1,720,958 research outputs found
Inverse Thermal Analysis of Electrical Machines
No full textThis thesis focuses on the inverse thermal process of determining power losses of electrical machines from temperature measurements. The feasibility of this endeavour is investigated and the inverse mapping of losses with analytical and numerical thermal models of a 37 kW cage induction motor are demonstrated. Accurate lumped thermal networks as well as 2D and 3D finite element models of a 37 kW motor are built as forward thermal models for this purpose. Attention is given to managing error in measurement so that the temperature-to-source mapping can be accurate. The inverse mapping was achieved with two methods - least squares and conjugate gradient.
The results of the inverse mapping indicate that inverse thermal approaches hold promise in estimating losses in machine domains where direct measurements are cumbersome, such as the stator yoke or tooth regions. Lumped and distributed loss components could be recovered reliably using both inverse methods. Furthermore, a water-cooled calorimeter was designed and built to measure the total power loss of the induction motor. With only a few measured temperatures of the motor, the inverse thermal process is able to segregate the total losses into its constituent components
Design and Calibration of Water-Cooled Calorimeter for Induction Motors
Get PDFA balanced water-cooled calorimeter is designed and implemented for electromagnetic power loss measurement of a 37 kW induction motor. The electromagnetic losses of the induction motor are measured at different loads and no-load.
In order to meet the IEEE 841 Standard, the ambient temperature for the test motor must not exceed 40◦C. The efficiency for the test motor is 92%, and it is expected the upper limit for the power loss of the test motor is not higher than 3.7 kW. It is approved, the calorimeter is feasible to measure power loss up to 4 kW, while the air temperature in the chamber, near to the test object, is less than 40 ◦C.
Two calibration curves, one with 2 L/min and another one with 5L/min cooling flow rate are made conducted with a balance heater for the 37 kW induction motor. The first calibration curve is assigned for the total loss up to 2.5 kW and the latter for losses ranging from 2.5 to 4 kW. Using the calibration curves, reduce the balanced calorimetric measurement by almost 6 hours.
A heat-compensation method for the shaft heat-leakage is suggested and employed when the test motor is coupled with a loading machine. Experiments at no-load show the highest heat-leakage is due to the shaft heat-leakage. The uncertainty of the calorimetric measurement is 2.4% when the load torque is 201 Nm
Inverse Thermal Modeling to Determine Power Losses in Induction Motor
Get PDFAn electrical motor’s inverse thermal model formulates the precision with which its power losses can be predicted from noisy local temperature measurements. This paper proposes constrained linear least square optimisation followed by noise smoothing as a method to accurately predict a 37 kW induction motor’s power loss components. The anisotropic heat transfer and complex geometry of the motor is represented well by the motor’s lumped thermal network and 3D finite element models which characterise its intrinsic heat transfer processes. With the inverse solution method, satisfactory temperature to power inverse mapping was achieved for different sets of noisy temperature inputs simulated from analytical and numerical forward solutions. The paper demonstrates that even with measurement noise in input data, if reliable information about the expected response of the system is available, an accurate reconstruction of power losses can be achieved.Peer reviewe
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
