1,720,954 research outputs found
Temperature gradient effect on the space charge behaviour in multilayers of oil and pressboard
No full textThe presence of space charge within oil and pressboard (PB) can lead to distortion of electric field within converter transformers. Electric field distortion can cause materials to be overstressed which accelerates degradation, and can result in breakdown. Therefore, it is important to analyse the factors that affect space charge formation and dissipation such as temperature, moisture, ageing, multilayers and electric fields. This paper focuses on the temperature gradient and multilayers of oil and PB on space charge. Considering the inhomogeneous acoustic wave velocity caused by a temperature gradient and different dielectric properties of multilayers of materials, an improved space charge recovery algorithm has been developed, in which the distortion of the acoustic wave caused by the attenuation, dispersion, different dielectric properties and temperature effects have been considered. It has been found that for two layers consisting of PB and oil with the bottom electrode fixed at 20 ᵒC, the electric field in the oil increases under the temperature gradient while decreases at ambient temperature. For a three layered sample consisting of PB, oil, and PB with the bottom electrode at ambient temperature, the electric field gradient exists under the temperature gradient and the maximum electric field occurs near the cathode while occurs near the anode at ambient temperature
Study of DC breakdown in multilayered insulation systems
No full textMultilayer insulation systems have been widely used in both high voltage alternating current (HVAC) and high voltage direct current (HVDC) power systems. A well designed multilayer insulation structure could benefit the performances and reliability of the overall insulation system and as well as costs reduction. In this present work, DC breakdown strengths of various combinations of multilayer polyethylene terephthalate (PET) films (from one to four layers) with a same total thickness were investigated. It has been found that multilayer symmetrical structures can enhance the breakdown strength of the insulation system. Space charge characteristics of these various configurations have been initially studied, in order to understand the results of the DC breakdown tests. The space charge results indicate that large amount of fast moving charges presences immediately after the voltage application, which can be partially blocked and trapped by the interfaces between film layers. The trapped charges could further distort the electric field distributions in the insulation system, and resulting field enhancement in thin layers, particularly in unsymmetrical configurations. However, more evidences and investigations are required for better understanding the mechanisms of breakdown in multilayer insulation system.</p
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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