blacksmythe

Sounds like one solution would be to apply a sealant that looks like bare concrete.

Caltech - where your best just isn't good enough.

  https://www.flickr.com/photos/pixieza/79223350

It is amazing how much less time it takes to pay off a 30 year mortgage if you increase the payments 10%. The first good many years are paying mostly just the interest.

Kinetic energy is a good measure for a baseball, because essentially all of the kinetic energy is being transferred from the small object to you.

Kinetic energy is not a good measure for a car or B-52, as after the collision the large object has essentially the same kinetic energy, and a very small fraction has been transferred to you.

A bicycle is more toward the small object side, as a pedestrian is going to absorb a good fraction of the kinetic energy of the rider, which is much larger than the kinetic energy of the bicycle itself.

  >> Taking the FFT, modifying frequency amplitudes

Modifying amplitude and phase. In the time domain you can't modify frequency amplitude without modifying the phase. If you modify just the FFT amplitude, you can end up with non-causal impulse responses.

AMA95 is one of the few Caltech classes that I still think about, mostly because it was not useful. Almost all of my other classes have been useful over the years.

I wish that the math sequence for non-math majors had included linear algebra instead.

  >> makes sure to walk the trainees through the confusing states you can get into, 
  >> then we explain what happened, why, and how to correctly get out of them

Is this something you could share?

I don't travel with an extra keyboard, but I do take a mouse.

An external mouse is so much better, and hardly takes up any space.