1,720,988 research outputs found
Interprétation et traitement des données de sonde atomique tomographique : application à la precipitation dans les Al-Mg-Si
No full textThe Al-Mg-Si-(Cu) alloys from the 6016 series are used in automobile industry asclosure panel sheets. They show a strong paint bake hardening behaviour (30 minutesat 185°C, typically). This behaviour comes from structural hardening : the diffusion ofthe solute elements in the supersaturated solid solution is activated by the heat treatmentand metastable phases precipitates form. These phases are coherent with the aluminiummatrix and slow the motion of the dislocations.The dimensions of these metastable phases are sometimes below 1 nm and makesthem difficult to analyse otherwise than with a tomographic atom probe. New techniquesof data interpretation and processing have been developed in this field in order to push theinstrument beyond its limits.With the help of the atom probe, sometimes associated with the transmission electronmicroscope, the beta" precipitation mechanisms have been elucidated. In particular, we haveshown that a preageing treatment (90°C) makes the ageing treatment more efficient. Thisis due to the formation of Mg- and Si-rich coherent clusters that increase the numberdensity of hardening objects (clusters + beta"). The presence of aluminium inside the b00precipitates has been demonstrated.The effect of the preageing treatment on the short range correlation between the soluteatoms during the very early stages of decomposition has been directly studied bythe use of partial pair correlation functions. By this method, we have also been able tosuggest a scheme for the natural ageing behaviour of the alloy : it could be explained bythe formation of solute atoms atmosphere in the vicinity of the dislocations. The interactionbetween dislocations and atmospheres could be responsible for the natural ageinghardening.Les alliages Al-Mg-Si-(Cu) de la série 6016 sont utilisés sous forme de tôles pourla réalisation d'ouvrants dans l'industrie automobile. Leur particularité est de pouvoirêtre durcis durant la cuisson des peintures (typiquement 30 minutes à 185°C). Ce phénomènes'explique par un durcissement structural : le traitement thermique de cuisson despeintures appliqué à une solution solide sursaturée active la diffusion des solutés et la précipitationde phases métastables plus ou moins cohérentes avec la matrice d'aluminiumqui vont ralentir le mouvement des dislocations.Ces différentes phases métastables ont des tailles extrêmement petites (parfois inférieuresà 1nm), ce qui les rend difficiles à analyser autrement qu'en sonde atomique tomographique.Une attention toute particulière a été apportée au développement de nouvellestechniques d'interprétation et de traitement des données afin de faire reculer les limites del'instrument.Grâce à la sonde atomique, parfois couplée au microscope électronique en transmission,les mécanismes de précipitation de la phase beta" ont été mieux compris. En particulier,nous avons montré qu'un traitement de prérevenu à 90°C appliqué avant le revenu rendaitce dernier plus efficace par la formation d'amas diffus de Mg et de Si qui augmentent ladensité numérique d'objets durcissants (amas +beta"). La présence d'aluminium dans lesprécipités a été démontrée.L'effet du prérevenu sur la corrélation entre les atomes durant les tout premiers stadesde décomposition a été étudié directement par le calcul de fonctions partielles de corrélationde paires. Cette méthode a également permis de suggérer un scénario expliquant ledurcissement pendant le stockage à l'ambiante par la formation d'atmosphères de solutésautour des dislocations, ralentissant ainsi leur mouvement
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
Kinetics of Precipitation in Metallic Alloys by Small Angle Scattering
No full textInternational audienc
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
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