1,720,959 research outputs found
Sparkover and breakdown mechanism in HV insulating materials
No full textUvedená bakalářská práce se zabývá problematikou vzniku přeskoku a průrazu v izolačních materiálech a poskytuje stručný náhled do izolačních materiálů aktuálně využívaných či zkoumaných s cílem řešit náhradu materiálů ohrožujících životní prostředí. Ve třech hlavních kapitolách popisuje proces přeskoku či průrazu v plynném, kapalném a pevném izolačním médiu s uvedením příkladů nejvýznamnějších materiálů a charakteristikou jejich vlastností.ObhájenoThis thesis goes over the issue of the breakdown mechanism in insulation materials, and provides a brief overview of the currently used insulation materials and materials that are subjected that is researched in order to solve the problem of the replacement of environmentally hazardous materials. This thesis is divided into three main chapters. It contains views into the breakdown mechanism of gaseous, liquid and solid insulating materials with an introduction to the most important materials, as well as their properties
Design and construction of a laboratory demonstrator of a superconducting phenomenon
No full textUvedená práce poskytuje v první části ucelený náhled do oblasti supravodivosti a v druhé části popisuje klíčové kroky při realizaci laboratorního demonstrátoru supravodivého jevu v podobě levitujícího vláčku. Cílem první části je seznámení s problematikou supravodivosti z pohledu fyzikálního, materiálního a technologického. Vzhledem k rozsáhlosti je kapitola o materiálech věnována pouze komerčně využívaným supravodičům. V poslední kapitole o supravodivých technologiích jsou shrnuty nejperspektivnější možnosti aplikace supravodivosti s důrazem na klady a zápory v oblasti energetiky.ObhájenoThis work provides a comprehensive overview of superconductivity in the first part, whereas the second part describes the key steps during the realization of a laboratory demonstrator of a superconducting phenomenon in the form of levitating train. The main goal of the first part is to get familiar with the issue of superconductivity from a physical, material, and technological point of view. Due to its large extent, the part dealing with materials focuses only on commercially used superconductors. The last part on superconducting technologies summarizes the most promising electric power applications of superconductivity, emphasizing advantages and disadvantages
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
The Gauss-Seidel iteration method as a tool for solving physical fields to obtain breakdown voltage for low pd values
No full textVariations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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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