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SUMMARY:Energy Flow in Interconnected Systems - Professor Jan Willems (K.U
 . Leuven)
DTSTART:20100205T140000Z
DTEND:20100205T150000Z
UID:TALK22708@talks.cam.ac.uk
CONTACT:Dr Ioannis Lestas
DESCRIPTION:We examine what is meant by the power and the energy which a p
 hysical system exchanges with its environment. The systems which we consid
 er interact through terminals\, as wires for electrical circuits\, and pin
 s for mechanical devices. Associated with each terminal\, there are variab
 les through which the system interacts with its environment. For circuits\
 , these variables are current and potential\, and for (one-dimensional) me
 chanical systems\, position and force. Systems are interconnected by shari
 ng variables at the interconnected terminals. We define a port as a set of
  terminals that satisfy certain conditions\, which we call the port-Kirchh
 off laws. For ports\, and only for ports\, we define the power and the ene
 rgy which flows into a system. Since a port involves more than one termina
 l\, power and energy are not `local'\, but involve `action at a distance'.
  Moreover\, we cannot speak about the power and the energy flow along any 
 set of terminals. We discuss the nature of ports for electrical and mechan
 ical systems\, and derive an expression for energy that is not frame depen
 dent. 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
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