Fast Dynamics of a three dimensional eel-like robot: comparisons with Navier-Stokes simulations

International audienceThis article proposes a dynamic model of the swim of elongated ﰣshes suited to the on-line control of bio-mimetic eel-like robots. The approach is analytic and can be considered as an extension of the original reactive "Large-Elongated-Body-Theory" of Lighthill to the three dimensional self propulsion augmented of a resistive empirical model. While all the mathematical fundamentals are detailed in [1], this article essentially focuses on the numerical validation and calibration of the model and the study of swimming gaits. The proposed model is coupled to an algorithm allowing us to compute the motion of the ﰣsh head and the ﰣeld of internal control torque from the knowledge of the imposed internal strain ﰣelds. Based on the Newton-Euler formalism of robots dynamics, this algorithm works faster than real time. As far as precision is concerned, many tests obtained with several planar and three dimensional gaits are reported and compared (in the planar case) with a Navier-Stokes solver, devoted until today to the planar swim. The comparisons obtained are very encouraging since in all the cases we tested, the diﰢerences between our simpliﰣed and reference simulations do not exceed ten per cent

Diagnostic value of minor salivary glands biopsy for the detection of Lewy pathology

The recent demonstration of the presence of Lewy pathology in the submandibular glands of Parkinson\u27s disease (PD) patients prompted us to evaluate the diagnostic performance of minor salivary gland biopsy for PD. Minor salivary glands were examined for Lewy pathology using phosphorylated alpha-synuclein antibody in 16 patients with clinically diagnosed PD and 11 control subjects with other neurological disorders. Abnormal accumulation of alpha-synuclein was found in 3 out of 16 PD patients. Two control subjects exhibited weak phosphorylated alpha-synuclein immunoreactivity. Our results do not support the use of minor salivary glands biopsy for the detection of Lewy pathology in living subjects

Numerical methods for RANSE simulations of a self-propelled fish-like body

International audienceThis paper deals with numerical simulations on a self-propelled fish-like body. Firstly, the methods used to achieve such simulations based on the solution of the Reynolds-Averaged-Navier–Stokes Equations are described: resolution of the Newton's law (parameterization, use of a description of the rotation based on a quaternion), regridding strategies linked to body motion and deformation, fluid–motion coupling methods. In the second part, realistic applications are shown. The interaction between the fluid and the body is fully solved since the evolution of the body's position is not imposed but computed. Only the imposed deformation of the shape and its interaction with the fluid produce forces on the body and, consequently, motion

: Rapport final du projet ANR 2006-2008 (annexes scientifiques)

As a 24 months platform project, Lutin Game Lab was designed for making academic researchers and game companies cooperate in order to reach a new stage in the process of game quality assessment, before and after they are available on the market. The project was organized along 6 WP, all of them having fulfilled their specific goals, although we had to endure some delays due to the time required for settling the technical platform and due to the lack of time available for the companies to collaborate during the year 2008.The project results can be summed up in 4 different aspects:* A platform is now open to companies as well as to academic labs, equipped with all the devices and the softwares needed for conducting evaluation of gamers behaviour, including all game platforms, excepted for on-line games. Two eye-tracking devices and sensorial analysis tools are part of the equipment of the platform. This technical platform is operated by the UMS CNRS Lutin at the Cité des Sciences in Paris.* The methods created for analyzing the existing games and the ones in development phase were scientifically validated and adapted to the requirements of companies (time needed, display of the results, prerequisites and modes of cooperation with developers). These methods have not yet been tested in the developing phase of real games except for one of them (QRC), due to the workload of developers during this period. * The methods are the following:o Artificial expert for the prediction of gamers judgments based on a description framework of game properties. A subjective evaluation database has been designed using the data collected during the tests of 240 gamers (experts and naives) expressing judgments in a 11 items questionnaire, using the data from an objective description of game properties and the data obtained through an "objectivated subjective" description of games qualities retrieved from experts who designed and filled up a framework of 56 items per game genre (126 iterations). This expert allows companies to test their games while they are still in the design phase through the description framework in order to predict the judgments from the gamers and to optimize their various choices in game design using the 15 fuzzy models selected for each game genre.o Usability testing method adapted specifically to videogames (Quick Reality Check, QRC), based on a test protocol involving 10 gamers, on logs tracking the gamer behaviour (implemented by the developers in their prototype), on synthetic visualization tools displaying the results, and on remediation method in cooperation with game designers (game doctor). This method focuses on ergonomics features and acceptability issues.o An eyetracking method dedicated to gamers behaviour analysis. It helps to explore in-depth the areas or phases of concern discovered with the previous method. This allows the game designers to reshape some features in the interfaces and to compare their results with the patterns of each game genre that the research was able to modelize.o A method for tracking emotional states during the game, through sensors placed on the gamers bodies, in order to explore and better understand the reasons of the problems pointed out by the other methods. This is a much more innovative methodology and field of research and this explains the need for focusing on specific features in order to validate the whole framework with the existing scientific state of the art. This is a very promising field and a very attractive one for the game designers, one that would require much more research efforts.o An artificial expert providing diagnosis through the gathering of every piece of data collected during the various tests, with added results from on line questionnaires. The expert software provides an integrative view of the results for a specific game and can refer it to the various models available in the literature.* In the gameplay evaluation field, the project evolves from a review of literature to the design of a wiki open to the community of game designers, which aim is to create de knowledge database about gameplay qualities for each game genre. The wiki includes a list of rules shared by the community and examples of games displaying the uses of these rules, extracted from a corpus of the most famous games. The database can be enriched with new cases, rules can be adapted, through the revision process of the wiki which includes collective validation. Developers can access the wiki as a resource for validation of their choices.In brief, the platform offers a set of devices, a set of methods, available for the game industry, operated by Lutin experts, and a website including the wiki. Lutin Game lab platform represents an European reference center in the field of game evaluation. Lutin plans to design a quality label for games that could be used before the games are placed on the market. LUtin Game Lab requires a new research project devoted to the extension of the methods to on-line games (Lutin Game Lab on line). The next year will be devoted to dissemination and validation on real game being developed.Le projet annonçait ainsi ses objectifs en 2006 : " Lutin Game Lab, projet de plate-forme de 24 mois, se propose de fédérer les forces de recherche académiques et de développement des entreprises pour faire faire un pas significatif aux méthodologies d'évaluation de la qualité d'un jeu vidéo fini ou en cours de développement. " Le travail a comporté 6 sous -projets qui ont tous été menés à bien conformément au programme prévu avec des décalages non négligeables dus notamment au temps nécessaire au montage technique de la plate-forme et à la difficulté des entreprises à dégager du temps pour leur collaboration au moment voulu alors qu'elles sont sous haute pression concurrentielle. Le bilan du projet peut se résumer en 4 points : * il existe désormais en France une plate-forme ouverte aux entreprises et aux laboratoires, équipée de tous les matériels et logiciels nécessaires pour faire l'évaluation des comportements des joueurs de jeux vidéo, toutes plates-formes de jeu confondus, à l'exception des jeux multi joueurs en ligne. Cette plate-forme technique, comportant notamment des dispositifs d'oculométrie opérationnels de divers types, et des dispositifs d'analyse sensorielle, est opérationnelle en permanence dans le cadre des missions de l'UMS CNRS Lutin 2803 à la Cité des Sciences. * Les méthodes élaborées pour l'analyse des jeux existants et des jeux en cours de développement ont été validées scientifiquement et opérationnellement selon les critères des entreprises de jeux vidéo (délais, présentation des résultats, prérequis et formes de coopération). Ces méthodes devront cependant être validées en situation de jeux en cours de développement car les délais de coopération avec les entreprises n'ont permis de mettre en œuvre cette étape que pour une seule de ces méthodes (dite QRC)* Les méthodes comportent 5 volets : o un expert artificiel prédictif qui permet de prédire l'appréciation subjective des joueurs à partir d'une description formalisée des propriétés d'un jeu. Une base de données d'évaluation subjective a été constituée à partir de tests réalisés par 240 joueurs de tous niveaux et de leur appréciation subjective (11 items), à partir de description des propriétés objectives du jeu (106 items) et à partir d'une description subjective objectivée des qualités d'un jeu par genre (56 items par genre de jeu) et de 126 itérations de cette grille réalisée à partir d'une extraction d'expertise auprès de game designers et élèves game designers. Il est proposé aux entreprises de jeux vidéo de tester leur jeu dans une phase amont du développement pour prédire les scores de leurs jeux et ensuite optimiser les choix effectués, en exploitant les 15 modèles en logique floue sélectionnés pour chaque genre de jeu. o Une méthode en usability (Quick Reality Check) qui comporte un protocole de tests auprès de 10 joueurs minimum, des outils de suivi des déplacements par implantation de logs dans le jeu en cours de développement, de modes de visualisation synthétique des résultats et une méthode de correction associant les développeurs (Game Doctor). Cette méthode traite avant tout les questions d'ergonomie et d'acceptabilité. o Une méthode de suivi du regard des joueurs permettant d'affiner les résultats de la méthode précédente, sur des zones ou des phases problématiques pour repositionner le game design et l'ergonomie en fonction des patterns, ou signatures, identifiés par la recherche pour chaque type de jeux. o Une méthode de suivi de l'engagement émotionnel durant le jeu à partir de capteurs d'analyse sensorielle placés sur les joueurs, permettant là aussi d'affiner la recherche éventuelle de problèmes pour des phases plus précises selon les stratégies du game designer. Cette méthode est la plus innovante en termes de recherche et nos résultats restent donc limités à certains points précis qui sont cependant très prometteurs et nécessiteraient des travaux supplémentaires.o Un expert artificiel diagnostic permettant de traiter et de synthétiser toutes les données recueillies lors des tests des autres méthodes, de les compléter par des questionnaires en ligne si nécessaire et de les rapporter à des modèles issus de la littérature pour proposer un diagnostic intégré sur les qualités d'un jeu donné. * Dans le domaine du gameplay, le projet a évolué à partir d'un recensement exhaustif de la littérature sur la mise en place d'un wiki permettant à toute la communauté des développeurs de constituer une base de connaissances partagées sur les qualités du gameplay selon les genres. Ce wiki comporte un énoncé de règles reconnues par la communauté mais aussi leur exemplification à partir d'un corpus de jeux parmi les plus connus dans tous les genres. La base peut être enrichie par d'autres études de cas, les règles peuvent être affinées, et les développeurs peuvent la consulter en tant que de besoin pour valider les choix qu'ils effectuent. La mise en place de la plate-forme comporte ainsi une partie d'équipements localisés à la cité des sciences, une expertise en méthodes, directement opérationnelles et proposées déjà aux entreprises par les différents partenaires membres de Lutin, et un site collaboratif qui rassemble la communauté autour de son expertise propre. Lutin Game Lab peut ainsi prétendre devenir un centre de références européen en termes de méthodes qualité pour les jeux vidéo et nous prévoyons de travailler à proposer un label pour qualifier les jeux vidéo avant leur mise sur le marché, ainsi qu'à une extension de ses compétences pour les jeux vidéo multi joueurs en ligne (Lutin Game Lab on line). Le projet a ainsi atteint son objectif général ainsi que ses objectifs particuliers, à l'exception du temps de validation encore nécessaire auprès des entreprises qui n'a pu être pris en compte durant le projet

A idealização da alteridade: reflexões sobre seus fundamentos na história ocidental

Así como fueron considerados “salvajes” o “atrasados”, los nativos de las tierras colonizadas por los europeos también han sido objeto de elogios que han llegado hasta la idealización, y que han surgido especialmente entre las élites intelectuales de origen europeo. Este último tipo de discursos e imaginarios, relativamente poco comunes y escasamente estudiados, parece contraponerse al racismo e invitaría a una valoración de la diversidad cultural. Sin embargo, este artículo tiene como objetivo plantear un análisis crítico de dicho elogio de la alteridad, el cual, contrariamente a lo que se suele creer, no es un avance intelectual reciente, sino un discurso basado en antiguos mitos premodernos. Para alcanzar este objetivo, se hizo un análisis hermenéutico de los discursos de autores y colectivos reconocidos en Occidente, quienes han recurrido a términos connotados positivamente para describir las culturas de pueblos no europeos. En esos discursos se observaron algunos patrones generales, lo cual permitió relacionarlos con estructuras míticas de larga duración, tales como el mito cristiano del Jardín del Edén y el mito grecolatino de una Edad de Oro. Como una prolongación de esto, hoy se puede considerar al Otro “natural” y “tradicional” como el ejemplo de un ser humano admirable. No obstante, en este artículo se concluye que ese tipo de representaciones, aunque hoy estimadas como políticamente correctas, se basan en versiones esencializadas de la alteridad, las cuales en realidad reproducen ideales hegemónicos y contribuyen a ocultar la complejidad de la diversidad cultural.Just as the natives of lands colonized by Europeans were considered "wild" or "slow," they have also been the object of praise that has gone as far as idealization, and that have emerged especially among the intellectual elites of European origin. This last type of discourses and imaginaries, relatively rare and scarcely studied, seems to be opposed to racism and would invite an appreciation of cultural diversity. However, this article aims to propose a critical analysis of this praise of alterity, which, contrary to what is usually believed, is not a recent intellectual advance, but a discourse based on ancient pre-modern myths. To achieve this goal, a hermeneutic analysis of the discourses of authors and collectives recognized in the West, who have resorted to positively connoted terms to describe the cultures of non-European peoples was made. In these discourses, some general patterns were observed, which allowed them to be related to mythical structures of long duration, such as the Christian myth of the Garden of Eden and the Greek-Latin myth of a Golden Age. As an extension of this, today we can consider the Other "natural" and "traditional" as the example of an admirable human being. However, in this article it is concluded that such representations, although nowadays considered as politically correct, are based on specialized versions of alterity, which in reality reproduce hegemonic ideals and contribute to hide the complexity of the cultural diversity.Assim como foram considerados “selvagens” ou “atrasados” os nativos das terras colonizadas pelos europeus, também foram objeto de elogios que chegaram até a idealização e que surgiram especialmente entre as elites intelectuais de origem europeia. Este último tipo de discursos e imaginários, relativamente pouco comuns e escassamente estudados, parece contrapor-se ao racismo e convida a uma valorização da diversidade cultural. Contudo, este artigo tem como objetivo propor uma análise crítica do elogio da alteridade, o qual, ao contrário do que se costuma acreditar, não é um avanço intelectual recente, mas sim um discurso baseado em antigos mitos pré-modernos. Para atingir esse objetivo, fez-se uma análise hermenêutica dos discursos de autores e coletivos reconhecidos no Ocidente, os que têm recorrido a termos conotados positivamente para descrever as culturas de povos não europeus. Nesses discursos, foram observados alguns padrões gerais, o que permitiu relacioná-los com estruturas míticas de longa duração, tais como o mito cristão do Jardim do Éden e o mito greco-latino de uma Idade do Ouro. Como uma prolongação disso, hoje pode-se considerar o Outro “natural” e “tradicional” como o exemplo de um ser humano admirável. No entanto, neste artigo, conclui-se que esse tipo de representações, embora hoje estimadas como politicamente corretas, estão baseadas em versões essencializadas da alteridade, as quais, em realidade, produzem ideais hegemônicos e contribuem para ocultar a complexidade da diversidade cultural.https://revistas.udem.edu.co/index.php/anagramas/article/view/191

Optimization of a Synthetic Jet Actuator for Aerodynamic Stall Control

International audienceThe numerical simulation of aerodynamic stall control using a synthetic jet actuator is presented and the automatic optimization of the control parameters is investigated. Unsteady Reynolds-averaged Navier-Stokes equations are solved on unstructured grids using a near-wall low-Reynolds number turbulence closure to simulate the effects of a synthetic jet, located at 12% of the chord from the leading edge of a NACA 0015 airfoil, for a Reynolds number Re = 8.96 10 5 and incidences between 12 to 24 degrees. Then, an automatic optimization procedure coupled with the flow solver is employed to optimize the parameters of the actuator (momentum coefficient, frequency, angle with respect to the wall) at each incidence in order to increase the time-averaged lift. A significant increase of the maximum lift is obtained (+52% with respect to the baseline airfoil) and the stall delayed from 16 • to 22 • for optimal parameters. The flow characteristics and the influence of the respective control parameters are analysed

Adaptive mesh strategy applied to turbulent flows

International audienc

Simulation and Optimization of Stall Control for an Airfoil with a Synthetic Jet

International audienceThis study concerns the simulation and optimization of stall control, using a synthetic jet. The flow is simulated by solving unsteady Reynolds-averaged Navier-Stokes equations with a near-wall low-Reynolds number turbulence closure. The flow around a NACA 0015 airfoil, including a synthetic jet located at 12% of the chord, is studied for a Reynolds number Re = 8.96 10 5 and for angles of attack from 12 to 24 degrees. The optimization of the control parameters (momentum coefficient, frequency, angle w.r.t. the wall) is intended, by coupling an automatic optimization algorithm with the flow solver. A significant improvement of the control efficiency is obtained (maximum lift increased of 34% and stall delayed from 19 • to 22 • w.r.t. the initial controlled flow). A Physical analysis of the flow is performed to characterize the optimal control process found

Raffinement automatique de maillage pour la simulation des écoulements à surface libre

Nous présenterons une méthode de raffinement automatique de maillage pour la simulation des écoulements visqueux incompressibles, en calcul parallèle, sur des maillages non-structurés. La méthode est appliquée aux écoulements à surface libre stationnaires et non-stationnaires. Pour ces simulations, une forte augmentation de la qualité des solutions est obtenue

CFD Simulation of PMM Motion in Shallow Water for the DTC Container Ship

International audienceThis paper is devoted to the validation exercises with the ISIS-CFD code conducted for the test cases proposed for the MASHCON conference. CFD simulations have been performed for the 4 different pure yaw and pure sway test cases under shallow water condition. Predicted results are compared with the measurement data provided by FHR