Cet exposé a pour but de présenter des résultats récents de l’auteur concernant les asymptotiques de Lifshitz pour des perturbations aléatoires d’opérateurs de Schrödinger périodiques. Certains de ces résultats ont été obtenus en collaboration avec T. Wolff.
A class of infinite-dimensional dissipative dynamical systems is defined for which there exists a unique equilibrium point, and the rate of convergence to this point of the trajectories of a dynamical system from the above class is exponential. All the trajectories of the system converge to this point as t → +∞, no matter what the initial conditions are. This class consists of strongly dissipative systems. An example of such systems is provided by passive systems in network theory (see, e.g., MR0601947...
We study axisymmetric solutions to the Navier-Stokes equations in the whole three-dimensional space. We find conditions on the radial and angular components of the velocity field which are sufficient for proving the regularity of weak solutions.