Мішана задача для нелінійного рівняння типу коливань балки п'ятого порядку в обмеженій області

Abstract

A nonlocal problem with general linear twopoint conditions for a strongly hyperbolic (wave) equation utt + a2Au, where a = a(t) > 0 is a continuously differentiable on [0,T] function, P A = ^2 d2/dx2 is the Laplace operator, is investigated in the domain, which is the Cartesian j=1 product of the closed interval [0,T] and the dimensional torus Qp. This problem is in general Hadamard ill-posed and connected with the small denominators problem. By the metric approach the theorem touching lower bounds of small denominators has been proved. On the base of such bounds the existence and uniqueness conditions of the problem solution in Sobolev spaces of periodical functions with respect to variables xi,... ,xp were obtained.