247 resultados para transformada de Laplace
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The second-order differential equations that describe the polyphase transmission line are difficult to solve due to the mutual coupling among them and the fact that the parameters are distributed along their length. A method for the analysis of polyphase systems is the technique that decouples their phases. Thus, a system that has n phases coupled can be represented by n decoupled single-phase systems which are mathematically identical to the original system. Once obtained the n-phase circuit, it's possible to calculate the voltages and currents at any point on the line using computational methods. The Universal Line Model (ULM) transforms the differential equations in the time domain to algebraic equations in the frequency domain, solve them and obtain the solution in the frequency domain using the inverse Laplace transform. This work will analyze the method of modal decomposition in a three-phase transmission line for the evaluation of voltages and currents of the line during the energizing process.
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We discuss the one-sided Green's function, associated with an initial value problem and the two-sided Green's function related to a boundary value problem. We present a specific calculation associated with a differential equation with constant coefficients. For both problems, we also present the Laplace integral transform as another methodology to calculate these Green's functions and conclude which is the most convenient one. An incursion in the so-called fractional Green's function is also presented. As an example, we discuss the isotropic harmonic oscillator.
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Pós-graduação em Engenharia Mecânica - FEG
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Pós-graduação em Ciência dos Materiais - FEIS
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Pós-graduação em Química - IQ
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Pós-graduação em Engenharia Mecânica - FEG
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Pós-graduação em Genética e Melhoramento Animal - FCAV
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A disponibilidade de nutrientes é um dos fatores que controla a produção primária dos ecossistemas. O objetivo deste trabalho foi avaliar o efeito da concentração de nitrato (N-NO3) no crescimento da macrófita aquática flutuante Pistia stratiotes. Um experimento com delineamento totalmente casualisado foi realizado em laboratório, consistindo de três réplicas e cinco tratamentos: (1) sem adição de nitrato; (2)196μg.L-1, (3) 490μg.L-1, (4) 980μg.L-1 e (5) 1960μg.L-1. Em intervalos de sete dias, durante 70 dias, foi obtida a massa fresca de P. stratiotes. A massa fresca foi transformada em massa seca, e a esses valores aplicou-se o modelo de crescimento logístico. Também foram analisados o diâmetro de roseta, o número de indivíduos, o volume de raiz, a absorção de N-NO3 e P-PO4 por P. stratiotes e os teores de nitrogênio, fósforo e clorofila a e b da biomassa. Os valores médios de capacidade suporte (K) encontrados foram: (1) 220,9 gMS.m-2; (2) 262,8 gMS.m-2; (3) 288,3 gMS.m-2; (4) 356,9 gMS.m-2; e (5) 394,6 gMS.m-2. Os resultados indicam que a relação entre concentração de nitrato e K é uma hipérbole que apresenta K como valor assintótico. Conclui-se que o aumento da disponibilidade de nitrato promove o aumento no crescimento desta espécie. Conclui-se também que P. stratiotes apresenta consumo de luxúria de nitrogênio e que a maior disponibilidade de nitrogênio promove o aumento do número de indivíduos e do diâmetro da roseta e a diminuição da relação volume de raiz/biomassa do indivíduo.
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A Educação Física escolar parece passar por um momento de crise de valores, a escola está ensinando e o aluno efetivamente aprendendo? O ensino tem se convertido em aprendizagem significativa dos alunos? Parece que há falta de diálogo entre professores e alunos, o que acaba gerando desinteresse por parte dos alunos na sala de aula, muitas vezes refletida, em situações de indisciplina. a imagem do professor perante os alunos de anos atrás mostra-se transformada quando comparada com a imagem dos dias de hoje. Esse já não é mais o retentor do saber, autoritário e até mesmo temido ou seja sua imagem não parece muito bem definida para os alunos. As aulas não são tão interessantes para esses novos alunos que sofrem grande influência das novas tecnologias, com grandes quantidades de informação e tem necessidades que parecem não serem mais supridas, principalmente quando o professor não transforma sua metodologia de acordo com essas novas exigências. Portanto o objetivo desse estudo foi investigar a leitura que os professores experientes estão fazendo dos novos alunos, se perceberam diferenças entre os alunos ao longo do tempo e como estão adaptando suas metodologias para ensinar. A pesquisa foi qualitativa descritiva, que utilizou como método de coleta de dados uma entrevista semi-estruturada com professores que apresentam no mínimo cinco anos de docência e que sejam atuantes da área da Educação Física. Os principais resultados alcançados foi a percepção por parte dos professores de alunos com famílias desestruturadas, a influência das tecnologias, a indisciplina na escola, a falta de interesse nas aulas, agressão verbal e professores cansados com dificuldades de adaptar sua aula à realidade escolar, gerando um quadro que precisa ser mudado para que a cultura corporal consiga ser transmitida da melhor maneira.
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Cardoso Island, settled in the south of paulista region, is characterized by its ecological importance due to the great biodiversity of Mata Atlântica and for accommodating several kinds of ecosystems as mangroves, which were considered by UNESCO as human natural ownership. The mangroves are among the most important marine ecosystems, known as warranty of biological productivity and diversity and supply of food and economical resources to the local population. Although the island has been transformed in a state park for preservation, it hasn’t become free from environmental impacts made by antropical activities. This way it was proposed a rebuilt of an evolutionary process in the region, having as an objective to subsidize programs of environmental conservation and planning , aiming to a sustainable development. For this it was used a isobasis methodological analyses where by the drainage channels and its confluences makes relative maps to the different base levels represented by the isobasis, characterizing itself by an attempt to rebuilt the preterit local landscape. There were elaborated eight maps referring to four orders of confluences met in the region of Cardoso Island and round it where you can conclude it is about an appropriate methodology to rebuilt preterits environments that specially aim to actions of environmental planning and conservation.
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In this study, the drug indomethacin, a non-steroidal anti-inflammatory indoleacetic acid derivative and the complex of indomethacin and lanthanum (III) in solid form were synthesized and characterized by Thermogravimetry (TGA), Differential Thermal Analysis (DTA), Differential Scanning Calorimetry (DSC) and powder X-ray diffractometry (XRD), infrared vibrational spectroscopy by diffuse reflectance (FTIR) and complexometric titration with EDTA. With the TG curves it was possible to determine the stoichiometry of the complex as La(Ind)3·3.5H2O where Ind is the drug indomethacin. The result of thermal analyzes provided information on the thermal stability, enthalpy of dehydration and thermal behavior of the compounds. The infrared spectrum and with the aid of theoretical calculations suggests that the indomethacin is coordinated by the carboxylate group in the bidentate mode
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Through the data acquisition system of the instrument Brazilian Solar Spectroscope (BSS) at INPE, solar observations in the decimetric radio wave band (1000-2500 MHz) are regularly made. This data is showed as dynamic spectra using the software BSSView created for this purpose. The process of data acquisition can be influenced by various sources, dificulting the resulting dynamic spectrum analysis. The objective of this work is to create a computational routine that eliminates dynamic components of the spectrum attributed to interfering signals and integrate it into BSSView. It was done a preliminary study on the programming language Interactive Data Language (IDL), in which the BSSView was developed, and the Fourier transform, that is required for the application of the filter
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In this work, air dielectric barrier discharge (DBD) operating at two different frequencies (60 Hz and 17 kHz) was used to improve surface properties of polypropylene (PP). The changes in surface hydrophilicity were investigated by contact angle measurements. The modifications in chemical composition of PP surface were studied by X-ray photoelectron spectroscopy (XPS) and Fourier-transformed infrared spectroscopy (FTIR). The PP roughness were analyzed before and after the DBD treatment using atomic force microscopy (AFM). In order to compare the results obtained at different frequencies, the analyses are presented as a function of the deposited energy density. The results show that both DBD treatments led to formation of low-molecular weight oxidized material (LMWOM). It tends to agglomerate into small mounts on the surface, as shown by AFM analyses. These structures are weakly bounded to the surface and can be easily removed by rinsing in polar solvents. After washing the DBD-treated samples, the PP partially recovers its original wetting characteristics. This suggests that oxidation also occurred at deeper and more permanent levels on the PP samples. Comparing both DBD treatments, the 17 kHz process was found to be more efficient in introducing oxygen groups to the PP surface