Magnetic Losses
Mostrando 13-24 de 49 artigos, teses e dissertações.
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13. SÍNTESE E CARACTERIZAÇÃO DE NiFe2O4 E EFEITOS DA DOPAGEM NA MAGNETIZAÇÃO DE SATURAÇÃO. / SYNTHESIS AND CHARACTERIZATION OF NiFe2O4 AND EFFECTS OF DOPING IN MAGNETIC SATURATION.
The ferrites are a wide class of ferrimagnetic materials with great technological importance and are studied extensively for many decades. Their remarkable magnetic characteristics make it an element often used in induction transformers by his high magnetic permeability, high values of saturation magnetization and low coercivity, resulting in smaller losses
Publicado em: 2011
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14. A influência do recozimento descarbonetante nas propriedades magnéticas de aços para fins elétricos. / The influence of decarburizing annealing on magnetic properties of electrical steels.
Este trabalho analisa o efeito da descarbonetação nas perdas magnéticas de aços elétricos semiprocessados, após recozimento final, descarbonetante e/ou não-descarbonetante. Neste trabalho foi utilizado um aço de baixo carbono (600ppm de C) encruado a 4-6% de deformação, tipo COSCORE 55O. Foi notado que o recozimento descarbonetante reduz rapidament
Publicado em: 2011
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15. Design and test of HTS coils for resistive fault current limiter
This paper presents the design, manufacturing and test results of HTS coils for single-phase resistive current limiters using two different Bi-2223/Ag tapes. Two coils were separately wound on cylindrical G-10 tubes with helical path. One of the coil was wound in a bifilar conductor arrangement aiming at reducing the self-inductance. The maximum flux density
Publicado em: 2011
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16. Avaliação da influência da temperatura e ponto de orvalho no recozimento final de aços elétricos semiprocessados e totalmente processados / Evaluation of the influence of final annealing heat treatment temperature and dew point in semi-processed and fully processed electrical steels
Semi-processed electrical steels require annealing after processing in the motors manufactures to improve motors efficiency by reducing losses and increasing permeability. Annealing in fully processed electrical steel is performed to relax the residual stress and promote recovery or recrystallization of distorted parts. Commercial samples from different stee
Publicado em: 2010
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17. Oxygen potencial effects on the oxidation sublayer and its influence on the magnetic properties of eletric steels after the final annealing heat treatment. / O efeito do potencial de oxigênio na oxidação subsuperficial e suas influências nas propriedades magnéticas de aços elétricos após o recozimento final.
Semi processed electrical steels, used for the manufacture of rotor and stator laminations are acquired from Steel Markers and after being punched in its final shape, must undergo an annealing heat treatment, which aims to improve the magnetic properties of the steel. If this heat treatment is carried out under inappropriate conditions, the dissolved element
Publicado em: 2010
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18. Perdas em ferritas de manganês zinco: o papel da sinterização e de parâmetros microestruturais. / Magnetic losses in maganese zinc ferrites: the role of sinterization and microstructural parameters.
O uso das ferritas de manganês zinco em fontes de potência de carregadores de bateria vem crescendo nos últimos anos, devido a suas baixas perdas magnéticas em induções da ordem de 0,2 T. Estas ferritas pertencem à categoria de ferritas moles, são óxidos ferrimagnéticos, policristalinos com estrutura cúbica tipo espinélio. Pós desse material for
Publicado em: 2010
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19. Modelagem da precipitação de MnS em aços elétricos de grão orientado
Grain oriented silicon steel has been used for electrical purposes since the beginning of the twentieth century. Their properties such as high permeability and resistivity reduce energy losses. The high permeability of these steels arises from a preferred orientation of grains in relation to the direction of rolling which leads to strong anisotropy of the ma
Publicado em: 2010
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20. Paramagnetic shimming for high-field MRI
The diamagnetism of biological tissues reduces the homogeneity of the magnetic field and may limit the number of samples in multi-sample gradient-recalled echo (GRE) experiments. This study aims to 1) evaluate the magnetic field distortions and signal loss artifacts in GRE images of proximal water samples, and 2) develop a passive shimming device to overcome
Brazilian Journal of Physics. Publicado em: 2009-06
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21. ANÁLISE, MODELAGEM E VALIDAÇÃO EXPERIMENTAL DE UMA METODOLOGIA PARA O PROJETO DO INDUTOR EM CONVERSORES BOOST PFC / ANALYSIS, MODELING AND EXPERIMENTAL VALIDATION OF A DESIGN METHODOLOGY FOR THE INDUCTOR IN PFC BOOST CONVERTERS
This work presents the development of a methodology for design of inductor in singlephase PFC boost converters operating in CCM mode in agreement with international standards IEC 61000-3-2 and CISPR 22. Such converters are used in front-end modules of information technology equipment. This methodology is based on the investigation of the relationship among m
Publicado em: 2009
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22. PurificaÃÃo e identificaÃÃo de substÃncias de Chrysophyllum gonocarpum (Mart &Eichler) Engl ativas contra o bicho mineiro do cafeeiro / Purification and identification of substances from Chrysophyllum gonocarpum (Mart. &Eichler) Engl. active against the coffee leaf miner.
Since the coffee leaf miner causes plantation defoliation that accounts for losses in coffee production, this insect is considered a very important pest in coffee farms. Thus, the present study aimed to contribute to the development of new insecticides of plant origin to control such insect. Consequently, a phytochemical study about leaves of Chrysophyllum g
Publicado em: 2009
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23. Geomagnetic DST index forecast using artificial neural networks and decision tree / Previsão do índice geomagnético dst utilizando redes neurais artificiais e árvore de decisão
The Earth suffers constant influence of the solar activity through the solar wind, which brings with it the resulting structures, mainly phenomena like solar flares and coronal mass ejection. The almost static interaction between the solar wind and the geomagnetic field forms a structure called magnetosphere, which acts as a shield that protects the planet f
Publicado em: 2009
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24. Estudo das propriedades estruturais e elÃtricas das granadas ferrimagnÃticas GdIGXYIG1-X e suas aplicaÃÃes em componentes de microondas. / Study of the strutural and electric properties of garnets ferrimagnetc GdIGXYIG1-X and its aplications in componentes of microwaves.
Due to a fast progress in the development of communication systems, the dielectric and magnetic ceramics (ferrites) have become attractive to be used in devices. Although the ferrites of the spinel type were the first material used in the microwave range, garnets have smaller dielectric losses and, therefore, are chosen for many applications. High demands fo
Publicado em: 2008