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Holistic adaptive energy-efficient MPC architecture for multi-objective control in over-actuated autonomous vehicles
No full textInternational audienceThis paper presents two novel MPC architectures for autonomous over-actuated in-wheel vehicles, targeting enhanced energy efficiency, stability, and control performance. The first architecture introduces a hierarchical centralized MPC framework that utilizes a minimal-order model to integrate path-tracking, speed control, and stability control objectives. The second architecture extends the hierarchical framework into a holistic MPC design, incorporating direct energy-efficient torque allocation and a tire stability criterion. Energy efficiency is significantly improved by minimizing total power consumption and enforcing operational constraints to maximize motor efficiency. Central to both architectures is a novel multi-criteria adaptive weighting mechanism that dynamically reconciles conflicting objectives by adjusting control priorities based on real-time error magnitudes and driving conditions. This mechanism not only resolves potential conflicts between objectives but also enhances robustness to modeling inaccuracies, uncertainties, disturbances, and variations in road adhesion, while significantly improving control performance. Validation is conducted through joint simulations in Simulink/Matlab and the SCANeR Studio vehicle dynamics simulator. The findings demonstrate that both architectures achieve substantial energy savings while maintaining computational efficiency, with improved stability, comfort, and precision in path-tracking and speed control under challenging conditions, including high-speed, high-curvature, and low-adhesion scenarios
A Rocq Formalization of Monomial and Graded Orders
No full textEven if binary relations and orders are a common formalization topic, we need to formalize specific orders (namely monomial and graded) in the process of formalizing in Rocq the finite element method. This article is therefore definitions, operators, and proofs of properties about relations and orders, thus providing a comprehensive Rocq library. We especially focus on monomial orders, that are total orders compatible with the monoid operation. More than its definition and proved properties, we define several of them, among them the lexicographic and grevlex orders. For the sake of genericity, we formalize the grading of an order, a high-level operator that transforms a binary relation into another one, and we prove that grading an order preserves many of its properties, such as the monomial order property. This leads us to the definition and properties of four different graded orders, with very factorized proofs. We therefore provide a comprehensive and user-friendly library in Rocq about orders, including monomial and graded orders, that contains more than 700 lemmas
Towards a New Industrial Revolution? Entropy and its Challenges
No full textInternational audienceMarie Chollat-Namy and I were members of the Association, students of the life sciences and humanities</div
: Multi-scale Computational Methods for Solids and Fluids
No full textInternational audienceECCOMAS MSF 2025 is the seventh in the series of International Conferences focusing upon Computational Methods in Solids and Fluids, held every two years in different countries in Europe. Previous meetings have all been organized under umbrella of ECCOMAS, ‘The European Community on Computational Methods in Applied Sciences’, as the sponsor of ECCOMAS conference series. For this particular Conference, we have an additional sponsor from the host country: University of Split, Croatia. The institutions organizing ECCOMAS MSF 2025 are Faculties of Civil Engineering, Architecture and Geodesy in Split, Croatia and of Civil Engineering and of Mechanical Engineering of University of Sarajevo, B-H, in collaboration with University ofTechnology Compiegne, a member Alliance of Sorbonne University. The ECCOMAS MSF 2025 is held from June 25 to 27, 2025 in Split, after the short course offered to young participants held from June 23 to 24, 2025. The Conference seeks to provide a platform for learning from some of the worlds' leading specialists in numerical methods, coming from different engineering disciplines and applied mathematics.</div
"Did she just tap me?": Qualifying Multisensory Feedback for Social Touch during Human-Agent Interaction in Virtual Reality
No full textInternational audienceSocial touch is one of the many modalities of social communication. It can take many forms (from handshakes to hugs) and can convey a wide variety of emotions and intentions. Social touch is also multimodal: it is not only comprised of haptic feedback (both tactile and kinesthetic), but also visual feedback (gestures) and even audio feedback (sound of the hand movement on the body). Virtual agents (VA) can perceive and interact with users by making use of multimodality to express attitudes and complex emotions. There are still few studies that have investigated how to integrate touch into VAs' social abilities, despite a growing interest in haptic interactions within immersive virtual environments (IVE). While prior work has examined haptic feedback, auditory substitution, or agent-based touch in isolation, no study has systematically disentangled the respective and combined contributions of visual, auditory, and tactile cues to the perception of being socially touched by a virtual agent. To address this gap, we conducted three experiments that progressively isolate and combine modalities, revealing how each shapes touch recognition, believability, and agency attribution. Taken together, our results show that multisensory feedback improves experience of social touch, which is in line with previous research in IVEs. They also show that visual feedback has the potential to guide the recognition of the stimulus the most but both audio and tactile feedback further help disambiguate the recognition of a touch gesture in particular cases. The results also show that both level of animation and interpersonal distance are essential to how much the VA is felt as a social agent when initiating touch. While visual feedback and tactile feedback are the main contributors to participants feeling touched by the VA, audio feedback also has a significant impact.</div
Impact of levels of detail (LOD) in the digital model on solar resource estimation
No full textInternational audienceUrban digital modelling is a complex process that involvesheterogeneous data sources (point clouds, site plans, GIS data),facilitating their integration and ensuring consistency. Digital modelsstandardised according to the CityGML specification are created atvarious levels of detail (LOD), which define the data required for themodelling of these digital representations.The aim of this article is to examine the relevance of usingdifferent levels of detail in modelling for solar potential estimation,using the CitySIM software. The study demonstrates that these levelsof detail have a significant impact on the accuracy of the solarpotential of digital models, although the extent of this impact variesdepending on the data progressively integrated during the modellingprocess
A Hybrid Physics-Informed and Data-Driven Approach for Predicting the Fatigue Life of Concrete Using an Energy-Based Fatigue Model and Machine Learning
No full textInternational audienceFatigue has always been one of the major causes of structural failure, where repeated loading and unloading cycles reduce the fracture energy of the material, causing it to fail at stresses lower than its monotonic strength. However, predicting fatigue life is a highly challenging task and, in this context, the present study proposes a fundamentally new hybrid physics-informed and data-driven approach. Firstly, an energy-based fatigue model is developed to simulate the behavior of concrete under compressive cyclic fatigue loading. The data generated from these numerical simulations are then utilized to train machine learning (ML) models. The stress–strain curve and S-N curve of concrete under compression, obtained from the energy-based model, are validated against experimental data. For the ML models, two different algorithms are used as follows: k-Nearest Neighbors (KNN) and Deep Neural Networks (DNN), where a total of 1962 data instances generated from numerical simulations are used for the training and testing of the ML models. Furthermore, the performance of the ML models is evaluated for out-of-range inputs, where the DNN model with three hidden layers (a complex model with 128, 64, and 32 neurons) provides the best predictions, with only a 0.6% overall error
Experimental characterisation and modelling of the fission products implantation at the fuel-cladding interface of high burnup PWR fuel rods
No full textInternational audienceDuring irradiation in light water reactors, numerous fission products are produced by the fission reactions. At the periphery of the fuel, these elements implant by recoil in the cladding inner oxide layer (zirconia) located at the fuel-cladding interface (FCI). In the present study, two irradiated UO2 fuel rods with high burnups (61.4 and 62.7 GWd/tU) have been analysed using EPMA. The aim of this work was to understand the mechanisms behind zirconia growth, FPs implantation at the FCI and their impact on the interface. In this objective, the measured elemental concentration profiles of U and Zr at the FCI is first compared to Fission Enhanced Diffusion (FED) models derived from out-of-pile experiments, showing good agreement. It is then shown that the implantation of metallic fission products (Nd, Mo, Pd, Ru) in the zirconia layer at the FCI can be described by a ballistic mechanism. Volatile fissions products such as Xe and Cs are found to affect differently the interface as they gather in bubbles, explaining the zirconia growth in form of protuberances called “circumvolutions” that are typically found in high burnup fuel rods. An analytical model describing zirconia swelling due to gaseous FP is proposed and compared successfully to measurements of zirconia thickness and circumvolution height
Localisation de vibration dans les membranes avec résonances de masses concentrées : comment adapter la théorie du paysage ?
No full textMatériaux poreux et métamatériaux acoustiques; GAPSUS - Acoustique Physique, Sous-Marine et Ultra-Sonore: GVB - Vibro acoustique et Contrôle du Bruit: GABE - Acoustique du Bâtiment et de l'EnvironnementNational audienceLa localisation d’ondes, phénomène caractérisé par la concentration de l’énergie ondulatoire dans une région d’un milieu désordonné, intervient dans l’ensemble de la physique des ondes. Cette concentration d’énergie peut être vue comme une absence de propagation des ondes dans un milieu infini ou comme l’apparition de modes propres localisés dans un milieu fini. Dans le cadre des vibrations de plaques minces et de membranes, il a été montré que lorsque le désordre provient de points bloqués ou de zones bloquées, les premiers modes sont localisés. Dans ce cas, un nouvel outil théorique, le paysage de localisation, permet de prédire les régions et les fréquences des modes localisés à partir de la déformée statique de la structure. En revanche, lorsque le désordre provient de résonateurs locaux, les premiers modes sont globaux et les modes localisés interviennent à plus haute fréquence. Dans ce cas, la déformée statique est insensible au désordre. Le paysage ne permet alors plus d’obtenir d’informations a priori sur la localisation. Nous prenons comme point de départ l’étude d’une membrane avec des masses ajoutées comme résonateurs locaux. L’introduction d’un résonateur sur la membrane fait apparaître un phénomène de croisement évité en fréquence en fonction du paramètre de masse ajoutée. Ainsi, si le contraste de masse est assez important, le résonateur et la membrane sont faiblement couplés et la masse est quasi immobile au voisinage du premier mode propre de la membrane homogène. On parle alors de mode localisé sur la membrane. Ce travail propose d’exploiter la quasi immobilité de la masse afin d’introduire des propriétés effectives dans le paysage de localisation dans le cas où le paysage classique n’est plus adapté. De cette manière, une perspective déterministe à l’étude de la localisation haute fréquence des vibrations est proposée