| Topic: |
Science > Physics |
| User: |
"Edward Green" |
| Date: |
03 Jun 2005 06:21:34 PM |
| Object: |
A strange attractor? |
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
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| User: "" |
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| Title: Re: A strange attractor? |
03 Jun 2005 07:09:11 PM |
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Edward Green <spamspamspam3@netzero.com> wrote:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Its governed by the same laws that make toast always land jelly
side down when dropped over a shag carpet.
--
Jim Pennino
Remove .spam.sux to reply.
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| User: "The Ghost In The Machine" |
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| Title: Re: A strange attractor? |
03 Jun 2005 10:00:12 PM |
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In sci.physics,
<>
wrote
on Sat, 4 Jun 2005 00:09:11 +0000 (UTC)
<d7qrf7$an4$5@mail.specsol.com>:
Edward Green <spamspamspam3@netzero.com> wrote:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Its governed by the same laws that make toast always land jelly
side down when dropped over a shag carpet.
Even when tied to a cat? :-)
--
#191,
It's still legal to go .sigless.
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| User: "" |
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| Title: Re: A strange attractor? |
04 Jun 2005 02:17:53 AM |
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In article <vkf7n2-8m7.ln1@sirius.athghost7038suus.net>, The Ghost In The Machine <ewill@sirius.athghost7038suus.net> writes:
In sci.physics,
<>
wrote
on Sat, 4 Jun 2005 00:09:11 +0000 (UTC)
<d7qrf7$an4$5@mail.specsol.com>:
Edward Green <spamspamspam3@netzero.com> wrote:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Its governed by the same laws that make toast always land jelly
side down when dropped over a shag carpet.
Even when tied to a cat? :-)
That goes under antigravity devices.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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| User: "Bob Cain" |
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| Title: Re: A strange attractor? |
23 Jun 2005 01:07:45 AM |
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Edward Green wrote:
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
This is actually an example of the Very Weak Anthropic
Principle. If it were not making an annoying noise you
wouldn't be there to observe it. :-)
Bob
--
"Things should be described as simply as possible, but no
simpler."
A. Einstein
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| User: "Gregory L. Hansen" |
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| Title: Re: A strange attractor? |
03 Jun 2005 08:46:13 PM |
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In article <1117840894.132038.228840@g44g2000cwa.googlegroups.com>,
Edward Green <spamspamspam3@netzero.com> wrote:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
That's governed by Gumperson's law: The probability of anything happening
is in inverse ratio to its desirability.
--
"The average person, during a single day, deposits in his or her underwear
an amount of fecal bacteria equal to the weight of a quarter of a peanut."
-- Dr. Robert Buckman, Human Wildlife, p119.
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| User: "" |
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| Title: Re: A strange attractor? |
03 Jun 2005 06:32:52 PM |
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In article <1117840894.132038.228840@g44g2000cwa.googlegroups.com>, "Edward Green" <spamspamspam3@netzero.com> writes:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Murphy's law, I gather. Basically, in the presence of humans the
standard Lagrangian, L = T - V, is modified by the inclusion of an
additional term, i.e. L' = T - V - N, where N is "nuissance
potential". This biases all natural processes in the direction of
maximal nuissance.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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| User: "Edward Green" |
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| Title: Re: A strange attractor? |
04 Jun 2005 08:49:23 PM |
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wrote:
In article <1117840894.132038.228840@g44g2000cwa.googlegroups.com>, "Edward Green" <spamspamspam3@netzero.com> writes:
... there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Murphy's law, I gather. Basically, in the presence of humans the
standard Lagrangian, L = T - V, is modified by the inclusion of an
additional term, i.e. L' = T - V - N, where N is "nuissance
potential". This biases all natural processes in the direction of
maximal nuissance.
:-)))
I was actually very seriously considering your answer for a moment. ;-)
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| User: "" |
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| Title: Re: A strange attractor? |
05 Jun 2005 03:53:24 AM |
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In article <1117936163.470975.187210@f14g2000cwb.googlegroups.com>, "Edward Green" <spamspamspam3@netzero.com> writes:
mmeron@cars3.uchicago.edu wrote:
In article <1117840894.132038.228840@g44g2000cwa.googlegroups.com>, "Edward Green" <spamspamspam3@netzero.com> writes:
... there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Murphy's law, I gather. Basically, in the presence of humans the
standard Lagrangian, L = T - V, is modified by the inclusion of an
additional term, i.e. L' = T - V - N, where N is "nuissance
potential". This biases all natural processes in the direction of
maximal nuissance.
:-)))
I was actually very seriously considering your answer for a moment. ;-)
Well, I noticed few other ones in the same vein. I'm sure that you'll
find any experimentalist swearing that all processes naturally
gravitate to the state of maximal nuissance. Theorists may differ.
But then, they never have to deal with Mother Nature, just with their
models of her.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
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| User: "Boris Mohar" |
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| Title: Re: A strange attractor? |
03 Jun 2005 06:52:55 PM |
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On 3 Jun 2005 16:21:34 -0700, "Edward Green" <spamspamspam3@netzero.com>
wrote:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
I don't know but for a while I meant to post something of a same content. I
have noticed similar behavior with various motorized contraptions around that
house. My humidifier squeaks. It sops after i give it a kick. My fireplace
wood stove insert rattles because I am forcing air between its double walls.
Just about anything that can vibrate will settle in a resonate mode. It is
most stable configuration no matter how annoying it is.
--
Boris Mohar
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| User: "Edward Green" |
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| Title: Re: A strange attractor? |
05 Jun 2005 08:25:39 PM |
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Boris Mohar wrote:
I don't know but for a while I meant to post something of a same content. I
have noticed similar behavior with various motorized contraptions around that
house. My humidifier squeaks. It sops after i give it a kick. My fireplace
wood stove insert rattles because I am forcing air between its double walls.
Just about anything that can vibrate will settle in a resonate mode. It is
most stable configuration no matter how annoying it is.
Thanks for confirming my anecdote anecdotally. I have this feeling
many systems settle into a maximum noise mode, stop temporarily when
kicked, then return to what they were doing. I suppose they need some
degree of freedom to execute this annoyance.
There must be some general lesson in here striving to get out. Do
driven systems settle into modes of maximum energy dissipation? Why?
Maximum entropy creation rate? Why? Is there a second order second
law of thermodynamics? Not only do systems evolve to maximize entropy,
given the chance, they evolve to maximize the rate of creation of
entropy? Not only are there more ways for a system to exist in a higher
entropy state, there are more ways for a system to generate entropy
more quickly?
Probably if we recognize steady state open systems as a kind of higher
order stasis, such a higher order second law falls out naturally.
Or I have tapped into a fresh new fecund vein of BS. ;-)
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| User: "Sbharris[atsign]ix.netcom.com" |
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| Title: Re: A strange attractor? |
05 Jun 2005 09:05:56 PM |
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There must be some general lesson in here striving to get out. Do
driven systems settle into modes of maximum energy dissipation? Why?
Maximum entropy creation rate? Why? Is there a second order second
law of thermodynamics? Not only do systems evolve to maximize entropy,
given the chance, they evolve to maximize the rate of creation of
entropy? Not only are there more ways for a system to exist in a higher
entropy state, there are more ways for a system to generate entropy
more quickly? <<
COMMENT
These maximally-fast entropy-generating systems which self-evolve in a
non-equilibrium system through which energy is running, and in which
things are free to mechanically move around and adjust themselves to
entropy transport, are called "dissipative structures" by Prigogine.
Prigogine got the Nobel prize I think because everyone was under the
impression that he's mathematically explained the evolution of these
things. But I don't think he did. There's some controversy about
whether or not Prigogine's theories explain (in a fundamental
mathematical sense) any real-world phenomenon that chemists or
physicists before him, couldn't. Sure enough, these things form, as you
noticed! But alas, I don't think anybody to this day knows generally
WHY they do. So you're onto a deep mystery, all right.
I don't know what kind of esteam Prigogine is still held in, among
thermodynamicists. If any. Cognoscenti say his name with two hard g's,
if that's any help at cocktail parties where the origin of
irreversitiliby is being debated.
http://cscs.umich.edu/~crshalizi/notebooks/prigogine.html
SBH
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| User: "tadchem" |
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| Title: Re: A strange attractor? |
07 Jun 2005 09:02:03 AM |
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Sbharris[atsign]ix.netcom.com wrote:
<snip>
I don't know what kind of esteam Prigogine is still held in, among
thermodynamicists. If any. Cognoscenti say his name with two hard g's,
The 'cognoscenti' are poseurs.
I met him in the fall of 1976 at the University of Texas at Austin. He
himself pronounced the first 'g' hard, and the second soft -
"prig-oh-zheen".
if that's any help at cocktail parties where the origin of
irreversitiliby is being debated.
"Irreversitiliby?" I presume you meant "irreversibility."
http://order.ph.utexas.edu/people/Prigogine.htm
Tom Davidson
Richmond, VA
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| User: "Edward Green" |
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| Title: Re: A strange attractor? |
06 Jun 2005 05:27:19 PM |
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Sbharris[atsign]ix.netcom.com wrote:
These maximally-fast entropy-generating systems which self-evolve in a
non-equilibrium system through which energy is running, and in which
things are free to mechanically move around and adjust themselves to
entropy transport, are called "dissipative structures" by Prigogine.
Prigogine got the Nobel prize I think because everyone was under the
impression that he's mathematically explained the evolution of these
things.
:-)))
That's a priceless sentence. :-)
But I don't think he did. There's some controversy about
whether or not Prigogine's theories explain (in a fundamental
mathematical sense) any real-world phenomenon that chemists or
physicists before him, couldn't. Sure enough, these things form, as you
noticed! But alas, I don't think anybody to this day knows generally
WHY they do. So you're onto a deep mystery, all right.
Well, now that it's OK for me to express doubt, I did wonder just how
much that paper you referenced explained. But then, as we know, I
don't understand it, so I have to give them the benefit of the doubt.
(Hmm... I wonder it that's actually a realistic precept. There will
always be arcane things one does not follow, and a certain percentage
of these one will have to judge bunk/non-bunk on probability. And
that's how Sokol was born).
I think they assert they have reproduced the migration of the bead to
points of resonant tuning ... but if the "force" I questioned in my
other post is really defined to drive the system up the "kinetic energy
gradient", that would be a necessary result, wouldn't it? In other
words, if you know the end state, and define a "force" to get you
there, you will necessarily reach the expected end state.
Perhaps the answer could be as simple(?) as that the resonant
configurations are actually max entropy configurations under the
driving constraints -- forget "second order entropy -- i.e. , after one
is convinced that plain old entropy can be sufficiently well defined
for an open system. IOW, given any point in phase space near the
resonance, there would be many more ways for the system to fall into it
than to fall out of it -- the usual entropic story.
In fact, in very broad terms, that must be true. How else could the
system evolve? The open "non-equilibrium" constraints are merely
unusual from the point of view of elementary thermo. Nature doesn't
know if we've only formalized elementary thermo, though. She merely is
going to go for maximum probability under the constraints.
I don't know what kind of esteam Prigogine is still held in, among
thermodynamicists. If any. Cognoscenti say his name with two hard g's,
if that's any help at cocktail parties where the origin of
irreversitiliby is being debated.
Thanks. Now I am saved from that gaffe, should the occasion ever
arise. :-)
http://cscs.umich.edu/~crshalizi/notebooks/prigogine.html
SBH
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| User: "mountain man" |
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| Title: Re: A strange attractor? |
07 Jun 2005 03:47:13 AM |
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"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1118096839.941498.252340@z14g2000cwz.googlegroups.com...
Sbharris[atsign]ix.netcom.com wrote:
These maximally-fast entropy-generating systems which self-evolve in a
non-equilibrium system through which energy is running, and in which
things are free to mechanically move around and adjust themselves to
entropy transport, are called "dissipative structures" by Prigogine.
Prigogine got the Nobel prize I think because everyone was under the
impression that he's mathematically explained the evolution of these
things.
:-)))
That's a priceless sentence. :-)
Is that the same as valueless?
But I don't think he did.
http://www.mountainman.com.au/chaos_02.htm
--
Pete Brown
Falls Creek
OZ
www.mountainman.com.au
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| User: "Edward Green" |
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| Title: Re: A strange attractor? |
07 Jun 2005 05:27:23 PM |
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mountain man wrote:
"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1118096839.941498.252340@z14g2000cwz.googlegroups.com...
Sbharris[atsign]ix.netcom.com wrote:
Prigogine got the Nobel prize I think because everyone was under the
impression that he's mathematically explained the evolution of these
things.
:-)))
That's a priceless sentence. :-)
Is that the same as valueless?
I suppose when you shop in a "Payless Shoestore" you will expect free
shoes? :-)
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| User: "mountain man" |
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| Title: Re: A strange attractor? |
09 Jun 2005 08:52:03 PM |
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"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1118183243.677995.24000@f14g2000cwb.googlegroups.com...
mountain man wrote:
"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1118096839.941498.252340@z14g2000cwz.googlegroups.com...
Sbharris[atsign]ix.netcom.com wrote:
Prigogine got the Nobel prize I think because everyone was under the
impression that he's mathematically explained the evolution of these
things.
:-)))
That's a priceless sentence. :-)
Is that the same as valueless?
I suppose when you shop in a "Payless Shoestore" you will expect free
shoes? :-)
I like to go about barefooted Mr Ed, and have
not set foot in a shoe store for 20 years. Neither
do I watch the monkey box. So my expectations
are probably simpler than yours in regard to footware.
OTOH, the Nobel Prize is not
exactly a pair of shoes. Or is it?
Be good. Or good at it.
--
Pete Brown
Falls Creek
OZ
www.mountainman.com.au
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| User: "Ken S. Tucker" |
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| Title: Re: A strange attractor? |
07 Jun 2005 01:07:34 PM |
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Edward Green wrote:
Sbharris[atsign]ix.netcom.com wrote:
These maximally-fast entropy-generating systems which self-evolve in a
non-equilibrium system through which energy is running, and in which
things are free to mechanically move around and adjust themselves to
entropy transport, are called "dissipative structures" by Prigogine.
Prigogine got the Nobel prize I think because everyone was under the
impression that he's mathematically explained the evolution of these
things.
:-)))
That's a priceless sentence. :-)
But I don't think he did. There's some controversy about
whether or not Prigogine's theories explain (in a fundamental
mathematical sense) any real-world phenomenon that chemists or
physicists before him, couldn't. Sure enough, these things form, as you
noticed! But alas, I don't think anybody to this day knows generally
WHY they do. So you're onto a deep mystery, all right.
Well, now that it's OK for me to express doubt, I did wonder just how
much that paper you referenced explained. But then, as we know, I
don't understand it, so I have to give them the benefit of the doubt.
(Hmm... I wonder it that's actually a realistic precept. There will
always be arcane things one does not follow, and a certain percentage
of these one will have to judge bunk/non-bunk on probability. And
that's how Sokol was born).
I think they assert they have reproduced the migration of the bead to
points of resonant tuning ... but if the "force" I questioned in my
other post is really defined to drive the system up the "kinetic energy
gradient", that would be a necessary result, wouldn't it? In other
words, if you know the end state, and define a "force" to get you
there, you will necessarily reach the expected end state.
Perhaps the answer could be as simple(?) as that the resonant
configurations are actually max entropy configurations under the
driving constraints -- forget "second order entropy -- i.e. , after one
is convinced that plain old entropy can be sufficiently well defined
for an open system. IOW, given any point in phase space near the
resonance, there would be many more ways for the system to fall into it
than to fall out of it -- the usual entropic story.
In fact, in very broad terms, that must be true. How else could the
system evolve? The open "non-equilibrium" constraints are merely
unusual from the point of view of elementary thermo. Nature doesn't
know if we've only formalized elementary thermo, though. She merely is
going to go for maximum probability under the constraints.
I don't know what kind of esteam Prigogine is still held in, among
thermodynamicists. If any. Cognoscenti say his name with two hard g's,
if that's any help at cocktail parties where the origin of
irreversitiliby is being debated.
Thanks. Now I am saved from that gaffe, should the occasion ever
arise. :-)
http://cscs.umich.edu/~crshalizi/notebooks/prigogine.html
SBH
Edward! We need more data, I suggest experiments.
How about a paper weight (rock) of nearly equal
weight to the air-pump placed on the shelf to
change the reasonation characteristics. If the
rock and pump tend to one another, stay the same
or move away that might be interesting.
Ken
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| User: "Edward Green" |
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| Title: Re: A strange attractor? |
05 Jun 2005 08:26:06 PM |
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Boris Mohar wrote:
I don't know but for a while I meant to post something of a same content. I
have noticed similar behavior with various motorized contraptions around that
house. My humidifier squeaks. It sops after i give it a kick. My fireplace
wood stove insert rattles because I am forcing air between its double walls.
Just about anything that can vibrate will settle in a resonate mode. It is
most stable configuration no matter how annoying it is.
Thanks for confirming my anecdote anecdotally. I have this feeling
many systems settle into a maximum noise mode, stop temporarily when
kicked, then return to what they were doing. I suppose they need some
degree of freedom to execute this annoyance.
There must be some general lesson in here striving to get out. Do
driven systems settle into modes of maximum energy dissipation? Why?
Maximum entropy creation rate? Why? Is there a second order second
law of thermodynamics? Not only do systems evolve to maximize entropy,
given the chance, they evolve to maximize the rate of creation of
entropy? Not only are there more ways for a system to exist in a higher
entropy state, there are more ways for a system to generate entropy
more quickly?
Probably if we recognize steady state open systems as a kind of higher
order stasis, such a higher order second law falls out naturally.
Or I have tapped into a fresh new fecund vein of BS. ;-)
.
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| User: "Jan Panteltje" |
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| Title: Re: A strange attractor? |
04 Jun 2005 05:59:03 AM |
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On a sunny day (3 Jun 2005 16:21:34 -0700) it happened "Edward Green"
<spamspamspam3@netzero.com> wrote in
<1117840894.132038.228840@g44g2000cwa.googlegroups.com>:
A vibratory air pump rests on a wooden shelf about my aquarium.
After some period of unattended operation, the airpump, with near
certainty, has migrated to a position on the shelf where it makes a
loud vibratory noise. Giving the pump a random knock returns it, with
near certainty, to a position on the shelf where it makes a soft
vibratory noise.
I tentatively model that there are many more positions for the pump
which are quiet than which are loud (random positioning produces a
quiet outcome), where as there is something trapping and possibly
attractive about the positions which radiate more acoustic energy.
Why?
Point of highest exictation, has the biggest movement..
Least friction.
If it moves (not 100% flat surface) it wil move towards the point of
maximum exitation (less and less friction), moving away from it is more
and more difficult (more and more friction).
This right?
.
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| User: "Sbharris[atsign]ix.netcom.com" |
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| Title: Re: A strange attractor? |
04 Jun 2005 05:51:04 PM |
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Point of highest exictation, has the biggest movement..
Least friction.
If it moves (not 100% flat surface) it wil move towards the point of
maximum exitation (less and less friction), moving away from it is more
and more difficult (more and more friction).
This right?
================
Crap, I forgot friction!!!!
Very good observation.
With all the physics gurus on this forum we've not seen much from them.
The problem is that this isn't one of those problems that come
pre-packaged and digested in some text that all the grad student
studied. It actually requires some new and creative thought.
SBH
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| User: "Sbharris[atsign]ix.netcom.com" |
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| Title: Re: A strange attractor? |
03 Jun 2005 09:49:36 PM |
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You've found your own self-adaptive vibration system!
Let me take a qualitative stab. Surely there are many positions on the
board where the natural frequency of the pump finds that it has hit an
anti-node for a board vibration mode which has that same frequency
(given the pump placement at that spot). Obviously if such spots exist
and the pump finds them, excitation frequency will equal natural board
vibration frequency, and you'll have a resonance. As such, vibration
here will produce maximal amplitude of the vibration for the board, and
you'll get maximal noise.
Now, picture the pump at the antinode of such a mode. All spots from
there tend toward nodes where the wood is moving less up and down. It
seems to me that the pump will be drawn to nodes, not antinodes. But I
think a pump in such a position cannot excite vibration. So there's got
to be some intermediate position which maximizes both vibrational
amplitude and the pump's ability to exite the vibration. Where is that?
Halfway between node and antinode?
This kind of stuff is not obvious. But I did find one paper which
suggests that in the real world, systems react in such a way that the
masses free to move on a vibrating string do so until they reach a
point that their natural vibration frequencies match that of the
"forcing" frequency, which in this case is obviously your pump
frequency. Self-excitation is thus described, exactly as you've
described it. Except that YOUR forcing mechanism is (in a way) the
sliding bead itself.
http://www.lps.ens.fr/recherche/formes/papers/SelfAdapEPJB.pdf
SBH
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| User: "Edward Green" |
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| Title: Re: A strange attractor? |
05 Jun 2005 09:02:05 PM |
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Sbharris[atsign]ix.netcom.com wrote:
You've found your own self-adaptive vibration system!
<...>
This kind of stuff is not obvious. But I did find one paper which
How did you find this? It's a bullseye.
suggests that in the real world, systems react in such a way that the
masses free to move on a vibrating string do so until they reach a
point that their natural vibration frequencies match that of the
"forcing" frequency, which in this case is obviously your pump
frequency. Self-excitation is thus described, exactly as you've
described it. Except that YOUR forcing mechanism is (in a way) the
sliding bead itself.
http://www.lps.ens.fr/recherche/formes/papers/SelfAdapEPJB.pdf
I got stuck immediately between eqs. (2) and (3) on p. 162
The say that by the work energy theorem
G de = dK
where G is the force acting on the bead, de the bead displacment, dK
the change in kinetic energy.
OK that's great, but _which_ kinetic energy? Do they mean the average
over one cycle of the string, or do they mean the instantaneous value?
I'm thinking -- out on a BS limb here -- that in eq. (3) they have in
mind some kind of ensemble average: they are statistical physicists,
after all. Otherwise the 'gradient of the kinetic energy' doesn't make
much sense, does it! KE isn't a unique function of position.
What do you think?
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| User: "Sbharris[atsign]ix.netcom.com" |
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| Title: Re: A strange attractor? |
05 Jun 2005 09:13:01 PM |
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I have to admit I have no clue.
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| User: "Y.Porat" |
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| Title: Re: A strange attractor? |
07 Jun 2005 11:16:15 PM |
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have you ever opened your washing macine
and look ed inside??
it includes springs and mass blokes
not accidentally
it is acurately desighned and can be calculated!
may be the machine desighners actually use some
trial and error practice in a ddition to calculations
the resonance frequency of any object
id dependant on the ration of
m/k
while m is its mass and k is a force displacement
factor.
all the best
Y.Porat
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| User: "Maleki" |
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| Title: Re: A strange attractor? |
09 Jun 2005 10:43:08 AM |
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On 7 Jun 2005 21:16:15 -0700, Y.Porat wrote:
have you ever opened your washing macine
and look ed inside??
it includes springs and mass blokes
not accidentally
it is acurately desighned and can be calculated!
Look inside a portable one! :-) Way more work, about
two times more expensive too.
--
"sharAbe moft rA ghAzi ham mikhorad."
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