1,720,971 research outputs found
Analytical formulation for design and optimization of permanent magnet arrays
No full textRare earth permanent magnet arrays are extensively used in many electromagnetic devices. Their
preliminary design can be eased by the analytical approach presented in this paper. It allows a fast evaluation of the flux density distribution and of the winding flux linkage and induced emf as functions of the configuration parameters and therefore can be particularly profitable to optimise the electromagnetic configuration
Automated Procedure for the Performance Improvement of a Low-power Single-phase Synchronous Motor
No full textThe performance of a low power line-start single-phase synchronous motor is evaluated via a mathematical model, elaborating the results of an automated sequence of magnetostatic FEM analyses. Such an approach remarkably speeds up the transient simulation with respect to a commercial FEM code for the transient analysis, allowing analysis of the influence of the parametric variations in a reasonable lapse of time. An optimization procedure based on such a technique could be profitably applied to a self-starting single-phase synchronous motor
A magnetic network approach to the transient analysis of synchronous machines
No full textThe technique for the simulation of the dynamic behaviour of rotating machines presented in the paper is based on an equivalent circuit representation of the magnetic configuration. The circuit parameters are obtained by a preliminary automated sequence of magnetostatic FEM analyses and take into account the local magnetic saturations. The adopted solution technique is based on an invariant network topology approach: its application, presented for the operation analysis of a low-power synchronous generator, allows a great reduction of the calculation time in comparison with a commercial FEM code for the transient simulation
Design Aspects of Coils for EDS Levitation Systems
No full textEDS systems based on high frequency supplied windings are convenient candidates in standstill and low motion applications where strict mechanical tolerances are not practicable. In this paper a simple EDS system, based on a single levitation coil, is analyzed by an implementation of analytical formulations of the levitation force and of the vertical levitation stiffness. Such methodology can be effective for the parametric analysis to investigate the influence of the geometric sizes and to optimize the system performance taking into account the design constraints
A linear actuator supplied by inductive coupling in a moving coil transformer configuration
No full textMany applications require a high-dynamic short stroke linear actuator with a low mover inertia; at the same time the mechanical reliability represents a crucial factor for high frequency operation cycles. Under such circumstances, the supply feeding cables and the related cable tray may represent a weak point and a considerable load increase at the same time. The device presented in this paper doesn’t require any cable supply, since the power required by the moving windings is transferred via the electromagnetic coupling with a stator AC supplied primary winding
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
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