User talk:Crowsnest

DYK for Morison equation

On February 20, 2009, Did you know? was updated with a fact from the article Morison equation, which you created or substantially expanded. If you know of another interesting fact from a recently created article, then please suggest it on the Did you know? talk page.

--Dravecky (talk) 05:53, 20 February 2009 (UTC)

Edit warring

Hi Crowsnest, I'm sure we both mean well. Shall we talk this over? Constructive editor (talk) 22:45, 22 February 2009 (UTC)

Sure. Regarding non-dimensional and dimensionless: that is just the same and can stay as it is.

Regarding Abdul Ahad: he is not-notable, nor his constant. Peer-reviewed scientific articles (as required for such a scientific term) are lacking. Even if one or two existed, that still would not be enough since that would give this insignificant material an undue weight in the articles. Abdul Ahad himself being not notable enough for inclusion in WP, certainly is not a famous astronomer. -- Crowsnest (talk) 22:54, 22 February 2009 (UTC)

Dimensionless it is then :)

I don't buy that this guy is not notable for wikipedia; He's published for one thing, has had massive amounts of publicity in third party sources covering radio, TV and newspapers, has had his books reviewed in independent sources, etc. There are many, many people listed in thousands of articles strewn across Wikipedia that are redlinked on whom you may not get a single reliable source. So I struggle to understand why he is being singled out and attacked in this way. The Ahad's constant is a fundamental scientific phenomenon measuring the universe's background light flux [1] incident upon the earth - named after him - that's out across the internet. It is the constant of electromagnetic flux incident upon the earth when one excludes the solar constant. To refuse him a position here seems to me a pity considering his achievements as both an author and a budding astronomer. Constructive editor (talk) 23:09, 22 February 2009 (UTC)

Your ref to http://www.astroscience.org is just his own website, so a primary instead of a secondary source, see WP:PSTS. I would expect a renowned astronomer to have published several papers in peer-reviewed scientific articles. Also have a look at WP:ACADEMIC for notability requirements regarding scientists. Best regards, Crowsnest (talk) 23:17, 22 February 2009 (UTC)

With respect to Ahad's constant in Apparent magnitude: it is not a celestial object, as what is the subject of the list.

With respect to Scientific phenomena named after people: a significant amount of reliable secondary sources (peer-reviewed scientific articles) by others than Ahad himself should refer to Ahad's constant, before it is notable enough to be considered one of the "scientific phenomena named after people" in this list. This is not the case. -- Crowsnest (talk) 00:46, 23 February 2009 (UTC)

I asked for input from others at Wikipedia talk:WikiProject Astronomy#Abdul Ahad. -- Crowsnest (talk) 02:06, 23 February 2009 (UTC)

That sounds a good idea Constructive editor (talk) 06:36, 23 February 2009 (UTC)

WP:PHYS tagging.

Hello Crowsnest,

First thanks for tagging that bunch of articles for WikiProject Physics and its Fluid dynamics taskforce. Just a reminder to please give them class and importance ratings, it really helps our effort to keep track of the quality of articles in our projects. (I gave them ratings, if you disagree with them, simply change them).

Second, since you've tagged a bunch of fluids dynamics-related articles, I'll have to ask you if you happen to know anything about fluid dynamics? There's a big gap at the physics project when it comes to fluid-dynamics, most people seem to have a background in particle physics and QM. If you are, we'd all really appreciate it if you joined us and the Fluid dynamics taskforce (which is almost completely inactive due to lack of experts). If you know of other people interest in physics and fluid dynamics (in and out of wikipedia), could you let them know about the physics project and fluid dynamics taskforce?

Third, a lot of these article you just tagged seemed of pretty good quality. If you are involved with them, have you considered nominating one as a Good article or Feature article? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:10, 23 February 2009 (UTC)

Hello Headbomb! Thank you for assessing all these thousands of physics articles the last half year! In reply, using your numbering:

1. I will do that in the future. The reason, why I did not give them a rating, is that I created or heavily edited a significant portion of the articles I tagged. That made me reluctant.
2. Yes, I have a background in fluid dynamics. I will contact some more WP editors who know about the subject and see if they are willing to participate. If there is interest by some others as well, I am willing to help revive the fluid-dynamics task force.
3. No, I have not considered nominating them as good or featured articles. Although I see that such a review process has its strong merits, I do not think that is what I would like to do at Wikipedia. It would easily give me too much stress. -- Crowsnest (talk) 09:34, 23 February 2009 (UTC)

Fluid Dynamics Taskforce

Hi Crowsnest, thank you for inviting me to join the Fluid Dynamics Taskforce. I will be glad to join the task force and do whatever I can do to improve the fluid dynamics related articles. Salih (talk) 16:42, 3 March 2009 (UTC)

Great, and welcome! You can add your name to the list of participants, see WP:FLUID. -- Crowsnest (talk) 16:56, 3 March 2009 (UTC)

Quaternions

History of quaternions is now a redirect. You have more familiarity with the literature than I do; if you feel like writing a decent article, please feel free to start on this tabula rasa. I also started a conversation on Talk. Septentrionalis PMAnderson 23:45, 4 March 2009 (UTC)

No, I just did a simple Google Books and Google Scholar search, and had a look at some of the references that came up and seemed worthwhile. I have no further direct affinity with, or knowledge of, the subject (more with Hamiltonian mechanics, as far as Hamilton is concerned). Thanks for removing the garbage! -- Crowsnest (talk) 23:54, 4 March 2009 (UTC)

You have the titles, at least; that's more than I do. But I don't mean to volunteer you into writing an article, although you may want to keep an eye on the discussion at Talk:History of quaternions#redirect, to see what the enthusiast says. Septentrionalis PMAnderson 23:58, 4 March 2009 (UTC)

I have it on my watchlist. Best regards, Crowsnest (talk) 00:02, 5 March 2009 (UTC)

wolff algorithm

Thanks for adding references and cat to wolff algorithm. --MarSch (talk) 00:13, 10 March 2009 (UTC)

I liked to do it. -- Crowsnest (talk) 07:25, 10 March 2009 (UTC)

New sources

I don't know whether you are watching Wikipedia:Articles for deletion/Kuessner effect, but new sources are available. Cheers. --Edcolins (talk) 22:16, 10 March 2009 (UTC)

Thanks for pointing out. Are you acquainted with this effect? Can you help to adapt the article? Best regards, Crowsnest (talk) 22:55, 10 March 2009 (UTC)

Sally Mann

Thanks for the post submission editing as well as the pre...

I had trouble finding what {refbegin} and {refend} did. Is the only thing it does is change the size of the font? Zipity11 (talk) 11:24, 13 March 2009 (UTC)

Yes. It makes the same font size, in between the tags {{refbegin}} and {{refend}}, as used in the footnotes. If you do not like, you can just remove it. -- Crowsnest (talk) 11:28, 13 March 2009 (UTC)

Momentum - lift relationship

Is this correct, for potential flow theory? :

Sectional Lift = - dP_y/dt

where P is the limit of the total momentum (double integral of momentum over the region) enclosed by a circular region with some part of the wing at its center, as the radius of the circle goes to infinity.

If so, then I understand what the articles mean when they refer to the change in vertical momentum of "the air" associated with lift.

Basically, "the air" would mean "all the air". The use of the limit would make the derivative into a finite quantity, even though the total momentum of the air is infinite. Mark.camp (talk) 20:49, 17 March 2009 (UTC)

The problem is, that the momentum change as you depict it: the rate of change of the vertical momentum in a fixed region R, in a frame of reference moving with the wing, is zero! The vertical momentum in the region is:

$P_{y}=\iint _{R}\rho v_{y}\;dx\;dy.$

Since in this reference frame ρ and v_y are time-independent, while also the region R is time-independent, the result is that P_y is time independent: dP_y/dt=0. The problem is due to the fact, that the boundaries of the region are not closed: vertical momentum can be transported through the boundary of the region. In front of the wing (the side where the air is coming from, in this reference frame) this is not a problem, since there v_y is zero (assuming that the x-axis corresponds with the incoming flow direction). But at the back, the outflow side, the wing has induced a downwash (downward directed v_y). And this vertical momentum ρv_y is transported out of region R with velocity v_n (which is the velocity component normal to the boundary ∂R of R). So there is a flux of vertical momentum out of the region R, with boundary ∂R, equal to

$\oint _{\partial R}\rho v_{n}v_{y}\;ds,$

which is balanced by the lift. The Landau & Lifshitz reference in lift (force) does this, relating the lift to the flux of vertical momentum through a vertical boundary behind the wing (then v_n=v_x. This all has to do with the difference between Lagrangian and Eulerian coordinate systems in fluid dynamics. The form of Newton's 2nd law you depict is valid in a Lagrangian frame of reference (with a region Ř(t) and its boundaries moving with the flow). While in the Eulerian frame of reference (a fixed region w.r.t. the wing) the approach is as sketched above. See also Reynolds transport theorem. I hope this does not confuse you even more. -- Crowsnest (talk) 23:55, 18 March 2009 (UTC)

Thanks much. Yes, it's obvious now to me that in this frame, the momentum in any finite region doesn't change wrt time. I will study the rest of your note and then see if I can understand it. Mark.camp (talk) 02:13, 20 March 2009 (UTC)

I realize that I didn't describe the momentum I was thinking of clearly. I refer to the limit of the momentum P_yn in a body of air which at time t₀ is enclosed by a region R_n, where R_1,2,...n is an infinite series of successively larger regions. The boundary of this body changes in time, regardless of choice of Lagrangian or Eulerian frame. I think that this dP_y/dt might be non-zero, and identical in either frame.

Is it this momentum which is meant when stating that lift is proportional to time derivative of P_y? Mark.camp (talk) 12:01, 21 March 2009 (UTC)

New article

Hi Crowsnest...

Oh, the disadvantages of your being so helpful...here I come again with hand outstretched.

I have created a new article on a local garden. You can find it on my user's page 'Alternative Sandbox'. I think I did okay [said with a muted tone of exhuberent hubris in the voice].

I would appreciate anything that you can say about it.

Thanks in advance.

Zipity11 (talk) 19:26, 19 March 2009 (UTC)

Just that it is really beautiful (both the garden and the article). Seems a very well done article to me, ready for article mainspace. Best regards, Crowsnest (talk) 23:58, 19 March 2009 (UTC)

New Article

Thanks...will put it up. Zipity11 (talk) 01:21, 20 March 2009 (UTC)

Andrew John Bevolo

You tagged "Andrew John Bevolo" for speedy deletion. It is about the founder of Bevolo. Jackroven (talk) 17:46, 21 March 2009 (UTC)

Yes, because there were no indications of notability. I searched the web (e.g. this news search), but did not find reliable sources to back up his notability. However, the company is notable (I added a reference to the article), so the administrator (Bettia) who handled the speedy deletion request turned the page into a redirect to "Bevolo Gas and Electric Lights".

P.S. The custom is to add new sections to the bottom of the talk page. This is done automatically for you, if you click the "new section" tab, which is visible on the top of talk pages (not on articles).

Best regards, Crowsnest (talk) 03:19, 22 March 2009 (UTC)

P.P.S. If you create a new article, it is handier to use "copy and paste" instead of the move of your user page. This move changed your user page, as well as your talk page, into a redirect. That made the messages I — well actually the tool I used when proposing the speedy delete — left on your talk page invisible until I removed the redirect. You can create a new article in article space by typing the desired page name in the search box at the left and pressing the Go button. If it not already exists, a search page pops up containing a red link "Create the page", which you can press to create the page (surprisingly). And just copy your text there.

It is very handy though, as you did, to first create the article in your user space. Easiest is to create a sub-page to your user page, e.g. a user sandbox like User:Jackroven/Sandbox. -- Crowsnest (talk) 03:42, 22 March 2009 (UTC)

references in OS equation

Hi Crowsnest,

Many thanks for the improvements you have made to several of the articles that I have written. I was wondering, where or how did you find the references to the original introduction of the Orr--Sommerfeld equation by Messers Orr and Sommerfeld? Are they available anywhere? The Royal Irish Acadamy only has recent copies of their proceedings online.

Cheers,

Onaraighl