User talk:Adrian de Physics/Archive 1

Hi! I'm not formally offering to adopt you because I just made an offer to adopt someone else and I don't want to make commitments I might not be able to fulfill. However, you're welcome at any time to ask me for help whether you're adopted or not. I just created a page for you here: User:Adrian de Physics/Acoustics draft. The page is in your userspace. You can use it to play around with and to put your draft article. I suggest clicking edit and then using the mouse to copy and paste your draft article in. If you ever want to delete that page, you can put on it  for deleting a page in your userspace. If you load in your draft article, I can help you fix it up and then move or copy it to the encyclopedia mainspace. (Mainspace means regular articles, pages that don't have "User:" or "Talk:" or something in front of the name, and that show up in search engines.) You can reply here or at my talk page. --Coppertwig (talk) 16:46, 26 December 2007 (UTC) Thanks Coppertwig ! Your help much appreciated. You have given me some good pointers to be working on. Meanwhile I looked up some of the other topics adjacent to those of the article I am fixing to write, have in mind, found that some were excellent and best left alone, some were marked as stubs, some had spots I would be tempted to improve, etc. so there's lots to do. I just need to work up to it bit by bit. I will plan some crosslinks offline and have them ready before trying to get my article up. My general web experience is very limited and I want to strengthen it, that's part of my motivation for doing this. I took a look at your site but had better get practice at editing this one before I make an appearance on yours. I can see you are very active / not to say prolific / in this world so thanks again for your offer ! Adrian


 * Hi! Nice to hear from you. For detailed help on how to do links, see Help:Link, but it's really very easy.  To link to a page, just put two sets of square brackets around the page name, like this:    Acoustics    which looks like this:  Acoustics.  So you can just put double square brackets around   some words or phrases in a sentence, and if there's a Wikipedia page with that name, it will link to it.  If there isn't, it will look red.  There are more complicated ways to do it, but start there.  It doesn't matter whether the first letter of the first word in the title is uppercase or lowercase.


 * Here's some introductory information to help you:

Welcome!

Hello,, 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: I hope you enjoy editing here and being a Wikipedian! Please sign your messages on discussion pages using four tildes ( ~ ); this will automatically insert your username and the date. If you need help, check out Questions, ask me on, or ask your question and then place  before the question on your talk page. Again, welcome!
 * The five pillars of Wikipedia
 * Tutorial
 * How to edit a page
 * How to write a great article
 * Manual of Style


 * If you load your draft into that userpage I made for you, let me know whether you'd like me to help edit it right away, or not. (Once you put it into the main article space, anyone's free to edit it.)
 * On a talk page such as this one, when you start your message, hit the "return" (or "enter") key once or twice so you're starting at the beginning of a new line, rather than adding to the end of the previous person's message. At the end of your message, put four tildss, like this:    ~     and when you save your edit, the server will replace the tildes with your signature and the date.  On an article page, (or on that draft page,) don't sign.  And don't worry.  You're allowed to make mistakes. --Coppertwig (talk) 03:19, 27 December 2007 (UTC)


 * By the way, I encourage you to experiment: type a few words with double square brackets around them, for example.  You can experiment here on your talk page, or on the draft page, or in the sandbox.  You can also experiment by just clicking "show preview" rather than "save page", so you can see just what your edit will look like, without actually changing anything on Wikipedia.  Actually, it's a good idea to get in the habit of clicking "show preview" before saving.  --Coppertwig (talk) 03:39, 27 December 2007 (UTC)


 * I see you've uploaded your draft. Lots of good material there!  Would you like me to make suggestions for edits, (or even edit it directly), or would you prefer to work on it yourself for a while first?


 * At first I was baffled why the square brackets on "elastic waves" weren't working, but I guess you can't use square brackets inside other square brackets.


 * OK, now that you know how to do simple links to other pages, the next step is: how to link when the way the words appear in your sentence are different from the name of the page you want to link to.  It's not that much harder.  You just put the real name of the page first, then a pipe character | then the words you want to see in your sentence.  For example, if you want the word "ellipticity" to link to the page "ellipse", you can write  ellipticity     and it will display as ellipticity.


 * For elastic waves: if you want to link to both pages, the elastic wave page and the wave page, you could have the word "elastic" link to one page and the word "wave" to the other, like this:     Elastic waves     which looks like Elastic waves.  But that may be confusing to the reader, because it looks like just one link.  Another way is to make "Elastic waves" link to one page, and then the next time the word "wave" or "waves" appears in the article, make it a link to the other page.  --Coppertwig (talk) 19:32, 27 December 2007 (UTC)

Just saw that you have been watching over this like a guardian angel ! Thanks ! Working on the references has helped me to tweak the text so as to refer to the best stuff and not to wikis that are questionable or embryonic or under debate. That's why in the most recent I am not trying to reference "elastic waves" any longer. One day maybe when that area itself is stabilized. I gotta read your other tips now, just wanted you to know I have seen you and am catching up. Adrian Pollock (talk) 19:44, 27 December 2007 (UTC)


 * It can actually be good to link to embryonic pages, in my opinion, if they're on topics that deserve to be expanded. It helps people find those pages, and likely some of those people will add to them, bringing them out of their embryonic state.  It's even fine to (occasionally) have (a small number of) red links, that is, links to articles that don't exist yet. But for now that's up to you. --Coppertwig (talk) 20:07, 27 December 2007 (UTC)

OK, I will bear that in mind. There are other people currently discussing whether "elastic waves" should be merged into "elasticity". I might have something to say about that but want to focus on getting this article published first. The hierarchy is waves > (mechanical waves) > elastic waves > Lamb waves and ideally that'd be clean and clear for the readers of all the articles. But I suppose you will respond that it's a web as well as a hierarchy. . . :)

These are the things I still want to do / question on the article -

1. Fix one of the references

2.   Does the list of references get a different formatting ? Is the list of references a footnote ?? Need to find out how to refer to a reference from the text. 3. Additional line spaces between the paragraphs.

4. One diagram (it's too dry without any). It will be pictures of the two modes (curvy lines). Will it take an Excel chart ? Or a .jpg file, not sure how I'd get from an Excel chart to a .jpg file ? Then there's the layout and captioning of the diagram in the article. This is where perhaps you could help me directly and save a bunch of time.

5. With the above done, plus any other tweaks I might notice, it would be basically ready to publish as far as I'm concerned so Coppertwig, your edits and suggestions would be very welcome prior to putting it into the main article area.

It'll take me a while to work on the diagram. I'll check back here in a while, not sure what's going to happen with the rest of today. I know I could probably find answers to some of the above in the references but the wheels tend to spin and it's sure helpful having you looking over the shoulder !

Adrian Pollock (talk) 20:47, 27 December 2007 (UTC)

replying

 * Images: Here's an example of how to display an image. (Thumbnail size.  Reader can click on it to see larger version.  There are other ways to do it.)


 * Well, that image has a filename ending in .jpg, so I guess .jpg are fine! Normally, at least for images you produce yourself, you upload the image to Wikimedia Commons.  You need to create an account there.  You can use the same username if it isn't already taken.  I haven't uploaded any images so you may need to ask for help from someone else.  When you upload the image, you have to include a statement that you own the copyright and that you release it under such-and-such free license -- you probably need to read instructions on what licenses are OK and what exactly you need to say.  First steps should help you get started at Commons.  Once you have an account, have read some instructions and want to upload a file, try Upload.  Once your file is uploaded to Commons, you can easily display it on your Wikipedia page the way I just displayed Iapetus.  I probably ought to start uploading images myself.


 * Whether they take Excel files I don't know, but Commons:Software at Commons mentions a program to convert excel to jpg. (On many browsers, use control-f to search for a word on a page.  Search for "excel" on that page to find it.)


 * Ah, you found out about


 * There are different ways to arrange things. Some articles have a "bibliography" etc.  I suggest that the simplest way is to cite each of the books using cite the same book more than once like this. (First one uses ;  second  or subsequent one merely needs  .  Note that there is a slash at the end of  and it doesn't need a separate closing tag.


 * Optionally, you can use Template:Cite book to format your citations. I usually do that.   I go to the template page and copy-and-paste the following:   .  Normally I also put that whole thing inside tags.  Then I fill in the various fields such as title of the book etc.  Just paste the information immediately after each equals sign.  I don't think it matters where spaces go.  You can leave some fields unfilled and it will still display fine.  There are also other optional fields you can add in, such as |pages= and |quote=.  See the template page for complete instructions.


 * If you want more spaces between the paragraphs, just hit "enter" a couple of times to insert blank lines. There's probably a standard amount of space usually used in Wikipedia articles between paragraphs, but I get a little confused about whether it's zero or one blank line (or possibly two).

Dividing a page into sections with section headings

 * It would be a good idea to divide the article into sections. The first section is (lead) introductory with no section heading and should tell what Lamb waves are and set them in context.  For other sections, you can create headings by putting a heading on a line by itself with two equals signs before and after it.


 * Sorry, you already knew how to put headings. But, no heading is needed at the very beginning of the article.   The first sentence should include the phrase Lamb waves in bold type which you get by using three apostrophes like this.


 * Are you making this assumption: "The fundamental "linearizing" assumptions of linear elasticity are: "small" deformations (or strains) and linear relationships between the components of stress and strain." (quoted from the Linear elasticity page).  If so, maybe that has to be made clearer (than it was in your first draft -- I haven't studied your most recent changes in detail.)  --Coppertwig (talk) 21:54, 27 December 2007 (UTC)

math symbols and other stuff
See Help:Displaying a formula. For example, :$$\beta = f(x^2)$$, which gives
 * $$\beta = f(x^2)$$

The stuff that goes between the math tags is LaTeX (which is similar to TeX).

Try starting the article with a sentence beginning "Lamb waves are...". The following paragraph may be good to move up to form the first or second paragraph, since it helps define them:


 * {|border = 1


 * "Lamb’s characteristic equations were the solution of a classic eigenvalue problem. They constitute a complete, orthogonal and orthonormal set of eigenfunctions for waves propagating in a plate having motion in the direction of propagation (x-direction) and in the direction of the plate normal (z-direction). By definition, Lamb waves have no particle motion in the y-direction. Motion in the y-direction in plates is found in the so-called SH or shear-horizontal wave modes."
 * }
 * "Lamb’s characteristic equations were the solution of a classic eigenvalue problem. They constitute a complete, orthogonal and orthonormal set of eigenfunctions for waves propagating in a plate having motion in the direction of propagation (x-direction) and in the direction of the plate normal (z-direction). By definition, Lamb waves have no particle motion in the y-direction. Motion in the y-direction in plates is found in the so-called SH or shear-horizontal wave modes."
 * }

It might help to define a "plate" something like "a region of three-dimensional space bounded by two parallel planes". There are two types of Lamb waves; how many other types of (non-Lamb) waves are there that propagate in plates? Only one other type (i.e. SH waves)? Are SH waves entirely in the y-direction or do they have some x and z motion too? I wonder if a mention of Lg waves (in seismology) could be fit in, too. I see that the seismic waves article doesn't mention Lg. Maybe it would make more sense to mention them there but not here, I don't know.

Perhaps "midplane of the plate" needs to be defined, too. I presume you mean "a plane in the centre of the plate, parallel to its sides." The first time I read it I was imagining a plane perpendicular to the sides of the plate. --Coppertwig (talk) 03:06, 28 December 2007 (UTC)

Ooh! I see you got your image uploaded! Congratulations! You're ahead of me on that one. It looks good. --Coppertwig (talk) 03:09, 28 December 2007 (UTC)

Thanks very much for the Greek letter info. That's right on my critical path. After that I'll take a look at your suggestions. I can see you are into this technically as well as editorially - great ! Adrian Pollock (talk) 03:17, 28 December 2007 (UTC)


 * ... or "a solid bounded by two parallel planes" or "an infinite solid bounded by two parallel planes" or something. --Coppertwig (talk) 03:28, 28 December 2007 (UTC)

OK it is largely cleaned up now and while I ponder your comments can I ask your opinion no two details -

1. I succeeded in linking to the video of the wave motion, it is really an outstanding piece of work by the person who put it together. Would it be proper web etiquette to find this person and let him/her know we are linking to this page ? I'm not familiar with web etiquette but I did hear this somewhere.

2. There are two websites listed at the end, they are not classic sources like the main references; do you think it is worth including them or should we let them go ? After all, anybody can google.

Meanwhile I've addressed most of your suggestions in text revisions and see it's the better for that. For example I tried "midthickness plane" instead of "midplane", does that work better ? On some of your other thoughts -

1. lg waves, I'm wasn't familiar with these until you raised it. Looked around and suggest let's leave this one to the seismologists ! It sounds like an indication that they observed in their seismograms and have named but are having difficulty explaining in terms of well-understood wave types. Time will tell.

2. Seismology is a great field but I don't want to mix it in with this article on Lamb waves because the earth is essentialy no-surface or one-surface whereas the plate is essentially two-surface.

3. Regarding linear vs non-linear elasticity, I did put the word in but I don't want to make a lot of it - in the acoustics trade we routinely assume linearity, treating non-linear acoustics as a specialty in its own right. 5. Re breaking it up into sections. I can see this is the best way to set up an articler for future editing by many people. Alas I wasn't thinking of this early on, so I wrote a fairly connected essay. What say you my essay is put up as an "overview" and some other sections are identified to encourage separate elaboration of various aspects ? This is how the latest draft is set up, what do you think ?

Adrian Pollock (talk) 08:04, 28 December 2007 (UTC)

PS Friday I am planning to go into work but should be back on this in the evening and over the weekend. Great if we can wrap it up and get it published with your help & blessing. How to create "new" pages is still outside my ken.

Friday evening - I have added several short sections which will hopefully provide a base for others to expand specific areas without upsetting the balance of the overview. Hoping to get it into the main space during the upcoming weekend (not sure how to do that, at this point). Do you have an opinion about those two hanging references ? - Plus your further comments on any other aspects much appreciated ! Adrian Pollock (talk) 06:36, 29 December 2007 (UTC)

Title of article etc.
Ah, I see you figured out how to link to my userpage.

Note that the title of your article could be "Lamb waves" with a lowercase w, but I don't think uppercase W would fit Naming conventions.

Note these articles, which your article should probably link to: Waveguide and Waveguide (acoustics). There may be some overlap between the articles, too.

More later. --Coppertwig (talk) 23:12, 29 December 2007 (UTC)

Re this sentence: "The nature of flexure (bending) is such that the wave velocities in this regime are proportional to the square root of the frequency, the group velocity being just twice the phase velocity."  I'm guessing that perhaps you need to make some assumptions about the nature of the material to come to this conclusion. If so, the assumptions should be stated. What properties of the material are involved in Lamb waves in general (e.g. density, shear modulus, Poisson's ratio?) Are only some of these properties involved in the lowest (flexural) mode?

Re the diagram: The top half of the diagram looks intuitively appealing, but I'm not yet convinced about the bottom half. For one thing, the ratio of plate thickness to wavelength looks perhaps smaller than possible. (What is the smallest possible value of this ratio?) For another thing, it looks as if a vertical slice through the plate would encounter a set of particles all of which have the same displacement at a given time. It seems to me that if so, then that's true only for this one type of lowest mode and not for any of the higher modes. If true, perhaps you could mention that. A diagram showing a higher mode would be good, or if not feasible, then perhaps a description in words. I'm guessing that in the higher modes, a vertical slice through the plate at a given point in time goes through a number of regions of alternately positive and negative displacement, with the number of such regions getting large a high-order modes.

Once the frequency is high enough for a given mode to be possible, does that mode exist only at that particular frequency, or does it exist for any of a continuous range of frequencies starting at the lowest possible frequency for that mode and extending, in theory, to infinitely high frequency?

I was thinking of guided waves as in electromagnetism and wondering how they differed from Lamb waves. The current version of your article gives me this information: that Lamb waves involve shear waves (SV, not SH) as well as pressure waves, while electromagnetic waves have only one type (analogous to pressure waves, I guess). It might possibly be good to move this information a little closer to the beginning of the article and to mention guided waves in electromagnetism as a contrast. --Coppertwig (talk) 00:35, 30 December 2007 (UTC)

Creating a page
Creating a new article page is very easy, actually. I recommend that for this article, you first save a copy of it on your own computer to cover the unlikely event that the article gets deleted. (I don't think there's any valid reason to delete it.) If people edit it, you can still find your earlier version in the edit history. But if it gets deleted (very unlikely for this article, I believe -- though about 3/4 of new articles are deleted I think; most of them are not of this quality), then you can't see the history either.

When you're ready to move the article to article space, go to your draft page, and you should have a tab labelled "move" at the top of the page, to the right of the "edit this page" tab etc. Click "move" and it will prompt you for the new name. Just put a name like "Lamb waves" (or whatever name you think is appropriate) and move the page. Remember to use a lowercase w in waves. Names that don't start with "User:" or "Talk:" or "Wikipedia:" or "Help:" etc. are article pages.

You can do this move any time you want. You can continue to edit it after moving it to the main article space.

To create other articles, an easy way is to edit some page to create a link to a nonexistent page with the name you want. The link will show up as a red link. Just click on the red link, and it will give you an option to create the page. NOTE: I recommend that you do not use this method for Lamb waves, since you already have a draft. In that case, it's better to "move" your draft, because it will move the whole edit history too. If you were to create the page some other way, then you would no longer be able to "move" the page unless you first got an administrator to delete the new, blank page at the name you want.

The titles of the subsections should have lowercase letters for all but the first letter, except for names etc.

The article looks very good to me. I'm learning from it. I may still ask you some more questions. Hopefully my questions can help you improve the article as well as informing me.

I agree with you that Wikipedia is great. An excellent source of information, and an excellent way for large numbers of people to cooperate together. It still needs a lot of work to make it even better. Thanks for your contribution. I hope you enjoy contributing and continue to contribute. --Coppertwig (talk) 00:57, 30 December 2007 (UTC)