1,721,117 research outputs found
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
Improvements on Dislocation Dynamics Codes for the study of irradiated RPV ferritic steel's plasticity
No full textCes travaux de thèse s’inscrivent au sein d’une démarche multi-échelles visant à améliorer lacompréhension de la fragilisation par l’irradiation de l’acier de cuve. Dans ce cadre, nous nousintéressons à la description de la mobilité des dislocations dans la ferrite, l’une des entrées clépour les codes de dynamique de dislocations (DD). Nous présentons ainsi une revuebibliographique exhaustive des différentes théories et expressions de la mobilité, à partir delaquelle nous proposons une nouvelle expression pour les dislocations vis. Cette loi, utilisablepour la première fois dans le régime de transition ductile-fragile, permet de reproduire lesprincipales observations expérimentales disponibles à ce niveau. Finalement, nous montronsles améliorations apportées au code de DD Tridis BCC 2.0, qui intègrent la nouvelle loi demobilité avec une nouvelle gestion des segments de dislocation permettant de stabiliser etaccélérer des simulations complexes avec prise en compte du glissement dévié.The present work is part of a larger multi-scale effort aiming to increase knowledge of thephysical phenomena underneath reactor pressure vessel irradiation embrittlement. Withinthis framework, we focused on the description of dislocation mobility in BCC iron, which is oneof the key inputs to dislocation dynamics (DD) simulation codes. An extensive bibliographicreview shows that none of the available expressions can deal with the ductile-fragile transitiondomain of interest. Here, a new screw mobility law able to reproduce the main experimentalobservations is introduced building on the previous models. The aforementioned law is usedtogether with an improved dislocations dynamics code Tridis BCC 2.0, featuring bothperformance and dislocations segments interaction management enhancements, that allowsfor complex DD simulations of BCC iron structures with cross-sli
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
3D simulations of the interactions between crack and dislocations
No full textLa ténacité à la rupture est contrôlée non seulement par les paramètres macroscopiques mais aussi par la microstructure. Les défauts de la structure cristalline comme les lacunes, les inclusions ou les dislocations peuvent aussi grandement impacter la ténacité. Pour mieux comprendre ce phénomène, on mènera des simulations 3D d'un front de fissure interagissant avec des dislocations. Ces simulations visent à mesurer les variations des facteurs d'intensité des contraintes sur le front de fissure créées par la présence de dislocations. Pour cela, on combinera deux modèles préexistants : la méthode des éléments finis étendus (XFEM) et la dynamique des dislocations discrètes (DDD). XFEM est une évolution de la méthode des éléments fini qui permet l'étude d'une fissure qui se propage sans avoir besoin de remaillage, elle contrôlera le volume étudié, le chargement appliqué et la position de la fissure tandis que tant que la DDD contrôlera les dislocations, leur mouvement et leur multiplication. La précision du modèle crée sera testée en le comparant avec des résultats de simulations atomistiques. Pour mesurer qualitativement les effets des dislocations sur la ténacité, plusieurs dislocations avec des différents systèmes de glissement seront étudiées. D'autres paramètres comme la distance entre la fissure et la dislocation, la direction de la fissure, et la déformation initiale seront aussi étudiées. Pour comparer le modèle étudié avec des résultats provenant d'autres simulations, deux orientations de fissure seront simulées. Les dislocations étudiées ont des effets sur la fissure différents en fonction de leur système de glissement. Les résultats montrent des dislocations créant soit de l'écrantage, doit de l'anti-écrantage soit une combinaison des deux. Ces effets sont uniquement dépendants de la nature de la dislocation et ne changent pas quand la direction du vecteur de ligne de la dislocation change, ni quand la dislocation est plus éloignée de la fissure, même si l'intensité de l'effet change. De plus, les dislocations étant associées à un état de cisaillement local, elles affectent plus fortement KII que KI. KII contrôle aussi l'angle de propagation de la fissure, ce qui implique que les dislocations sont une des principales sources des déviations des fissures.Fracture toughness in materials is not only controlled by macroscopic parameters but also by the microstructure. The defects of the crystalline structure such as voids, inclusions or dislocations can also greatly impact toughness. To better understand this, 3D simulations of a crack front interacting with dislocations will be carried out. These simulations aim at measuring the variations of the stress intensity factors on the crack front caused by the presence of dislocations. To carry out these simulations, two preexisting models will be combined: Extended Finite Elements Method (XFEM) and Discrete Dislocation Dynamics (DDD). XFEM is an evolution of the Finite Elements Methods that allows the study of a propagating crack without needing to remesh, it will control the studied volume, the applied loading and the crack position while DDD controls the dislocations, their movement, and their multiplication. The accuracy of the created model is tested by comparisons with atomistic simulations. To test the effect of dislocations on toughness, several dislocations with different slip systems were studied. Other parameters such as dislocation crack distance, line direction, and initial strain were also studied. To compare the studied model with existing simulation results, two crack orientations were selected. The studied dislocations have different behaviors depending on their slip system. The results show dislocations creating shielding, antishielding or a combination of both. These effects are only dependent of the dislocation nature, and do not change when the dislocation line direction changes or if the dislocation is farther from the crack, though the intensity of the effect does change given these circumstances. Since the presence of dislocations is associated to a shear stress in their glide planes, it is found that they have more effect on KII than on KI. KII also controls the crack propagation angle, which means that the dislocations are one of the main sources of crack deviation
Experiments and simulations of interlocked materials
No full textLes structures autobloquantes sont des assemblages de blocs disposés périodiquement. La géométrie des blocs etles frottements entre blocs ainsi que la compression appliquée aux bords de l'assemblage jouent un rôle centraldans la cohésion de l'ensemble de l'assemblage. Des expériences d'indentation ont été menées pour étudier la réponse mécanique de matériaux autobloquants constitués de cubes en alumine et de blocs ostéomorphes enpolymère. Ces résultats ont été reproduits en utilisant deux méthodes numériques : la méthode des éléments finiset la méthode des éléments discrets utilisant un code dédié. Différentes variables de conception ont pu être étudiées par simulations numériques et les expériences nous ont permis de connaître la réponse d'un assemblage endommagé. De nouveaux assemblages à structure hierarchique ont été proposés et testés ouvrant de nouvellesperspectives.Interlocked materials are periodic paving of elementary blocks. The cohesion is insured by the boundary conditions applied on the edge of the assembly as well as the topology of the blocks and the friction between the blocks.Experiments were performed to study the mechanical response of interlocked assemblies built with cubes in alumina and osteomophic blocs in polymer. Those results have been reproduced using two numerical methods: the finite element method and the discret element method with the help of a dedicated code. Differents design parameters have been studied with numerical methods and experiments allowed us to know the response of a dammage assembly. New assemblies having a hierachical structure were proposed and tested opening new perspectives
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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