6,271 reputation
1322
bio website en.wikipedia.org/wiki/…
location United States
age 69
visits member for 2 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.


2d
comment What is a linear probability density function?
@gj255: What you would do is take your sample of n velocities and sort them to get an empirical distribution. Then see which $av+b$ line fits it best.
2d
comment Duration of Satellite orbit in the shadow of the Earth
In the past, I've been guilty of giving complete answers to homework questions, rather than nudging the OP in the direction of figuring it out.
Apr
12
comment Why Don't Birds Stall?
Stalling is an effective way to dissipate excess energy. (That's why cars have brakes.) Small airplanes stall when they land. I suppose birds do too.
Apr
11
comment How much weight is lifted from each side?
None of the heights matter. What does matter is how the weight is distributed. Is the weight more toward the front, or more toward the back? Is it concentrated in the middle, or is a lot of it in the very ends? Are you lifting both ends at the same time, or one end at a time?
Apr
10
comment On the Existence of Interstellar Meteoroids
Maybe you could provide a link to the video, and what is 36:45? Thanks.
Apr
10
comment Why is there this asymmetry between the two foci of an orbital ellipse?
@EmilioPisanty: Thanks. You're right - except that the center of the cone is not the center of the ellipse, except for a circle. Easiest way to see that is to cut the cone on a plane almost, but not quite, parallel to the edge, so as to create an ellipse of very high eccentricity.
Apr
8
comment How “earthing” electricity work?
+ @MukulKumar: They don't. The reason the earth is conductive is because it contains a certain amount of water, and plenty of ions in that water.
Apr
6
comment Beryllium Vacuum Sphere Boat/Aircraft
In air, the weight of air excluded from a given volume decreases with altitude, so a balloon of fixed volume has an altitude limit. High altitude balloons must be capable of expanding.
Mar
31
comment Water falling, why does it spin?
It is very difficult to make a faucet, or pour from a cup, without imparting some rotation to the water. As @Parth said, it will rotate faster as the diameter of the stream decreases.
Mar
28
comment Toy helicopters at very high altitude
@GlenTheUdderboat: Maybe a bit. What ground effect does is increase the lift/drag ratio.
Mar
19
comment Can an extremely small force lift a mountain in a hydraulic system? If not, then why not?
Just a tip: When I hear "If not, then why not?" I go uh-oh - sounds like a homework question.
Mar
18
comment How do birds generate thrust?
You may enjoy reading some or all of John S. Denker's on-line book about aviation. It will answer all your questions better than I can.
Mar
18
comment How do birds generate thrust?
The trouble is, it's not that simple. That would only work if the air could not escape around the wing and if somehow more air were propelled to the rear. (I think Einstein said find the simplest possible explanation - but no simpler :)
Mar
16
comment Does a resistor absorb and dissipate energy or just regulate the charge flow?
@GM: No, because in any moment in which there is a voltage across the resistor and a current flowing through it, energy is lost. A resistor will lose it through heat. Something like a motor will lose it through mechanical work. A capacitor or inductor will lose it by building up energy in its field. For a resistor, it will generate heat - there's no other way for it to behave.
Mar
13
comment Why does air circulate on an airfoil — The Kutta Condition
Where you got that picture is a better explanation than I could ever give.
Feb
25
comment No-slip condition when one fluid flows through another
yes............
Feb
21
comment Relationship between engine Speed at maximum power and torque
Power is the product of torque and RPM, so naturally they will occur at different speeds. You get to an RPM where if you increase the RPM by a little bit, the torque falls by a little bit, but the product of the two stays the same. Like at about 5.5k in your picture.
Feb
19
comment Where / what is the source of the force that causes refraction?
Photons have no mass. Their energy is not kinetic. It is a function only of their frequency.
Feb
19
comment Picking up audio using high speed video?
There is however this gadget that uses radio rather than light.
Feb
18
comment Pascal's Principle and hydraulic lift
@John: Right. My simplistic analogy is pushing against a spring. You can't exert a certain force against it without also compressing it.