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Navegando por Assunto "FDTD method"

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    Análise da eficiência de blindagem de estruturas indoors construídas com lâminas "finas" condutoras elétricas, através do método FDTD
    (Universidade Federal do Pará, 2009-09-25) ROCHA, Rita de Cássia Florêncio; SOUZA SOBRINHO, Carlos Leônidas da Silva; http://lattes.cnpq.br/1450994881555781
    This work presents results regarding electromagnetic shielding structures using thin conductive sheets. The simulations were performed by using the finite difference time domain method (FDTD), in which a sub-cellular formulation has been implemented for modeling thin steel walls. The implementation was validated via comparison of the obtained results to those available in the literature. Then, several geometries were tested, including apertures on the structures and by changing the space between double shielding walls. Finally, a complete high-voltage laboratory was simulated (by analyzing the shielding efficiency) considering a closed structure and apertures.
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    Antenas de grafeno com controle de diagrama de radiação: projeto e modelagem via método FDTD
    (Universidade Federal do Pará, 2015-08-28) RODRIGUES, Nilton Rodolfo Nascimento Melo; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/0684541646225359; OLIVEIRA, Rodrigo Melo e Silva de; http://lattes.cnpq.br/4768904697900863
    In this work, it is developed a mathematical formulation for modelling Graphene sheets in the three-dimensional lattice used to solve Maxwell’s equations with Yee’s algorithm. The technique is based on piecewise linear recursive convolution method and on thin material sheets technique, valid in intraband range. The HFSS software is used for to designing, for the first time, graphene antennas with dynamic control of the radiation pattern main lobe by tuning the chemical potential of graphene sheets used as passive elements. The numerical method developed in this work fully agrees with the results obtained by using HFSS (this one is based on the Finite Element Method).
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    Estudo experimental de transitórios eletromagnéticos em sistemas de aterramento elétrico devidos a pulsos de descargas atmosféricas
    (Universidade Federal do Pará, 2015-05-29) CARVALHO, Lorena de Fátima Pinheiro de; OLIVEIRA, Rodrigo Melo e Silva de; http://lattes.cnpq.br/1450994881555781
    In this dissertation, we present a study on the transient and steady-state behaviors of grounding systems when subjected to surges with the waveform of a lightning discharge. The analyses of grounding systems were made using data obtained through experiments conducted in the field and numerical simulations based on the finite-difference method applied to solve Maxwell’s equations in the time domain. In numerical simulations, the experimental setup (rods, cables, resistor and injected signal) and the electromagnetic parameters (conductivity, permittivity and magnetic permeability) of soil and vacuum were modeled numerically. There was good agreement between the measured signals during the experimental tests and their respective signals obtained numerically. This agreement between measured and simulated transient signals was obtained by taking certain technical precautions when designing the experimental setup. Such technical precautions, which are usually not explicitly mentioned in technical literature, are properly addressed and discussed in this dissertation.
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    Modelagem através do método das diferenças finitas no domínio do tempo (FDTP) de solos dispersivos utilizando aproximações de Padé validada com experimentos em campo
    (Universidade Federal do Pará, 2015-08-31) FUJIYOSHI, Daiyuki Maia; OLIVEIRA, Rodrigo Melo e Silva de; http://lattes.cnpq.br/4768904697900863
    The Amazonian soil of Belém is modeled as a dispersive material, of which the electrical conductivity is dependent on the frequency. For this aim, we use the Padé's approxima-tion in frequency domain, which is applied to Ampère's law. Special update equations for electric field in time domain are obtained by applying time averaging and the in-verse Fourier transform. The results obtained by numerical simulations performed with the FDTD method are compared to transient responses measured in field. Lightning-patterned pulses are injected in classical grounding systems. Excellent agreement is ob-served, which validates the developed numerical method.
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    Simulação, em ambiente computacional, do método de Wenner e obtenção da resistência de um sistema de aterramento usando FDTD
    (Universidade Federal do Pará, 2007-09-21) SOUZA JÚNIOR, Emanuel dos Santos; SOUZA SOBRINHO, Carlos Leônidas da Silva; http://lattes.cnpq.br/1450994881555781
    This work presents a new computational methodology, for the attesting practices of soil bedding by the method of Wenner and the calculation of earth resistance by method Volt-ammeter. This methodology allows the grounding planner system evaluate his acting accurately and propose solutions that assist the requirements of economy and safety. The calculation base that relates the electric and magnetic fields is the differential equations of Maxwell, which, although concise and very elegant, are from difficult resolution in real problems of engineering. That is due to the fact that, in the real cases, the resolution is in a continuous domain and of complex geometry. The method FDTD transforms these differential equations, at continuous domain, in algebraic equations through the domain division in study. This transformation in algebraic equations in the whole divided domain takes to a principal system of great dimensions (dozens to hundreds of thousands of lines and columns), which, once resolved, it leads to the intended results that are written in a system of general coordinates and resolved numerically. In the method FDTD are used numeric field map techniques for determination of electric and magnetic fields, which allows the knowledge of current diffusion along the studied region. The region of grounding influence (analysis domain) is divided in small cells in the form of hexahedrons, making possible the calculation of the fields in their faces. A powder-processing work allows mapping the fields and currents distribution for the whole domain. As result, are obtained tension, current and grounding resistance values in the whole analysis domain. The code computacional used to model the resistance problem of a grounding and simulation of the method of Wenner, was developed in FORTRAN and implemented to be executed using parallel computation in cluster type Beowulf 10 knots, where the results were compared with analytical methods that already exist in the literature and are presented in the chapter VI.
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