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CATEGORIES:CUED Control Group Seminars
SUMMARY:Energy Flow in Interconnected Systems - Professor 
 Jan Willems (K.U. Leuven)
DTSTART;TZID=Europe/London:20100205T140000
DTEND;TZID=Europe/London:20100205T150000
UID:TALK22708AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/22708
DESCRIPTION:We examine what is meant by the power and the ener
 gy which a physical system exchanges with its envi
 ronment. The systems which we consider interact th
 rough terminals\, as wires for electrical circuits
 \, and pins for mechanical devices. Associated wit
 h each terminal\, there are variables through whic
 h the system interacts with its environment. For c
 ircuits\, these variables are current and potentia
 l\, and for (one-dimensional) mechanical systems\,
  position and force. Systems are interconnected by
  sharing variables at the interconnected terminals
 . We define a port as a set of terminals that sati
 sfy certain conditions\, which we call the port-Ki
 rchhoff laws. For ports\, and only for ports\, we 
 define the power and the energy which flows into a
  system. Since a port involves more than one termi
 nal\, power and energy are not `local'\, but invol
 ve `action at a distance'. Moreover\, we cannot sp
 eak about the power and the energy flow along any 
 set of terminals. We discuss the nature of ports f
 or electrical and mechanical systems\, and derive 
 an expression for energy that is not frame depende
 nt. We end by proving that a connected RLC circuit
  forms a 1-port. This implies that in open systems
  energy rarely flows between subsystems along the 
 interconnected interface. 
LOCATION: Cambridge University Engineering Department\, LR5
CONTACT:Dr Ioannis Lestas
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