1,720,959 research outputs found
Brazing transparent YAG to Ti6Al4V: Reactivity and characterization
No full textThe YAG/filler/Ti6Al4V system has been studied for the first time with the aim of producing brazed optical windows. Different fillers (AgCuTi, AgCu, Ag) and temperatures have been taken into account and the interfacial zones of the samples have been evaluated in terms of morphology and compositions. A thin and continuous metal-ceramic layer containing Ti is formed in contact with the YAG ensuring the adhesion between all the joined materials. The best joining results have been obtained at 850. °C, where we have observed the formation of an interfacial CuTi layer when AgCuTi and Ag have been used. No intermetallic compound formation was observed using the pure Ag at 970. °C and 1050. °C. The phase formation was interpreted using the CALPHAD method by means of recalculated Ag-Cu-Ti and Ag-Al-Ti isothermal sections. Microhardness tests have been conducted to evaluate the performances of the joints in terms of mechanical properties
Wettability of HfB2 by molten Ni(B) alloys interpreted by CALPHAD methods, Part 1: Definition of the B–Hf–Ni system
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Wettability of SiC and graphite by Co–Ta alloys: evaluation of the reactivity supported by thermodynamic calculations
No full textWithin the context of the design of high-temperature brazing process for C and SiC-based composites, a basic study is presented here about the wetting and interfacial reactivity of CoâTa alloys in contact with graphite or SiC. Wetting results are presented for the first time showing that CoâTa alloys wet C or SiC fairly or excellently depending on the relative amount of Ta. The final interfacial microchemistry and microstructures are the result of the interplay between the typical interfacial phenomena of the pure elements. Specifically, depending on the alloy composition, dissolution of the ceramic phase by Co or formation of a continuous interfacial layer of TaC that prevents dissolution prevails. The discussion about the interfacial reactivity between liquid CoâTa alloys and graphite or SiC, as well as the interpretation of solidification phenomena and the formation of interfacial phases, is supported by making reference to new multi-component phase diagrams calculated by CALPHAD method
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
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