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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The absolute functional calculus for sectorial operators

Kucherenko, Tamara. January 2005 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 18, 2006) Vita. Includes bibliographical references.
2

Higher order commutators in the method of orbits

Unknown Date (has links)
Benson spaces of higher order are introduced extending the idea of N. Krugljak and M. Milman, A distance between orbits that controls commutator estimates and invertibilty of operators, Advances in Mathematics 182 (2004), 78-123. The concept of Benson shift operators is introduced and a class of spaces equipped with these operators is considered. Commutator theorems of higher order on orbit spaces generated by a single element are proved for this class. It is shown that these results apply to the complex method of interpolation and to the real method of interpolation for the case q=1. Two new characterizations are presented of the domain space of the "derivation" operator in the context of orbital methods. Comparisons to the work of others are made, especially the unifying paper of M. Cwikel, N. Kalton, M. Milman and R. Rochberg, A United Theory of Commutator Estimates for a Class of Interpolation Methods, Advances in Mathematics 169 2002, 241-312. / by Eva, Kasprikova / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.
3

An exploration of hole filling algorithms : a thesis /

Firestone, Eric. Wood, Zoë Justine. January 2008 (has links)
Thesis (M.S.)--California Polytechnic State University, 2008. / Major professor: Zoë Wood, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Computer Science." "June 2008." Includes bibliographical references (leaves 44-45). Also available online. Also available on microfiche (1 sheet).
4

Metodos de interpolação real e espaços de Sobolev e Besov sobre a esfera Sd / Real interpolation methods and Sobolev and Besov espaces on the Sd sphere

Oliveira, Andrielber da Silva 28 April 2006 (has links)
Orientador: Sergio Antonio Tozoni / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-06T13:07:08Z (GMT). No. of bitstreams: 1 Oliveira_AndrielberdaSilva_M.pdf: 1284065 bytes, checksum: 0117263cf98921db674e49f5f57d460d (MD5) Previous issue date: 2006 / Resumo: O objetivo da dissertação é realizar um estudo dos espaços de Besov sobre a esfera unitária d-dimensional real Sd. No primeiro capítulo são estudados espaços de interpolação utilizando dois métodos de interpolação real. Em particular são estudados os Teoremas de Equivalência e de Reiteração para os J-método e K-método. No segundo capítulo é realizado um estudo rápido sobre análise harmônica na esfera Sd, incluindo um estudo sobre harmônicos esféricos, harmônicos zonais, somas de Cesàro e sobre um teorema de multiplicadores. O terceiro e último capítulo é o mais importante e nele são aplicados os resultados dos capítulos anteriores. São introduzidos os espaços de Besov, decompondo uma função suave definida sobre a esfera d-dimensional, em uma série de harmônicos esféricos e usando uma seqüência de polinômios zonais que podem ser vistos como uma generalização natural dos polinômios de Vallée Poussin definidos sobre o círculo unitário. O principal resultado estudado diz que todo espaço de Besov pode ser obtido como espaço de interpolação de dois espaços de Sobolev / Abstract: The purpose of this work is to make a study about Besov¿s spaces on the unit d-dimensional real sphere Sd. In the first chapter are studied spaces of interpolation using two real interpolation methods. In particular, are studied The Equivalence Theorem and The Reiteration Theorem for the J-method and the K-method. In the second chapter it is made a short study about harmonic analysis on the sphere Sd, including a study about spherics harmonics, zonal harmonics, Cesàro sums and about a multiplier theorem. The third and last chapter is the most important of this work. In this chapter are applied the results of the others chapters. Are introduced the Besov spaces, decomposing a smooth function defined on the d-dimensional sphere, in a series of harmonics spherics and using a sequence o zonal polynomials which can be seen as a natural generalization of the Vallée Poussin polynomials defined on the unit circle. The main result studied says that every Besov¿s space can be got as a interpolation space of two Sobolev¿s spaces / Mestrado / Mestre em Matemática
5

On a Fokker–Planck equation coupled with a constraint

Huth, Robert 09 August 2012 (has links)
In dieser Arbeit untersuchen wir zwei Modelle, die das Laden und Entladen einer Lithium-Ionen Batterie beschreiben. Beide Modelle spiegeln eine Hysterese in dem Spannungs-Ladungs-Verlauf wider. Wir skizzieren den Modellierungsprozess von einem diskreten vielteilchen Modell sowie einem kontinuierlichen vielteilchen Modell. Das erste führt zu einer axiomatischen Beschreibung der Evolution makroskopischer Größen, während das zweite in eine nichtlineare Fokker-Planck Gleichung mündet. Wir zeigen die Existenz und Eindeutigkeit von Lösungen der nichtlinearen Fokker-Planck Gleichung und untersuchen deren qualitative Eigenschaften. Wir benutzen Interpolationsräume und Halbgruppen sektorieller Operatoren um den semilinearen Charakter der partiellen Differentialgleichung auszunutzen. Um globale Existenz zu erhalten, schätzen wir die Dissipation einer mit dem Modell verknüpften Energie ab. Diese Energie ist verwandt mit der L-log-L Norm, welche wir mithilfe einer Gagliardo-Nirenberg Ungleichung zu der L^2 Norm in Verbindung setzen können. Die notwendigen und hinreichenden Bedingungen zur globalen Existenz von Lösungen sind aus physikalischer Sicht plausibel. Der Ladezustand der Batterie muss innerhalb der Werte Voll und Leer sein. In numerischen Experimenten untersuchen wir das qualitative Verhalten von Lösungen. Wir zeigen die Konvergenz der numerischen Lösungen zu den exakten Lösungen. Dafür nutzen wir ähnliche Techniken wie bei der lokalen Existenztheorie. Wir beobachten die Tendenz von Lösungen sich um bestimmte Punkte zu konzentrieren. Unterstützt durch die formale Asymptotik zeigt dies für eine bestimmte Wahl von Parameter-Skalierungen, dass Lösungen gegen Dirac-Maße konvergieren. In diesem Grenzverhalten wird das System durch die Evolution von makroskopischen Größen beschrieben, welche wir auch in dem diskreten vielteilchen Modell wiederfinden. In diesen makroskopischen Größen lässt sich eine Hysterese beobachten. / We discuss two models which describe the charging and discharging of a lithium-ion battery and especially the hysteretical behaviour therein. We give an overview on the modelling process for a discrete many particle model and a continuous many particle model. The former results in an axiomatic description of macroscopic quantities while the latter gives a nonlinear Fokker-Planck equation. The nonlinear Fokker-Planck equation is analysed with respect to existence and uniqueness of solutions as well as qualitative behaviour of solutions. The nonlinearity in this partial differential equation stems from a coefficient which depends on the solution first non-local and second in a higher order. We use interpolation spaces and semigroups generated from sectorial operators to show the existence and uniqueness of solutions locally in time. The global existence in time relies on estimates for the dissipation of an energy. The suitable energy is related to the L-log-L norm and so a Gagliardo-Nirenberg inequality is needed to connect this back to L^2 estimates. It turns out that the conditions for global in time existence of solutions are physical reasonable. One needs that the loading state of the battery shall stay between totally empty and totally full. In numerical experiments we investigate the qualitative behaviour of solutions to the nonlinear Fokker-Planck equation. We are able to show convergence of the numerical solutions to the exact solution. We observe that solutions tend to concentrate at certain points. Supported by results from formal asymptotic expansions, we document the limiting behaviour in a certain scaling of the appearing parameters, which is the formation of Dirac measures. The evolution of the global quantities, which we observe in numerical simulations, is the same as what results from the discrete many particle model and one observes hysteretic behaviour in macroscopic quantities.
6

Équation de diffusion généralisée pour un modèle de croissance et de dispersion d'une population incluant des comportements individuels à la frontière des divers habitats / Generalized diffusion equation for a growth and dispersion model of a population including individual behaviors on the boundary of the different habitats

Thorel, Alexandre 24 May 2018 (has links)
Le but de ce travail est l'étude d'un problème de transmission en dynamique de population entre deux habitats juxtaposés. Dans chacun des habitats, on considère une équation aux dérivées partielles, modélisant la dispersion généralisée, formée par une combinaison linéaire du laplacien et du bilaplacien. On commence d'abord par étudier et résoudre la même équation avec diverses conditions aux limites posée dans un seul habitat. Cette étude est effectuée grâce à une formulation opérationnelle du problème: on réécrit cette EDP sous forme d'équation différentielle, posée dans un espace de Banach construit sur les espaces Lp avec 1 < p < +∞, où les coefficients sont des opérateurs linéaires non bornés. Grâce au calcul fonctionnel, à la théorie des semi-groupes analytiques et à la théorie de l'interpolation, on obtient des résultats optimaux d'existence, d'unicité et de régularité maximale de la solution classique si et seulement si les données sont dans certains espaces d'interpolation. / The aim of this work is the study of a transmission problem in population dynamics between two juxtaposed habitats. In each habitat, we consider a partial differential equation, modeling the generalized dispersion, made up of a linear combination of Laplacian and Bilaplacian operators. We begin by studying and solving the same equation with various boundary conditions in a single habitat. This study is carried out using an operational formulation of the problem: we rewrite this PDE as a differential equation, set in a Banach space built on the spaces Lp with 1 < p < +∞, where the coefficients are unbounded linear operators. Thanks to functional calculus, analytic semigroup theory and interpolation theory, we obtain optimal results of existence, uniqueness and maximum regularity of the classical solution if and only if the data are in some interpolation spaces.

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