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On the eigenvalues of an elliptic operator a x , H u

Sergio Campanato (1992)

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

Let Ω be a bounded open convex set of class C 2 . Let a x , H u be a non linear operator satisfying the condition (A) (elliptic) with constants α , γ , δ . We prove that a number λ 0 is an eigenvalue for the operator a x , H u if and only if the number α λ is an eigen-value for the operator Δ u . If λ 0 , the two systems a x , H u = λ u and Δ u = α λ u have the same solutions. In particular, also the eventual eigen-values of the operator a x , H u should all be negative. Finally, we obtain a sufficient condition for the existence of solutions u H 2 H 0 1 Ω of the system...

On the existence of a generalized solution to a three-dimensional elliptic equation with radiation boundary condition

László Simon, Gisbert Stoyan (2001)

Applications of Mathematics

For a second order elliptic equation with a nonlinear radiation-type boundary condition on the surface of a three-dimensional domain, we prove existence of generalized solutions without explicit conditions (like u | Γ L 5 ( Γ ) ) on the trace of solutions. In the boundary condition, we admit polynomial growth of any fixed degree in the unknown solution, and the heat exchange and emissivity coefficients may vary along the radiating surface. Our generalized solution is contained in a Sobolev space with an exponent...

On the existence of infinitely many solutions for a class of semilinear elliptic equations in R N

Francesca Alessio, Paolo Caldiroli, Piero Montecchiari (1998)

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

We show, by variational methods, that there exists a set A open and dense in a L R N : a 0 such that if a A then the problem - u + u = a x u p - 1 u , u H 1 R N , with p subcritical (or more general nonlinearities), admits infinitely many solutions.

On the finite element analysis of problems with nonlinear Newton boundary conditions in nonpolygonal domains

Miloslav Feistauer, Karel Najzar, Veronika Sobotíková (2001)

Applications of Mathematics

The paper is concerned with the study of an elliptic boundary value problem with a nonlinear Newton boundary condition considered in a two-dimensional nonpolygonal domain with a curved boundary. The existence and uniqueness of the solution of the continuous problem is a consequence of the monotone operator theory. The main attention is paid to the effect of the basic finite element variational crimes: approximation of the curved boundary by a polygonal one and the evaluation of integrals by numerical...

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