1,720,968 research outputs found
The Effect of Humidity on the AC Breakdown Strength of C4-FN/CO2 (5%/95%) and the Partial Discharge Behavior of Corona Under Different Operating Conditions
No full text[EN] SF6 is being phased out of the electrical grid as it is a strong greenhouse gas. A "green" alternative to SF6 is fluoronitrile (C-4-FN). The dutch transmission system operator (TSO) TenneT wanted to investigate the electrical behavior of this "green" alternative as a pilot-gas insulated line (GIL) filled with C-4-FN/CO2 (5%/95%) experienced multiple electrical breakdowns during the site acceptance tests (SATs). TenneT hypothesized that the breakdown was caused by the effect of (too much) humidity in the gas. Therefore, the ac breakdown behavior of the gas mixture has been researched under different amounts of humidity and operating pressures. This article also makes a small introduction on how humidity affects partial discharge (PD) behavior of corona, which is often a breakdown indicator. The results of this research conclude that humidity affects the ac breakdown strength. An increase in humidity in the gas results in a decrease in the ac breakdown strength. Moreover, the field configuration determines the amplitude of the impact. The impact of humidity on the ac breakdown strength in a homogenous field is substantially more compared to an inhomogeneous field, where the impact can almost be ignored. Yet, the effect of humidity decreases as the operating pressure increases. The phase-resolved PD pattern and PD characteristics of corona in a C-4-FN gas mixture also differ with humidity. On the other hand, the PD inception voltage did not change with the humidity content. As a result of the findings in this research, further research is proposed toward the affected breakdown mechanism and more various PD behavior.Veldhuizen, E.;Mier Escurra, C.;Lathouwers, A.;Rodrigo Mor, Armando;Ghaffarian, M. (2024). The Effect of Humidity on the AC Breakdown Strength of C4-FN/CO2 (5%/95%) and the Partial Discharge Behavior of Corona Under Different Operating Conditions. IEEE Transactions on Dielectrics and Electrical Insulation. 31(5):2503-2510. https://doi.org/10.1109/TDEI.2024.3390649S2503251031
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
Nueva metodología de la medida de descargas parciales en cables de alta tensión. Desarrollo de un sensor capacitivo de gran ancho de banda
Get PDFEn la actualidad la medida de descargas parciales constituye una herramiento eficaz para el diagnóstico de fallos de aislamiento. La presente tesis está centrada en los diferentes métodos de ensayo de descargas parciales en cables de media y alta tensión. Principalmente se ha estudiado la influencia de los diferentes métodos de ensayo en la evaluación de la carga de los pulsos de descargas parciales en ensayos off-line (ensayos en lso que se saca el cable fuera de servicio).
La tesis analiza las particularidades de los métodos convencionales, y de los nuevos métodos o métodos no convencionales.
Los métodos convencionales, empleados desde los años 60 en laboratorios de alta tensión, emplean filtros paso-banda como herramienta para la evaluación de los pulsos de descargas parciales.
Los métodos no convencionales emplean sensores con anchos de banda muy superiores a los métodos convencionales pues esto permite la localización de los pulsos por técnicas de reflectometría y el uso de herramientas matemáticas que ayudan a la identificación de los pulsos de descargas parciales.
En esta tesis se proponen y comparan diferentes métodos de evaluación de carga para los métodos no convencionales, y se establecen los límites de la incertidumbre en dichas medidas en función del ancho de banda de los sensores y de la longitud de los pulsos de descargas parciales.
La tesis aborda el análisis de los transformadores de corriente de alta frecuencia que comúnmente se emplean como sensores de descargas parciales para medidas acopladas por campo magnético, y el estudio de los sensores acoplados por campo eléctrico. La comparativa de ambos sensores permite extraer conclusiones acerca de los anchos de banda obtenidos, de la incertidumbre alcanzada para diferentes longitudes de pulso y métodos de evaluación de carga, y de la sensibilidad de los sistemas de medida que emplean estos sensores.
Las medidas experimentales se han realizado empleando diferentes prototipos de sensores acoplados porRodrigo Mor, A. (2012). Nueva metodología de la medida de descargas parciales en cables de alta tensión. Desarrollo de un sensor capacitivo de gran ancho de banda [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16271Palanci
Medida de descargas parciales en aisladores poliméricos
No full textProyecto ConfidencialRodrigo Mor, A. (2007). Medida de descargas parciales en aisladores poliméricos. https://riunet.upv.es/handle/10251/36494.Archivo delegad
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
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