Abstract
The first part of this thesis (articles 1 and 2) is devoted to the study of the asymptotic behavior of solutions of second order dynamical systems with vanishing dissipation. The second part of this thesis (articles 3 to 6) is devoted to the study of some proximal-type algorithms. We prove that these algorithms converge towards solutions of some minimization problems. In each case, an application is given in the area of domain decomposition for PDE's.