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Optimized VMD-Transformer Framework for Accurate Remaining Useful Life Prediction of Lithium-Ion Batteries
No full textInternational audienceThis study introduces an Optimized Variational Mode Decomposition-Transformer framework (OVMD-Transformer) for accurate Remaining Useful Life (RUL) prediction of Lithium-ion Batteries (LiBs). First, key VMD hyperparameters, notably the number of Intrinsic Mode Functions (IMFs), are automatically tuned via the Particle Swarm Optimization (PSO) objective function, removing the need for manual parameter selection. The resulting IMFs, which isolate high-frequency capacity fluctuations and low-frequency aging trends, are independently fed into a dedicated Transformer network model to capture multiscale degradation dynamics. The proposed model is rigorously validated on National Aeronautics and Space Administration (NASA) (B0005, B0006, B007, B0018) and Center for Advanced Life Cycle Engineering (CALCE) (C35-C38) datasets under multiple training-testing splits (50%/50% and 30%/70% for NASA; 50%/50% and 20%/80% for CALCE). On the NASA data, the proposed model achieves perfect RUL alignment (Absolute Error Rate (AER) is 0%) while maintaining R2 > 0.95. The CALCE dataset similarly sustains R2 > 0.99 with all prediction relative errors lower than 3%. Moreover, the framework excels in early-stage forecasting, delivering reliable RUL estimates from just the first 30% (NASA) or 20% (CALCE) of the capacity data. These results demonstrate that OVMD-Transformer significantly outperforms other approaches’ accuracy and robustness
Design of SMA wire based actuators : a phase transformation and electric coupling parametric study
No full textInternational audienceNew strategies for the design of Shape Memory Alloy (SMA) actuators are needed to fill the gap between their high potential and limited industrial implementation. This gap stems from a number of challenges, such as the need for robust methods to predict and track their thermomechanical behavior under varying operational conditions, the lack of tools to model and mitigate functional fatigue during cycling, and the absence of systematic design frameworks that take into account the complex interdependencies of activation parameters. In this regard, this work proposes a straightforward strategy for designing SMA wire actuators based on parametric simulations of their thermomechanical behavior. The influence of key activation parameters, including heating time, cooling time, electrical current, axial stress, and wire diameter, on SMA actuator performance is investigated by focusing on initial actuation strain and maximum operating temperature. An experimental study is performed to explore the interdependencies of these parameters and their impact on the actuator behavior. On this basis, a new parametric analysis method is proposed to identify optimal actuation parameters for various operating conditions. The method consists of a three-step approach. Each step focuses on different aspects of the SMA actuation (e.g. activation conditions, SMA dimensions and SMA cyclic behavior) that together address the majority of imposed industrial specifications
Les grands contentieux liés aux occupations irrégulières du domaine public maritime naturel en Bretagne
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Polymorphism and singularity of the Second Mesolithic of Southern France
No full textInternational audienceBetween the middle of the 7th and 6th millennia BCE, with the spread of the « Blade and Trapezes Complex « (BTC), southern France can be divided into two main groups, based on lithic production. In the East, in from the Mediterranean to the northern Alps, the Castelnovian complex, first defined by Max Escalon de Fonton, is characterised by the production of regular blades produced by pressure or indirect percussion, from which various types of trapezoidal, often asymmetrical, arrowheads were later derived. To the West, from the plains of Roussillon to the Atlantic coast, the so-called absence of laminar production and the existence of an original type of armature, such as « Gazel points » or « Bastard points », testify to the presence of another cultural sphere. During the 80's, some referred to as the ‘Cuzoul Gazel group', a notion now abandoned for lack of internal coherence and chronlogical inconstancy. This Second Mesolithic of Occitania and Aquitaine is actuly under revision due to a major documentary renewal, with the excavation of several sites and the revision of other lithic and chronostratigraphic assemblages, especially in the area between the Rhône Valley and the Aude. Our talk will therefore provide an opportunity to take stock of the available data and to determine whether or not these industries are original in terms of the spread of the blade and trapeze complex
Shaping Expressiveness in Robotics: The Role of Design Tools in Crafting Embodied Robot Movements
No full textInternational audienceAs robots increasingly become part of shared human spaces, their movements must transcend basic functionality by incorporating expressive qualities to enhance engagement and communication. This paper introduces a movementcentered design pedagogy designed to support engineers in creating expressive robotic arm movements. Through a handson interactive workshop informed by interdisciplinary methodologies, participants explored various creative possibilities, generating valuable insights into expressive motion design. The iterative approach proposed integrates analytical frameworks from dance, enabling designers to examine motion through dynamic and embodied dimensions. A custom manual remote controller facilitates interactive, real-time manipulation of the robotic arm, while dedicated animation software supports visualization, detailed motion sequencing, and precise parameter control. Qualitative analysis of this interactive design process reveals that the proposed "toolbox" effectively bridges the gap between human intent and robotic expressiveness resulting in more intuitive and engaging expressive robotic arm movements.</div
Technical, cultural and economic variabilities on the Mesolithic-Neolithic transition at Montclus (Gard, France, 6300-5000 cal. BCE): crossed lithic and zooarchaeological perspectives
No full textInternational audienceFor the Late Mesolithic, the Castelnovian techno‐complex is often perceived as a monolithic entity, defined solely by lithic technology and the presence of regular blades produced by indirect percussion or pressure, as well as trapezoidal microliths. Similarly, the onset of the Neolithic is often understood only through ceramic data, which limits our ability to examine the transition between these two entities. Consequently, the consideration of a multiplicity of proxies, particularly through the integration of functional and archaeozoological data, allows for a more nuanced approach to these phenomena. The site of La Baume de Montclus in southern France, with its well‐developed stratigraphy, serves as an illustrative case in point. Several occupations attributed to the Late Mesolithic and Early Neolithic are distributed between 6300 and 5000 BCE and have yielded abundant lithic and faunal assemblages. A previous study focused on the rich corpus of arrowheads revealed significant changes in the production and hafting modalities of these armatures. These findings suggested that techno‐functional discontinuities could serve as markers of economic or socio‐cultural transformations. Building on this work, we now propose to expand this preliminary evolutionary framework by incorporating results from the analysis of the entire lithic ‘chaîne opératoires', traceological studies of the full range of knapped stone tools, and the variability of faunal spectra. The objective is to investigate changes in hunting practices and environmental exploitation, as well as butchery activities, with particular attention to carcass and hide processing
Evaluation of binary classifiers for asymptotically dependent and independent extremes
No full textMachine learning classification methods usually assume that all possible classes are sufficiently present within the training set. Due to their inherent rarities, extreme events are always under-represented and classifiers tailored for predicting extremes need to be carefully designed to handle this under-representation. In this paper, we address the question of how to assess and compare classifiers with respect to their capacity to capture extreme occurrences. This is also related to the topic of scoring rules used in forecasting literature. In this context, we propose and study a risk function adapted to extremal classifiers. The inferential properties of our empirical risk estimator are derived under the framework of multivariate regular variation and hidden regular variation. A simulation study compares different classifiers and indicates their performance with respect to our risk function. To conclude, we apply our framework to the analysis of extreme river discharges in the Danube river basin. The application compares different predictive algorithms and test their capacity at forecasting river discharges from other river stations
Naturisme versus fatigue : le retour à la nature comme remède à la « fatigue moderne » (XIXe-milieu XXe siècle)
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« Il préfère la vie à l’hôpital à la vie à la prison. » Quand l’interné s’approprieles frontières du pathologique (Madagascar, années 1910-1960)
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Le métier d’enseignant-chercheur questionné par la mise en place de l’approche par compétences dans les Instituts Universitaires de Technologie
No full textInternational audienceSetting up a new training system often involves a series of levers and obstacles within an educational community. The ternary model for analysing systems proposed by Albero (2010) distinguishes three main areas: the ‘ideal’ dimension, based on values and the political or institutional project ; the ‘functional reference’ which includes tools, methods and operating rules ; the ‘lived experience’ of those involved, who may be trainers, learners, coaches, but also adults undergoing training, etc. These three dimensions, which can complement or oppose each other in a process of interaction, can be used to rebuild and reconfigure the systems. The introduction of the Bachelor's degree in University Institutes of Technology coupled with a new pedagogical paradigm, the competency-based approach (APC), is beginning to highlight a number of developments. This article uses an ethnographic approach to identify and categorise the issues and difficulties faced by teacher-researchers in implementing the APC in their teaching practices, as well as in their relationship with research.La mise en place d’un nouveau dispositif de formation entraîne souvent une série de leviers et de freins au sein d’une communauté éducative. Le modèle d’analyse ternaire des dispositifs proposé par Albero (2010) distingue trois grands champs : la dimension « idéelle » portée par les valeurs, le projet politique ou institutionnel ; la dimension « fonctionnelle de référence » qui regroupe les outils, les méthodes, les règles de fonctionnement ; la dimension du « vécu » des acteurs qui peuvent être les formateurs, les apprenants, les accompagnateurs, mais aussi les adultes en formation. Ces trois dimensions qui peuvent se compléter ou s’opposer dans une logique d’interactions permettent de reconstruire, de reconfigurer les dispositifs. La mise en place dans les Instituts Universitaires de Technologie (IUT) du « Bachelor » couplée avec un nouveau paradigme pédagogique, l’approche par compétences (APC) commence à faire ressortir plusieurs évolutions. Cet article, dans une approche ethnographique, propose d’identifier et de catégoriser les questionnements et les difficultés des enseignants-chercheurs dans la mise en place de l’APC dans leurs pratiques pédagogiques, mais aussi dans leur rapport à la recherche