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Caloric curve and mechanism for emission of light charged particles in <math><mrow><mi>Xe</mi><mspace width="0.16em"/><mo>+</mo><mspace width="0.16em"/><mi>Sn</mi></mrow></math> collisions at 50 MeV/u
No full textInternational audienceCaloric curve for quasiprojectile (QP) particles is investigated, using the INDRA data set of Xe+Sn at 50 MeV/u. A constant pressure condition is applied, approximated by the isotropic expansion of the QP source with a constant velocity, but neither limiting temperature nor backbending behavior is observed in the extracted caloric curves. The extracted caloric curves follow a theoretical curve from the Fermi gas model with a level density parameter of a=13. He3 and α particles show much higher temperature values than those of the Hydrogen isotopes. The dynamical origin of the high energy light charged particles in the QP source is investigated and it is found that they are associated with the intermediate mass fragment production at the midrapidity in midperipheral to peripheral collisions. This component likely washes away the characteristic features of the liquid-gas phase transition, such as limiting temperature and backbending behaviors, in the caloric curves extracted in this study
Analyse spatio-temporelle expérimentale et numérique de la dynamique de l'effet Portevin-Le Chatelier dans un superalliage à base de nickel
No full textInternational audienceThis study examines the Portevin-Le Chatelier (PLC) effect in the nickel-based superalloy Inconel 718 through a combined experimental-computational approach using statistical indicators from nonlinear dynamical systems theory. We develop a finite element model incorporating the Kubin-Estrin-McCormick constitutive law to capture Dynamic Strain Ageing effects, accounting for machine stiffness influence, and reproduce various dynamics under both hard and soft loading conditions. Statistical analysis reveals that machine stiffness significantly affects serration morphology and dynamics, influencing mean amplitudes, stress drop periods, and dynamical indicators such as the correlation dimension and Lyapunov exponents. Comparison of simulated and experimental stress time series demonstrates chaotic behaviour for type B and C serrations across all strain rates, with no evidence of self-organised criticality in experimental data. However, simulations predict self-organised criticality at high strain rates corresponding to type A bands, consistent with literature references. Statistical indicators reveal power-law behaviour for stress drop amplitudes as a function of strain rate, with critical exponents dependent on band type. Multifractal analysis shows that simulations overestimate complexity relative to experimental observations, suggesting the need for additional internal variables and finer-scale dynamics in modelling. Additionally, multifractal analysis of spatio-temporal diagrams reveals power-law distributions of plastic strain rates with consistent critical exponents across all strain rates, demonstrating its potential for characterising PLC spatio-temporal dynamics. Statistical, dynamical, and multifractal indicators show consistent correlations, collectively capturing transitions between serration regimes and serving as reliable quantitative metrics for characterising PLC dynamics. The analysis is finally applied to the spatio-temporal strain fields measured by digital image correlation. The results demonstrate the value of multi-indicator analysis for assessing the agreement between experiment and simulation and subsequently improving constitutive model parameter identification
QP-based impact momentum maximization for a hammering task by a humanoid robot
No full textInternational audienceHumanoid robots can offload repetitive, loadbearing operations that expose workers to cumulative joint stress. In this paper, we focus on a hammering task with our humanoid robot HRP-5P and we propose a method to hit a nail with a given impact for a desired hitting velocity based on Quadratic Programming and the maximization of both the effective mass of the robot and impact momentum. Moreover, we implement a 5 th order Bézier curve as the trajectory, which ensures smooth, jerk-bounded motions from any reachable initial pose.</div
Image-Guided Autonomous Robotic Surgery in the Context of Therapies Managed by Intelligent Digital Technologies: A Narrative Review
No full textInternational audienceThis narrative review aims to highlight and analyze the supervision of precision robotic surgical interventions. These are autonomous, closed-loop procedures, assisted by images and managed by intelligent digital tools. These administered procedures are designed to be safe and reliable, adhering to the principles of minimal invasiveness, precise positioning, and non-toxicity. Thus, a precision intervention uses non-ionizing imaging-assisted robotics, controlled by a precise positioning device, forming an autonomous procedure augmented by artificial intelligence tools and supervised by digital twins. This intelligent digital management procedure allows staff to plan, train, predict, and execute interventions under human supervision. Patient safety and staff efficiency are linked to non-ionizing imaging, minimal invasiveness through image guidance, and strict delimitation of the intervention zone through precise positioning. This study includes, successively, sections covering an introduction, therapeutic and surgical interventions, imaging strategies integrating diagnostic and assistance functions, intelligent digital tools including digital twins and artificial intelligence, image-guided procedures including autonomous and precision robotic surgical interventions increased by machine learning, as well as augmented healthcare monitoring, and a discussion and conclusions of the review. All topics addressed in this analysis are supported by examples from the literature
Exploring Higgs EFT in at High Luminosity LHC
No full textInternational audienceThe non-resonant production of a Higgs boson pair in association with a top-antitop quark pair () has only recently begun to be explored at the Large Hadron Collider (LHC) and provides a unique and largely uncharted probe of the top-Higgs sector, offering complementary sensitivity to the Higgs self-coupling and higher-dimensional interactions beyond the Standard Model. In this work, we present a detailed study of this process within the framework of Higgs Effective Field Theory (HEFT) at the High-Luminosity LHC (HL-LHC). A comparative analysis is performed using a traditional cut-based approach in the single-lepton channel and a multivariate parametric boosted decision tree method in both single-lepton and dilepton final states. We derive one- and two-parameter limits at 95% confidence level on the HEFT couplings , , , and . The projected bound on is weaker than current experimental constraints from dedicated Higgs-pair measurement; however, this coupling plays a critical role in shaping the multidimensional allowed parameter space. For the remaining HEFT couplings, where no direct experimental limits currently exist, our results provide the first sensitivity projections in the channel. Overall, this study demonstrates the strong potential of the production process to probe extended Higgs and top-quark interactions beyond the Standard Model through the exploitation of the data at the HL-LHC
Techno-economic evaluation of electronic component recovery for reuse from waste PCBs: advancing circular economy practices in automotive electronics
No full textInternational audienceAbstract The increasing volume of electronic waste (e-waste) and shortage of critical materials emphasize the need for sustainable management of end-of-life printed circuit boards (PCBs). This study explores the techno-economic feasibility of reusing electronic components (ECs) from discarded PCBs, particularly used in automotive applications. We developed a systematic process involving manual disassembling with hot air guns, followed by a three-stage sorting process involving size-based segregation, magnetic separation, and optical sorting through convolutional neural networks (CNNs). The CNN-based sorting achieved over 99% identification accuracy, and electrical testing confirmed 98% of the components as functional for reuse. Techno-economic analysis of a simulated EC recovery plant showed encouraging financial outcomes, proving profitable even with a conservative resale value of 5–20% of market prices. A techno-economic model for a recovery plant was developed based on bottom-up costing, incorporating disassembly rates, labor productivity, equipment costs, reverse logistics, and resale value assumptions to evaluate break-even time and scalability across geographic regions. The research proved the environmental and economic benefits of integrating EC reuse into circular economy practices, offering a scalable framework for sustainable e-waste management. Graphical Abstrac
New Structural Insights and High Temperature Phase Transitions in Bismuth and Lead Uranates
No full textInternational audienceDespite extensive implementation of uranium and its oxides throughout the nuclear fuel cycle, studies of the ternary uranate structures are limited. The Bi-U-O and Pb-U-O systems are at the forefront of recent scientific development in the context of the lead bismuth eutectic cooled fast reactors. Given the social importance and the gap in our understanding of the solid state and crystal chemistry of uranium oxides, and the development of modern robust crystallographic techniques, there is compelling reasoning to return to studying uranium oxides.Bi2UO6 is one of few known structures in the Bi-U-O system. Our investigation of the thermal response of Bi2UO6 has demonstrated the inclusion of superlattice reflections not previously reported [1], which we have linked to the formation of oxygen vacancies. Using high resolution synchrotron X-ray powder diffraction and Neutron Powder Diffraction (NPD) in combination with DFT studies from first principles, we have resolved a new cell and accurate structure for Bi2UO6, crystallising in space group P-3m1. PbUO4 is a well-known member of the Pb-U-O system with orthorhombic Pbcm symmetry as determined by single crystal X-ray diffraction.[2] Previous studies of the thermal response of PbUO4 conditions have revealed little structural changes [3], however our investigations have demonstrated the irreversible transformation of PbUO4 to an unreported fluorite-related phase, nominally ‘Pb2U2O7’. Using a combination of NPD and DFT calculations, we have resolved the structure of Pb2U2O7 as the orthorhombic pyrochlore in space group Imma.These findings contribute toward bridging the gap of understanding regarding the structures and response to external stimuli of some of the simplest uranium oxides. Establishing such knowledge of fundamental uranium chemistry has implications for both the nuclear and crystallographic fields. With further adoption of nuclear energy, there is a growing need for a better understanding in uranium chemistry to facilitate the safe handling and storage of spent nuclear fuels and potential alteration phases. As it follows, establishing a strong understanding of uranium crystal chemistry, exhibiting 5f electron chemistry, may provide unique insights relevant to functional material design, as is demonstrated by the interesting capabilities of thermally induced oxygen defect ordering not previously realised.[1] Koster, A.; Renaud, J.; Rieck, G. The crystal structures at 20 and 1000° C of bismuth uranate, Bi2UO6. Structural Science 1975, 31 (1), 127-131.[2] Cremers, T.; Eller, P.; Larson, E.; Rosenzweig, A. Single-crystal structure of lead uranate (VI). Crystal Structure Communications 1986, 42 (12), 1684-1685.[3] Popa, K.; Beneš, O.; Staicu, D.; Griveau, J.-C.; Colineau, E.; Raison, P.; Vigier, J.-F.; Pagliosa, G.; Sierig, M.; Vălu, O. Thermal properties of PbUO4 and Pb3UO6. Journal of Nuclear Materials 2016, 479, 189-19
A comprehensive catalogue of high-mass X-ray binaries in the Large Magellanic Cloud detected during the first eROSITA all-sky survey
No full textInternational audienceThe Magellanic Clouds, the closest star-forming galaxies to the Milky Way, offer an excellent environment to study high-mass X-ray binaries. While the Small Magellanic Cloud has been thoroughly investigated with over 120 systems identified, the Large Magellanic Cloud has lacked a complete survey due to its large angular size. Most prior studies targeted central or high-star-formation regions. The SRG/eROSITA all-sky surveys now enable a comprehensive coverage of the LMC, particularly due to its close vicinity to the south ecliptic pole. This work aims to improve our understanding of the HMXB population in the LMC by building a flux-limited catalogue. This allows us to compare sample properties with those of HMXB populations in other nearby galaxies. Using detections during the first eROSITA all-sky survey, we cross-matched X-ray positions with optical and infrared catalogues to identify candidate HMXBs. We assigned flags based on multi-wavelength follow-up observations and archival data, using properties of known LMC HMXBs. These flags defined confidence classes for our candidates. We detect sources down to X-ray luminosities of a few erg s, resulting in a catalogue of 53 objects, including 28 confirmed HMXBs and 21 new eROSITA detections. We identify several likely supergiant systems, including a candidate supergiant fast X-ray transient with phase-dependent flares. We find three Be stars with likely white dwarf companions. Two of the Be/WD candidates show steady luminosities across four eROSITA scans, unlike the post-nova states seen in the majority of previous Be/WD reports. Our catalogue is the first to cover the entire LMC since the ROSAT era, providing a basis for statistical population studies. Using the HMXB population, we estimate the LMC star-formation rate to be Myr, which is in agreement with other tracers
High Energy Emission from the Galactic Center
No full textInternational audienceThe center of the Galaxy is a prominent source in X-rays and gamma-rays. The study of its high-energy (HE) emission is crucial in understanding the physical phenomena taking place in this dense and extreme environment, where the closest supermassive black hole (SMBH) to us, Sgr A*, is lurking nearly invisible, today, in most of the energy spectrum. These phenomena are probably common to other galactic nuclei and may explain the feedback processes between nuclear regions and galaxies, so important for the overall evolution of the Universe. The Galactic center HE emission is very complex and consists of both thermal and non thermal radiation produced by compact and extended sources, surrounded by more diffuse components. All these objects and media are interacting with each other in the narrow and dense Central Molecular Zone (CMZ). Some of them also show relevant extensions towards the Galactic poles, indicating energetic outflows that seem to link the center to the recently observed large Galactic polar structures. In spite of the fundamental advances obtained in the last twenty five years with the most sensitive X-ray and gamma-ray observatories, several questions remain open to investigations. We review here the main observational results and the open issues on the high-energy diagnostics of the Galactic nuclear activity, focusing on processes that take place in the CMZ, and in particular discussing the role of the present and past SMBH activities in powering this region and possibly the whole Galaxy
Pourquoi la Chine devient-elle attractive pour les talents étrangers ?
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