http://dissertations.ub.rug.nl/faculties/science/2010/r.v.polyuga/
It is devoted to a port-Hamiltonian system that seems to be a good
option to model a physical system. I should confess that I have met this
term for a first time and have not understood the background mathematics
yet. If someone knows a good introduction into port-Hamiltonian systems,
I would appreciate a reference/link.
Evgenii
http://blog.rudnyi.ru