1,720,973 research outputs found
ANALYSIS OF THE PROPAGATION OF DISTORTION IN THE FREQUENCY RANGE 2-150 KHZ USING ITERATIVE HARMONIC ANALYSIS
No full textThis paper presents an extension of the iterative harmonic analysis (IHA) method to assess the propagation of conducted disturbances up to 150 kHz in multi-device systems. This includes a review of IHA and the implications and challenges associated with obtaining accurate network solutions in the 2-150 kHz frequency range. Numerical simulations confirm the applicability of the IHA method to cases of practical interest
Comparison of frequency domain models for assessing the harmonic emissions of low voltage photovoltaic systems
No full textThe proliferation of photovoltaic (PV) systems connected to low voltage (LV) distribution networks can have detrimental impacts on waveform distortion. This is caused by the power electronic interface, with voltage source converter (VSC) technology being by far the most prevalent. As such, proper emission models, which can account for the non-linear operation of VSCs used in PV systems have to be developed and investigated for the assessment of harmonic distortion in LV networks. This paper compares different frequency domain models (FDMs), specifically, methods based on frequency coupling matrices and an analytical method based on a harmonically coupled impedance matrix, for the type of single-phase PV systems typically found in LV distribution networks. Two case studies are presented to compare the models in terms of computational complexity and accuracy, with results showing that models accounting for the interaction between same order harmonics are sufficiently accurate
Emission assessment of single-phase switch-mode PFC loads up to 150 kHz: Experimental analysis and modelling
No full text
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
Comparison of Frequency Domain Modelling Techniques for Assessing the Harmonic Emissions of Low Voltage Photovoltaic Plants
No full textIn modern power systems voltage source converters (VSCs) are often used for interfacing renewable distributed generation units. To evaluate the impact on power quality of the widespread use of VSCs proper models and methods have to be developed and investigated. In this paper, a review of harmonic models in the frequency domain is carried out and Norton-based models are applied and compared in terms of computational complexity and accuracy. For this purpose, a 12 kW photovoltaic plant (of the type typically found in low voltage distribution networks) is analysed for a range of operating conditions
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