1,721,206 research outputs found
A NOVEL SLITTED TOOTH CORE DESIGN to DECREASE LEAKAGE FLUX in INDUCTION MOTOR
No full textInduction motors, due to the extensive use in industrial applications, are dominant factor in terms of energy consumption in many countries. Especially in recent years, many studies have been realized to achieve higher energy savings in induction motors. Thus, even if a small percentage increases in efficiency would result in a huge amount of energy savings in a global scale. In this work, a new design for the core is proposed to increase the induction motor performance. In the proposed design, slits are inserted between the stator and the rotor teeth. In the slitted models proposed, the slit depth and width are optimized using Finite Element Method in F.E.M.M. (Finite Element Method Magnetics) software. Saturation points, variation of flux leakage and zigzag flux obtained from both proposed and original motor are given in comparison
EFFICIENCY IMPROVEMENT IN INDUCTION MOTOR BY SLITTED TOOTH CORE DESIGN
No full textIn this study, a new design was suggested in order to improve the performance of induction motors. In the proposed design, slits were applied in the middle of stator and rotor teeth. In these slitted models, the depth and width of slits were optimized with Finite Element Method Magnetics (FEMM) software using Finite Elements Method (FEM). To show performance improvement, suggested motor model and a reference motor model were compared at the rated operating point for the values such as input and output power, input current, power factor, efficiency and losses. Because of the decreases in both iron and copper losses, total losses in motor were reduced and the efficiency for rated operating point was improved by 1,869%. In the modelling, 3 kW squirrel-cage induction motor was used
EFFICIENCY OPTIMIZATION OF SLITTED-CORE INDUCTION MOTOR
No full textIn this study, a 3kW squired cage induction motor having slits in stator and rotor were examined . The slite depth and width in the 56 different sated motor models were optimized with Finite Element Method Magnetics (FEMM) software by using Finite Elements Method (FEM). What value the depth and width of optimum slit should be was determined in order to obtain maximum motor efficiency in the new motor models created with the proposed slitted structure, and how the depth and width of slit could affect the performance of motor was demonstrated
Induction motor parameter estimation using metaheuristic methods
No full textThe steady-state equivalent circuit parameters of an induction motor can be estimated using the operation characteristics that are provided by manufacturers. The characteristics of the motor used in estimation methods are the starting, maximum, and nominal torque values; the power factor; and efficiency. The operation characteristics of a motor given in data sheets are generally based on design parameters and are not suitable with real values. For this reason, in this paper, the data used in the parameter estimation for induction motors are taken from the literature. Using an optimization method for parameter estimation is useful for comparing the manufacturer values and values at the end of estimation, as well as minimizing the error in between. There are many methods in the literature for the parameter estimation of induction motors. In this study, the estimation is made using the charged system search (CSS), differential evolution algorithm (DEA), particle swarm optimization, and genetic algorithm optimization techniques. The CSS algorithm is first applied for estimation of the parameters of an induction motor. The results obtained from all of the methods show that the CSS algorithm is suitable with the DEA. From the obtained results, it is understood that an exact approach can be made to equivalent circuit parameters in case the values given by the manufacturer model the motor properly
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
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