1,720,996 research outputs found
Control characteristics of SRM drives. Part I: operation in the linear region
No full textThe control characteristics of switched reluctance motor (SRM) drives are analyzed for operation of the motor in the linear region of its magnetic characteristics. After reviewing the motor operation, the authors consider the current-fed and voltage SRM drives. For both types of drives, the control variables and the related ranges are identified, the relationships between such variables and the average motor torque are calculated, and the torque capability is found. The basic schemes for the speed control of the SRM drives are also formulate
Control characteristics of SRM drives. Part II: operation in the saturated region
No full textPart I of this two-part paper analyzed the control characteristics of switched reluctance motor (SRM) drives for operation of the motor in the linear region of its magnetic characteristics. This part completes the analysis, presenting the control characteristics in the saturated region. A description of the motor operation in the saturated region is first formulated. Then the control variables, the relationships between the motor torque and the control variables, and the torque capability are determined for both current-fed and voltage-fed SRM drives. The basic schemes for the speed control of a SRM are also presente
Disturbance torque estimation in a sensorless dc drive
No full textThe estimation of the disturbance torque in a sensorless DC motor drive is carried out by extending the classical observer theory. Three estimation schemes are formulated according to the representation of the disturbance torque and the processing of the observer states. In addition to the disturbance torque, all the schemes deliver an estimation of the motor speed. Steady-state accuracy and dynamics of the schemes are first determined in nominal conditions, identifying the scheme with the best performance. The effects of variations in the motor parameters are then analyzed, with the finding that a proper modeling of the motor makes the steady-state estimation of the disturbance torque insensitive to any variation. As a test, the schemes are applied to a sensorless DC motor drive for both compensating for the disturbance torque and closing the speed loop. The responses obtained with the best-performance scheme are reporte
Switched-reluctance motor performance analysis based on an improved modeling of its magnetic characteristics
No full textVariable structure control of an SRM drive
No full textThe applications of a variable-structure system (VSS) to the control of a switched reluctance motor (SRM) drive is presented. After reviewing the operation of an SRM drive, a VSS-based scheme is formulated to control the drive speed. The scheme is then designed and tested by simulation. The results show that the VSS control is effective in reducing the torque ripple of the motor, compensating for the nonlinear torque characteristics, and making the drive insensitive to parameter variations and disturbance
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
"Social Consensus: Contribution to Design Methods for AI Agents That Employ Personal Data
No full textThe emerging complex IoT ecosystems, embodied through Artificially Intelligent (AI) Agents on the front-end interaction with the user, rise many new considerations to be taken into account during the design process, among which the use of sensitive personal data. This paper introduces a case study, a concluded project of a system supported by AI algorithms for delivering tailored services to the drivers, including insurance offerings and supporting drivers in practicing safer driving style. We report on a segment of user studies done within this project that relates to the use of personal data, and we discuss the notion of emerged user values within. Accordingly, we observe and propose inclusion of social consensus considerations within the design process and evaluation of the same
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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