1,721,546 research outputs found
Estrategia de Control de Velocidad Indirecto para el Seguimiento del Punto Máximo de Potencia de un Sistema Eólico DFIG
Get PDFIn this In this article, a control strategy for Maximum Power Point Tracking (MPPT) of a wind turbine system based on a Doubly Fed Induction Generator (DFIG) is presented. The proposed strategy consists of the Indirect Speed Control (ISC) taking the Low Speed Shaft (LSS) as variable input. This implementation allows the MPPT to optimize the Power coefficient (Cp). The controller has been designed in order to allow the wind turbine to reach the MPPT along the partial load operation. For these experiments, a 1.5 MW wind turbine was modeled and simulated by using Matlab and Fatigue, Aerodynamic, Structure and Turbulence (FAST) software. In order to present the achieved results, a comparison between the ISC and a classical PI controller is made. The Cp curves as well as the output power display an important improvement in terms of stability. These results are possible because the appropriate values of optimal Tip Speed Ratio (TSR) and maximum Cp have been properly established. article, a control strategy for Maximum Power Point Tracking (MPPT) of a wind turbine system based on a Doubly Fed Induction Generator (DFIG) is presented. The proposed strategy consists of the Indirect Speed Control (ISC) taking the Low Speed Shaft (LSS) as variable input. This implementation allows the MPPT to optimize the Power coefficient (Cp). The controller has been designed in order to allow the wind turbine to reach the MPPT along the partial load operation. For these experiments, a 1.5 MW wind turbine was modeled and simulated by using Matlab and Fatigue, Aerodynamic, Structure and Turbulence (FAST) software. In order to present the achieved results, a comparison between the ISC and a classical PI controller is made. The Cp curves as well as the output power display an important improvement in terms of stability. These results are possible because the appropriate values of optimal Tip Speed Ratio (TSR) and maximum Cp have been properly established. En el siguiente artículo, se propone una estrategia de control para el seguimiento del punto máximo de potencia (MPPT) de un sistema de energía eólica con generador de inducción doblemente alimentado DFIG. La estrategia propuesta está basada en un Control de Velocidad Indirecto (ISC) tomando como entrada variable la velocidad baja del eje. Esta implementación permite realizar un seguimiento del MPPT de modo que el Coeficiente de Potencia (Cp) del sistema se optimice. El controlador ha sido diseñado para permitir que la turbina eólica alcance este punto máximo a lo largo de la zona de operación de carga parcial. Para realizar los experimentos, se seleccionó un aerogenerador de 1,5 MW y el modelo se implementó en una simulación por medio de Matlab y la aplicación de Fatiga, Aerodinámica, Estructuras y Turbulencia (FAST) para el análisis y posterior validación de resultados. La curva de Cp ha sido comparada con un controlador PI mostrando una mejora importante en términos de estabilidad y potencia activa de salida. Estos resultados son posibles debido a que se ha seleccionado apropiadamente los valores de Tip Speed Ratio TSR y Cp máximo
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Source Inverter Voltage and Frequency Control for AC Isolated Microgrid Applications
No full textA novel control strategy is proposed in this paper, which implements a Hierarchical Control (HC) and Space Vector Pulse Width Modulation (SVPWM). The paper outline includes the method design and its micro-grid performance, which has three parallel-connected inverters. Thus, the HC implements inner, primary, and secondary control. The first, inner control loop, regulates the inverter output voltage using the stationary reference frame. On one hand, the primary control implements the universal droop control, which is in charge of active and reactive power share between inverters. On the other hand, the secondary control restores the voltage and frequency deviations because of the primary control. Finally, the results validate the advantages strategy in power inverters. The proposed control scheme effectiveness has an excellent performance, as it applied in micro-grids in the event of abrupt changes or parameter variations
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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