22 resultados para Transistores bipolares
em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Este artigo apresenta valores eletrocardiográficos de 25 bezerros da raça Holandesesa, utilizando-se as derivações bipolares de membro (I, II, III), unipolares aumentadas de membro (avL, avR e avF) e uma derivação bipolar de torax (V10). Dois grupos com animais de diferentes idades foram comparados (18 a 72 horas e 27 a 33 dias de idade). Conclui-se que não houve diferença significativa entre os grupos nas ondas P, Q, R, S e T, nos intervalos PR, QRS, QT e ST e no eixo cardíaco.
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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)
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Pós-graduação em Ciência e Tecnologia de Materiais - FC
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Pós-graduação em Geociências e Meio Ambiente - IGCE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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During the twentieth century the inorganic electronics was largely developed being present in various industrial equipment or household use. However, at the end of that century were verified electronic properties in organic compounds, giving rise to the field of organic electronics. Since then, the physical properties of elementary devices such as diodes and organic transistors have been studied. In this work was studied the properties of diode devices fabricated with a semiconductor polymer, the poly-o-methoxyaniline (POMA). Devices containing electrodes of Au and Al were fabricated with semiconductor polymer of different doping levels. We found that the rectifying behavior for the heterojunctions metal/polimer are reached only for high doping level (with conductivity greater than 1,77. 10-9 S / cm), which gives the devices characteristic of a Schottky diode. The rectifying behavior was observed for electric fields of low magnitude, below the operating field (~ 600 V/cm), while for electric field greater than 600 V/cm the a linear behavior I vs.V was obtained. We determined that this Ohmic behavior arises from the charge transport over the volume of the semiconductor material after the lowering of the metal/semiconductor barrier. In devices with weakly doped semiconductor, the electrical resistance of the volume becomes high and the process of charge transportation is dominated by the volume, for any intensity of the applied electric field
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Due to concerns about rational use of energy, several alternative technologies of power generation appeared, including the conversion of solar energy into electrical energy by photovoltaic panels. In low-income households, the refrigerator represents considerable impact on the electric bill, since it requires constant power given its use in food preservation. It is possible to reduce this share, with the use of an alternative energy source. This work presents a timed switching electronic system, which allows commercial equipment that is not affected by short interruptions in the power supply to use a photovoltaic panel as a source of alternative energy, which usually do not provide energy continuously. Switching is made automatically in case of low incidence of sunlight, and without any form of energy storage. Between each switching, there is a dead time without power supply, therefore preventing the use of synchronizers circuits between the photovoltaic panel and the public power grid. A circuit containing a 80C31 microcontroller is used to control the system’s switching. The photovoltaic panel’s voltage inverter is in H bridge configuration, and is also controlled by the microcontroller through Pulse Width Modulation, which makes use of preprogrammed tables to generate the control signals of the power transistors. Through the use of software simulations, the proposed system was tested, which is capable of supplying intermittent single-phase loads. The simulations indicates that the project developed in this paper can be assembled into a prototype and be tested under real operating conditions, as long as the scaling of components, the characteristics of the photovoltaic panel to be used, and the project involved load are taken into account
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The objective of this study is to discuss the notion of history in Arendt, from the importance that needs the thought of Duns Scotus, particularly with regard to the primacy of the will. For the author, Scotus was a medieval thinkers to emphasize the role of free will as power in the face of intellect attached to the natural activity. The freedom to get an act featuring a world ruled by contingency. Now, for Arendt, that freedom is consistent with your idea of authentic political, and base a public space, defined by word and action of individuals. The history, which takes place from political activity, received various treatments, from Greek antiquity to the modern conception of process. It joined the idealistic conceptions, establishing universal ways of defining the future. However, if freedom is to characterize the vita activa, the history must seek the meaning of the facts to scrutinize their singular aspects, which fell to the continuo of universal explanation of the official history. It is, therefore, to approach the history from the perspective of singular narrative, from the spectators, those who founded the public space. Hence the importance of bipolar concepts such as nature and freedom, necessity and contingency, will and intellect, as Scotus.
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Pós-graduação em Engenharia Elétrica - FEIS
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)