6,975 reputation
1524
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 2 years, 11 months
seen 5 hours 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.


Jun
2
comment Are there any substances that allow sound to travel better then air?
+ Air isn't so bad either, at low frequencies.
Jun
2
comment Quick question on parallax and parsec
There is a background of relatively fixed stars. You see a pair of stars 3" apart. Six months later they are still 3" apart, but the pair of them together appear to have moved 1" against the background. The movement against the background is the parallax.
Jun
1
answered Does the lift created by a wing change when the slats are deployed?
May
30
comment Does the lift created by a wing change when the slats are deployed?
What slats and flaps do is increase the effective camber, or curve angle of the wing. Then the definition of AoA gets a bit fuzzy. What is a chord line that everyone could agree on?
May
30
comment Why do clouds fly?
@user2820052: NP. The air has a temperature, which is just the air molecules moving around excitedly, bumping into themselves and everything else. That bumping is what pressure is. If you're teeny-tiny and weigh nothing (or practically nothing) you will just bump around in the general chaos. Now, take a cubic liter of water - it has 100 square cm area on a side, and weighs 1kg. Now take a cubic cc of water, it has 1 square cm area on a side, and weighs 1 gram. 100 times less area, 1000 times less weight. Keep going. That's why dust motes fly and mountains don't.
May
29
comment Why do clouds fly?
@user2820052: forget the density and temperature. What matters is the ratio of volume to area. If a droplet has a diameter of 10^-4 cm, then its ratio of volume to surface area is 10^-4 that of a cc of water. In other words, its weight becomes insignificant compared to its area, so gravity has no more effect on it than a hair on your head.
May
28
comment Why do clouds fly?
@user2820052: If you were your present size, but you only weighed 1 gram, and if air molecules kept bumping into you like bouncing bowling balls on all sides, you'd fly too. And if there was a region of fewer bowling balls up ahead, it would attract many of them, and you'd be carried along.
May
27
awarded  Enlightened
May
27
awarded  Nice Answer
May
27
answered Is darkness really light?
May
26
comment Why do turbine engines work?
@Nathaniel: The torque exerted by the exhaust on the turbine is equal to the torque exerted by the compressor on the incoming air and, a little bit, on the pressure in the combustion chamber. (The vane area at the last stage of the compressor is small compared to the vane area of the turbine.)
May
25
comment Why do turbine engines work?
@Nathaniel: What do you mean "push more"?
May
25
revised Why do turbine engines work?
added 298 characters in body
May
25
answered Why do turbine engines work?
May
17
answered Why does light travel in straight paths?
May
17
comment Double slit experiment and single particles. Is the wave function just a mathematical model?
@Overloaded_Operator: It's not that photons don't have location, it's that they have a very specific definite location in every different world they are in. Are there actually many worlds - who knows? but nature seems to behave as if there are. Einstein objected to nature being probabilistic (I'm sure you know), so you're in good company. But that's where we are.
May
17
answered Double slit experiment and single particles. Is the wave function just a mathematical model?
May
16
comment What was the Law of Gravity better explained by?
@JFA: Sure. They're lengthy, and by rights, you should work the math along with him, pausing as necessary. I get too many interruptions, myself. But nobody can make it clearer than he does.
May
16
comment What was the Law of Gravity better explained by?
You need patience to understand this stuff, but Lenny Susskind's lectures can't be beat!
May
13
comment Fluid mechanics of aircraft at 10000 m
Usually we try not to make answers so complete that the OP can turn them in as if he himself did the work. That would short-circuit the education process. Whether you've done that here, I'm not sure.