1,720,986 research outputs found
A calibration procedure for a digital instrument for electric power quality measurement
No full textThe measurement of power quality is becoming an impelling need in a deregulated electricity market where the
sources producing distortion and disturbances are steadily increasing
in number and power. The instruments for power quality measurement are based on complex digital processing of the input signals, whose waveforms are highly variable. The calibration of
this kind of instruments is therefore an open topic, especially when the uncertainty propagation through the digital signal processing (DSP) algorithm is concerned. This paper proposes an innovative procedure, based on the Monte Carlo method. Starting from the determination of the probability density function of the uncertainty contribution of every device from the signal input stage to
the analog-to-digital conversion stage, this procedure estimates the probability density function of the measurement results and the measurement standard uncertainty as the standard deviation associated with this function. The result of the experimental work done on a prototype of a power quality measurement instrument is reported
An Experimental Comparison in the Uncertainty Estimation affecting wavelet-based Signal Analysis by means of the IEC-ISO Guide and the Random-Fuzzy Approaches
No full textThe aim of this paper is the comparative estimation of the measurement uncertainty associated to the results of complex measurements, such as the evaluation of the wavelet transform of signals affected by transient disturbances. The uncertainty estimation is performed by means of two different methods: the approach suggested by the IEC-ISO “Guide to the Expression of Uncertainty in Measurement" and the one, recently proposed in the literature, based on the use of Random-Fuzzy variables. The comparison is performed starting from actual signals generated and acquired by means of a suitable test system
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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