20,100 research outputs found
An integral equation method for solving neumann problems on simply and multiply connected regions with smooth boundaries
This research presents several new boundary integral equations for the solution of Laplace’s equation with the Neumann boundary condition on both bounded and unbounded multiply connected regions. The integral equations are uniquely solvable Fredholm integral equations of the second kind with the generalized Neumann kernel. The complete discussion of the solvability of the integral equations is also presented. Numerical results obtained show the efficiency of the proposed method when the boundaries of the regions are sufficiently smooth
Interface crack between dissimilar one-dimensional hexagonal quasicrystals with piezoelectric effect
A fast and well-conditioned spectral method for singular integral equations
We develop a spectral method for solving univariate singular integral
equations over unions of intervals by utilizing Chebyshev and ultraspherical
polynomials to reformulate the equations as almost-banded infinite-dimensional
systems. This is accomplished by utilizing low rank approximations for sparse
representations of the bivariate kernels. The resulting system can be solved in
operations using an adaptive QR factorization, where is
the bandwidth and is the optimal number of unknowns needed to resolve the
true solution. The complexity is reduced to operations by
pre-caching the QR factorization when the same operator is used for multiple
right-hand sides. Stability is proved by showing that the resulting linear
operator can be diagonally preconditioned to be a compact perturbation of the
identity. Applications considered include the Faraday cage, and acoustic
scattering for the Helmholtz and gravity Helmholtz equations, including
spectrally accurate numerical evaluation of the far- and near-field solution.
The Julia software package SingularIntegralEquations.jl implements our method
with a convenient, user-friendly interface
Dynamical Systems Method for solving ill-conditioned linear algebraic systems
A new method, the Dynamical Systems Method (DSM), justified recently, is
applied to solving ill-conditioned linear algebraic system (ICLAS). The DSM
gives a new approach to solving a wide class of ill-posed problems. In this
paper a new iterative scheme for solving ICLAS is proposed. This iterative
scheme is based on the DSM solution. An a posteriori stopping rules for the
proposed method is justified. This paper also gives an a posteriori stopping
rule for a modified iterative scheme developed in A.G.Ramm, JMAA,330
(2007),1338-1346, and proves convergence of the solution obtained by the
iterative scheme.Comment: 26 page
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