1,721,050 research outputs found
Evaluation of anisotropic thermoelectric power of ReSi1.75
No full textThe highly anisotropic transport properties of ReSi1.75 single crystals have been evaluated with the Boltzmann transport equation under the assumption that the deformation potential acoustic phonon scattering is dominant. There is a large difference between the calculated transport properties and the measured properties along [100], while there is little difference between the calculated and the measured along [001]. The intervalley scattering mechanism is proposed as the reason of the discrepancy in the transport properties along [100]. It is also shown that the large effective mass of holes along [001] restrict the contribution of the holes in transporting the energy induced by the Seebeck effect, resulting in good thermoelectric conversion efficiency. (c) 2006 Elsevier B.V. All rights reserved
水素吸蔵合金における水素侵入機構-水素吸蔵過程における格子欠陥の生成に注目して-
Get PDF平成12-13年度科学研究費補助金(基盤研究(B)(2))研究成果報告書 課題番号：12450282 研究代表者：乾晴行(京都大学工学研究科助教授
The Plaston Concept
Get PDFThis open access book presents the novel concept of plaston, which accounts for the high ductility or large plastic deformation of emerging high-performance structural materials, including bulk nanostructured metals, hetero-nanostructured materials, metallic glasses, intermetallics, and ceramics. The book describes simulation results of the collective atomic motion associated with plaston, by computational tools such as first-principle methods with predictive performance and large-scale atom-dynamics calculations. Multi-scale analyses with state-of-the art analytical tools nano/micro pillar deformation and nano-indentation experiments are also described. Finally, through collaborative efforts of experimental and computational work, examples of rational design and development of new structural materials are given, based on accurate understanding of deformation and fracture phenomena. This publication provides a valuable contribution to the field of structural materials research
The Plaston Concept
Get PDFThis open access book presents the novel concept of plaston, which accounts for the high ductility or large plastic deformation of emerging high-performance structural materials, including bulk nanostructured metals, hetero-nanostructured materials, metallic glasses, intermetallics, and ceramics. The book describes simulation results of the collective atomic motion associated with plaston, by computational tools such as first-principle methods with predictive performance and large-scale atom-dynamics calculations. Multi-scale analyses with state-of-the art analytical tools nano/micro pillar deformation and nano-indentation experiments are also described. Finally, through collaborative efforts of experimental and computational work, examples of rational design and development of new structural materials are given, based on accurate understanding of deformation and fracture phenomena. This publication provides a valuable contribution to the field of structural materials research
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
Plasticity of hard and brittle materials at micron-meter size scales
Get PDFThere are many hard materials that are considered to be candidates for structural applications under extreme conditions such as very high temperatures. This stems from the fact that many of them possess peculiar properties such as high hardness, high melting temperature, and so on. But, one of the common characteristics for these hard materials is their brittleness. They usually fail in cleavage without showing any plastic deformation at ambient temperature. So, even, fundamentals for plasticity such as operating slip systems and their CRSS values have yet to be known for many of them. If we assume that fracture in these hard materials occurs in a brittle manner at a pre-existing micro-crack, the effective defect size of the microcrack to cause fracture is believed to vary with the fracture toughness (KIC) at a given fracture stress. If the fracture stress is fixed at 1 GPa, the effective defect size of the micro-crack is calculated to be 320 nm for KIC of 1 MPam-1/2, but this value increases to about 8 mm if the KIC values is increased to 5 MPam-1/2. Then, there is a chance for these hard materials to plastically deform in the form of micropillars of the micron-meter size even at ambient temperature.
We have investigated the compression deformation behavior of transition-metal silicides as typical examples of hard materials such in the micropillar form with the specimen size ranging from 0.5 to 10 mm at room temperature. Those hard materials include transition-metal (M) silicides of the M5Si3-type such as Mo5Si3, Nb5Si3 and Mo5SiB2 and those of the MSi2-type such as MoSi2, VSi2, CrSi2, NbSi2 and TaSi2. Although none of them listed above deform plastically at room temperature in the bulk form, plasticity is clearly observed at room temperature for all of them in the micropillar forms. This is very surprising in particular for transition-metal silicides of the M5Si3-type, since they usually need more than 1300°C for their plastic deformation to occur in the bulk form. Because of such a high temperature, slip systems have never been identified with confidence for these transition-metal silicides of the M5Si3-type. However, plasticity observed in the micropillar form at room temperature has made us to clearly identify their operative slip systems with their CRSS (critical resolved shear stress) values. For transition-metal silicides of the MSi2-type, slip systems operative at high temperatures in the bulk form are observed also to operate in the micropillar form at room temperature. The room-temperature bulk CRSS values for these slip systems can be obtained by extrapolating the power-law of the CRSS-specimen size dependence to the bulk size, which can be estimated to be 30-50 m. The room-temperature bulk CRSS values thus estimated are on the extension of the CRSS-temperature curve of the corresponding slip system for some silicides but not for other silicides. The origin of the latter behavior is proved to be due to a transition of deformation mechanisms
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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