HAL Université de Toulouse, et Toulouse INP
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Thermal investigations of supercritical CO 2 jet impingement and its cooling applicability in a machining context
No full textInternational audienceIn recent years, the use of supercritical carbon dioxide (sCO2) as cutting fluid during machining operations has gained attention of the manufacturing community. The present paper intends to address thermal characteristics of sCO2 free jet impingement on a hot plate. An experimental approach has been hereby chosen in order to assess the heat transfer coefficient (HTC) in various experimental conditions. Infrared thermography along with high speed imaging are set up in order to access the cooling of a titanium plate. HTC is then calculated from an analytical solution of the heat transfer equation adapted to the specific conditions of the proposed setup.Investigations are focused on the influence of nozzle-to-plate distance (from 4 to 106 times jet diameter), angle of incidence (from 90° to 50°) and flow initial temperature (40 ◦C to 80 ◦C) and pressure (100 bar to 285 bar).Results provide with metric and dimensionless values of the HTC. Preliminary conclusions are drawn from the presence of solid carbon dioxide at the plate’s surface and leads are proposed to investigate in further detail the effect of the jet nature and structure on its cooling ability
Learning Geometric Reasoning Networks for Robot Task and Motion Planning
No full textInternational audienceTask and Motion Planning (TAMP) is a computationally challenging roboticsproblem due to the tight coupling of discrete symbolic planning and continuousgeometric planning of robot motions. In particular, planning manipulation tasksin complex 3D environments leads to a large number of costly geometric plannerqueries to verify the feasibility of considered actions and plan their motions. Toaddress this issue, we propose Geometric Reasoning Networks (GRN), a graphneural network (GNN)-based model for action and grasp feasibility prediction,designed to significantly reduce the dependency on the geometric planner. More-over, we introduce two key interpretability mechanisms: inverse kinematics (IK)feasibility prediction and grasp obstruction (GO) estimation. These modules notonly improve feasibility predictions accuracy, but also explain why certain actionsor grasps are infeasible, thus allowing a more efficient search for a feasible solu-tion. Through extensive experimental results, we show that our model outperformsstate-of-the-art methods, while maintaining generalizability to more complex en-vironments, diverse object shapes, multi-robot settings, and real-world robots
Operando Gravimetric and Energy Loss Analysis of Na 3 V 2 (PO 4 ) 2 F 3 composite films by EQCM-D
No full textInternational audienceThe ever-growing need for energy storage requires new technologies to meet the increasing demands. In this context, Sodium-ion (Na-ion) batteries have emerged as a potential complementary technology to Lithium-ion batteries. Among other materials, Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) is a promising cathode for Na-ion batteries due to its high operating voltage and good energy density. In order to further characterize the (dis)charge behavior of NVPF, the electrochemical quartz microbalance with dissipation monitoring (EQCM-D) was employed to track both the frequency changes and dissipative losses at electrode/electrolyte interface. The</div
Évaluation de l’anosognosie et ses enjeux dans la maladie d’Alzheimer
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LapisGS: Layered Progressive 3D Gaussian Splatting for Adaptive Streaming.
No full textInternational audienceThe rise of Extended Reality (XR) requires efficient streaming of 3D online worlds, challenging current 3DGS representations to adapt to bandwidth-constrained environments. This paper proposes LapisGS, a layered 3DGS that supports adaptive streaming and progressive rendering. Our method constructs a layered structure for cumulative representation, incorporates dynamic opacity optimization to maintain visual fidelity, and utilizes occupancy maps to efficiently manage Gaussian splats. This proposed model offers a progressive representation supporting a continuous rendering quality adapted for bandwidth-aware streaming. Extensive experiments validate the effectiveness of our approach in balancing visual fidelity with the compactness of the model, with up to 50.71% improvement in SSIM, 286.53% improvement in LPIPS with 23% of the original model size, and shows its potential for bandwidth-adapted 3D streaming and rendering applications
Alfvén waves at low magnetic Reynolds number: transitions between diffusion, dispersive Alfvén waves and nonlinear propagation
No full textInternational audienceWe seek the conditions in which Alfvén waves (AW) can be produced in laboratory-scale liquid metal experiments, i.e. at low magnetic Reynolds Number ( ). Alfvén waves are incompressible waves propagating along magnetic fields typically found in geophysical and astrophysical systems. Despite the high values of in these flows, AW can undergo high dissipation in thin regions, for example in the solar corona where anomalous heating occurs (Davila, Astrophys. J. , vol. 317, 1987, p. 514; Singh & Subramanian, Sol. Phys. , vol. 243, 2007, pp. 163–169). Understanding how AW dissipate energy and studying their nonlinear regime in controlled laboratory conditions may thus offer a convenient alternative to observations to understand these mechanisms at a fundamental level. Until now, however, only linear waves have been experimentally produced in liquid metals because of the large magnetic dissipation they undergo when and the conditions of their existence at low are not understood. To address these questions, we force AW with an alternating electric current in a liquid metal in a transverse magnetic field. We provide the first mathematical derivation of a wave-bearing extension of the usual low- magnetohydrodynamics (MHD) approximation to identify two linear regimes: the purely diffusive regime exists when , the ratio of the oscillation period to the time scale of diffusive two-dimensionalisation by the Lorentz force, is small; the propagative regime is governed by the ratio of the forcing period to the AW propagation time scale, which we call the Jameson number after (Jameson, J. Fluid Mech. , vol. 19, issue 4, 1964, pp. 513–527). In this regime, AW are dissipative and dispersive as they propagate more slowly where transverse velocity gradients are higher. Both regimes are recovered in the FlowCube experiment (Pothérat & Klein, J. Fluid Mech. , vol. 761, 2014, pp. 168–205), in excellent agreement with the model up to but near the resonance, high amplitude waves become clearly nonlinear. Hence, in electrically driving AW, we identified the purely diffusive MHD regime, the regime where linear, dispersive AW propagate, and the regime of nonlinear propagation
Non-geodesic filament winding: Derivation process and resolution of a pair of ordinary differential equations in arc length based on vector projection
No full textInternational audienceNon-geodesic filament winding allows the manufacturing of various surfaces of revolution, including those once considered unsuitable for this process, such as Gaussian depressions (i.e., concavities), through numerical solutions of standard path equations without the need for ingenious workarounds. In this context, one of these mathematical models is thoroughly examined. It consists of an ordinary differential equation in arc length that has been exclusively applied to cylindrical geometries. The initial derivation technique is repeated with the aim of reformulating it in a more general manner, using intrinsic differential geometry concepts. As a result, a second equation, similar to the desired one but slightly more complex, is obtained. To verify its validity through comparison with the first equation, each is restated as a system of two differential equations that define the position of the path points of the fiber reinforcement, with the aid of cylindrical coordinates. Three geometries are chosen to validate the numerical solutions: a right circular cylinder, an exponential function that produces an axisymmetric Gaussian depression, and a third-degree polynomial that outlines a divergent nozzle. The solutions show that both systems of equations yield stable, predictable, and conventional results for all geometries, systems, and solving strategies. When the resolution is “forward” (i.e., the independent variable is the winding angle, the process is more elaborate. In contrast, it is straightforward when the resolution is “inverse”. Regarding the nozzle, comparison with an equation derived by another method, based on the geodesic and normal curvatures of the surface, reveals that the derived equation offers a broader solution range along the -axis and can handle higher friction coefficient values than those reported in the literature. Consequently, the newly derived equation demonstrates greater comprehensiveness and applicability. It is concluded that the derivation procedure is well-defined and that both equations are effective for advancing filament winding methods
Human Robot Interaction for Blind and Low Vision People: A Systematic Literature Review
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Impact of impurities on leakage current induced by High-Energy Density Pulsed Laser Annealing in Si diodes
No full textFor semiconductor device fabrication, Pulsed Laser Annealing (PLA) offers significant advantages over conventional thermal processes. Notably, it can provide ultrafast (~ns) and high temperature profiles (>1000°C). When the maximum temperature exceeds the melting point, a solid-liquid phase transition is observed, immediately followed by rapid recrystallization. This unique annealing mechanism gives raises questions about dopant diffusion and residual defects, in not only in the recrystallized region, but also just below it. As power devices require micrometer-sized junctions, high laser energy densities are needed, which were proved to promote the incorporation of complex impurities from the surface and the creation of defects at the liquid/solid interface. This paper reports on the impact of laser annealing at high energy densities (up to 8.0 J/cm²) on the leakage current, using Schottky and PN diodes, and DLTS measurements. Various laser annealing conditions were used: energy densities between 1.7 and 8.0 J/cm² with 1 to 10 pulses. Our results suggest that the liquid and solid solubility of vacancies in silicon are fixed by the maximum temperature reached, so to the energy density. Increasing the number of laser pulses allows, not only to reach this maximum vacancy concentration but also to promote their diffusion towards the surface. Concomitantly, the in-diffusion of complex impurities inside the melted region allows the coupling between both defect types to create trap centers, responsible for the degradation of the leakage current
How do choreographers construct movement through language ? A deconstruction of contemporary dance motion instructions
No full textInternational audienceThis paper considers 1200 instructions uttered by four French choreographers during four contemporary dance classes. The analysis of the multimodal corpus (10348 words) relies on semantic, syntactic, referential and functional parameters (Talmy 1983; Vandeloise 1986; Kleiber 1997) dealing with the nature of the entities involved (Aurnague et al. 2007), the semantics of verbs of motion (Aurnague 2011) and the manner component (Stosic 2019). Since contemporary dance movements are the original creation of choreographers, language lacks suitable lexical means for explaining them. Choreographers thus need to employ other linguistic strategies to give instructions to dancers. The main purpose of this work is to bring to light some aspects of motion event description that are necessary to convey the originality of dance movements