coordinates in this new space, then the metric tensor would be unvarying over the entire space, and the distance between two points would be just like the Euclidean distance in physical space. Such a space was in fact invented, and the new space was called "Lab" space. Its not a perfect fit to the MacAdam ellipses: The MacAdam ellipses in Lab space are not perfect circles, but its close enough. The distance in Lab space is not a definition, it is a result derived ultimately from the work of MacAdam. Actually there have been a number of attempts to invent such a space and each improvement replaces the previous approximation. Perhaps a newly concocted space will replace the present Lab space in the future, and the concept of distance will be expressed somewhat differently in that space, but before the concept of distance is redefined, a new experimental determination of the MacAdam ellipses will have to be made.
Again, the MacAdam ellipse defines the concept of distance in any color space. PAR (talk) 18:06, 19 January 2008 (UTC)
I think it would be more accurate to say "MacAdam experimentally verified that measuring difference between two colors by using the Euclidean distance (between two color vectors) in an appropriate color space agrees with intuition". He then went on to define an "appropriate" color space. Obviously, an ellipse by itself is not a distance, it's an ellipse.--Adoniscik (talk) 18:36, 19 January 2008 (UTC)
Thats really not the case. MacAdam was an experimentalist, I don't think he or anyone else was worried about metric tensors and appropriate spaces. He certainly didn't invent the Lab space, that came years later. Also, the outer boundary of a MacAdam ellipse is, by definition, at a distance of one from its center. Its just that in xy space, the space is "stretched" in some places more than others and in some directions more than others. Thats why the metric is a full tensor in xy space, and that tensor changes with position in xy space. If we had a perfect Lab space, it would perfectly "unstretch" the xy space, the distance from a point would be the same in any direction, the ellipses would become circles which were all of unit radius, the metric tensor would become the unit tensor, and the distance would be Euclidean, s^2=a^2+b^2. If you can get hold of a copy of Wyszecki and Stiles "Color Science", it is the best book on color science I have seen, and it goes through all of this in detail. PAR (talk) 19:00, 19 January 2008 (UTC)

[edit] CIE

What I did is explicitly allowed, per the page you cited: "Deleting material not relevant to improving the article". None of that stuff is relevant, so please remove or archive it. p.s. your talk page is a bit long. --Adoniscik (talk) 02:04, 19 February 2008 (UTC)

Ok,ok, I archived it :)
Regarding the guidelines, I see the line you are referring to, but I also see the first few lines IN ITALICS "Do not strike out the comments of other editors without their permission." and "Editing others' comments is sometimes allowed, but you should exercise caution in doing so". A few points:
  • I have been editing on Wikipedia for more than three years and I have never seen anyone delete whole sections of a talk page, saying they were "irrelevant". I have gotten the distinct impression that it is bad form to edit the talk page in any way except by adding material, or editing your own comments before anyone has responded to them.
  • There is no need to delete the material, it does not interfere with the article, nor does it interfere with any editors ability to edit.
  • By deleting this stuff, you make extra useless work for other editors who must scan over the entire deleted section and verify that it is in fact irrelevant.
  • Finally, in my opinion, the deleted material is not, in fact, irrelevant. Most of it is addressing article quality. It's not very useful, I agree, but it's not irrelevant. PAR (talk) 07:38, 19 February 2008 (UTC)

It's only a talk page so I'm not bothered, but the junk currently on it only confuses new editors. When I looked at the talk page I wondered why the discussion was so off-topic. If you look at the dates of the comments, you'll see they are referring to a former state of article that barely addresses the actual subject. ColorRendering and chromaticity coordinates?? —Preceding unsigned comment added by Adoniscik (talkcontribs) 09:20, 19 February 2008 (UTC)

[edit] Gas-related Articles

Hey PAR! I was wondering if you wanted to help me re-write the gas-related articles. I just finished Gas and would like you to take a look at it since I've seen you contribute a lot to these types of articles. I know you're a fan of thermo, as am I... so I figured it would be great if we could work together to make these articles actually make sense. Ideal gas is falling apart and it needs to be redone. Honestly, I feel that the thermo eqns are great but also excessive in this article. Honestly, they dont really talk about ideal gases at all... its just kind of a stand-alone "heres some thermo!" kind of thing. I think they would be better fit in a different article and just taken out of the ideal gas article.

I think the Ideal gas page should be more of a model assumption clarification more than a thermo class. so basically... when we analyze a gas, we establish a set of assumptions that we're gonna go with for the model and then do it. an "ideal gas" is just one of these assumption bases. I think this article just needs to define what these assumptions are. A separate article, Real gas, can be expanded on to include all the different types of models and lack of assumptions and all the statistical thermo and compressibility and all the magical deviations from the "ideal" model.

Please take a look at these articles and get back to me. let me know if you want to help me out! Thanks! Katanada (talk) 07:12, 26 February 2008 (UTC)

[edit] Fair use rationale for Image:Masuda2.png

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[edit] Image:Baboon24.png

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[edit] Speedy deletion of Template:CallTest

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Thanks. --MZMcBride (talk) 21:04, 23 March 2008 (UTC)


[edit] Non-free use disputed for Image:Mae_West_Signature.png

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[edit] Fair use rationale for Image:TeriCopley.png

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[edit] Replaceable fair use Image:EmmylouHarris80.jpg

Replaceable fair use

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Ok, I have done that.PAR (talk) 18:22, 22 May 2008 (UTC)

[edit] optics images

I like your image on the "real image" article. I would like to add one that I think would help the article. Can you tell me how I can upload the svg file I made? Thanks. 209.253.120.198 (talk) 01:12, 6 June 2008 (UTC)

Sure, go to the commons upload page (here) and follow the directions. Be sure to pick permissions of Public Domain-Own work. PAR (talk) 15:35, 6 June 2008 (UTC)

[edit] Speedy deletion of Image:BuffaloNYFlag.jpg

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