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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.
91

Finite Element Modeling of Extensor Carpi Radialis Longus and Brevis: Computation of Architectural Parameters and Physiological Cross Sectional Area as Whole Muscles and Regions

Ravichandiran, Kajeandra 15 February 2010 (has links)
Physiological cross sectional area (PCSA) is used to compare force-producing capabilities of skeletal muscles. PCSA has been defined as the summation of the cross sectional area of the fiber bundles composing the muscle. As PCSA cannot be measured directly from a specimen, a formula requiring averaged muscle architectural parameters has traditionally been used. The purpose of this study was to develop a finite element method (FEM) to calculate PCSA of extensor carpi radialis longus (ECRL) and brevis (ECRB) directly from digitized fiber bundle data obtained throughout the volume of the muscle and to compare the PCSAs calculated using the FEM and formula methods. Differences were found between the FEM and formula method for both muscles. The FEM provides an approach that takes into account architectural variances while minimizing the need for averaged architectural parameters.
92

Finite Element Modeling of Extensor Carpi Radialis Longus and Brevis: Computation of Architectural Parameters and Physiological Cross Sectional Area as Whole Muscles and Regions

Ravichandiran, Kajeandra 15 February 2010 (has links)
Physiological cross sectional area (PCSA) is used to compare force-producing capabilities of skeletal muscles. PCSA has been defined as the summation of the cross sectional area of the fiber bundles composing the muscle. As PCSA cannot be measured directly from a specimen, a formula requiring averaged muscle architectural parameters has traditionally been used. The purpose of this study was to develop a finite element method (FEM) to calculate PCSA of extensor carpi radialis longus (ECRL) and brevis (ECRB) directly from digitized fiber bundle data obtained throughout the volume of the muscle and to compare the PCSAs calculated using the FEM and formula methods. Differences were found between the FEM and formula method for both muscles. The FEM provides an approach that takes into account architectural variances while minimizing the need for averaged architectural parameters.
93

Monitoramento de perfis lineares / Monitoring of linear profiles

Viviany Leão Fernandes 29 April 2009 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Uma das ferramentas básicas no controle estatístico de processos são os gráficos de controle de Shewhart, úteis no monitoramento das características-chave da qualidade nos processos de produção. Este monitoramento pode ser feito através de gráficos de controle univariados ou multivariados, quando a característica de qualidade é representada, respectivamente, por uma variável aleatória univariada ou multivariada. Em alguns casos, a qualidade pode ser representada por algum tipo de perfil, uma relação linear ou não-linear entre suas características. Este trabalho é dedicado ao estudo da fase II de gráficos de controle, ao monitoramento de uma variável, em um processo de produção, que é representada por um perfil linear, e os coeficientes de regressão são estimados pelo método de mínimos quadrados ordinários e pelo filtro de Kalman. Utiliza-se o gráfico de controle 2 c para o monitoramento dos parâmetros, intercepto e coeficiente de inclinação, do modelo de regressão linear simples. É proposto a aplicação das estimativas do filtro de Kalman ao gráfico de controle 2 c e também o estudo da eficiência deste gráfico com tais estimativas, bem como, a comparação com as estimativas obtidas pelo método de mínimos quadrados ordinários. Através de uma métrica construída com as estimativas do filtro de Kalman e com as estimativas do método de mínimos quadrados ordinários, compara-se o desempenho do gráfico de controle 2 c e verifica-se que este é mais rápido na detecção de mudanças nos parâmetros do modelo do processo quando suas estimativas são geradas pelo filtro de Kalman do que pelo método de mínimos quadrados ordinários. / Shewhart chart is a fundamental tool in statistical process control, and is useful in the monitoring of key quality characteristics in production processes. That monitoring can be done by univariate or by multivariate control charts, when the quality characteristic can be represented by a random variable or random vector. There are however certain cases where the quality can be represented by a profile, linear or nonlinear, between its characteristics. This work is dedicated to the control strategy for Phase II, to the monitoring of variables in a production process following a linear profile and the regression coefficients estimated by least squares and by Kalman filter. Our aim is to compare the performance of the 2 c control chart when the parameters of the model are estimated by those alternative techniques. Control chart 2 c has been used to monitor parameters of simple linear regression model. It has been proposed to apply the Kalman Filter estimates in the control chart 2 c and to analyse the efficiency of this chart considering such estimates, as well as, the comparison with the least squares estimates. The performance of this chart has been compared by those two techniques of estimation and has been confirmed that the control chart 2 c is more efficient when combined with the Filter Kalman estimates than with the least squares estimates.
94

Um modelo de duas escalas da resposta elétrica de tecido muscular induzida por ativação de mastócitos / 2-Scales modelling electrical response from muscular tissue induced by mast cells activation.

Esbel Tomás Valero Orellana 28 February 2010 (has links)
O estudo dos mecanismos que desencadeiam as reações alérgicas é um tema de grande interesse científico na atualidade. A anafilaxia, reação alérgica sistêmica severa, tem ocupado um lugar de destaque nas pesquisas. Diferentes experimentos em laboratório, tanto in vivo quanto in vitro, assim como diferentes modelos matemáticos baseados nos resultados experimentais, têm procurado investigar a participação ou não dos mastócitos nesse mecanismo. No entanto, os resultados obtidos não são conclusivos, dividindo a comunidade científica em dois grupos: os que consideram determinante o papel dos mastócitos responsáveis pela liberação de histamina e os que consideram que a histamina não é o neurotransmissor determinante na reação anafilática. Trabalhos anteriores propuseram modelos diferenciais para simular processos relacionados com a reação anafilática na escala celular para o mecanismo de geração de potencial na membrana das células. Mais recentemente foi proposto, a nível de tecido, um modelo probabilístico para simular a resposta in vitro a antígenos. A nível de organismo têm sido propostos modelos de multi compartimentos para a cinética da histamina no fluido sanguíneo. Contudo, nenhum trabalho até o momento abordou a construção de um modelo capaz de descrever os processos que participam no mecanismo de reação anafilática nas diversas escalas. Neste trabalho propomos um modelo que integra as escalas celular e do tecido, que permite modelar experimentos in vitro, e que pode ser estendido para escala do organismo incluindo o fluxo sanguíneo para modelar experimentos in vivo. O modelo proposto integra o mecanismo de resposta elétrica a nível celular com o processo de reação-difusão da histamina e dos antígenos no tecido, considerando o mecanismo de reação mediado por mastócitos. Para integrar as duas escalas propomos uma relação constitutiva baseada em resultados experimentais da resposta mecânica (contração do tecido) a estímulos elétricos. Este modelo permite o desenho de novos experimentos especificamente direcionados ao estudo da reação anafilática, indicando os parâmetros a serem estimados. Utilizando-se o modelo proposto, foram realizadas simulações numéricas para uma ampla faixa de variação dos parâmetros visando identificar domínios com diferentes comportamentos do modelo. Uma análise dos resultados obtidos baseada em parâmetros adimensionais é apresentada. / The study of the mechanisms that set off allergic reactions is being a subject of great scientific interest. Anaphylaxis, severe systemic allergic reaction, occupies a prominence place in researches. Different laboratory experiments, in vivo as well as in vitro, and also different mathematical models based on experimental results, tries to investigate if mast cells takes part in those mechanisms or not. However, the obtained results are inconclusive, dividing the scientific community in two groups: one considering that mast cells have a prime role in releasing histamine, and another one which considers that histamine is not the determinative neurotransmitter in the anaphylactic reaction. Previous works proposed differential models to simulate processes related to anaphylactic reactions in the cellular scale for the cell membrane potential generation mechanism. More recently, it has been proposed a probabilistic model, in the tissue scale, to simulate an in vitro antigen response. In the organism level scale, multi-compartimental models have been proposed for the kinetics of histamine in the blood. Nevertheless, no work, until now, has proposed the construction of a model that is able to describe the processes that participate in the mechanism of anaphylactic reaction in different scales. In this work, a model is proposed that integrates the cellular and the tissue scales, allowing to model in vitro experiments, being capable to be extended to the organism scale by the inclusion of the blood flow to model in vivo experiments. The proposed model couples the electric response in the cellular level with the reaction-diffusion of histamine and antigens in the tissue, considering the reaction mechanism mediated by the mast cells. To integrate these two scales, it is proposed here a constitutive relation based on experimental results for the mechanical response (tissue contraction) to electric stimulus. This model allows to design experiments specifically related to the anaphylaxis reaction, indicating the parameters that should be estimated. With this model, numerical simulations have been performed for a wide variation range of the parameters to identify the different domains of the model. A dimensionless parameter based analysis is presented for the obtained results.
95

Monitoramento de perfis lineares / Monitoring of linear profiles

Viviany Leão Fernandes 29 April 2009 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Uma das ferramentas básicas no controle estatístico de processos são os gráficos de controle de Shewhart, úteis no monitoramento das características-chave da qualidade nos processos de produção. Este monitoramento pode ser feito através de gráficos de controle univariados ou multivariados, quando a característica de qualidade é representada, respectivamente, por uma variável aleatória univariada ou multivariada. Em alguns casos, a qualidade pode ser representada por algum tipo de perfil, uma relação linear ou não-linear entre suas características. Este trabalho é dedicado ao estudo da fase II de gráficos de controle, ao monitoramento de uma variável, em um processo de produção, que é representada por um perfil linear, e os coeficientes de regressão são estimados pelo método de mínimos quadrados ordinários e pelo filtro de Kalman. Utiliza-se o gráfico de controle 2 c para o monitoramento dos parâmetros, intercepto e coeficiente de inclinação, do modelo de regressão linear simples. É proposto a aplicação das estimativas do filtro de Kalman ao gráfico de controle 2 c e também o estudo da eficiência deste gráfico com tais estimativas, bem como, a comparação com as estimativas obtidas pelo método de mínimos quadrados ordinários. Através de uma métrica construída com as estimativas do filtro de Kalman e com as estimativas do método de mínimos quadrados ordinários, compara-se o desempenho do gráfico de controle 2 c e verifica-se que este é mais rápido na detecção de mudanças nos parâmetros do modelo do processo quando suas estimativas são geradas pelo filtro de Kalman do que pelo método de mínimos quadrados ordinários. / Shewhart chart is a fundamental tool in statistical process control, and is useful in the monitoring of key quality characteristics in production processes. That monitoring can be done by univariate or by multivariate control charts, when the quality characteristic can be represented by a random variable or random vector. There are however certain cases where the quality can be represented by a profile, linear or nonlinear, between its characteristics. This work is dedicated to the control strategy for Phase II, to the monitoring of variables in a production process following a linear profile and the regression coefficients estimated by least squares and by Kalman filter. Our aim is to compare the performance of the 2 c control chart when the parameters of the model are estimated by those alternative techniques. Control chart 2 c has been used to monitor parameters of simple linear regression model. It has been proposed to apply the Kalman Filter estimates in the control chart 2 c and to analyse the efficiency of this chart considering such estimates, as well as, the comparison with the least squares estimates. The performance of this chart has been compared by those two techniques of estimation and has been confirmed that the control chart 2 c is more efficient when combined with the Filter Kalman estimates than with the least squares estimates.
96

Otimização do atendimento médico-hospitalar emergencial utilizando sistema a eventos discretos / Optimization of emergency medical-hospital care using discrete event system

Santos, Luciano Eduardo Braga dos 17 June 2016 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2016-10-17T18:54:20Z No. of bitstreams: 2 Dissertação - Luciano Eduardo Braga dos Santos - 2016.pdf: 4527753 bytes, checksum: 8db193f1cca4949ecdcfe2e93d9399f2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2016-10-18T17:16:29Z (GMT) No. of bitstreams: 2 Dissertação - Luciano Eduardo Braga dos Santos - 2016.pdf: 4527753 bytes, checksum: 8db193f1cca4949ecdcfe2e93d9399f2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-18T17:16:29Z (GMT). No. of bitstreams: 2 Dissertação - Luciano Eduardo Braga dos Santos - 2016.pdf: 4527753 bytes, checksum: 8db193f1cca4949ecdcfe2e93d9399f2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-06-17 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / This work prop oses numerical metho d of simulation and optimization of waiting time in queues in hospital emergency. The case study is carried out in private hospital in the city of Goiania, Goias/Brazil. It is used to mo del discrete event systems as computational simulator and two optimization heuristics: the Brute Force algorithm and Genetic Algorithm. The optimization results are compared with the directives found in Resolution CFM 2077/2014, in an attempt to adapt the system to this resolution. With the results, it is observed that the simulation metho d and optimization metho ds are efficient to minimize queues at hospital emergency system. / Este trabalho prop˜oe m´eto do num´erico de simula¸c˜ao e otimiza¸c˜ao do temp o de esp era nas filas da emergˆencia hospitalar. O estudo de caso ´e realizado em hospital da rede particular, do munic´ıpio de Goiˆania. Utiliza-se a mo delagem de sistemas a eventos discretos como simulador computacional e dois m´eto dos heur´ısticos de otimiza¸c˜ao: o Algoritmo de For¸ca Bruta e o Algoritmo Gen´etico. Os resultados da otimiza¸c˜ao s˜ao comparados com as diretivas encontradas na Resolu¸c˜ao CFM no 2077/2014, na tentativa de adequar o sistema a esta resolu¸c˜ao. De posse dos resultados obtidos, observa-se que o m´etodo de simula¸c˜ao e os m´etodos de otimiza¸c˜ao s˜ao eficientes para minimiza¸c˜ao de filas em sistema de emergˆencia hospitalar.
97

Modélisation atomique de nanoparticules métalliques sur substrats carbonés et graphène épitaxié sur métaux / Atomistic modeling of metallic nanoparticles on carbonaceous substrates and epitaxial graphene on metals

Förster, Georg Daniel 30 September 2015 (has links)
Les applications des nanoparticules métalliques nécessitent des assemblées monodisperses et stables sur un substrat tel que le graphène ou le graphite. Le graphène épitaxié sur métal (GEM) est étudié, car il facilite l'auto-organisation des adsorbats. La différence entre les mailles du graphène et du métal conduit à un effet de moiré contenant certaines régions favorables de l'adsorption. Ce travail est consacré surtout aux systèmes Ru-C et Pt-C où nous nous sommes intéressé au substrat du GEM nu, des agrégats y etant deposés et des agrégats métalliques sur graphite. Les potentiels d'ordre de liason permettent de mener des études en dynamique moléculaire sur des systèmes de taille réaliste à température finie. Dans le cas du système Pt-C une paramétrisation est disponible dans la littérature. Cependant, pour le système du Ru-C une paramétrisation sur la base de données DFT était nécessaire. Ce modèle atomistique néglige les forces de dispersion importantes pour des milieux étendus. Basé sur les modèles de Grimme, nous avons développé une description implicite tenant compte de la structure du substrat et son extension semi-infinie. De plus les effets d'écrantage importants pour des milieux métalliques sont pris en compte. Basé sur ce champ de force nous montrons des propriétés des adsorbats sur des substrats carbonés où nous évaluons le modèle de forces de dispersion. Grâce à des simulations de dynamique moléculaire, la stabilité des adsorbats et du graphène a été étudié dans le contexte de la dynamique vibrationnelle et de diffusion. En accord avec les expériences, la mobilité des adsorbats sur graphite s'avère élevée en comparaison avec des adsorbats sur GEM / Applications of metal nanoparticles require monodisperse and stable assemblies on a substrate such as graphene or graphite. Epitaxial graphene on metal (GOM) has attracted research interest because it contributes to the self-organisation of adsorbates. The difference in the lattice constants of graphene and metal leads to a moiré that contains certain regions that are favorable for adsorption. This work is mainly concerned with the Ru-C and Pt-C systems where we were interested in the bare substrate of GOM, adsorbates deposited thereon and metal clusters on graphite. Bond order potentials allow to carry out molecular dynamics studies for systems of realistic size and at finite temperature. In the case of the Pt-C, a parametrization is available in the literature. However, for Ru-C systems a custom parametrization effort based on data from electronic structure calculations was necessary. This atomistic model neglects long ranged dispersion forces that are important for adsorption phenomena on extended substrates. Based on the Grimme models, we developed an implicit description that takes the layered structure and the semi-infinite extension of the substrate into account. Also, screening effects that are important for metal materials are taken into account. Based on this force field, we show results concerning the properties of adsorbates on carbon substrates while evaluating the dispersion model. With the help of molecular dynamics simulations, the stability of adsorbates and graphene has been studied in the context of vibrational and diffusion dynamics. In agreement with experiments, the mobility of the adsorbates on graphite is high in comparison with adsorbates on GOM
98

Modeling Manifest and Latent Structures in a University: Understanding Resources and Dissent Dynamics

Zaini, Raafat Mahmoud 23 January 2017 (has links)
Using modeling and computer simulation, this research focuses on studying two different views to organizational design and their implications for performance in the context of academic institutions. One view represents the manifest structure that includes resources (students, faculty, administration, facilities, finances, partners, donors, etc.); the other view represents the latent structure that focuses on dissent. The dissertation addresses the following two questions; 1. What are the tangible dynamic interdependencies constituting the manifest structure within academic institutions and their impact on performance? 2. What is the impact of the latent structures composed of intangible organizational processes, especially dissent, on performance? The dissertation proposes generic system dynamics simulation models untangling the complexity of the topic by tackling various slices of the problem in separate papers. The models are based on three different theoretical frameworks addressing resources and their composition, dissent, and stakeholder engagement. It is observed that while both the manifest and the latent parts of the university organization impact its performance, the latent part, being invisible, is often ignored. In the long run, the influence of the latent part of the organization can slowly but seriously compromise intangible performances components like quality, reputation, and attractiveness. When the manifest part of the organization is dysfunctional, its tangible performance rapidly suffers. The damage control policies will often impact the latent organizational performance leading the institution into a vicious cycle. The presence of time delays in this framework may create an oscillatory behavior that might modulate a growth or decline trend. Performance measures addressing intangible performance components must be factored into the organizational design since faculty, students, and other stakeholders are not only driven by financial rewards, but also by the organizational environment. The research, besides addressing the important question of the role of latent elements in organization design and demonstrating this can be done using system dynamics modeling and computer simulation, should also be of value to the design and management of higher education institutions.
99

Experimental and computer aided investigation of cutting process of brittle materials : магистерская диссертация / Экспериментальное и компьютерное исследование процессов резания хрупких материалов

Kharitonov, P. V., Харитонов, П. В. January 2016 (has links)
This master thesis work was aimed to enhance the computer aided modeling of cutting processes for hard brittle materials in optical and microelectronic industry. The parametric computer model of scribing the brittle wafer by diamond tool was developed using ANSYS APDL language and quasi-static conditions of treatment. Scribing of glass plates was realized by conic diamond tool on Roland CNC machine with different cutting parameters. Some experiments were made with coated glass plates. The surface quality of scribed plates was analyzed using AXIO ZEISS confocal microscope. The developed computer model enables predicting the defects zones in scribed brittle plate and searching the optimal cutting parameters and tool geometry. / Данная магистерская диссертация направлена на внедрение компьютерного моделирования технологических процессов резания применитльно к твердым хрупким материалам в оптической и электронной индустрии. Создана параметрическая компьютерная модель процесса скрайбирования алмазным инструментом для хрупкой пластины с использованием языка программирования ANSYS APDL в рамках квазистатического приближения. Скрайбирование стеклянныхз пластин было произведено коническим инструментом на станке с ЧПУ марки Roland с различными параметрами режима резания. Часть экспериментов проведена на пластинах с покрытием. Качество поверхности после скрайбирования было исследовано с помощью конфокального микроскопа AXIO ZEISS. Построенная компьютерная модель позволяет прогнозировать зону дефектности в скрайбированных хрупких пластинах и оптимизировать параметры режима резания, а также геометрию режущего инструмента.
100

Computer Modeling of Geology in the Sparta and Montpelier Quadrangles of Clay and Chickasaw Counties, Mississippi: A Tantalizing Near Miss

Defibaugh y Chávez, Jason 07 August 2004 (has links)
This project attempted to combine digital data sets to define and map geologic features in the Sparta and Montpelier quadrangles of Chickasaw and Clay counties in northeastern Mississippi. LANDSAT TM, digital elevation, and soil permeability data was used in conjunction with reference data for the Sparta quadrangle to build a computer model. Variables used in the model were: geology, slope, soil permeability, vegetation indices, the first three bands of a tasseled cap transformation, and drainage frequency. The data used was LANDSAT TM 30 meter imagery, digital elevation models, also at 30 meter resolution, Penn State STASGO soils data, and the existing map of the Sparta quadrangle. The purpose of this project was to use digital data to remotely map geologic features through heavy vegetation using a computer model. While the results of this project were not completely successful, the methods used show some potential for future application.

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