Variational principles in nonequilibrium thermodynamics.
The variational principles introduced by Onsager into nonequilibrium thermodynamics are discussed. Several new variational formulations of the linear laws are introduced including both a Hamiltonian and Lagrangian form. Also an Onsager-Machlup type variational description of fluctuations is shown to apply  at steady states even far from equilibrium.
D007700:Kinetics; D008433:Mathematics; D008954:Models, Biological; D013816:Thermodynamics