1,720,956 research outputs found
Enhanced Control and Power Management for a Renewable Energy-Based Water Pumping System
Get PDFThe paper introduces a comprehensive dynamic analysis for a renewable energy based water pumping system. The complete system components are described in details. The components include a wind turbine power system, a permanent magnet synchronous generator (PMSG), a water pumping system and a battery. The storage system is used to enhance the power delivery under weak wind production which consequently enhances the system reliability. Considering the PMSG as the fundamental power unit in the system, a new predictive control procedure is presented to enhance the PMSG performance. To validate the effectiveness of the proposed control scheme, a detailed comparison is accomplished between the designed controller and other three traditional controllers to evaluate the most effective in between. A power management scheme is constructed to manage the power flow and ensuring a sufficient power delivery to the pumping system. The obtained results are presented and analyzed in details to compare between the dynamics of the four predictive controllers used to manage the generator operation. The results report that the formulated control scheme has the best performance in terms of the reduced fluctuations, low calculation capacity, structure simplicity and low currents THD. The obtained results also approve the validness of the designed power management strategy in balancing the power flow and stabilizing the DC bus voltage as well
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
Optimisation multicritère du dimensionnement d’un micro- réseau électrique urbain à base des énergies renouvelables
Get PDFRésumé
Les micro-réseaux autonomes deviennent des alternatives populaires dans les régions éloignées et insulaires où la connexion au réseau n’est pas économiquement ou techniquement viable. Pour cette raison, l’exploitation de l’offre abondante d’énergie renouvelable peut jouer un rôle important pour assurer une production d’énergie propre et respectueuse de l’environnement pour les communautés éloignées. Le présent travail porte sur l’intégration des micro-réseaux isolés qui présentent des petits réseaux électriques destinés à alimenter des zones rurales n’ayant pas de raccordement possible au réseau conventionnel principal. Ces micro-réseaux fonctionnant à base de production éolienne, de groupes électrogènes et de système du stockage par batteries, sont plus fragiles et la production d’électricité peut subir des interruptions fréquentes si le réseau n’est pas conçu avec précaution. La fiabilité est donc un critère préliminaire pour assurer d’une part la viabilité de ces projets et d’autre part pour permettre l’amélioration des conditions de vie des communautés. Pour cette raison, une méthode de conception multi-objective de ces micro-réseaux basée sur des critères technoéconomiques est proposée. Un algorithme itératif est développé pour faire évoluer la configuration du micro-réseau vers un optimum et permet de visualiser les compromis entre les critères fixés. Ce dernier est comparé à un algorithme intelligent évolutif qui a permis d’optimiser d’avantage la performance du micro-réseau. Les résultats des simulations et les tests valident notre conception du micro-réseau.
Abstract
Stand-alone microgrids are becoming popular alternatives in remote and island regions where grid connection is not economically or technically viable. For this reason, harnessing the abundant supply of renewable energy can play an important role in ensuring clean, environmentally-friendly power generation for remote communities. The present work focuses on the integration of isolated microgrids, which present small-scale power grids designed to supply rural areas with no possible connection to the main conventional grid. These microgrids, based on wind generation, generators and battery storage, are more fragile and the electricity production can suffer frequent interruptions if the grid is not carefully designed. Therefore, to overcome the intermittent and fuctuating characteristics of wind power, reliability is a preliminary criterion to ensure the viability of these projects on the one hand, and to enable the improvement of communities’ living conditions on the other. For this reason, a multi-objective design method for these microgrids based on techno-economic criteria is proposed. An iterative algorithm is developed to evolve the microgrid confguration towards an optimum and to visualize the trade-offs between the set criteria, compared with an evolutionary intelligent algorithm that further optimized microgrid performance. Simulation results and tests validate our microgrid design
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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