1,721,110 research outputs found
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
Proposals and Analysis of Space Vector-Based Phase-Locked-Loop Techniques for Synchrophasor, Frequency, and ROCOF Measurements
Full text linkSpace vector (SV)-based estimation algorithms represent attractive methods for synchronized phasor, frequency, and rate of change of frequency measurements in three-phase ac power systems. Recently, a phase-locked-loop (PLL) solution for improving the demodulation of the SV signal has been proposed. In this article, the potentialities of the SV-PLL approach are investigated in order to optimize accuracy and computational load. First, the impact of the PLL update rate on achieved performance is analyzed. Then, a novel two-step SV-PLL algorithm is presented so that the accuracy of a fast PLL execution frequency can be matched with a considerably lower computational cost. The behavior in the case of fast phase angle variations has been also significantly improved. The proposed synchrophasor estimation technique has been validated through simulations; exemplary dynamic performance suggests that it is particularly suitable for grid control applications. Experimental tests carried out on a real-time implementation confirm simulation results
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
Characterization of Inductance Gradient and Current Distribution in Electromagnetic Launchers
No full textWe reapproach the characterization of the inductance gradient and the current distribution in electromagnetic rail launchers with multiple brush armatures. A measurement procedure based on the use of a loop system mutually coupled with the launcher is illustrated for the case of a two-brush armature. We show how to estimate the current distribution between the brushes following the basic rules of the partial-inductancemethod. To test the proposed procedure, we performed an experimental analysis on a rail launcher prototype supplied by a high-voltage high-power capacitor bank. Experimental results were obtained under the static condition of the armature, and they are in agreement with theoretical calculations
CARATTERIZZAZIONE DI ALTE CORRENTI IMPULSIVE E LORO DISTRIBUZIONE IN ARMATURE MULTISPAZZOLA
No full textIn questo articolo viene descritto un metodo per la misura della corrente in un lanciatore elettromagnetico (railgun) e della sua distribuzione tra le spazzole di un'armatura solida. Dalla misura del flusso concatenato è possibile ricavare le correnti nelle spazzole. Per la misura della corrente totale viene descritto un prototip di shunt realizzato presso i laboratori dell'Unità di Pisa. Le tecniche di misura descritte sono state sviluppate sulla base del metodo delle induttanze parziali
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