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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.
31

Estudo da representação numérica do comportamento mecânico de músculos esqueléticos sujeitos à combinação de diferentes tipos de contrações / A study of the numeric skeletal muscle mechanical representation subjected to different contractions

Lagemann, Frederico January 2015 (has links)
Esta dissertação apresenta um estudo da caracterização numérica do comportamento mecânico de um músculo esquelético estriado sujeito à combinação de diferentes contrações. A partir dos mecânismos fisiológicos da contração do tecido muscular esquelético, são apresentadas as principais características da produção de força do músculo em diferentes tipos de contrações (isométrica, concêntrica, excêntrica) e suas combinações. A representação numérica da resposta mecânica do músculo esquelético foi investigada por diferentes autores. Dos diversos modelos encontrados na literatura, alguns foram escolhidos para a continuidade deste estudo, segundo sua capacidade representativa e facilidade de implementação em métodos numéricos de solução para grandes deformações. Os modelos disponíveis na literatura foram implementados e avaliados para diferentes sequências de contrações, sendo também realizado um ajuste de parâmetros para dados experimentais de contrações isométricas e isométricas-excêntricas-isométricas. Nenhuma das propostas avaliadas apresentou resultados satisfatórios. A principal deficiência dos modelos foi a incapacidade de reproduzir a dependência do histórico de carregamentos, ou seja, da combinação de contrações. Desta maneira, uma nova proposta de modelo constitutivo foi desenvolvida e implementada para testes uniaxiais e em um código de elementos finitos para testes tridimensionais. A partir destas implementações, foram executados testes numéricos para diferentes sequências de contrações, avaliando a capacidade representativa do modelo proposto neste trabalho. O modelo proposto apresentou bons resultados para contrações isométricas e a combinação de contrações com diferentes níveis de alongamento, ou encurtamento, a uma mesma velocidade. A principal contribuição deste modelo é a capacidade de representar a resposta associada à fadiga muscular e o ganho, ou perda de força, observados experimentalmente. / This work present a striated skeletal muscle numerical characterization subjected to different contractions. From the physiological contraction mechanism of the skeletal muscle tissue the force produced in different kinds of contraction (isometric, concentric and eccentric), and their combination, are presented. The numerical representation of these response was investigated by different authors. From the diverse models found in literature, some were selected to be studied according to their representation capability and the implementation ease in numerical methods for large strains. The models available in literature were implemented and evaluated for different contractions combinations and a parameter identification for experimental results of two isometric contraction and a isometric-eccentric-isometric contraction. None of the proposed models presented satisfactory results. The main deficiency of these models were the incapability of reproducing the loading history dependence, in other words, the contraction combination. In this way, a new material model was proposed and implemented to uniaxial and tridimensional finite element method tests. From these, different contractions sequences evaluated the proposed model representation capabilities. The proposed model present good results to isometric contraction, as well as contraction combination with different stretch, or shortening, level in the same speed. The main contribution of this model is the capability of represent the the response associated to the muscle fatigue and the force gain or loss, experimentally observed.
32

Redes complexas: novas metodologias e modelagem de aquisição de conhecimento / Complex Networks: New methodologies and knowledge acquisition modeling

Filipi Nascimento Silva 17 December 2009 (has links)
Estudos em redes complexas têm ganhado cada vez mais atenção devido ao seu potencial de representação simples de modelos complexos em diversas áreas de conhecimento. A obtenção de modelos quantitativos que representem fenômenos observados da natureza, assim como o desenvolvimento de metodologias de caracterização de redes complexas, tornaram-se essenciais para a compreensão e desenvolvimento de pesquisas com essas estruturas. Este trabalho tem como objetivo desenvolver e estudar alguns métodos recentes, usados para a caracterização de redes complexas, explorando-os no contexto da modelagem de conhecimento. Para isso, duas redes complexas foram geradas, uma rede de colaboração de pesquisadores da USP e outra obtida a partir do banco de dados de artigos da Wikipédia, considerando apenas aqueles da categoria de teoremas matemáticos. As medidas concêntricas, que foram recentemente formalizadas, são exploradas e aplicadas às redes descritas, assim como para diversos modelos teóricos, fornecendo informações muito relevantes sobre a topologia dessas redes. Resultados ainda mais interessantes são obtidos pela caracterização dos vértices da rede de colaboração, que revelam padrões de interdisciplinaridade entre as diferentes áreas do conhecimento. Um modelo de aquisição de conhecimento também foi proposto, aplicando a utilização de simulações de múltiplos agentes interagentes que caminham por uma rede complexa segundo uma heurística auto-esquivante. Resultados dessas simulações, realizadas para a rede da Wikipédia e outros modelos teóricos, mostram que certas configurações de parâmetros e de redes apresentam melhor desempenho na aquisição do conhecimento, com a rede de teoremas apresentando o pior deles. Entretanto, diferentemente do que era esperado, a variação da memória dos agentes pouco influência a velocidade de aquisição de conhecimento dos agentes. A freqüência de acesso dos vértices pelos agentes também foi determinada e explorada superficialmente. Diversos softwares foram desenvolvidos para uso neste projeto de mestrado, dentre eles destaca-se o visualizador 3D, que se tornou indispensável para a análise das contribuições das outras propriedades apresentadas. / Studies of complex networks have gained increasing research interest in recent years, in part due to its potential for simple representation of complex systems in various fields of science. The needs of quantitative models representing observed phenomena, as well the development of methods for the characterization of complex networks, is a essential matter for the development and understanding of scientific researches exploring such structures. This work aims to develop and study some new methods for the characterization of complex networks, exploring them in the context of knowledge modeling. Initially, two complex networks were developed, a collaborative network of researchers from the Universidade de Sao Paulo and the other obtained from the database of Wikip´edia articles, considering only those strict related to mathematical theorems. The recently formalized concentric measurements are explored and applied to the described networks, as well to other several theoretical models, providing much more information about the topology of these networks than by the use of traditional measurements. Even more interesting results are obtained by the characterization of the vertices of the collaboration network, which reveal patterns of interdisciplinarity among the many fields of science. A model of knowledge acquisition has also been proposed by the use of simulations of multiple interacting agents walking through a complex network in self-avoiding trajectories. Results of those simulations, performed for the network of Wikipedia and other theoretical models shows that certain sets of parameters and networks perform better in the acquisition of knowledge, through the network of theorems presenting the worst of them. However, unlike what should be expected on the basis of intuition, the agents memories do not play much influence to the speed of acquisition of knowledge. The agent access frequencies of vertices was also been obtained and explored superficially in order to determine where the agents walk more ofen. Several softwares had been developed in this masters thesis project, among these, there is a complex network computational visualization tool, which had become indispensable for the many analysis of the contributions obtained by the use of the other described properties.
33

Estudo da representação numérica do comportamento mecânico de músculos esqueléticos sujeitos à combinação de diferentes tipos de contrações / A study of the numeric skeletal muscle mechanical representation subjected to different contractions

Lagemann, Frederico January 2015 (has links)
Esta dissertação apresenta um estudo da caracterização numérica do comportamento mecânico de um músculo esquelético estriado sujeito à combinação de diferentes contrações. A partir dos mecânismos fisiológicos da contração do tecido muscular esquelético, são apresentadas as principais características da produção de força do músculo em diferentes tipos de contrações (isométrica, concêntrica, excêntrica) e suas combinações. A representação numérica da resposta mecânica do músculo esquelético foi investigada por diferentes autores. Dos diversos modelos encontrados na literatura, alguns foram escolhidos para a continuidade deste estudo, segundo sua capacidade representativa e facilidade de implementação em métodos numéricos de solução para grandes deformações. Os modelos disponíveis na literatura foram implementados e avaliados para diferentes sequências de contrações, sendo também realizado um ajuste de parâmetros para dados experimentais de contrações isométricas e isométricas-excêntricas-isométricas. Nenhuma das propostas avaliadas apresentou resultados satisfatórios. A principal deficiência dos modelos foi a incapacidade de reproduzir a dependência do histórico de carregamentos, ou seja, da combinação de contrações. Desta maneira, uma nova proposta de modelo constitutivo foi desenvolvida e implementada para testes uniaxiais e em um código de elementos finitos para testes tridimensionais. A partir destas implementações, foram executados testes numéricos para diferentes sequências de contrações, avaliando a capacidade representativa do modelo proposto neste trabalho. O modelo proposto apresentou bons resultados para contrações isométricas e a combinação de contrações com diferentes níveis de alongamento, ou encurtamento, a uma mesma velocidade. A principal contribuição deste modelo é a capacidade de representar a resposta associada à fadiga muscular e o ganho, ou perda de força, observados experimentalmente. / This work present a striated skeletal muscle numerical characterization subjected to different contractions. From the physiological contraction mechanism of the skeletal muscle tissue the force produced in different kinds of contraction (isometric, concentric and eccentric), and their combination, are presented. The numerical representation of these response was investigated by different authors. From the diverse models found in literature, some were selected to be studied according to their representation capability and the implementation ease in numerical methods for large strains. The models available in literature were implemented and evaluated for different contractions combinations and a parameter identification for experimental results of two isometric contraction and a isometric-eccentric-isometric contraction. None of the proposed models presented satisfactory results. The main deficiency of these models were the incapability of reproducing the loading history dependence, in other words, the contraction combination. In this way, a new material model was proposed and implemented to uniaxial and tridimensional finite element method tests. From these, different contractions sequences evaluated the proposed model representation capabilities. The proposed model present good results to isometric contraction, as well as contraction combination with different stretch, or shortening, level in the same speed. The main contribution of this model is the capability of represent the the response associated to the muscle fatigue and the force gain or loss, experimentally observed.
34

Termofluidodinamica de sucos de frutas pseudoplasticos em dutos cilindricos e anulos concentricos / Thermo-fluid dynamics to pseudoplastic fruit juices in cilindrical ducts and concentric annuli

Gratão, Ana Carolina Amaral 17 April 2006 (has links)
Orientadores: Vivaldo Silveira Junior, Javier Telis Romero / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-06T15:00:42Z (GMT). No. of bitstreams: 1 Gratao_AnaCarolinaAmaral_D.pdf: 2034155 bytes, checksum: 7a7cc4a961cab6b38ae3dc5ee5f3f9d8 (MD5) Previous issue date: 2006 / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos
35

An Exploratory Study on the Use of Concentric Velocities in the Back Squat as a Monitoring Tool

Carroll, Kevin M., Christovich, Josh D., Bazyler, Caleb D., Fiolo, Nicholas J., Beckham, George K., Sato, Kimitake 01 December 2014 (has links)
Abstract available in the 9th Annual Coaches and Sport Science College .
36

The Effects of Different Set Configurations on Concentric Velocities in the Barbell Back Squat

Wong, Hanson 01 August 2020 (has links)
The purpose of this study was to determine if concentric velocities of lighter loads of could be augmented if they are performed heavier working sets. Twelve trained males with experience in the barbell back squat performed a 5RM and completed two separate squat training session conditions that consisted of three sets of five repetitions with 85% of their 5RM. Both conditions differed in the placement of a reduced-load set that was either performed after the working sets or during the warm-up period. No significant differences were observed in the working set MCVs in both conditions. Additionally, no significant differences were observed amongst MCVs in the Down Set and equivalent warm-up set loads. The results of this study suggest that postactivation potentiation may not occur using a similar set-load scheme.
37

Visible and near-infrared airglow structures in the mesosphere and the lower thermosphere observed by space-borne instruments / 宇宙空間からの観測による中間圏および下部熱圏における可視近赤外域大気光の構造についての研究

Akiya, Yusuke 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18798号 / 理博第4056号 / 新制||理||1583(附属図書館) / 31749 / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 齊藤 昭則, 教授 田口 聡, 教授 余田 成男 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
38

Prediction of Intensity Change Subsequent to Concentric Eyewall Events

Mauk, Rachel Grant 21 December 2016 (has links)
No description available.
39

The Free Radical Polymerization of Methyl Methacrylate to High Conversions

Balke, Thomas Stephen January 1972 (has links)
<p>This dissertation describes an investigation into the free radical batch polymerization of methyl methacrylate to high conversion. The overall objective was to develop a kinetic model to accurately predict conversion and molecular weight distribution for the polymerization. The dissertation is divided into three self-contained parts.</p> <p>Part I describes the development and testing of the kinetic model. New gel permeation chromatograph (GPC) data interpretation methods (developed in Part I I), the free volume concept of diffusion theory, and newly obtained isothermal kinetic data, are combined with computer implemented optimization techniques, to show that classical kinetics apply to high conversions.</p> <p>Part II details the development of three new GPC interpretation techniques. The two most recent are evaluated in Part I.</p> <p>The third has been used by other workers. Other interpretation methods are also evaluated and discussed. Part I I I describes the development of a high shear concentric cylinder viscometer and its use with Newtonian standards. This is a prelude to future studies in polymer rheology and polymerization under shear conditions.</p> / Doctor of Philosophy (PhD)
40

Petrogenesis and Concentric Zonation of the Belchertown Intrusive Complex, West-Central Massachusetts

Van Wagner, Karen June 11 July 2017 (has links) (PDF)
The Belchertown Intrusive Complex is a ~164 km2 Devonian pluton that intruded Paleozoic metasedimentary and metavolcanic rocks in west-central Massachusetts. Intrusion of the pluton was synchronous with Acadian deformation (Ashwal, 1974). The complex is concentrically zoned, with a core of orthopyroxene-biotite monzodiorite, a middle zone of clinopyroxene-hornblende-biotite granodiorite, and an outermost zone of hornblende-biotite granodiorite. Zoning from a more to less hydrous mineral suite from the outside to the inside of the pluton led Ashwal (1974) to suggest that metamorphic hydration most strongly affected the outermost zones of the complex. Basaltic inclusions occur most commonly near the edges of the pluton. Many of these inclusions preserve textures suggestive of mafic-felsic magma interaction. The abundance of basaltic enclaves on the edges of the complex may suggest a bowl-shaped structure, with lower more mafic-dominated rocks exposed on the edges of the complex. Bulk rock major element analyses of granitoids, basalts and gabbros, and diorites from all zones of the complex show that intermediate samples, regardless of zone, plot on a mixing line between mafic and felsic end members, supporting a model in which mafic and felsic magmas may have mingled and mixed. Trace element analyses of intermediate-composition samples are similar across the entire complex, with enrichment in large ion lithophile elements and a pronounced Nb trough. In contrast, trace element concentrations in both the mafic rocks (basaltic enclaves and gabbroic inclusions), and in the granitoids, show considerable variation. The diversity of composition within both the mafic and felsic end-members suggests that either fractionation or differing degrees of partial melting of source rocks may account for these compositional ranges. Sanukitoids comprise a majority of the inner zone, and point to the mixing of parental melts at depth in a subduction tectonic regime as a likely model of petrogenesis for the complex.

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