Comparative Study of the Adiabatic Evolution of a Nonlinear Damped   Oscillator and an Hamiltonian Generalized Nonlinear Oscillator
  In this paper we study to what extent the canonical equivalence and the identity of the geometric phases of dissipative and conservative linear oscillators, established in a preceeding paper, can be generalized to nonlinear ones. Considering first the 1-D quartic generalized oscillator we determine, by means of a perturbative time dependent technic of reduction to normal forms, the canonical transformations which lead to the adiabatic invariant of the system and to the first order non linear correction to its Hannay angle. Then, applying the same transformations to the 1-D quartic damped oscillator we show that this oscillator is canonically equivalent to the linear generalized harmonic oscillator for finite values of the damping parameter (which implies no correction to the linear Hannay angle) whereas, in an appropriate weak damping limit, it becomes equivalent to the quartic generalized oscillator (which implies a non linear correction to this angle) . 
O.V. Usatenko, J.-P. Provost, G. Vallee and A. Boudine