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Insights into human locomotion strategies and motor learning for an ageing population using transfer testing and coupled simulations
No full textInternational audienceThe elucidation of human locomotion strategies has potential applications in the prevention of sarcopenia and in the reduction of falls. Given the diverse biochemical, mechanical and functional age-related changes seen in the neuro-musculoskeletal system, the decline in motor function is difficult to study experimentally. In this study, we use transfer testing and coupled simulation strategies within a deep reinforcement learning environment to better understand the complex problem of motor control adaptation to age-related changes. Using transfer testing, a 3D musculoskeletal model is separately trained on parameters of the young adult model (Y) for either forward or backward falls after completing two steps forward, and tested using a 30% age-related reduction for all parameters (M_all). This strategy produces a backward fall for a forwardly trained simulation, showing potential sensitivity of these parameters to a given fall direction. Second, a coupled simulation solution is used to simulate recovery from falls by considering the center-of-mass position relative to the base of support. Results for the M_all trained model showed a longer simulation time and a greater vertical pelvis velocity with a maximal value of 4.26m/s. In particular, the results of the coupled simulations clearly show that both the young and M_all condition models respond with a step back and stronger leg extensor activations to propel the model forward to recover from the simulated fall. We developed a novel coupling between transfer testing and coupled simulation strategies to improve upon muscle models for characterizing muscle function, and also to begin testing different hypotheses, such as the strategy and force required to avoid a fall at different limits. This opens new avenues for precision rehabilitation with patient-specific muscle-driven recovery exercises
Operational Design Domain Monitoring through Uncertain Observations
No full textInternational audienceIntelligent vehicles are constantly increasing their automation levels; thus, it is necessary to ensure that such vehicles operate under conditions designed to guarantee safe operation. This paper proposes a method to address this challenge using the Operational Design Domain (ODD) concept and vehicle onboard real-time monitoring. The proposed method comprises a framework that estimates the state of the Operational Domain (OD) while considering measurement uncertainty to determine whether the vehicle is operating within its ODD. This method utilizes fuzzy sets to represent the vagueness of real-world driving environments. We also introduce a taxonomy-based approach to formally define ODDs with respect to vehicle capabilities, independent of the architecture. The approach is demonstrated through simulation use cases, by monitoring the vehicle's OD at runtime and determining when it operates outside its defined ODD. The results pave the way for the introduction of verifiable safety rules based on OD membership degrees
Modelling enlightenment: reassembling intertextual networks through data-driven research (ModERN)
No full textInternational audienceThe European Research Council's ModERN project (Modelling Enlightenment: reassembling networks of modernity through data-driven research) is a pioneering five-year research initiative. This programme seeks to redefine the conventional understanding of 18th-century literary history by employing advanced data-modelling and analysis techniques. By developing a comprehensive corpus of 18th-century French texts and leveraging a range of data-science methodologies such as text-reuse detection and network analysis, the project aims to uncover novel research avenues and provide fresh insights into early-modern French print culture and its intertextual dynamics. In this report, we discuss some theoretical points underlying our research; we explain the choices made in constructing our corpus and their implications; and we present some case studies to show the potential of our research and the most prudent methodologies to adopt
Utilisation de fonctions d'agrégation en optimisation topologique et application au design d'aimants supraconducteurs pour les IRMs hauts champs
No full textNational audienceL’amélioration de la technologie d’imagerie par résonance magnétique nucléaire tend aujourd’hui vers l’augmentation de la résolution de ses images. Ce gain de précision nécessite d’augmenter l’intensité du champ magnétique. Cela complexifie la conception de l’électroaimant supraconducteur car un champ plus élevé engendre des forces de Laplace plus importantes, conduisant à un problème de tenue mécanique du bobinage. L’optimisation topologique mariant magnétisme et mécanique apparaît alors comme une méthode adéquate pour répondre à ces exigences de conception. Ce travail propose une formulation mathématique du problème d’optimisation où la difficulté réside dans l’inconstance des forces de Laplace et leur dépendance aux variables de conception. Cette difficulté est illustrée sur un problème simplifié de treillis à trois barres. Celui-ci est utilisé pour développer une stratégie de résolution, par fonctions d’agrégation, dont nous discutons des résultats
Non-intrusive reduced order approximation for multi-physics problems
No full textNational audienceThis paper essentially depicts a methodology to address computational frugality of multiphysics problem using COMSOL Multiphysics. The first step is to decouple the involved physics using MATLAB Livelink with COMSOL. After the decoupling is established, a non-intrusive reduced order approximation is used through response surface method to replace the full order simulation of the most expensive physics. This essentially provides reduction in computational cost with acceptable accuracy as is depicted by an academic example
Verification and Validation of finite element models for laminated timber structures using solid, solid-beam and solid-shell approaches
No full textInternational audienceThis paper presents a numerical approach to assess efficiently the vibration performance of adhesive-free engineered wood products assembled through compressed wood dowels. Predictive finite element models are obtained by applying the Verification and Validation methodology. The models are first developed using solid elements. Then, solid-beam and solid-shell approaches based on standard solid elements are developed with first-order or higher-order theories. Beam or shell kinematic assumptions are applied throughout the cross-section of the dowels and through the thickness of the layers. From a numerical point of view, a modification of the system of algebraic equations, based on the concept of independent and dependent nodes, is developed. Dependent nodes are eliminated, resulting in a significant reduction in the number of degrees of freedom and floating-point operations. The methodology is evaluated for the calculation of frequencies and mode shapes of adhesive-free laminated timber beams and timber panels with a mix of solid elements, solid-shell and solid-beam approaches. The study highlights the efficiency of the proposed modelling approach in terms of quality of results and model size reduction
Application de la technologie des fluides supercritiques pour la formulation de dispersions solides amorphes de quercétine
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Experimental Validation of User Experience-focused Dynamic Onboard Service Orchestration for Software Defined Vehicles
No full textInternational audienceIn response to the growing need for dynamic software features in automobiles, Software Defined Vehicles (SDVs) have emerged as a promising solution. They integrate dynamic onboard service management to handle the large variety of user-requested services during vehicle operation. Allocating onboard resources efficiently in this setting is a challenging task, as it requires a balance between maximizing user experience and guaranteeing mixed-criticality Quality-of-Service (QoS) network requirements. Our previous research introduced a dynamic resource-based onboard service orchestration algorithm. This algorithm considers real-time invehicle and V2X network health, along with onboard resource constraints, to globally select degraded modes for onboard applications. It maximizes the overall user experience at all times while being embeddable onboard for on-the-fly decisionmaking. A key enabler of this approach is the introduction of the Automotive eXperience Integrity Level (AXIL), a metric expressing runtime priority for non-safety-critical applications. While initial simulation results demonstrated the algorithm's effectiveness, a comprehensive performance assessment would greatly contribute in validating its industrial feasibility. In this current work, we present experimental results obtained from a dedicated test bench. These results illustrate, validate, and assess the practicality of our proposed solution, providing a solid foundation for the continued advancement of dynamic onboard service orchestration in SDVs
Description et analyse des stratégies de nage chez 11 chevaux entrainés dans une piscine en U
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Decentralized Collaborative Localization and Map Update with Buildings
No full textInternational audienceIn urban environments where GNSS performance is degraded, localization can be performed using stable and geo-referenced map features detected by on-board sensors. Prior maps are prone to errors which have a direct impact on localization accuracy. By exchanging observed features and sharing their maps, vehicles can simultaneously improve their localization and update the map. This paper deals with indirect collaboration, where vehicles do not observe each other directly. The features are obtained from building facades using 3D lidar sensors. The paper emphasizes real-time decentralized collaboration with direct communication between vehicles, without the need for a central server. The collaboration takes place when vehicles perceive the same geo-referenced facades. Vehicle poses and maps are collaboratively updated using a Schmidt Kalman filter that carefully manages the cross-covariance terms. To maintain consistent estimates, the Kullback-Leibler Average is used. We also present a lidar data processing pipeline to obtain reliable observations from building facades. Real tests carried out with experimental vehicles on the university campus are reported. The results show that indirect collaboration makes a significant contribution to localization and map update when compared to a standalone method