1,720,958 research outputs found
Smart real-time scheduling of generating units in an electricity market considering environmental aspects and physical constraints of generators
No full textOptimal scheduling of generating resources plays a significant role as a decision-making tool for power system operators in the liberalized and real-time electricity spot markets. The real-time scheduling of generating units will become a very complex task with respect to the instantaneous fluctuation of the load demand due to several demand response scenarios in the smart grid context. In this study, a hybrid mathematical method for the online scheduling of units based on the least square support vector machine (LSSVM) and the third version of cultural algorithm (CA3) has been presented, where the CA3 has been specifically employed to tune the adjusting parameters of LSSVM. For the training purpose of the proposed method, the optimal scheduling of the daily load curve for four different test systems and various physical and environmental constraints of generating units have been prepared by using a modified mixed integer quadratic programming (MIQP) to deal with non-convex behaviors of the test systems. A mean squared error (MSE) objective function has been used to reduce the prediction errors during the training process to enhance the precision and reliability of the results. A radial basis function (RBF) and the proposed LSSVM-CA3 were used to check the convergence process. A high accuracy of generator schedule predictions are demonstrated by comparing the results of the proposed method with those of artificial neural networks. From the results, it can be inferred that the method is highly compatible for real-time dispatching of generation resources in deregulated electricity markets
Discrimination between nearby and direct lightning strikes to a long operational medium voltage line to assist in the determination of the basic insulation level (BIL)
No full textA thesis submitted in partial fulfilment of the requirements for the degree Doctor of Philosophy to the Faculty of Engineering and the Built Environment, School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, 2022The lightning performance of a Medium Voltage (MV) line needs to be divided into two categories: lightning performance due to nearby lightning and direct lightning strikes. A better nearby lightning performance requires a higher Basic Insulation Level (BIL) while the direct lightning performance requires a lower BIL to minimize equipment failure. The electromagnetic coupling models for calculating the Lightning Induced Overvoltage (LIOV) on a line are complicated and reliant on accurate input data. Therefore, short floating lines (< 3 km) were used to calculate the line’s lightning performance. The models were then verified with LIOV measurements on these short floating lines and the results were normalized to estimate the lightning performance of long operational lines. These estimations for long lines could never be verified due to the complexity of calculations and the cost and logistics of equipment to do measurements on long operational lines. A new methodology to measure the lightning performance of a long operational line was developed and verified. The obstacles such as the long line length, the changing soil resistivity, the lightning channel properties and the rapid attenuation of the LIOV along the energized line have been used as an advantage in the new method. The finite soil conductivity was used as an advantage to distinguish between nearby lightning and direct lightning strikes while the power frequency current was used to determine whether the LIOV exceeded the line BIL and caused a line fault. An existing electromagnetic coupling computer model, the ATP-EMTP, was verified with the existing ERM using the same input data. The ATP-EMTP model was then extended to include the equipped long MV line. There was no existing model or measurements to which the results could be compared to. Actual nearby lightning and direct lightning strikes of which the termination point was known were used to verify the new methodology. A significant size database (consisting of 38 675 lightning flashes and 1 155 line faults over two years) was used to evaluate the IEEE Std 1410-2010 estimated lightning performance of the long line.ESKOM Power Plant Engineering Institute (EPPEI)-HVACTL (2024
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
Smart real-time scheduling of generation units in an electricity market considering environmental aspects and physical constraints of generators.
Full text linkDoctor of Philosophy in Electrical Engineering. University of KwaZulu-Natal, Durban 2017.Abstract available in PDF file
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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