Sökning: "Weak Convergence"

Visar resultat 1 - 5 av 61 avhandlingar innehållade orden Weak Convergence.

1. 1. 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

3. 2. Homogenization of Partial Differential Equations using Multiscale Convergence Methods

   Författare :Pernilla Johnsen; Liselott Flodén; Anders Holmbom; Marianne Olsson Lindberg; Jens Persson; Niklas Wellander; Mittuniversitetet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; homogenization theory; two-scale convergence; multiscale convergence; very weak multiscale convergence; evolution multiscale convergence; very weak evolution multiscale convergence; linear parabolic problems; linear hyperbolic-parabolic problems;

   Sammanfattning : The focus of this thesis is the theory of periodic homogenization of partial differential equations and some applicable concepts of convergence. More precisely, we study parabolic problems exhibiting both spatial and temporal microscopic oscillations and a vanishing volumetric heat capacity type of coefficient. LÄS MER

4. 3. On weak and strong convergence of numerical approximations of stochastic partial differential equations

   Författare :Fredrik Lindgren; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Additive noise; Cahn-Hilliard-Cook equation; Error estimate; Finite element; Hyperbolic equation; Parabolic equation; Rational approximation; Stochastic partial differential equation; Strong convergence; Truncation; Wiener process; Weak convergence; Weak convergence;

   Sammanfattning : This thesis is concerned with numerical approximation of linear stochastic partial differential equations driven by additive noise. In the first part, we develop a framework for the analysis of weak convergence and within this framework we analyze the stochastic heat equation, the stochastic wave equation, and the linearized stochastic Cahn-Hilliard, or the linearized Cahn-Hilliard-Cook equation. LÄS MER

5. 4. Weak Convergence of First-Rare-Event Times for Semi-Markov Processes

   Författare :Myroslav Drozdenko; Dmitrii Silvestrov; Raimondo Manca; Mälardalens högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; weak convergence; first-rare-event times; semi-Markov processes; Mathematical statistics; Matematisk statistik; Matematik tillämpad matematik;

   Sammanfattning : I denna avhandling studerar vi nödvändiga och tillräckliga villkor för svag konvergens av första-sällan-händelsetider för semi-Markovska processer.I introduktionen ger vi nödvändiga grundläggande definitioner och beskrivningar av modeller som betraktas i avhandlingen, samt ger några exempel på situationer i vilka metoder av första-sällan-händelsetider kan vara lämpliga att använda. LÄS MER

7. 5. Two Problems on Existence and Approximation Related to the Boltzmann Equation

   Författare :Vladislav Panferov; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Boltzmann equation; Povzner type models; diffuse reflection; discrete-velocity models; existence for large data; weak compactness; consistency; convergence; diffuse reflection;

   Sammanfattning : In this thesis, two different types of problems related to the Boltzmann equation of kinetic theory are studied. The first part is devoted to establishing consistency and convergence for discrete-velocity models of the Boltzmann equation. For a new such model, introduced by the author jointly with A. LÄS MER