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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.
41

Inference for Bivariate Conway-Maxwell-Poisson Distribution and Its Application in Modeling Bivariate Count Data

Wang, Xinyi January 2019 (has links)
In recent actuarial literature, the bivariate Poisson regression model has been found to be useful for modeling paired count data. However, the basic assumption of marginal equi-dispersion may be quite restrictive in practice. To overcome this limitation, we consider here the recently developed bivariate Conway–Maxwell–Poisson (CMP) distribution. As a distribution that allows data dispersion, the bivariate CMP distribution is a flexible distribution which includes the bivariate Poisson, bivariate Bernoulli and bivariate Geometric distributions all as special cases. We discuss inferential methods for this CMP distribution. An application to automobile insurance data demonstrates its usefulness as an alternative framework to the commonly used bivariate Poisson model. / Thesis / Master of Science (MSc)
42

The Impact Dynamics of Weakly Charged Droplets

Gao, Fan 07 August 2019 (has links)
Electric charges are often found in naturally or artificially formed droplets, such as raindrops and those generated by Kelvin's water dropper. In contrast to the impact of neutral droplets on a flat solid surface upon which a thin convex lens shape layer of the gas film is typically formed, I show that the delicate gas thin film can be fundamentally altered for even weakly charged droplets both experimentally and numerically. As the charge level is raised above a critical level of about 1% of the Rayleigh limit for representative impact conditions, the Maxwell stress overcomes the gas pressure buildup to deform the droplet bottom surface. A conical liquid tip forms and pierces Through the gas film, leading to a circular contact line moving outwards that does not trap any gas. The critical charge level only depends on the capillary number based on the gas viscosity. The deformation applies to common liquids and molten alloy droplets. Even dielectric surfaces can also induce conical deformation. The charged droplets can also deform upon hydrophobic surfaces, and increase the contact time on hydrophobic surfaces or even avoid bouncing. / Doctor of Philosophy / Electric charges are often found in naturally or artificially formed droplets, such as raindrops, waterfall, and inkjet printer. Neutral droplets impact on flat surfaces will usually trap a bubble inside because of the viscosity of air. The air bubble entrapped can be ignored if the droplet is water because the air bubble will eventually pinch-off. However, if the droplet is metal or some other viscous liquid, the air bubble will stay inside the liquid. This entrapped air bubble is undesired under some circumstances. For example, the existence of air bubble during metal 3D printing can influence the physical property. I show that the delicate gas thin film can be fundamentally altered for even weakly charged droplets both experimentally and numerically. As the charge level is raised above a critical level of about 1% of the maximum charges a droplet can carry for representative impact conditions, the electric stress will dominate the deformation of droplet. A conical liquid tip forms at the droplet bottom, avoiding the entrapment of air bubble. The critical charge level is experimentally proved to be only dependent on the gas viscosity and impact velocity. The deformation applies to common liquids and molten alloy droplets. Even dielectric surfaces can also induce conical deformation. The charged droplets can also deform upon hydrophobic surfaces, and increase the contact time on hydrophobic surfaces or even avoid bouncing.
43

The use of parody in Peter Maxwell Davies' Taverner and related works.

Pilkington, Shirley Anne. January 1990 (has links)
Parody is a concept central to much of the work of Peter Maxwell Davies. In this study the First Fantasia on an In Nomine by John Taverner, the Seven In Nomine, the Second Fantasia on an In Nomine by John Taverner and the opera Taverner are used as case studies of Davies' use of parody. Three categories of parody are discerned: parody in its pre-Baroque sense which entails the use of musical material from pre-existing compositions; parody in its modern sense whereby a particular work or style is imitated in such a manner that the source is ridiculed or satirized; and the non-satirical parody of compositional devices, forms or other features characteristic of a particular musical period. All four works examined in this study use the 'In nomine' by the sixteenth-century composer John Taverner as a source of pre-compositional musical material. Each of Davies' In Nomine works is examined in detail and the composer's use of the device and its function in each instance is discussed. The chronological consideration of the In Nomine compositions, and of Taverner in particular, reveals a gradual change in the manner in which Davies employed parody in his compositions. Attention is thus given to the transition from the emphasis on parody in the Renaissance sense to the emphasis on parody in its modern sense and it is shown. that this transition clearly parallels the change that was taking place within Davies' general compositional style during the sixties. In conclusion, some reasons for the predominant role played by parody in Davies' output and the preoccupation with musical materials derived from the pre-Baroque are suggested, in order to show the relevance of Davies' use of parody within a twentieth-century context. / Thesis (M.Mus.)-University of Natal, Durban, 1990.
44

Efeitos da geometria e da composição no espectro de cristais fotônicos 2D /

Sereguetti, Janaine Maria. January 2012 (has links)
Orientador: Alexys Bruno Alfonso / Banca: Lucila Helena Deliesposte Cesgato / Banca: Clarissa de Almeida Olivati / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem carater institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: Os cristais fotônicos têm recebido grande atenção da comunidade científica nos últimos anos. As suas aplicações incluem a construção de guias de onda, chips ópticos e células solares, o controle de emissão de radiação e o gerenciamento de informações. Neste trabalho são calculados os modos de propagação de ondas eletromagnéticas em cristais fotônicos bidimensionais. Os cristais estudados são arranjos de fios circulares infinitos de um tipo de meio óptico, imersos numa matriz de outro meio óptico. As estruturas cristalinas consideradas são a quadrada simples, hexagonal simples e honeycomb. É analisada a propagação perpendicular aos fios e, portanto, são consideradas duas polarizações: a transversão elétricas e a transversal magnética. Os cálculos numéricos são realizados para diferentes combinações dos materiais que compõem o cristal fotônico. Isto permite investigar como o espectro fotônico depende da geometria do cristal e do contraste entre os meios ópticos que o compõem. Para resolver a equação de ondas, o campo eletromagnético é expresso como combinação linear de um conjunto de ondas harmônicas planas. Foi encontrado bom acordo entre as frequencia calculadas e resultados disponíveis na literatura do tema, corroborando a existência de gaps fotônicos parciais nas estrutuaras simples e gaps fotônicos completos na estrutura honeycomb. Além disso, verificou-se que o surgimento de gaps requer menor constrate de índice de refração no caso hexagonal, quando comparado com o quadrado / Abstract: Photoic crystals have received some attention from the scientific community in the las years. Their applications include the fabrication of waveguides, optical chips and solar cells, control of radiation emission and information management. In this work, the propagation of electromagnetic waves in two-dimensional photonic crystals is theoretically investigated. The structures under study are periodic arrangements of infinite circular wires of a given optical medium, immersed in a matrix of another optical medium. The considered cyrstalline structures are the simple square, the simple hexagonal and the honeycomb lattices. Only the propagation perpendicular to the wires is analyzed. Hence, we consider two polarizations: transverse electrical and transverse magnetic. The calculations are performed for different combinations of the materials composing the crystal. This allows the investigation of how the photonic spectrum depends on both the crystal geometry and the contrast between the refractuve index of the composing materials. The wave equation is solved by expressing the solution as a linear combination of a set of harmonic plane waves. Good agreement between the calculated frequencies and the results available in the literature is found, thus confirming the existence of partial photonic gaps in the simple lattices and complete photonic gaps in the honeycomb lattice. Moreover, it was verified that occurrence of gaps in the hexagonal case requires less refractive-index contrast, when compared with the square one / Mestre
45

Efeitos da geometria e da composição no espectro de cristais fotônicos 2D

Sereguetti, Janaine Maria [UNESP] 29 June 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:30:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-29Bitstream added on 2014-06-13T20:40:14Z : No. of bitstreams: 1 sereguetti_jm_me_bauru.pdf: 655401 bytes, checksum: f8b80337046a58d12f1aed1d4dc5a28c (MD5) / Os cristais fotônicos têm recebido grande atenção da comunidade científica nos últimos anos. As suas aplicações incluem a construção de guias de onda, chips ópticos e células solares, o controle de emissão de radiação e o gerenciamento de informações. Neste trabalho são calculados os modos de propagação de ondas eletromagnéticas em cristais fotônicos bidimensionais. Os cristais estudados são arranjos de fios circulares infinitos de um tipo de meio óptico, imersos numa matriz de outro meio óptico. As estruturas cristalinas consideradas são a quadrada simples, hexagonal simples e honeycomb. É analisada a propagação perpendicular aos fios e, portanto, são consideradas duas polarizações: a transversão elétricas e a transversal magnética. Os cálculos numéricos são realizados para diferentes combinações dos materiais que compõem o cristal fotônico. Isto permite investigar como o espectro fotônico depende da geometria do cristal e do contraste entre os meios ópticos que o compõem. Para resolver a equação de ondas, o campo eletromagnético é expresso como combinação linear de um conjunto de ondas harmônicas planas. Foi encontrado bom acordo entre as frequencia calculadas e resultados disponíveis na literatura do tema, corroborando a existência de gaps fotônicos parciais nas estrutuaras simples e gaps fotônicos completos na estrutura honeycomb. Além disso, verificou-se que o surgimento de gaps requer menor constrate de índice de refração no caso hexagonal, quando comparado com o quadrado / Photoic crystals have received some attention from the scientific community in the las years. Their applications include the fabrication of waveguides, optical chips and solar cells, control of radiation emission and information management. In this work, the propagation of electromagnetic waves in two-dimensional photonic crystals is theoretically investigated. The structures under study are periodic arrangements of infinite circular wires of a given optical medium, immersed in a matrix of another optical medium. The considered cyrstalline structures are the simple square, the simple hexagonal and the honeycomb lattices. Only the propagation perpendicular to the wires is analyzed. Hence, we consider two polarizations: transverse electrical and transverse magnetic. The calculations are performed for different combinations of the materials composing the crystal. This allows the investigation of how the photonic spectrum depends on both the crystal geometry and the contrast between the refractuve index of the composing materials. The wave equation is solved by expressing the solution as a linear combination of a set of harmonic plane waves. Good agreement between the calculated frequencies and the results available in the literature is found, thus confirming the existence of partial photonic gaps in the simple lattices and complete photonic gaps in the honeycomb lattice. Moreover, it was verified that occurrence of gaps in the hexagonal case requires less refractive-index contrast, when compared with the square one
46

Formulações equivalentes da lei de Faraday / Equivalent formulations of Faraday's law

Rodrigues, Fabio Grangeiro, 1980- 15 August 2018 (has links)
Orientador: Edmundo Capelas de Oliveira / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-15T07:12:57Z (GMT). No. of bitstreams: 1 Rodrigues_FabioGrangeiro_M.pdf: 2473878 bytes, checksum: edf9dfdf8d0b07b971df24b68798f67f (MD5) Previous issue date: 2010 / Resumo: Neste trabalho é dada uma prova de equivalência entre diferentes formas de se escrever a lei de Faraday. a forma integral e a diferencial. Nosso objetivo é esclarecer alguns pontos relevantes da prova dessas equivalências que são normalmente apresentadas nos livros textos de Física apenas para casos muito particulares. Aqui apresentamos a derivação das ditas equivalências para uma situação geral. Incluímos também as ferramentas matemáticas necessárias para o tratamento rigoroso do nosso problema / Abstract: In this work we give a rigorous proof of the equivalence of some different forms of Faraday's law of induction clarifying some misconceptions on the subject and emphasizing that many derivations of this law appearing in textbooks and papers are only valid under very special circunstances and not satisfactory under a mathematical point of view. We include also the mathematical apparatus necessary for a rigorous presentation of our subject / Mestrado / Fisica-Matematica / Mestre em Matemática Universitária
47

Résolution des équations de Maxwell tridimensionnelles instationnaires sur architecture massivement multicoeur / Resolution of tridimensional instationary Maxwell's equations on massively multicore architecture

Strub, Thomas 13 March 2015 (has links)
Cette thèse s'inscrit dans un projet d'innovation duale RAPID financé par DGA/DS/MRIS et appelé GREAT faisant intervenir la société Axessim, l'ONERA, INRIA, l'IRMA et le CEA. Ce projet a pour but la mise en place d'une solution industrielle de simulation électromagnétique basée sur une méthode Galerkin Discontinue (GD) parallèle sur maillage hexaédrique. Dans un premier temps, nous établissons un schéma numérique adapté à un système de loi de conservation. Nous pouvons ainsi appliquer cette approche aux équations de Maxwell, mais également à tout système hyperbolique. Dans un second temps, nous mettons en place une parallélisation à deux niveaux de ce schéma. D'une part, les calculs sont parallélisés sur carte graphique au moyen de la bibliothèque OpenCL. D'autre part, plusieurs cartes graphiques peuvent être utilisées, chacune étant pilotée par un processus MPI. De plus, les communications MPI et les calculs OpenCL sont asynchronisés permettant d'obtenir une forte accélération. / This thesis is part of a dual innovation project funded by RAPID DGA/DS/MRIS and called GREAT involving Axessim company, ONERA, INRIA, IRMA and the CEA. This project aims at the establishment of an industrial solution of electromagnetic simulation based on a method Discontinuous Galerkin (DG) on parallel hexahedral mesh. First, we establish a numerical scheme adapted to a conservation law system. We can apply this approach to the Maxwell equations but also to any hyperbolic system. In a second step, we set up a two-level parallelization of this scheme. On the one hand, the calculations are parallelized on graphics card using the OpenCL library. On the other hand, multiple graphics cards can be used, each driven by a MPI process. In addition, MPI communications and OpenCL computations are launched asynchronously in order to obtain a strong acceleration.
48

Mathematical modelling for hybrid and nanoparticle imaging / Modélisation mathémathique pour l'imagerie hybride et des nano-particules

Millien, Pierre 05 June 2015 (has links)
Cette thèse a pour sujet la modélisation mathématique de nouvelles méthodes expérimentales d'imagerie. Elle est divisée en deux parties. La première porte sur l'étude de techniques dites hybrides basées sur des interactions entre différents types d'ondes. La deuxième parte est consacrée à l'étude du comportement des nano-particules métalliques soumises à des champs électro-magnétiques. La première partie contient trois chapitres dans lesquels sont étudiés trois techniques d'imagerie différentes : - la tomographie magnéto-acoustique par force de Lorentz ; - la tomographie magnéto-acoustique par induction magnétique ; - l'élastographie par tomographie cohérente optique. Dans les deux premiers chapitres nous donnons un modèle mathématique explicite pour les expériences étudiées, ainsi que des formules explicites pour résoudre les problèmes inverses associés. Nous introduisons une méthode de reconstruction directe dite de « viscosité » permettant de reconstruire la conductivité électrique du milieu étudié. Dans le troisième chapitre nous proposons une méthode d'optimisation pour récupérer le module de cisaillement du milieu à partir de mesures d'un champs de déplacement. La deuxième partie contient deux chapitres dans lesquels sont étudiés la diffraction par de petites particules. Les phénomènes suivant sont abordés : - les résonances plasmoniques ; - la génération de seconde harmonique. Nous étudions les résonances plasmoniques dans le cadre d'une approximation petit volume. / In this thesis we study the mathematical modelling of new experimental imaging techniques. It is divided in two parts. The first one contains work on hybrid imaging techniques based on the interactions betwenn different types of waves. The second part is devoted to the study of the behavior of metallic nanoparticles embedded in electromagnetic fields. The first part contains three chapters in which three different imaging techniques are studied : - magneto-acoustic tomography by Lorentz force, - magneto-acoustic tomography with magnetic induction, - optical coherence tomography based elastography. In the first two chapters we give a mathematical model for the experiments studied as well as explicit reconstruction formulas for the associated inverse problems. We introduce a new direct reconstruction method ("viscosity method") allowing the recovery of the electrical conductivity of the medium. In the third chapter we give an optimisation method to reconstruct the shear modulus of the medium from a displacement field. The second part contains two chapters in which are studied the diffraction of light by small metallic nanoparticles. We study: - plasmonic resonances, - second harmonic generation. The plasmonic resonances are studied within the Maxwell frame. We give an asymptotic formula for the electromagnetic fields within a small volume approximation.
49

Simulace provozních stavů synchronního generátoru v ostrovním provozu / Simulation of synchronous generator at insular operation

Kořistka, Petr January 2012 (has links)
This work deals with a creation of model of synchronous generator in programmes such as Simplorer and Maxwell, and also its operation in an insular operation. In the paper are described Maxwells equations for solving electromagnetic field, theory of synchronous machine, further are briefly described a simulation programmes which were used. In the next part of work is described production of geometric model of generator and its later electromagnetic analysis in the Maxwell programmes environment. For a simulation of generators operation in insular operation were chosen 2 cases. The first case simulates an operation of generator at the step change of residence of R-L load, the second simulation an automatic regulation of voltage at the step change of residence of R-L load. The simulations were running in the Simplorer programme and at link simulation Maxwell Simplorer programmes.
50

[pt] ASPECTOS GEOMÉTRICOS DE POLIGONAIS GENÉRICAS: CURVATURA TOTAL E CONVEXIDADE / [en] GEOMETRICAL ASPECTS OF GENERIC POLYGONAL LINES: TOTAL CURVATURE AND CONVEXITY

SAMUEL PACITTI GENTIL 24 September 2020 (has links)
[pt] O objetivo deste trabalho é o de estudar propriedades geométricas de curvas poligonais genéricas. Inicialmente abordamos resultados clássicos para curvas quanto à sua curvatura total no caso discreto e discutimos aqueles pertinentes a nós poligonais. Também é feito o estudo do Grafo de Maxwel para poligonais. No caso, temos uma interessante relação entre a natureza do grafo quanto ao seu número de componentes e à condição de a poligonal ser ou não convexa. / [en] The aim of this work is to study geometrical properties of generic polygonal lines. We begin with some classical results for curves with respect to total curvature, in the discrete case, and discuss results related to polygonal knots. Maxwell graphs are also considered for polygonal lines: We study the relation between the number of components of the graph and the convexity of the polygonal line.

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