The single layer heat potential operator, K, arises in the solution of initial-boundary value problems for the heat equation using boundary integral methods. In this note we show that K maps a certain anisotropic Sobolev space isomorphically onto its dual, and, moreover, satisfies the coercivity inequality $ < K_{q,q} >\geq c\|q\|^2$. We thereby establish the well-posedness of the operator equation $K_q=f$ and provide a basis for the analysis of the discretizations.

A large class of elliptic boundary value problems in elasticity and fluid mechanics can be reduced to systems of boundary integral equations of the first kind. This paper summarizes some of the basic concepts and results concerning the mathematical foundation of boundary element methods for treating such a class of boundary integral equations.

We review some iterative methods for solving boundary integral equations which arise in Dirichlet and Neumann problems for the Helmholtz and Laplace equations. In particular we show how these integral equations may be transformed so that they may be solved by Neumann-Poincare Picard iteration.

In this talk, we discuss the solvability of the operator equation SX-XT=Q, where S and -T are generators of some semigroups of operators.

In this paper, a technique of coupling variational formulation of FEM and BIE (boundary integral equation) is used to deal with stationary Navier-Stokes equations in an unbounded domain. We discuss well-posedness for the coupling variational problem, the regularization method and FEM-BEM approximation. Finally, operator splitting and optimal control techniques are used to treat the difficulty of nonlinearity and constraints in computer implementation.

In this paper, we consider a boundary integral equation of second kind rising from potential theory. The equation may be solved numerically by Galerkin's method using piecewise constant functions. Because of the singularities produced by the corners, we have to grade the mesh near the corner. In general, Chandler obtained the order 2 superconvergence of the iterated Galerkin solution in the uniform norm. It is proved in this paper that the Richardson extrapolation increases the accuracy from order 2 to order 4.  

We give a brief account of recent results from a project to develop efficient algorithms and practical computer implementations for modeling complex, 3-D geological regions, with applications to exploration and general seismology. The problem is divided into geometrical and material description and visualization, forward modeling with ray tracing and finite element elastic wave propagation, and finally, least squares inversion of travel time data.  

The operators radiative transfer equation constructed by Chandrasekhar has been extended to the non-stationary case by Bellman and Wang. The local existence of solution of such non-stationary equation is established based on the construction of scattering matrices from a co-propagation group with unbounded generator. In case the system is dissipative, the local existence will extend to the global existence.

In this contribution, we report on some results recently obtained in joint work with Maksymilian Dryja. We first study an additive variant of Schwarz' alternating algorithm and establish that a fast method of this kind can be devised which is optimal in the sense that the number of conjugate gradient iterations required, to reach a certain tolerance, is independent of the mesh size as well as the number of subregions.

Preconditionings have proved to be a powerful technique for accelerating the rate of convergence of an iterative method. This paper, which is concerned with the conjugate gradient algorithm for large matrix computations, investigates an approximate polynomial preconditioning strategy. The method is particularly attractive for implementation on vector computers.

This paper gives an asymptotic expansion of the error on the mesh point for Galerkin approximation of integral equations of the first kind. The extrapolation formula and some numerical results are given.