Slashdot Mirror

An interesting set-up similar to the Morgantown system is in place at Heathrow Airport, in some ways a huge improvement over the Morgantown system too. It still has significant boarding stations to limited destinations, but you can travel at any time and even hauls luggage and other smaller bits of bulk cargo (like would be expected at an airport).

A video of this in normal operation on YouTube can be found here:

https://www.youtube.com/watch?v=OEu2B4WlC34

yes I was being slightly sarcastic calling the water clean its just its a bit of a con people see dead fish they think the waters polluted but if you keep the oxygen levels high the fish are ok and nobody questions how clean the water flowing out actually is.

I used to write software for plc's and scada systems.
this is the best project I worked on

http://www.earthtech.co.uk/generic/documents/Yanna wa_000.pdf

http://www.edie.net/Library/view_article.asp?id=22 24&channel=0

http://www.arup.com/DOWNLOADBANK/download25.pdf

I am impressed there is so much on it and no credit at all for the company I worked for.
we were given the plc software to debug and pick faults with I wrote a scada system which demonstrated the plant in action basins filling valves opening skimmers raising and lowering it was fun to do my colleage wrote a file to create feedback for the plc program to react to.
the cycle on a basin i think was 6-8 hours we naturally sped it up so you could see the whole process cycle in about 6 minutes.

We found so many problems through our testing we got to rewrite the problem code. didnt get to go to tailand thou
and as you can tell we didnt even get a mention in the documentation.

If I remember rightly the process was controlled by two slc5/04 allen bradley plc's basically if one failed the other took over.

Anyone got a design for the programer building? Giant Processor, etc...

no, but the architect is Sir Norman Foster of Foster and Partners, responsible for the Millenium Footbridge in London that had to be closed after it was found to be dangerous... ...I'll follow you over...

The feet are very involved in the control of balance, as the designers of the Millennium Bridge (a walking bridge over the Thames in London) found out. The feet are much more sensitive to horizontal movement, in fact, than they are to vertical movement. People respond subconsciously to lateral movement of the foot with a restoring force: If a foot is moved a trivial amount to the right, say, the body makes an unconscious movement to return to its original position by pushing the foot to the right (to move the body back to the left). (The evolutionary importance of this fast reaction to slipping is clear.) Since this restoring force is in the same direction as the original movement, amplification can result. As any engineer can tell you, a source of amplification can be a source of oscillation if a resonant structure is available; if the body is on a suspension bridge, a natural resonance of the bridge can be excited. Further, once the bridge begins to sway laterally, people find it most comfortable to walk in phase with the swaying, in a manner that also amplifies the swaying.

The Millennium Bridge was completely stable under conventional dynamic analysis; with a small number people walking on it, or with a large number of people merely standing on it, it was also stable. However, with a large number of people (80,000-100,000) walking on it, as happened on opening day, "unexpected movements occurred." resulting in its temporary closure until modifications (in the form of resonance damping) were made. As described by the designers,

Chance footfall correlation, combined with the synchronisation that occurs naturally within a crowd, may cause the bridge to start to sway horizontally. If the sway is perceptible, a further effect can start to take hold. It becomes more comfortable for the pedestrians to walk in synchronization with the swaying of the bridge. The pedestrians find this makes their interaction with the movement of the bridge more predictable and helps them maintain their lateral balance. This instinctive behaviour ensures that the footfall forces are applied at the resonant frequency of the bridge and with a phase such as to increase the motion of the bridge. As the amplitude of the motion increases, the lateral force imparted by individuals increases, as does the degree of correlation between individuals.

Additional information on the phenomenon of synchronous lateral excitation of bridges is available here.

The feet are very involved in the control of balance, as the designers of the Millennium Bridge (a walking bridge over the Thames in London) found out. The feet are much more sensitive to horizontal movement, in fact, than they are to vertical movement. People respond subconsciously to lateral movement of the foot with a restoring force: If a foot is moved a trivial amount to the right, say, the body makes an unconscious movement to return to its original position by pushing the foot to the right (to move the body back to the left). (The evolutionary importance of this fast reaction to slipping is clear.) Since this restoring force is in the same direction as the original movement, amplification can result. As any engineer can tell you, a source of amplification can be a source of oscillation if a resonant structure is available; if the body is on a suspension bridge, a natural resonance of the bridge can be excited. Further, once the bridge begins to sway laterally, people find it most comfortable to walk in phase with the swaying, in a manner that also amplifies the swaying.

The Millennium Bridge was completely stable under conventional dynamic analysis; with a small number people walking on it, or with a large number of people merely standing on it, it was also stable. However, with a large number of people (80,000-100,000) walking on it, as happened on opening day, "unexpected movements occurred." resulting in its temporary closure until modifications (in the form of resonance damping) were made. As described by the designers,

Chance footfall correlation, combined with the synchronisation that occurs naturally within a crowd, may cause the bridge to start to sway horizontally. If the sway is perceptible, a further effect can start to take hold. It becomes more comfortable for the pedestrians to walk in synchronization with the swaying of the bridge. The pedestrians find this makes their interaction with the movement of the bridge more predictable and helps them maintain their lateral balance. This instinctive behaviour ensures that the footfall forces are applied at the resonant frequency of the bridge and with a phase such as to increase the motion of the bridge. As the amplitude of the motion increases, the lateral force imparted by individuals increases, as does the degree of correlation between individuals.

Additional information on the phenomenon of synchronous lateral excitation of bridges is available here.

The feet are very involved in the control of balance, as the designers of the Millennium Bridge (a walking bridge over the Thames in London) found out. The feet are much more sensitive to horizontal movement, in fact, than they are to vertical movement. People respond subconsciously to lateral movement of the foot with a restoring force: If a foot is moved a trivial amount to the right, say, the body makes an unconscious movement to return to its original position by pushing the foot to the right (to move the body back to the left). (The evolutionary importance of this fast reaction to slipping is clear.) Since this restoring force is in the same direction as the original movement, amplification can result. As any engineer can tell you, a source of amplification can be a source of oscillation if a resonant structure is available; if the body is on a suspension bridge, a natural resonance of the bridge can be excited. Further, once the bridge begins to sway laterally, people find it most comfortable to walk in phase with the swaying, in a manner that also amplifies the swaying.

The Millennium Bridge was completely stable under conventional dynamic analysis; with a small number people walking on it, or with a large number of people merely standing on it, it was also stable. However, with a large number of people (80,000-100,000) walking on it, as happened on opening day, "unexpected movements occurred." resulting in its temporary closure until modifications (in the form of resonance damping) were made. As described by the designers,

Chance footfall correlation, combined with the synchronisation that occurs naturally within a crowd, may cause the bridge to start to sway horizontally. If the sway is perceptible, a further effect can start to take hold. It becomes more comfortable for the pedestrians to walk in synchronization with the swaying of the bridge. The pedestrians find this makes their interaction with the movement of the bridge more predictable and helps them maintain their lateral balance. This instinctive behaviour ensures that the footfall forces are applied at the resonant frequency of the bridge and with a phase such as to increase the motion of the bridge. As the amplitude of the motion increases, the lateral force imparted by individuals increases, as does the degree of correlation between individuals.

Additional information on the phenomenon of synchronous lateral excitation of bridges is available here.

The feet are very involved in the control of balance, as the designers of the Millennium Bridge (a walking bridge over the Thames in London) found out. The feet are much more sensitive to horizontal movement, in fact, than they are to vertical movement. People respond subconsciously to lateral movement of the foot with a restoring force: If a foot is moved a trivial amount to the right, say, the body makes an unconscious movement to return to its original position by pushing the foot to the right (to move the body back to the left). (The evolutionary importance of this fast reaction to slipping is clear.) Since this restoring force is in the same direction as the original movement, amplification can result. As any engineer can tell you, a source of amplification can be a source of oscillation if a resonant structure is available; if the body is on a suspension bridge, a natural resonance of the bridge can be excited. Further, once the bridge begins to sway laterally, people find it most comfortable to walk in phase with the swaying, in a manner that also amplifies the swaying.

The Millennium Bridge was completely stable under conventional dynamic analysis; with a small number people walking on it, or with a large number of people merely standing on it, it was also stable. However, with a large number of people (80,000-100,000) walking on it, as happened on opening day, "unexpected movements occurred." resulting in its temporary closure until modifications (in the form of resonance damping) were made. As described by the designers,

Chance footfall correlation, combined with the synchronisation that occurs naturally within a crowd, may cause the bridge to start to sway horizontally. If the sway is perceptible, a further effect can start to take hold. It becomes more comfortable for the pedestrians to walk in synchronization with the swaying of the bridge. The pedestrians find this makes their interaction with the movement of the bridge more predictable and helps them maintain their lateral balance. This instinctive behaviour ensures that the footfall forces are applied at the resonant frequency of the bridge and with a phase such as to increase the motion of the bridge. As the amplitude of the motion increases, the lateral force imparted by individuals increases, as does the degree of correlation between individuals.

Additional information on the phenomenon of synchronous lateral excitation of bridges is available here.

In 1940, the Tacoma Narrows Bridge collapsed" because insufficient stiffening allowed the wind to create oscillations that destroyed it.

Fast forward 61 years to London and the Millennium Bridge near-disaster where insufficient stiffening ... well, you get the picture.

Point is, a list such as this one is valuable ONLY if we remember and learn from it. Those who forget history are doomed ...

Tell that to Arup, Foster, and Caro. Although it didn't collapse, the so-called Millenium Bridge which they were responsible for over the Thames in London had to be closed to the public a day or so after being declared open because it swayed too much. That was in the middle of last year, and as far as I know it's still closed. Apparently one of its resonances was near enough to a multiple of average walking pace to cause trouble, and once the swaying started, people's reactions tended to syncronise their movements to the bridge's. They're talking about fitting expensive dampers - but perhaps a few retired army officers would do as well:

"Break step, you horrible little people! Break step, I say!"

There's more information about it all here.