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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

Projeto e análise estrutural de haste femoral de implante de quadril em material compósito polimérico / Design and structural analysis of hip implant femoral stem in polymeric composite materials

Geraldo Dantas Silvestre Filho 06 October 2006 (has links)
Neste trabalho propõe-se o projeto e a análise estrutural de uma haste femoral de implante de quadril em material compósito polimérico. No trabalho, realizaram-se algumas etapas com a finalidade de obter parâmetros confiáveis de comportamento do material, visando à consistência dos resultados numéricos e experimentais. Primeiramente, faz-se um levantamento bibliográfico sobre o comportamento mecânico dos materiais compósitos poliméricos reforçados, como também dos critérios de falha existentes para este tipo de material. Em seguida, apresentam-se as etapas experimentais com a descrição dos procedimentos de fabricação dos corpos-de-prova e os resultados obtidos a partir dos ensaios quase-estáticos de tração do poliuretano derivado de óleo de mamona. A etapa seguinte foi desenvolver um dispositivo de ensaio monotônico quase-estático para a haste femoral em poliuretano com o objetivo de levantar a curva força-deslocamento seguindo as especificações das normas ISO 7206-3 e ISO 7206-4. Com base nos resultados experimentais obtidos, foi possível propor um reforço estrutural, na forma de tubo, na haste femoral em poliuretano e adotar uma análise de falha progressiva para determinar o seu comportamento mecânico. Para esta finalidade foi implementado um modelo de material em sub-rotina FORTRAN, compilada em conjunto com um programa de elementos finitos (ABAQUS). Concluiu-se, que o modelo de material implementado e o reforço estrutural proposto para a haste femoral traz contribuições inovadoras, visto que se pode prever com mais precisão o comportamento mecânico da haste femoral reforçada com o tubo em material compósito polimérico. / A design and structural analysis of a femoral stem using a polymeric composite material is proposed in this work. The work had some steps in order to achieve trusty parameters for the material behavior aiming the consistence of numerical and experimental results. In the first step, a bibliographic review of mechanical behavior of reinforced polymeric composite materials as well as failure criterion was done. Following experimental steps are presented with specimen manufacturing procedure description and the results obtained from quasi-statics tension tests of polyurethane derivated from castor oil. The next step was the development of a monotonic quasistatic test device for the polyurethane femoral stem aiming to determine the forcedisplacement curve according to ISO 7206-3 and ISO 7206-4 standards. Considering the experimental results obtained it was possible to propose a structural reinforcement, which consists on a tube, in the polyurethane femoral stem and to adopt a progressive failure analysis in order to determine its mechanical behavior. A material model using FORTRAN sub-routine was developed and compiled joint with a finite element program (ABAQUS). The conclusion is that the model developed and the structural proposed reinforcement for the femoral stem bring innovation for this contribution once it is possible to preview accurately the mechanical behavior of the reinforced femoral stem with tube in polymeric composite material.
32

Comportamento operacional de elementos sulcadores de fertilizante em função da distância dos mesmos para o mecanismo de corte / Operating performance of elements fertilizer furrowers in the function of the distance for the coulter

Francetto, Tiago Rodrigo 25 April 2017 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective was to determine the effect of longitudinal distance between coulters and furrow openers about the operational performance of these associations working in different forward speeds, with regard to the energy requeriment and the amount of furrow, with the purpose of identifying the integration mechanism/regulation that presents the lowest energy consumption without compromising the quality of the furrow. This was carried out in an agricultural area located in the municipality of Santa Maria (Rio Grande do Sul), belonging to Universidade Federal de Santa Maria. The soil of the experimental area was classified as Ultisol and sandy. The experiment was composed of 24 combinations of treatments, in a factorial scheme of 2x3x4. These were composed by the interaction of the factors groove opening mechanisms (hoe furrow opener and mismatched double discs), longitudinal distance from center to center of coulter and furrowers (0,50,1,0 e 1,50 m) and forward speeds (1,11, 1,67, 2,22 e 2,78 m s-1). The variables responses of the performance of the mechanisms associations were obtained directly or indirectly, through the application of different methods by different tools. After the acquisition of the data, they were submitted to statistical analysis of variance and verified the significance of the factors through the F test. In addition, a mathematical analysis of the instantaneous rate of change, with the use of the differential calculus. The furrow, distance and velocity factors had a statistically significant influence on the primary performance variables resulting from instrumentation, except the distance factor on the slipping of the driving wheels. For the variables of soil mobilization, the furrow factor provided a significant change in all, while the distance factor significantly modified only the raised area and the maximum furrow depth. Already the velocity, interfered significantly in the latter and in the area of mobilized soil. In addition, in the secondary variables, the modification of the furrow and speed factors did not provide significant change only in the variable soil swelling, while the distance did not change the specific fuel consumption. The traction, the hourly consumption and the skating were higher for the configurations that employ the hoe furrow opener, present greater distance and work at higher speeds. The distance did not modify the mobilized area, the width and the depth of the furrow, and the reduction of this reduced the elevated area. The use of lower speeds and distances provides greater efficiency in the use of traction per unit of depth and of soil mobilized for both furrowers. / O objetivo foi determinar o efeito da distância longitudinal entre disco de corte e sulcador de fertilizante sobre o desempenho operacional destas associações trabalhando em diferentes velocidades de deslocamento, no que diz respeito ao requerimento energético e a qualidade de sulco, com o propósito de identificar a integração mecanismo/regulagem que apresente o menor consumo energético sem comprometer a qualidade do sulco. Este foi realizado em área agrícola situada no município de Santa Maria (Rio Grande do Sul), pertencente à Universidade Federal de Santa Maria. O solo da área experimental foi classificado como Argissolo e textura franca. O experimento foi composto por 24 combinações de tratamentos, em um esquema fatorial de 2x3x4. Estes foram compostos pela interação dos fatores mecanismos de abertura de sulco (haste sulcadora e discos duplos desencontrados), distância longitudinal de centro a centro do mecanismo de corte e dos sulcadores (0,50, 1,0 e 1,50 m) e velocidades de deslocamento (1,11, 1,67, 2,22 e 2,78 m s-1). As variáveis respostas do desempenho das associações de mecanismos foram obtidas de forma direta ou indireta, através da aplicação de diferentes métodos por distintas ferramentas. Após a aquisição dos dados, os mesmos foram submetidos à análise estatística de variância e verificado a significância dos fatores através do teste F. Além disso, foi realizada uma análise matemática da taxa de variação instantânea, com o uso do cálculo diferencial. Os fatores sulcador, distância e velocidade apresentaram influência estatisticamente significativa sobre as variáveis de desempenho primárias oriundas da instrumentação, exceto o fator distância sobre o patinamento dos rodados motrizes. Para as variáveis de mobilização do solo, o fator sulcador proporcionou alteração significativa em todas, enquanto que o fator distância modificou significativamente apenas a área elevada e a profundidade máxima do sulco. Já a velocidade, interferiu significativamente nesta última e na área de solo mobilizada. Ademais, nas variáveis secundárias, a modificação dos fatores sulcador e velocidade não proporcionaram alteração significativa apenas na variável empolamento, enquanto que a distância não modificou o consumo específico de combustível. O esforço tratório, o consumo horário e o patinamento, foram mais elevados para as configurações que empregam a haste sulcadora, apresentam maior distância e trabalham em maiores velocidades. A distância não modificou a área mobilizada, a largura e a profundidade do sulco, sendo que a redução desta diminuiu a área elevada. O emprego de velocidades e distâncias menores propiciou maior eficiência no uso da tração por unidade de profundidade e de solo mobilizada para ambos os sulcadores.
33

現代台湾における対外経済政策を巡る政治過程 / ゲンダイ タイワン ニオケル タイガイ ケイザイ セイサク オ メグル セイジ カテイ

吉田 知史, Tomofumi Yoshida 19 September 2020 (has links)
本研究では李登輝政権以降の台湾における対外経済政策の変化メカニズムを検討した。構造レベルからの入力である米国の台湾政策と台湾企業は、台湾政府に対して対中投資規制の緩和と直航便の開設を求めてきた。これに対して台湾政府は、強固な抵抗・不安定な抵抗・構造への順応という3つの反応をしてきた。これを決定付けるのは、政権基盤の強弱・政権の重心・政権基盤の強化策というユニットレベルの3つの変数であることを明らかにした。 / This study examines the mechanism of changing foreign economic policy of Taiwan. The U.S. Taiwan policy and Taiwanese businesses, which were the inputs from the structure level, had demanded Taiwanese government to ease restrictions regarding investment to PRC and to introduce direct cross-strait link. Taiwanese government's reactions can be divided into three, which are 'Strict Resistance,' 'Partial Resistance,' and 'Accommodation to Structure.' This study shows that 'Strangeness of Administration's Political Power Base,' 'Administration's Direction,' and 'Way of Enforcing Administration's Political Power Base,' which are unit level variables, had determined which reaction the government would take. / 博士(政治学) / Doctor of Political Science / 同志社大学 / Doshisha University
34

Asynchronous Event-Feature Detection and Tracking for SLAM Initialization

Ta, Tai January 2024 (has links)
Traditional cameras are most commonly used in visual SLAM to provide visual information about the scene and positional information about the camera motion. However, in the presence of varying illumination and rapid camera movement, the visual quality captured by traditional cameras diminishes. This limits the applicability of visual SLAM in challenging environments such as search and rescue situations. The emerging event camera has been shown to overcome the limitations of the traditional camera with the event camera's superior temporal resolution and wider dynamic range, opening up new areas of applications and research for event-based SLAM. In this thesis, several asynchronous feature detectors and trackers will be used to initialize SLAM using event camera data. To assess the pose estimation accuracy between the different feature detectors and trackers, the initialization performance was evaluated from datasets captured from various environments. Furthermore, two different methods to align corner-events were evaluated on the datasets to assess the difference. Results show that besides some slight variation in the number of accepted initializations, the alignment methods show no overall difference in any metric. Overall highest performance among the event-based trackers for initialization is HASTE with mostly high pose accuracy and a high number of accepted initializations. However, the performance degrades in featureless scenes. CET on the other hand shows mostly lower performance compared to HASTE.

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