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Mesures de contraintes résiduelles dans des pièces épaisses par la méthode du trou profond
No full textInternational audienceMesures de contraintes résiduelles dans des pièces épaisses par la méthode du trou profon
Etude de composites transparents pour protection balistique
No full textInternational audienceEtude de composites transparents pour protection balistiqu
Cache Less to Save More: A Cost-Based Distributed Caching Strategy for ICN
No full textInternational audienceThe rapid growth of global data traffic has exposed limitations in traditional content delivery architectures. Information-Centric Networking (ICN) addresses these challenges by leveraging in-network caching to enhance scalability, reduce latency, and improve overall performance. However, existing caching strategies either optimize single-node cache management without considering network-wide costs, or address distribution without hardware-aware cost modeling. We propose a unified, cost-aware distributed caching strategy that integrates multi-tier caching at each node with network-wide replication, guided by a comprehensive cost model including resource depreciation, bandwidth, energy, and Service Level Agreement compliance. Our approach minimizes redundant replication on the network while maximizing cache hit rates and reducing latency. Experimentsshow on average 19.15%, and up to 45.19%, cost reduction, 8.11%, and up to 32.15%, cache hit ratio increase, and 9.01%, and up to 27.21%, latency improvement over other methods, offering a cost-effective solution for next-generation ICN systems
Ellipsoid Tether Model for Collision Avoidance in a Fleet of ROVs - Summary and Extension
No full textInternational audienceDuring its navigation, the tether of Remote Operated Vehicle (ROV) is subject to entanglement with obstacles or other ROVs' tethers. This specificity means that the classic literature on multi-robot collision avoidance is not suitable for tethered multi-robot scenarios. Thus, we propose a guarantee ellipsoid model of the ROV's tether and its obstacles to perform a collision avoidance method, adapted for a fleet of ROVs and low in calculation. The model guarantees that if an obstacle is not inside or partially inside the ellipsoid model, then the risk of collision is exclude. The only information required for using this model is the position of the two attachment points and the tether length. A collision avoidance strategy has been developed based on potential field methods, bypass paths and the management of the distance between the two attachment points. Simulations show the effectiveness of the method with several scenarios. The limits of the method are discussed
PhysioFormer: A Spatio-Temporal Transformer for Physical Rehabilitation Assessment
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Exploitation scientifique de CentipedeRTK
No full textInternational audienceDéveloppé depuis 2019, le réseau CentipedeRTK est un réseau GNSS collaboratif permanent dont l’objectif principal est de rendre le positionnement RTK librement accessible, principalement à l’aide de récepteurs et d’antennes à bas coût. Depuis sa création, le réseau s’est considérablement développé, bien au-delà des frontières de la France, et compte aujourd’hui près de 900 stations. Il est utilisé par de nombreux utilisateurs. Le principal secteur d’utilisation est l’agriculture, mais de plus en plus d’organismes publics et privés ainsi que des particuliers y ont recours.La communauté des géosciences s’est rapidement intéressée au réseau, d’abord comme utilisatrice de ces bases RTK (suivi du niveau de la mer, relevés par drone, etc.), puis pour le post-traitement des mesures brutes issues de ces bases. Ainsi, les données des stations permanentes du réseau CentipedeRTK sont archivées quotidiennement depuis la mi-2022 par le centre de données du RENAG, dans le but de les exploiter pour des applications en géosciences.Nous présentons ici les résultats de deux études récentes menées à partir des données acquises en 2023 par un sous-réseau de plus de 250 stations CentipedeRTK localisées en France métropolitaine. Les observations ont été analysées en mode PPP à l’aide du logiciel GipsyX. Les positions ainsi déterminées ont été évaluées par comparaison avec celles issues de stations appartenant à des réseaux conventionnels (RGP, RENAG, Orphéon). L’analyse des séries temporelles montre une bonne qualité globale, malgré une légère dégradation des répétabilités, particulièrement marquée sur la composante verticale. Les retards troposphériques estimés pour ce sous-réseau ont été comparés à ceux obtenus à partir des stations conventionnelles. Le niveau d’accord est très satisfaisant, bien qu’un biais subsiste, vraisemblablement lié aux limites des antennes low-cost (sensibilité au trajet multiple, absence de calibration précise).Ces résultats soulignent la nécessité de mieux caractériser et corriger les défauts liés aux antennes low-cost, mais aussi d’informer et d’accompagner la communauté CentipedeRTK dans l’adoption de bonnes pratiques d’installation des stations (documentation, recommandations techniques, etc.)
Offline and Online Use of Interval and Set-Based Approaches for Control and State Estimation : A Selection of Methodological Approaches and Their Application
No full textInternational audienceControl and state estimation procedures need to be robust against imprecisely known parameters, uncertainty in initial conditions, and external disturbances. Interval methods and other set-based techniques form the basis for the implementation of powerful approaches that can be used to identify parameters of dynamic system models in the presence of the aforementioned types of uncertainty. Moreover, they are applicable to a verified feasibility and stability analysis of controllers and state estimators. In addition to these approaches which are typically used offline for analysis of system models designed with classical floating point procedures, interval and set-based methods have also been developed in recent years, which allow to directly solve the associated design tasks and to implement reliable techniques that are applicable online, i.e., during system operation. The latter approaches include set-based model predictive control, online parameter adaptation techniques for nonlinear variable-structure and backstepping controllers, interval observers, and fault diagnosis techniques. This paper provides an overview of the methodological background and reviews numerous practical applications for which interval and other set-valued approaches have been employed successfully
Earth-Space Illiteracy, Cultivated Dyslexia, and Moralized Agnosia: Exploring the Grammar of Contemporary Sustainability Governance
No full textInternational audienceContemporary sustainability governance—particularly with respect to democratic engagement—is crippled by a triad of cognitive failures. Earth-Space Illiteracy denotes a basic lack of vocabulary and understanding of the physical and ethical interdependencies between our planet and the near-space environment. This is exacerbated by a Cultivated Dyslexia, a historically conditioned linguistic tendency within Western thought resulting in the treatment of Earth and Heaven as a rigid binary, hindering the development of Earth-Space inference patterns. Within contemporary philosophy, these latent biases have culminated in a Moralized Agnosia, an actively produced ignorance exaggerated by speculative theories which legitimize the disregard of critical facts about our orbital environment in the name of a narrowed, planet-turned attention. Unlearning these self-incurred learning disabilities is critical for acquiring a more extensive and conceptually adequate vocabulary to address the challenges that the New Space economy and the militarization of outer space pose to the sustainability of the Earth-Space commons. Drawing on perfectionist theories of education and Stanley Cavell’s vision of philosophy as the “education of grownups,” this intervention suggests that in our post-planetary era in which orbital debris and a crowded nightscape are becoming ever more salient collective problems, we must be ready to question the fixed terms and ideas that structure our understanding of ecological praxis, developing new critical languages and increasing our Earth-Space literacy
Political Granularities: On the Utopia of Planetary Computation and the Alienation of Responsibility
No full textInternational audienceThis talk, delivered in the framework of the ongoing workshop Le souple, le dur, et le weird, presented a meta-critique of the planetary project being presented by authors such as Benjamin Bratton. It argued that the essence of the current desire for planetary computation is a total liberation from the constraints of self-conscious responsibility which were developed alongside the production of the modern subject. Further developing the dytopian means of removing subjectivity, it proposed to think through the shape of education within a world liberated from the burden of producing responsible subjects, suggesting that this was in a sense the ideal being promoted by planetary futurism