Sökning: "MATHEMATICS Applied mathematics Numerical analysis"

Visar resultat 31 - 35 av 104 avhandlingar innehållade orden MATHEMATICS Applied mathematics Numerical analysis.

1. 31. Mathematical Modelling of Light Scattering in Paper and Print

   Författare :Per Edström; Mårten Gulliksson; Inge Söderkvist; Mittuniversitetet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mathematical modeling; radiative transfer; solution method; numerical stability; speed; light scattering; light absorption; Kubelka-Munk; errors; reflectance calculations; MATHEMATICS; MATEMATIK;

   Sammanfattning : A problem formulation and a solution method are outlined for the radiative transfer problem in vertically inhomogeneous scattering and absorbing media, using discrete ordinate model geometry. The treatment spans from the physical problem via a continuous formulation, a discretization and a numerical analysis, to an implementation with performance evaluation and application to real-world problems. LÄS MER

3. 32. Some Extensions of Poincaré-Bendixson Theory Applied to a Resonant Converter

   Författare :Jan Melin; Matematik LTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Datalogi; numerisk analys; system; kontroll; numerical analysis; systems; control; Naturvetenskap; Computer science; Natural science; Poincaré-Bendixson Theory; Limit Cycles; Resonant Converter; Distributions; Piecewise Linear Systems;

   Sammanfattning : In this thesis existence and uniqueness of limit cycles are shown for a resonant converter, by extending Poincaré-Bendixson theory to non-smooth vector fields. We discuss relevant control theory and the role of simulations... LÄS MER

4. 33. 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. 34. Numerical Methods for Darcy Flow Problems with Rough and Uncertain Data

   Författare :Fredrik Hellman; Axel Målqvist; Auli Niemi; Fritjof Fagerlund; Robert Scheichl; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; numerical homogenization; multiscale methods; rough coefficients; high contrast coefficients; mixed finite elements; cdf estimation; multilevel Monte Carlo methods; Darcy flow problems; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : We address two computational challenges for numerical simulations of Darcy flow problems: rough and uncertain data. The rapidly varying and possibly high contrast permeability coefficient for the pressure equation in Darcy flow problems generally leads to irregular solutions, which in turn make standard solution techniques perform poorly. LÄS MER

7. 35. Some recent developments of the homogenization theory with applications

   Författare :Leon Simula; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik;

   Sammanfattning : This thesis in applied mathematics is devoted to theoretical and some of the numerical aspects of the homogenization theory. The thesis consists of five papers. In the first paper we give a brief presentation of some basic ideas, which can serve as an introduction and frame to the author´s contributions to the papers in this thesis. LÄS MER