RE: [SI-LIST] : What's your favorite Screwy SI Concept?

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From: Chan, Michael (Michael.Chan@compaq.com)
Date: Tue Jan 11 2000 - 16:17:25 PST


The question still unanswered. How is the 20H rule being drawn up?
I don't care whether it is a good or bad rule. I just hope to know
how it is being drawn up. Hope this won't offend the other audiences
in this forum.
I do agree with Doug's explanation of using rule of thumb. I use other
people's rule of thumbs as well but I will try to verify it before it use
it.

-----Original Message-----
From: Grasso, Charles (Chaz) [mailto:GrassC@LOUISVILLE.STORTEK.COM]
Sent: Tuesday, January 11, 2000 6:03 PM
To: 'si-list@silab.eng.sun.com'
Cc: 'Doug Smith'
Subject: RE: [SI-LIST] : What's your favorite Screwy SI Concept?

Doug, an excellent answer - very eloquently put.

-----Original Message-----
From: Doug Smith [mailto:dsmith@corp.auspex.com]
Sent: Tuesday, January 11, 2000 3:46 PM
To: si-list@silab.eng.sun.com
Subject: Re: [SI-LIST] : What's your favorite Screwy SI Concept?

Hi All,

Buryed within the multiple responses to the 20H rule was the following
text:

> In the acknowledgements amongst other *Celebrities* is the name of DOUG
SMITH,
> for providing Technical review of the material. If he is the same as the
one
> on this list we may get some clarity over this.

At the time Mark was writing his first book, he did ask me to review it
and I started doing so. However, reviewing a book is a lot of work. At
the time, my work life was very intensive and did not permit me the time
to finish a review for Mark in the time he needed. I was able to provide
some input to Mark and felt honored that he asked me for it. It is a
sign of a good engineer/scientist to take into account technical input
from others, and Mark did that to his credit.

I build up experiments, time permitting, to test out theories and see
what kind of measured results I can get. The results of the latest board
layout experiment have been submitted to the IEEE EMC Symposium and we
(more than one author) hope to present the material next summer at the
Symposium. I have not done such an experiment yet for the 20H rule and
so have no data to present. With all the discussion, is anyone planning
such an experiment in the near future?

A word on rules of thumb... We all use rules of thumb every day in our
work and daily lives. These come from many sources and we cannot
possibly check them all out. For instance, Henry Ott's book is full of
rules of thumb and summaries of principles such as the equation for
radiation from a hole. Henry's book would have to be VERY long to
provide the proof of all of them. But, they are reasonable and come from
a knowledgeable source so we use them. Sometimes we misapply a principle
here or there but for the most part such an approach works (or we would
all be looking for work OR get very little sleep trying to check out
everything we read). If a rule of thumb makes sense given one's own
knowledge and experience and it comes from a reliable source, use it. It
is always good to generate our own data or proof on these matters, but
that is not always practical. Isn't this characteristic, that of
building on the work of others involving some trust, what distinguishes
human beings from animals, the ability to pass on information without
each generation having to continually regenerate it for themselves?

What really makes this work was said by Carl Sagen:

~"A good engineer or scientist must be willing to drop their most
cherished theories in the face of credible evidence to the contrary."
Note: ~".." means approximate quote. Maybe if I took more Ginko Biloba I
would remember the exact quote. :-)

Doug

-- 
----------------------------------------------------------
    ___          _          Doug Smith
     \          / )         Manager EMC Development & Test
      =========             Auspex Systems
   _ / \     / \ _          2300 Central Expressway
 /  /\  \ ] /  /\  \        Santa Clara, CA 95050-2516
|  q-----( )  |  o  |       Phone/FAX: 408-566-2157/2020
 \ _ /    ]    \ _ /        Email: dsmith@auspex.com
----------------------------------------------------------

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