06 - Questions - Peter KLOEDEN

Monsieur Pierre-Yves Hénin, Président de l'Université Paris 1, acceuille des participants à la conférence et se félicite que le Centre Pierre Mendès-France serve de cadre à cette manifestation scientifique. Bande son disponible au format mp3 Durée : 6 mn

Monsieur Cuong Le Van, Directeur du Centre d'Economie de la Sorbonne, présente ce centre en décrivant plus particulièrement les thématiques de recherche en mathématiques qui y sont développées. Bande son disponible au format mp3 Durée : 4 mn

Consider the stochastic wave equation in dimension , , where denotes the formal derivative of a Gaussian stationary random field, white in time and correlated in space. Using Malliavin calculus, with Quer-Sardanyons we proved the existence and regularity of density of the law of the solution to the SPDE for any fixed . Denote this density by . More recently, with R. Dalang, we have established joint Hölder continuity in of the sample paths of the solution . On the basis of these two results, we can go further with the study of the properties in of the function , for any fixed . Using a method developed by Watanabe and applied to SPDEs in papers by Morien and Millet and Morien, we prove joint Hölder continuity of of the same order than the sample paths of the solution. We shall explain why the strong degeneracy of the fundamental solution leads to less regularity than one could have expected. Marta SANZ-SOLE. Universitat de Barcelona. Document associé : support de présentation : http://epi.univ-paris1.fr/servlet/com.univ.collaboratif.utils.LectureFichiergw?CODE_FICHIER=1182789806745 (pdf) Bande son disponible au format mp3 Durée : 55 mn

Marta SANZ-SOLE. Universitat de Barcelona. Bande son disponible au format mp3 Durée : 4 mn

The long term behaviour of dissipatively synchronized deterministic systems is determined by the system with the averaged vector field of the original uncoupled systems. This effect is preserved in the presence of environmental i.e., background or additive noise provided stochastic stationary solutions are used instead of steady state solutions. Random dynamical systems and random attractors provide the appropriate mathematical framework for such problems and require Ito stochastic differential equations to be transformed into pathwise random ordinary differential equations. An application to a system of semi-linear parabolic stochastic partial differential equations with additive space-time noise on the union of thin bounded tubular domains separated by a permeable membrane will be considered. What happens with linear multiplicative noise will also be considered. This a joint work with Tomas Caraballo (Sevilla) and Igor Chueshov (Kharkov). Based on the papers T. Caraballo and P.E. Kloeden, The persistence synchronization under environmental noise. Proc. Roy. Soc. London. A461 (2005), 2257-2267. T. Caraballo, I. Chueshov and P.E. Kloeden, Synchronization of a stochastic reaction-diffusion system on a thin two-layer domain. SIAM J. Math. Anal. (to appear) Peter KLOEDEN. Johann Wolfgang Goethe University. Bande son disponible au format mp3 Durée : 39 mn

Peter KLOEDEN. Johann Wolfgang Goethe University. Bande son disponible au format mp3 Durée : 4 mn

We want to present some results on gradient systems with convex potential in finite and infinite dimension. The techniques are based on recent developments in the theory of gradient flows in the Wasserstein metric. (joint work with L. Ambrosio & G. Savaré). Lorenzo ZAMBOTTI. Université Paris 6. Document associé : support de présentation : http://epi.univ-paris1.fr/servlet/com.univ.collaboratif.utils.LectureFichiergw?CODE_FICHIER=1182789954236 (pdf) Bande son disponible au format mp3 Durée : 43 mn

Lorenzo ZAMBOTTI. Université Paris 6. Bande son disponible au format mp3 Durée : 4 mn

As a model for multiscale systems under random influences on physical boundary, a stochastic partial differential equation under a fast random dynamical boundary condition is investigated. An effective equation is derived and justified by reducing the random dynamical boundary condition to a usual random boundary condition. The effective system is still a stochastic partial differential equation, but is more tractable. Furthermore, the quantitative comparison between the solution of the original stochastic system and the effective solution is provided by estimating deviations. Jinqiao DUAN. Illinois Institute of Technology. Document associé : support de présentation : http://epi.univ-paris1.fr/servlet/com.univ.collaboratif.utils.LectureFichiergw?CODE_FICHIER=1182790011791 (pdf) Bande son disponible au format mp3 Durée : 42 mn

Jinqiao DUAN. Illinois Institute of Technology. Bande son disponible au format mp3 Durée : 4 mn