[Beowulf] Re: Beowulf Digest, Vol 15, Issue 16

[Jim Lux]

At 03:37 PM 5/10/2005, Lombard, David N wrote:
> >
> > Actually, the ideal "goal evaluator" is me, looking at the results of
> > several runs and comparing them, then telling the "box" which way to
>go
> > next. As you say, if you could define a goal function with sufficient
> > clarity, then any manner of optimizers could grind away on the problem
> > overnight.  Unfortunately, most real design problems have requirements
> > that
> > are a bit fuzzy:  Don't make it "too big" or "too flimsy".  terms like
> > "flimsy" are hard to encapsulate succinctly in a mathematical
>formulation
> > (although, gosh, we certainly try, by requiring certain mechanical
> > resonance properties and failure strengths). Much like other things,
>you
> > know them when you see them.
>
>Hmm, too "big" or "flimsy" have very precise definition based on exactly
>the measures you describe.  Such goal functions have been in use in the
>various structural optimizers for years now, e.g., weight, stress
>distributions, deflections, modal responses, &etc.


True, when you have hard specifications.  The hard part is negotiating a 
relative weight for each of these factors when doing the tradeoff, as is 
often the case in early trade studies.

That's where the "skilled evaluator" comes in.  A person with some years of 
experience can  integrate all those different factors fairly easily.



> > Aha... your idea has been anticipated!  Several people have done just
>this
> > (using a Beowulf, even, for the optimizing).  Randy Haupt did a fair
> > amount
> > of it with wire antennas (and others, I'm sure).  There was also
>someone
> > at
> > UCLA who designed wireless antennas using just what you describe
>(adding
> > and removing small patches of conductive surface).  They then
>fabricated
> > the antennas and tested them.
>
>Yes, there are a number of extant solutions using stochastic
>optimization in the automotive and aerospace manufacturers among others
>for these very purposes.  Clusters running in throughput mode are a
>really good engine for this work.
>
>--
>David N. Lombard
>
>My comments represent my opinions, not those of Intel Corporation.

James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875