Proposal of an alternative transmission line model for symmetrical and asymmetrical configurations

This article shows a transmission line model for simulation of fast and slow transients, applied to symmetrical or asymmetrical configurations. A transmission line model is developed based on lumped elements representation and state-space techniques. The proposed methodology represents a practical procedure to model three-phase transmission lines directly in time domain, without the explicit or implicit use of inverse transforms. In three-phase representation, analysis modal techniques are applied to decouple the phases in their respective propagation modes, using a correction procedure to set a real and constant matrix for untransposed lines with or without vertical symmetry plane. The proposed methodology takes into account the frequency-dependent parameters of the line and in order to include this effect in the state matrices, a fitting procedure is applied. To verify the accuracy of the proposed state-space model in frequency domain, a simple methodology is described based on line distributed parameters and transfer function associated with input/output signals of the lumped parameters representation. In addition, this article proposes the use of a fast and robust integration procedure to solve the state equations, enabling transient and steady-state simulations. The results obtained by the proposed methodology are compared with several established transmission line models in EMTP, taking into account an asymmetrical three-phase transmission line. The principal contribution of the proposed methodology is to handle a steady fundamental signal mixed with fast and slow transients, including impulsive and oscillatory behavior, by a practical procedure applied directly in time domain for symmetrical or asymmetrical representations. (C) 2011 Elsevier Ltd. All rights reserved.

Alternative Model of Three-Phase Transmission Line Theory-Based Modal Decomposition

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.

Corona Discharge Model for Transmission Lines by Lumped Elements

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.

Proposal of a Transmission Line Model Based on Lumped Elements: An Analytic Solution

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alternative proposal for Modal Representation of a Non-transposed Three-Phase Transmission Line with a Vertical Symmetry Plane

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.

Dysautonomia and ventricular dysfunction in the indeterminate form of Chagas disease

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.

Predictors of Right Ventricle Dysfunction After Anterior Myocardial Infarction

Background: Regardless significant therapeutic advances, mortality and morbidity after myocardial infarction (MI) are still high. For a long time, the importance of right ventricle (RV) function has been neglected. Recently, RV dysfunction has also been associated with poor outcomes in the setting of heart failure. The shape, location, and contraction conditions make the RV chamber assessment technically challenging.Methods: Our study identified clinical characteristics and left ventricle (LV) echocardiographic data performed 3-5 days after MI that could be associated with RV dysfunction (RV fractional area change [FAC] < 35%) 6 months after MI.Results: The RV dysfunction group consisted of 11 patients (RV FAC 29.4% +/- 5.2) and the no RV dysfunction group of 71 patients (RV FAC 43.7% +/- 5.1); (P < 0.001). Both groups presented the same baseline clinical characteristics. Left atrium (LA), interventricular septum (IVS), and left ventricular posterior wall (LVPW) were larger in RV dysfunction than in no RV dysfunction. Conversely, E wave deceleration time (EDT) was lower in RV dysfunction when compared with no RV dysfunction. Left atrium(adj) (adjusted by gender, age, infarct size, and body mass index) (odds ratio [OR], 1.22; confidence interval [CI], 1.016-1.47; P = 0.032), interventricular septum(adj) (OR, 1.49; CI, 1.01-2.23; P = 0.044), and E wave deceleration time(adj) (OR, 0.98; CI, 0.97-0.98; P = 0.029) assessed soon after MI predicted RV failure after 6-months.Conclusions: LV diastolic dysfunction, resulting from anterior MI and assessed 3-5 days after the event, may play an important role in predicting RV dysfunction 6 months later.

A marker-and-cell approach to free surface 2-D multiphase flows

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phosphorus magnetic resonance spectroscopy in malformations of cortical development

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Electromyographic activity of shoulder muscles during exercises performed with oscillatory and non-oscillatory poles

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.

Padrão de co-ativação dos músculos do tronco durante exercícios com haste oscilatória

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.

Electromyographic activity of trunk muscles during exercises with flexible and non-flexible poles

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.

Search for heavy long-lived charged particles in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Light Front Boson Model Propagation

The scope and aim of this work is to describe the two-body interaction mediated by a particle (either the scalar or the gauge boson) within the light-front formulation. To do this, first of all we point out the importance of propagators and Green functions in Quantum Mechanics. Then we project the covariant quantum propagator onto the light front time to get the propagator for scalar particles in these coordinates. This operator propagates the wave function from x(+) = 0 to x(+) > 0. It corresponds to the definition of the time ordering operation in the light front time x(+). We calculate the light-front Green's function for 2 interacting bosons propagating forward in x(+). We also show how to write down the light front Green's function from the Feynman propagator and finally make a generalization to N bosons.

A generalized alternating-direction implicit scheme for incompressible magnetohydrodynamic viscous flows at low magnetic Reynolds number

This paper presents numerical simulations of incompressible fluid flows in the presence of a magnetic field at low magnetic Reynolds number. The equations governing the flow are the Navier-Stokes equations of fluid motion coupled with Maxwell's equations of electromagnetics. The study of fluid flows under the influence of a magnetic field and with no free electric charges or electric fields is known as magnetohydrodynamics. The magnetohydrodynamics approximation is considered for the formulation of the non-dimensional problem and for the characterization of similarity parameters. A finite-difference technique is used to discretize the equations. In particular, an extension of the generalized Peaceman and Rachford alternating-direction implicit (ADI) scheme for simulating two-dimensional fluid flows is presented. The discretized conservation equations are solved in stream function-vorticity formulation. We compare the ADI and generalized ADI schemes, and show that the latter is more efficient in simulating low Reynolds number and magnetic Reynolds number problems. Numerical results demonstrating the applicability of this technique are also presented. The simulation of incompressible magneto hydrodynamic fluid flows is illustrated by numerical solution for two-dimensional cases. (c) 2007 Elsevier B.V. All rights reserved.