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Optimal Multi-Objective Adaptive Coordinated Control via Hierarchical MPC Framework for Autonomous Vehicles
No full textInternational audienceThis paper introduces a novel minimum-order, multi-objective centralized MPC control architecture for autonomous vehicles. The contributions are fourfold. First, we propose a hierarchical architecture that integrates path-tracking, speed control, and stability control based on a minimum-order predictive model. Second, stability control is dynamically activated and relaxed using an adaptive weight, based on a stability index. Third, speed control employs an adaptive weight to improve robustness, reduce overshoot and oscillations, and enhance energy efficiency. Fourth, path-tracking control is enhanced with an adaptive weighting scheme that considers lateral error, road adherence, and curvature to ensure smooth convergence and prevent oscillations, while also improving accuracy under uncertain and low-adherence conditions. The architecture is validated in a joint simulation between Simulink/Matlab and SCANeR Studio vehicle dynamics simulator. Our findings demonstrate the effectiveness of the architecture in enhancing stability and comfort at low runtime, while maintaining path-tracking precision and speed control robustness, at high speeds, high curvature, and low adhesion
Model-Based End-to-End Learning for Multi-Target Integrated Sensing and Communication under Hardware Impairments
No full textInternational audienceWe study model-based end-to-end learning in the context of integrated sensing and communication (ISAC) under hardware impairments. Hardware impairments are usually addressed by means of array calibration with a focus on communication performance. However, residual impairments may exist that affect sensing performance. This paper proposes a data-driven framework for mitigating such impairments. A monostatic orthogonal frequency-division multiplexing (OFDM) sensing and multiple-input single-output (MISO) communication scenario is considered, incorporating hardware imperfections at the ISAC transceiver antenna array. Since conventional ISAC signal processing algorithms rely on mathematical models of the wireless channel, a mismatch occurs between the assumed mathematical models and the underlying reality in the presence of hardware impairments. We first study the detrimental effects of such impairments at the transmitter and receiver side of the proposed scenario, showcasing different levels of degradation on communication and sensing performances. As the core contribution of this work, we propose a novel differentiable version of the orthogonal matching pursuit (OMP) algorithm that is suitable for multi-target sensing and allows for efficient end-to-end learning of the hardware impairments. Based on the differentiable OMP, we devise two model-based parameterization strategies of the ISAC beamformer and sensing receiver to account for hardware impairments: (i) learning a dictionary of steering vectors for different angles and (ii) learning the parameterized hardware impairments. We carry out a comprehensive performance analysis of the proposed model-based learning approaches and a strong baseline consisting of least-squares beamforming, conventional OMP, and maximum-likelihood symbol detection for communication. Results show that by parameterizing the hardware impairments, learning approaches offer gains in terms of higher detection probability, position estimation accuracy, and lower symbol error rate (SER) compared to the baseline. We demonstrate that learning the parameterized hardware impairments outperforms learning a dictionary of steering vectors, also exhibiting the lowest complexity
Architecture Educates ! Au contact de l'art
No full textNational audienceL'éducation retournée par les arts : le célèbre anthropologue anglais Tim Ingold nous invite à considérer l'art, l'architecture et le design arts comme la base même d'une éducation pour le XXIe siècle en prise aux enjeux sociaux et écologiques auxquels nous sommes confrontés.« Sous l'acronyme STEM, l'éducation dans les disciplines scientifiques, techniques, ou encore mathématiques a été soumise aux implacables demandes de l'économie néolibérale de la connaissance. Les étudiant·es sont considéré·es alors comme des consommateur·trices, et les éducateur·trices comme des prestataires de services, chargé·es de fournir les produits que leurs étudiant·es souhaitent acquérir.Que peuvent l'art et l'architecture dans ce contexte ? Dans ce qui suit, j'exposerai trois réponses possibles à cette question.
A new ISO standard for the experimental characterization of in-plane permeability of fibrous reinforcements
No full textInternational audienceDuring Liquid Composite Molding, a fibrous reinforcement is impregnated with liquid resin. Process design requires knowledge of the reinforcement permeability for fluid flow, but until recently, there has been no standard available for its measurement. In 2023, following decades of benchmarking activities and a standardization project, an ISO standard for the experimental characterization of in-plane permeability of fibrous reinforcements for liquid composite molding was finally published. It focuses on the experimental characterization of unsaturated in-plane permeability and specifies the requirements for test equipment, methods and data analysis. Given the deficiency of standardized procedures within the composites industry, this paper intends to provide an example of the steps towards standardization and summarizes lessons learned. It illustrates the research milestones that led to the establishment of the standard, promotes the standard by detailing its general content and notable features and finally gives explanations and reasoning behind the developed guidelines
Topology optimization for dual-flow heat exchangers of moderate conductive material within a narrow design domain: Numerical and experimental investigations
No full textInternational audienceHeat exchangers (HXs) play a critical role in various energy systems, which can largely influence their overall efficiency. Most recently, the interest in the topology optimization (TO) of heat transfer, which can derive innovative thermal designs, is growing rapidly. Therefore, the present work investigates the utility of the densitybased TO for dual-flow HX unit of moderate conductive material (Stainless Steel (SS)) and narrow design domain, along with CFD (computational fluid dynamics) and experimental verifications. The objective of the TO is to maximize the heat exchange rate, while a pressure drop constraint is imposed on the HX's flow channels to avoid the blocking issues. An in-depth investigation is conducted to study the effect of various TO's input parameters on the derived topology. The obtained results reveal that the TOderived design is mainly featured by the solid allocation in proximity to the insulation walls but not at the interface wall that separates hot and cold fluids (where heat is exchanged). Furthermore, high fidelity CFD simulations along with experimental approaches (including Infrared thermography) are employed to validate the TO's design methodology and the numerical model. The experimental and numerical results present good agreement between each other, demonstrating the thermo-hydraulic performance superiority of the TO-acquired design compared to the benchmark case with an intensification in the exchanged heat up to 15% under the same pumping power.Lastly, a physical interpretation is delivered to analyze the underlying physics behind the TO-acquired topologies
Identifier le contrôle coercitif et les conséquences psychosomatiques dans les violences conjugales : une analyse qualitative du vécu de quatre femmes suivies dans une unité de prise en charge du psychotraumatisme
No full textInternational audienceAbstractCoercive control refers to a set of behaviors used by an individual to dominate, intimidate, or manipulate another person through various methods such as isolation, threats, surveillance, and deprivation of needs. This complex phenomenon, popularized by Stark (2007), has been the subject of studies for several decades (Dutton & Goodman, 2005; French et al., 1959; Okun, 1986). If coercive control is not detected or if it is identified too late, the insufficiently protected victim will then suffer physical and psychological health consequences. The repetition and cumulative effect of violence worsen over time, hindering victims in the judicial processing of the violence they have experienced.ObjectiveThis study aims to provide a clinical illustration of coercive control and its somatopsychic consequences in women victims of intimate partner violence perpetrated by their partner. We conducted a qualitative analysis of clinical interviews from four psychological follow-ups representing women victims of intimate partner violence followed within a psycho-trauma unit in the Ile-de-France region.ResultsThe synthetic restitution of the clinical vignettes presented highlights the establishment of coercive control early in the relationship between the perpetrator and the victim, with a range of behaviors triggering early micro-management of verbal and psychological violence, establishing a continuum from the beginning and evolving throughout the relationship, including after separation.ConclusionTraining professionals in identifying mechanisms of coercive control could enable early systematic screening in the medical-psycho-social-judicial sector and propose concrete preventive actions against intimate partner violence and femicides. It could also facilitate the dissemination in France of a coercive control screening scale, as suggested by the team (K. Wilson, 2022; K. D. Wilson & Fritz, 2023) in their work with which we wish to collaborate in France.IntroductionLe contrôle coercitif désigne un ensemble de comportements utilisés par un individu pour dominer, intimider ou manipuler une autre personne par le biais de différents procédés comme l'isolement, la menace, la surveillance et la privation des besoins. Ce phénomène complexe popularisée par Stark (2007) est l’objet d’études depuis plusieurs décennies (Dutton & Goodman, 2005; French et al., 1959; Okun, 1986). Si le contrôle coercitif n’est pas repéré ou s’il l’est trop tardivement, la victime insuffisamment protégée présentera alors des séquelles sur le plan de la santé physique et psychique. La répétition et l’effet cumulatif des violences vont s’aggraver avec le temps jusqu’à entraver les victimes dans le traitement judiciaire des violences subies. Objectif Cette étude vise à proposer une illustration clinique du contrôle coercitif et de ses conséquences somatopsychiques chez des femmes victimes de violences conjugales perpétrées par leur conjoint. Nous avons procédé à une analyse qualitative des entretiens cliniques de quatre suivis psychologiques représentatif de femmes victimes de violences conjugales suivies au sein d’une unité de psycho-traumatisme en Ile de France et Résultats La restitution synthétique des vignettes cliniques présentées met en évidence la mise en place d’un contrôle coercitif dès le début de la relation entre auteur et victime, avec un registre de comportements variés, qui va enclencher très tôt la mise en place de micro-gestion de comportements dans les violences verbales et psychologiques, en installant un continuum dès leur démarrage et évoluant tout au long de la relation y compris après la séparation. Conclusion La formation des professionnels à l’identification des mécanismes de contrôle coercitif pourrait permettre un dépistage systématique précoce auprès du secteur médico-psycho-socio-judiciaire et de proposer des actions préventives concrètes contre les violences conjugales et les féminicides. Elle pourrait permettre également la diffusion en France d’une échelle de repérage du contrôle coercitif comme l’a suggéré l’équipe (K. Wilson, 2022; K. D. Wilson & Fritz, 2023) dans leurs travaux auxquels nous souhaitons nous associer en France
¿Cómo nos hace felices la naturaleza en la ciudad? El papel del afecto y la conexión con la naturaleza
No full textInternational audienceClimate change is generating harmful consequences, specifically in urban environments. Re/naturalizing urban areas and stimulating the connectedness to nature of a significant number of individuals may be responses to mitigate these effects. The main objective of this study is to investigate the interactions between perceived exposure to nature in the city in terms of quality and frequency, positive and negative affect, and subjective well-being by considering connectedness to nature as a moderator of these interactions. Data were collected by convenience using an online questionnaire. Participants had been living for at least one year in a French city of more than 100,000 inhabitants. The final sample consisted of N = 479 participants. Structural equation modelling showed that perceived exposure to nature in the city improves positive affect that contributes to subjective well-being and that the more connected individuals are to nature, the better. Implications and perspectives are discussed for the mitigation of the deleterious effects of climate change
Radon Removal in XENONnT down to the Solar Neutrino Level
No full textInternational audienceThe XENONnT experiment has achieved an unprecedented reduction of the Rn activity concentration within its liquid xenon dual-phase time projection chamber to a level of (0.900.01stat.0.07 sys.)Bq/kg, equivalent to about 1200 Rn atoms per cubic meter of liquid xenon. This represents a 15-fold improvement over the Rn levels encountered during XENON1T's main science runs and is a factor five lower compared to other currently operational multi-tonne liquid xenon detectors engaged in dark matter searches. This breakthrough enables the pursuit of various rare event searches that lie beyond the confines of the standard model of particle physics, with world-leading sensitivity. The ultra-low Rn levels have diminished the radon-induced background rate in the detector to a point where it is for the first time lower than the solar neutrino-induced background, which is poised to become the primary irreducible background in liquid xenon-based detectors
PEGSGraph: A Graph Neural Network for Fast Earthquake Characterization Based on Prompt ElastoGravity Signals
No full textInternational audienceAbstract State‐of‐the‐art earthquake early warning systems use the early records of seismic waves to estimate the magnitude and location of the seismic source before the shaking and the tsunami strike. Because of the inherent properties of early seismic records, those systems systematically underestimate the magnitude of large events, which results in catastrophic underestimation of the subsequent tsunamis. Prompt elastogravity signals (PEGS) are low‐amplitude, light‐speed signals emitted by earthquakes, which are highly sensitive to both their magnitude and focal mechanism. Detected before traditional seismic waves, PEGS have the potential to produce unsaturated magnitude estimates faster than state‐of‐the‐art systems. Accurate instantaneous tracking of large earthquake magnitude using PEGS has been proven possible through the use of a Convolutional Neural Network (CNN). However, the CNN architecture is sub‐optimal as it does not allow to capture the geometry of the problem. To address this limitation, we design PEGSGraph, a novel deep learning model relying on a Graph Neural Network (GNN) architecture. PEGSGraph accurately estimates the magnitude of synthetic earthquakes down to 7.6–7.7 and determines their focal mechanisms (thrust, strike‐slip or normal faulting) within 70 s of the event's onset, offering crucial information for predicting potential tsunami wave amplitudes. Our comparative analysis on Alaska and Western Canada data shows that PEGSGraph outperforms PEGSNet, providing more reliable rapid magnitude estimates and enhancing tsunami warning reliability
Holocene paleoenvironmental reconstructions in western Brittany Bay of Brest: Part I – Understanding the spatial distribution of palynological records
No full textInternational audienceThe Bay of Brest (BB) is a shallow estuarine environment in NW France. This semi-enclosed basin of 180 km² is subject to multiple hydrodynamic factors including the dual influence of oceanic currents and fluvial discharges (Aulne and Elorn main rivers) and resulting in complex hydro-climatic and hydro-sedimentary processes. This study investigates with palynological data (continental: pollen grains and marine: dinoflagellate cysts) two kinds of different materials: (i) modern surface sediments collected over the whole BB as well as (ii) three new BB sediment cores (core ‘F’ from the mouth of the Aulne river and cores PALM-KS05 and PALM-KS06 from the Brest harbour). While modern data are analysed from a statistical point of view to highlight the influence of hydrodynamic forcing on the modern distribution of palynomorphs, the cores allow for spatial comparisons of palynological data on three windows over the Early (~9.5 and ~8.5 ka BP), Middle (~4.4–4.3 ka BP interval) and Late (~1–0.9 ka BP interval) Holocene. For each time intervals, two cores located along a transect from west (more pronounced oceanic influence) to east (more intense fluvial influence from the Aulne river) are compared, located on either side of a limit that we referred to as the river-induced palynological signal (RIPS) limit. These different comparisons reveal a high degree of spatial homogeneity in BB pollen records over time, with exceptions for environments east of the RIPS limit, for which rainfall-induced fluvial discharges have a stronger impact especially considering riparian taxa (i.e. Alnus). This is intended to improve understanding of the palynological signals recorded at different BB coring sites, a first step of crucial relevance before the establishment of a palynological stack covering the Holocene from several cores collected in different shallow bays of the BB (see Valero et al., submitted – PART II)