1,720,968 research outputs found
Insights into Methods for Electric Machine Winding Design
Full text linkThe design of the stator winding has direct influence on the electric machine performance. As technology has advanced, researchers and motor manufacturers have worked on possible ways to improve the stator winding layout to achieve several targets depending on the application which namely consist of minimization of harmonic losses for improved efficiency, torque pulsation reduction, acoustic noise and vibration reduction,... For this purpose, an extensive range of literature have presented several design strategies for both synchronous and induction motors acting on winding connection types, configurations, conductors type and shape..., to achieve the required electrical performance. It has been shown that - depending on the application - some winding configurations can be more problematic than others as they produce additional undesirable parasitic effects. However, in some cases, the choice of the winding layout is limited by the required application which leads to look for solutions to cope with the winding configuration drawbacks.
The works presented in this thesis will deal with two different aspects of electrical machine windings that need to be further explored which consist of: fractional slot concentrated winding optimization in three-permanent magnet machines and study and improvement of the winding in terms of skin effect is large-medium voltage synchronous machines. Regarding the first topic, potentials and limits of the FSCW optimization through multi-layer arrangement will be presented to mitigate three problems: unbalanced magnetic pull (UMP), torque ripple and permanent-magnet eddy-current losses. As for the second topic, an extensive study of the eddy-currents losses in the stator equipped with form wound coils made of flat conductors embedded in open slots will be covered. Such study is important as it helps to identify the main causes of problems to avoid it through a suitable design.The design of the stator winding has direct influence on the electric machine performance. As technology has advanced, researchers and motor manufacturers have worked on possible ways to improve the stator winding layout to achieve several targets depending on the application which namely consist of minimization of harmonic losses for improved efficiency, torque pulsation reduction, acoustic noise and vibration reduction,... For this purpose, an extensive range of literature have presented several design strategies for both synchronous and induction motors acting on winding connection types, configurations, conductors type and shape..., to achieve the required electrical performance. It has been shown that - depending on the application - some winding configurations can be more problematic than others as they produce additional undesirable parasitic effects. However, in some cases, the choice of the winding layout is limited by the required application which leads to look for solutions to cope with the winding configuration drawbacks.
The works presented in this thesis will deal with two different aspects of electrical machine windings that need to be further explored which consist of: fractional slot concentrated winding optimization in three-permanent magnet machines and study and improvement of the winding in terms of skin effect is large-medium voltage synchronous machines. Regarding the first topic, potentials and limits of the FSCW optimization through multi-layer arrangement will be presented to mitigate three problems: unbalanced magnetic pull (UMP), torque ripple and permanent-magnet eddy-current losses. As for the second topic, an extensive study of the eddy-currents losses in the stator equipped with form wound coils made of flat conductors embedded in open slots will be covered. Such study is important as it helps to identify the main causes of problems to avoid it through a suitable design
MEC-based prediction of the air gap flux density distribution of spoke-Type IPM machines
No full textThe paper is aimed at an analytical prediction of the air gap flux density distribution of a spoke type interior permanent magnet machine, based on its magnetic equivalent circuit (MEC) incorporating the rotor position. The study is initiated by an elaboration of the machine MEC in two particular rotor positions corresponding to the maximum and null magnetic coupling between the stator and rotor which enable the prediction of the direct and quadrature components of the air gap flux density, respectively. The decomposition of the armature magnetic reaction into direct and quadrature components enables the generalization of the prediction of the air gap flux density waveform for any rotor position. The accuracy of the proposed approach is improved taking into account the stator and rotor slotting effects that are analytically incorporated considering complex permeance functions
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
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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