Sökning: "jens persson"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden jens persson.

  1. 1. Homogenization of Some Selected Elliptic and Parabolic Problems Employing Suitable Generalized Modes of Two-Scale Convergence

    Författare :Jens Persson; Anders Holmbom; Liselott Flodén; Marianne Lindberg; Mårten Gulliksson; Peter Wall; Mittuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; H-convergence; G-convergence; homogenization; multiscale analysis; two-scale convergence; multiscale convergence; elliptic partial differential equations; parabolic partial differential equations; monotone operators; heterogeneous media; non-periodic media; Mathematical analysis; Analys;

    Sammanfattning : The present thesis is devoted to the homogenization of certain elliptic and parabolic partial differential equations by means of appropriate generalizations of the notion of two-scale convergence. Since homogenization is defined in terms of H-convergence, we desire to find the H-limits of sequences of periodic monotone parabolic operators with two spatial scales and an arbitrary number of temporal scales and the H-limits of sequences of two-dimensional possibly non-periodic linear elliptic operators by utilizing the theories for evolution-multiscale convergence and λ-scale convergence, respectively, which are generalizations of the classical two-scale convergence mode and custom-made to treat homogenization problems of the prescribed kinds. LÄS MER

  3. 2. Selected Topics in Homogenization

    Författare :Jens Persson; Anders Holmbom; Liselott Flodén; Marianne Olsson Lindberg; Mårten Gulliksson; Peter Wall; Mittuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; homogenization theory; H-convergence; two-scale convergence; very weak two-scale convergence; multiscale convergence; very weak multiscale convergence; evolution-multiscale convergence; very weak evolution-multiscale convergence; λ-scale convergence; non-periodic linear elliptic problems; evolution-multiscale linear parabolic problems; evolution-multiscale monotone parabolic problems; detection of scales of heterogeneity;

    Sammanfattning : The main focus of the present thesis is on the homogenization of some selected elliptic and parabolic problems. More precisely, we homogenize: non-periodic linear elliptic problems in two dimensions exhibiting a homothetic scaling property; two types of evolution-multiscale linear parabolic problems, one having two spatial and two temporal microscopic scales where the latter ones are given in terms of a two-parameter family, and one having two spatial and three temporal microscopic scales that are fixed power functions; and, finally, evolution-multiscale monotone parabolic problems with one spatial and an arbitrary number of temporal microscopic scales that are not restricted to be given in terms of power functions. LÄS MER

  4. 3. On Tool Failure in Die Casting

    Författare :Anders Persson; Sture Hogmark; Jens Bergström; Torsten Eriksson; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; Materialvetenskap; Materials science; Teknisk materialvetenskap; materialvetenskap; Materials Science;

    Sammanfattning : Die casting is a very cost-efficient method of forming thin-walled and complex near net-shaped products with close geometric tolerances and good surface finish. A permanent die tool is used to make large quantities of identical products. The performance and tool life are limited by several mechanisms, e.g. LÄS MER

  5. 4. The development of resource polymorphism – Effects of diet, predation risk and population dynamical feedbacks

    Författare :Jens Andersson; Lennart Persson; André M. De Roos; Umeå universitet; []
    Nyckelord :body shape; diet; geometric morphometrics; phenotypic plasticity; population dynamics; predation risk; resource polymorphism; size structured populations;

    Sammanfattning : This thesis deals with the evolution of individuals within a species adapted to utilize specific resources, i.e. resource polymorphism. Although a well-known phenomenon, the understanding of the mechanisms behind is not complete. LÄS MER

  7. 5. Regulatory and Structural Properties of the High-Affinity Phosphate Acquisition System in Saccharomyces cerevisiae

    Författare :Jens Lagerstedt; Bengt L. Persson; Joseph W. DePierre; Peter J. Henderson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biochemistry; Biokemi;

    Sammanfattning : Inorganic phosphate is an essential nutrient required for the synthesis of many cellular components (e.g., nucleic acids, proteins, lipids and sugars), as well as for meeting metabolic needs (e.g. LÄS MER