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Leveraging Digital Twins and AI for Enhanced Gearbox Condition Monitoring in Wind Turbines: A Review
No full textInternational audienceWind power plays a significant role in sustainable energy production, but the reliability of wind turbines depends heavily on the integrity of their gearboxes. Gearbox failures can lead to significant downtime and operational disruption. In this context, this paper provides an overview of the evolution of gearbox monitoring techniques, culminating in the emergence of digital twin (DT) technology. We explore the application of DT technology to gearbox condition monitoring, focusing on two critical components: bearings and gears. This includes a comprehensive review of methodologies involving model-based approaches and data-driven techniques using signal processing (SP) and artificial intelligence (AI) algorithms. We address the challenges of “learning with minimal knowledge” and propose a framework for the effective application of DT technology. Finally, we discuss future research directions and potential contributions to advancing the field of gearbox condition monitoring through the continued development and implementation of DT-based solutions
Impact of Zero-Valent Iron Nanoparticles and Polyethylene Microplastics, Individually or in Combination, on Oxidative Stress in Marine Microalga Isochrysis Galbana Affinis Tahiti
No full textThe cross effects of zero-valent iron nanoparticles (nZVI) and polyethylene microplastics (PE) have raised little attention though they address many health concerns due to their concomitant presence in aquatic environments. Actually, the induced-potential ecotoxicological effects on biota remain poorly understood. This study aims to explore the toxicity mechanisms of nZVI, either alone or in combination with PE, on a model marine microalga, Isochrysis galbana affinis tahiti (T. isochrysis). The effects on growth rate, photosynthetic pigments, biochemical composition and oxidative status of T. isochrysis under both conditions were investigated. To this end, the microalgae were exposed for 72 hours to increasing concentrations of nZVI (ranging from 5 to 400 µg. L-1) without or with PE at 25 mg. L-1. The results showed that the nZVI/PE co-exposure in natural seawater, led to a significant increase in algal growth compared to single nZVI exposure. Additionally, a notable change in photosynthetic activity and biomolecular composition (proteins and exopolysaccharides) was observed at the highest concentrations. All the oxidative stress biomarkers that were examined (H2O2, MDA and antioxidant enzymes) demonstrated that the stress increased significantly with the nZVI concentration and slightly in the presence of PE. Furthermore, the presence of PE attenuates the measured oxidative stress induced by nZVI. This comparative study provides important insights into the risks posed by the combined exposure of iron nanoparticles and polyethylene in aquatic ecosystems
De la jeunesse aux Amériques. Politisations, altérités, cultures (XXe - XXIe siècles)
No full textInternational audienceLa jeunesse n'est-elle qu'un mot ? C'est à la célèbre réflexion de Pierre Bourdieu que répond ce livre, en ancrant sa réflexion en terre américaine et en offrant une série d'analyses qui, sans prétendre à l'exhaustivité, sont autant d'éclairages sur différents pays du continent. Loin d'être une expression univoque, la jeunesse est ici appréhendée comme une catégorie sociale construite, enjeu de luttes constantes et renvoyant à une extrême diversité de situations, allant de la condition ouvrière à l'engagement étudiant ou partisan, en passant par la déviance et la marginalité. La jeunesse est ici interrogée comme actrice et ressource politique, notamment à partir de la seconde moitié du XXe siècle. Le cycle contestataire des « années 1968 » apparaît ainsi indissociable des processus de politisation à « l'ère de la jeunesse » et même au-delà. Catégorie dominée, la jeunesse est elle-même traversée par des rapports de domination signifi és par le genre. Elle est également à la source de processus d'ethnicisation ou de racialisation, fruits d'une appropriation des assignations subies ou du pari émancipateur de l'altérité, voire de mobilisations antiracistes. Surreprésentée médiatiquement dans les sociétés contemporaines, la jeunesse s'avère aussi bien autrice qu'objet des diff érentes productions culturelles. Si elle n'est plus nécessairement une puissance démographique, elle demeure au centre des renouvellements des cultures de masse et de la vitalité créative des Amériques. Le continent pourrait-il réellement être pensé sans sa jeunesse ? Concevant l'âge comme une modalité du politique, l'ouvrage examine successivement les formes de politisations de la jeunesse, son altérité, ainsi que ses dimensions culturelles et médiatiques, allant du cinéma au hip-hop
Experimental Procedures for Mixed-Mode Fracture Testing of Bonded Beams Using a Dual-Actuator Load Frame
No full textInternational audienceExperimental Procedures for Mixed-Mode Fracture Testing of Bonded Beams Using a Dual-Actuator Load Fram
Integration of a novel Vernier-DSPM generator in a grid connected hybrid renewable energy system with battery storage
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Necessary Optimality Conditions for a Class of Bilevel Problems
No full textInternational audienceThis paper addresses a class of bilevel optimization problems involving an upper level problem which is a static optimization problem aimed at minimizing a first performance criterion over optimal trajectories. These trajectories are parameterized by a set of parameters (which has the structure of a metric space) and evaluated at a finite set of prescribed time instants. The optimal trajectories are the minimizers of a lower level problem, which is a dynamic optimization problem where the objective is to minimize a second cost functional over trajectory/control pairs on a given time interval. We consider intermediate-point problems (i.e. performance criteria take into account the values of the trajectories in the middle of the underlying time interval) including problems with free final and intermediate-point constraints, as well as problems with more general endpoint and intermediate-point constraints. We introduce, to the best of our knowledge, a new notion of solution for the reference bilevel problem: this is a pair composed of a control function and a family of associated trajectories that are optimal for both the upper and lower problems. We establish necessary conditions of optimality for these classes of bilevel problems by transforming them into single ‘min-min’ optimal control problems with uncertainty parameters. To derive our results, we employ perturbation methods to construct, with the help of Ekeland’s variational principle, a sequence of multiprocess optimization problems, on which we apply Clarke and Vinter’s multiprocesses theory together with techniques recently developed for optimal control problems with uncertainty parameters which can be adapted to the bilevel problem studied in the present paper
Autour de La Bibliotheque de La Croix-du Maine
No full textInternational audiencePublished in Paris in 1584 by François Grudé, sieur de La Croix du Maine, the Bibliotheque Françoise is a massive bio-biographical catalogue, whose abundance of details is as much fascinating as it is suspicious. This contribution first takes a look at the genesis of this curious work, from the Maine where the author was born, to the patronage of King Henri III that he craved, by way of a network of correspondents-informers in the provinces, which fed him with bibliographical news. The article then explore how François Grudé was connected to a local background. It demonstrates that the obvious bias of the author towards the Maine province reflects both the author's life history, the circles in which he moved, and his family alliances. The Bibliotheque françoise should therefore be read as a monument to learned friendships rather than as a questionable directory of ‘good authors’.Imprimées à Paris en 1584, La Bibliotheque françoise de François Grudé, sieur de la Croix du Maine, constituent un vaste catalogue bio-bibliographique à la profusion aussi fascinante que douteuse. La présente contribution revient en premier lieu sur la genèse de cette œuvre singulière, depuis le Maine, terre natale de l’auteur, jusqu’au patronage du roi Henri III qu’il convoitait, en passant par un réseau de correspondants-informateurs en province le nourrissant en nouvelles bibliographiques. Dans un second temps, l’article explore le rapport de François Grudé à l’ancrage local. Il montre que l’évident tropisme manceau des notices de l’ouvrage reflète à la fois l’itinéraire de son auteur, les milieux au sein desquels il a évolué ainsi que ses alliances familiales. La Bibliotheque françoise doit ainsi se lire comme monument dressé aux doctes amitiés, plutôt que comme un répertoire contestable de « bons auteurs »
« Et pourtant, si ça avait tourné différemment… » au lycée Charles-de-Gaulle (Rosny-sous-Bois)
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Unraveling The Failure Modes Of Solid-State Batteries: An In-Situ Synchrotron X-ray Laminography Electro-Mechanical Analysis
No full textInternational audienceLithium solid-state batteries (LiSSBs) are a promising alternative to conventional Li-ion batteries for electro-mobility, offering higher energy density and improved safety. However, their mechanical behavior, especially under normal and abuse conditions, remains poorly understood due to their complex multilayer structure (Li metal anode, solid electrolyte, composite cathode). Indeed, mechanical failure modes of LiSSBs, such as delamination at the electrode-electrolyte interfaces or electrolyte cracking, that can severely degrade performance of the batterie buy resp. affecting the capacity of the LiSSBs [1] or lead to partial internal short circuits [2]. Therefore, the battery failure modes are still unclear and are obstacles to overcome to identify areas of improvement of such technologies. In particular, indentation appears as the most representative loading to observe the failure sequence of a cell due to its resemblance with real-life loading scenarios [2].In this work we investigate the damage mechanisms in LiSSB pouch cells with varying configurations, Li symmetric cell vs. LiSSB [1,3], during mechanical indentation using in-situ 3D synchrotron imaging. Due to the large planar geometry of pouch cells (10 cm² surface area) compared to the micrometric scale of the active material within the polymer matrix of LiSSBs, a particular care was required to achieve sufficient resolution for monitoring the sample microstructural evolution during mechanical loading. To this end, a laminography setup at beamline ID19 of the ESRF synchrotron, combined with a custom-designed indentation device developed and validated to replicate normal and abusive loading conditions (voxel size of approximately 1 µm). During the in-situ experiment, two selected regions of interest were observed after each indentation loading steps to observe the damage propagation. The force (mechanical behavior) as well as open-circuit voltage and impedance (electrochemical behavior) were monitored continuously and simultaneously. For image analysis, digital volume correlation was performed to observe the progressive orthoradial and circumferential propagation of cracks and to map the quantified strain in the sample until short circuit. As the first outcome, such analysis provides the first quantitative insights into mechanical failure in LiSSBs under normal and abusive mechanical loading, guiding future design toward more robust and safer batteries, tailoring the cell assembly. By reducing imaging artefacts for high resolution with a large field of view compared to synchrotron standard laminography, this pioneering work illustrates the potential of in-situ synchrotron laminography to study planar devices coupling multiphysical conditions (e.g., structural, electrochemical and mechanical phenomena) that are used for energy storage with a high target resolution. [1] D. Devaux et al., (2015), J. Electrochem. Soc., doi: 10.1149/2.0721507jes[2] M. Kaliaperumal et al., (2021), Materials, doi: 10.3390/ma14195676[3] L. Magnier et. al., (2021), Front. Energy Res., doi: 10.3389/fenrg.2021.65771
