1,721,012 research outputs found
Oxidation characteristics of Ti3AlC2, Ti3SiC2 and Ti2AlC
No full textMAX phases display a unique combination of characteristics of both metals and ceramics, and unusual mechanical, electrical and thermal properties. In this chapter, the oxidation characteristics of Ti3AlC2, Ti3SiC2 and Ti2AlC over the temperature range 500-1400 °C were studied by synchrotron radiation diffraction, neutron diffraction, secondary-ion mass spectrometry (SIMS) and nuclear magnetic resonance (NMR) experiments, which provided elemental and phase compositional depth profiles over this range as well as evidence of glassy phase formation. Evidence for the outward diffusion of Al or Si during oxidation was shown for the first time by the complementary SIMS and NMR results, suggesting amorphous Al or Si at low temperature oxidation, which is vital for strong adherent oxide scales during oxidation. During oxidation, anatase formed at 500 °C, which transformed to rutile at 600 °C and was completed by 900 °C. The crystalline phase alpha-Al2O3 was detected at 900 °C in Ti3AlC2 or Ti2AlC. Tridymite and cristobalite were detected at 1000 and 1350 °C respectively in Ti3SiC2
Phase and thermal stability in Ti3SiC2 and Ti3SiC2/TiC/TiSi2 systems
No full textIt is known that Ti3SiC2 is the only stable ternary compound in the Ti-Si-C system; however the preparation of pure Ti3SiC2 is very difficult as there are always impurities. The properties of these Ti3SiC2 composites can be enhanced or weakened by these impurities. In this chapter, the effect of argon and high vacuum annealing on the phase stability and phase transitions of highly-pure Ti3SiC2 and Ti3SiC2/TiCx/TiSi2 composites up to 1550 dgreesC has been studied using in situ neutron diffraction. The role of TiCx and/or TiSi2 in the thermal stability of Ti3SiC2 during argon or vacuum annealing has been discussed. The mechanism of Ti3SiC2 decomposition in vacuum has also been proposed. The decomposition rate of Ti3SiC2 was both dependent on temperature and dwell time, and exhibited a linear relationship with the dwell time and increased with temperature. Furhtermore, the activation energy for the formation and decomposition of Ti3SiC2 was determined using the Arrhenius equation. The kinetics of isothermal phase decomposition at 1500 degreesC was modelled using a modified Avrami equation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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