Electrical Circuits
Mostrando 25-36 de 95 artigos, teses e dissertações.
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25. Comportamiento del tiempo de duración, la frecuencia de los cortocircuitos y la conductividad eléctrica durante el reencendido del arco en la soldadura SMAW (AC) con electrodos E6013
The objective of this work is the valuation of the behavior of short-circuits frequency and duration time and electrical conductivity on arc reigniting in SMAW (Shielded Metal Arc Welding) process with alternate current and E6013 electrodes. The non parametric statistic analysis realize a robust data processing, minimizing the outliers influence and mistakes
Soldagem & Inspeção. Publicado em: 2009-03
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26. Desenvolvimento e aplicações de sensores de campo magnético por indução : [dissertação]
This work addresses the development of magnetic elds meters at low frequencies. The sensing elements used are induction coils and the Chattock-Rogowski coils, both with non-ferromagnetic cores. Theoretical and experimental studies on the working principle of these sensors are presented, considering the practical aspects related to their non-ideal behavior. T
Publicado em: 2009
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27. Sistema para corrosão anisotropica profunda de sensores microeletromecanicos / Anisotropic etching system for micro electrical mechanical sensor
Integrated Silicon Sensors and Microelectromechanical Systems (MEMSs) have been developing drived mainly by the micro and nanoelectronic industry s continuous growth. As a result, MEMSs have been spreading out very quickly into commercial products. In fact, MEMSs have undertaken room in automotive market where pressure sensors as well as accelerometers have
Publicado em: 2009
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28. Electrical system fault based on the resulting magnetic signature by Wavelet. / Análise da assinatura magnética resultante de faltas em sistemas elétricos via wavelets.
A methodology based on the analysis of magnetic fields for monitoring the quality of energy in electrical systems is presented herein. Aspects referring to fault detection in electrical systems in particular are evaluated. Contrary to the traditional monitoring process, in which sensors must be physically linked to the circuits under analysis, the results ar
Publicado em: 2009
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29. SistemÃtica para identificaÃÃo de nÃo-conformidades e proposiÃÃo de aÃÃes mitigadoras contra incÃndio em transformadores de potÃncia
In an electrical system, fires in power transformers, normally, cause great upheavals and high loss to the electric energy companies, to the society, to the environment and, in a considerable way, to the productive process. The transformers have an important role in an electrical system of power. Located in substations, and being the most expensive and impor
Publicado em: 2009
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30. A new technique for interrogating fiber optic sensors with Bragg gratings / Uma nova tecnica para interrogação de sensores a fibra otica com grades de Bragg
The recent advances in fiber optics and eletronic circuits has led to the development of many sensors based on fiber optics, with a great emphasis on Fiber Bragg Gratings (FGB) sensors. The FGBs sensors are used to quantify severeal measurands, as temperature, pressure, tension, thermodynamics and electrical current, with good accuracy and resolution. In thi
Publicado em: 2009
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31. SYNTHESIS METHODOLOGY FOR SIMPLIFIED ZVT TOPOLOGIES APPLIED TO BIDIRECTIONAL PWM POLES / METODOLOGIA DE SÍNTESE DE TOPOLOGIAS ZVT SIMPLIFICADAS APLICADAS A PÓLOS PWM BIDIRECIONAIS
Among the soft-switching techniques, the zero-voltage-transition (ZVT) technique has been accepted well by the industry due its attractive characteristics, such as simplicity, low losses in the auxiliary commutation circuit (ACC), operation with soft-switching for a wide load range, and closest operation to the PWM converter counterpart. In three-phase volta
Publicado em: 2009
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32. Preparação e caracterização estrutural e elétrica de cristais mistos de K1-x(NH4)xH2PO4
The preparation and structural and electrical characterization of KH2PO4 (KDP), (NH4)H2PO4 (ADP) and K1-x(NH4)xH2PO4 (KADPx) mixed crystals grown by the method of solvent evaporation at 40 C and with x = 0, 0.076, 0.118, 0.357, 0.857, 0.942, 1.0 was carried out. Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) was performed in order to deter
Publicado em: 2009
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33. "Afundamentos de tensão no contexto da expansão dos sistemas elétricos: proposta de índices considerando dados do sistema de detecção de descargas atmosféricas"
The impact of voltage sags to power utilities and consumers has been remarking this event as a relevant phenomenon to address in power system studies. It is considered one of the most frequent sources of power-supply interruption and malfunction on several types of equipment, resulting in power-quality degradation. Nowadays, voltage sag has been basically ad
Publicado em: 2009
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34. Evaluation and modelling of integral capacitors produced by interdigitated comb electrodes
Integral capacitors (IC) of one or two-layer printed wiring board (PWB) circuits were produced using comb electrodes fixtures and dielectric composites as the inter-electrode material. ICs were fabricated at laboratory scale, using copper comb electrodes and BaTiO3-epoxy composite materials deposited on a glass-Epoxy FR4 board. They were experimentally teste
Materials Research. Publicado em: 2008-12
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35. Influence of intensive light exposure on the complex impedance of polymer light-emitting diodes
In this work we investigated the effect of visible radiation on the electrical properties of poly[(2-methoxy-5-hexyloxy)-p-phenylenevinylene]- MH-PPV films and light emitting diodes. Complex impedance measurements of (Au or ITO)/MH-PPV/(Au or Al) samples were carried out at room temperature and exposed to white light. Over the frequency range from 100 mHz to
Materials Research. Publicado em: 2008-06
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36. Como sobrevivem as diferentes noções de álgebra linear nos cursos de engenharia elétrica e nas instituições
This research included in the current project called In Search of propitious situations for learning basic concepts of Linear Algebra of Group s Studies of Education Algebraic (GPEA) of the Pontifical Catholic University of São Paulo (PUC-SP), proposes find elements that meet issues inherent in this research: Why and how should be tauch the discipline Linea
Publicado em: 2008