[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: gEDA-user: [OFF] high current amplifier
John Doty wrote:
> On May 20, 2009, at 6:05 PM, Joerg wrote:
>
>> John Doty wrote:
>>> On May 20, 2009, at 2:36 PM, der Mouse wrote:
>>>
>>>>>> A ton of cooling is 12 Kbtu, about the heat of crystallization of
>>>>>> one ton of water, per hour.
>>>>>>> Why do engineers use so many whacky units?
>>>>>> [...], tradition and convenience.
>>>>> Good excuses for the masses. Not so good for engineering, which
>>>>> depends on precise communication.
>>>> Which measuring air conditioning capacities in tons provides. Just
>>>> because it's disorienting to those who are acquainted with only
>>>> other
>>>> meanings of the word doesn't make it any less precise.
>>> It's poor communication. Specialized jargon. Language should
>>> illuminate the issue to the widest possible audience. But here, even
>>> to specialists, the language obfuscates, since using the same units
>>> for heat and electrical energy would reveal the thermodynamic
>>> efficiency of the technology.
>>>
>> Depends on who you are dealing with.
>
> Of course. You have to be prepared to deal with this problem.
>
>> When I spec'd out a catheter
>> manufacturing plant the construction guys as well as the architact
>> looked at me with wrinkled foreheads when I started with kilowatts.
>> "So
>> what size unit goes where, then?" ... "Well, two five-ton units over
>> here and we'll need another one over yonder." ... "Ah, ok, I think we
>> can work that into the budget."
>
> And *you* did exactly right. But the other guys would find energy
> efficiency issues much easier to comprehend if they used consistent
> units.
>
Well, I am trying. In some areas you just have to stick to the old
conventions or nobody will understand. But I recently did (partially,
for data storage) move to the ISO date format after a few overseas
engineers "convinced" me ;-)
The topper was when someone at a Scottish heliport asked me how many
stones I weigh.
>> Same in other professions. Taking it back four inches doesn't mean
>> altitude in an aircraft ;-)
>>
>
> The first space mission I worked on did mass properties in slugs and
> feet, and magnetic properties in CGS units (pole-cm et al.). Since we
> were using magnetics to orient the spacecraft, that produced a
> collection of magic constants, both in the computer code and written
> on a crib sheet in the ops room. You can deal with it, but it's
> stupid to have to. And sometimes it produces catastrophic confusion
> (Mars Climate Orbiter).
>
Or it produces nailbiters like this one:
http://www.wadenelson.com/gimli.html
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user