Arnero

Hard to remember

Umbruch für Text und Bilder

Free_electron_laser

Which numbers are wrong? Before your edit [1], the article didn't contain any numbers. --Pjacobi 13:56, July 30, 2005 (UTC)

My numbers are from the top of my head. And 50Hz and 10kV will be right I guess, as it is pretty standard. When I have time maybe I will look up some of them, as they easy to find in the web for a lot of FELs.

I don't doubt that your numbers are right, but which numbers have been wrong? The article didn't contain any numbers? --Pjacobi 15:22, July 31, 2005 (UTC)

Just seen your edit. Now I understand. But your contributions still read more like a forum posting, than an encyclopedia entry. You, me or someone else should tidy this up a bit. --Pjacobi 15:24, July 31, 2005 (UTC)

Thanks for your interest! I am German and I was never said to be a good writer and I have no ideas, but maybe if I regain interest in FELs I will try.

I linked the articles together, since this is my main point. I want to postpone the cascade arrangement inherent to magnetrons, FELs, and some TWT, until people understand the basics of a single amplifier.

Airfoil

I moved your recent additions to airfoil to foil (fluid mechanics), since I think the fit better there. The general discussion of lift producing bodies shouldn't (in my opinion at least) be in an article about foils that work in air, since all the information also applies to foils working in water or other fluids. I intend to do additional work to the foil article as time permits (including screenshots of XFoil pressure diagrams) but I'm only an amateur as far as fluid mechanics goes, and my knowledge is limited to low Re applications in sailboats. scot 14:12, 1 August 2005 (UTC)

thank you

Image:Antenna boom comparison.png

I thought your diagram comparing the various antenna types had great intuitive appeal. There were a few discrepancies that I noticed, however. The antenna you have labeled as a Beverage is actually a rhombic; the distinction between the two is significant. The antenna labeled 'periodic' is properly termed 'log-periodic' and its feedline is connected to the shortest elements, not the longest ones as you are showing. That connection does not work. I took the liberty of slightly cropping your image and creating a thumbnail of it on the Yagi Antenna page so that it would fit on smaller screens. Since you have the original, may I suggest that you pick up these corrections and re-upload the image? Thanks! Jim, K7JEB

Oops, make that: JEB 13:20, 23 August 2005 (UTC)

I will have to look up how do I send wiki messages. I am just learning about antennas. Thank you for your attention! :-)

'log-periodic'>> I did not find an easy way to draw the 'log' scaling of the elements at first, but now its done!

its feedline is connected to the shortest elements>> As in: http://www.radio-electronics.com/info/antennas/log_p/log_periodic.php I added a second flow image to contrast it against the others.

rhombic>> I added the link to the image

Beverage>> I will add it in the image. This weekend, probably.

Arne

    Good job, Arne....   Jim, K7JEB JEB 21:44, 26 August 2005 (UTC)

I keep looking at this diagram - but I don't understand it. I understand area rule. Maybe I'm just being dumb. I understand that there are 2 shock waves coming off - but everything else appears to be abstract - especially the area rule between the two dotted lines. Can you explain it better ?

I think a better illustration would be to have a F-104 style plane compared with a non supersonic plane (P-51 ?) with a graph of the comparing the cross-sectional area at each point along the length of the airframe. So that the P-51 would have sharp jarring changes on the graph - where are the F-104 would be smooth.

Megapixie 08:01, 6 October 2005 (UTC)

I added another picture, wich I think fit to your question:

In the beginning I was wondering why any plane has a sub-pressure shockwave. I took me a second look, to realize that no supersonic plane has such an extreme delta-wing-canard combination as to say the fuselage is in between the wings, not even the Eurofighter Typhoon.

And for <Mach2 I don't like the razor sharp edges of the F-104 anymore but guess a sweep is more appropriate.

I've put my money where my mouth is and produced a prototype of what I was talking about. I've totally made up the shape of the area curves.

Let me know what you think.

Megapixie 11:44, 10 October 2005 (UTC)

The picuture looks right to me. I thought the plane looks like this: http://en.wikipedia.org/wiki/F-104_Starfighter Anyhow I was mutivated by the fact that civil supersonic planes and old spy planes want to fly as high as possible: Sliding on the surface of the atmosphere. So I think a high altitude supersonic plane should look like a boat ;-) So I tried to draw an innovative shape as the planes of the past are already known and pictured to great detail. But you may be right, that series of picures of area curves throughout history is needed: Subsonic plane, Bell x-1, DeltaDart ,transsonic planes (Chessna Citation X, Boing 747, B-1 in low level flight, Boeing Dreamliner ) , Nasa blunt nose plane, Japanese concorde successor. --Arnero 15:09, 10 October 2005 (UTC)

I did some updates to the page. Mostly text to reduce bandwidth.--Arnero 19:19, 20 December 2005 (UTC)

SPIDER

The info on SPIDER has been moved to spectral interferometry for direct electric field reconstruction. If you know a lot about this, you might be one of the few at Wikipedia, so any expansion would be welcome. — Laura Scudder ☎ 21:42, 19 December 2005 (UTC)

My colleages have one, know some papers and I want to understand. I like interference and Frequency mixer. --Arnero 19:19, 20 December 2005 (UTC)

Arnero: A good place to start would be Ian Walmsley's web page (I linked it on the SPIDER page.). He has a list of publications there. I understand how SPIDER works, but I'm a FROG person. I'm afraid that I would just end up bashing SPIDER. -- Erik Zeek 19:30, 20 December 2005 (UTC) OK, I am happy that there is now an article about this theme, because I did not like the first spider explanaitions which came to my eye. Maybe you can start a bashing section in that article ;-) --Arnero 22:37, 20 December 2005 (UTC)

Arnero: You should add notation to the picture that you added to the SPIDER article. As it stands, it doesn't help much because there are no labels!Patrick Berry 18:54, 1 May 2006 (UTC)

Thin film polarizers

I think the comment about Brewster's angle in the context of thin film polarizers is at best confusing, and probably outright wrong. The response is mostly due to the variation in the interference in the film with angle of incidence rather than Brewster's angle. When you make a thin film polarizer, you aren't constrained to keep the angle at or even near Brewster's angle. Unlike Brewster's angle, the polarization can change dramatically with wavelength. Perhaps there are thin-film polarizers that do use an internal Brewster's angle reflection, but this certainly need not always be the case.--Srleffler 14:15, 30 December 2005 (UTC)

>variation in the interference in the film with angle of incidence
This does not distinguish between directions of polarization, only wavevector directions

>Perhaps there are thin-film polarizers that do use an internal Brewster's angle reflection, but this certainly need not always be the case
So why are you so certain?

>Unlike Brewster's angle, the polarization can change dramatically with wavelength
Yes thats a difference, but I think the only one. One usually uses thin film polarizers for narrow bandwidth lasers and there the compactness is of greater importance. --Arnero 16:07, 30 December 2005 (UTC)

Please don't put discussion or questions in the article pages. That kind of material belongs on the article's talk page.--Srleffler 13:47, 6 January 2006 (UTC)

Sorry.--Arnero 17:23, 6 January 2006 (UTC)

According to Macleod's book (see ref. below), a MacNeille prism works the way I think you have in mind, with a thin-film stack designed such that light passes through a series of thin-film interfaces at Brewster's angle. These polarizers have a very wide spectral range, but limited angular range for obvious reasons. Plate polarizers cannot be made based on this principle, because "the Brewster angle for normal thin-film materials...is found to be greater than 90° referred to air as the incident medium. In other words, it is beyond the critical angle for the materials. [In the MacNeille prism] this is solved by building the multilayer filter into a glass prism so that the light can be incident on the multilayer at an angle greater than critical."

Plate polarizers, on the other hand, depend on the fact that the width of the high-reflectance zone of a quarter-wave stack is different for s and p polarization. There thus exists a region at the edge of the reflection band where the reflection is high for s-polarized light and low for p-polarized light. Further layers are used to smooth out ripples in the transmission spectrum, etc. The spectral range for these polarizers is narrow, and shifts with angle of incidence like any other bandpass coating.

While cube polarizers can be made based on the Brewster principle, they are often made using the same principle as plate polarizers. The latter tend to have a broader spectral range than plate polarizers, because of the higher angle of incidence of the light at the coating layer interfaces.

• Macleod, H Angus (2001). Thin-Film Optical Filters, 3rd ed. Institute of Physics. pp. 362–368. ISBN 0750306882.

--Srleffler 14:42, 6 January 2006 (UTC)

>>greater than 90° referred

That should be easy to caluclate. I'll do that on sunday. Thank you. Sadly I cannot find the book in my bib

>>MacNeille prism

So it has more in common with the brewster polarizer than with the birefringece prisms and so the article should be sorted this way

>>high-reflectance zone

So it has not to be exactly the brewster angle, but surly the design started with brewster angle and than made a compromise. And this design might also use Air-Glas Brewster's angle.--Arnero 17:23, 6 January 2006 (UTC)

Texture mapping

Please make a point to grammar and spell check your contributions to the wikipedia. Canadacow 22:28, 8 January 2006 (UTC)

QFT

Recently, you wrote the following in the Quantum Field Theory article:

Only by accident electrons were not regarded as de Broglie waves and photons governed by geometrical optics were not the dominant theory when QFT was developed.

I don't believe this is correct nor is placed in the correct place. If I understand the history correctly, fields were routinely described by planar wave propagators early on. This turns out to be essential to the theory. Second, there doesn't appear to be a rigorous definition of "de Broglie wave". As far as I can tell, it's just matter that exhibits wavelike behavior, which would naturally be described by the above system.

Geometrical optics is based on ideas like Huygens' principle (propagation of light as wavefronts not as rays) which also show up in QFT through planar wave propagation. So IMHO, the fundamental ideas were present from the begining. Further, the scientists involved in construction of these theories were aware of the above ideas. So it's not clear to me that your assertions are correct. A citation (so that this observation would be confirmed by external sources) would be a good idea IMHO.

Finally, this sentence appears in a discussion of quantizing classical fields. It's a historical remark which at best is tangential to the modern subject. Perhaps this indicates a need to create an article on the history of QFT, but I don't think the sentence is appropriate where it is, and perhaps isn't appropriate for the QFT article at all since little in the way of historical information is described therein. The little history there is appears to be used specifically to develope the concepts behind modern QFT. In particular, there are probably a number of failed approaches and routes not taken here. What makes this particular route worthy of note in explaining modern QFT? -- KarlHallowell 08:04, 9 January 2006 (UTC)

So what does this sentence mean then?: There is no such thing as a wavefunction for a single photon in classical electromagnetisim, so a quantum field theory must be formulated right from the start.

--Arnero 12:37, 9 January 2006 (UTC)

I had to look through the section to see the context. You can quantitize a particle by make it's classical position and momentum coordinates into quantum observables. Here, there are a finite number of operators (usually some multiple of 4 or the other dimensions that appear regularly in these theories). A photon is described by a continuous field with four vector components in classical theory. So literally there are an infinite number of variables that you'd have to convert to quantum observables. I don't buy the claim that this is an uncountable number of variables since the set X mentioned in the section usually has a dense countable subset (every point is arbitrarily close to some point in the subset) and the classical fields are continuous so we could restrict our attention to the countable subset.

Even so that means at best a countably infinite number of position and momentum operators with complex relations between each other. Classical quantum mechanics is just too clumsy to compute this efficiently. Hence, the claim that QFT (implemented via the approach mentioned in the section) is "the way out". There probably are other ways to handle this, but QFT appears naturally in this problem. -- KarlHallowell 17:49, 9 January 2006 (UTC)

Thank you for your answer, but I got a bit lost. What I really wanted to ask (sorry for my unclear questions): Does the sentence "There is no such thing as a wavefunction for a single photon in classical electromagnetisim, so a quantum field theory must be formulated right from the start" infringe on Wave-particle_duality, which states that even before diving into the math of QFT, one has to treat a photon like a particle and a wave at the same time and should not favour any of them, like sexual equality. And isn't history such that great physicist always obeyed this law anticipating QFT and only small minded people wanted to think black and white and ignored that duality. Of course there is no wavefunction for a single photon, but there could have been a Newton's laws of motion. The sentence make it sound as if photons have to be treated differently from electrons ( Discrimination#Gender_Discriminatio ). But the real difference is the Bosonic and the Fermionic character. --Arnero 19:09, 9 January 2006 (UTC)

My understanding is that an electron, classically (here, it is being treated as a pure particle not a wave-particle) can be described by a simple set of parameters (say position and momentum coordinates). Each of these parameters must be quantized. Even at this stage, you will see the manifestation of wave-particle duality since that was one of the inspirations for quantum mechanics (not so for QFT, but they would have it in mind IMHO) in the first place. A photon is actually a propagating electromagnetic wave. In the article, they mention that classically the EM field is described at every point in space by a 4-dimensional vector (ie, it is a vector field). Each of these vectors at each of these points needs to be quantized under the old quantum mechanics approach. You also pick up a lot of dependencies since if two points are close to each other their fields tend to be close as well. So QFT appears more or less "naturally" as a means of handling this infinite number of quantized parameters with infinite dependencies. The wave-particle aspect appears pretty much as a corollary.

The difference here isn't in whether these things are treated as wave-particles (they both are) or even in the difference between boson and fermion. But rather that the electromagnetic field requires a single index in its description while an electron (though matrix valued, ie, spinor-valued) does not. This leads to a new parameter called spin which describes the number of indices and whether the field is a boson or fermion. If the field has nonnegative integer spin k, then it is a boson and requires k indices to describe it. Usually, bosons are mathematically described by real or complex tensors with k indices. Meanwhile, fermions are described by a spin of k+1/2, k again being a nonnegative integer. These fermions would require k indices. Usually, this is represented as a spinor-valued tensor with k indices. Finally, these theoretic results would have the photon being spin 1, and the electron being spin 1/2 (from an index counting argument), which experiment backs up.

In summary, any field with one or more indices is difficult to describe using regular quantum mechanics since you have to quantize a multi-index tensor parameter at each point in space, and thus have to deal with the problem of quantizing infinite parameters. -- KarlHallowell 15:02, 16 January 2006 (UTC)

I am just interested in table-top devices at low (harmless for humans) energy scale. So I am fine with cavity quantum dynamics, where the field inside the cavity is described by a fourier series. And I do not need the highest frequencies. I already only have a finite number of parameters before I start quantizing.

I hate the fact, that people tell me "the classical electron is a particle". Classical physics did not go far beyond sensation. No invisible small particles! A lot of layman do not believe you, when you tell them they are made off small balls. I think, I will not discuss this anymore.--Arnero 14:05, 17 January 2006 (UTC)

See also

Re: Mirror mount. The "See also" section in an article is special: it's supposed to be just a bulleted list of links to other wikipedia pages, possibly with a brief explanation of each. It's not supposed to be a paragraph. If something needs to be explained in paragraph form, it needs to be worked into the main text of the article and doesn't belong in the "see also" section. I renamed the section and cleaned it up a bit.--Srleffler 18:02, 21 January 2006 (UTC)

I should be a new article, but only afterwards I saw http://de.wikipedia.org/wiki/Hexapod (with nice image), I was strengthened to start a new article. But then I do not like the idea of 12 gimbal mounts to achive something which can be done with 6. And using kinematic mounts lets the legs rotate, possibly windung up the control cables. --Arnero 09:40, 28 January 2006 (UTC)

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Thank you, I added a copyright to this image. I somehow have problems finding my old images, where I might have missed the copyright tag. Since some time I always tag my images with PD-self, so the author should be clear.--Arnero 10:44, 1 April 2006 (UTC)

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Weird IPA pipelink

Could you please explain this edit? Is it some kind of joke? "Oh-jhay" is definitely not IPA. —Keenan Pepper 22:40, 27 March 2006 (UTC)

I wanted to complain about the previous version, but had no time to look up the right phonetics for Auger.--Arnero 10:47, 1 April 2006 (UTC)

Image:FET comparison.png

This image needs more in the way of labeling. Each column is a different type of transistor? That's not obvious from the picture. The terminals should be labeled, too, and using color alone to convey information is discouraged because of color blindness. — Omegatron 01:09, 31 March 2006 (UTC)

• labeling: This makes image files big and uninternational
• column: I should reorder the image
• color blindness: I am pretty sure that my colors can be distinguieshed, because they all have a different intensity. Red may look as black for color blind people, maybe I switch to orange.

--Arnero 10:53, 1 April 2006 (UTC)

1. Labeling: It needs labels. The image is not clear at all from the caption. Image use policy says to upload two versions of the image; one with labels and one without, so that the blank can be labeled in other languages. It's even better if you create diagrams in SVG. Then the labels are literal text that can be edited with any text editor to create international versions.
2. Color blindness: Labels would be better. Some people can't see any color at all, and many are viewing the articles on black and white printouts, old monitors, PDAs, cell phones, etc. — Omegatron 20:08, 1 May 2006 (UTC)

Because of induction of the windings, power requirements, and temperature management some glue circuitry is necessary between digital controller and motor. Somehow wiki renders it different then inkscape :-((

--Arnero 11:04, 6 May 2006 (UTC)

TEA laser

When the license states PD-self, shouldn't the source be clear?--Arnero 06:43, 2 April 2006 (UTC)

Yes, and normally, OrphanBot correctly spots a {{PD-self}} and {{no source}} double-tagging. What happened with those images is that there was a {{no source}} tag on the English Wikipedia image description page, and a {{PD-self}} tag on the Commons page, while the image itself was on Commons. OrphanBot doesn't deal with Commons, so it only saw the {{no source}} tag. --Carnildo 08:11, 2 April 2006 (UTC)

Wave-particle duality

You wrote the Wave-particle duality in your user page in other form. Have you found yet that it exists? (I don't need answer.)-- Harp 15:28, 5 April 2006 (UTC)

I found out, the Quantum Field Theory article says it best, but I am still wondering about this:

The bosonic field operators obey the commutation relation

$\left[\phi (\mathbf {r} ),\phi (\mathbf {r'} )\right]=0\quad ,\quad \left[\phi ^{\dagger }(\mathbf {r} ),\phi ^{\dagger }(\mathbf {r'} )\right]=0\quad ,\quad \left[\phi (\mathbf {r} ),\phi ^{\dagger }(\mathbf {r'} )\right]=\delta ^{3}(\mathbf {r} -\mathbf {r'} )$

where $\delta (x)$ stands for the Dirac delta function. As before, the fermionic relations are the same, with the commutators replaced by anticommutators.

I would be happy about any comment about this, because this formulation is in real space and real time and not obscured by fourier transformation or path integral formulation. --Arnero 11:33, 14 April 2006 (UTC)

Area rule again

I was the primary author of the area rule article, and like Megapixe, I'm also trying to figure out what your diagram in the article means. For the life of me, I can't understand what it is supposed to represent. I can't even figure out what direction we're looking at it from, is that a side view or a top view? Nor is it at all clear how this diagram relates to boom reduction. Further, I don't see what sonic boom reduction has to do with the area rule at all. After all, your own lable seems to suggest the "break" the rule deliberately.

Would you be upset if I simply moved all of this to the sonic boom article? It seems much more on-topic there.

Maury 12:17, 23 May 2006 (UTC)

From the top of my head (I did look at the article for some time):

I can't even figure out what direction we're looking at it from, is that a side view or a top view?

I guess I showed a top and a side view, to show how the diameter in one view is traded for the other

Nor is it at all clear how this diagram relates to boom reduction.

The area rule prime purpose is to reduce the sonic boom. Indirectly the drag and the annoyance on the ground are reduced.

Would you be upset if I simply moved all of this to the sonic boom article? It seems much more on-topic there.

No I am not upset.

Some new stuff: I read that jet engines emit a lot of noise out of their inlet / outlet. In case of supersonic fligth this noise travels within the sonic beam. Therefore inlet and outlet have to be above the wings, so that the noise is sent into space. One of my images is as side view, showing the inlet on top of the airplane. Maybe I also drawed an image showing the outlet on the top. --Arnero 09:49, 25 May 2006 (UTC)

Update, after I looked at the image again:

After all, your own lable seems to suggest the "break" the rule deliberately.

Since every airplane starts from zero area at the tip and ends at zero area in the end, one has to break the rule. But one does this at the front of the airplane and in the end, and not in the middle. But most subsonic airplanes change area near the middle, because of their wings. Usually one part of the fuselage is put in front of the wings one after the wings. A conus on the fuselage is used to prevent excessive shock waves. I draw the picture the other way round ( not really original research, many concepts point in this direction). One wing in front of the fuselage and one behind. Wings can have razor sharp edges to establish the area with out creating shock waves. Because these razor are very wide a lot of area can be established without big shocks.

Off topic: The easiest way to reduce the boom is to fly high. For this lift is needed. Lift leads to shocks. I do not want to waste shocks. So all the shocks should be used for lift. Therefore overpressure shock should point downwards. And the underpressure shock should point upwards. --Arnero 12:23, 25 May 2006 (UTC)

WP:NOT

I reverted your edit to Fresnel equations, on the basis of WP:NOT#Wikipedia is not an indiscriminate collection of information, item #4. "How-to" type information doesn't belong in Wikipedia. Wikipedia is an encyclopedia, not a textbook or instruction manual. Source code is not appropriate, even if it is useful and relevant to the article topic.--Srleffler 00:07, 16 October 2006 (UTC)

But it was soooo short :-( Arnero 15:58, 16 October 2006 (UTC)

Inlet cone

I noticed your current edits here.

I'm not sure that they are necessarily accurate. I found out that the SR-71's cone retracts as the vehicle accelerates (although I'm not entirely sure why, but that's what the SR-71's manual and the article says).WolfKeeper 14:53, 14 October 2006 (UTC)

Oh, that is strange. Maybe the cone is plugged from the outside into the cowl? Arnero 17:46, 16 October 2006 (UTC)

you might want to modify your edit to Digital-to-analog converter

the context of that discussion is in Delta-Sigma (that is oversampling and noise-shaping) DACs and these high-resolution audio DACs do not run at terra-hertz. (answer here, i'll watch your talkpage.)r b-j 15:34, 13 November 2006 (UTC)

Answer first, modify within one week. This time it fits into my discussion, rather than into that of the article, because "my contributions" show, that I edited Gramophone_record and needed a clear estimate on the quality of CD-sound. Using the DVD-format, the DVD is better, using an 1-bit DAC I have the feeling that the Gramophone_record is better. The noise shaping article does not compare Gramophone_records with 1-bit DAC, but

mentions Absolute_threshold_of_hearing, so it has some argument. Another one would be that quatization error is reciprocal to frequency. No Gramophone_record-fan will belive me that DVD-audio is better, when I tell them I use noise shaping to the 100th order. And for technical applications I say a 1-bit DACs is as good as pulse-width modulation with the same clock (width measured in clock ticks), but does not need the antialiasing filter. Arnero 20:44, 14 November 2006 (UTC)

sorry Arnero, i dunno what it is of you speak. that quadruple the sampling frequency for each bit rule is not applicable in the case of noise-shaped oversampling. usually the sampling frequency is about 3 or 6 MHz to get 18 to 24 bits (depending how resolution is defined) of resolution with a 1-bit converter. it's not an issue of threshold of hearing or of Fletcher-Munson curves or anything like that. it's that when noise shaping is not applied there is more noise error in the baseband (up to approx. 20 kHz) than it is when noise-shaping is applied. r b-j 23:00, 14 November 2006 (UTC)

Then please improve the Noise shaping article! More sources, some images, no suggestions, I haven read it thoroghly. Before this article is not easy to understand, I think worst case should be assumed for 1-bit DAC. And I say: double frequency for each bit. Arnero 08:35, 15 November 2006 (UTC)

And by the way, the 1-bit sequence is fully defined by the 1-bit ADC. Maybe I am blind, but I see no noise shaping possiblities there. Arnero 11:42, 15 November 2006 (UTC)

reverted edit

I've reverted this edit, mostly for the language. You've got to find a better way to express whatever it is you want to say, because calling text in the article "bullshit" is not it. If there's a dispute, please take it to the talk page. Thanks.--Kchase T 08:12, 12 December 2006 (UTC)

I think there is no dispute. Someone wanted to say, why class-E is only used for RF. I think he guessed wrong.Arnero 14:54, 12 December 2006 (UTC)

Swimming tables

I find absolutely trivial and unencylopedical the table you added to Breaststroke, so I deleted it. Bye and good work. --Attilios 00:13, 10 February 2007 (UTC)

But you know that the article is bad und needs links ? Arnero 13:26, 13 February 2007 (UTC)

Avalanche transistor

Hello. I tried to answer to your questions about my edits of the avalanche transistor voice: you could find my answers on its talk page.Daniele.tampieri 20:32, 17 February 2007 (UTC)

Chirped-pulse amplification

Could you comment on this edit? I don't see it. Whether or not the gain medium is depleted depends on the pulse energy, not the pulse duration. Or am I overlooking something? Han-Kwang 23:36, 22 March 2007 (UTC)

Thank you for your message, because I do not watch the discussion of the article. I will answere there, because I think this is only interesting for this single article. Arnero 16:26, 23 March 2007 (UTC)

Bipropellant rocket

I reverted your edit about pintle injectors. The edit didn't read very well where it was, and further there was a mistake in the final sentence, to the extent that I was completely unclear what you were really saying. If you wanted to re-add the information again, it might be a better idea to have a separate section on injector types or something.WolfKeeper 22:48, 13 April 2007 (UTC)

Transformer

Hi, do you mind if I do something with this edit? It's not well-placed, you see, slipped in between two headings, and it's mostly repeating things that are written further down in the article. — BillC ^talk 10:48, 13 May 2007 (UTC)

Thank you for your attention. My answer got longer, so I put it on the discussion page of the article Arnero 19:42, 13 May 2007 (UTC)

Welcome to Wikipedia. We invite everyone to contribute constructively to our encyclopedia. However, talk pages are meant to be a record of a discussion; deleting or editing legitimate comments, as you did at Talk:Wireless LAN, is considered bad practice, even if you meant well. Take a look at the welcome page to learn more about contributing to this encyclopedia. Thank you. Oli Filth 07:30, 13 July 2007 (UTC)

UUps sorry, somehow copy and paste went wrong. Thank you for correcting my mistake. Now I will also start discussions-texts in an editor and then paste them, so that I do not try to mark anything. Arnero 09:21, 15 July 2007 (UTC)

Molecular vibration

I am the expert who wrote most of this article. I don't understand your problem with irreducible representations. In the context of molecular vibrations these are found in character tables. A character is the trace of the matrix so your reference to matrices is misplaced. An irreducible representation is defined by a set of characters, one for each symmetry operation, but operations with the same character are listed in a single column of the character table. I shall revert your edit unless you object. Please respond by e-mail. You can get my address at [2]Petergans 09:32, 1 September 2007 (UTC)

reverted. I guess I did read too often stuff like: "exciton states having predominantly T2g , T1g , Gg , and Hg total symmetries" Arnero 08:53, 2 September 2007 (UTC)

Image:O-ring.svg

Hi Arnero, Do you have a reference for this illustration? I'm a little worried that it doesn't reflect common mounting of O-rings. See the gland details in the illustration above yours to see what I mean. Thanks. --Duk 19:12, 3 October 2007 (UTC)

round holder, but no round sealed surface

general description about a seal with softer material

OK no reference. But maybe you could write (in the discussion of the article), why the other seal is impossible. Arnero 18:20, 4 October 2007 (UTC)

I'm not saying your illustration is right or wrong, just uncommon (I've never seen that type of mounting used). There are certainly many different ways to mount o-rings. Here are some references that describe common o-ring mountings:

• O-ring specifications, some important considerations, from Hydraulics and Pneumatics magazine
• Parker O-ring handbook, from Parker Hannifin
• gland design, from oringsusa.com
• different mounting details
• oring FEA.

I'm just concerned that your image shows a very uncommon mounting and is therefore potentially misleading. How did you come up with the pressure distribution? --Duk 19:19, 4 October 2007 (UTC)

Come to think of it, back-up rings provide a mounting that is similar, but not the same, as your illustration [3], [4]. Was that what you were trying to show in the illustration? I have to admit, I'm intrigued - was your illustration based on a design you've seen? --Duk 19:40, 4 October 2007 (UTC)

I may have seen it in a construction of a colleague. Original research: Squeezed to dead O-rings. I mostly use conflat flanges for our ultra high vacuum applications, but sometimes have to use O-rings. I want them to be as airtight as possible. I will follow your links later. Arnero 21:03, 4 October 2007 (UTC)

http://www.parker.com/o-ring/Literature/ORD5700.pdf

page69: static and vacuum fills the whole void

stresses

http://www.dhcae.com/FEA.htm: Rolling simulation

http://www.glossary.oilfield.slb.com/DisplayImage.cfm?ID=479

Some sites I found regarding back-up rings sort of in vacuum applications

http://n-c.com/Page.asp?NavID=397

http://www.mdc-vacuum.com/urd/uniface.urd/ecf0070w.display

I will remove the image Arnero 19:34, 5 October 2007 (UTC)

---

O-ring mounting for an ultra high vacuum application

I put your image back into the article along with the reference. Cheers! --Duk 21:35, 5 October 2007 (UTC)

Oscilloscope

Arnero, in the Oscilloscope article, on 15 December 2006, you say

Because the electrons have already been accelerated by hundreds of volt, this amplifier also has to deliver almost hundred volts, and this with a very high bandwidth.

This does not makes perfect sense in English. As I do not know the answer, I do not know how to correct it. The simplest change that would make it a sensible statement in English is, perhaps:

Original

Because the electrons have already been accelerated by hundreds of volt, this amplifier also has to deliver almost hundred volts, and this with a very high bandwidth.

Edited

Because the electrons have already been accelerated by hundreds of volts, this amplifier also has to deliver almost one hundred volts, and this with a very high bandwidth.

Also, we were taught in school not to begin a sentence with 'because'. A simple replacement for that would be 'since' as in:

Original

Because the electrons have already been accelerated by hundreds of volt, this amplifier also has to deliver almost hundred volts, and this with a very high bandwidth.

Edited

Since the electrons have already been accelerated by hundreds of volts, this amplifier also has to deliver almost one hundred volts, and this with a very high bandwidth.

Finally, I'm assuming that 100V doesn't meet your criteria, and so the better edit would read along the lines of:

Original

Because the electrons have already been accelerated by hundreds of volt, this amplifier also has to deliver almost hundred volts, and this with a very high bandwidth.

Edited

Since the electrons have already been accelerated by hundreds of volts, this amplifier also has to deliver almost eight hundred volts, and this with a very high bandwidth.

(I took a guess at the 800V figure, I have no idea if this is in the correct range). The emphasis on word groups (above) is mine and is not intended to be copied into the Oscilloscope article; it is there to highlight the changes I'm suggesting.

Tetonca (talk) 19:02, 10 December 2007 (UTC)

Your proposals seem reasonable. Sadly I am no native speaker. I wrote this under the influence of working with signal electronics in the lab. The typical fast transistor electronics likes signals in the 1 Volt range, while the inputs of an analog oscilloscope have a limit of 400 Volts.

400 Volts at vertical plates

Arnero (talk) 22:49, 14 December 2007 (UTC)

Thermal Efficiency

I undid your revision of the thermal efficiency article due to grammer and the material added being confused and out of place. I'm not sure the Carnot limit applies to Solar cells like you state (do you have any references?) and the bit about detonations just seemed odd to me. I don't think higher temperatures around shockwaves do allow higher efficiencies and while there are large temperature gradients within engines it doesn't seem relavent to the article to me. Andrew.Ainsworth (talk) 13:27, 13 January 2008 (UTC)

OK, I personally provided not enough references and wiki links and am no native speaker. Anything else: Discussion page of that article Arnero (talk) 17:51, 16 January 2008 (UTC)

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TEA Laser

Arnero, I have looked at your edits on the TEA laser page and they just will not do. I understand and commend your enthusiasm, but much of what you have put on the page relates specifically to nitrogen lasers, rather than generic TEA lasers. I think that if they must be included, those links should be on the Nitrogen Laser page with one link from the TEA laser page. In addition, and please forgive me for mentioning it, there are mistakes in your English. The TEA Laser article is in the English Language Wikipedia, so the standard of English must be acceptable. The difficulty with some of what you have written is not just that the syntax is incorrect, but that because of that, the meaning is unclear. I hesitate to mention this, but in science accuracy and clarity is essential.

Clarity is essential, I agree. Most of the sources do not offer clarity, therefore it is long way before the text gets readable.

A major problem exists in your insistance in regarding nitrogen lasers as "TEA" lasers, when they differ from CO2 and Excimers in so many ways. Nitrogen Lasers require no separate preionisation and the pulsed energies involved are much smaller. I really believe that they are not "TEA" lasers in the accepted sense of the word.

Of course they need preionisation to run with any efficiency. If you look into some of the sources you would see that excimer lasers

can become nitrogen lasers by just using nitrogen.

I have no intention of getting involved in an "edit war" with you, but I would ask you to consider what I have said. You can leave a message on my talk page, or email me at wikimaggs@gmail.com. Peter Maggs (talk) 12:17, 5 May 2008 (UTC)

I was hoping for a fruitful discussion and I do not want to overload the articles dealing with the individual laser gain media with

preionization and driver issues. Besides discharge is discharge and this separatism of spark gap discharge, thyratron discharge, preionisation discharge, main discharge just keeps people dumb. Arnero (talk) 18:39, 5 May 2008 (UTC)

Image:Piston engine breathing.svg

Arnero, this bizarre drawing has nothing to do with the subject of any of the many articles you posted it in, and even if it did, it certainly doesn't belong in the see also section. Basically you spammed a random, spurious image across multiple articles, apparently because you're so proud of having created the drawing that you want it to be on Wikipedia in as many articles as possible. We don't do that here. This what you did falls somewhere in the range between vandalism and article ownership, neither of which is allowed. I found it extremely difficult to assume good faith on your part, but I managed to scrape up enough faith not to tag the removals of your image as vandalism cleanup...this time. —Scheinwerfermann (talk) 02:21, 7 July 2008 (UTC)

So why is this piston engine subject so broken up across multiple articles? Where are those restrictions to the air flow everybody wants to avoid? You may notice that I usually do not spam across multiple articles, so it must have been for a reason. You write a good article, then I do not have to be proud of anything. Arnero (talk) 16:20, 11 July 2008 (UTC)

You may like to comment here. Cuddlyable3 (talk) 12:32, 12 July 2008 (UTC)

Revert (Fresnel equations)

I reverted this edit. The equations were correct. (I checked against the original source.) Be careful: there are several different formalisms that are used for treating the Fresnel equations. Relations that work in one formalism do not work in others. In this case, the irradiance is computed in the plane of the boundary, so indeed energy is conserved by T + R = 1. The projection of the wavefront on the boundary is already included in the coefficients.--Srleffler (talk) 04:13, 13 September 2008 (UTC)

Thanks for the direct pointer to that book. I may have a look. Until then I do not understand why someone would define the intensity of the light with dependence on an arbitrary surface the light shines on. That is so contrary to anything I've read which deals with lasers. The article that deals with intensity allows for both definitions, but we should state which one Hecht uses in that context. What about the current version of the article? Arnero (talk) 20:44, 15 September 2008 (UTC)

I changed the article. These coefficients are convenient because they can be thought of as coefficients for power, rather than intensity. This is convenient for a lot of practical applications, where one does not particularly care about the local intensity of the reflected and transmitted beams, but rather wants to know what fraction of the incident power is reflected. Hecht indeed describes these in those terms. I've seen other treatments that talk instead about the component of the poynting vectors perpendicular to the interface, which amounts to the same thing.--Srleffler (talk) 00:03, 16 September 2008 (UTC)

I've looked into the book and it is self-consistent, but the extract in the article has some dangling bonds. I do not think that power is the right solution. Arnero (talk) 17:57, 17 September 2008 (UTC)

Ok, too fast an answer, power is ok. Arnero (talk) 18:17, 17 September 2008 (UTC)

Image caption needed on

I saw that you added this image to the Suspension article, but it seems to be lacking context and captions. Could you please add captions to the various types of suspension you depicted in the image (preferably, both to the image box in the Suspension (vehicle) article and the Commons image description...)?

Thanks! Georgewilliamherbert (talk) 05:56, 18 July 2009 (UTC)

I second that. It's too difficult to deduce meanings solely from the article. saimhe (talk) 06:08, 13 October 2009 (UTC)

The image was a quick shot. Now after reading more about suspensions and letting the knowledge settle, I still like the image, but added a caption hinting on its limitations. Arnero (talk) 20:57, 29 October 2009 (UTC)

translation of Hermann Föttinger art.

we could use a translation of Hermann Föttinger in german wiki.Wdl1961 (talk) 20:03, 10 February 2010 (UTC)

Colorblind?

This is meant purely as a potentially informative rather than accusatory message, but I wonder if you might have some form of colorblindness? The reason I say this is that in this [5] edit you identify the outer lines as red when they are actually orange. I've heard of a number of instances where a person with color-blindness wasn't aware that was the case, so assuming that edit wasn't simply a mistake perhaps this message might be helpful. Imyourfoot (talk) 06:25, 12 March 2011 (UTC)

Ah, sorry, I may have changed my mind to get a shorter caption, and then did not find the time to change the SVG. Arnero (talk) 18:40, 17 December 2019 (UTC)

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Re: Why LZW for GIF?

I read your talk comment on the GIF page about using LZW. I don't know the reason why Compuserve used LZW for compression, it was probably a current method in 1987 which worked well with the machines at the time. Some newer formats use other approaches like PNG or TIFF, but the GIF format is probably as-is for historic compatibility. AlexLehm (talk) 13:58, 27 June 2019 (UTC)

yes. LZW is small and fast. Low risk. Arnero (talk) 18:42, 17 December 2019 (UTC)