8,422 reputation
1730
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 3 years, 8 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.


May
6
comment Does my (too low) tire pressure, affect the speedometer of my car?
I agree with this answer, on the assumption that the steel belts determine the outer circumference of the tire. If the tire is very flat, the tread gets squeezed tangentially as it moves through the contact patch, because it it taking a shorter path. This is not like a caterpillar tractor tread, unless the tire is allowed to slip tangentially along the rim, which I assume it is not. It will experience tangential stress, which might cause some slipping. Evidence of this would be the filler tube departing from being perpendicular to the rim.
May
4
comment Is a Super-luminal Laser spot possible?
Why fool with seconds? Suppose you see a supernova at one point in the sky, and one year later you see another at a different point. They are separated by millions of light years. Nothing "traveled" between them, except maybe our imagination.
May
3
comment How does a hovercraft hover, if it has low pressure underneath it?
I suppose they call it "low pressure" because it's lower than "high pressure".
Apr
29
comment Why is the water in a cup not inclined (opposite the cup) when the plane takes a turn?
Actually, airplanes can make a wings-level turn, just by pressing a rudder pedal, and in that case, you and your coffee do feel a sideways force. But it's slow, uncomfortable, and very inefficient, compared to just banking into the turn.
Apr
27
comment How to make a structure of which water flows out at a constant rate?
What you need is constant pressure. Check out carburetor.
Apr
27
comment How to make a structure of which water flows out at a constant rate?
The key is the float-operated valve. Carburetors have had this for a century.
Apr
23
comment Do rotating non-circular projectiles also experience Magnus lift?
Almost any method of inducing circulation produces lift by deflecting the airstream. Simple example: take a strip of paper 1/2" wide by a few inches long. Hold it the long way between your hands and drop it, with backspin. It keeps backspinning and glides quite nicely.
Apr
23
comment A moving brush on a vibrating surface
I suspect where the bristles touch the surface not completely vertical there is a ratchet action.
Apr
22
comment Why is the water in a cup not inclined (opposite the cup) when the plane takes a turn?
Because planes don't turn the way cars do, they turn the way bicycles do.
Apr
20
comment When we are inside a plane and look outside the window why does everything (outside) appear to be at rest?
When you see movies about flying, they try to make it exciting by zipping in and out between clouds, so you get a sense of speed. In real flying, you want it to be as boring as possible. You stay far away from clouds, and everything else, if you have a choice. Clouds are bumpy, they block your vision, and other planes can be hiding in them.
Apr
17
comment Why is wave a function of volts?
@user78162: Sure. You could go to an electronics store and buy a cheap voltmeter. Actually, what it measures is current through the little coil attached to the needle, but there's a resistor in series, so if you want to measure voltage, it does so. The trouble with a multi-meter is the needle is mechanical and can't move very fast. An oscilloscope trace can move faster and also show you the trace over time, that's all.
Apr
14
comment Why do we use capacitors when batteries can very well store charges?
I see your point.
Apr
14
comment Why do we use capacitors when batteries can very well store charges?
But if you time-integrate the current going into a capacitor, and coming out the other side, can't you call that "charge"? $I = dQ/dt$
Apr
9
comment Static pressure in relation to CFM
I would look up orifice flow and work from there.
Apr
8
comment Is it correct to say “like poles attract, unlike poles repel” while two magnets are placed such that one is inside another?
A solenoid coil is not like a bar magnet. It is like a sleeve around a bar magnet. The magnetic lines of force go down the inside and up the outside (or vice versa).
Apr
8
comment Can universe or anything be simulated with absolute accuracy?
@LifeH2O: Even if the hypothesis of copying the universe were possible, quantum randomness would make them diverge. Take a simpler example: two entangled electrons with opposite spins. As soon as you learn the spin of one you know the spin of the other, but from that point on, they evolve independently.
Apr
8
comment Can universe or anything be simulated with absolute accuracy?
@LifeH2O: That's a problematic hypothetical.
Apr
7
comment The velocity of air on an airfoil
The best site I know on how wings work.
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.