1,720,982 research outputs found
Analysis of integrated STATCOM-SMES based on three-phase three-level multi-pulse voltage source inverter for high power utility applications
Get PDFThis paper is aimed to investigate the operating characteristics of a static synchronous compensator (STATCOM) integrated with superconducting magnetic energy storage (SMES) for high power applications in the transmission network level. The STATCOM controller topology comprises multi-level multi-pulse neutral-point clamped-type (NPC) voltage source inverters (VSIs) using the harmonics cancellation technique, and incorporates a SMES coil. An innovative two-quadrant multi-level dcdc converter is proposed to effectively interface the STATCOM with the superconducting coil using a buck-boost topology with neutral point voltage control capabilities; thus enabling to simultaneously control both active and reactive power exchange with the high voltage power system. A detailed analysis of major system variables is presented, including analytical results and digital simulations using the MATLAB/Simulink environment. Moreover, a three-level control scheme is designed, including a full decoupled current control strategy in the dq reference frame with a novel controller to prevent the STATCOM dc bus capacitors voltage drift/imbalance and an enhanced power system frequency controller.Fil: Molina, Marcelo Gustavo. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Mercado, Pedro Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Watanabe, Edson H.. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentin
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
Control Strategy for Frequency Control in Autonomous Microgrids
Get PDFDue to the deployment of distributed generation, future grids will show reduced inertia resulting in higher dynamics and reduced frequency stability. This is especially true in microgrids (MGs). In this sense, the virtual synchronous generator (VSG) concept has been proposed as a promising solution. In this paper, the benefits of this concept are further explored studying the frequency stability improvement under simulation of different cases regarding the MG operation. Here, the analysis is carried out looking at the impact of the control parameters on the rate-of-change-of-frequency and on the average frequency deviation. The VSG concept shows a great potential to reduce both parameters improving the frequency stability.Fil: Frack Auger, Pablo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Mercado, Pedro Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Molina, Marcelo Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Watanabe, Edson H.. Universidade Federal do Rio de Janeiro; BrasilFil: de Doncker, Rik W.. Rwth Aachen University; AlemaniaFil: Stagge, Hanno. Rwth Aachen University; Alemani
Sistema patrón de medida de potencia eléctrica para baja frecuencia
Get PDFEn esta tesis se presenta un detallado estudio sobre sistemas de medida de potencia eléctrica para uso en frecuencias de red. El objetivo es la propuesta de un nuevo método que permite lograr un sistema patrón de muy alta precisión, directamente trazable a patrones de tensión continua y resistencia. El sistema se propone como parte del Patrón Primario de Potencia Eléctrica del Sistema Metrológico Nacional del Uruguay. Otros autores han propuesto sistemas que permiten una calibración directa contra patrones de continua, basados en sumadores o puentes. En estos dos principios están basados la mayor parte de los patrones primarios de los distintos países. Pero, en los casos de mayor precisión se trata de complejos sistemas, costosos y difíciles de montar y calibrar. En esta tesis se desarrolla un sistema patrón de medida de potencia basado en un medidor de factor de potencia. Hasta el momento, el factor de potencia es computado a partir de la potencia activa y la potencia aparente. En tal sentido, es una magnitud derivada. Por el contrario, se propone en esta tesis medir directamente el factor de potencia, y calcular la potencia activa a partir de él. Se propone un medidor basado en la detección de los cruces por cero de las ondas de tensión y corriente que, mediante filtros en las entradas y un adecuado procesamiento de las señales, reduce dichos errores. Con el agregado de un voltímetro y un resistor shunt (para la medida de la corriente) se completa el patrón de potencia. Adicionalmente, se presentan métodos originales para lograr alta precisión en los transductores de entrada de tensión y de corriente. Se propone un nuevo método para caracterizar el comportamiento de divisores de tensión de baja frecuencia y resistores shunts de medida de corriente basado en sus respuestas al escalón. Este método permite calcular los errores en magnitud y desfasaje en forma absoluta, sin necesidad del uso de un divisor patrón. Para transformadores de corriente y tensión se proponen circuitos electrónicos originales que reducen los errores de los mismos
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
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