1000 resultados para Recherche à voisinage variable


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El objetivo del presente trabajo de investigación es arrojar luz sobre los factores que explican la menor intencionalidad en la población femenina para involucrarse en procesos de creación de empresas. Para ello, se ha desarrollado un modelo de ecuaciones estructurales que identifica un conjunto de variables que permiten explicar la intención de emprender en la población potencialmente emprendedora. La validación del modelo se ha realizado mediante una encuesta realizada a 1222 estudiantes de 12 titulaciones diferentes de la Universidad de Málaga. La aplicación del modelo a las poblaciones masculina y femenina ha permitido apreciar diferencias significativas en los patrones de comportamiento en función del género, identificando un proceso más complejo y necesitado de apoyo externo en la población femenina con respecto a la masculina.

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Modern wind turbines are designed in order to work in variable speed opera-tions. To perform this task, these turbines are provided with adjustable speed generators, like the double feed induction generator (DFIG). One of the main advantages of adjustable speed generators is improving the system efficiency compared with _xed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However, this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. The proposed design also uses the vector oriented control theory in order to simplify the DFIG dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and pa-rameter uncertainties using the Lyapunov stability theory. Finally, the simulated results show on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, which usually appear in real systems.

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Presentado en el 13th WSEAS International Conference on Automatic Control, Modelling and Simulation, ACMOS'11

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Modern wind turbines are designed in order to work in variable speed operations. To perform this task, wind turbines are provided with adjustable speed generators, like the double feed induction generator. One of the main advantage of adjustable speed generators is improving the system efficiency compared to fixed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. An integral sliding surface is used, because the integral term avoids the use of the acceleration signal, which reduces the high frequency components in the sliding variable. The proposed design also uses the vector oriented control theory in order to simplify the generator dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and parameter uncertainties by using the Lyapunov stability theory. Finally simulated results show, on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, that usually appear in real systems.

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EFTA 2009