Search for dissertations about: "Eigenvalues problem."

Showing result 1 - 5 of 48 swedish dissertations containing the words Eigenvalues problem..

  2. 1. Some new results concerning general weighted regular Sturm-Liouville problems

    Author : Mervis Kikonko; Lars-Erik Persson; Peter Wall; Angelo B. Mingarelli; Alexey Karapetyants; Luleå tekniska universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Partial differential equations; Sturm-Liouville problem; Right-definite; left-definite; non-definite; indefinite; Dirichlet problem; spectrum; eigenvalues; non-real eigenvalues; Richardson number; Richardson index; turning point; Mathematics; Matematik;

    Abstract : In this PhD thesis we study some weighted regular Sturm-Liouville problems in which the weight function takes on both positive and negative signs in an appropriate interval [a,b]. With such  problems there is the possible existence of non-real eigenvalues, unlike in the definite case (i.e. READ MORE

  4. 2. Bound states and resonances in three-body system

    Author : Yarevsky Evgeny; Thomas N. Rescigno; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Three-body problem; Total angular momentum representation; Resonances; Complex Scaling Method; Finite Element Method; Eigenvalues problem.; Physics; fysik;

    Abstract : The quantum three-body problem plays an important role in different branches of the modern physics. In the nuclear, atomic and molecular physics there exist a number of systems whose behaviour is naturally described in this framework. READ MORE

  5. 3. The Dirac Equation: Numerical and Asymptotic Analysis

    Author : Hasan Almanasreh; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Dirac operator; eigenvalue problem; finite element method; spurious eigenvalues; Petrov-Galerkin; cubic Hermite basis functions; stability parameter; meshfree method; $hp$-cloud; intrinsic enrichment; G-convergence; $ Gamma$-convergence; scattering theory; identification; wave operator; stationary approach; Dirac operator;

    Abstract : The thesis consists of three parts, although each part belongs to a specific subject area in mathematics, they are considered as subfields of the perturbation theory. The main objective of the presented work is the study of the Dirac operator; the first part concerns the treatment of the spurious eigenvalues in the computation of the discrete spectrum. READ MORE

  6. 4. Resolvent Estimates and Bounds on Eigenvalues for Schrödinger and Dirac Operators

    Author : Alexandra Enblom; Vladimir Kozlov; Ari Laptev; David Krejcirik; Linköpings universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Spectral theory; Schrödinger operators; polyharmonic operators; Dirac operators; non-self-adjoint perturbations; complex potential; estimation of eigenvalues; Carleman inequalities; Hardy inequalities;

    Abstract : This thesis concerns the spectral theory of Schrödinger and Dirac operators. The main results relate to the problems of estimating perturbed eigenvalues. The thesis is based on four papers.The first paper focuses on the problem of localization of perturbed eigenvalues for multidimensional Schrödinger operators. READ MORE

  7. 5. Extremal eigenvalues and geometry of quantum graphs

    Author : Andrea Serio; Pavel Kurasov; Annemarie Luger; Evans Harrell; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; quantum graphs; spectral estimates; trace formula; Euler characteristic; Mathematics; matematik;

    Abstract : This thesis consists of four papers concerning topics in the spectral theory of quantum graphs, which are differential operators on metric graphs.In paper I we present a family of graphs with an arbitrary number of cycles for which a certain eigenvalue upper estimate is sharp. READ MORE