1,721,178 research outputs found
Modelli e simulazione per l'analisi delle interferenze elettromagnetiche condotte ed indotte
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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
Flux-Weakening in IPM Motor Drives: Comparison of State-of-Art Algorithms and a Novel Proposal for Controller Design
No full textA review and comparison of some state-of-the-art flux-weakening algorithms for Interior Permanent Magnet Synchronous Motor (IPMSM) is presented in this paper, having voltage exploitation, dynamical performances and implementation efforts as key parameters of the comparison. Moreover an original proposal for the theoretical analysis of the overall dynamics of the voltage control loop is carried out, also taking into account non-linear effects and discrete-time implementation issues. All the considered algorithms have at least one feed-back path, thus providing steady-state voltage control even in presence of parameter errors, but different strategies are adopted leading to completely different behavioral characteristics. The approaches that will be analyzed are based on the control of the synchronous reference frame currents, the torque-flux characteristics and the voltage space vector angle. The effort for improving the voltage limitation performances, aiming at increasing dc bus voltage exploitation while still maintaining reasonable dynamical performances, is gaining importance due to both the efficiency demand (i.e. reducing the phase current magnitude for the required power) and some specific application issues, like the need for widening the speed-torque range given a relatively low voltage bus (e.g. in electrical or hybrid traction applications). A motor drive system for home appliances is considered in this paper as test bench for comparing the reviewed techniques. Simulation and experimental results are included
Prediction of Overload and Flux-Weakening Performance of a IPM Motor Drive: Analytical and Finite Element Approach
No full textThe performance of an Interior Permanent Magnet (IPM) synchronous motor are predicted at base speed and in the flux-weakening speed range, given the geometrical and physical data of the motor. Both the continuous and the intermittent (overload) operating regions are considered. Two different approaches are proposed: (i) by an analytical model in which the non-linearity due to the iron saturation is implemented in a simple way. The parameters of the analytical model are calibrated by the results of few Finite Element analyses; (ii) by a complete Finite Element analysis carried out in all the operating point of interest. Accuracy of the methods is verified by comparing the results with experimental measurements. Merits and disadvantages are also 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
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