Sökning: "coefficient inverse problem"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden coefficient inverse problem.

  1. 1. Efficient Adaptive Algorithms for an Electromagnetic Coefficient Inverse Problem

    Författare :John Bondestam Malmberg; Göteborgs universitet.; Gothenburg University.; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; coefficient inverse problem; inverse scattering; Maxwell’s equations; approximate global convergence; finite element method; adaptivity; a posteriori error analysis;

    Sammanfattning : This thesis comprises five scientific papers, all of which are focusing on the inverse problem of reconstructing a dielectric permittivity which may vary in space inside a given domain. The data for the reconstruction consist of time-domain observations of the electric field, resulting from a single incident wave, on a part of the boundary of the domain under consideration. LÄS MER

  2. 2. A Two-stage Numerical Procedure for an Inverse Scattering Problem

    Detta är en avhandling från Göteborg : University of Gothenburg

    Författare :John Bondestam Malmberg; Göteborgs universitet.; Gothenburg University.; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; coefficient inverse problem; inverse scattering; backscattering data; approximate global convergence; finite element method; adaptivity; a posteriori error analysis;

    Sammanfattning : In this thesis we study a numerical procedure for the solution of the inverse problem of reconstructing location, shape and material properties (in particular refractive indices) of scatterers located in a known background medium. The data consist of time-resolved backscattered radar signals from a single source position. LÄS MER

  3. 3. Inverse scattering and distribution of resonances on the real line

    Detta är en avhandling från Department of Mathematics, Lund University

    Författare :Michael Hitrik; Lund University.; Lunds universitet.; [1998]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; scattering poles; reflection coefficient; Schrödinger operator; inverse scattering; Matematik;

    Sammanfattning : We study aspects of scattering theory for the Schrödinger operator on the real line. In the first part of the thesis we consider potentials supported by a half-line, and we are interested in the inverse problem of reconstruction of the potential from the knowledge of values of the reflection coefficient at equidistributed points on the positive imaginary axis. LÄS MER

  4. 4. Computer-Assisted Proofs and Other Methods for Problems Regarding Nonlinear Differential Equations

    Detta är en avhandling från Uppsala : Department of Mathematics

    Författare :Oswald Fogelklou; Uppsala universitet.; [2012]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; computer-assisted proof; numerical verification; viscous Burgers’ equation; enclosure; existence; nonlinear boundary value problems; Euler equations; inverse problem; bicubic spline; interval analysis; heat equation; fluid limit; peer-to-peer networks; fixed points; stability; global stability; Mathematics; Matematik;

    Sammanfattning : This PhD thesis treats some problems concerning nonlinear differential equations.In the first two papers computer-assisted proofs are used. The differential equations there are rewritten as fixed point problems, and the existence of solutions are proved. LÄS MER

  5. 5. Robust Preconditioners Based on the Finite Element Framework

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Erik Bängtsson; Uppsala universitet.; Uppsala universitet.; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; FEM; iterative solution method; algebraic multilevel preconditioner; sparse approximate inverse; block preconditioner; Schur complement approximation; nonsymmetric saddle point matrix; isostatic glacial adjustment; pre-stress advection; elasticity; viscoelasticity; in compressible solid; ABAQUS; BEM DDM; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : Robust preconditioners on block-triangular and block-factorized form for three types of linear systems of two-by-two block form are studied in this thesis.The first type of linear systems, which are dense, arise from a boundary element type of discretization of crack propagation problems. LÄS MER