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Elephant grass is a perennial tropical grass with great potential for energy generation from biomass. The objective of this study was to estimate the genetic diversity among elephant grass accessions based on morpho-agronomic and biomass quality traits and to identify promising genotypes for obtaining hybrids with high energetic biomass production capacity. The experiment was installed at experimental area of the State Agricultural College Antônio Sarlo, in Campos dos Goytacazes. Fifty-two elephant grass genotypes were evaluated in a randomized block design with two replicates. Components of variance and the genotypic means were obtained using a Bayesian multi-trait model. We considered 350,000 iterations in the Gibbs sampler algorithm for each parameter adopted, with a warm-up period (burn-in) of 50,000 Iterations. For obtaining an uncorrelated sample, we considered five iterations (thinning) as a spacing between sampled points, which resulted in a final sample size 60,000. Subsequently, the Mahalanobis distance between each pair of genotypes was estimated. Estimates of genotypic variance indicated a favorable condition for gains in all traits. Elephant grass accessions presented greater variability for biomass quality traits, for which three groups were formed, while for the agronomic traits, two groups were formed. Crosses between Mercker Pinda México x Mercker 86-México, Mercker Pinda México x Turrialba, and Mercker 86-México x Taiwan A-25 can be carried out for obtaining elephant grass hybrids for energy purposes.

This paper presents a comprehensive study towards the determination of efficient pole-arc coefficients for axial flux permanent magnet (PM) machines, through investigation of the contribution of volume elements of PMs to the no load flux linkage. The proposed methodology involves the evaluation of flux linkage using a mathematical expression which integrates a function over the volume of PMs instead of the classical integration of the magnetic flux density over the coil surface. The process is implemented using 2D finite element (FE) analysis, and the results shows the pole-arc coefficients that maximize the ratio of the flux linkage over the PM volume is between 0.5 and 0.6.

Os materiais magnéticos permanentes têm sido utilizados em dispositivos eletromagnéticos há mais de 100 anos mas, devido aos rogressos recentes das suas características magnéticas e a disponibilidade a custos acessíveis, a sua aplicação é atualmente transversal a uma vasta gama de áreas tecnológicas. A introdução dos ímanes de terras raras nos finais da década de 60 do século passado revolucionou a engenharia de projeto, conduzindo a uma reconfiguração dos dispositivos com fatores de escala anteriormente impraticáveis, elevando ainda o rendimento daqueles, ao eliminar as perdas associadas à criação de campos magnéticos baseados em densidades de correntes. Este trabalho descreve as principais classes dos materiais magnéticos permanentes com relevância comercial e fornece as linhas gerais do projeto magnético, com especial relevo para os materiais baseados em terras raras.

Small-scale wind power applications require a cost effective and mechanically simple generator in order to be a reliable energy source. The use of direct driven generators, instead of geared machines, reduces the number of drive components, which offers the opportunity to reduce costs and increases system reliability and efficiency. For such applications, characterized by low speed of rotation, the axial flux permanent magnet generator is particularly suited, since it can be designed with a large pole number and high torque density. This paper presents an axial flux permanent magnet synchronous generator, double sided with internal rotor and slotted stators. Such a structure gives a good compromise between performance characteristics and feasibility of construction. The design process of the machine is described and validated by test experiments.

Os materiais magnéticos permanentes desempenham um papel preponderante numa vasta gama de produtos industriais e de consumo. O recente desenvolvimento dos ímanes de terras raras e a sua vulgarização introduziram alterações profundas nos dispositivos electromagnéticos e electrónicos com consequências no desempenho, tamanho e configuração, assim como na redução do custo dos produtos finais de uma forma que não era previsível há apenas 30 anos. A proliferação destes materiais tem ainda estimulado o desenvolvimento de novos produtos e mercados. Este trabalho constitui uma sinopse dos principais aspectos relacionados com os materiais magnéticos permanentes: é apresentada uma perspectiva histórica da sua evolução e uma compreensão básica da teoria do magnetismo. As tecnologias de fabrico e as principais classes de ímanes permanentes comerciais encerram a discussão.

In low speed applications such as wind energy conversion systems, the use of direct driven generators, instead of geared machines, reduces the number of drive components, which offers the opportunity to reduce costs and increases system reliability and efficiency. The Axial Flux Permanent Magnet (AFPM) generator is particularly suited for such application, since it can be designed with a large pole number and a high torque density. This paper presents the design, construction and experimental validation of a double-sided AFPM synchronous generator prototype, with internal rotor and slotted stators. Design objectives embrace achieving a good compromise between performance characteristics and feasibility of construction, which results in a cost competitive machine.

Small scale wind power applications require a cost effective and mechanically simple generator in order to be a reliable energy source. The use of direct driven generators, instead of geared machines, reduces the number of drive components, which offers the opportunity to reduce costs and increases system reliability and efficiency. For such applications, characterized by low speed of rotation, the axial flux permanent magnet generator is particularly suited, since it can be designed with a large pole number and high torque density. This paper presents a double-sided axial flux permanent magnet low-speed generator, with internal rotor and slotted stators. Such a structure gives a good compromise between performance characteristics and feasibility of construction. Test results obtained from the prototype are reported. FCT