977 resultados para Sensore Hall Misura Corrente


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A estimulação transcraniana por corrente contínua (ETCC) é uma técnica não invasiva que apresenta características anti-fadigante e analgésica. Com o objetivo de testar seus efeitos sobre a diminuição da força e do aparecimento da dor muscular de início tardio (DMIT), apresentados após um evento de dano muscular induzido pelo exercício (DMIE), foi utilizado um estudo clínico de caráter experimental, controlado, randomizado e duplo-cego. A amostra foi composta por 24 jovens do sexo masculino, aparentemente saudáveis (19,7±1,8 anos; 23,6±3,65 IMC), os quais foram alocada, de forma aleatória e estratificada, nos seguintes grupos: G1: grupo controle; G2: grupo de estimulação após o dano e G3: grupo com estimulação antes e após o dano muscular. Os dados foram submetidos à estatística descritiva e análise de variância ANOVA, adotando-se um nível de significância de 5%. O aumento nos níveis séricos de CK (56.18%) e LDH (24,15%) comprovou a ocorrência do DMIE. Em contrapartida, após a análise de variância para comparação dos tratamentos aplicados, pode-se observar que não houve diferenças significativas nos níveis de CK (p= 0,3514) e força muscular (p= 0,9702). A DMIT transcorreu como esperado, mas sem diferença significativa entre os grupos (p= 0,4861). Estes dados demonstraram que a ETCC não foi capaz de modular a DMIT e a diminuição da força muscular após o DMIE em jovens aparentemente saudáveis

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Introduction: The sport practiced by people with disabilities has been growing in recent years. Consequently, advances in assessment and training methods have emerged. However, the paralympic sport keeps in tow these advances, with few specific studies that consider disability as intervening factor. The transcranial direct current stimulation (tDCS) is a technique that has proven to be capable of modulating brain function. Studies show beneficial effects of tDCS on muscle strength, power and fatigue during exercise. Objective: Investigate de the effect of tDCS on movement control in para-powerlifters. Methods: Eight subjects underwent two sessions of motion capture, which previously applied the anodic tDCS or sham sessions in the cerebellum. Three movements were performed with increasing load between 90-95% of 1MR. The movements were recorded by an 10 infrared cameras system which reconstructed the 3D trajectory of markers placed on the bar. Results: There have been changes between the anodic and sham conditions over bar level (initial, final, maximum during the eccentric and concentric phase) and in the difference between the final and initial bar level. Moreover, there was difference in bar level (final and during the eccentric phase) comparing athletes amputees and les autres. Conclusion: The findings of this study suggest that tDCS applied prior to the exercise over the cerebellum in para-powerlifters acts differently according to disability

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A presença de inibidores de germinação no fruto da beterraba pode comprometer o estande da cultura. O presente trabalho objetivou avaliar a interferência do período de imersão em água corrente no desempenho fisiológico das sementes de beterraba. Para tanto, sementes da cultivar Top Tall Early Wonder foram submetidas à ação de água corrente durante 0 (testemunha), 1; 1,5; 2; 3; 4; 5 e 6 horas, secadas e avaliadas pelo teste de germinação. A lavagem por duas horas foi suficiente para aumentar a germinação das sementes.

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The present work describes the use of a mathematical tool to solve problems arising from control theory, including the identification, analysis of the phase portrait and stability, as well as the temporal evolution of the plant s current induction motor. The system identification is an area of mathematical modeling that has as its objective the study of techniques which can determine a dynamic model in representing a real system. The tool used in the identification and analysis of nonlinear dynamical system is the Radial Basis Function (RBF). The process or plant that is used has a mathematical model unknown, but belongs to a particular class that contains an internal dynamics that can be modeled.Will be presented as contributions to the analysis of asymptotic stability of the RBF. The identification using radial basis function is demonstrated through computer simulations from a real data set obtained from the plant

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To obtain a process stability and a quality weld bead it is necessary an adequate parameters set: base current and time, pulse current and pulse time, because these influence the mode of metal transfer and the weld quality in the MIG-P, sometimes requiring special sources with synergistic modes with external control for this stability. This work aims to analyze and compare the effects of pulse parameters and droplet size in arc stability in MIG-P, four packets of pulse parameters were analysed: Ip = 160 A, tp = 5.7 ms; Ip = 300 A and tp = 2 ms, Ip = 350 A, tp = 1.2 ms and Ip = 350 A, tp = 0.8 ms. Each was analyzed with three different drop diameters: drop with the same diameter of the wire electrode; droplet diameter larger drop smaller than the diameter of the wire electrode. For purposes of comparison the same was determined relation between the average current and welding speed was determined generating a constant (Im / Vs = K) for all parameters. Welding in flat plate by simple deposition for the MIG-P with a distance beak contact number (DBCP) constant was perfomed subsequently making up welding in flat plate by simple deposition with an inclination of 10 degrees to vary the DBCP, where by assessment on how the MIG-P behaved in such a situation was possible, in addition to evaluating the MIG-P with adaptive control, in order to maintain a constant arc stability. Also high speed recording synchronized with acquiring current x voltage (oscillogram) was executed for better interpretation of the transfer mechanism and better evaluation in regard to the study of the stability of the process. It is concluded that parameters 3 and 4 exhibited greater versatility; diameters drop equal to or slightly less than the diameter of the wire exhibited better stability due to their higher frequency of detachment, and the detachment of the drop base does not harm the maintenance the height of the arc

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Brazilian constitution says that all Brazilians have basic survival rights such as education, sanitation and food, but these basic rights are luxury for some. So, thinking about this, this paper aims to develop a critical analysis about the (re)production of the discourse on poverty, and consequently on the poor, given by the federal government, through the official website of the program Brazil Without Poverty (Brasil Sem Pobreza), the media, represented by Veja magazine, and by those who affirm to be representatives of the poor; like the Single Central Slums (Central Única das Favelas CUFA). Our aim is to present a critical reflection on the discourses about the poverty in the voices of the government, Veja magazine (media representative) and CUFA (poor representative) and their contribution to the development of the meanings of the theme in Brazilian society. In order to do so, we have identified categories based upon Bajoit (2006a) to classify which the author calls faces of poverty . We have used the Sociological and Communicational Discourse Approach (ASCD) as developed by Pedrosa (2012a, 2012b, 2012c), within the Critical Discourse Analysis as theoretical apparatus, and also the studies in which the ASCD is built upon such as Sociology for Social Change (BAJOIT, 2006), the Cultural Studies (HALL, 2005), and the Functional Systemic Linguistic, especially the Evaluating System (MARTHIN & WHITE, 2005, VIAN JR et al, 2011). Thus, the discourse on poverty or on fighting poverty, extracted from news, chronicles and other genres of the mentioned vehicles, are taken as object of study to understand identities that are created and renewed on poverty and on the Brazilian poor, as their dependence on the government and civil society, their exploitation by the economy, and even the media that sometimes features them as delinquent

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O objetivo deste trabalho é divulgar, por meio de uma tradução comentada, um dos principais trabalhos escritos por Dominique François Jean Arago (1786-1853) relativo ao eletromagnetismo. Trata-se de uma descrição das experiências feitas por ele, relativas à magnetização do ferro e do aço pela ação da corrente voltaica.

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

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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This work reports the separation of phenolic compounds present in the metabolic extract of the lichen Neuropogon aurantiaco-ater (Usniaceae). The crude extract was fractionated by droplet counter-current chromatography using a solvent mixture of high polarity (chloroform:methanol:water at 43:37:20, in ascending mode). The separation resulted in the isolation of usnic and protocetratic acid, which were identified by TLC, HPLC, and NMR tests.

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Electric propulsion is now a succeful method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Thruster, so called Hall Thruster or SPT (Stationary Plasma Thruster), was primarily conceived in USSR (the ancient Soviet Union) and, since then, it has been developed by space agencies, space research institutes and industries in several countries such as France, USA, Israel, Russian Federation and Brazil. In this work we present the main features of the Permanent Magnet Hall Thruster (PMHT) developed at the Plasma Laboratory of the University of Brasilia. The idea of using an array of permanent magnets, instead of an electromagnet, to produce a radial magnetic field inside the plasma channel of the thruster is very significant. It allows the development of a Hall Thruster with power consumption low enough to be used in small and medium size satellites. Description of a new vacuum chamber used to test the second prototype of the PMHT (PHALL II) will be given. PHALL II has an aluminum plasma chamber and is smaller with 15 cm diameter and will contain rare earth magnets. We will show plasma density and temperature space profiles inside and outside the thruster channel. Ion temperature measurements based on Doppler broadening of spectral lines and ion energy measurements are also shown. Based on the measured plasma parameters we constructed an aptitude figure of the PMHT. It contains the specific impulse, total thrust, propellant flow rate and power consumption necessary for orbit raising of satellites. Based on previous studies of geosyncronous satellite orbit positioning we perform numerical simulations of satellite orbit raising from an altitude of 700 km to 36000 km using a PMHT operating in the 100 mN - 500 mN thrust range. In order to perform these calculations integration techniques were used. The main simulation paraters were orbit raising time, fuel mass, total satellite mass, thrust and exaust velocity. We conclude comparing our results with results obtainned with known space missions performed with Hall Thrusters. © 2008 by the American Institute of Aeronautics and Astronautics, Inc.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)