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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.
231

Problemas variacionais de fronteira livre com duas fases e resultados do tipo PhragmÃn-Lindelof regidos por equaÃÃes elÃpticas nÃo lineares singulares/degeneradas / Variational problems with free boundary of two phases and results of PhragmÃn-Lindelof type governed by natural nonlinear elliptic equations/degenerate / Problemas variacionais de fronteira livre com duas fases e resultados do tipo PhragmÃn-Lindelof regidos por equaÃÃes elÃpticas nÃo lineares singulares/degeneradas / Variational problems with free boundary of two phases and results of PhragmÃn-Lindelof type governed by natural nonlinear elliptic equations/degenerate

Josà Ederson Melo Braga 06 June 2015 (has links)
Neste trabalho de tese discutimos resultados recentes sobre a regularidade e propriedades geomÃtricas de soluÃÃes variacionais de problemas de fronteira livre de duas fases regidos por equaÃÃes elÃpticas nÃo lineares degeneradas/singulares. Discutimos tambÃm resultados do tipo PhragmÃm-Lindelof para tais equaÃÃes classificando essas soluÃÃes em semi-espaÃos. / Neste trabalho de tese discutimos resultados recentes sobre a regularidade e propriedades geomÃtricas de soluÃÃes variacionais de problemas de fronteira livre de duas fases regidos por equaÃÃes elÃpticas nÃo lineares degeneradas/singulares. Discutimos tambÃm resultados do tipo PhragmÃm-Lindelof para tais equaÃÃes classificando essas soluÃÃes em semi-espaÃos. / In this work of thesis we discuss recents results on the regularity and geometric properties of variational solutions of two phase free boundary problems governed by singular/degenerate nonlinear elliptic equations. We also discuss PhragmÃn-Lindelof type results for such equations classifying those solutions in half spaces. / In this work of thesis we discuss recents results on the regularity and geometric properties of variational solutions of two phase free boundary problems governed by singular/degenerate nonlinear elliptic equations. We also discuss PhragmÃn-Lindelof type results for such equations classifying those solutions in half spaces.
232

Singularidades analíticas reais e complexas / Real and complex analytic singularities

Laís da Silva Oliveira 28 August 2013 (has links)
Neste projeto apresentamos algumas direções de pesquisa desenvolvidas no estudo da geometria/topologia da singularidade, no ambiente real e complexo, para funções e aplicações polinomiais. Para isso, utilizaremos as ferramentas da teoria de estratificação, técnicas de decomposição Open book, condições de regularidade no sentido Malgrange, t-regularidade, \'rho\'E-regularidade e trivialidade topológica no infinito / On this project we present some research lines developed in the study of the geometry/ topology of singularity, on the real and complex settings, for functions and polynomial mappings. For this, we use tools from stratification theory, techniques of Open Book decomposition, Malgrange regularity condition, t-regularity condition, \'rho\'E-regularity and topological triviality at infinity
233

Existência e simetrias para uma equação elíptica não-linear com potencial monopolar e anisotrópico

Amorim, Charles Braga 27 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This master thesis is concerned to nonlinear elliptic problem with mono-polar anisotropic potential u + u|u|p−1 + v (x)u + f(x) = 0 in Rn u(x) - 0, as |x| - 00 provided n > 3 and p > n n−2 . These results, between others things, deals with sub-critical, critical and super-critical nonlinearity. We obtain well-posedness of solutions, regularity in c2(Rn), symmetries and asymptotic behavior of solutions in singular spaces Hk. We employ Banach fixed technique and a theorem of regularity elliptic to get those results, this technique does not need of the Hardy type inequalities and variational methods. / Nesta dissertação estudamos o problema elíptico u + u|u|p−1 + v (x)u + f(x) = 0 em Rn u(x) - 0, quando |x| - 00 sujeito a restrições n > 3 e p > n n−2 , cobrindo os casos sub-críticos, críticos e super-críticos. Obtemos boa-colocação de soluções, regularidade, simetrias de soluções e comportamento assintótico em espaços singulares Hk. Empregamos um argumento de ponto fixo em Hk e Ek ao invés de usar desigualdades do tipo Hardy e métodos variacionais.
234

Newton's method for solving strongly regular generalized equation / Método de Newton para resolver equações generalizadas fortemente regulares

Silva, Gilson do Nascimento 13 March 2017 (has links)
Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-03-22T20:23:25Z No. of bitstreams: 2 Tese - Gilson do Nascimento Silva - 2017.pdf: 2015008 bytes, checksum: e0148664ca46221978f71731aeabfa36 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-03-23T11:30:21Z (GMT) No. of bitstreams: 2 Tese - Gilson do Nascimento Silva - 2017.pdf: 2015008 bytes, checksum: e0148664ca46221978f71731aeabfa36 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-23T11:30:21Z (GMT). No. of bitstreams: 2 Tese - Gilson do Nascimento Silva - 2017.pdf: 2015008 bytes, checksum: e0148664ca46221978f71731aeabfa36 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-03-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / We consider Newton’s method for solving a generalized equation of the form f(x) + F(x) 3 0, where f : Ω → Y is continuously differentiable, X and Y are Banach spaces, Ω ⊆ X is open and F : X ⇒ Y has nonempty closed graph. Assuming strong regularity of the equation and that the starting point satisfies Kantorovich’s conditions, we show that the method is quadratically convergent to a solution, which is unique in a suitable neighborhood of the starting point. In addition, a local convergence analysis of this method is presented. Moreover, using convex optimization techniques introduced by S. M. Robinson (Numer. Math., Vol. 19, 1972, pp. 341-347), we prove a robust convergence theorem for inexact Newton’s method for solving nonlinear inclusion problems in Banach space, i.e., when F(x) = −C and C is a closed convex set. Our analysis, which is based on Kantorovich’s majorant technique, enables us to obtain convergence results under Lipschitz, Smale’s and Nesterov-Nemirovskii’s self-concordant conditions. / N´os consideraremos o m´etodo de Newton para resolver uma equa¸c˜ao generalizada da forma f(x) + F(x) 3 0, onde f : Ω → Y ´e continuamente diferenci´avel, X e Y s˜ao espa¸cos de Banach, Ω ⊆ X ´e aberto e F : X ⇒ Y tem gr´afico fechado n˜ao-vazio. Supondo regularidade forte da equa¸c˜ao e que o ponto inicial satisfaz as hip´oteses de Kantorovich, mostraremos que o m´etodo ´e quadraticamente convergente para uma solu¸c˜ao, a qual ´e ´unica em uma vizinhan¸ca do ponto inicial. Uma an´alise de convergˆencia local deste m´etodo tamb´em ´e apresentada. Al´em disso, usando t´ecnicas de otimiza¸c˜ao convexa introduzida por S. M. Robinson (Numer. Math., Vol. 19, 1972, pp. 341-347), provaremos um robusto teorema de convergˆencia para o m´etodo de Newton inexato para resolver problemas de inclus˜ao n˜ao–linear em espa¸cos de Banach, i.e., quando F(x) = −C e C ´e um conjunto convexo fechado. Nossa an´alise, a qual ´e baseada na t´ecnica majorante de Kantorovich, nos permite obter resultados de convergˆencia sob as condi¸c˜oes Lipschitz, Smale e Nesterov-Nemirovskii auto-concordante.
235

Regularity at infinity and global fibrations of real algebraic maps / Regularidade no infinito e fibrações globais de aplicações algébricas reais

Luis Renato Gonçalves Dias 28 February 2013 (has links)
Let f : \'K POT. \' be a \'C POT. 2\' semi-algebraic mapping for K = R and a polynomial mapping for K = C. It is well-known that f is a locally trivial topological fibration over the complement of the bifurcation set B(f), also called atypical set. In this work, we consider the notion of t-regularity and \'ho E\'-regularity to study the bifurcation set of semi-algebraic mappings f : \'R POT. n\' \'ARROW\' \'R POT. p\' and polynomial mappings f : \'C POT. n\' \'ARROW\' \'C POT. p\'. We show that t-regularity is equivalent to regularity conditions at infinity which have been used by Rabier (1997), Gaffney (1999), Kurdyka, Orro and Simon (2000) and Jelonek (2003) in order to control the asymptotic behaviour of mappings. In addition, we prove that t-regularity implies \'ho E\'-regularity. The \'ho E\'-regularity enables one to define the set of asymptotic non \'ho E\'-regular values S(f) \'This contained\' \' K POT. p\', and the set \'A IND. \'ho E\'\' := f(Singf) U S(f). For \'C POT. 2\' semi-algebraic mappings f : \'R POT. n\' ARROW \' \'R POT. p\' and polynomial mappings f : \'C POT. n\' \'ARROW\' \'C POT. p\', based on a partial Thom stratification at infinity, we rove that S(f) and \'A IND. ho E\' are closed real semi-algebraic sets of dimension at most p - 1 (real dimension at most 2p - 2, for f : \'C POT. n\' \'ARROW\' \'C POT. p\'). Moreover, based on a new fibration theorem at infinity, i.e. holding in the complement of a sufficiently large ball, we obtain B(f) \'this contained\' \'A IND. ho E\'. We study two special classes of polynomial mappings f : \'R POT. n\' \"ARROW\' \'R POT. p\', the class of fair polynomial mappings and the class of Newton non-degenerate polynomial mappings. For fair polynomial mappings, we give an interpretation of t-regularity in terms of integral closure of modules, which is a real counterpart of Gaffney\'s result (1999). For non-degenerate polynomial mappings, we obtain an approximation for B(f) through a set which depends on the Newton polyhedron of f (results like this have been obtained by Némethi and Zaharia (1990) for polynomial functions f : \'C POT. n\' \'ARROW\' C and recently for mixed polynomial functions by Chen and Tibar (2012)). To finish, we discuss some simple consequences of our work: the equivalence t regularity Rabier (equivalently Gaffney, Kuo-KOS, Jelonek) condition for mappings f : X \'ARROW\' \'K POT. p\', where X \'this contained\' \'K POT. n\' is a smooth ane variety; the problem of bijectivity of semi-algebraic mappings; and a formula to compute the Euler characteristic of regular fibres of polynomial mappings f : \'R POT. n\' \'AROOW\' \'R POT. n-1\'. The above results are also extensions of some results obtained, for polynomial functions f : \'K POT. n\' \'ARROW K, by Némethi and Zaharia (1990), Siersma and Tibar (1995), Paunescu and Zaharia (1997), Parusinski (1995) and Tibar (1998). Title: Regularity at infinity and global fibrations of real algebraic maps / Considere f : \'K POT. n\' \"SETA\' \'K POT. p\' uma aplicação semi-algébrica de classe \'C POT. 2\' para K = R e uma aplicação polinomial para K = C. Por resultados clássicos, sabe-se que f é uma fibração topologicamente trivial sobre o complementar dos valores de bifurcação B(f), também chamado de valores atípicos. Neste trabalho, consideramos a t-regularidade e a \'ho E\'-regularidade no estudo dos valores de bifurcação de aplicações semi-algébricas f : \'R POT. n\' \'SETA\' \'R POT. p\' de classe \'C POT. 2\' e aplicações polinomiais f : \'C POT. n\' \'SETA\' \'C POT. p\'. Mostramos que t-regularidade é equivalente às condições de regularidade no infinito usadas por Rabier (1997), Gaffney (1999), Kurdyka, Orro e Simon (2000) e Jelonek (2003) no controle do comportamento assintótico de aplicações. Também mostramos que t-regularidade implica \'ho E\'-regularidade. Através da \'ho E\'-regularidade, definimos o conjunto dos valores assintóticos não \'ho E\'- regulares S(f) \'K POT. p\', e o conjunto \'A IND. ho E\' : = f(Singf) U S(f). Para aplicações semialgébricas f : \'R POT. n\' \'SETA\' \'R POT. p\' de classe \'C POT. 2\' e aplicações polinomiais f : \'C POT. \' \'SETA\' \'C POT. p\', baseados na existência de uma estraticação parcial de Thom no infinito, provamos que S(f) e \'A IND. ho E\' são conjuntos semi-algébricos reais de dimensão no máximo p - 1 (dimensão real no máximo 2p 2, para f : \'C POT. \' \'SETA\' \' C POT. p\'). Além disso, baseados em um novo teorema de fibração no infinito, ou seja na existência de fibração no complementar de uma bola de raio suficientemente grande, obtemos que o conjunto de bifurcação B(f) está contido no conjunto \'A IND. ho E\'. Estudamos também duas classes de aplicações polinomiais f : \'R POT. n\' \'SETA\' \'R POT. p\', a classe de aplicações polinomiais fair e a classe de aplicações Newton não degeneradas. Para aplicações polinomiais fair, obtemos uma interpretação da t-regularidade em termos da teoria de fecho integral de módulos, estendendo para o caso real os resultados de Gaffney (1999). Para aplicações não degeneradas, obtemos uma aproximação de B(f) através de um conjunto que depende do poliedro de Newton de f (resultados deste tipo foram obtidos por Némethi e Zaharia (1990) para funções polinomiais f : \'C POT. \' \'SETA\' C e recentemente para funções polinomiais mistas por Chen e Tibar (2012)). No final, discutimos algumas consequências simples do nosso trabalho: a equivalência t-regularidade condição de Rabier (equivalentemente Gaffney, Kuo-KOS, Jelonek) para aplicações f : X \'SETA\' \'K POT. p\', onde X \'está contido\' \'K POT. n\' é uma variedade suave afim; o problema de bijetividade de aplicações semi-algébricas; e uma fórmula para o cálculo da característica de Euler de fibras regulares de aplicações polinomiais f : \'R POT. n\' \'SETA\' \'R POT. n-1\'. Os resultados acima também são extensões de alguns resultados obtidos para funções polinomiais f : \'K POT. n\' \'SETA\' K, por Némethi e Zaharia (1990), Siersma e Tibar (1995), Paunescu e Zaharia (1997), Parusinski (1995) e Tibar (1998). Título: Regularidade no infinito e fibrações globais de aplicações algébricas reais
236

Etude de la bornitude des transformées de Riesz sur Lp via le Laplacien de Hodge-de Rham / Boundedness of the Riesz transforms on Lp via the Hodge-de Rham Laplacian

Magniez, Jocelyn 06 November 2015 (has links)
Cette thèse comporte deux sujets d’étude mêlés. Le premier concerne l’étude de la bornitude sur Lp de la transformée de Riesz d∆-½ , où ∆ désigne l’opérateur de Laplace-Beltrami (positif). Le second traite de la régularité de Sobolev W1,p de la solution de l’équation de la chaleur non perturbée. Nous établissons également quelques résultats concernant les transformées de Riesz d’opérateurs de Schrödinger avec un potentiel comportant éventuellement une partie négative.Dans le cadre de ces travaux, nous nous plaçons sur une variété riemanienne (M, g) complète et non compacte. Nous supposons que M satisfait la propriété de doublement de volume (de constante de doublement égale à D) ainsi qu’une estimation gaussienne supérieure pour son noyau de la chaleur (celui associé à l’opérateur ∆). Nous travaillons avec le laplacien de Hodge-de Rham, noté ∆, agissant sur les 1-formes différentielles de M. En s’appuyant sur la formule de Bochner, liant ∆ à la courbure de Ricci de M, nous assimilons ∆ à un opérateur de Schrödinger à valeurs vectorielles. C’est un argument de dualité, basé sur une formule de commutation algébrique, qui lie l’étude de ∆ à celle de ∆. [...] / This thesis has two main parts. The first one deals with the study of the boundedness on Lp of the Riesz transform d∆-½ , where ∆ denotes the nonnegative Laplace-Beltrami operator. The second one deals with the Sobolev regularity W1,p of the solution of the heat equation. We also establish some results on the Riesz transforms of Schrödinger operators with a potential possibly having a negative part. In this work, we consider a complete non-compact Riemannian manifold (M, g). We assume that M satisfies the volume doubling property (with doubling constant equal to D) as well as a Gaussian upper estimate for its heat kernel associated to the operator ∆. We work with the Hodge-de Rham Laplacian ∆, acting on 1-differential forms of M. With the Bochner formula, linking ∆to the Ricci curvature of M, we see ∆ has a vector-valued Schrödinger operator. It is a duality argument, based on a commutation formula, which links the study of ∆to the one of ∆. [...]
237

Comportement en temps long des solutions de quelques équations de Hamilton-Jacobi du premier et second ordre, locales et non-locales, dans des cas non-périodiques / Long time behavior of solutions of some first and second order, local and nonlocal Hamilton-Jacobi equations in non-periodic settings

Nguyen, Thi Tuyen 01 December 2016 (has links)
La motivation principale de cette thèse est l'étude du comportement en temps grand des solutions non-bornées d'équations de Hamilton-Jacobi visqueuses dans RN en présence d'un terme d'Ornstein-Uhlenbeck. Nous considérons la même question dans le cas d'une équation de Hamilton-Jacobi du premier ordre. Dans le premier cas, qui constitue le cœur de la thèse, nous généralisons les résultats de Fujita, Ishii et Loreti (2006) dans plusieurs directions. La première est de considérer des opérateurs de diffusion plus généraux en remplaçant le Laplacien par une matrice de diffusion quelconque. Nous considérons ensuite des opérateurs non-locaux intégro-différentiels de type Laplacien fractionnaire. Le second type d'extension concerne le Hamiltonien qui peut dépendre de x et est seulement supposé sous-linéaire par rapport au gradient. / The main aim of this thesis is to study large time behavior of unbounded solutions of viscous Hamilton-Jacobi equations in RN in presence of an Ornstein-Uhlenbeck drift. We also consider the same issue for a first order Hamilton-Jacobi equation. In the first case, which is the core of the thesis, we generalize the results obtained by Fujita, Ishii and Loreti (2006) in several directions. The first one is to consider more general operators. We first replace the Laplacian by a general diffusion matrix and then consider a non-local integro-differential operator of fractional Laplacian type. The second kind of extension is to deal with more general Hamiltonians which are merely sublinear.
238

Les noms verbaux dans le parler berbère de ksar Tit n'Ali : étude morphophonologique / The names in the records speak Berber Ksar Tit n'Ali : morphophonological study

Krim, Abdelaaziz 19 May 2016 (has links)
La formation des noms qui dèrivent d'un verbe n'est pas une chose simple. Ce qui rend la complexité de ce type de dérivation apparente, la mise en œuvre de plusieurs stratégies morphologiques. Notre travail sera consacré à l'étude de la structure des noms verbaux du berbère de ksar Tit n'Ali au sein du cadre théorique de la phonologie autosegmentale, et plus particulièrement du modèle CVCV (Lowenstam 1996). / This thesis contributes to the study about nouns related to verbs of the berber language spoken in Ksar Tit n’Ali (a region located on the Valley of High Guir in southern Morocco). This work aims to show, firstly, the nouns derived from verbs considered “common”or “normal” which refer to an action, in this case: action nouns, agent nouns and instrument nouns. Secondly, the verbs derived from stative verbs, especially: quality nouns and nouns we called unofficially stative nouns. As we analysed the collected informations, we found out that the existence of plenty of verbal roots and the implementation of several strategies makes this derivational operation very far from being clear. Our goal is to demonstrate the various mechanisms operated to reconcile between a - concatenative- external morphology and internal morphology -non concatenative- in order to achieve a pattern. We aim to clear the final templatic scheme that is subject to major constraints on the lexicon or the result of a morphological process. In addition, given the importance of the left site in the derivation of nominal units, we devoted a chapter to the question of the initial vowel equipment and its relationship with the passage from free status of an item to its status of annexation. Starting from the findings of predecessors and analyzing the elements of the spoken language, which is the object of our research, we realize fertility of linguistic literature in this case has not resolved our problematic completely.
239

Factors influencing the choice to shop online : a psychological study in a South African context

De Swardt, Maray Annelise 25 November 2008 (has links)
As the Internet and online shopping is growing at a very fast pace worldwide, investigating this phenomenon within a South African context is crucial considering that it is a relatively new trend in this country. Typical of new trends and phenomena is the absence of research already conducted, resulting in a lack of existing literature. Very few studies have examined the factors and reasons that entice South Africans to utilise this modern shopping channel, and even less have used an in-depth, qualitative approach. To assist in filling this void, this research study examines people’s reasons for taking up or not taking up online shopping, from a South African perspective. A snowball sampling method was used to identify participants fitting the predetermined sample criteria and in-depth qualitative interviews were conducted with all participants. The theoretical approach used in the analysis was social constructionism. Findings are presented by means of constructions identified during the data analysis, and these indicated that saving time, the convenience of products being increasingly available and accessible and being able to make price comparisons easily are the main advantages of online shopping. Main disadvantages were not being able to touch and feel products, and the absence of a salesperson. Limitations of the research are discussed, along with recommendations for online retailers and future research. / Dissertation (MA)--University of Pretoria, 2008. / Psychology / unrestricted
240

Regularity And Propagation Phenomena In Some Linear And Non-Linear Partial Differential Equations With Particular Reference To Microlocal Analysis

Jain, Rahul 03 1900 (has links) (PDF)
No description available.

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