The Wind Energy Conversion System (WECS) is a nonlinear system

It is necessary at least two or more independent known vectors for attitude determination of an artificial satellite. One of these vectors can be the Earth Magnetic Field, which is used as reference in navigation for centuries. Other reference can be the sun, which is easily distinguished of other astronomical objects in the proximities of the Earth. While the Earth Magnetic Field can be measured by a small solid-state three-axis magneto-resistive transducer, the own photovoltaic system of the artificial satellite can provide a evaluation of the azimuthal position of the sun. This paper presents a way to estimate the sun position from the own satellite power system. This information is used for attitude determination, allowing the integration of two important subsystems of an artificial satellite.

Supplier evaluation and selection is one of the most important processes to achieve an efficient supply chain. It is usually regarded as a multiple critera decision-making (MCDM) problem. Data on the whole supply chain, including the purchasing process is now easily available. This paper proposes a methodology that defines indices of performance of suppliers, based on real data, and ranks them by the heuristic VIKOR method. The ratings reflect reliability, mean delivery time, and percentage of orders shipped to buyer on or before original promised ship date. The methodology was validated using principal components analysis, followed by k-means clustering and biplots to help in labeling and interpreting the clusters. The overall conclusion is that the proposed methodology is capable of choosing suppliers that will result in increased supply chain efficiency, due to decreased lead times and lower operational costs of the purchasing process. Resumo: A avaliação e seleção de fornecedoresé um dos processos mais importantes para se obter uma cadeia de suprimentos eficiente, sendo considerado um problema de tomada de decisão multi-critérios. Os dados de cadeias de suprimentos, incluindo o processo de compras, agora estão facilmente disponíveis. Este trabalho propõe uma metodologia que defineíndices de desempenho de fornecedores, com base em dados reais, e ranqueia-os pelo método heurístico VIKOR. Os ratings refletem a confiabilidade, a média de tempos de entrega e a média de prazos originais prometidos de envio ao comprador. A metodologia foi validada usando análise por componentes principais, seguida por clusterização k-means e biplots para ajudar na rotulagem e interpretação dos clusters. A conclusão geralé que a metodologia propostaé capaz de escolher fornecedores que resultarão em maior eficiência da cadeia de suprimentos, devidoà redução de leadtimes e a menores custos operacionais dos processos de compras.

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