Fourth order Birkhoff regular problems with eigenvalue parameter dependent boundary conditions

A regular fourth order differential equation which depends quadratically on the eigenvalue parameter $\lambda$ is considered with classes of separable boundary conditions independent of $\lambda$ or depending on $\lambda$ linearly. Conditions are given for the problems to be Birkhoff regular

Self-adjoint fourth order differential operators with eigenvalue parameter dependent boundary conditions

The eigenvalue problem y(4)(¸; x) ¡ (gy0)0(¸; x) = ¸2y(¸; x) with boundary conditions y(¸; 0) = 0; y00(¸; 0) = 0; y(¸; a) = 0; y00(¸; a) + i®¸y0(¸; a) = 0; where g 2 C1[0; a] is a real valued function and ® > 0, has an operator pencil L(¸) = ¸2 ¡ i®¸K ¡ A realization with self-adjoint operators A, M and K. It was shown that the spectrum for the above boundary eigenvalue problem is located in the upper-half plane and on the imaginary axis. This is due to the fact that A, M and K are self-adjoint. We consider the eigenvalue problem y(4)(¸; x) ¡ (gy0)0(¸; x) = ¸2y(¸; x) with more general ¸-dependent separated boundary conditions Bj(¸)y = 0 for j = 1; ¢ ¢ ¢ ; 4 where Bj(¸)y = y[pj ](aj) or Bj(¸)y = y[pj ](aj) + i²j®¸y[qj ](aj), aj = 0 for j = 1; 2 and aj = a for j = 3; 4, ® > 0, ²j = ¡1 or ²j = 1. We assume that at least one of the B1(¸)y = 0, B2(¸)y = 0, B3(¸)y = 0, B4(¸)y = 0 is of the form y[p](0)+i²®¸y[q](0) = 0 or y[p](a)+i²®¸y[q](a) = 0 and we investigate classes of boundary conditions for which the corresponding operator A is self-adjoint

Spectral theory of self-adjoint higher order differential operators with eigenvalue parameter dependent boundary conditions

We consider on the interval [0; a], rstly fourth-order di erential operators with eigenvalue parameter dependent boundary conditions and secondly a sixth-order di erential operator with eigenvalue parameter dependent boundary conditions. We associate to each of these problems a quadratic operator pencil with self-adjoint operators. We investigate the spectral proprieties of these problems, the location of the eigenvalues and we explicitly derive the rst four terms of the eigenvalue asymptotics

A new inertial condition on the subgradient extragradient method for solving pseudomonotone equilibrium problem

In this paper we study the pseudomonotone equilibrium problem. We consider a new inertial condition for the subgradient extragradient method with self-adaptive step size for approximating a solution of the equilibrium problem in a real Hilbert space. Our proposed method contains inertial factor with new conditions that only depend on the iteration coefficient. We obtain a weak convergence result of the proposed method under weaker conditions on the inertial factor than many existing conditions in the literature. Finally, we present some numerical experiments for our proposed method in comparison with existing methods in the literature. Our result improves, extends and generalizes several existing results in the literature

Analytic vs. numerical solutions to a Sturm-Liouville transmission eigenproblem

An elliptic one-dimensional second order boundary value problem involving discontinuous coefficients, with or without transmission conditions, is considered. For the former case by a direct sum spaces method we show that the eigenvalues are real, geometrically simple and the eigenfunctions are orthogonal. Then the eigenpairs are computed numerically by a local linear finite element method (FEM) and by some global spectral collocation methods. The spectral collocation is based on Chebyshev polynomials (ChC) for problems on bounded intervals respectively on Fourier system (FsC) for periodic problems. The numerical stability in computing eigenvalues is investigated by estimating their (relative) drift with respect to the order of approximation. The accuracy in computing the eigenvectors is addressed by estimating their departure from orthogonality as well as by the asymptotic order of convergence. The discontinuity of coefficients in the problems at hand reduces the exponential order of convergence, usual for any well designed spectral algorithm, to an algebraic one. As expected, the accuracy of ChC outcomes overpasses by far that of FEM outcomes

SELF-ADJOINT FOURTH ORDER DIFFERENTIAL OPERATORS WITH EIGENVALUE PARAMETER OPERATORS WITH EIGENVALUE PARAMETER

Click on the link to view the abstract.Keywords: Fourth order differential equation, eigenvalue dependent boundary conditions, quadratic operator pencil, self-adjoint operatorQuaestiones Mathematicae 34(2011), 393–40

SIXTH ORDER DIFFERENTIAL OPERATORS WITH EIGENVALUE DEPENDENT BOUNDARY CONDITIONS

We consider eigenvalue problems for sixth-order ordinary differential equations. Such differential equations occur in mathematical models of vibrations of curved arches. With suitably chosen eigenvalue dependent boundary conditions, the problem is realized by a quadratic operator pencil. It is shown that the operators in this pencil are self-adjoint, and that the spectrum of the pencil consists of eigenvalues of finite multiplicity in the closed upper halfplane, except for finitely many eigenvalues on the negative imaginary axis

Analytic vs. numerical solutions to a Sturm-Liouville transmission eigenproblem

An elliptic one-dimensional second order boundary value problem involving discontinuous coefficients, with or without transmission conditions, is considered. For the former case by a direct sum spaces method we show that the eigenvalues are real, geometrically simple and the eigenfunctions are orthogonal. Then the eigenpairs are computed numerically by a local linear finite element method (FEM) and by some global spectral collocation methods. The spectral collocation is based on Chebyshev polynomials (ChC) for problems on bounded intervals respectively on Fourier system (FsC) for periodic problems. The numerical stability in computing eigenvalues is investigated by estimating their (relative) drift with respect to the order of approximation. The accuracy in computing the eigenvectors is addressed by estimating their departure from orthogonality as well as by the asymptotic order of convergence. The discontinuity of coefficients in the problems at hand reduces the exponential order of convergence, usual for any well designed spectral algorithm, to an algebraic one. As expected, the accuracy of ChC outcomes overpasses by far that of FEM outcomes