We apply functional analytical and variational methods in order to study well-posedness and qualitative properties of evolution equations on product Hilbert spaces. To this aim we introduce an algebraic formalism for matrices of sesquilinear mappings. We apply our results to parabolic problems of different nature: a coupled diffusive system arising in neurobiology, a strongly damped wave equati...

This paper develops a theory of singular arc, and the corresponding second order necessary and sufficient conditions, for the optimal control of a semilinear parabolic equation with scalar control applied on the r.h.s. We obtain in particular an extension of Kelley’s condition, and the characterization of a quadratic growth property for a weak norm.

A semilinear parabolic equation in a Banach space is considered. The purpose of this paper is to show the dependence of an error estimate for Rothe’s method on the regularity of initial data. The proofs are done using a semigroup theory and Taylor spectral representation.

An analysis of discretizations of the Helmholtz equation in L 2 and in negative norms (extended version) Flatness of semilinear parabolic PDEs-A generalized Chauchy-Kowalevski approach 27/2012 R. Donninger and B. Schörkhuber Stable blow up dynamics for energy supercritical wave equations 26/2012 P.

We consider the global attractor Af for the semiflow generated by a scalar semilinear parabolic equation of the form ut = uxx + f(u, ux), defined on the circle, x ∈ S. Using a characterization of the period maps for planar Hamiltonian systems of the form u′′ + g(u) = 0 we discuss questions related to the topological equivalence between global attractors.

In this paper, we consider a semilinear parabolic equation ut = ∆u + u q ∫ t 0 u(x, s)ds, x ∈ Ω, t > 0 with nonlocal nonlinear boundary condition u|∂Ω×(0,+∞) = ∫ Ω φ(x, y)u (y, t)dy and nonnegative initial data, where p, q ≥ 0 and l > 0. The blow-up criteria and the blow-up rate are obtained.

We study the wellposedness and pathwise regularity of semilinear non-autonomous parabolic evolution equations with boundary and interior noise in an Lp setting. We obtain existence and uniqueness of mild and weak solutions. The boundary noise term is reformulated as a perturbation of a stochastic evolution equation with values in extrapolation spaces.

In this paper, using theory of attractors for multi-valued semiflows and semiprocesses, we prove the existence of compact attractor for a semilinear degenerate parabolic equation involving the Grushin operator in which the conditions imposed on the nonlinearity provide the global existence of a weak solution, but not uniqueness. Mathematics Subject Classification: 35B41, 35K65, 35D05

An optimal control problem for semilinear parabolic partial differential equations is considered. The control variable appears in the leading term of the equation. Necessary conditions for optimal controls are established by the method of homogenizing spike variation. Results for problems with state constraints are also stated. Mathematics Subject Classification. 49K20, 35B27. Received August 7...