Swarming and Schooling. Awe Inspiring

[BaalChatzaf]

Please have a look at this lecture on synchronized behavior by Stephan Strogatz

See emergent behavior clear and plain.

Ba'al Chatzaf

[tjohnson]

Yes, I've seen videos of swarming before - remarkable. Its very interesting that you have many independent entities making up a separate entity - one that seems to have it's own separate characteristics.

[Dragonfly]

Interesting! I've always wanted to write simulations of such behavior, as I've always suspected that they can be emulated quite well by a few simple conditions. Unfortunately I have no good programming system on my computer now (I had on my old DOS computer, but unfortunately that no longer works on my new computer), and at the moment not the time to look for such a system and set it up.

[Selene]

Robert:

Very nice. I was most surprised by the bridge situation. Did they not know about these issues?

I remember that Roebling and his son had been aware of that problem which was why you had signs at the Brooklyn Bridge to "Break Step," because you would create, with that type of synchronous vibration, a bridge that would begin to match the wave. These "harmonics" could literally collapse the structure. Same rule applied to long processions and parades across The Great Bridge [http://www.amazon.com/Great-Bridge-Story-Building-Brooklyn/dp/067145711X?tag=dogpile-20]. Great book by the way.

Angers Bridge, also called the Basse-Chaîne Bridge, was a suspension bridge over the Maine River in Angers, France. It was designed by Joseph Chaley and Bordillon, and built between 1836 and 1839^[1]. The bridge collapsed on April 16, 1850, when 478 French soldiers marched across it in lockstep. The bridge spanned 102 m, with two wire cables carrying a 7.2 m wide deck. Its towers consisted of cast iron columns 5.47 m tall.^[1]

Collapse

Because the soldiers were marching together, they caused the bridge to vibrate and twist from side to side, dislodging an anchoring cable from its concrete mooring. Though a thunderstorm occurred during the collapse, engineering reports at the time indicated that the collapse was due to the soldiers instead of the storm. Some 226 soldiers died in the river below the bridge. The failure was attributed to a combination of dynamic load and corrosion of the anchors for the main cables.

http://en.wikipedia....i/Angers_Bridge

Adam

Edited March 1, 2010 by Selene

[anonrobt]

Robert:

Very nice. I was most surprised by the bridge situation. Did they not know about these issues?

I remember that Roebling and his son had been aware of that problem which was why you had signs at the Brooklyn Bridge to "Break Step," because you would create, with that type of synchronous vibration, a bridge that would begin to match the wave. These "harmonics" could literally collapse the structure. Same rule applied to long processions and parades across The Great Bridge [http://www.amazon.com/Great-Bridge-Story-Building-Brooklyn/dp/067145711X?tag=dogpile-20]. Great book by the way.

Angers Bridge, also called the Basse-Chaîne Bridge, was a suspension bridge over the Maine River in Angers, France. It was designed by Joseph Chaley and Bordillon, and built between 1836 and 1839^[1]. The bridge collapsed on April 16, 1850, when 478 French soldiers marched across it in lockstep. The bridge spanned 102 m, with two wire cables carrying a 7.2 m wide deck. Its towers consisted of cast iron columns 5.47 m tall.^[1]

Collapse

Because the soldiers were marching together, they caused the bridge to vibrate and twist from side to side, dislodging an anchoring cable from its concrete mooring. Though a thunderstorm occurred during the collapse, engineering reports at the time indicated that the collapse was due to the soldiers instead of the storm. Some 226 soldiers died in the river below the bridge. The failure was attributed to a combination of dynamic load and corrosion of the anchors for the main cables.

http://en.wikipedia....i/Angers_Bridge

Adam

That has been conjecture - but never proven... even Mythbusters couldn't prove the conjecture...

[Selene]

Anonrobt:

Out of curiosity, did that Cambridge dude's construction prove it to your standards?

Adam

[anonrobt]

Anonrobt:

Out of curiosity, did that Cambridge dude's construction prove it to your standards?

Adam

not really - I've been of mixed minds on this one, as 'common sense' seems to say yes, the marching will vibrate all to hell and pieces... but - there's too many things in the real world that, despite 'common sense', do not work in such a fashion, else everything would had fallen long ago... I think an issue of 'context' is involved that is being overlooked... or, maybe not - just not know...

[Mikee]

Please have a look at this lecture on synchronized behavior by Stephan Strogatz

See emergent behavior clear and plain.

Ba'al Chatzaf

Nice. Thanks for posting this. I've observed birds "swarming" many times, always gives me chills. I've watched large groups of birds of different species, different sizes, swarm together to chase a hawk from their territory. What explains that behavior? Different species cooperating for a common goal?

[Selene]

Please have a look at this lecture on synchronized behavior by Stephan Strogatz

http://www.ted.com/i...tz_on_sync.html

See emergent behavior clear and plain.

Ba'al Chatzaf

Nice. Thanks for posting this. I've observed birds "swarming" many times, always gives me chills. I've watched large groups of birds of different species, different sizes, swarm together to chase a hawk from their territory. What explains that behavior? Different species cooperating for a common goal?

Those birds were trained in NY City!

Bird fight