The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Luciano Cunha De Araujo Pimenta - One of the best experts on this subject based on the ideXlab platform.
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Navegação de robôs móveis baseada na equação de laplace: uma nova abordagem utilizando elementos finitos
Universidade Federal de Minas Gerais, 2005Co-Authors: Luciano Cunha De Araujo PimentaAbstract:Este trabalho aborda o problema de navegação de robôs móveis. Mais especificamente, é proposta uma nova abordagem, no contexto de robótica, para a solução da equação Laplace visando a construção de funções de navegação. Esta nova abordagem consiste na aplicação do Método de Elementos Finitos, o que permite o tratamento de obstáculos e robôs de formatos complexos. O trabalho ainda propõe regras para a definição de condições de contorno para a solução da equação de Laplace, as quais tornam a metodologia proposta completa, isto é, caso exista um caminho possível, o robô sempre atinge o alvo num tempo finito, independentemente da posição e orientação iniciais. Uma nova condição de contorno, dentro do contexto de robótica, chamada Condição de Contorno Periódica, também é proposta neste trabalho, permitindo um tratamento fechado da orientação do robô. O tratamento da orientação do robô passa também pela construção de espaços de configurações em R3, utilizados quando a orientação de robôs navegando no plano é considerada. Esta dissertação propõe um novo algoritmo para uma construção aproximada desses espaços. Os resultados do trabalho são validados numa plataforma constituída de robôs holonômicos reaisThis work addresses the mobile robot navigation problem. More specifically, we propose a novel approach, in the robotics context, for constructing navigation functions based on the Laplaces Equation solution. This approach is based on Finite Elements Methods, which allows for complex shaped obstacles and robots. Also, we propose rules for attaching boundary conditions to the boundary domain, in order to solve the Laplaces Equation, thus guaranteeing completeness for the proposed methodology, i.e., if a path exists the robot always reach the goal in a finite time, independently of its initial position and orientation. A new boundary condition, called Periodic Condition, is proposed and used to take into account the robots orientation. Additionally, we propose an algorithm for constructing configurations spaces in R3, useful when three degrees of freedom, planar robots are considered. Our methodology is validated in actual, holonomic mobile robot
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Navegação de robôs móveis baseada na equação de laplace: uma nova abordagem utilizando elementos finitos
'Revista da Faculdade de Direito da UFMG', 2005Co-Authors: Luciano Cunha De Araujo PimentaAbstract:Exportado OPUSMade available in DSpace on 2019-08-12T17:47:00Z (GMT). No. of bitstreams: 1 468m.pdf: 3181706 bytes, checksum: 13c13dec8dc291293e3d60db4bef29b6 (MD5) Previous issue date: 17Este trabalho aborda o problema de navegação de robôs móveis. Maisespecificamente, é proposta uma nova abordagem, no contexto de robótica, para a solução da equação Laplace visando a construção de funções de navegação. Esta nova abordagem consiste na aplicação do Método de Elementos Finitos, o que permite o tratamento de obstáculos e robôs de formatos complexos. O trabalho ainda propõe regras para a definição de condições de contorno para a solução da equação de Laplace, as quais tornam a metodologia proposta completa, isto é, caso exista um caminho possível, o robô sempre atinge o alvo num tempo finito, independentemente da posição e orientação iniciais. Uma nova condição de contorno, dentro do contexto de robótica, chamada Condição de Contorno Periódica, também é proposta neste trabalho, permitindo um tratamento fechado da orientação do robô. O tratamento da orientação do robô passa também pela construção de espaços de configurações em R3, utilizados quando a orientação de robôs navegando no plano é considerada. Esta dissertação propõe um novo algoritmo para uma construção aproximada desses espaços. Os resultados do trabalho são validados numa plataforma constituída de robôs holonômicos reaisThis work addresses the mobile robot navigation problem. More specifically, we propose a novel approach, in the robotics context, for constructing navigation functions based on the Laplaces Equation solution. This approach is based on Finite Elements Methods, which allows for complex shaped obstacles and robots. Also, we propose rules for attaching boundary conditions to the boundary domain, in order to solve the Laplaces Equation, thus guaranteeing completeness for the proposed methodology, i.e., if a path exists the robot always reach the goal in a finite time, independently of its initial position and orientation. A new boundary condition, called Periodic Condition, is proposed and used to take into account the robots orientation. Additionally, we propose an algorithm for constructing configurations spaces in R3, useful when three degrees of freedom, planar robots are considered. Our methodology is validated in actual, holonomic mobile robot
Schmidt Fabrice - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulation of resin transfer molding using BEM and level set method
UNIVERSITY OF BRESCIA, 2010Co-Authors: Gantois Renaud, Cantarel Arthur, Dusserre Gilles, Felices Jean-noël, Schmidt FabriceAbstract:International audienceResin Transfer Molding is widely used to produce fiber-reinforced materials. In the process, the resin enters a close mold containing the dry fiber preform. For mold designer, numerical simulation is a useful tool to optimize the mold filling, in particular to identify the best positions of the ports and the vents. An issue in mold filling simulation is the front tracking, because the shape of the resin front changes during the flow. In particular, topological changes can appear resulting from internal obstacles dividing the front or multi-injection. A previous approach [1] using the Boundary Element Method (BEM) in a moving mesh framework shows the capability of the method to compute accuratlely the front propagation at low CPU time. The present paper describes a method developed to handle complex shapes, using BEM together with a Level Set approach. Numerical results in two dimensions are presented, assuming a Newtonian non-reactive fluid, and an homogeneous and not-deformable reinforcement. The resin flow in the fibrous reinforcement is modeled using Darcy's law and mass conservation. The resulting Equation reduces to Laplace's Equation considering an isotropic equivalent mold. Laplaces Equation is solved at each time step using a constant Boundary Element Method to compute the normal velocity at the flow front. It is extended to the fixed grid and next used to feed a Level Set solver computing the signed distance to the front. Our model includes a boundary element mesher and a Narrow Band method to speed up CPU time. The numerical model is compared with an analytical solution, a FEM/VOF-based simulation and experimental measurements for more realistic cases involving multiple injection ports and internal obstacles
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Numerical simulation of resin transfer molding using BEM and level set method
'Springer Science and Business Media LLC', 2010Co-Authors: Gantois R., Cantarel Arthur, Dusserre Gilles, Felices Jean-noël, Schmidt FabriceAbstract:Issu de : ESAFORM 2010 - 13th International ESAFORM conference on material forming, Brescia, ITALY, April 7-9, 2010International audienceResin Transfer Molding is widely used to produce fiber-reinforced materials. In the process, the resin enters a close mold containing the dry fiber preform. For mold designer, numerical simulation is a useful tool to optimize the mold filling, in particular to identify the best positions of the ports and the vents. An issue in mold filling simulation is the front tracking, because the shape of the resin front changes during the flow. In particular, topological changes can appear resulting from internal obstacles dividing the front or multi-injection. A previous approach [1] using the Boundary Element Method (BEM) in a moving mesh framework shows the capability of the method to compute accuratlely the front propagation at low CPU time. The present paper describes a method developed to handle complex shapes, using BEM together with a Level Set approach. Numerical results in two dimensions are presented, assuming a Newtonian non-reactive fluid, and an homogeneous and not-deformable reinforcement. The resin flow in the fibrous reinforcement is modeled using Darcy's law and mass conservation. The resulting Equation reduces to Laplace's Equation considering an isotropic equivalent mold. Laplaces Equation is solved at each time step using a constant Boundary Element Method to compute the normal velocity at the flow front. It is extended to the fixed grid and next used to feed a Level Set solver computing the signed distance to the front. Our model includes a boundary element mesher and a Narrow Band method to speed up CPU time. The numerical model is compared with an analytical solution, a FEM/VOF-based simulation and experimental measurements for more realistic cases involving multiple injection ports and internal obstacles
Mayfield, Caleb James - One of the best experts on this subject based on the ideXlab platform.
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Harmonic functions and the Dirichlet problem
University of Missouri--Columbia, 2017Co-Authors: Mayfield, Caleb JamesAbstract:[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Let [omega] be an open and connected subset of the complex plane. A real valued function u : [omega] [right arrow] R is said to be harmonic if it has continuous first and second partial derivatives and satisfies Laplaces Equation [delta]u = [derivative]2u / [derivative]x2 + [derivative]2u / [derivative]y2 = 0. We begin by investigating basic properties of harmonic functions and defining the harmonic conjugate gradient and harmonic conjugate functions. From this we prove the mean value property and maximum and minimum modulus principle for harmonic functions. Suppose we have a two dimensional plate of homogeneous material whose boundaries are heated to a constant temperature. We investigate solving the Dirichlet problem, which involves Laplaces Equation and specific boundary values. Along with examples, we show that we can solve the Dirichlet problem on a disk using the Poisson integral along with Fourier series. We generalize the Dirichlet problem to any region by investigating conformal mappings. We find a solution to the Dirichlet problem on a general region in the plane by transforming it to a problem in the upper half plane and using the Poisson integral
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Harmonic functions and the Dirichlet problem
University of Missouri--Columbia, 2017Co-Authors: Mayfield, Caleb JamesAbstract:[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Let [omega] be an open and connected subset of the complex plane. A real valued function u : [omega] [right arrow] R is said to be harmonic if it has continuous first and second partial derivatives and satisfies Laplaces Equation [delta]u = [derivative]2u / [derivative]x2 + [derivative]2u / [derivative]y2 = 0. We begin by investigating basic properties of harmonic functions and defining the harmonic conjugate gradient and harmonic conjugate functions. From this we prove the mean value property and maximum and minimum modulus principle for harmonic functions. Suppose we have a two dimensional plate of homogeneous material whose boundaries are heated to a constant temperature. We investigate solving the Dirichlet problem, which involves Laplaces Equation and specific boundary values. Along with examples, we show that we can solve the Dirichlet problem on a disk using the Poisson integral along with Fourier series. We generalize the Dirichlet problem to any region by investigating conformal mappings. We find a solution to the Dirichlet problem on a general region in the plane by transforming it to a problem in the upper half plane and using the Poisson integral.Dr. Loukas Grafakos, Thesis Supervisor.Includes bibliographical references (pages 64)
Sardar Muhammad Hussain - One of the best experts on this subject based on the ideXlab platform.
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Simulação do escoamento de água subterrânea pelo método de elemento analítico
'American Psychological Association (APA)', 2017Co-Authors: Sardar Muhammad HussainAbstract:Groundwater studies face computational limitations when providing local detail within regional models. The researchers are concentrated on applying the numerical models to minimize the difference between the physical reality and the implemented numerical model by considering the minimum computational cost. This work consists of the study of line-elements (such as line-doublets, circles, polygons, fractures) using the Analytic Element Method (AEM) for groundwater flow. In this work, we consider the study of two-dimensional groundwater flow in fractured porous media by the Analytic Element Method. We develop a numerical solution based on a series expansion for a problem with more than one fracture. Each fracture has an influence that can be expanded in a series that satisfies Laplaces Equation exactly. In the series expansion, the unknown coefficients are obtained from the discharge potentials of all other elements that are related to the expansion coefficients. Sizes, locations and conductivities for all inhomogeneities are selected arbitrarily. This work also discusses a matrix method obtained by imposing the intern boundary conditions for the Analytic Element Method. The convergence analysis of a Gauss-Seidel type iterative method is also discussed.Estudos de águas subterrâneas enfrentam limitações computacionais ao fornecer detalhes locais em modelos regionais. Os pesquisadores estão concentrados na aplicação dos modelos numéricos para minimizar a diferença entre a realidade física e o modelo numérico implementado considerando o custo computacional mínimo. Este trabalho consiste no estudo de elementos de linha (como line-doublets, círculos, polígonos, fraturas) usando o Método de Elemento Analítico (AEM) para o fluxo de águas subterrâneas. Neste trabalho, consideramos o estudo do fluxo bidimensional de águas subterrâneas em meios porosos fraturados pelo Método dos Elementos Analíticos. Desenvolvemos uma solução numérica baseada em uma expansão em série para um problema com mais de uma fratura. Cada fratura tem uma influência que pode ser expandida em uma série que satisfaça exatamente a equação de Laplace. Na expansão da série, os coeficientes desconhecidos são obtidos a partir dos potenciais de descarga de todos os outros elementos que estão relacionados aos coeficientes de expansão. Tamanhos, locais e condutividades para todas as não-homogeneidades são arbitrariamente selecionados. Este trabalho também discute o método da matriz obtido impondo as condições de contorno do interno para o Método do Elemento Analítico. A análise de convergência de um método iterativo tipo Gauss-Seidel também é discutida
Dusserre Gilles - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulation of resin transfer molding using BEM and level set method
UNIVERSITY OF BRESCIA, 2010Co-Authors: Gantois Renaud, Cantarel Arthur, Dusserre Gilles, Felices Jean-noël, Schmidt FabriceAbstract:International audienceResin Transfer Molding is widely used to produce fiber-reinforced materials. In the process, the resin enters a close mold containing the dry fiber preform. For mold designer, numerical simulation is a useful tool to optimize the mold filling, in particular to identify the best positions of the ports and the vents. An issue in mold filling simulation is the front tracking, because the shape of the resin front changes during the flow. In particular, topological changes can appear resulting from internal obstacles dividing the front or multi-injection. A previous approach [1] using the Boundary Element Method (BEM) in a moving mesh framework shows the capability of the method to compute accuratlely the front propagation at low CPU time. The present paper describes a method developed to handle complex shapes, using BEM together with a Level Set approach. Numerical results in two dimensions are presented, assuming a Newtonian non-reactive fluid, and an homogeneous and not-deformable reinforcement. The resin flow in the fibrous reinforcement is modeled using Darcy's law and mass conservation. The resulting Equation reduces to Laplace's Equation considering an isotropic equivalent mold. Laplaces Equation is solved at each time step using a constant Boundary Element Method to compute the normal velocity at the flow front. It is extended to the fixed grid and next used to feed a Level Set solver computing the signed distance to the front. Our model includes a boundary element mesher and a Narrow Band method to speed up CPU time. The numerical model is compared with an analytical solution, a FEM/VOF-based simulation and experimental measurements for more realistic cases involving multiple injection ports and internal obstacles
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Numerical simulation of resin transfer molding using BEM and level set method
'Springer Science and Business Media LLC', 2010Co-Authors: Gantois R., Cantarel Arthur, Dusserre Gilles, Felices Jean-noël, Schmidt FabriceAbstract:Issu de : ESAFORM 2010 - 13th International ESAFORM conference on material forming, Brescia, ITALY, April 7-9, 2010International audienceResin Transfer Molding is widely used to produce fiber-reinforced materials. In the process, the resin enters a close mold containing the dry fiber preform. For mold designer, numerical simulation is a useful tool to optimize the mold filling, in particular to identify the best positions of the ports and the vents. An issue in mold filling simulation is the front tracking, because the shape of the resin front changes during the flow. In particular, topological changes can appear resulting from internal obstacles dividing the front or multi-injection. A previous approach [1] using the Boundary Element Method (BEM) in a moving mesh framework shows the capability of the method to compute accuratlely the front propagation at low CPU time. The present paper describes a method developed to handle complex shapes, using BEM together with a Level Set approach. Numerical results in two dimensions are presented, assuming a Newtonian non-reactive fluid, and an homogeneous and not-deformable reinforcement. The resin flow in the fibrous reinforcement is modeled using Darcy's law and mass conservation. The resulting Equation reduces to Laplace's Equation considering an isotropic equivalent mold. Laplaces Equation is solved at each time step using a constant Boundary Element Method to compute the normal velocity at the flow front. It is extended to the fixed grid and next used to feed a Level Set solver computing the signed distance to the front. Our model includes a boundary element mesher and a Narrow Band method to speed up CPU time. The numerical model is compared with an analytical solution, a FEM/VOF-based simulation and experimental measurements for more realistic cases involving multiple injection ports and internal obstacles
