7,000 reputation
1524
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 2 years, 11 months
seen 20 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.


Jul
13
comment Why is an Aircraft Runway NOT like a Teaspoon?
@Willie: Check this view of a short final. It looks like the plane is high but it's not. That's because of the slope of the runway.
Jul
13
comment Why is an Aircraft Runway NOT like a Teaspoon?
@Willie: My favorite example of this is Lukla, Nepal. The runway is only 1500', with a 12 degree slope. There's a stone wall at one end and a cliff at the other. So you land up-hill and take off down-hill.
Jul
12
comment Why is an Aircraft Runway NOT like a Teaspoon?
@J.C.Leitão: Right. Its weight is supported on its downward-thrusting jets (as you can see from the severely downturned flaps and tail), which is assisted by some upward acceleration from the ramp. Check the 2nd sentence here.
Jul
12
comment Why is an Aircraft Runway NOT like a Teaspoon?
+1 Good explanation. The object is not to get lofted into the air. The object is to reach a speed and angle of attack at which the wings can carry the weight.
Jul
11
answered Calculate quadrotor propeller torque due to aerodynamic drag
Jul
11
comment List of Physical Toys
don't forget arborsci.com/astro-blaster
Jul
11
comment Sound frequency of dropping bomb
+1 Also there's the simple geometry of the hearer's position relative to the path. If the hearer were on the path he or she would not report anything :( Otherwise, as the dot product of the projectile's velocity vector, and the hearer-projectile position vector approach and pass zero, the frequency shift would decline.
Jul
10
comment Paper plane between two fans - is this possible?
I'm a bit incredulous that the plane could remain so stable for so long. In principle it seems possible, if the airflow field is the right shape. It would seem to be radially diverging, because the plane seems to weather-vane "downhill" toward a particular point. It's hard to imagine such a well-controlled airstream, but I guess it's possible.
Jul
10
comment “Relativistic Baseball”
Then does the pitcher get a new contract?
Jul
9
answered What do spacecraft have in common with atmospheric aeroplanes?
Jul
7
awarded  Popular Question
Jul
5
comment Rubber Band Forces
The tension in a rubber band is locally linear, just like a spring, but actually rubber bands have a maximum length, even if breakage is not considered, because what you're actually doing is compressing it laterally. You can detect that as a temperature rise in the stretched band. There are even "heat engines" made with a rubber band and a heat source.
Jul
4
revised Why ballasted gliders fly faster
added 120 characters in body
Jul
4
revised Why ballasted gliders fly faster
added 554 characters in body
Jul
4
answered Why ballasted gliders fly faster
Jul
4
comment Why ballasted gliders fly faster
For a non-native English speaker, your English is very good.
Jul
4
revised What is the principle behind centrifugation?
added 37 characters in body
Jul
4
answered What is the principle behind centrifugation?
Jul
3
comment How can a laser pointer have range of several kilometers in atmosphere?
@anna: Are you saying it is a function of the aperture size the light is coming through? I mean, I can imagine incoherent light from a star (infinite r) being reflected off a 2cm-diameter mirror and shone at the moon. Would it diverge more simply because of the small mirror, than if it were coherent?
Jul
3
comment How can a laser pointer have range of several kilometers in atmosphere?
Sure the intervening atmosphere saps energy of the beam and spreads it out, but what do you mean by "range"? The distance at which its holder can see its spot? or the distance at which someone at the other end can see it?