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3D simulation of residual stresses induced by ElectroMagnetic pulse Peening process
No full textInternational audienceCompression techniques such as shot peening, laser shock peening, and water jet peening are commonly employed to induce residual compressive stresses in mechanical components. These residual stresses play a crucial role in preventing the initiation and propagation of cracks. An innovative method known as the ElectroMagnetic pulse Peening (EMP) process utilizes magnetic forces to introduce residual compressive stresses in mechanical components. The EMP process shares similarities with the ElectroMagnetic Forming (EMF) process, which has been extensively studied through numerical and experimental investigations. Existing numerical studies predominantly feature axisymmetric 2D simulations, with limited availability of 3D simulations due to numerical constraints regarding computing time and resources. Since the EMP process shares similarities with EMF, similar challenges arise with respect to computational resources and time. This paper presents an innovative approach for the 3D simulation of residual stresses induced by the EMP process, based on efficient 2D axisymmetric calculations of the electromagnetic fields. The main objective of this approach is to simulate the mechanical impact of electromagnetic pulses applied by sweeping a surface, in order to analyze the stress distribution in the overlapping regions. First, the 2D model used to simulate electromagnetic phenomena is presented, and the 2D-to-3D transfer technique developed is detailed for computing residual stresses in 3D. Subsequently, the validity of this approach is established through a comparative study between 2D and 3D mechanical results for a single electromagnetic pulse. Finally, a multiple-pulse simulation is conducted to investigate the effect of overlapping treatment regions on an AA6061 aluminum alloy. The outcomes of this study are discussed in terms of the residual stresses at the subsurface
A new lifetime measurement of the <math altimg="si3.svg"><mrow><mn>15</mn><mo linebreak="goodbreak">/</mo><msubsup><mn>2</mn><mn>1</mn><mo>−</mo></msubsup></mrow></math> octupole state in Pb
No full textInternational audienceA spectroscopic study of the 15/21− isomeric state in 209Pb has been performed to shed more light on the octupole phonons near the doubly-magic nucleus 208Pb. Populated by neutron-transfer reactions 208Pb(d, p)209Pb*, the de-exciting nuclei of interest were measured with the SFγNCS array, a versatile set-up comprising a silicon telescope and 60 NaI(Tl) detectors. Determined with particle-γ-ray coincidences, the branching ratio and multipolarity of the aimed γ-ray transition of the 15/21− state in 209Pb were found to be consistent with the literature. The state lifetime was precisely measured with the delayed coincidence method. The resulting reduced transition probability B(E3,15/21−→9/21+)=24.2(4) W.u. is an order of magnitude more precise than previously reported. An analysis in terms of the particle-octupole-vibration coupling model led to a reevaluation of the neutron E3 effective charge. This new experimental result on the lifetime of the 15/21− octupole state in 209Pb should help future investigations to constrain the nature of states in 207,208,209Pb
Biomechanical mapping of porcine dentin and branches with Brillouin confocal VIPA-based microscopy
No full textInternational audienc
Stop writing repetitive code! Scaffolding a semantic data access layer to abstract developers from semantic technologies
No full textInternational audienceSemantic web technologies are sometimes perceived as difficult to adopt and use, and when developing data-driven applications a significant portion of the overall effort involves the writing of data access code. We propose, therefore, a technique to automatically generate data access layer code from data in semantic formats, abstracting away from developers data querying concerns. We also explore its use inside the EHRI project in order to support cultural heritage institutions in publishing their data in a systematic and sustainable way and we compare it against other libraries covering a similar purpose by means of a subjective analysis and a quantitative performance evaluation. Our results show how their design choices affect the overall usability and ultimately the final performance when integrated in larger applications. As a result, we deliver some recommendations of use for each of the tools depending on the developers’ needs. Thus, we see this work as a first step in exploring the benefits that these libraries can provide in abstracting semantic technologies and, thereby, promoting their adoption for data-driven applications
Simulation numérique directe de la combustion d'une particule d'aluminium isolée sous divers environnements
No full textThe authors acknowledge the French Defense Agency for funding L.P.’s scholarship and CALMIP supercomputing centre in Toulouse (France) for providing us computational resources.International audienceThis study presents a comprehensive numerical investigation of single aluminum particle combustion under varying convective oxidizing flow conditions, using Direct Numerical Simulations. A three-dimensional, boundary-layer-resolved model is developed to capture the complex interplay of gas-phase chemistry, surface reactions, and multiphase transport phenomena. The model incorporates aluminum evaporation, aluminum suboxide reactions at the particle's surface, and alumina formation both on the surface and in the gas phase. It also introduces an original scheme to account for the dissolution of alumina into the molten particle, based on parameters derived from molecular dynamics simulations. The model was validated against experimental burn time data. The unsteady combustion of a 125 μm-aluminum particle in various flowing O2/N2 conditions is then investigated in terms of standoff flame distance, gas-phase temperature and chemistry, particle temperature and surface chemistry. The results demonstrate that gas-phase reactions remain the dominant source of heat release, although surface reactions, particularly under highly oxygenated environments, play a significant role in modulating local combustion kinetics. The formation of liquid alumina at the particle's surface, its partial dissolution into the molten aluminum, and the limited surface coverage even at high O2 concentrations highlight the importance of coupling surface chemistry with thermal transport. While this mathematical model successfully reproduces the main macroscopic characteristics such as flame temperature, burn time-radius relationship, gas-phase composition, and fluxes, some discrepancies appear near the particle surface, i.e. at the microscale. These deviations can be attributed to radiative heat transfer effects which are not considered or to an incomplete understanding of surface reactions
Improving DNA detection sensitivity for the white-bellied pangolin (Phataginus tricuspis) via digital PCR
No full textInternational audienc
« Gérard de Nerval, Célestin Nanteuil : “les stigmates éternels” du Romantisme »
No full textInternational audienceÉtudier parallèlement Nerval et Nanteuil revient à faire revivre le Romantisme de 1830, qui correspond à leurs années de jeunesse, et à en saisir l’éloignement mélancolique dans les décennies suivantes, alors que Nanteuil s’assagit et que Nerval donne à l’expérience poétique une intensité nouvelle. Nous étudions quelques œuvres marquant un point de contact précis entre l’écrivain et l’illustrateur, pour mieux souligner le moment de bascule, autour de 1850, entre Romantisme et modernité
Le renouvellement de la norme dans les villes médiévales : l’exemple du scripteur urbain
No full textInternational audienceThis article looks at how the concept of renewal can be applied to the norm, both in terms of its content in relation to its objective, and in terms of the producer of the norm, between permanence and (re)legitimisation in relation to the latter. The study shows that renewal applied to the norm is never sufficient in itself in medieval towns. Depending on the case, renewal takes the form of restarting, replacing, repeating, extending or reiterating.Cet article traite de la manière dont le concept de renouvellement peut être appliqué à la norme, à la fois sur son contenu par rapport à l’objectif de celle-ci et sur le producteur de la norme, entre permanence et (re)légitimation concernant ce dernier. L’étude démontre que le renouvellement appliqué à la norme n’est jamais suffisant en soi dans les villes médiévales. Il est alors nécessaire de le préciser ; le renouvellement se faisant selon les cas par recommencement, remplacement, répétition, prorogation ou réitération
Efficient Edge AI Learning with Equilibrium Propagation: A Practical Solution For Gradient Computation
No full textInternational audienceThe rapid growth of smart devices and sensors has led to an overwhelming increase in data generation, pushing current network infrastructure to its limits and threatening the scalability of cloud-based processing. Edge machine learning, which processes data locally on devices, presents a viable solution to reduce network load and latency. However, deploying deep learning at the edge remains difficult due to the limited memory and computational capacity of these devices which mostly precludes on-device/on-site training. Equilibrium propagation (EP) has emerged as a promising alternative to backpropagation, leveraging analog processing and device physics for energyefficient learning. Yet, its practical implementation is hindered by challenges such as voltage variations and the need for energyefficient circuits capable of gradient computation at a sufficient level of accuracy. Existing solutions rely on impractical idealized models. In this work, we introduce a novel method to address the problem of the wide dynamic range of the voltage variation to avoid the use of expensive low-noise amplifiers, and propose an innovative transistor-level switched-capacitor circuit to compute gradients in accordance with the EP rule. Additionally, our design supports batching, a key requirement for stable training that is often overlooked. We validate our approach on the MNIST dataset, demonstrating a practical, energy-efficient EP circuit that operates within real hardware constraints