1,720,969 research outputs found
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
Caractérisation expérimentale et modélisation des propriétés de rupture et de fragmentation dynamiques d'un noyau de munition et de céramiques à blindage
No full textSome ceramic grades, such as silicon carbide (SiC) or alumina (Al2O3), are used as ballistic materials thanks to their excellent mechanical performances, such as their hardness, while being light, where weight gain is a major issue for the design of military equipment for personal and vehicle protection. Since the Vietnam War, ceramics have been largely used and integrated as front face in bilayer shielding to stop the threat of AP (Armour Piercing)-type projectiles during a ballistic impact. Nevertheless, the projectile leads to an intense damage in the ceramic due to, amongst other phenomena, a dynamic tensile loading that manifests by multiple cracking, called fragmentation, particularly unfavourable for the integrity of the ballistic protection and its capacity to deal with a second impact. In order to develop a more performing shielding material, it is essential to understand the link between the microstructure of ceramics, the damage generated under impact and their ballistic performances.This thesis seeks to better understand the dynamic fragmentation phenomenon generated at high strain rates in high fracture-toughness ceramics, including a bio-inspired alumina material mimicking nacre microstructure. This artificial nacre is, a priori, more crack resistant than conventional ceramics as it is characterised by a high static fracture-toughness due to its specific “Brick-and-Mortar” (or BM) microstructure reproduced in the material called here MAINa.Certaines nuances de céramiques, comme les carbures de silicium (SiC) ou les alumines (Al2O3), sont utilisées comme matériaux balistiques en raison de leurs excellentes performances mécaniques, notamment leur dureté, tout en étant légères, là où le gain de masse est un enjeu majeur pour la conception d’équipements militaires de protection individuelle ou de véhicule. Depuis la guerre du Viêt Nam, les céramiques ont été largement utilisées et intégrées comme face avant de blindage bicouche pour stopper la menace des projectiles de type AP (Armour-Piercing) durant un impact balistique. Néanmoins, le projectile provoque un endommagement intense dans la céramique en raison, notamment, d’un chargement de traction dynamique qui se manifeste par une fissuration multiple, appelée fragmentation, particulièrement défavorable à l’intégrité de la protection balistique et à sa capacité à faire face à un second impact. Afin de développer un matériau de blindage plus performant, il est essentiel de comprendre le lien entre la microstructure des céramiques, l’endommagement généré sous impact et leurs performances balistiques.Cette thèse cherche à mieux comprendre le phénomène de fragmentation dynamique généré à hautes vitesses de déformation dans des céramiques à forte ténacité, incluant un matériau aluminé bio-inspiré de la nacre. Cette nacre artificielle est, a priori, plus réfractaire aux fissures que les céramiques conventionnelles car elle se caractérise par une haute ténacité statique en raison d’une microstructure spécifique de type « Brique-Mortier » (ou BM) reproduite dans le matériau appelé ici MAINa
Fragmentation "simple" d'un SiC poreux par nEOI
No full textRecorded with: an ultra-high-speed camera (Kirana(R) from Specialised Imaging); Test is: one-point-bar impact (1PB).Ceramic materials are being more and more used in bi-layer shielding solutions. When impacted, substantial tensile damage creates within the ceramic tile that manifests as numerous oriented cracks. Understanding the dynamic fracture response under high strain-rates and at the level of a single dynamic crack is of major importance in pushing forward the design of resilient ceramic-based armour solutions. Single fragmentation of brittle materials in dynamic is possible with adapted experimental techniques. For that, one of these methods is the notched-Edge-On-Impact (nEOI). This experimental method enables the study of a single quasi-straight dynamic crack which propagates through a single-notched rectangular specimen. When the projectile impacts the specimen, a compressive pulse propagates and reflects to the free end of the sample, thus changing of sign and becoming a tensile pulse. Once the tensile pulse arrives on the notch, if the stress intensity resulting from the stress concentration at the notch tip is sufficient, a crack initates. The crack propagation process is filmed with an ultra-high-speed camera with 5 million frames per second (5 Mfps), that is 0.2 μs of exposure time.→ This experimental technique, performed on a silicon carbide ceramic (Saint-Gobain's Forceram® SiC), can be used to characterise the dynamic crack velocity when coupled with Digital Image Correlation (DIC).Les matériaux céramiques sont de plus en plus utilisés dans les solutions de blindage à deux couches. Lors d'un impact, un endommagement substantiel en tension se crée dans le carreau de céramique comme des fissures nombreuses et orientées. Comprendre la réponse dynamique sous hauts taux de chargement et au niveau d'une fissure dynamique unique est d'une importance majeure pour faire progresser la conception de solutions pour blindage résiliant en céramique. La fragmentation simple de matériaux fragiles en dynamique est possible avec des techniques expérimentales adaptées. Pour cela, une de ces méthodes est l'impact-sur-tranche avec entaille (nEOI en anglais). Cette méthode expérimentale permet l'étude d'une fissure dynamique quasiment droite qui se propage à travers un échantillon rectangulaire simplement entaillé. Lorsque le projectile impacte l'échantillon, un pulse de compression se propage et se réfléchit en face arrière de l’échantillon, changeant ainsi de signe et devenant un pulse de tension. Une fois que le pulse de tension arrive sur l'entaille, si l’intensité de contrainte résultant de la concentration de contrainte en pointe d'entaille est suffisante, une fissure s'initie. Le processus de propagation de la fissure est filmé avec une caméra ultra-rapide avec 5 millions d'images par secondes (5 Mfps), c'est-à-dire avec 0,2 μs de temps d'exposition.→ Cette technique expérimentale, effectuée sur une céramique de carbure de silicium (SiC Forceram® de Saint-Gobain), peut être utilisée pour caractériser la vitesse d'une fissure dynamique quand couplée avec de la corrélation d'images numérique
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
Fractographie MEB d'un SiC poreux (nEOI)
No full textGeminiSEM 500® (Zeiss)One-point-bar impact (1PB impact, « impact central avec barre »)Ceramic materials are being more and more used in bi-layer shielding solutions. When impacted, substantial tensile damage creates within the ceramic tile that manifests as numerous oriented cracks. Understanding the dynamic fracture response under high strain-rates and at the level of a single dynamic crack is of major importance in pushing forward the design of resilient ceramic-based armour solutions. Single fragmentation of brittle materials in dynamic is possible with adapted experimental techniques. For that, one of these methods is the notched-Edge-On-Impact (nEOI). This experimental method enables the study of a single quasi-straight dynamic crack which propagates through a single-notched rectangular specimen. When the projectile impacts the specimen, a compressive pulse propagates and reflects to the free end of the sample, thus changing of sign and becoming a tensile pulse. Once the tensile pulse arrives on the notch, if the stress intensity resulting from the stress concentration at the notch tip is sufficient, a crack initates. The crack propagation process is filmed with an ultra-high-speed camera with 5 million frames per second (5 Mfps), that is 0.2 μs of exposure time.→ This experimental technique, performed on a silicon carbide ceramic (Saint-Gobain's Forceram® SiC), can be used to characterise the dynamic crack velocity when coupled with Digital Image Correlation (DIC). This image shows two locations of the fracture surface based on Scanning Electron Microscopy (SEM) with secondary electrons giving topography information. A transgranular brittle fracture is observed.Les matériaux céramiques sont de plus en plus utilisés dans les solutions de blindage à deux couches. Lors d'un impact, un endommagement substantiel en tension se crée dans le carreau de céramique comme des fissures nombreuses et orientées. Comprendre la réponse dynamique sous hauts taux de chargement et au niveau d'une fissure dynamique unique est d'une importance majeure pour faire progresser la conception de solutions pour blindage résiliant en céramique. La fragmentation simple de matériaux fragiles en dynamique est possible avec des techniques expérimentales adaptées. Pour cela, une de ces méthodes est l'impact-sur-tranche avec entaille (nEOI en anglais). Cette méthode expérimentale permet l'étude d'une fissure dynamique quasiment droite qui se propage à travers un échantillon rectangulaire simplement entaillé. Lorsque le projectile impacte l'échantillon, un pulse de compression se propage et se réfléchit en face arrière de l’échantillon, changeant ainsi de signe et devenant un pulse de tension. Une fois que le pulse de tension arrive sur l'entaille, si l’intensité de contrainte résultant de la concentration de contrainte en pointe d'entaille est suffisante, une fissure s'initie. Le processus de propagation de la fissure est filmé avec une caméra ultra-rapide avec 5 millions d'images par secondes (5 Mfps), c'est-à-dire avec 0,2 μs de temps d'exposition.→ Cette technique expérimentale, effectuée sur une céramique de carbure de silicium (SiC Forceram® de Saint-Gobain), peut être utilisée pour caractériser la vitesse d'une fissure dynamique quand couplée avec de la corrélation d'images numérique. Cette image montre deux lieux de la surface de fracture basée sur la Microscopie Électronique à Balayage (MEB) avec électrons secondaires donnant des informations sur la topographie. Une rupture fragile transgranulaire est observée
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