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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.
21

White Dwarfs in the Solar Neighborhood

Subasavage, Jr., John P. 03 August 2007 (has links)
The study of white dwarfs (WDs) provides insight into understanding WD formation rates, evolution, and space density. Individually, nearby WDs are excellent candidates for astrometric planetary searches because the astrometric signature is greater than for an identical, more distant WD system. As a population, a complete volume-limited sample is necessary to provide unbiased statistics; however, their intrinsic faintness has allowed some to escape detection. The aim of this dissertation is to identify nearby WDs, accurately characterize them, and target a subset of potentially interesting WDs for follow-up analyses. The most unambiguous method of identifying new WDs is by their proper motions. After evaluating all previous southern hemisphere proper motion catalogs and selecting viable candidates, we embarked on our own southern hemisphere proper motion survey, the SuperCOSMOS-RECONS (SCR) survey. A number of interesting objects were discovered during the survey, including the 24th nearest star system -- an M dwarf with a brown dwarf companion. After a series of spectroscopic observations, a total of 56 new WD systems was identified (18 from the SCR survey and 38 from other proper motion surveys). CCD photometry was obtained for most of the 56 new systems in an effort to model the physical parameters and obtain distance estimates via spectral energy distribution fitting. An independent distance estimate was also obtained by deriving a color-MV relation for several colors based on WDs with known distances. Any object whose distance estimate was within 25 pc was targeted for a trigonometric parallax via our parallax program, CTIOPI. Currently, there are 62 WD systems on CTIOPI. A subset of 53 systems has enough data for at least a preliminary parallax (24 are definitive). Of those 53 systems, nine are previously known WDs within 10 pc that we are monitoring for perturbations from unseen companions, and an additional 29 have distances within 25 pc. Previously, there were 109 known WDs with parallaxes placing them within 25 pc; therefore, our effort has already increased the nearby sample by 27%. In addition, at least two objects show hints of perturbations from unseen companions and need follow-up analyses.
22

Arranjo das fibras gengivais transeptais de ratos Wistar: estudo histomorfométrico e histoquímico

Oliveira, Roberto Sotto-Maior Fortes de 03 February 2010 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-11T12:22:28Z No. of bitstreams: 1 robertosottomaiorfortesdeoliveira.pdf: 16646767 bytes, checksum: fbcd339691975b226d2d9a290fdd5b18 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-11T12:57:06Z (GMT) No. of bitstreams: 1 robertosottomaiorfortesdeoliveira.pdf: 16646767 bytes, checksum: fbcd339691975b226d2d9a290fdd5b18 (MD5) / Made available in DSpace on 2017-08-11T12:57:06Z (GMT). No. of bitstreams: 1 robertosottomaiorfortesdeoliveira.pdf: 16646767 bytes, checksum: fbcd339691975b226d2d9a290fdd5b18 (MD5) Previous issue date: 2010-02-03 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / As fibras transeptais situam-se na lâmina própria da gengiva entre dois dentes adjacentes. São comumente descritas como um grupo de fibras colágenas inseridas no cemento de um dente que seguem diretamente por sobre a crista óssea alveolar inserindo-se em uma região correspondente no cemento do dente adjacente. De maneira distinta, relatou-se na literatura que as fibras transeptais não são contínuas ao longo de toda sua extensão; são originadas dos dentes adjacentes, entrelaçando-se na região central do espaço interproximal. Com o presente estudo, objetivou-se avaliar e quantificar o arranjo das fibras gengivais transeptais empregando-se análise histomorfométrica e histoquímica em cortes histológicos sagitais da região entre primeiro e segundo molares da maxila de 12 ratos Wistar machos. As fibras colágenas foram coradas pelo método de picro-sirius e analisadas por microscopia de luz polarizada linear, processamento e análise digital de imagem baseados em métodos de filtragem e medição por transformada de Fourier. Foram realizadas medidas histomorfométricas de orientação, densidade e dimensão fractal das fibras. O brilho máximo apresentado pelas fibras foi mensurado pelo histograma de intensidade. Os parâmetros quantitativos foram comparados entre três regiões de interesse ao longo da extensão da gengiva interproximal ocupada pelas fibras transeptais utilizando-se análise de variância (ANOVA) seguida de testes post hoc de Bonferroni ou Tamhane T2. Houve um aumento significativo (p < 0,05) nos parâmetros de densidade de ocupação e dimensão fractal das fibras pertencentes à região central quando comparada às regiões próximas aos dentes, sem haver diferença na orientação e na intensidade de brilho das fibras. Os resultados demonstraram quantitativamente um arranjo mais denso de fibras na região central, reforçando o conceito de que as fibras transeptais entrelaçam-se nesta região. / The transeptal fibers are located in the lamina propria of the gingiva between adjacent teeth. They are often described as a group of collagen fibers embedded in the cementum of one tooth that follows a straight path over the alveolar bone crest and embeds itself in the cementum of the adjacent tooth. In a distinct way, it was reported in the literature that the transeptal fibers are not continuous over its full length but originates from the adjacent teeth interlacing in the central area of the interproximal gingiva. The present study aimed to evaluate and quantitate the gingival transseptal fibers arrangement by histomorphometry and histochemistry of sagittally cut tissue sections of the interdental region between first and second maxilar molar teeth of 12 male Wistar rat. The collagen fibers were stained with Picrosirius red staining and assessed with linear polarized light microscopy, digital image processing and analysis based on Fourier transform measurements and filtering techniques. Histomorphometrical parameters like fiber orientation, area fraction and fractal dimension were measured. The maximal brilliance presented by the fibers was evaluated using intensity histogram measurements. These quantitative parameters were compared among three different regions of interest along the length of the interdental gingiva using one-way analysis of variance (ANOVA) and Bonferroni’s or Tamhane’s T2 post hoc tests. There was an increase (p < 0.05) in area fraction and fractal dimension parameters in the central region compared to regions near the teeth, and no difference in the orientation and maximal brilliance of fibers among the tree regions. Our results quantitative demonstrated a denser arrangement of the fibers in the central region reinforcing the model of an interlacement of the transseptal fibers in that region.
23

Di?logos entre saber t?cnico e viv?ncia territorial ? investigando pr?ticas colaborativas para forma??o de comunidades / Dialogues between technical knowledge and territorial experiencing ? analyzing collaborative practices for the construction of communities

Alves, Alexandre Fernandes Alessio 19 February 2018 (has links)
Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2018-05-07T13:25:41Z No. of bitstreams: 1 ALEXANDRE FERNANDES ALESSIO ALVES.pdf: 11849626 bytes, checksum: ed79bafa3e4a5c20c2526652045b6fdc (MD5) / Made available in DSpace on 2018-05-07T13:25:41Z (GMT). No. of bitstreams: 1 ALEXANDRE FERNANDES ALESSIO ALVES.pdf: 11849626 bytes, checksum: ed79bafa3e4a5c20c2526652045b6fdc (MD5) Previous issue date: 2018-02-19 / From the Banco Nacional da Habita??o (National Bank for Housing) in 1960?s to the Minha Casa Minha Vida Program (My House My Life Program), public policy?s strategies for housing development have been designed mainly through what it was referred to as traditional lenses ? aligned with the dominant epistemological paradigm and aimed to the production of housing units, but not to the construction of communities. The study case of Residencial Sirius was found at the intersection between Minha Casa Minha Vida Program and the Estrat?gia para Desenvolvimento Integrado e Sustent?vel de Territ?rios (Integrated and Sustainable Territorial Development Strategy), inaugurated in 2014 for promoting socioterritorial development at preselected residential neighborhoods. Working from a dual role perspective as a technical agent and a researcher, it was possible to practice participant observation at the territory and with local dwellers, approaching Sirius through what it was referred to as dialogical lenses ? based on theories of complex thinking, where subject and object are interdependent and relate in a reciprocal manner. This dialogical approach was characterized by articulating technical knowledge with territorial experiencing, anchored to integrated urban analysis and participant observation. The research expected to stimulate reflections on the role of architects and urbanists in processes for the construction of communities, as well as on the importance of territorial experiencing for architecture and urbanism training programs. Results indicated practical limitations of the Estrat?gia para Desenvolvimento Integrado e Sustent?vel de Territ?rios considering contradictory impacts of Minha Casa Minha Vida Program on priority housing development for low income families. / Estrat?gias da pol?tica p?blica de habita??o foram, do Banco Nacional da Habita??o na d?cada de 1960 ao Programa Minha Casa Minha Vida nos anos 2000, desenhadas predominantemente pelo que se referiu aqui como mirada tradicional ? alinhadas ao paradigma epistemol?gico dominante e orientadas efetivamente para produ??o de unidades habitacionais, mas n?o para forma??o de comunidades. O estudo de caso do Residencial Sirius se encontrou na ?rea de intersec??o do Programa Minha Casa Minha Vida com a Estrat?gia para Desenvolvimento Integrado e Sustent?vel de Territ?rios, lan?ada em 2014 pelo Governo Federal com o objetivo de promover o desenvolvimento socioterritorial em empreendimentos pr?-selecionados. A dupla atua??o do autor como agente t?cnico e pesquisador permitiu exercitar a observa??o participante no territ?rio e com os moradores locais, lan?ando ao objeto de estudo a mirada referida como dial?gica ? vinda pelo paradigma do pensamento complexo, onde sujeito e objeto s?o interlocutores e se relacionam de forma rec?proca. A mirada dial?gica foi caracterizada pela articula??o entre saber t?cnico e viv?ncia territorial, ancorada na an?lise urban?stica integrada e na experi?ncia vivencial. A pesquisa prop?s refletir sobre as contribui??es do arquiteto urbanista em processos colaborativos e participativos para forma??o de comunidades, bem como sobre a import?ncia da experi?ncia vivencial para os programas de forma??o em arquitetura e urbanismo. Os resultados obtidos apontaram limita??es pr?ticas da Estrat?gia para Desenvolvimento Integrado e Sustent?vel de Territ?rios frente a impactos contradit?rios do Programa Minha Casa Minha Vida na promo??o habitacional para a demanda priorit?ria.
24

Controle discreto de fonte modular de corrente aplicada a magnetos de aceleradores de partículas

Oliveira, Fernando Henrique de 23 February 2018 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-05-23T18:23:25Z No. of bitstreams: 1 fernandohenriquedeoliveira.pdf: 7733433 bytes, checksum: ed0bfbea1ebdeec7443503ad20027a67 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-05-24T17:33:19Z (GMT) No. of bitstreams: 1 fernandohenriquedeoliveira.pdf: 7733433 bytes, checksum: ed0bfbea1ebdeec7443503ad20027a67 (MD5) / Made available in DSpace on 2018-05-24T17:33:19Z (GMT). No. of bitstreams: 1 fernandohenriquedeoliveira.pdf: 7733433 bytes, checksum: ed0bfbea1ebdeec7443503ad20027a67 (MD5) Previous issue date: 2018-02-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta dissertação apresenta uma proposta de controle discreto baseado em reali-mentação de estados aplicado à fonte de alimentação das cargas magnéticas do Sirius. A fonte é formada por associações em série e em paralelo de módulos de menor po-tência para que, em conjunto, possam atender às exigências requeridas de tensão e de corrente dos magnetos. Cada módulo é constituído de dois estágios, um de entrada e outro de saída, em que o segundo é o objeto de estudo deste trabalho. O estágio de saída é constituído por um conversor ponte completa associado a um filtro de terceira ordem. Inicialmente é feita a modelagem do estágio de saída e apresentado um modelo apropriado a uma quantidade genérica de módulos associados em série. Em seguida é feita a discretização da planta e o controle em espaço de estados. Para a alocação dos pólos do sistema em malha fechada é utilizado o Regulador Quadrático Linear Digital. Entretanto, quando módulos são associados, aumenta-se consideravelmente a ordem do sistema e torna-se inviável a medição de todos os estados da planta. Então, é proposto um observador ótimo de ordem reduzida para que este seja capaz de fornecer ao con-trolador os estados que não são medidos. A análise de estabilidade permitiu verificar a robustez do controle em conjunto com o observador de estados. Na associação de módulos em paralelo foram consideradas que as correntes da saída de cada módulo são parcelas do estado que corresponde à corrente das cargas magnéticas. Baseado nesta premissa e no controle feito para o arranjo de módulos em série, foi proposta uma estratégia de controle para o arranjo em paralelo. Os resultados em simulação, tanto para a configuração de módulos em série quanto em paralelo, permitem verificar os desempenhos dinâmicos do controlador e observador de estados. / This dissertation presents a proposal of a discrete-time state-feedback control law applied to the Sirius magnetic source power supply. In order to meet the magnets' required voltage and current levels the source is formed by series and parallel associa-tion of modular converters. Each module is made up of two stages, input and output, in which the later is addressed this work. The output stage is constituted by a full bridge converter associated with a third-order filter. Initially a mathematical model is obtained for a single module. This model is later extended to represent the connection of several modules in series. Then the plant is discretized and state feedback law is designed to control the system. The optimal technique Digital Linear Quadratic Regu-lator was used to place the closed-loop poles. However, when modules are associated, due the order of the system it becomes impracticable to measure all the states. Then an optimal reduced order observer is proposed to provide to controller the states that are not measured. An stability analysis is performed in order to verify the controller robustness. For the association of modules in parallel was considered that the output currents of each module are the parcels of the state corresponding to the current of the magnetic loads. Based on this premise and in the previously control design for the series modules association, is proposed a control topology for the parallel arrange-ment. Simulation results were obtained, for the both configuration of modules series and parallel, and the performances of the controller and state-observer were verified.
25

Apports des systèmes d'information à l'exploitation des réseaux de voies rapides. Le cas du réseau d'Ile-de-France

Zhang, Ming-Yu 11 January 1995 (has links) (PDF)
La présente recherche pluridisciplinaire a pour objectif principal d'analyser et d'évaluer de nouvelles potentialités de l'amélioration du fonctionnement des réseaux de voies rapides (RVR) avec leur maillage progressif et en particulier avec le développement des systèmes d'information des usagers. Cette recherche s'appuie principalement sur le cas concret du RVR d'Ile-de-France, représentatif par sa complexité structurelle et par les problèmes rencontrés lors de son exploitation et notamment ceux liés à la mise en œuvre opérationnelle du système d'exploitation : SIRIUS. L'examen de l'approche d'exploitation de ce réseau révèle deux problèmes majeurs qui sont au cœur de l'amélioration du fonctionnement des RVR : celui du manque d'outils adaptés et celui de l'organisation des acteurs. Partant de ces deux constats, notre recherche s'est focalisée sur deux axes : - développement, analyse, validation et prospective des outils d'exploitation, - analyse des aspects organisationnels et éléments de réflexion pour la définition de politiques d'exploitation. Cette recherche a consacré beaucoup d'effort au développement des outils et à l'élaboration des procédures pour la maîtrise du recueil automatique des données (RAD). Un enseignement de notre travail est d'avoir montré que, pour les systèmes d'exploitation comme SIRIUS, il s'agit là d'un aspect essentiel. L'approche de la détection automatique des bouchons (DAB) développée permet leur détection systématique et quasi instantanée, avec un taux de fausses alarmes raisonnable. L'application de cette approche de DAB devrait assurer une information fiable sur les encombrements. De manière générale, la maîtrise du RAD ouvre la voie à la prestation de différents niveaux de services dont l'impact en matière d'exploitation routière doit encore faire l'objet d'évaluations complémentaires. Parallèlement, nous démontrons que cette maîtrise - et plus généralement, celle de l'exploitation des RVR - dépend des réponses apportées à certains problèmes d'organisation. Dans un contexte multi-acteurs, il est nécessaire de favoriser au maximum la coopération, mais il faut également tenir compte des exigences d'autonomie de chaque acteur pour améliorer les performances d'ensemble du système socio-technique d'exploitation des RVR. Des propositions concrètes, visant à une approche globale des problèmes d'exploitation des RVR, sont formulées en ce sens.

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