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The L p Neumann problem for the heat equation in non-cylindrical domains

Steve Hofmann, John L. Lewis (1998)

Journées équations aux dérivées partielles

I shall discuss joint work with John L. Lewis on the solvability of boundary value problems for the heat equation in non-cylindrical (i.e., time-varying) domains, whose boundaries are in some sense minimally smooth in both space and time. The emphasis will be on the Neumann problem with data in L p . A somewhat surprising feature of our results is that, in contrast to the cylindrical case, the optimal results hold when p = 2 , with the situation getting progressively worse as p approaches 1 . In particular,...

The linear-quadratic optimal control problem for delay differential equations

Gabriella Di Blasio (1981)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

In questo lavoro si considera il problema del controllo ottimo per un'equazione lineare con ritardo in uno spazio di Hilbert, con costo quadratico. Si dimostra che il problema della sintesi si traduce in una equazione di Riccati in uno opportuno spazio prodotto e si prova che tale equazione ammette un’unica soluzione.

The local solution of a parabolic-elliptic equation with a nonlinear Neumann boundary condition

Volker Pluschke, Frank Weber (1999)

Commentationes Mathematicae Universitatis Carolinae

We investigate a parabolic-elliptic problem, where the time derivative is multiplied by a coefficient which may vanish on time-dependent spatial subdomains. The linear equation is supplemented by a nonlinear Neumann boundary condition - u / ν A = g ( · , · , u ) with a locally defined, L r -bounded function g ( t , · , ξ ) . We prove the existence of a local weak solution to the problem by means of the Rothe method. A uniform a priori estimate for the Rothe approximations in L , which is required by the local assumptions on g , is derived by...

The logarithmic delay of KPP fronts in a periodic medium

François Hamel, James Nolen, Jean-Michel Roquejoffre, Lenya Ryzhik (2016)

Journal of the European Mathematical Society

We extend, to parabolic equations of the KPP type in periodic media, a result of Bramson which asserts that, in the case of a spatially homogeneous reaction rate, the time lag between the position of an initially compactly supported solution and that of a traveling wave grows logarithmically in time.

The method of Rothe and two-scale convergence in nonlinear problems

Jiří Vala (2003)

Applications of Mathematics

Modelling of macroscopic behaviour of materials, consisting of several layers or components, cannot avoid their microstructural properties. This article demonstrates how the method of Rothe, described in the book of K. Rektorys The Method of Discretization in Time, together with the two-scale homogenization technique can be applied to the existence and convergence analysis of some strongly nonlinear time-dependent problems of this type.

Currently displaying 61 – 80 of 187