6,947 reputation
1424
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 2 years, 10 months
seen 3 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.


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
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.
Feb
15
comment How much weight can a person carry to avoid being blown over by wind?
It does get windy between the buildings in Boston (or anywhere). I would go with @Carl's suggestion of a cane, especially one that is adjustable and collapsible, and that has a strap or hook so you can free up both hands without dropping it. The trouble with a rolling bag is just that - it rolls, so it may not give as much stability as you'd like. Good luck. (Just thought of another possibility - a 4-wheel bag that you can lean on while it rolls - maybe?)
Feb
11
comment water in vacuum(or space) and temperature in space
Take a beaker of water out of the space station and remove the lid. First the water will float out, then it will boil away because of no pressure, and the vapor will fly away. If you kept it under pressure so it could not boil off, then it would either 1) get hot when the sun shone on it, or 2) get cold in the shade, because it would radiate its heat away to the sky, which is practically at absolute zero.
Feb
8
comment How can a fly be in the space of a roofless car, get out of the car space and get back in while the car is driving at the speed of 80mph?
Maybe relevant. My cousin is a long-time pilot. He has heard of people who wished to have their ashes spread from an airplane. What a mess! The dust blows everywhere and they have a big cleanup job.
Feb
6
comment Can you read and write a quantum state to a particle without collapsing its probability field?
Writing information to it before a computation is no problem. After it has started, you cannot touch it until it is finished, at which time you can read it. You may not get the right answer. You have to arrange the computation so that the right answer has an acceptably high probability.
Feb
4
comment Calculate work done in an inclined plane
@mc8: Then you're not elevating it, right? So you're not putting in any potential energy. You might give it kinetic energy, if you push it and it just keeps on moving. That's when your F=ma comes into play.
Feb
3
comment Calculate work done in an inclined plane
@mc8: Glad you got it. You're welcome.