# Search results

1. ### Next big thing in the aviation iddustry

I don't think so - not in the civil aviation, at least. Too many risks involved with malfunctioning of said devices.
2. ### Speed of pneumatic motor

Hi, here I am again. :) I was overwhelmed with work in the last few days, so couldn't reply. Yes, now I do understand what you intend. And your analysis is correct. If we put the pressure loss due to friction in the equations then - everything else being equal (piping, pressure difference...
3. ### Speed of pneumatic motor

Well, no... dm/dt and R are independent values. The mass flow of a gas (dm/dt) is decided by you. For example, you can control it with a ball valve, which can be set more or less open. R is a physical property of the gas used, and you have no control over it (if not by choosing another gas).
4. ### Speed of pneumatic motor

Not really. :) Let's carry on from the second equation: dm/dt = f * rho * V0 where: dm/dt = mass flow of the gas V0 = motor displacement f = frequency of rotation rho = gas density (0.176 kg/m3 helium; 1.225 kg/m3 air) If you want to see the pressure in this relationship, the easiest way is to...
5. ### Next big thing in the aviation iddustry

Remotely controlled unmanned flights with neurobiofeedback to the ground-based human pilot.
6. ### Simplify to find theta, my brain is fuzzled from to much work today

It's a simple quadratic equation a*x^2 + b*x + c = 0 , where x = e^theta. You can do it, don't give up. ;)
7. ### Tides in sea

Check this: http://oceanservice.noaa.gov/education/kits/tides/tides02_cause.html
8. ### Fluid dynamics question

That is correct. You can find a very good and easy-to-read short essay about Kolmogorov theory here (PowerPoint file): http://www.bakker.org/dartmouth06/engs150/09-kolm.ppt
9. ### Fluid dynamics question

As said above, Kolmogorov theory deals with turbulent flows at "sufficiently" high Reynolds numbers, whilst N-S equations can give either laminar-flow solutions or turbulent-flow solutions, depending on initial and boundary conditions. Think of a free uniform rectilinear flow, for example. If...
10. ### LaTeX Testing new latex processor

Hello, I have a problem... I can't see the "Sigma" icon for creating LaTex code, even in advanced text mode... I've tried both IE and Chrome, but still no icon there. What am I doing wrong?
11. ### Maxiumum Incident power on solar cell ?

1000 w/m2 is the standard value of irradiation, used for certification and comparison of PV cells - which is the case here, if I understood it well. For example, see this tech sheet of a Sharp 167 W module: http://www.abcsolar.com/pdf/sharp167.pdf - the bottom of the page 2, where it reads...
12. ### Speed of pneumatic motor

It can be explained in simple terms, imho, by considering a general equation: m = rho * V A time-derivative of this equation yields: dm/dt = rho * dV/dT or (since dV/dT = f * V0) dm/dt = f * rho * V0 where: dm/dt = mass flow of the gas V0 = motor displacement f = frequency of rotation...

:wink:
14. ### Maxiumum Incident power on solar cell ?

The power of sunlight at the ground level, when all the (mean) atmospheric dissipations and reflections have been detracted, is very close to 1000 W/m2 (outside the atmosphere it's value is 1367 W/m2 at the mean distance Sun-Earth). 1000 W/m2 is also the standard reference value used for...
15. ### Would anything exist if mankind - the observer/participator - wasn't around to see

All in all, I cannot demonstrate my point of view, and you cannot do it with yours. And we could go on with this for the next couple of years, I think (btw: yes - I think therefore I observe, scupydog). I agree with scupydog, this pub is closing and maybe it's time to go home. Anyone for a...
16. ### Would anything exist if mankind - the observer/participator - wasn't around to see

I think we should go back to the original question, the one in the title. The only possible and demonstrable answer to that question is, IMHO, that we don't really know and will never be able to know. A universe without observers is possible only as a thought experiment. And even so it is a...
17. ### Would anything exist if mankind - the observer/participator - wasn't around to see

Scupydog, if you don't elaborate on that phrase a little bit more, how can I get what's up on your mind? o:)
18. ### Would anything exist if mankind - the observer/participator - wasn't around to see

I have to admit that I don't get what you mean... Can you elaborate on this one?
19. ### Would anything exist if mankind - the observer/participator - wasn't around to see

You are right. I have not read your statement after the asterisk in the correct way and so the phrase "And finaly, that is what I meant" is not correct. The interpretation by which the things "do not exist unless we understand it to" doesn't rappresent my thoughts and it should be quite clear by...
20. ### Would anything exist if mankind - the observer/participator - wasn't around to see

I hate to quote myself, but I realize that maybe you guys have lost the final point of my reasoning, so I have to do it:
21. ### Would anything exist if mankind - the observer/participator - wasn't around to see

You have just performed a following thought experiment: - You have assumed the existance of the apple, and the photon hitting it. - That allowed you to imply that the information about the existance of the apple is carried by the photon. So now you have: 1) If there is an existing...
22. ### Would anything exist if mankind - the observer/participator - wasn't around to see

I disagree, almost completely. 1) A concept of the "information" is (IMHO) meaningful only in presence of an intelligent observer which can give a significance to it, which can encode the "input" (or "signal") to the "information". 2) In this particular case we have an observer, so there is a...
23. ### Would anything exist if mankind - the observer/participator - wasn't around to see

You have stuck to that argument and don't want to admit (or recognise) that it is flawed. I invite you to re-read our whole discussion and sleep on it a little bit. And while sleeping, try to think about this: what is that makes an apple what it is (i.e. an apple)?
24. ### Would anything exist if mankind - the observer/participator - wasn't around to see

The flaw in your demonstration lies in the fact that you are putting yourself in a privileged position, where you know what happened before that photon hit observer's retina. The observer doesn't know what happened, he only has the information carried by that photon. Based on that single...
25. ### Would anything exist if mankind - the observer/participator - wasn't around to see

And is there a proof that it did exist before we observed it? Please note that I've never said that things don't exist if we are not watching them. What I've said is that we have no proof of their existance if we are not able to observe them. Your affirmation quoted above is demonstrating...
26. ### Would anything exist if mankind - the observer/participator - wasn't around to see

Since observed, but not before observed. Before observing it, we have no proof of it's existance. After we have observed it we create our logical models (which need to be proved, and that's where Godel jumps in and spoils everything) which can tell us whether it will exist after we cease our...
27. ### Would anything exist if mankind - the observer/participator - wasn't around to see

Based on what evidence?
28. ### Would anything exist if mankind - the observer/participator - wasn't around to see

Sorry, I was absent from the forum for some time. The pleasure is mine, though I'm actually not italian. :smile:
29. ### Would anything exist if mankind - the observer/participator - wasn't around to see

How about "we WILL never know the real truth?" :wink:
30. ### Would anything exist if mankind - the observer/participator - wasn't around to see

That sounds like Gödel's Incompleteness Theorem extended to the whole universe... :biggrin: