1,720,958 research outputs found
A Feasibility Study for Agriculture Tractors Electrification: Duty Cycles Simulation and Consumption Comparison
No full textOn the efficiency requirements for electrical motors and power electronics in complete drive systems
No full textThis paper focuses on efficiency levels for low power electric drive. In particular a domestic drive with a power of 1.1 kW is considered. After a general review of the applicable standards, the different specification on the efficiency levels is presented. In particular, the perspective of a motor manufacturer is adopted in order to understand which is the proper efficiency level of the motor in order to fulfil the efficiency requirements of the complete drive system
Design of electric motors and power drive systems according to efficiency standards
Full text linkThe focus of this article is the design of high efficiency electric motors adopted in power drive systems (PDS). The last efficiency standards are considered as constraint for the motor and drive design: they are introduced and described and their impact on the choice made during the design process are highlighted. As a particular case, the perspective of a motor manufacturer is adopted in order to understand which is the proper efficiency level of the motor required to fulfil the efficiency requirements of the PDS. This is not always clear and easy to understand because different standards apply in the two contexts. A design example of an industrial motor with 3 kW power is included, showing also experimental results on a prototypes. Also the standards related to the experimental tests, in particular those prescribing instrument accuracy, are considered and commented in the article
Optimization of a Line-Start Motor for Centrifugal Loads within Premium Efficiency According to IEC Standard
No full textLine-start motors are gaining more attention in recent years as they can achieve very high efficiency while retaining the ability to self-start when connected directly to the grid. However, motor design is not a trivial matter, particularly when a certain compromise has to be found between performance at steady-state and the ability to synchronise even with large inertial loads. In this study the design of a line-start motor for centrifugal loads is presented, with particular attention to the rotor geometry, adopting a multi-objective optimisation including finite element analysis. Thanks to a proper selection of the objective function, both efficiency at steady state and starting capability are included in the optimization process
Energy Management of a Dual-Motor Electric Vehicle Based on Particle Swarm Optimization
No full textThis paper was conceived in response to the IEEE VTS Motor Vehicle Challenge 2021, where the development of an Energy Management Strategy (EMS) for a dual-motor all-wheel drive electric vehicle was required. An EMS based on an adaptive non-linear particle swarm optimization was implemented for both traction and braking force distribution. Simulation results and comparisons are commented in the end
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
Measurements and simulation of induction machines flux linkage characteristics adopting rotor field orientation
No full textThe focus of this work is on the finite-element prediction and experimental measurement of stator and rotor flux linkages for induction machines. The purpose is to characterize the stator and rotor flux linkages adopting a rotor field oriented reference frame. The proper basic set of equations is inspired from the direct field oriented control approach, in order to indirectly derive the rotor flux linkage from the measurement of the stator flux. The proposed method requires a small set of preliminarily known parameters, such as the stator resistance and the overall leakage inductance. Moreover, the only measured quantities are voltages and currents, from which the fluxes are derived. The adopted strategy offers also the possibility to estimate electromagnetic torque and rotor resistance, using the rotor field oriented model equations. A complete finite-element validation is reported for comparison
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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