Shameless Plug

Guy Macon wrote in news: snipped-for-privacy@corp.supernews.com:

Could it just be because tachs have no polarization standard? If your system runs away, flick the switch!

Scott

Finally someone who speaks my language!

The first clear, concise, and lucid post in quite a while!

A little off track at first, but you wrapped it up nicely towards the end! :o)

Louis--

********************************************* Remove the two fish in address to respond

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Engineering is the art of making what you want from things you can get.
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The "D" part of PID refers to the presence of a rate-of-change term, often able to be interpreted as a derivative of a position (or similar) quantity. Derivatives are a concept deriving (!!) from the differential calculus. Either term refers to the notion of infinitesimal differences whose ratios are considered as they approach (under suitable existence conditions) some limiting value.

Thus either version of the acronym is fine. Elsewhere in this thread is a timely reminder about the danger of reliance upon statistics (eg: Google hits) to "prove" something. I've come to the conclusion that if the majority agree upon something, it's probably false (works great in the stock market, but you have to be careful about your audience when defining the principle as "the fallacy of democracy"......)

Geoff.

Not acording to Sturgeon's Law:

90% of everything is C%&p

But that was before the internet - Internet Corollary to Sturgeon's Lwa:

99% of everything is C%&p

Bruce

Nicholas O. L>>Why do half the engineers call [PID] "Proportional-Integral-Derivative"

["Followup-To:" header set to sci.electronics.design.] On Tue, 30 Nov 2004 08:59:24 -0800, Tim Wescott wrote in Msg.

This reminds me of one of my favorite entries in Strunk & White, Modern English Usage on "flammable" vs. "inflammable". The correct term is inflammable, but on trucks that hold dangerous goods you'll always see "flammable". Quoting from memory: "Unless you drive such a truck, and are hence concerned with the safety of children and illiterates, use inflammable".

According to my pedantic mind, there's no such thing as a flammable substance, but the general public seems to think otherwise.

--Daniel

...

Bravo!

Jerry

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Engineering is the art of making what you want from things you can get.
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So you derive from deriving the derivative from the differential that one should not differentiate between differential and derivative? That's different.

Google hits prove commonness of usage on the World Wide Web. All else is derivative - an important difference.

The meaning of flammable is clear, while inflammable might be disastrously confused with unflammable (not a real word either) meaning non-flammable. The need for clear disambiguation on gasoline tankers trumps the joys of pedantry.

Jerry

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Engineering is the art of making what you want from things you can get.
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The meaning of flammable is clear, while inflammable might be disastrously confused with unflammable (not a real word either) meaning non-flammable. The need for clear disambiguation on gasoline tankers trumps the joys of pedantry.

Jerry

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Engineering is the art of making what you want from things you can get.
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snip

Maybe it's just me, but shouldn't this be obvious to anyone who's had even basic physics in school?

-Lasse

OTOH ...

One of the early power system simulation packages developed (I think) by IBM (dates from the days of punched cards so that gives an indication) had a reasonably well documented (for those days) program, luckily...

In the main body of the program prior to calling a subroutine to simulate the voltage regulator was a line of code that reversed the sign of a variable, with a brief note to state that the standard equation assumed the quantity was positive when it was actually negative (or something). Immediately after the start of the subroutine was a line of code that reversed the sign of the same variable, with a brief note to state that the standard equation assumed the quantity was positive when it was actually negative.

We found this after several days of wondering why the simulation of a power system transient indicated an unstable voltage regulator.

But I guess if you get the action of controller wrong it's nice to be able to reverse it very quickly - hopefully before the operators notice!

Bruce

Tim Wescott wrote:

...

That really peaks (or is it peeks?) my ire. :-)

...

Jerry

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Engineering is the art of making what you want from things you can get.
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Piques. I'm prescriptive.

Years ago there was a weekly puzzle in our newspaper which used exactly that principal, they would give clues (no, not clews) that required a true prescriptive knowledge to answer. For example, they would give a clue along the lines of "to overwhelm with fauna" and the crossword would be filled in except for one letter. In this case the crossword would contain INFE?T. It would be up to you to choose between INFECT and INFEST.

There was a $500 dollar prize for the correct answer to the crossword, which probably neede you to fill in only about 12 letters as explained above. I won twice over a period of 12 years.

I don't think they run that puzzle anymore.

Only those who went to school back when they were still teaching how to apply basic physics to real-world problems.

To be fair, some schools do a great job of this, but I have personal experience of a person who got an EE degree from a state college without ever tumbling on to the fact that when you send current down a wire there has to be an equal current through a return path. :(

That engineer was put to work maintaining COBOL programs. This was in the '90s, not in the age of COBOL.

My apologies.

Essentially yes. (Ignores irony). But then, I'm not only a mathematician, I'm also a linguistics freak....

As I intimated, "common usage" is to be distrusted. After all, the planet's population is now so large that virtually any human-behavioural parameter, via the central limit theorem, gets modelled as obeying a Gaussian distribution, whose *central* area dominates the sample results. I call the universal welcome currently accorded to this situation "the cult of mediocrity" and it is an example of positive feedback. Examples abound. Think about it.

The linguistics scene has "descriptive grammarians" (currently in the ascendant) versus "prescriptive grammarians" (started declining maybe 50 years ago). That's why I regularly find books, and even learned papers, which confuse "throes" with "throws", "pour" with "pore", and many more, since schools ceased to bother students with (horror!) rules, substantive examinations etc.

To pull things together: my derivative/differential fusion is based upon a return to fundamentals (mathematical and linguistic). I find that this approach is superior to all others I've tried. YMMV.

Geoff.

Good for you. I was being sarcastic (and rueful). I assumed that the "peek" would signal that I was poking fun.

Congratulations! (No sarcasm.)

Too bad.

Jerry

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Engineering is the art of making what you want from things you can get.
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...

That's a humdinger!

Troll and trawl may be related linguistically and used interchangeably in some places, but trolling in fresh water is trailing a fishing line from a moving boat. Perhaps that use connects trail to troll and trawl. Perhaps I'll look into the etymology; if I do, I'll report.

Jerry

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Engineering is the art of making what you want from things you can get.
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