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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 long-time behaviour of the solutions to semilinear stochastic partial differential equations on the whole space

Ralf Manthey (2001)

Mathematica Bohemica

The Cauchy problem for a stochastic partial differential equation with a spatial correlated Gaussian noise is considered. The "drift" is continuous, one-sided linearily bounded and of at most polynomial growth while the "diffusion" is globally Lipschitz continuous. In the paper statements on existence and uniqueness of solutions, their pathwise spatial growth and on their ultimate boundedness as well as on asymptotical exponential stability in mean square in a certain Hilbert space of weighted functions...

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