1,721,243 research outputs found
Les agents réactifs et le vivant dans une perspective d'évolution coopérative
No full textDominique LESTEL, Benoît GRISON, Alexis DROGOUL : Les agents réactifs et le vivant dans une perspective d'évolution coopérative
Natural evolution is partly understandable with the tools that the researcher has at his own disposal. In that perspective, Distributed Artificial Intelligence introduces extremely flexible procedures that are likely to approach in a completely new way some processes, which were until then neglected or difficult to adress, and to reevaluate their relevance. A transversal similarity between the processes of embryogenesis, hematopoiesis, immunology and social insects' societies sociogenesis could be formalized thanks to its conceptual tools. Such a problematics appears to be particularly relevant for studying and conceptualizing problems situated at the interface between the living and the cognitive, the natural and the artificial.L'évolution naturelle est conceptualisée en partie en fonction des outils accessibles. Dans cette perspective, l'intelligence artificielle distribuée introduit des procédures extrêmement souples qui sont susceptibles d'aborder des processus jusque-là négligés ou difficilement accessibles, et d'en réévaluer la pertinence. Une similarité tranversale entre les processus de l'embryogenèse, de l'immunologie, de l'hématopoïèse et de la sociogenèse dans les colonies d'insectes sociaux est sans doute formalisable avec l'aide des outils conceptuels qu'elle propose. Une telle problématique se révèle particulièrement pertinente pour étudier et conceptualiser les problèmes qui se situent à l'interface du vivant et du cognitif, et à celle du naturel et de l'artificiel.Lestel Dominique, Grison Benoit, Drogoul Alexis. Les agents réactifs et le vivant dans une perspective d'évolution coopérative. In: Intellectica. Revue de l'Association pour la Recherche Cognitive, n°19, 1994/2. Organisation émergente dans les populations : biologie, éthologie, systèmes artificiels. pp. 73-90
Large-scale epidemiological modelling: exploring the impact of the ASEAN economic corridors policy on the Dengue fever epidemic
No full textIn this study, we present an implementation of a hybrid, integrated model that supports various
explorations of the relationship between the increasing regional integration among ASEAN countries
and the Dengue fever epidemic in the same countries. Using the available public data on economic
exchanges, climatic conditions and dengue fever cases as the input, we designed a complex model
composed of three sub-models: a SEIR/SIR mathematical epidemiological model that operates at a local
scale and combines the population dynamics of mosquitoes with the computation of infected mosquitoes
and people, a cellular automata model that provides support for the spread of infected mosquitoes and
people between its cells, an agent-based model based on accurate GIS road data, which reproduces
the traffic of trucks between countries, and an agent-based model of control policy decision-making at
the scale of each country. All these models were coupled within the same framework, supported by
the GAMA modelling and simulation platform (http://gama-platform.org), which scheduled them using
a timescale of 12 hours over 10 years (from 2002 to 2011). This integrated model has been designed
to be completely generic: provided the required data (on climate conditions, dengue cases, commercial
exchanges, and health policies) was available, it could be applied to any geographic location at any
spatial scale. It has been extensively tested on a specific case study: the terrestrial East-West Economic
Corridor, a continuous land route that links Vietnam, Laos, Thailand and Myanmar
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
Automatic revision of knowledge guiding informed search tree exploration : application to the context of geographic data generalisation
No full textCette thèse traite de la révision automatique des connaissances contenues dans les systèmes fonctionnant par exploration informée d'arbres d'états. Ces systèmes, de par leur performance, sont employés dans de nombreux domaines applicatifs. En particulier, des travaux ont proposés d’utiliser cette approche dans le cadre de l'automatisation de la généralisation de données géographiques. La généralisation de données géographique s'intéresse à la dérivation, à partir de données géographiques détaillées, de données moins détaillées adaptées à un besoin particulier (e.g. changement d'échelle). Son automatisation, enjeu majeur pour les agences cartographiques telles que l'Institut Géographique National (IGN), est particulièrement complexe. Les performances des systèmes basés sur l’exploration informée d'arbres d'états sont directement dépendantes de la qualité de leurs connaissances (heuristiques). Or, la définition et la mise à jour de ces dernières s'avèrent généralement fastidieuses. Dans le cadre de cette thèse, nous proposons une approche de révision hors ligne des connaissances basée sur le traçage du système et sur l'analyse de ces traces. Ces traces sont ainsi utilisées par un module de révision qui est chargé d'explorer l'espace des connaissances possibles et d'en modifier en conséquence les connaissances du système. Des outils de diagnostic en ligne de la qualité des connaissances permettent de déterminer quand déclencher le processus de révision hors ligne des connaissances. Pour chaque méthode et approche que nous présentons, une mise en oeuvre est détaillée et expérimentée dans le cadre de l'automatisation de la généralisation de données géographiquesThis work deals with automatic knowledge revision in systems based on an informed tree search strategy. Because of their efficiency, these systems are used in numerous fields. In particular, some literature work uses this approach for the automation of geographic data generalisation. Geographic data generalisation is the process that derives data adapted to specific needs (e.g. map scale) from too detailed geographic data. Its automation, which is a major issue for national mapping agencies like Institut Géographique National (IGN), is particularly complex. The performances of systems based on informed tree search are directly dependant on their knowledge (heuristics) quality. Unfortunately, most of the time, knowledge definition and update are fastidious. In this work, we propose an offline knowledge revision approach based on the system logging and on the analysis of these logs. Thus, the logs are used by a revision module which is in charge of the system knowledge revision by knowledge space exploration. Tools for online knowledge quality diagnosis allow to determine when the offline knowledge process should be activated. For each method and each approach presented, an implementation is proposed in the context of geographic data generalisatio
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
Agent-based visualization
No full textCe mémoire part du constat que la visualisation est le parent pauvre de l'approche de modélisation à base d'agents: peu citée, peu mise en avant, elle constitue néanmoins, pour beaucoup de modélisateurs, non seulement leur premier point d'entrée vers la construction de modèles, mais aussi une façon de plus en plus prégnante, de concevoir, vérifier, voire valider des modèles de systèmes complexes. Le domaine de la modélisation à base d'agents, longtemps peu structuré, est en train de progressivement s'organiser en termes de méthodologies de conception, de communication, de description. Le succès du protocole ODD est là pour en témoigner: face à des demandes de représentation de systèmes de plus en plus complexes, les modélisateurs ont besoin de mettre de l'ordre dans leurs façons de modéliser et ils y parviennent. Cependant, il est étonnant de constater qu'aucune place n'est réservée dans ODD, ni dans aucune autre méthodologie approchante, à la façon de visualiser le modèle décrit ou à concevoir. Pour beaucoup de théoriciens de la modélisation, cette étape n'existe tout simplement pas, ou, si elle existe, est considérée comme le lointain produit dérivé d'un modèle déjà conçu, vérifié et validé. Pourtant, l'étude des pratiques de la modélisation à base d'agents révèle tout le contraire: l'aller-retour entre l'écriture et la visualisation d'un modèle fait partie intégrante du quotidien de nombreux chercheurs, comme en témoigne le succès de la plate-forme NetLogo. Cette visualisation, partie d'une démarche intégrée, permet de façon intuitive de vérifier et raffiner aussi bien les comportements individuels des agents que les structures collectives ou émergentes attendues. Poussée à l'extrême, cette pratique se rencontre aussi dans les démarches de modélisation et/ou simulation participative, où la visualisation du modèle sert de médiation entre acteurs et de support aux tâches, collectives, de modélisation. Absente des propositions méthodologiques, la visualisation de modèles à base d'agents se retrouve donc essentiellement délimitée et structurée par des pratiques individuelles, parfois partagées sous la forme de préceptes , mais rarement généralisables au-delà de la conception d'un modèle. Il existe pourtant des façons de visualiser, des manières de chercher à faire ressortir une information spécifique, des méthodes à suivre pour étudier visuellement une abstraction…Information visualization is the study of interactive visual representations of abstract data to reinforce human cognition. It is very closely associated with data mining issues which allow to explore, understand and analyze phenomena, systems or data masses whose complexity continues to grow today. However, most existing visualization techniques are not suited to the exploration and understanding of datasets that consist of a large number of individual data from heterogeneous sources that share many properties with what are commonly called "complex systems". The reason is often the use of monolithic and centralized approaches. This situation is reminiscent of the modeling of complex systems (social sciences, chemistry, ecology, and many other fields) before progress represented by the generalization of agent-based approaches twenty years ago. In this thesis, I defend the idea that the same approach can be applied with the same success to the field of information visualization. By starting from the now commonly accepted idea that the agent-based models offer appropriate representations the complexity of a real system, I propose to use an approach based on the definition of agent-based visualization models to facilitate visual representation of complex data and to provide innovative support which allows to explore, programmatically and visually, their underlying dynamics. Just like their software counterparts, agent-based visualization models are composed of autonomous graphical entities that can interact and organize themselves, learn from the data they process and as a result adapt their behavior and visual representations. By providing a user the ability to describe visualization tasks in this form, my goal is to allow them to benefit from the flexibility, modularity and adaptability inherent in agent-based approaches. These concepts have been implemented and experimented on the GAMA modeling and simulation platform in which I developed a 3D immersive environment offering the user different point of views and way to interact with agents. Their implementation is validated on models chosen for their properties, supports a linear progression in terms of complexity, allowing us to highlight the concepts of flexibility, modularity and adaptability. Finally, I demonstrate through the particular case of data visualization, how my approach allows, in real time, to represent, to clarify, or even discover their dynamics and how that progress in terms of visualization can contributing,in turn, to improve the modeling of complex systems
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