937 resultados para Time-domain simulations
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In this paper is shown the development of a transmission line, based on discrete circuit elements that provide responses directly in the time domain and phase. This model is valid for ideally transposed rows represent the phases of each of the small line segments are separated in their modes of propagation and the voltage and current are calculated at the modal field. However, the conversion phase-mode-phase is inserted in the state equations which describe the currents and voltages along the line of which there is no need to know the user of the model representation of the theory in the field lines modal.
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This paper shows the insertion of corona effect in a transmission line model based on lumped elements. The development is performed considering a frequency-dependent line representation by cascade of pi sections and state equations. Hence, the detailed profile of currents and voltages along the line, described from a non-homogeneous system of differential equations, can be obtained directly in time domain applying numerical or analytic solution integration methods. The corona discharge model is also based on lumped elements and is implemented from the well-know Skilling-Umoto Model.
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The objective of this paper is to show an alternative representation in time domain of a non-transposed three-phase transmission line decomposed in its exact modes by using two transformation matrices. The first matrix is Clarke's matrix that is real, frequency independent, easily represented in computational transient programs (EMTP) and separates the line into quasi-modes a, b and zero. After that, Quasi-modes a and zero are decomposed into their exact modes by using a modal transformation matrix whose elements can be synthesized in time domain through standard curve-fitting techniques. The main advantage of this alternative representation is to reduce the processing time because a frequency dependent modal transformation matrix of a three-phase line has nine elements to be represented in time domain while a modal transformation matrix of a two-phase line has only four elements. This paper shows modal decomposition process and eigenvectors of a non-transposed three-phase line with a vertical symmetry plane whose nominal voltage is 440 kV and line length is 500 km.
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Background: the associations between autonomic function and biventricular function in patients with the indeterminate form of Chagas disease remains to be elucidated.Methods: In 42 asymptornatic patients and 19 healthy volunteers, the autonomic function was assessed by time domain indices of heart rate variability (HRV), analyzed for 24 h; the right ventricular function was assessed by fraction area change, right ventricle shortening, and systolic excursion of the tricuspid valve; and the left ventricular function was assessed by ejection fraction and transmittal flow velocities. Data were expressed as mean SD or medians (including the lower quartile and upper quartile). Groups were compared by Student's t or Mann-Whitney U test. Autonomic and ventricular function were correlated by Pearson's or Spearman's correlation coefficient. The level of significance was 5%.Results: Right and left ventricular systolic function indexes were comparable between groups. Transmittal flow velocities were decreased in the Chagas disease group (p < 0.05). The patients presented impaired HRV as indicated by the values of SDNN-day (80 (64-99) ms vs. 98 (78-127) ms; p = 0.045), SDNNI-24 It (54 (43-71) vs. 65 (54-105) ms; p = 0.027), SDNNI-day (49 (42-64) vs. 67 (48-76) ms; p = 0.045), pNN50-day (2.2 (0.7-5)% vs. 10 (3-11)%; p = 0.033); and pNN50-24 It (3 (1-7)% vs. 12 (8-19)%; p = 0.013). There were no correlations between the left ventricular diastolic indices and autonomic dysfunctional indices (p > 0.05).Conclusion: Patients with the indeterminate form of Chagas disease have both dysautonomia, and left ventricular diastolic dysfunction. However, the right ventricular function is preserved. Importantly, ventricular diastolic dysfunction and dysautonomia. are independent phenomena. (c) 2005 Elsevier B.V.. All rights reserved.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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CONTEXTUALIZAÇÃO: A dor e a disfunção no complexo articular do ombro é comumente encontrada na prática fisioterapêutica. Essas anormalidades musculoesqueléticas estão relacionadas à instabilidade e inadequado funcionamento cinemático, que dependem da integridade dos tecidos musculares. Assim, no sentido de prevenir e reabilitar esses sintomas, o uso da haste oscilatória vem sendo implantado para melhorar os resultados de técnicas cinesioterapêuticas. OBJETIVOS: Analisar a atividade eletromiográfica (EMG) dos músculos que estabilizam a articulação do ombro durante a realização de exercícios com haste oscilatória e haste não-oscilatória. MÉTODOS: Participaram do estudo 12 voluntárias com idade de 20,4±1,9 anos. Os dados EMG foram coletados nos músculos trapézio superior (TrS), trapézio inferior (TrI) e deltoide médio (DM) durante três diferentes exercícios realizados com haste oscilatória e haste não-oscilatória. O sinal EMG foi analisado no domínio do tempo pelo cálculo do Root Mean Square (RMS). Os valores de RMS foram normalizados pelo valor de pico obtido em todas as tentativas por cada músculo. A análise estatística foi feita com os testes ANOVA para medidas repetidas e post-hoc de Bonferroni. RESULTADOS: A atividade EMG dos músculos TrS, TrI e DM foi significativamente maior nos exercícios com haste oscilatória do que com haste não-oscilatória (todos p<0,001). Não foram significativas as diferenças na ativação desses músculos entre os exercícios. CONCLUSÃO: Os resultados do presente estudo indicaram que a haste oscilatória requisitou maior atividade EMG dos músculos do ombro e, assim, pode ser um instrumento útil no treinamento desses músculos.
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This study aimed to compare trunk muscle co-activation pattern during exercises using an oscillatory pole. Twelve volunteers participated in this study, in which they performed three different exercises. EMG activity of internal oblique (IO), external oblique (EO), rectus abdominis (RA), multifidus (MU) and iliocostalis lumborum (IL) was collected. The EMG signals were analyzed in time domain (RMS) and muscles activation ratios were computed as follow: anterior-posterior (A/P=RA+EO+IO/MU+IL), MU/IL and OE/OI. The bilateral oscillation of the pole in frontal plane (exercise II) promoted a higher value of MU/IL ratio than unilateral oscillation of the pole in sagital plane (exercise III). Also, the bilateral oscillation of the pole in frontal plane (exercise II) and the unilateral oscillation of the pole in sagital plane (exercise III) caused higher values of the IO/EO than bilateral oscillation of the pole in transversal plane (exercise I). Thus, the exercises II and III required higher activation of trunk stabilizer muscles, being more indicate for training, which aims higher recruitment of these muscles in daily activities.
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Objective: Hand-held flexible poles which are brought into oscillation to cause alternating forces on trunk, are advocated as training devices that are supposed to solicit increased levels of stabilizing trunk muscle activity. The aim of this study was to verify this claim by comparing electromyographic (EMG) activity of trunk muscles during exercises performed with a flexible pole and a rigid pole.Methods: Twelve healthy females performed three different exercises with flexible and rigid poles. EMG activity of iliocostalis lumborum (IL), multifidus (MU), rectus abdominis (RA), external oblique (EO) and internal oblique (IO), and was continuously measured. The EMG signals were analyzed in time domain by calculation of the Root Mean Square (RMS) amplitudes over 250 ms windows. The mean RMS-values over time were normalized by the maximum RMS obtained for each muscle.Results: The IO showed a 72% greater EMG activity during the exercises performed with the flexible pole than with the rigid pole (p = 0.035). In exercises performed in standing, the IO was significantly more active than when sitting (p = 0.006).Conclusion: As intended, the cyclic forces induced by the oscillating pole did increase trunk muscle activation. However, the effect was limited and significant for the IO muscle only.
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We discuss the role of dissipation in the explosive spinodal decomposition scenario of hadron production during the chiral transition after a high-energy heavy ion collision. We use a Langevin description inspired by microscopic nonequilibrium field theory results to perform real-time lattice simulations of the behavior of the chiral fields. We show that the effect of dissipation can be dramatic. Analytic results for the short-time dynamics are also presented. (c) 2005 Elsevier B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Avaliou-se o efeito da tranquilização e da anestesia sobre os índices da eletrocardiografia de alta resolução (ECGAR) em cães portadores de doença-de-chagas na fase crônica indeterminada. Foram utilizados oito cães, adultos, sem raça definida, fêmeas, submetidas a seis protocolos (grupos). No grupo 1, os animais estavam sem efeito de tranquilização ou anestesia; no grupo 2, foram tranquilizados com acepromazina; no 3, foram tranquilizados com a associação acepromazina e buprenorfina; no 4, estavam sob anestesia geral inalatória com isofluorano; no 5, sob anestesia geral inalatória com sevofluorano; e no 6, sob anestesia com propofol. Os animais foram submetidos a todos os protocolos, com um período de 15 dias entre cada avaliação. Não se verificou alteração significativa na duração do complexo QRS e do LAS40 entre os grupos, e o RMS40 permaneceu sem alteração significativa. O nível de ruído foi significativamente menor nos grupos 4, 5 e 6 em relação ao grupo 1. A anestesia facilitou o registro da ECGAR sem alterar os índices eletrocardiográficos .
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A simple and easily implemented method is developed to keep the vertical velocity equal to zero at the bottom and top of hydrostatic incompressible numerical models. The pressure is computed at the top by correcting its value given in the previous time step so that the vertical integral of the horizontal divergence is zero at each column. Numerical experiments that exhibit small time variations of pressure at the top are able to simplify the algorithm and save computer time. Numerical simulations illustrate the method effectiveness for a horizontal deformation-induced frontogenesis.
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This paper presents the fabrication and analysis of a three-dimensional FCC photonic crystal (PhC) based on a self-assembly synthesis of monodispersive latex spheres. Experimental optical characterization, achieved by measurements of the specular reflectance under variable angles, indicated the clear presence of a Bragg diffraction pattern. Results are further explored by theoretical calculations based on the Finite Difference Time Domain (FDTD) method to determine the full PhC band structure.