Re: A thread that has nothing to do with memes or the

James Rogers (
Wed, 04 Dec 1996 10:28:41 -0800

>Coming back to the cell. A cruder form of this -- a sharpened rock --
>would be to design a protein that absorbs the vibrations of an adjacent
>protein in such a way as to calm it down, so to speak. To damp out
>its vibrations. To cancel its noise. That would have the effect of
>cooling it.
>This is basically a physics problem. The fact that the vibrating
>structures are proteins doesn't really enter into it. How does one design
>a vibrating structure that absorbs and damps out the vibrations of an
>adjacent structure?

There is a type of "active" composite that has the properties you are
describing. It is a laminate composite consisting of piezo-electric
ceramics and shape-memory alloys from the nickel-titanium family.

When vibrations hit the ceramic outer laminate, the ceramic acts as a
transducer, converting the vibration into an electrical signal. The signal
is inverted (It may be inverted via an anisotropic material property. I am
not sure.) and fed into the shape-memory alloy. The alloy flexes and
reproduces the inverted signal, similar to a speaker, through the ceramic.

The net effect is that the material nulls the vibration, but produces heat
with the excess energy. This composite is being considered for use as a
solid state vibration damping mechanism in macro structures such as aircraft
wings and sensitive machinery. I understand it is extremely effective.

A more advanced version of this technology is being studied for next
generation submarine stealth technologies. Preliminary tests indicate that
it is possible to make a submarine invisible to active sonar in this way.

-James Rogers