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On an oblique derivative problem involving an indefinite weight

M. Faierman (1994)

Archivum Mathematicum

In this paper we derive results concerning the angular distrubition of the eigenvalues and the completeness of the principal vectors in certain function spaces for an oblique derivative problem involving an indefinite weight function for a second order elliptic operator defined in a bounded region.

On an ODE Relevant for the General Theory of the Hyperbolic Cauchy Problem

Bernardi, Enrico, Bove, Antonio (2008)

Serdica Mathematical Journal

2000 Mathematics Subject Classification: 34E20, 35L80, 35L15.In this paper we study an ODE in the complex plane. This is a key step in the search of new necessary conditions for the well posedness of the Cauchy Problem for hyperbolic operators with double characteristics.

On an optimal control problem for a quasilinear parabolic equation

S. Farag, M. Farag (2000)

Applicationes Mathematicae

An optimal control problem governed by a quasilinear parabolic equation with additional constraints is investigated. The optimal control problem is converted to an optimization problem which is solved using a penalty function technique. The existence and uniqueness theorems are investigated. The derivation of formulae for the gradient of the modified function is explainedby solving the adjoint problem.

On an over-determined problem of free boundary of a degenerate parabolic equation

Jiaqing Pan (2013)

Applications of Mathematics

This work is concerned with the inverse problem of determining initial value of the Cauchy problem for a nonlinear diffusion process with an additional condition on free boundary. Considering the flow of water through a homogeneous isotropic rigid porous medium, we have such desire: for every given positive constants K and T 0 , to decide the initial value u 0 such that the solution u ( x , t ) satisfies sup x H u ( T 0 ) | x | K , where H u ( T 0 ) = { x N : u ( x , T 0 ) > 0 } . In this paper, we first establish a priori estimate u t C ( t ) u and a more precise Poincaré type inequality...

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