1,720,958 research outputs found
Complex TiC-Ni-based composites joined to steel support by thermal explosion under load: synthesis, microstructure and tribological behavior
No full textThe combustion in thermal explosion mode of reactive mixtures of Ti–Ni–graphite(carbides, borides, oxides), under load, was used to produce complex composite materials, densified and joined to a C55 carbon steel support. The ignition of the exothermic reaction, carried out thanks to the rapid high-frequency heating of a green compact up to 1573 K, was followed by an isothermal holding at 1373 K for 360 s. This procedure ensured a perfect mechanical assembly between the composite material and the steel substrate. SEM analysis and concentration profiles carried out at the interface testified to the interdiffusion of iron and titanium atoms between the two materials. The maximum combustion temperature (Tmax.) exceeding 2200 K induced the appearance of a liquid phase that assisted densification and joining, and in which a part of the additions was dissolved before cooling. The starting chemical composition of reactive mixtures largely determined the microstructure, hardness and tribological behavior of the composites after the process. Thereby, the maximum hardness (1235 HV0.15) and the lowest wear rate (1.824 × 10−6 mm3.N−1.m−1) were obtained in the sample containing TiC, Al2O3 and TiB2 hard phases. The manufactured samples exhibit no deterioration of the composite by spalling, regardless of the starting composition.Peer reviewe
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
Effet des additions sur la microstructure et le comportement tribologique et en fatigue thermique des revêtements à base de NiAl obtenus par projection plasma
Get PDFL’objectif principal de ce travail est de comprendre l’influence des additions des particules de TiC, SiC, MgO et WC dans le mélange de base NiAl, sur la structure, le comportement en fatigue thermique, à l’usure et par érosion du revêtement obtenu par projection plasma (APS). La microstructure des revêtements a montré une structure lamellaire, caractéristique des revêtements obtenus par projection plasma. Le revêtement NiAl+5%WC a acquis ainsi une dureté plus élevée que les autres revêtements. L'essai de fatigue thermique a été réalisé par un chauffage cyclique par effet joule dans l’intervalle 100 et 800°C . Les résultats expérimentaux ont montré que le revêtement enrichi en WC présente le meilleur comportement en fatigue thermique. Les essais d'érosion ont été effectués à température ambiante avec un angle d'attaque de 90°. Le coefficient de frottement a été déterminé sous une charge normale de 5N, avec une vitesse de 11,31 cm/s et à température ambiante. Le revêtement NiAl accuse le plus bas coefficient de frottement. L'incorporation des autres particules améliore le comportement à l’érosion ainsi que le coefficient de frottement.Mots-clés: Fatigue thermique- érosion- projection plasma-revêtement NiAl- coefficient de frottementEnglish Title: The effect of additions on the microstructure, tribological behavior and thermal fatigue of the NiAl coating, obtained by atmospheric plasma spraying (APS)English AbstractThe main focus of this work is to highlight the influence of the TiC, SiC, MgO and WC particles, as additions on the microstructure, thermal fatigue and tribological tests of the NiAl coating, obtained by atmospheric plasma spraying (APS). It was founded that the NiAl–5%WC microhardness and thermal fatigue behaviour were more improved than the TiC, MgO, and SiC coatings. In addition, the MgO, WC, SiC and TiC coatings showed lower erosion rates compared to NiAl base ones. However, the thermal fatigue and erosion tests were conducted by a cyclic heating Joule effect within the range 100–800 °C degrees and at room temperature with an attack angle of 90° respectively.. Furthermore, the microstructure of all the coatings showed a lamellar morphology, which is typical of the coatings obtained by atmospheric plasma spraying. The friction coefficient was determined under a normal load of 5 N with sliding speed of 11.31 cm/s and at room temperature. The NiAl coating present the lowest coefficient of friction. The incorporation of the particles improves the coefficient of frictionKeywords: Thermal fatigue-erosion-plasma Spray-NiAl coating-friction coefficien
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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