8,097 reputation
1728
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 3 years, 7 months
seen 1 hour ago

BS Mechanical Engr.
PhD CS(AI)
CS Prof (4yr)
Numerous consulting jobs.
15 yr at http://www.pharsight.com
Published book on CS & several articles
4 kids, 2 grand
Pilot(student)

P.S. The picture is a Beta-prime distribution. It shows the program speedup factors you can get if you see a problem twice in 2, 3, 4, and 5 samples.


Apr
8
revised Can universe or anything be simulated with absolute accuracy?
added 47 characters in body
Apr
8
comment Can universe or anything be simulated with absolute accuracy?
@LifeH2O: That's a problematic hypothetical.
Apr
8
revised Can universe or anything be simulated with absolute accuracy?
added 47 characters in body
Apr
8
answered Can universe or anything be simulated with absolute accuracy?
Apr
7
comment The velocity of air on an airfoil
The best site I know on how wings work.
Apr
6
answered How does vasoconstriction/vasodilation of arterioles change blood pressure?
Apr
5
answered Is it possible for an inductor to have a voltage across it without any current passing through it?
Apr
4
answered Explain an experiment: airstream between two hinged curved surfaces
Apr
1
comment Roughness of the Surface and the time that a toy hovercraft hovers?
When you say "hovercraft" you mean something that floats on a cushion of air within millimeters of the floor or whatever it is hovering on, right? Then it all depends on the seal around the edges. The more air that gets out, the more power it takes to refill the air cushion, so the shorter the battery life.
Apr
1
comment Does a force being applied in an ideal case to an object of infinite mass where there is no friction always result in an acceleration?
$F=ma$ so $m=F/a$. You can talk about infinities and zero-divide if you like. Seems a little silly.
Mar
30
comment Since Earth spins, would an aircraft travelling opposite to direction of Earth spin take less time?
When I hear "why or why not" my homework-detector goes off. Regardless, if you can fly above the atmosphere and fly west toward that point, you will get to it sooner because it is moving east. Of course, if it's on the equator, you could simply get above the atmosphere and wait 12 hours, and it will come to you (though that means you are traveling west with respect to the earth at about 1000 mph). Anyway, if you're flying in air, which is basically attached to the earth, the spin of the earth makes no difference. It's just a matter of wind.
Mar
26
comment Is Magnus effect a corollary of Bernoulli principle?
It's not energy conservation along a streamline. It's momentum conservation along a streamline. It's $F=ma$, which is momentum conservation.
Mar
26
comment Why does a propeller suck in air from the front?
I bet your question comes from the standard wrong explanation of how wings work, the explanation that fails to account for downwash. Let me direct you to my favorite site for explaining how wings work.
Mar
21
comment How can a petrol car require less fuel at 55mph than a lower speed at the same rpm?
Just drive the car in first gear for an hour, it doesn't need much gas, but it doesn't go many miles either, so the miles per gallon is low
Mar
19
comment Is Physics being formally documented somewhere?
Actually, if there were a centralized database of physics knowledge of "immutable concepts", it would be a great resource for me and others who like to show where some such concepts are wrong :)
Mar
19
revised Coriolis force on bullet vs airplane
added 655 characters in body
Mar
18
revised Coriolis force on bullet vs airplane
deleted 372 characters in body
Mar
18
answered Coriolis force on bullet vs airplane
Mar
18
comment How much power can support an object to float in the air near the surface of the earth?
Go with @akhmeteli answer.
Mar
18
comment How much power can support an object to float in the air near the surface of the earth?
How near the surface? If the surface is really flat, like a polished granite table, and if the weight rests on a plenum of wide area, with a 1-micron gap around the edge, then it will take very little energy. The only energy it would need is to keep up some pressure to replace the bit of air that escapes.