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From bi-dimensional discrete model to anisotropic damage model: a feasibility study
No full textInternational audienceThis study investigates using a discrete model (explicitly representing micro-cracking) as a "virtualtest machine". Anisotropic damage models often require complex experiments to be formulated andidentified. Discrete models could reduce the experimental cost of formulating an anisotropic damagemodel. A beam particle model represents a 2D square specimen of quasi-brittle material in this work. Adamaging loading is applied to the specimen until the localization of micro-cracking. The evolution ofthe effective elasticity tensor is measured at each load step through elastic loadings. The measurementprocedure is then illustrated with a tensile loading. Harmonic decomposition is used to analyze thisevolution. The analysis of the evolution highlights the correlation between micro-cracking and stiffnessloss. Additionally, calculating distances to symmetry classes allows quantifying anisotropy induced bymicro-cracking. Eventually, it will provide a means to build an anisotropic damage model based onharmonic decomposition.Ce travail étudie l'utilisation d'un modèle discret (qui représente explicitement la fissuration) comme une "machine d'essai virtuelle". En général, des expériences complexes sont requises pour formuler et identifier les modèles d'endommagement anisotropes. L'utilisation d'un modèle discret permettrait de réduire de coût experimental nécessaire à la formulation d'un modèle discret. Dans cette étude, un modèle beam-particle représente une éprouvette bidimensionnelle carrée. Un chargement endommageant est appliqué sur l'éprouvette jusqu'à la localisation de la micro-fissuration. L'évolution du tenseur d'élasticité effectif est mesurée à chaque instant via des chargements de mesure élastiques. Pour conclure, la procédure est illustrée sur un cas de traction. La décomposition harmonique est utilisée pour analyser les résultats. Cette analyse montre la correlation entre micro-fissuration et perte de rigidité. De plus, les calculs des distances aux classes de symétries permettent de quantifier l'anisotropie induite par la micro-fissuration. Cette étude pose les bases d'un projet plus complet visant à construire un modèle d'endommagement anisotrope basé sur la décomposition harmonique
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
Formulation de l'endommagement anisotrope des matériaux et stuctures quasi-fragiles basée sur la simulation discrète de la fissuration
No full textLes matériaux quasi-fragiles, couramment utilisés pour les structures du génie civil, ont tendance à se dégrader lorsqu'ils sont soumis à des chargements mécaniques. Cette dégradation induit une perte de propriété mécanique et peut induire une anisotropie du comportement qui dépend de la direction du chargement. La prédiction de cette dégradation et de son impact sur le matériau est un enjeu important pour garantir l'intégrité des structures et la sécurité des usagers. Cette problématique est au cœur de ce travail qui vise à formuler un modèle d'endommagement anisotrope (macroscopique) pour les matériaux quasi-fragiles en 2D. Pour ce faire, une base de donnée de tenseurs d'élasticité est générée par essais "virtuels''. Un élément d'aire (mésoscopique) du matériau est représentée par un modèle discret beam-particle fournissant une description explicite de la micro-fissuration. L'évolution du tenseur d'élasticité effectif de l'élément est mesurée pour différents chargements (dont certains multiaxiaux et non proportionnels). L'analyse des tenseurs par le calcul des distances aux classes de symétrie montre qu'une variable tensorielle d'ordre au moins deux est nécessaire pour décrire la micro-fissuration. Afin de faciliter la construction du modèle d'état, une formule de reconstruction du tenseur d'élasticité par ses covariants ainsi qu'une variable d'endommagement sous-jacente, toutes deux issues de travaux précédents, sont rappelées. En se basant sur ces outils ainsi que sur la base de donnée générée, un modèle du tenseur d'élasticité effectif en fonction de la variable d'endommagement, i.e. un modèle d'état, est proposé puis évalué. Concernant la modélisation de l'évolution, la fonction critère de l'élément d'aire est déterminée puis calibrée par essais "virtuels''. Enfin, après une analyse de l'évolution de l'endommagement dans la base de donnée, un modèle (préliminaire) non-standard de l'évolution de l'endommagement est proposé.Quasi-brittle materials, commonly found in civil engineering structures, tend to degrade when submitted to mechanical loadings. This degradation leads to a loss in mechanical properties and can induce anisotropy of the material behavior, which depends on the loading direction. Predicting this degradation and its impact on the material is essential to guarantee the integrity of structures and the safety of users. This problem is at the heart of this work, which aims to formulate a (macroscopic) anisotropic damage model for quasi-brittle materials in 2D. To this end, a dataset of effective elasticity tensors is generated by "virtual'' testing. A (mesoscopic) area element of the material is represented by a discrete beam-particle model, which provides an explicit description of micro-cracking. The evolution of the element's effective elasticity tensor is measured for various loadings (some of which are multiaxial and non-proportional). The analysis of the measured tensors by calculating distances to symmetry classes shows that a tensor variable of order two or higher is needed to describe micro-cracking. To facilitate the formulation of the state model, a formula for reconstructing the elasticity tensor from its covariants and an associated damage variable, both derived from previous work, are recalled. Based on these tools and the generated dataset, a model of the effective elasticity tensor as a function of the damage variable, i.e. a state model, is proposed and evaluated. For evolution modeling, the criterion function of the area element is determined and calibrated by "virtual'' testing. Finally, a (preliminary) non-standard evolution model is proposed after an analysis of the damage evolution in the dataset
Formulation de l'endommagement anisotrope des matériaux et stuctures quasi-fragiles basée sur la simulation discrète de la fissuration
No full textQuasi-brittle materials, commonly found in civil engineering structures, tend to degrade when submitted to mechanical loadings. This degradation leads to a loss in mechanical properties and can induce anisotropy of the material behavior, which depends on the loading direction. Predicting this degradation and its impact on the material is essential to guarantee the integrity of structures and the safety of users. This problem is at the heart of this work, which aims to formulate a (macroscopic) anisotropic damage model for quasi-brittle materials in 2D. To this end, a dataset of effective elasticity tensors is generated by "virtual'' testing. A (mesoscopic) area element of the material is represented by a discrete beam-particle model, which provides an explicit description of micro-cracking. The evolution of the element's effective elasticity tensor is measured for various loadings (some of which are multiaxial and non-proportional). The analysis of the measured tensors by calculating distances to symmetry classes shows that a tensor variable of order two or higher is needed to describe micro-cracking. To facilitate the formulation of the state model, a formula for reconstructing the elasticity tensor from its covariants and an associated damage variable, both derived from previous work, are recalled. Based on these tools and the generated dataset, a model of the effective elasticity tensor as a function of the damage variable, i.e. a state model, is proposed and evaluated. For evolution modeling, the criterion function of the area element is determined and calibrated by "virtual'' testing. Finally, a (preliminary) non-standard evolution model is proposed after an analysis of the damage evolution in the dataset.Les matériaux quasi-fragiles, couramment utilisés pour les structures du génie civil, ont tendance à se dégrader lorsqu'ils sont soumis à des chargements mécaniques. Cette dégradation induit une perte de propriété mécanique et peut induire une anisotropie du comportement qui dépend de la direction du chargement. La prédiction de cette dégradation et de son impact sur le matériau est un enjeu important pour garantir l'intégrité des structures et la sécurité des usagers. Cette problématique est au cœur de ce travail qui vise à formuler un modèle d'endommagement anisotrope (macroscopique) pour les matériaux quasi-fragiles en 2D. Pour ce faire, une base de donnée de tenseurs d'élasticité est générée par essais "virtuels''. Un élément d'aire (mésoscopique) du matériau est représentée par un modèle discret beam-particle fournissant une description explicite de la micro-fissuration. L'évolution du tenseur d'élasticité effectif de l'élément est mesurée pour différents chargements (dont certains multiaxiaux et non proportionnels). L'analyse des tenseurs par le calcul des distances aux classes de symétrie montre qu'une variable tensorielle d'ordre au moins deux est nécessaire pour décrire la micro-fissuration. Afin de faciliter la construction du modèle d'état, une formule de reconstruction du tenseur d'élasticité par ses covariants ainsi qu'une variable d'endommagement sous-jacente, toutes deux issues de travaux précédents, sont rappelées. En se basant sur ces outils ainsi que sur la base de donnée générée, un modèle du tenseur d'élasticité effectif en fonction de la variable d'endommagement, i.e. un modèle d'état, est proposé puis évalué. Concernant la modélisation de l'évolution, la fonction critère de l'élément d'aire est déterminée puis calibrée par essais "virtuels''. Enfin, après une analyse de l'évolution de l'endommagement dans la base de donnée, un modèle (préliminaire) non-standard de l'évolution de l'endommagement est proposé
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
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