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This paper presents the results of the estimations made in the process arising from the solution of classical Langevin equation with Brownian motion noise, and generalized, with α-stable noise. We perform the estimation of the parameter λ related to the memory function of such processes and the parameter α when the noise is a process with α-stable distribution. The estimation of λ is obtained from the maximum likelihood method, the ordinary least squares method and from the sample autocovariance function of the process. We discuss the types of noise that may be associated to the Langevin equation and present the Existence and Uniqueness theorem of Kannan and Kannan representation formula, which prove the existence and uniqueness of the solution for the generalized Langevin equation and presents criteria for the form of such solution.

Thesis (M.Sc.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2009/06/29). Includes bibliographical references.

This paper presents the results of the estimations made in the process arising from the solution of classical Langevin equation with Brownian motion noise, and generalized, with α-stable noise. We perform the estimation of the parameter λ related to the memory function of such processes and the parameter α when the noise is a process with α-stable distribution. The estimation of λ is obtained from the maximum likelihood method, the ordinary least squares method and from the sample autocovariance function of the process. We discuss the types of noise that may be associated to the Langevin equation and present the Existence and Uniqueness theorem of Kannan and Kannan representation formula, which prove the existence and uniqueness of the solution for the generalized Langevin equation and presents criteria for the form of such solution.

This paper presents the results of the estimations made in the process arising from the solution of classical Langevin equation with Brownian motion noise, and generalized, with α-stable noise. We perform the estimation of the parameter λ related to the memory function of such processes and the parameter α when the noise is a process with α-stable distribution. The estimation of λ is obtained from the maximum likelihood method, the ordinary least squares method and from the sample autocovariance function of the process. We discuss the types of noise that may be associated to the Langevin equation and present the Existence and Uniqueness theorem of Kannan and Kannan representation formula, which prove the existence and uniqueness of the solution for the generalized Langevin equation and presents criteria for the form of such solution.

Made available in DSpace on 2014-06-12T18:07:23Z (GMT). No. of bitstreams: 2 arquivo7880_1.pdf: 2203811 bytes, checksum: a135545fec850459bf67bc6250f2951c (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2005 / Universidade Federal do Piauí / Fluidos magnéticos vem se constituindo um tópico de grande destaque em termos de pesquisa teórica e experimental. Esses sistemas, compostos de nanopartículas mon¬odomínios dispersas em líquido carreador, apresentam propriedades magnéticas e líquidas que os tornam bastante versáteis, possibilitando o desenvolvimento de inúmeras aplicações. O conhecimento detalhado dessas propriedades é importante no desenvolvimento de aplicações tecnológicas, que vão desde a fabricação de impressoras que utilizam tintas magnéticas, selos e juntas para alto vácuo, até aplicações biológicas. Nesse sentido, estu¬damos as propriedades magnéticas de amostras de fluidos magnéticos de dupla camada elétrica, composto de nanopartículas de ferrita de cobalto, para diferentes diâmetros médios (4,5nm-ll,6nm). Medidas de difração de raios X foram realizadas para investigar a estrutura cristalina e fornecer o diâmetro médio das partículas que compõem os ferrofluidos. As medidas de magnetização estática foram realizadas através de um Magnetâmetro do tipo Foner. As curvas de magnetização em função do campo magnético, obtidas para as diferentes amostras, apresentaram um comportamento superparamagnético. Também, verificamos que a magnetização de saturação reduz à medida que diâmetro médio é reduzido, eviden¬ciando os efeitos de superfície. Trabalhamos com o modelo Langevin, juntamente com a distribuição log normal, para considerar a polidispersão, sobre as curvas de magnetização. Desta forma foi possível determinar os parâmetros de distribuição de diâmetros (dispersão e diâmetro médio) e momentos. Além disso. verificamos que a relação ele momento médio e diâmetro médio com ferritas ele Manganês e Cobre. Analisamos o comportamento ela magnetização ele saturação elas amostras de ferrofluidos à base ele Cobalto com valores típicos ele amostras à, base de Manganês e Cobre. E por fim verificamos que em nossas amostras apresentam interação dipolar totalmente desprezível a partir da análise de baixos campos

In Andre Langevin's five novels, the theme of isolation keeps on coming back. The characters however try by different means to establish a communication with other people but their attempts almost always fail, due to some sort of fatality. / This thesis sheds light on the different attempts by Langevin's characters to establish a relationship with those who surround them. The corpus is composed of Poussiere sur la ville (1953), Le temps des hommes (1956), L'Elan d'Amerique (1972), the latter belonging to the come back of the novelist after a silence of about twenty years. The dialogues and non verbal communications as they are established among the characters will successively be analyzed. The third novel, L'Elan d'Amerique, brings unique forms of this theme as it introduces a new style of the author, which has been compared to the "nouveau roman's". / From one novel to the other, the topic of incommunicability as developed by Langevin, takes new forms as the novelistic scope expands. But this research reveals that, in these three novels, a failure is always witnessed by the characters who never succeed in establishing satisfactory or lasting relationships with others.

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 90-99). Also available for download via the World Wide Web; free to University of Oregon users.

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