User talk:Mythealias/Archive 1

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Welcome!

Hello, Mythealias, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are some pages that you might find helpful:

• The five pillars of Wikipedia
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I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome! Just H 20:08, 25 December 2006 (UTC)

Bug reporting

You left the IRC channel before I could respond: http://bugzilla.wikipedia.org/ —WAvegetarian•(talk) 08:57, 19 January 2007 (UTC)

Sorry for the trouble. I had to be afk, so I logged out. Thank you for your help. myth 09:28, 19 January 2007 (UTC)

Wikipedia comments

The Comment article used to include a link to the Wikipedia commenting system within the Publishing subsection. I see that User:Yuser31415 deleted this link on 17 January. I have added the link back with, I hope, more appropriate text. I now appreciate that my revert comment was incorrect and that I should have checked that the link to the Wikipedia commenting mechanism was still there. Sorry for confusing you and I hope you are happy with the new link under Publishing. Derek farn 11:08, 20 January 2007 (UTC)

Thanks for the clarification. myth 16:21, 20 January 2007 (UTC)

lifting line theory

This topic, as a discussion of the vortex distribution over a finite wing, could possibly go on the Horseshoe vortex stub I started? Bob aka Linuxlad 13:59, 31 January 2007 (UTC)

I was trying to point out that downwash is not solely due to the wing tip vortices (as incorrectly pointed out by Jason M (164.107.199.93). Right now I am focusing on gas dynamics topics. If I find time I will try to expand the horseshoe vortex stub. -Myth (Talk) 15:02, 31 January 2007 (UTC)

Yes but I think his is the more usual usage amongst aerodynamicists (of whom I am not one). Bob aka Linuxlad 17:54, 31 January 2007 (UTC)

I was wrong on the previous count. The downwash can be attributed to the trailing vortices. Earlier I was under the impression that the bound vortex is also important, but this is not the case. By definition, the downwash is measured at the position of the bound vortex and since a straight vortex line cannot induce velocity on itself, it is incorrect to say that the bound vortex is required to determine the downwash. Sorry for the confusion. -Myth (Talk) 04:02, 1 February 2007 (UTC)

Shock Wave

Hi Myth, I left a note on the talk page. Basically I obviously didn't understand your objection. I'd like it if the shock wave/expansion wave pairing was made though. AKAF 10:49, 12 February 2007 (UTC)

Image:Phase diagram.png

Hi, I notice you replaced the SVG image Image:Phase-diag.svg with a PNG version Image:Phase diagram.png. SVG images are preferred on Wikipedia because they can be scaled, printed and edited without losing information, and can be translated into other languages much more easily (and even automatically). I'll edit Image:Phase-diag.svg to add your improvements, but in future when you wish to improve diagrams which are currently in SVG it would be better if you were to edit them yourself. There exist free (and very good) SVG editors; I recommend Inkscape. –EdC 14:33, 25 February 2007 (UTC)

Thanks for the suggestion. I will try using some SVG editor for future edits. -Myth (Talk) 04:01, 26 February 2007 (UTC)

Period

Thank you for your fix at the Conjugate gradient method page. I put back a period you removed, since per math style manual, there's got to be a period at the end of formula if the formula is at the end of sentence. Cheers, Oleg Alexandrov (talk) 18:27, 3 March 2007 (UTC)

I did not realize that. Thanks for the letting me know. -- Myth (Talk) 19:50, 3 March 2007 (UTC)

40% Efficiency?

In the example experiment starting with "A closed cylinder with a locked piston contains air...", is there a reason why 40% of the heat is transferred into work (as opposed to 50% or some other value)? Can this be thought of as the efficiency of the process in terms of converting heat into work?

The article was very comprehensive, but I was a bit puzzled as to why 40% was the magic number. Thanks, -Paul

I guess you are referring to the Heat capacity ratio article. The 40% number is because the value of heat capacity ratio ($\gamma$) is 1.4 for air (refer to the table in the article). Since the amount of energy added under the two conditions is proportional to $C_{V}$ and $C_{P}$ respectively, the excess energy added for the second case will be proportional to ${\frac {C_{P}}{C_{V}}}-1=1.4-1=40\%$ and hence the number 40%. If the cylinder was filled with some other gas, say Helium (He), then the value would be 66% instead of 40% or 30% in case of ammonia (NH₃).

btw it is not correct to think of this excess energy added to the system as efficiency of a process while converting heat to work. The excess energy can be added either as heat (as mentioned in the article) or by doing work on the system. In either case the number will be 40% for air.

I hope this helps. -- Myth (Talk) 14:04, 17 May 2007 (UTC)

Followup

Thanks for the response. I was wondering if you had some insight into how one should think about the allocation of energy between work and temperature increase when an ideal gas is heated at constant pressure (i.e. in a vessel with a movable piston)? Some of the heat is converted into work, but what governs how much heat actually gets turned into work? — Preceding unsigned comment added by 24.215.227.43 (talk) 01:41, 18 May 2007 (UTC)

The example mentioned above is trying to show that. To increase the temperature of a system (in this case a gas at constant pressure), one needs to provide some energy to it. However since we want to keep the pressure constant, the system will have to expand (increase in volume) to allow for temperature increase. So it will require extra energy than the case when the system was held at constant volume.

Consider this analogy. Say you have a tank with some water. There is an inlet tap to fill it and an outlet tap to drain it. If you want to increase the level of water in the tank, you need to open the inlet tap. However if you also open the outlet tap, it will take longer to increase the level of water by the same amount. Here the water is like energy and the tank is your system. If you open the inlet tap, it's like adding energy to the system. A constant volume system is same as one with outlet tap closed. If the outlet tap is open (a constant pressure system) the tank is providing some water (same as system doing work on the surrounding).

This example does not care how much heat is converted to work and vice versa. All it says is that if the system is doing work on the surrounding than it will require more energy to increase it's temperature. Heat and work are two was in which energy is transferred to a system. Temperature of a system is a measure of energy stored in the system (usually called thermal energy). This energy can be extracted as work or heat. Only a certain amount of this energy can be used to perform work. This is usually explained in terms of a heat engine. There are different types of heat engines, each with it's own efficiency. In case of gases, the most efficient one is the Carnot heat engine. -- Myth (Talk) 00:11, 19 May 2007 (UTC)

Oh My Goddess!

A goddess descends to your talk page

Hi, I noticed your username appears on this category and would like to invite you to take part in a general improvement drive on all articles relevant to Oh My Goddess! including character articles, episode articles and others. -- Cat ^chi? 21:53, 9 October 2007 (UTC)

Thanks for the invite. But I am bit caught up these days. I will try what I can do. Thanks. -- Myth (Talk) 23:35, 18 October 2007 (UTC)

Aerodynamics

Hi Myth. EMBaero is having a go at cleaning up some pages in the aerodynamics sections, so not would probably be a good time to lob in, if you're so inclined. Amongst other affected: Oblique shock, Moving shock, Shock wave, Shock dynamics, Rayleigh_flow, Fanno flow and Prandtl-Meyer_expansion_fan. Regards AKAF 15:44, 18 October 2007 (UTC)

Thanks for the notice. I will keep that in mind. -- Myth (Talk) 23:38, 18 October 2007 (UTC)

Myth, Excellent job on updating the Oblique shock diagram. Most of the incorrect edits by Genick and his alternate identity 209.32.159.25 have been taken care of. Perhaps this will lead the way to some better aerodynamics articles - there are only a handful that are up to B class. I am going to work on Fanno flow and Rayleigh flow until they have some reasonable depth. Oblique shock can be expanded more in the future, but it might be more important now to upgrade the very important articles like Compressible flow to an acceptable state. EMBaero 01:23, 28 October 2007 (UTC)EMBaero

How to use Popups for reverting vandalism

Greetings, Mythealias: I have noted that you use Popups to revert vandalism ... and I would like to learn how to do that. Would you be so kind as to explain it to me, step-by-step? Thanks in advance and regards, - mbeychok (talk) 18:48, 23 November 2007 (UTC)

Please refer to Wikipedia:Tools/Navigation_popups/FAQ#How_do_I_revert_using_popups.3F for the details. You amy also want to refer to Wikipedia:Tools/Navigation_popups for details regarding popups and Wikipedia:Tools/Navigation_popups/Edit_summary_options to add options to your popup menu. I had added the following code to my javascript page for the popup options,

//---------------------------------------------------------------------------------------
// See for details.
// User:Lupin/popups.js
 
importScript('User:Lupin/popups.js');
 
// simplePopups=true;            // Just load the links, no preview of the article.
// popupFixRedirs=true;          // Option to fix redirects. Not recommended.
popupSubpopups=false;         // No popup links during preview.
popupMaxWidth=500;            // Max width (default 350).
popupRevertSummary='Reverted edits by [[User:## |]] ([[User Talk:## |talk]]) to last version by [[User:## |]] using popups';
popupRevertSummaryPrompt=true;
 
//---------------------------------------------------------------------------------------

I have turned on the edit summary prompt to change the summary in case there is a need to explain the revert.

If you still have questions, you are more than welcome to ask me. -- Myth (Talk) 01:13, 26 November 2007 (UTC)

Thanks very much! I have installed it and it works very nicely. I do have one more question: Can it be set to revert back further than simply reverting the last edit? In other words, if there were say 3-4 vandalisms before I saw them, can Navpop revert all of them at one time? ... or only 1 at a time? - mbeychok (talk) 17:59, 26 November 2007 (UTC)

Just hover over the diff for the earliest edit that need to be reverted or the link to the version you want to revert to. I have not tried it, but I think it should be possible. For some reason my navpop don't seem to work on this computer, so I am not able to check it out. Let me know if it works for you. Thanks. -- Myth (Talk) 20:39, 26 November 2007 (UTC)

Static pressure

Hi Myth. I am impressed by your work in this field so I am writing to you to ask your assistance. I see some problems with Static pressure so I used the discussion page to initiate a debate. I would appreciate it if you would peruse the discussion page and add your comment. Regards Dolphin51 10:56, 4 December 2007 (UTC)

Hi, thanks for inviting me to the discussion. I have read through your discussion and will add my comments to it. Right now I am busy in the real-world, so it might take some time. -- Myth (Talk) 15:00, 5 December 2007 (UTC)

AFR

Does the "ideal" ratio of 14.7:1 pertain to using a gas?

Thanks,

Msolq (talk) 23:01, 8 January 2008 (UTC)

No, one can define AFR for any state, there is no relation to the state of the fuel. btw i am not sure where the word "ideal" ratio comes in ? The Air-fuel ratio article mentions

For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7 times the mass of air to fuel.

but this is specific only for gasoline and there is no reason to use the word "ideal". -- Myth (Talk) 20:05, 12 January 2008 (UTC)

Speedy deletion of Template:Engineering fundamentals

A tag has been placed on Template:Engineering fundamentals requesting that it be speedily deleted from Wikipedia. This has been done under section T3 of the criteria for speedy deletion, because it is a deprecated or orphaned template. After seven days, if it is still unused and the speedy deletion tag has not been removed, the template will be deleted.

If the template is intended to be substituted, please feel free to remove the speedy deletion tag and please consider putting a note on the template's page indicating that it is substituted so as to avoid any future mistakes.

Thanks. --MZMcBride (talk) 03:47, 3 February 2008 (UTC)

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