920 research outputs found
Manejo e manutenção da biodiversidade da floresta secundária dentro da agricultura familiar na Amazônia Oriental brasileira.
Theoretical and experimental investigation of performance characteristics and design aspects of cross-spring pivots
Cross-spring pivots have been widely employed over the last decades in a broad variety of precision engineering applications due to the high motion repeatability achieved thanks to the absence of stick slip and clearance. In this paper, the non-linear effect of the anticlastic curvature of the leaf-springs is considered for the accurate analytical modeling of the elasto-kinematic behavior of cross-spring pivots. Finite element analyses (FEA), based on a non-linear thin-shell model, are carried out in order to compare them with the analytical results for the main performance parameters of this type of device, i.e. center-shift, rotational stiffness and stress in the leaf-springs. Furthermore, an experimental setup is built to assess the applicability limits of both models. Finally, remarkable performance aspects of cross-spring pivots are discussed aiming for design improvements
Aspecto biofísico de vegetação secundária enriquecida com leguminosas de rápido crescimento no nordeste do Pará: composição espectral da luz.
Prospecção de espécies vegetais potencialmente acumuladoras de fósforo: uma estratégia para a melhoria da sustentabilidade de sistemas agroflorestais seqüenciais no nordeste Paraense.
Cópia de trabalho editado em CD-ROM
Environmental effects on cattle and buffaloes in cultivated pasture of Marajo Island, Brazil.
Relações entre variáveis fisiológicas e de ambiente físico em zebuínos e bubalinos na Ilha de Marajó.
Toxicity to cotton boll weevil Anthonomus grandis of a trypsin inhibitor from chickpea seeds.
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