HDTenEightyP/NetNews huggingface dataset:
From: neufeld@helios.physics.utoronto.ca (Christopher Neufeld)
Subject: Re: Superconductors
Organization: University of Toronto Physics/Astronomy/CITA
Date: Tue, 18 Aug 1992 08:11:57 GMT

In article <1992Aug18.060748.2986@ee.eng.ohio-state.edu> rob@guinness.eng.ohio-state.edu (Rob Carriere) writes:
>In article <1992Aug17.092101.25220@odin.diku.dk> nomann@diku.dk (Ole Nomann
>Thomsen) writes: 
>>tmyoung@mailbox.syr.edu (Thomas M. Young) explained to me via E-mail:
>>2. The critical magnet field is large*, so you could store energy in 
>>   a big magnet instead (many loops of sc wire).  It would have to be big, to
>>   solve the cooling energy problem, and it would try to tear itself apart.
>>   This is _dangerous_.
>
>No matter what the critical current density, that's your _only_ option.  The
>electrical energy stored in the loop is I^2*R, and since R=0...
>
   No, the electrical energy stored in the loop is I^2 * L / 2. L, the
inductance, is not zero. However, this expression for stored energy is
rigorously equal to the energy stored in the field, the integral over all
space of one half the dot product of the 'B' and 'H' vectors. They're two
different ways of expressing the same thing.

>As for it being dangerous, that's by definition.  Large amounts of energy
>are dangerous, period. [...] A magnetic field is probably one of your
>more obnoxious storage methods in this regard, though.
>
   I don't know why you think magnetic storage is any more dangerous than
any other. A well designed superconducting coil doesn't dump the field in
seconds even during a quench. We have a superconducting magnet which
occasionally quenches, dropping 200 kilojoules into the helium vessel. We
can have the magnet up and running again in a couple of hours, at the
cost of a few dozen litres of liquid helium. Of course our helium
recovery system is incapable of taking the helium flow during a quench,
so we lose the evaporated gas during a quench, but even that is not an
inevitable cost of running a superconducting coil.
   I expect I'd be more comfortable with a superconducting coil storage
system than with, say, a compressed air energy storage system which
pumped tens or hundreds of megawatt-hours in energy into a salt dome for
recovery by turbines. At the moment, though, there are no practical
large-scale energy storage systems in common use. They're not really
needed for the current crop of base load power plants like coal and
nuclear. If solar or wind power were ever asked to take up the base load
we would need some better electricity storage systems for leveling these
intrinsically erratic generating schemes.

-- 
 Christopher Neufeld....Just a graduate student  | Confidence is the feeling
 neufeld@helios.physics.utoronto.ca    Ad astra  | you have before you
 utzoo.utoronto.ca!generic!cneufeld              | understand the situation.
 "Don't edit reality for the sake of simplicity" |
Newsgroups: rec.arts.sf.science
From: daveh@xtenk.wpd.sgi.com (David Higgen)
Subject: Re: Superconductors
Organization: Silicon Graphics, Inc.  Mountain View, CA
Date: Thu, 20 Aug 1992 22:16:37 GMT

In article <Bt6yD6.AGn@helios.physics.utoronto.ca>, neufeld@helios.physics.utoronto.ca (Christopher Neufeld) writes:
> In article <1992Aug18.145005.7655@porthos.cc.bellcore.com> ccw@prefect.uucp (26554-wood) writes:
> >
> >I've read about hydro energy storage systems.  During the night, they
> >run separate pumps to put more water back into the reservoir from down
> >below.  During peak demand, they can run more water through the
> >turbines, and generate more electricity.
> >
>    Yes. I knew some had been approved for construction, but are there any
> which are actually being used for that purpose by utilities at the
> moment, as opposed to prototype or proof of concept plants?
>    Anyway, they're certainly not in common use right now.

Don't know about the US, but there is a fairly large one operational in
the UK (Dinorwic, North Wales). At least, it was built somewhat over 10 
years ago & I assume is still in use.

I don't offhand recall the capacity, but I think it's a fairly
respectable number of hundreds of megawatts.


		Dave Higgen (daveh@xtenk.wpd.sgi.com)
From: pjh@eng.cam.ac.uk (Philippa Hogben)
Newsgroups: rec.arts.sf.science
Subject: Re: Superconductors
Date: 19 Aug 92 10:23:40 GMT
Organization: cam.eng

neufeld@helios.physics.utoronto.ca (Christopher Neufeld) writes:

>In article <1992Aug19.061628.5126@ee.eng.ohio-state.edu> rob@guinness.eng.ohio-state.edu (Rob Carriere) writes:
>>In article <Bt66ry.H2B@helios.physics.utoronto.ca>
>>neufeld@helios.physics.utoronto.ca (Christopher Neufeld) writes: 
>>>In article <1992Aug18.060748.2986@ee.eng.ohio-state.edu>
>>rob@guinness.eng.ohio-state.edu (Rob Carriere) writes: 

[stuff deleted]
>>
>   Not at all. Look, I can take a superconducting inductor and apply a
>voltage to it. It draws current by the familiar V = L dI/dt, and hence
>absorbs power at the rate of V * I. Later I can extract the energy from
>the loop by putting the inductor across a resistance. I've stored
>electrical energy. I happen to have stored it in a magnetic field, but so
>what? Does a rechargeable battery store electrical energy or chemical
>energy? The energy stored in a superconducting loop is certainly entirely
>different from I^2 * R, since that represents the instantaneous power
>dropped in a load.

You have stored _energy_ in the magnetic field, not _electrical_energy_.
"Energy may be freely converted from one form to another." [Who said that?]


Philippa
--
Philippa Hogben   pjh@eng.cam.ac.uk  (Reverse if mailing from Janet)
Any mistakes are mine, all mnie.

I am not a .sig virus. I am a free bug.
From: urlichs@smurf.sub.org (Matthias Urlichs)
Newsgroups: rec.arts.sf.science
Subject: Re: Superconductors + the 2nd law
Date: 16 Aug 1992 22:19:20 +0200
Organization: University of Karlsruhe, FRG
NNTP-Posting-Host: 127.0.0.1

In rec.arts.sf.science, article <BCR.92Aug11213930@hpl3sn02.cern.ch>,
  bcr@cernapo (Bill Riemers) writes:
> In article <1992Aug10.083035.15182@ccu1.aukuni.ac.nz> ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:
> 
>    Minor quibble there - producing no waste heat is impossible if you are 
>    using a computer which clears data; for every bit you clear, you
>    produce a certain amount of entropy (ln(2)*K, where K is Boltzmann's
>    constant, or something like that).
> 
> No problem... Who says we have to erase bits to a disorganized state?
> Also, who says we can't keep the number of disorganized bits relatively
> constant?  (i.e. You organize the same number of bits you disorganize.)
> 
Unfortunately, there's a second problem -- computational stability, and/or
immunity to noise. You have to get that 0.5 V at your gate input back to 0.2
V (or whatever) at the gate output; if not, your computer will be in a very
randomized state very soon.
Thus you're reduing the number of states your machine can be in --> loss of
information --> entropy increase --> heat --> back to the drawing board. ;-)

-- 
The doctrine of human equality reposes on this: that there is no man
really clever who has not found that he is stupid.
		-- Gilbert K. Chesterson
-- 
Matthias Urlichs  --  urlichs@smurf.sub.org -- urlichs@smurf.ira.uka.de   /(o\
Humboldtstrasse 7 -- 7500 Karlsruhe 1 -- Germany  --  +49-721-9612521     \o)/
From: trip@cco.caltech.edu (Trip)
Newsgroups: rec.arts.sf.science
Subject: Re: merpeople
Date: 17 Aug 92 22:20:07 GMT
Organization: California Institute of Technology, Pasadena

kathrynw@radian.UUCP (Kathryn Whitworth) writes:

>These merpeople do live in oceans rather than freshwater.

>Within these limitations, it seems that they would need to be able to pull
>O2 from sea-water without the salt frying their gills.  This would imply a
>different amount of salts in the bloodstream, would it not?  Otherwise
>osmosis would do them in?

Nope. Blood (human or otherwise) is seawater with a few cells floating
in it. *Fresh* water is what would eat their gills. It messes up human
lungs, in fact, although there usually more urgent problems to deal with
if your lungs are full of fresh water.

Trip				|   Everybody's playing the game
President, ECNG			|   But nobody's rules are the same
(trip@cobalt.cco.caltech.edu)	|   Nobody's on nobody's side
				|			-_Chess_
Newsgroups: rec.arts.sf.science
From: rob@guinness.eng.ohio-state.edu (Rob Carriere)
Subject: Re: Superconductors
Organization: The Ohio State University Dept of Electrical Engineering
Date: Tue, 18 Aug 1992 06:07:48 GMT

In article <1992Aug17.092101.25220@odin.diku.dk> nomann@diku.dk (Ole Nomann
Thomsen) writes: 
>tmyoung@mailbox.syr.edu (Thomas M. Young) explained to me via E-mail:
>2. The critical magnet field is large*, so you could store energy in 
>   a big magnet instead (many loops of sc wire).  It would have to be big, to
>   solve the cooling energy problem, and it would try to tear itself apart.
>   This is _dangerous_.

No matter what the critical current density, that's your _only_ option.  The
electrical energy stored in the loop is I^2*R, and since R=0...

As for it being dangerous, that's by definition.  Large amounts of energy are
dangerous, period.  You're going to have the some such problem with any kind
of battery (For example,  droppping a wrench on your car's battery is bad for
your health...)  A magnetic field is probably one of your more obnoxious
storage methods in this regard, though.

>No .sig, since it has been warlorded at least twice (why tempt fate).

Eh? Warlorded?

SR
---

Newsgroups: rec.arts.sf.science
From: wcstom@alfred.carleton.ca (Tom Hamill)
Subject: Aquatic mammals (Was Re: Merpeople)
Followup-To: rec.arts.sf.science
Organization: Carleton University, Ottawa, Canada
Date: Fri, 14 Aug 1992 14:56:29 GMT



In article u894793@bruny.cc.utas.edu.au (Timothy D Little) writes:
>
>   [deleted discussion on efficiency of gills]
>
>However, your original problem would presumably be that gills could not 
>support a mammal the size of a human, underwater.  (Correct me if not)
>
>Strange - aren't whales mammals?
>
It has always been my impression that aquatic mammals, such as whales
and porpoises(sp?), are air breathers, hence the whaler's cry of 
"Thar she blows!" when the animal surfaces and exhales.  

Or have I simply watched one too many reruns of 'Moby Dick'?

---tom

l~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~l
l      CRUSH---CompassionRespectUnderstandingSelfHonesty---CRUSH      l
l         How could you have ever lived your life without it?         l
l               Join Now, Apply Within.  Spread the word.             l
l____________________________      ---me, trying to save the world,   l
l wcstom@alfred.carleton.ca l                      from itself.       l
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Newsgroups: rec.arts.sf.science
Subject: Re: Superconductors
From: ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig)
Date: Tue, 18 Aug 1992 22:06:04 GMT
 <Bt66ry.H2B@helios.physics.utoronto.ca> <1992Aug18.145005.7655@porthos.cc.bellcore.com> <Bt6yD6.AGn@helios.physics.utoronto.ca>
Organization: University of Auckland, New Zealand.

neufeld@helios.physics.utoronto.ca (Christopher Neufeld) writes:

>In article <1992Aug18.145005.7655@porthos.cc.bellcore.com> ccw@prefect.uucp (26554-wood) writes:
>>In article <Bt66ry.H2B@helios.physics.utoronto.ca> neufeld@helios.physics.utoronto.ca (Christopher Neufeld) writes:
>>>In article <1992Aug18.060748.2986@ee.eng.ohio-state.edu> rob@guinness.eng.ohio-state.edu (Rob Carriere) writes:
>>
>>>At the moment, though, there are no practical
>>>large-scale energy storage systems in common use. 
>>
>>I've read about hydro energy storage systems.  During the night, they
>>run separate pumps to put more water back into the reservoir from down
>>below.  During peak demand, they can run more water through the
>>turbines, and generate more electricity.
>>
>   Yes. I knew some had been approved for construction, but are there any
>which are actually being used for that purpose by utilities at the
>moment, as opposed to prototype or proof of concept plants?
>   Anyway, they're certainly not in common use right now.

Germany has some of these. Their overall efficiency is not very good
(around 70 % or so), but it saves on the more expensive fuel types
for peak - load demand. They operate on a daily cycle. If I remember
correctly, they are located in northern Germany.
-- 
Thomas Koenig, ecmtwhk@ccu1.aukuni.ac.nz, ib09@rz.uni-karlsruhe.de
The joy of engineering is to find a straight line on a double logarithmic
diagram.
Newsgroups: rec.arts.sf.science
From: baylor@force.ssd.lmsc.lockheed.com
Subject: Re: merpeople
Reply-To: baylor@force.ssd.lmsc.lockheed.com
Organization: LMSC, Sunnyvale, California
Date: Wed, 19 Aug 92 18:58:22 GMT

In article <1992Aug17.222007.14757@cco.caltech.edu>, trip@cco.caltech.edu (Trip) writes:
>kathrynw@radian.UUCP (Kathryn Whitworth) writes:
>
>>These merpeople do live in oceans rather than freshwater.
>
>>Within these limitations, it seems that they would need to be able to pull
>>O2 from sea-water without the salt frying their gills.  This would imply a
>>different amount of salts in the bloodstream, would it not?  Otherwise
>>osmosis would do them in?
>
>Nope. Blood (human or otherwise) is seawater with a few cells floating
>in it. *Fresh* water is what would eat their gills. It messes up human
>lungs, in fact, although there usually more urgent problems to deal with
>if your lungs are full of fresh water.
>
Guess again. Human blood has the same salts as seawater, but in a 
lower concentration. (Frequently this is taken as evidence of the
seas having gotten saltier over the past ?? milenia). This is why
you can not drink seawater to quench your thirst. Sure you add water,
but you also add way too much salt.
Newsgroups: rec.arts.sf.science
From: jacob@cs.swarthmore.edu (Jacob Mattison)
Subject: Re: Human flight.
Organization: Swarthmore College
Date: Wed, 12 Aug 1992 21:23:51 GMT

In the Robert A. Heinlein short story "The Menace From Earth", which is in
the book of the same name, the (human) inhabitants of Luna City fly using
mechanical bird wings in an enormous cave that is used as an air storage
tank.  So the gravity is 1/6 Earth's, but the air pressure is higher than
on Earth.  He describes the wings very carefully; they apparently work
identically to a real bird, and are easy to use.  Presumably, then, in such
an atmosphere/gravity situation humanoids with real bird wings could fly.
But could such high pressure exist along with such low gravity if it weren't
artificial (as in this story, where the air is pumped into a sealed cave)?
                                                         Jacob
-- 
                              Jacob Mattison
jacob@cs.swarthmore.edu                    If God meant people to be bisexual, 
jmattis1@cc.swarthmore.edu                 she'd have made two sexes.
"It's a thingie!  A fiendish thingie!" -George Harrison, _Help_
From: artn@bert.eecs.uic.edu (Ellyn Sandor)
Newsgroups: rec.arts.sf.science
Subject: Re: Simultaneous events and frames of reference?
Date: 12 Aug 92 21:19:35 GMT
Organization: University of Illinois at Chicago


	There's two things to relativity I don't get.

(both of these have probably been beaten to death, so give me the short
answer, please)

1) The twin paradox.  Twin O (old) stays home and twin Y (young) goes
for a ride.  Fine, time slows down for the person accelerating .  But wait!
Motion, acceleration, etc. is relative, right?  So, relative to twin Y,
twin O is moving. Or is it purely acceleration (which is relative over
time to ones last frame of reference) which causes time dilation. Or
something like that. Anyway, my point is, if relativity means there are no
privelaged (sp?) reference frames, why does the twin who goes away get to
stay younger? 

2) If you have a disk with a circumference of one light year, and rotate
it at the rate of one revolution per year, does it shrink?  I suspect the
answer to that has something to do with points moving in a circle being
in constant acceleration, so if neccessary, modify the question so that 
a point on the edge has a tangential speed close to that of light.  It
seems that the disk should shrink, since relativity doesn't really care
whether you end up in the same place, and if a point on the disk is moving
at the speed of light, that would be an impossibility, so the disk must
contract in order to prevent it (which is also a length contraction
tangentially)

Thanks for treating my ignorance gently.

		Stephan
-- 
--
Stephan Meyers | artn@uicbert.eecs.uic.edu
(Art)^n Laboratories, inventors of the Stealth Negative PHSCologram
(312) 567-3762
From: pjh@eng.cam.ac.uk (Philippa Hogben)
Newsgroups: rec.arts.sf.science
Subject: Re: Superconductors
Date: 19 Aug 92 10:19:20 GMT
Organization: cam.eng

nickh@CS.CMU.EDU (Nick Haines) writes:

>In article <Bt6yD6.AGn@helios.physics.utoronto.ca> neufeld@helios.physics.utoronto.ca (Christopher Neufeld) writes:


>	[hydro energy storage systems]

>      Yes. I knew some had been approved for construction, but are there any
>   which are actually being used for that purpose by utilities at the
>   moment, as opposed to prototype or proof of concept plants?

>Yes, there are. There's at least one in Wales, 

Dinorwic. Plus at least one other that we saw while near Ffestiniog
(North Wales).

>and I think at least
>one other somewhere else in Britain. Actively used to store overnight
>excess from the National Grid.

Plus at least one (that I know of) in Luxembourg. Another poster
mentioned some in Germany - they seem fairly common here in Europe.

Philippa
--
Philippa Hogben   pjh@eng.cam.ac.uk  (Reverse if mailing from Janet)
Any mistakes are mine, all mnie.

I am not a .sig virus. I am a free bug. 
Newsgroups: rec.arts.sf.science
From: kellmer@milton.u.washington.edu (Brent Kellmer)
Subject: Dinos and Dragons
Reply-To: kellmer@u.washington.edu
Organization: University of Washington, Seattle
Date: Fri, 21 Aug 1992 15:38:00 GMT

As Nick Haines (nickh@CS.CMU.EDU) put it, the Nemesis hypothesis _is_ 
highly in doubt:  Sorry if I didn't make it very clear.  It fits, more
or less, the idea that there are cyclical extinctions, but even that is
in doubt.  A fascinating idea, though.  A good account of the idea is
in the book _Nemesis_ by the experimental physicist who spearheaded the
hypothesis, whose name I can't remember right now.  Fairly good reading,
and it gives a good account of the Alvarez team and their work on the 
K-T boundary and it's cause.

-Brent


Newsgroups: rec.arts.sf.science
From: singley@helix.nih.gov (Erick D. Singley)
Subject: Re: Dinos and Dragons
Organization: (National Institutes of Health, Bethesda, MD)
Date: Fri, 21 Aug 1992 15:53:47 GMT

This from memory from a short news piece. Anyone else hear it (98 rock, 8:00)?


Erick
From: urlichs@smurf.sub.org (Matthias Urlichs)
Newsgroups: rec.arts.sf.science
Subject: Re: Superconductors
Date: 16 Aug 1992 22:24:04 +0200
Organization: University of Karlsruhe, FRG
NNTP-Posting-Host: 127.0.0.1

In rec.arts.sf.science, article <1992Aug13.122812.8253@monu6.cc.monash.edu.au>,
  ins894r@aurora.cc.monash.edu.au (Aaron Wigley [Wigs]) writes:
> 
> When better lithography processes are used to layer chips, then this
> benefit you mention about higher densities will come about, without the
> help of superconductors. Visible light Lithography isn't used any more,
> and X-Rays have a limited resolution, so perhaps they will start etching
> with Gamma radiation?
> 
If I remember correctly, some people are already experimenting with the
particle equivalent, i.e. electron beams. I think there was an article in
Scientific American a few months back.

-- 
Auribus teneo lupum. (I hold a wolf by the ears.)
-- 
Matthias Urlichs  --  urlichs@smurf.sub.org -- urlichs@smurf.ira.uka.de   /(o\
Humboldtstrasse 7 -- 7500 Karlsruhe 1 -- Germany  --  +49-721-9612521     \o)/
Newsgroups: rec.arts.sf.science
From: rolf@geoserv (Rolf Wilson)
Subject: Re: merpeople
Reply-To: rolf@geoserv.isgs.uiuc.edu
Organization: University of Illinois at Urbana
Date: Thu, 20 Aug 1992 13:48:51 GMT

baylor@force.ssd.lmsc.lockheed.com writes:

>Guess again. Human blood has the same salts as seawater, but in a 
>lower concentration. (Frequently this is taken as evidence of the
>seas having gotten saltier over the past ?? milenia). This is why
>you can not drink seawater to quench your thirst. Sure you add water,
>but you also add way too much salt.

According to what I have been told (I've certainly never tried it)
there is sometimes a reason to drink seawater. Eventually, the salt
buildup will kill you, but dehydration can kill you much faster, if
say you are in a lifeboat under a blazing sun. Drinking the salt 
water might keep you alive long enough to be rescued, at which time
you would need large amounts of fresh water to flush out the salt.
-- 
Rolf Wilson     Illinois State Geological Survey    rolf@geoserv.isgs.uiuc.edu
Newsgroups: rec.arts.sf.science
From: jonathan@chpc.utexas.edu (Jonathan Thornburg)
Subject: Re: Evolution under High Gravity
Followup-To: jonathan@einstein.ph.utexas.edu
Summary: 2nd recommendation for Hal Clement "Mission of Gravity"
Keywords: gravity high strong intense Hal Clement Mission
Organization: U of Texas at Austin / Physics Dept / Center for Relativity
Date: Tue, 18 Aug 92 03:31:02 GMT

In article <doom.714038580@elaine36.Stanford.EDU>
doom@leland.Stanford.EDU (Joseph Brenner) writes:
>[ in a discussion of what life would be like in a high-gravity environment ]
>
>You can also take a look at Hal Clement's _Mission of
>Gravity_, a classic work about aliens on a high gravity
>planet.  Once again, Clement votes for "short": they're
>around the size and shape of Scorpions. 

Another recommendation for this book:  the ending contains a
really beautiful and (to me) very evocative and moving discussion
on the meaning of "science" as an ethos.  Highly recommended,
++good, etc etc.

- Jonathan Thornburg
  <jonathan@einstein.ph.utexas.edu> or <jonathan@hermes.chpc.utexas.edu>
  University of Texas at Austin / Physics Dept / Center for Relativity
  and (for a few more months) U of British Columbia / {Astronomy,Physics}
From: kuijt@umiacs.umd.edu (David Kuijt)
Newsgroups: rec.arts.sf.science
Subject: Re: Merpeople
Date: 13 Aug 92 21:29:04 GMT
Organization: UMIACS, University of Maryland, College Park, MD 20742


Kathryn Whitworth asks for thoughts about gills;

Gills have one big advantage over lungs: lungs are a sack.  We fill
them with air, allow the alveoli (sp?) to do their thing (passive
CO2 for O2 exchange), then we expell the air and start over.  Gills,
on the other hand, work continuously.  The fish/shark/whatever
keeps a constant flow of water through a fancy tube (or set of them)
in which are set frills containing the gill-equivalents of alveoli
which do their thing (passive CO2 for O2 exchange) constantly.
This allows continuous effort, rather than the gulp/expel technique
us earthbound dudes have.  (Speaking of which--is there any reason
why lungs couldn't be built on a continuous flow model, evolutionarily?
Enquiring minds want to speculate!).

As a thought, it might be a lot easier for a gill-based being to
modify the surface area of its gills in times of great need than
it is for us lunger-types to take "deep breaths".  Some water
breathers have external gills (molluscs, I think?).  Designing
external gill extensions (extruded only under stress) might be
an interesting feature in a Merperson.

Are there any aquatic biologists reading this?  I'm sure there are
some real-world interesting strange adaptions that might be relevant.

David Kuijt
kuijt@asgard.umiacs.umd.edu

I'm a computer scientist, not an aquatic morphologist, so you can
ignore everything I've said here.  hehehehe