1,720,956 research outputs found
The comparative study of the specific heat capacity of uranium dioxide according to the fractal structure
Get PDFIn the present study, we investigate the effectiveness of existing methods for evaluating the heat capacity of uranium dioxide (UO2) by considering the fractal structure of materials. Two well-known theoretical methods were investigated in this work which have the advantages of giving accurate and efficient calculation results for the heat capacities of uranium dioxide for a wide range of temperatures. To verify the effectiveness of these theoretical methods, we compare the calculation results with existing experimental data from the literature. Based on the concept of fractality, the results obtained in this work are useful for determining the best theoretical approaches, i.e., those that are more convenient and meaningful for the evaluation of the heat capacities of uranium dioxide. The approaches and results presented in this study can provide useful knowledge for accurate investigations of the physical properties of other nuclear fuels
Full Analytical Evaluation of the Einstein Relation for Disordered Semiconductors
No full textWe present a simple analytical method for the evaluation of the Einstein relation for disordered semiconductors with exponential distribution of tail states. The proposed analytical method is based on the binomial expansion theorems, and the calculation result permitted an accurate evaluation of the validity of the analytical approximation, as well as further improvement of the theoretical formulas. The accuracy and the efficiency of the obtained formulas of the Einstein relation for disordered semiconductors are demonstrated with the comparison of the numerical and analytical results. The formulas can be used to analyze the experimental results
An analytical evaluation method of the temperature dependence of resistive losses in electric motors
No full textIn this work, the temperature dependence of motor resistive losses has been analytically evaluated by using a quantum mechanical approximation. It is well known that the Bloch-Gruneisen approximation is a fundamental quantum theory to the study of the resistivity of the conductor with the change of temperature by using analytical formulation. By using the proposed method, the motor resistive losses can be controlled with respect to the temperature changes. The accuracy of the proposed algorithm has been tested by comparison with different theoretical approaches. It is demonstrated that the new analytical method for the motor resistive losses controlled with the change of temperature will be used for improving motor power and mechanical systems
Analytical investigation of thermodynamic properties of power electronic semiconductor materials
No full textTheoretical and experimental investigations are critical for accurately investigating the structure and physical properties of semiconductors, allowing their widespread use in power electronic devices. The heat capacities are important thermal properties needed to examine the electronic and electrical properties of device materials. The specific heat capacities of power electronic semiconductors, such as (GaN\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document}) gallium nitride, (SiC\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document}) silicon carbide, (Ga2O3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}\end{document}) gallium oxide, and diamond, have been evaluated theoretically using the recently developed Einstein-Debye approximation. On the grounds of the Einstein-Debye approach, the derived general analytical expression for the calculation of the heat capacities is valid for the entire temperature range. The calculation results are compared with the previously available experimental and theoretical data for illustrating the correctness of the method. The evaluation and literature analysis confirm the effectiveness of the proposed method. As seen from the comparison with various results reported in the literaure, the results obtained from this approach are convenient and competitive
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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