Electrical Circuits
Mostrando 37-48 de 95 artigos, teses e dissertações.
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37. A matemática e os circuitos elétricos de corrente contínua: uma abordagem analítica, prático-experimental e computacional
Este trabalho trata do desenvolvimento de um material didático, sob a forma de cadernos (presentemente, em forma de capítulos), acompanhado de protótipo de circuito simples para testes experimentais, a ser utilizado no ensino de nível médio. O conteúdo reunido nos cadernos abrange o desenvolvimento analítico de tópicos pertinentes à física-matemát
Publicado em: 2008
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38. Development of MEMS switch device technology MEMS - MicroelectromechanicalSystems - for RF - radio frequency - and new topologies of RF CMOS integrated circuits for radio receivers input sub-systems / Desenvolvimento de tecnologia de dispositivos chaves MEMS - MicroelectromechanicalSystems - para RF - Radio Frequencia - e novas topologias para circuitos integrados CMOS de RF em sub-sistemas de entrada de radio receptores
Este trabalho apresenta dois tópicos de pesquisa, o primeiro é referente ao projeto e desenvolvimento da tecnologia de fabricação de Chaves MEMS (Micro Electro Mechanical System) de RF e o segundo é o projeto de circuitos integrados. No que se refere a chaves MEMS, descreve-se o processo e a metodologia para projeto de Chaves MEMS paralela sobre linha d
Publicado em: 2008
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39. INVERSORES ZCZVT COM ACOPLAMENTO MAGNÉTICO: SÍNTESE E ANÁLISE.
This Ph. D. Thesis presents a in deep study of the mechanism of resonant transition soft-switching techniques. By means of the principles that rules the PWM resonant transition converters, a novel tool for analysis and synthesis have been developed. This novel tool also permit to be verified some of the main factors that made possible to he ZVT technique to
Publicado em: 2008
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40. CORROSION OF ADVANCED STAINLESS STEEL IN PHYSIOLOGICAL SOLUTIONS / Corrosão de aços inoxidáveis avançados em meios fisiológicos
The main objective of this study was to determine the corrosion behavior of advanced stainless steels (SS) in physiological solutions to evaluate their potential for use as biomaterials. Four stainless steels were tested: a superferritic stainless steel (DIN W. Nr. 1.4575), Incoloy MA 956, containing aluminum and yttrium oxide, an austenitic stainless steel
Publicado em: 2008
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41. Medição de impedância utilizando sistemas digitais
Conducting measurements is, in the most part of practical situations, essential for scientific research. It is so important, that it can be said, that all areas in engineering are dependent of it. As well known, impedance measurement is a subject of great interest in many application fields, each of which has different demands in terms of accuracy, range, me
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 12/06/2007
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42. Exploração de reordenamento de ROBDDs no mapeamento tecnológico de circuitos integrados / Exploration of ROBDD reordering on technology mapping for integrated circuits
The ROBDDs are structures that have been successfully used in CAD tools for microelectronics. These structures allow canonical representation of boolean functions when established a fixed variable ordering. In the context of an automatic logic cell generator for integrated circuits, ROBDDs may serve as a base for deriving transistor networks from which elect
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 2007
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43. Monitoramento permanente de motores de indução trifasicos / On-line monitoring of three-phase induction motors
A predictive maintenance program must include several techniques of monitoring of the electric motors conditions. Among these techniques, probably the two most classic ones are related to electric current and vibration analysis. Unfortunately, in both cases inherent drawbacks make difficult their use in loco on industry plants. As there is a large range of
Publicado em: 2007
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44. Modeling and optimization of piezoelectric shunts apply to passive vibration control / Modelagem numérica e otimização de shunts piezelétricos aplicados ao controle passivo de vibrações
Due to the development of new technologies, industrial structures are now made of lighter materials and work at higher operation speeds producing an increasing vibration and noise level generation. As a result, different techniques of active and passive control have been developed and are continuously being improved. Among the passive control techniques, the
Publicado em: 2007
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45. Preparação de resinas de poliuretana à base de óleo de mamona e dietanolamina
The aim of this work was the preparation of polyols from reactions between castor oil and dietanolamine to increase the hydroxyl content and the network degree in the products to application in electronic devices. The polyols and the mixtures obtained were characterized by nuclear magnetic ressonance. Castor oil (CO) is a natural triglyceride - based polyol
Publicado em: 2007
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46. Study of charge transport layers in polymer light emitting diodes. / Estudo de camadas transportadoras de cargas em diodos emissores de luz poliméricos.
In the present work, the study of the optical and electrical properties of polymeric electroluminescent devices known as Polymer Light-Emitting Diodes (PLEDs) and the development of Hole Transport Layers (HTLs) to promote an increase of the electrical efficiency of the devices was performed. PLEDs were constructed with structures like Anode/HTL/Electrolumine
Publicado em: 2007
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47. Sistema computadorizado para preparo e aplicação de soluções nutritivas com base na estimativa da transpiração do tomateiro cultivado em casa de vegetação / Computer system for preparing and applying nutrient solutions with base on the transpiration estimate of tomato cultivated in greenhouse
In soilless and hydroponic culture, continuous monitoring and frequent adjusts of the fertilizer concentration in nutrient solution to be delivered are essential to optimize plant growth. In this work, low cost electronic circuits were proposed, calibrated and validated for real time measurements of electrical conductivity from 0.10 to 10.15 dS m-1 and tempe
Publicado em: 2007
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48. Sensitivity analysis of secondary arc current for different transmission lines / Analise de sensibilidade da corrente de arco secundario para diferentes linhas de transmissão
The secondary arc appears in single-phase switching during clearing of non-permanent ground single-phase to ground faults. The problem happens especially on EHV lines, on aerial isolation, in faults with non permanent characteristics. In this work different transmission lines with voltage levels of 345 kV up to 765 kV and with 150 km up to 900 km length are
Publicado em: 2007