1,720,995 research outputs found
Investigation of inverterless control of interior permanent magnet alternators
No full textCopyright © 2004 IEEEThis paper investigates the performance and control of a low-cost 6 kW concept demonstrator of an 'inverterless' automotive alternator. This is based on a switched-mode rectifier combined with a high-flux interior permanent magnet machine. Duty-cycle control of the alternator is described and the theoretical predictions are compared with open-loop experimental results. The efficiency of the concept demonstrator is examined as a function of speed and load. Control issues regarding automotive operation are discussed.C.Z. Liaw, D.M. Whaley, W.L. Soong and N. Ertugru
Finite-element analysis and design of a radial-field brushless PM machine utilizing soft magnetic composites
No full textSoft magnetic composites (SMC) are emerging in electrical machine design offering the potential for innovative machine geometries and lower cost manufacturing. This paper examines the design and analysis of a SMC-based radial-field fractional-slot concentrated-winding permanent magnet machine using 2D finite-element analysis. Its performance is compared with an existing conventionally-laminated, distributed-winding baseline design for two cases, firstly with the same active stack length and secondly with the same end-winding stack length.G.S. Liew, C. Tang, W.L. Soong, N. Ertrugul and D.B. Gehler
Output power capability of surface PM generators with switched-mode rectifiers
No full textSurface permanent magnet (SPM) machines operate with maximum output power for a given current when the induced voltage and the current are in phase. For an SPM generator this is obtained with a leading power-factor load. The inverter topology can achieve a leading input power-factor but this generally requires rotor position information. A lower-cost approach is to use a switched-mode rectifier (SMR) however with conventional modulation control its unity power factor operation results in a lower output power capability, particularly at low speeds. This paper examines performance of phase advance modulation methods to improve the lowspeed output power capability of SPM generators when operated with a SMR. A simplified phase advance modulation called zero-epsilon is proposed. Analytical and simulation approaches are used to understand the fundamental limitations, and the results are then confirmed experimentally.M. Pathmanathan, W.L. Soong and N. Ertugru
Investigation and development of a real-time on-site condition monitoring system for induction motors
No full textCondition monitoring of induction motors is commonly used in industrial applications to maintain safe and reliable operation of plants. The current practice in condition monitoring primarily involves using various forms of mobile devices usually with a single sensor input to perform tests at regular intervals. However, such devices and monitoring services are expensive and require an experienced operator for reliable decisions. This paper investigates an alternative low cost solution for continuous condition monitoring of induction machines using multiple sensors, which can be located next to a machine under test and can provide condition information using indicator lights for quick diagnosis. In addition, the paper provides the hardware and software details of the system implemented which are based on an FPGA based (CompactRIO) LabVIEW platform. A number of test results are also provided in the paper to demonstrate its performance under real faults.S. Bakhri ; N. Ertugrul ; W.L. Soong ; and S. Al-Saraw
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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