1,720,958 research outputs found
Conception de matériaux à bandes interdites inspirée par la morphogenèse
No full textIn this work, we propose a novel generative technique for designing materials with correlated disorder, inspired by Alan Turing’s morphogenesis theory on the structuring of living organisms. Unlike conventional methods that rely on optimization techniques such as gradient descent or stochastic algorithms, our approach is based on simple local interactions that guide the self-organization of the generated patterns. By removing the need to minimize a cost function and decentralizing design constraints, this technique becomes inherently scalable for creating large domains with precise control over disorder. As a validation, it facilitated the generation of self-organized hyperuniform disordered materials exhibiting isotropic electromagnetic band gaps. These structures were exploited to design freeform waveguides that demonstrate excellent transmission performances without requiring the optimization processes typically needed for conventional periodic crystals. This method thus offers promising prospects for automating the design of large-scale devices involved in a wide range of applications.Dans ce travail, nous proposons une nouvelle technique générative pour la conception de matériaux à désordre corrélé, inspirée par la théorie de la morphogenèse d’Alan Turing sur la structuration des organismes vivants. Contrairement aux méthodes conventionnelles qui s’appuient sur des techniques d’optimisation telles que la descente de gradient ou les algorithmes stochastiques, notre approche repose sur des interactions locales simples guidant l’auto-organisation des motifs générés. En éliminant la nécessité de minimiser une fonction de coût et en décentralisant les contraintes de conception, cette technique devient intrinsèquement évolutive pour la création de grands domaines avec un contrôle précis du désordre. À titre de validation, elle a permis la génération de matériaux désordonnés hyperuniformes auto-organisés présentant des bandes interdites électromagnétiques isotropes. Ces structures ont été exploitées pour concevoir des guides d’onde de formes libres, démontrant d’excellentes performances en transmission sans nécessiter les processus d’optimisation typiquement requis pour les cristaux périodiques conventionnels. Cette méthode offre ainsi des perspectives prometteuses pour l’automatisation de la conception de dispositifs de grandes dimensions intervenant dans une large gamme d’applications
Conception de matériaux à bandes interdites inspirée par la morphogenèse
No full textIn this work, we propose a novel generative technique for designing materials with correlated disorder, inspired by Alan Turing’s morphogenesis theory on the structuring of living organisms. Unlike conventional methods that rely on optimization techniques such as gradient descent or stochastic algorithms, our approach is based on simple local interactions that guide the self-organization of the generated patterns. By removing the need to minimize a cost function and decentralizing design constraints, this technique becomes inherently scalable for creating large domains with precise control over disorder. As a validation, it facilitated the generation of self-organized hyperuniform disordered materials exhibiting isotropic electromagnetic band gaps. These structures were exploited to design freeform waveguides that demonstrate excellent transmission performances without requiring the optimization processes typically needed for conventional periodic crystals. This method thus offers promising prospects for automating the design of large-scale devices involved in a wide range of applications.Dans ce travail, nous proposons une nouvelle technique générative pour la conception de matériaux à désordre corrélé, inspirée par la théorie de la morphogenèse d’Alan Turing sur la structuration des organismes vivants. Contrairement aux méthodes conventionnelles qui s’appuient sur des techniques d’optimisation telles que la descente de gradient ou les algorithmes stochastiques, notre approche repose sur des interactions locales simples guidant l’auto-organisation des motifs générés. En éliminant la nécessité de minimiser une fonction de coût et en décentralisant les contraintes de conception, cette technique devient intrinsèquement évolutive pour la création de grands domaines avec un contrôle précis du désordre. À titre de validation, elle a permis la génération de matériaux désordonnés hyperuniformes auto-organisés présentant des bandes interdites électromagnétiques isotropes. Ces structures ont été exploitées pour concevoir des guides d’onde de formes libres, démontrant d’excellentes performances en transmission sans nécessiter les processus d’optimisation typiquement requis pour les cristaux périodiques conventionnels. Cette méthode offre ainsi des perspectives prometteuses pour l’automatisation de la conception de dispositifs de grandes dimensions intervenant dans une large gamme d’applications
Etude de guides d'onde sublongueur d'onde en forme de" C " pour la conception de nano-coupleurs optiques
No full text32 f. : ill. ; 30cm+(CD-ROM)Dans ce travail, nous nous sommes intéressés à la conception d'un nano-coupleur optique conique constitué de guides d'onde en forme de "C". Une étude préliminaire 2D de l'effet des paramètres géométriques sur la longueur d'onde de coupure du mode fondamental TE10 de la cavité en forme de "C" en argent a été réalisée par la méthode FDTD. Dans un second temps, les conditions nécessaires pour l'obtention d'un couplage à 2D entre deux guides d'onde ont été déterminées. Enfin, des calculs FDTD à 3D de transmission et de confinement ont été menés en faisant varier le nombre et la hauteur des guides constituant le coupleur. Les résultats de ces simulations ont montré la possibilité de guider et de confiner la lumière par le biais de ces coupleurs
Design of bandgap materials inspired by morphogenesis
No full textDans ce travail, nous proposons une nouvelle technique générative pour la conception de matériaux à désordre corrélé, inspirée par la théorie de la morphogenèse d’Alan Turing sur la structuration des organismes vivants. Contrairement aux méthodes conventionnelles qui s’appuient sur des techniques d’optimisation telles que la descente de gradient ou les algorithmes stochastiques, notre approche repose sur des interactions locales simples guidant l’auto-organisation des motifs générés. En éliminant la nécessité de minimiser une fonction de coût et en décentralisant les contraintes de conception, cette technique devient intrinsèquement évolutive pour la création de grands domaines avec un contrôle précis du désordre. À titre de validation, elle a permis la génération de matériaux désordonnés hyperuniformes auto-organisés présentant des bandes interdites électromagnétiques isotropes. Ces structures ont été exploitées pour concevoir des guides d’onde de formes libres, démontrant d’excellentes performances en transmission sans nécessiter les processus d’optimisation typiquement requis pour les cristaux périodiques conventionnels. Cette méthode offre ainsi des perspectives prometteuses pour l’automatisation de la conception de dispositifs de grandes dimensions intervenant dans une large gamme d’applications.In this work, we propose a novel generative technique for designing materials with correlated disorder, inspired by Alan Turing’s morphogenesis theory on the structuring of living organisms. Unlike conventional methods that rely on optimization techniques such as gradient descent or stochastic algorithms, our approach is based on simple local interactions that guide the self-organization of the generated patterns. By removing the need to minimize a cost function and decentralizing design constraints, this technique becomes inherently scalable for creating large domains with precise control over disorder. As a validation, it facilitated the generation of self-organized hyperuniform disordered materials exhibiting isotropic electromagnetic band gaps. These structures were exploited to design freeform waveguides that demonstrate excellent transmission performances without requiring the optimization processes typically needed for conventional periodic crystals. This method thus offers promising prospects for automating the design of large-scale devices involved in a wide range of applications
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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
- …
