On solution uniqueness of elliptic boundary value problems

In this paper, we consider the problem of solution uniqueness for the second order elliptic boundary value problem, by looking at its finite element or finite difference approximations. We derive several equivalent conditions, which are simpler and easier than the boundedness of the entries of the inverse matrix given in Yamamoto et al., [T. Yamamoto, S. Oishi, Q. Fang, Discretization principles for linear two-point boundary value problems, II, Numer. Funct. Anal. Optim. 29 (2008) 213–224]. The numerical experiments are provided to support the analysis made. Strictly speaking, the uniqueness of solution is equivalent to the existence of nonzero eigenvalues in the corresponding eigenvalue problem, and this condition should be checked by solving the corresponding eigenvalue problems. An application of the equivalent conditions is that we may discover the uniqueness simultaneously, while seeking the approximate solutions of elliptic boundary equations.     

Fredholm property of boundary value problems for a fourth-order elliptic differential-operator equation with operator boundary conditions

In a Hilbert space H, we study the Fredholm property of a boundary value problem for a fourth-order differential-operator equation of elliptic type with unbounded operators in the boundary conditions. We find sufficient conditions on the operators in the boundary conditions for the problem to be Fredholm. We give applications of the abstract results to boundary value problems for fourth-order elliptic partial differential equations in nonsmooth domains.     

An infinite-dimensional Evans function theory for elliptic boundary value problems

An infinite-dimensional Evans function E(λ) and a stability index theorem are developed for the elliptic eigenvalue problem in a bounded domain Ω⊂Rm. The number of zero points of the Evans function in a bounded, simply connected complex domain D is shown to be equal to the number of eigenvalues of the corresponding elliptic operator in D. When the domain Ω is star-shaped, an associated unstable bundle E(D) based on D is constructed, and the first Chern number of E(D) also gives the number of eigenvalues of the elliptic operator inside D.     

Fredholm property of elliptic boundary value problems for partial differential and differential- operator equations

In this paper we find conditions on boundary value problems for elliptic differential-operator equations of the 4-th order in an interval to be fredholm. Apparently, this is the first publication for elliptic differential-operator equations of the 4-th order, when the principal part of the equation has the form u′?n(t) + Au″(t) + Bu(t), where AB^-1/2 is a bounded operator and is not compact. As an application we find some algebraic conditions on boundary value problems for elliptic partial equations of the 4-th order in cylindrical domains to be fredholm. Note that a new method has actually been suggested here for investigation of boundary value problems for elliptic partial equations of the 4-th order.     

An a posteriori estimation for the solution of elliptic boundary value problems by means of upwind FEM

The paper presents a theory for a posteriori error estimationof finite element solutions of two-dimensional convection-diffusionequations which are discretized by means of an upwind method.The main theorem gives an error estimation in terms of approximatelycomputable and localized quantities.     

Maximum principles for functionals associated with the solution of semilinear elliptic boundary value problems

We consider a new P-function associated with the solutionu of an elliptic boundary value problem and obtain pointwise bounds for the gradient in terms of the maximum ofu and the geometry of the domain. SimilarP-functions have previously been used to obtain bounds of the same type. Our results give improved bounds for certain problems, in particular we obtain isoperimetric inequalities for the maximum stress in the Saint-Venant torsion problem.     

An efficient algorithm for solving fifth-order boundary value problems

In this paper, we apply the homotopy perturbation method for solving the fifth-order boundary value problems. The analytical results of the equations have been obtained in terms of convergent series with easily computable components. Several examples are given to illustrate the efficiency and implementation of the homotopy perturbation method. Comparisons are made to confirm the reliability of the method.     

Boundary value problems for a class of elliptic operator pencils

In this paper operator pencilsA(x, D, ) are studied which act on a manifold with boundary and satisfy the condition of N-ellipticity with parameter, a generalization of the notion of ellipticity with parameter as introduced by Agmon and Agranovich-Vishik. Sobolev spaces corresponding to the Newton polygon are defined and investigated; in particular it is possible to describe their trace spaces. With respect to these spaces, an a priori estimate is proved for the Dirichlet boundary value problem connected with an N-elliptic pencil.Supported in part by the Deutsche Forschungsgemeinschaft and by Russian Foundation of Fundamental Research, Grant 00-01-00387.     

Approximation of the bifurcation function for elliptic boundary value problems

The bifurcation function for an elliptic boundary value problem is a vector field B(ω) on R ^d whose zeros are in a one‐to‐one correspondence with the solutions of the boundary value problem. Finite element approximations of the boundary value problem are shown to give rise to an approximate bifurcation function B^h(ω), which is also a vector field on R ^d. Estimates of the difference B(ω) − B^h(ω) are derived, and methods for computing B^h(ω) are discussed. © 2000 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 16: 194–213, 2000     

An adaptive algorithm for solving stochastic multi-point boundary value problems

In this paper, we present an adaptive multiple-shooting method to solve stochastic multi-point boundary value problems. We first analyze the strong order of convergence of the underlying multiple shooting method. We then proceed to describe the proposed strategy to adaptively choose the location of shooting points. We analyze the effect of method parameters on the performance of the overall scheme using a benchmark linear two-point stochastic boundary value problem. We illustrate the effectiveness of this approach on several (one and two dimensional) test problems by comparing our results with other non-adaptive alternative techniques proposed in the literature.     

An analytic shooting-like approach for the solution of nonlinear boundary value problems

In this paper a novel approach is presented for an analytic approximate solution of nonlinear differential equations with boundary conditions. By converting the nonlinear problem into an initial value form, a shooting-like procedure is introduced based on the powerful homotopy analysis technique. The proposed methodology is shown to work adequately for solving single or multiple solutions of some sample nonlinear boundary value problems.     

Convergence of the multigrid -cycle algorithm for second-order boundary value problems without full elliptic regularity

The multigrid -cycle algorithm using the Richardson relaxation scheme as the smoother is studied in this paper. For second-order elliptic boundary value problems, the contraction number of the -cycle algorithm is shown to improve uniformly with the increase of the number of smoothing steps, without assuming full elliptic regularity. As a consequence, the -cycle convergence result of Braess and Hackbusch is generalized to problems without full elliptic regularity.

     

Regularity estimates for elliptic boundary value problems in Besov spaces

We consider the Dirichlet problem for Poisson's equation on a nonconvex plane polygonal domain . New regularity estimates for its solution in terms of Besov and Sobolev norms of fractional order are proved. The analysis is based on new interpolation results and multilevel representations of norms on Sobolev and Besov spaces. The results can be extended to a large class of elliptic boundary value problems. Some new sharp finite element error estimates are deduced.

     

An efficient iteration approach for nonlinear boundary value problems in 2D piezoelectric semiconductors

Based on initial nonlinear constitutive equations, we establish the extended displacement and traction boundary integral equations for a piezoelectric medium with a volume electric charge, along with electron and electric current density boundary integral equations for a conductor with a volume electric current. Then, an iterative approach is proposed for investigation of boundary value problems in two-dimensional piezoelectric semiconductors (PSCs). Compared with extended displacements obtained by finite element analysis, this approach is validated via a rectangular PSC under extended external loads. Furthermore, as a numerical example, extended displacements across an elliptical hole in a rectangular PSC are investigated. It is shown that there is a stress concentration near the elliptical hole, which is closely dependent on its shape.     

Solution to the boundary value problem for an arbitrary elliptic operator subject to a radiation condition

It is shown that the generalized Fourier transform can be extended to an arbitrary elliptic operator in a cylindrical domain with a Robin boundary condition. In this case, the existence of the Fourier image is a completely correct radiation condition determining a solution to the problem that is a superposition of waves traveling away from the source.