1,720,972 research outputs found
Ball Milling and Spark Plasma Sintering of Cerium Silicides as a Surrogate Nuclear Fuel
No full textUranium silicide (U3Si2) is under consideration as a more uranium-dense replacement for UO2 in Light Water Reactors. Fuel pellets are typically produced by arc melting, crushing, and pressureless sintering, but this process is slow and resulting fuel is porous and inhomogeneous. Ball milling and Spark Plasma Sintering (SPS) are two novel processing techniques that are being investigated to achieve high density, compositionally homogenous fuel with minimal processing time. In this study, cerium silicides were used as a surrogate material to investigate the feasibility of high-energy ball milling and Spark Plasma Sintering (SPS) for the production of uranium silicide. Ball milling was studied as a function of time and composition. Each milled composition was then sintered by pressureless and SPS techniques. Samples were characterized after milling and after sintering by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) to determine morphology, composition, and phase purity. The characterization results show that high-energy ball milling produces homogeneous alloys in less than one hour, while SPS processing greatly reduces porosity and saves considerable time in sintering. This work verifies that these novel processing techniques produce superior results when compared to more traditional fabrication methods
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
Effects of Sintering Aids on Hydrothermal Corrosion Behavior of Si3N4 Ball Bearings
No full textSilicon nitride (Si3N4) bearings are being incorporated into aeropropulsion applications that require high strength, hardness, and chemical stability at elevated temperatures. Sintering aids such as yttria (Y2O3), alumina (Al2O3), titania (TiO2) and magnesia (MgO) are added during processing to promote densification and enhance microstructure, but minor changes in composition can significantly alter corrosion behavior of monolithic Si3N4. The hydrothermal corrosion behavior of a silicon nitride bearing that includes TiO2, Y2O3, and Al2O3 additives was compared to more common Si3N4 composites. The bearings were corroded in an autoclave at 250-300°C and 750-2400 psi for 12-48 hours and subsequently characterized with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and inductively coupled plasma mass spectrometry (ICPMS). The corrosion resistance of the TiO2/Y2O3/Al2O3-doped Si3N4 ceramic closely matches that of Y2O3/Al2O3-doped Si3N4 and outperforms Al2O3/MgO-doped Si3N4. This study demonstrates the stability of the TiO2/Y2O3/Al2O3-doped Si3N4 ceramic composition and verifies its potential as a bearing material in aeropropulsion applications
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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