1,720,959 research outputs found
Modélisation de l’endommagement et de la fissuration dynamique par une approche à champs de phase, implémenté dans un cadre de résolution temporelle explicite
No full textMalgrè les avancées majeures en dynamique de la rupture, ce mécanisme reste une problématique industrielle d’actualité due à son caractére souvent imprévisible. Les méthodes numériques sont des approches de plus en plus déployées pour aider à une meilleure compréhension de ces mécanismes. Les modèles à gradient d’endommagement ont connu un intérêtcroissant pour modéliser la rupture fragile quasistatique et commence à être de plus en plus utiliser pour de la rupture dynamique. Son utilisation reste limiter à l’échelle du laboratoire. Ces modèles requièrent un raffinement de maillagenon négligeable. Couplé à des méthodes de résolution implicite, les coûts de calcul à l’échelle industrielle deviennent rédhibitoire. Nous proposons, dans ces travaux, une résolution des équations du modèle à partir de schéma explicite.Ce choix requiert des formulations d’endommagement dynamiques en vitesse d’endommagement et/ou en accélération d’endommagement. Ceci pose également la question de l’intérêt physique de telles formulations. Des effets non négligeablede l’ajout d’une viscosité d’endommagement et d’inertie d’endommagement ont été mis en évidence par rapport à une évolution de l’endommagement gouvernée par une équation elliptique. Ces extensions ont montré des résulats prometteurs dans le contrôle de la vitesse de l’endommagement, mais ont soulevé en parallèle quelques faiblesses notamment des épaississements de “fissure”.Dynamic fracture a complex phenomenon that remains challenging to predict, posing significant difficulties for industrial applications. Since the early 21st century, numerical approaches have become widely adopted to investigate transient fracture mechanisms. Among these, damage gradient models have gained increasing attention for modeling brittle fracture in both quasi-static and transient regimes. However, these models are predominantly restricted to academic research due to several limitations, one of the most significant being the high computational cost due to both fine mesh requirements and expensive resolution strategies. These present studies propose an alternative resolution strategy in which the model equations are integrated using an explicit time integration scheme. This approach needs the use of timedependent damage formulations, which may be either first- or second-order leading to parabolic or hyperbolic partial differential equation, respectively.Extending the damage formulation to rate dependent model or damage inertia also raises fundamental physical questions about their necessity. The findings of this study demonstrate the influence of incorporating damage viscosity and inertia on both the crack path and crack tip speed, compared to the behaviour predicted by a standard elliptic damage PDE. While these extensions yield promising resultats in capturing dynamic damage evolution, the issue of damage thickening remains a challenge to address
Modélisation de l’endommagement et de la fissuration dynamique par une approche à champs de phase, implémenté dans un cadre de résolution temporelle explicite
No full textDynamic fracture a complex phenomenon that remains challenging to predict, posing significant difficulties for industrial applications. Since the early 21st century, numerical approaches have become widely adopted to investigate transient fracture mechanisms. Among these, damage gradient models have gained increasing attention for modeling brittle fracture in both quasi-static and transient regimes. However, these models are predominantly restricted to academic research due to several limitations, one of the most significant being the high computational cost due to both fine mesh requirements and expensive resolution strategies. These present studies propose an alternative resolution strategy in which the model equations are integrated using an explicit time integration scheme. This approach needs the use of timedependent damage formulations, which may be either first- or second-order leading to parabolic or hyperbolic partial differential equation, respectively.Extending the damage formulation to rate dependent model or damage inertia also raises fundamental physical questions about their necessity. The findings of this study demonstrate the influence of incorporating damage viscosity and inertia on both the crack path and crack tip speed, compared to the behaviour predicted by a standard elliptic damage PDE. While these extensions yield promising resultats in capturing dynamic damage evolution, the issue of damage thickening remains a challenge to address.Malgrè les avancées majeures en dynamique de la rupture, ce mécanisme reste une problématique industrielle d’actualité due à son caractére souvent imprévisible. Les méthodes numériques sont des approches de plus en plus déployées pour aider à une meilleure compréhension de ces mécanismes. Les modèles à gradient d’endommagement ont connu un intérêtcroissant pour modéliser la rupture fragile quasistatique et commence à être de plus en plus utiliser pour de la rupture dynamique. Son utilisation reste limiter à l’échelle du laboratoire. Ces modèles requièrent un raffinement de maillagenon négligeable. Couplé à des méthodes de résolution implicite, les coûts de calcul à l’échelle industrielle deviennent rédhibitoire. Nous proposons, dans ces travaux, une résolution des équations du modèle à partir de schéma explicite.Ce choix requiert des formulations d’endommagement dynamiques en vitesse d’endommagement et/ou en accélération d’endommagement. Ceci pose également la question de l’intérêt physique de telles formulations. Des effets non négligeablede l’ajout d’une viscosité d’endommagement et d’inertie d’endommagement ont été mis en évidence par rapport à une évolution de l’endommagement gouvernée par une équation elliptique. Ces extensions ont montré des résulats prometteurs dans le contrôle de la vitesse de l’endommagement, mais ont soulevé en parallèle quelques faiblesses notamment des épaississements de “fissure”
Modélisation de l’endommagement et de la fissuration dynamique par une approche à champs de phase, implémenté dans un cadre de résolution temporelle explicite
No full textDynamic fracture a complex phenomenon that remains challenging to predict, posing significant difficulties for industrial applications. Since the early 21st century, numerical approaches have become widely adopted to investigate transient fracture mechanisms. Among these, damage gradient models have gained increasing attention for modeling brittle fracture in both quasi-static and transient regimes. However, these models are predominantly restricted to academic research due to several limitations, one of the most significant being the high computational cost due to both fine mesh requirements and expensive resolution strategies. These present studies propose an alternative resolution strategy in which the model equations are integrated using an explicit time integration scheme. This approach needs the use of timedependent damage formulations, which may be either first- or second-order leading to parabolic or hyperbolic partial differential equation, respectively.Extending the damage formulation to rate dependent model or damage inertia also raises fundamental physical questions about their necessity. The findings of this study demonstrate the influence of incorporating damage viscosity and inertia on both the crack path and crack tip speed, compared to the behaviour predicted by a standard elliptic damage PDE. While these extensions yield promising resultats in capturing dynamic damage evolution, the issue of damage thickening remains a challenge to address.Malgrè les avancées majeures en dynamique de la rupture, ce mécanisme reste une problématique industrielle d’actualité due à son caractére souvent imprévisible. Les méthodes numériques sont des approches de plus en plus déployées pour aider à une meilleure compréhension de ces mécanismes. Les modèles à gradient d’endommagement ont connu un intérêtcroissant pour modéliser la rupture fragile quasistatique et commence à être de plus en plus utiliser pour de la rupture dynamique. Son utilisation reste limiter à l’échelle du laboratoire. Ces modèles requièrent un raffinement de maillagenon négligeable. Couplé à des méthodes de résolution implicite, les coûts de calcul à l’échelle industrielle deviennent rédhibitoire. Nous proposons, dans ces travaux, une résolution des équations du modèle à partir de schéma explicite.Ce choix requiert des formulations d’endommagement dynamiques en vitesse d’endommagement et/ou en accélération d’endommagement. Ceci pose également la question de l’intérêt physique de telles formulations. Des effets non négligeablede l’ajout d’une viscosité d’endommagement et d’inertie d’endommagement ont été mis en évidence par rapport à une évolution de l’endommagement gouvernée par une équation elliptique. Ces extensions ont montré des résulats prometteurs dans le contrôle de la vitesse de l’endommagement, mais ont soulevé en parallèle quelques faiblesses notamment des épaississements de “fissure”
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
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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