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Visar resultat 1 - 5 av 6 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Symmetries and conservation laws

    Författare :Raisa Khamitova; Börje Nilsson; Claes Jougréus; Maria Luz Gandarias; Växjö universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; conservation law; Noether s theorem; Lie group analysis; Lie-Bäcklund transformations; basis of conservation laws; formal Lagrangian; self-adjoint equation; quasi-selfadjoint; equation; nonlocal conservation law; Mathematical physics; Matematisk fysik;

    Sammanfattning : Conservation laws play an important role in science. The aim of this thesis is to provide an overview and develop new methods for constructing conservation laws using Lie group theory. The derivation of conservation laws for invariant variational problems is based on Noether’s theorem. LÄS MER

  3. 2. Simulation of Chemical Reactors

    Författare :Tommy Hertzberg; Avdelningen för kemiteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; fluid flow; chemical reactors; formox; fractional step; catalytic combustion; Spectral methods; self-adjoint operator; Chemical technology and engineering; Kemiteknik och kemisk teknologi;

    Sammanfattning : This thesis consists basically of two parts. They are, however, interrelated by the fact that both parts concerns modelling of catalytic reaction systems and also by the fact that in both parts, spectral methods are used for simulation. The first part describes the numerical treatment of the dispersion model. LÄS MER

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

    Författare :Hasan Almanasreh; Göteborgs universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  5. 4. Homogenization of elliptic equations in thin cylinders and related qualitative problems

    Författare :Iryna Pankratova; Nils Svanstedt; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik;

    Sammanfattning : The thesis consists of four closely related papers (A, B, C and D). Paper A concerns the study of the behaviour at infinity of solutions to second order elliptic equation with first order terms stated in a half-cylinder. LÄS MER

  7. 5. Higher order differential operators on graphs

    Författare :Jacob Muller; Pavel Kurasov; Ram Band; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Almost periodic functions; differential operators on metric graphs; quantum graphs; estimation of eigenvalues;

    Sammanfattning : This thesis consists of two papers, enumerated by Roman numerals. The main focus is on the spectral theory of -Laplacians. Here, an -Laplacian, for integer , refers to a metric graph equipped with a differential operator whose differential expression is the -th derivative. LÄS MER