1,720,977 research outputs found
Applicability of the indentation-strength method to the measurement of the crack resistance curve in brittle materials
No full textCharacterisation of plasma sprayed W coatings on a CuCrZr alloy for nuclear fusion reactor applications
No full textMock-ups of thermal shields for international thermonuclear experimental reactor (ITER) have been manufactured by depositing 5-mm-thick W coatings on a CuCrZr alloy (ELBRODUR(R)). Coatings, made by controlled atmosphere plasma spray technique. have low porosity and excellent thermal fatigue resistance under high heat flux. Their structure has been investigated by scanning electron microscopy (SEM), scanning tunnel microscopy (STM), energy dispersion spectroscopy (EDS) and inductively coupled plasma (ICP) analysis. In spite of the remarkable thermo-mechanical properties of coatings, the present work evidenced some flaws (small cracks, unmolten W particles and presence of Ni in the external layers). Quality of coatings may be improved by strictly controlling purity and granulometry of sprayed W powders and some process parameters. (C) 2002 Elsevier Science B.V. All rights reserved
Strain gradients in plasma-sprayed zirconia thermal barrier coatings
No full textNeutron diffraction was used to measure the residual strain field in plasma-sprayed zirconia thermal barrier coatings (TBCs). Data were collected at the British neutron spallation source of ISIS (Didcot), on ENGIN, a recently installed TOF (time-of-flight) instrument designed for residual strain depth profiling. Its particular geometry permitted a direct measurement of the interplanar distances of crystallographic planes lying parallel to the component surface as well as the measurement of zero-strain reference samples. The latter were annealed samples of the three present phases: zirconia (top coat), NiCoCrAlY (bondcoat), and copper (substrate). In this way epsilon(33), the strain component perpendicular to the sample surface, was determined at several positions inside the component, for all the present phases. The results of this analysis, consisting of a strain profile throughout the entire cross-section of the coated component, were integrated by those obtained by a destructive testing, performed after TOF data collection, consisting in the measurement of curvature change of the ceramic after substrate removal by chemical attack. (C) 1998 Elsevier Science S.A. All rights reserved
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
Residual stress in partially-stabilised-zirconia TBCs: experimental measurement and modelling RID A-9634-2010
No full textThe residual stress field in 7wt% yttria partially stabilised zirconia (Y-PSZ) plasma sprayed (300-mu m thick) coatings on Al substrates was studied by means of two different techniques: X-ray residual stress analysis (XRSA), and elongation and curvature measurement after substrate removal (CD), Results were considerably improved with respect to conventional XRSA, by using a synchrotron radiation source and specifically designed high resolution optics: an extended beam penetration, achieved by using different wavelengths down to 0.94 Angstrom allowed the determination of the strain field in the outer similar to 50 mu m of the ceramic. XRSA (surface) and CD (volume averaged) strain data were analysed by a mechanical model of the coated component capable of intergrating the results of both techniques. The procedure, designed to appropriately consider the different nature of the information coming from the two measurement techniques, permitted us to study the residual stress distribution through the entire Y-PSZ coating thickness. In particular, it pointed out the presence of a considerable stress gradient in the surface region of the ceramic. (C) 1997 Elsevier Science S.A
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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