Conversor CA-CA de elevado fator de potência para aplicações com geradores de Ímã permanente

This paper proposes and describes a high power factor AC-AC converter for naval applications using Permanent Magnet Generator (PMG). The three-phase output voltages of the PMG vary from 260 Vrms (220 Hz) to 380 Vrms (360 Hz), depending on load conditions. The proposed converter consists of a Y-/ΔY power transformer, which provides electrical isolation between the PMG and remaining stages, and a twelve-pulse uncontrolled rectifier stage directly connected to a single-phase inverter stage, without the use of an intermediary DC-DC topology. This proposal results in more simplicity for the overall circuitry, assuring robustness, reliability and reduced costs. Furthermore, the multipulse rectifier stage is capable to provide high power factor and low total harmonic distortion for the input currents of the converter. The single-phase inverter stage was designed to operate with wide range of DC bus voltage, maintaining 120 Vrms, 60 Hz output. The control philosophy, implemented in a digital signal processor (DSP) which also contains protection routines, alows series connections between two identical converters, achieving 240 Vrms, 60 Hz total output voltage. Measured total harmonic distortion for the AC output voltage is lower than 2% and the input power factor is 0.93 at 3.6kW nominal load. © 2010 IEEE.

Avaliação comparada do uso de linguagens de indexação em catálogos de bibliotecas universitárias para recuperação por assunto

A comparative evaluation was made of the use of natural language versus two specialized indexing languages, aiming to demonstrate the influence of the availability of indexing languages on the functioning of information retrieval systems. The study was conducted within the ambit of the construction of search strategies by subject in online university library catalogs. The precision ratio was calculated to determine the accuracy of each indexing language in subjectbased information retrieval. From the comparative evaluation of the use of indexing languages, it was concluded that the term specificity required by the user during retrieval was more satisfactory when the query was made through controlled languages, whose availability and simplicity is also an indispensable requisite.

Fator de crescimento nervoso em cola de fibrina no reparo término-lateral de nervos em ratos

Purpose: To determine the effects of end-to-side nerve repair performed only with fibrin glue containing nerve growth in rats. Methods: Seventy two Wistar rats were divided into six equal groups: group A was not submitted to nerve section; group B was submitted to nerve fibular section only. The others groups had the nerve fibular sectioned and then repaired in the lateral surface of an intact tibial nerve, with different procedures: group C: ETS with sutures; group D: ETS with sutures and NGF; group E: ETS with FG only; group F: ETS with FG containing NGF. The motor function was accompanied and the tibial muscle mass, the number and diameter of muscular fibers and regenerated axons were measured. Results: All the analyzed variables did not show any differences among the four operated groups (p>0.05), which were statistically superior to group B (p<0.05), but inferior to group A (p>0.05). Conclusion: The end-to-side nerve repair presented the same recovery pattern, independent from the repair used, showing that the addition of nerve growth factor in fibrin glue was not enough for the results potentiating.

Relação entre o desempenho e período de recuperação após enfermidades ósseas do membro torácico distal de cavalos puro sangue inglês

It is well established in the literature that musculoskeletal injuries are important compromising agents in the performance of Thoroughbred horses. In Brazil, there are no studies on the interrelation between lay-up period post-injury and retirement of racehorses due to musculoskeletal injures. The aim of this study is to determine the relationship between rehabilitation times of track injures and variables of prior race performance and later return to competitions. The radiographic reports and athletic history of 416 thoroughbreds during the period between 2003 and 2006 were examined; they were selected based on continued presentations after injury diagnosis. The temporal variables (post-injury rehabilitation time) and performance variables (race score before and after injury) were evaluated by multivariate correspondence analysis of the data and represented in perceptual maps. Correspondence was observed between most of the animals that had a short lay-up post-injury and variables that denote decline in subsequent performance. Considering the integrity of the bone healing process as crucial for the horse to be able to handle later training routines and competitions, shortening this period could lead to an imbalance of the bone repair metabolism, thus resulting in performance decline and compromise of the horse athletic career.

Fator Pró-digestão inicial® e Isoterápico® na larvicultura da tilápia-do-Nilo: avaliação do índice de parasitismo, integridade hepática e branquial

Pós-graduação em Aquicultura - FCAV

Recuperação de perfis atmosféricos a partir de ocultação GPS: fundamentos, implementação e análise de resultados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Retificador boost entrelaçado com elevado fator de potência e sem ponte de diodos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Um novo sistema de refrigeração com controle de temperatura, compressor aberto, máquina de indução trifásica com velocidade variável e correção ativa do fator de potência do estágio de entrada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Célula de comutação de três estados aplicada ao pré-regulador boost de estágio único e elevado fator de potência

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Proposição de uma técnica de parametrização geométrica para o fluxo de carga continuado baseado nas variáveis tensão e fator de carregamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Exercício resistido em cardiopatas: revisão sistemática da literatura e análise do comportamento autonômico em recuperação pós-exercício resistido aplicado de forma aguda

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência de diferentes tipos de recuperação sobre a modulação autonômica cardíaca, concentração de lactato e proteína C-reativa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variabilidade da freqüência cardíaca como ferramenta de análise da função autonômica: revisão de literatura e comparação do comportamento autonômico e metabólico em recuperação pós-exercício

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O efeito de diferentes intervalos de recuperação entre as séries do treinamento com pesos, nas respostas neuromusculares e do hormônio do crescimento, em idosas treinadas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Respostas fisiológicas durante o exercício intervalado realizado no ciclismo com recuperação passiva e ativa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)