1,721,058 research outputs found
The power supply system for Langmuir probes on RFX
No full textA power supply system for Langmuir probes to be used on the reversed field pinch (RFP) thermonuclear fusion experiment RFX has been developed. It is based on a full-bridge converter concept, using a pulse width modulation (PWM) technique, and is characterized by a 5 A, ±150 V rating. The power supply has been designed to ensure compatibility with the electromagnetic noise close to the machine and with the plasma, which behaves as a nonlinear rapidly varying load. The system has been optimized by numerical simulations. Tests in the laboratory and on the experiment have been performed in a wide range of working conditions, and the system has been proven to suit fairly well the RFX experimental conditions
Thyristor Making Switch System for Plasma Startup Control in RFX
No full textThe necessity of better plasma current control during the startup phase asks for a toroidal loop voltage modulation obtained with the multi step reduction of the transfer energy resistor in the OH circuit. The paper begins by discussing the characteristics of such a modulation and then describes the modifications realized and tested on the power supply and magnet systems to prove the feasibility of such an operation; finally, on the basis of the results obtained, we describe the design of the making switch system, based on a 100 mm thyristor valv
A synchronized resonant dc link converter for soft-switched PWM
No full textA resonant DC link scheme for soft-switched inverters, where the link oscillation can be synchronized with inverter modulation, is proposed. The scheme is able to operate with reduced commutation losses at a high switching frequency. Synchronization capability allows development of suitable modulation techniques that ensure improved waveform accuracy. The system performance and control strategies were verified by simulation and by experimental tests, and the interesting features of the proposed scheme were confirmed
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
Variations 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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