1,721,177 research outputs found
Safe transition from connection mode to islanding mode in Microgrids
No full textThe lack of spinning reserves makes MGs unable to rapidly follow load changes resulting in unbalancing between generation and consumption which in turn causes voltage and frequency deviation from permitted ranges and even to instability. The current paper addresses this stability problem by presenting a novel control system for power converter-based low voltage MGs stabilization. The converter mode operation technique is adopted to improve the operation of MGs in both connecting and islanding modes and also to achieve safe transient between these two modes. The droop control concept is adapted to improve the cooperation between power converters in order to optimally regulate voltage and dispatch the load demand. A battery is used to provide the fast response to load changes and also to compensate unbalancing between load demands and power generation in IM. In addition, a fuzzy based control system is employed to improve the robustness of the control system by adjusting the gains of control loops
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Simultaneous reactive power sharing and voltage regulation in an autonomous networked microgrid
Get PDFDecentralised droop-like control method is the most favourable control system for power converter-based microgrids (MGs). In conventional V–Q droop loops, reactive power sharing is used as a means of voltage regulation to prevent currents from circulating among distributed generation units. However, since the voltage is not a global variable, reactive power sharing is not implemented precisely, and thus converters may be exposed to overcurrent conditions and the stability of the MGs is put at risk. Besides, the droop-like reactive power sharing causes voltage deviations and power quality issues. This study proposes a novel control method which is able to implement accurate reactive power sharing and voltage regulation to its nominal band in a networked MG. Both the control targets are achieved, fast and simultaneously, by only one control signal. So the requirement of a secondary controller for voltage restoration is obviated. A novel power flow-based method is proposed to estimate the voltage at the MG main bus, which is adopted as a common variable, thus making the proposed method decentralised. The presented method is fast, effective and applicable to networked MGs with arbitrary topology. Simulation results prove the effectiveness and superiority of the proposed method over existing methods
Open data portals as part of the open data ecosystem?: Lessons learned from geoportal research
No full textMany countries and also cities have their own open data portal, which provide geographic data that can be used even by citizens. One of the current challenges is to satisfy user needs to ensure that the data that is provided through the portal isactually used. This paper provides insights in the findability of datasets through of a special kind of portal: the geoportal. It presents the main findings of research accomplished on the findability, attainability and usability of geoportals through anassessment of the transaction costs involved.OLD Geo-information and Land Developmen
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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