1,720,952 research outputs found
AC Loss Modeling of Superconducting Field Windings for a 10MW Wind Turbine Generator - an Analytical and Numerical Analysis
No full textThe total installed capacity of wind turbines is growing as society moves towards a more sustainable energy supply. With the integration of more wind turbines in the grid the price and reliability of future wind turbines are very important. One of the promising drive train topologies currently investigated is the direct drive superconducting wind turbine. This configuration allows for higher reliability, less top mass and nearly full independence of the volatile market of rare earth metals. However, the superconducting windings in such a generator operate only at cryogenic temperatures which is a challenge in the design of the machine. Since superconducting windings operate at a very low temperature it is important to estimate the heat generation in the windings. AC loss is the main cause of heat generation in a superconducting field winding. This thesis attempts to analyse the AC loss in two 10MW superconducting generator designs using analytical and numerical modeling. After introducing the problem description, the theory concerning AC loss in superconducting wires is treated. Then, the methods for both modeling techniques are established and partly validated. The results are then shown and discussed after which the conclusions are drawn. Both generators are designed for the same turbine and therefore have the same rotational speed and rated power which makes them comparable. The geometry however is different and as the results will show, these differences in design result in major differences in AC loss. Depending on machine geometry the analytically calculated AC loss is ranging from 22.2W to 283W in the Non Magnetic Teeth (NMT) design and 0.7kW to 2.9kW in the Iron Teeth (IT) design. The numerically calculated hysteresis loss is on average 154W in the NMT machine and 371W in the IT machine.Sustainable Energy TechnologyElectrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc
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
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
Homogeneous superconducting phase in TiN film: A complex impedance study
Get PDFThe low frequency complex impedance of a high resistivity 92?????cm and 100?nm thick TiN superconducting film has been measured via the transmission of several high sensitivity GHz microresonators, down to TC/50. The temperature dependence of the kinetic inductance follows closely BCS local electrodynamics, with one well defined superconducting gap. This evidences the recovery of a homogeneous superconducting phase in TiN far from the disorder and composition driven transitions. Additionally, we observe a linearity between resonator quality factor and frequency temperature changes, which can be described by a two fluid model.Delft Institute of Microsystems and NanoelectronicsElectrical Engineering, Mathematics and Computer Scienc
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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