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Simulation of shockless spalling fragmentation using the Discrete Element Method (DEM)
No full textInternational audienceIn the present study a Discrete Element Method (DEM) is considered to model the dynamic behaviour and fragmentation mechanisms of alumina ceramic under high strain-rate shockless loading. GEPI (high-pulsed power) spalling experiments are simulated. The DEM allows to take into account the accurate propagation and interaction of stress waves within the samples upon calibration of microscopic bond parameters. The results indicate that a standard failure criterion can effectively represent the spalling phenomenon, though discrepancies with experimental data increase at higher strain rates. To address this, the study combines the DEM approach with a damage law, specifically the first and second order Kachanov damage law, tomodel crack initiation and propagation. Comparative analysis with experimental rear face velocity profiles validates the approach. The strain-rate sensitivity of the present DEM model is explored using loading pulses of increasing intensity that induce different strain-rate levels. This research demonstrates that the DEM approach can effectively model dynamic behaviour in brittle solids leading to a multiple fragmentation sensitive to the strain rate
Le cas des créoles français : mutualisation des ressources pour des dialectes apparentés
No full textInternational audienceCet article montre comment on peut envisager la mutualisation de ressources linguistiques, en factorisant des éléments de description de la syntaxe et du lexique, dans le cas de dialectes apparentés, dans le but de déployer plus facilement des technologies linguistiques pour des langues peu dotées. Le cas présenté est celui des créoles à base française de Guyane, de Martinique et de Guadeloupe. Une mutualisation est possible avec le créole de Haïti, dialecte voisin, qui n'est pas à proprement parler une langue de France, mais possède une base plus riche de ressources linguistiques
Seismic wave interaction with buried cavity networks: Analytical modeling and resonance effects
No full textInternational audienceWe study the scattering of elastic waves by a periodic array of cavities buried in an elastic halfspace. This configuration is relevant in seismology, where shallow voids can locally amplify ground motion. Building on homogenized interface models developed for infinite media, we extend the approach to account for the presence of a stress-free surface. The resulting model yields an analytical solution to the 2D elastodynamic problem for incident longitudinal L and transverse T waves. A semi-analytical multimodal solution is used for validation. The analysis reveals the conditions under which resonances occur in the soil layer between the cavity tops and the surface, with particular emphasis on the low-frequency resonance that dominates in seismic contexts. The model identifies the key parameters governing resonance and provides insights into the transition from infinite to finite cavity arrays. It offers a simplified yet accurate framework for assessing site-specific seismic amplification.</div
Chamber Implant for Chronic Optical Recordings from the Cerebral Cortex of Marmosets
No full textInternational audienceBackground: Marmosets are becoming an increasingly important animal model in Neuroscience and optical approaches such as two-photon microscopy are expected to provide data significantly contributing to our understanding of the brain, especially when performed chronically.New Method: We describe a novel imaging chamber that provides an optical window onto the marmoset cerebral cortex over several months, together with the surgery needed for its implantation and that of an associated headpost. MRI data allow optimal positioning on the skull. The chamber is tightly inserted into a craniotomy and its sealing system combines a thread with a silicone elastomer minimizing infection risk and CSF leakage. Continuous contact between the window and the cortex delays tissue regrowth. Opening and sterile re-sealing are easy to perform whenever access to the cortex is needed.Results: Functional data from longitudinal two-photon imaging using genetically encoded fluorescent calcium sensors reveal high optical quality over months. We also demonstrate the feasibility of two-photon imaging of genetically encoded voltage sensors in the marmoset cortex in-vivo.</p
Indoor turbulent airflow modelling with a new integral buoyant wall function
No full textInternational audienc
Organizational Barriers to the Operator 4.0, Operator 5.0 and Human-Centricity Paradigms: A Mixed Methods Study
No full textInternational audienceThis study addresses the limitations associated with the adoption of Operator 4.0, Operator 5.0, and human-centricity within manufacturing environments. Specifically, it examines the organizational barriers to the implementation of Operator 4.0, Operator 5.0, and the human-centricity paradigms. The study employed a mixed method, two-step Qualitative → Quantitative design where qualitative data analysis was integrated with advanced AI-based text-mining techniques. The findings indicate that the successful implementation of human-centricity necessitates addressing some fundamental organizational barriers, particularly those related to leadership approaches, operational efficiency, and the cognitive load of the operator. The results reveal that the most significant barriers are management-related, suggesting that technological solutions alone are insufficient without corresponding human-centric cultural changes. The categorization of organizational barriers into strong, moderate, and weak provides insight into the systemic and individual challenges that hinder the transition to a human-centric organization and the transition towards Operator 5.0 with a focus on the human-centric part
Simultaneous speciation of iodine-, gadolinium-, and platinum-based pharmaceuticals by HILIC-ICP-MS and its application to wastewaters
No full textInternational audienceThe presence of contaminants in drinking water resources is a topic of great interest, yet certain types of compounds as pharmaceutical residues are still under-documented. These contaminants include organometallic or halogenated complexes such as cancerostatic platinum compounds (CPC), gadolinium-based contrast agents (GBCA) and iodine contrast media (ICM). Because of their increasing use in recent years, their concentrations in effluents and surface waters can now reach μg L−1 for iodine compounds and ng L−1 for platinum- or gadolinium-based compounds. This work aims to develop an analytical methodology for the simultaneous speciation of iodine-, platinum- and gadolinium-based complexes at ultratrace levels (∼ng L−1). Our developments focused on hydrophilic interaction chromatography (HILIC) coupled with ICP-MS to separate and quantify ten drug residues, including three iodine-, three platinum- and four gadolinium-complexes. Three HILIC stationary phases (two zwitterionic, i.e. phosphorylcholine and ammonium-sulfonic acid phases, and one silica charged phase) were compared under different mobile phase compositions (organic solvent percentage, salt concentration and pH). Dipole moment computations using density functional theory (DFT) were performed to refine our understanding of observed compounds complex separation in HILIC. Phosphorylcholine stationary phase with an acetonitrile gradient from 75 % to 50 % in 10 mmol L−1 ammonium formate aqueous solution was found best compromise to achieve the separation of the ten tested complexes. Achieved LODs for the various complexes were between 1 and 3 ng L−1 Gd, 3 and 17 ng L−1 Pt and 46 and 63 ng L−1 I. The developed method was applied to urban and hospital wastewaters. Two ICM (iohexol and iopamidol) and one GBCA (gadoterate) were quantified while no CPC were detected. Concentration of gadoterate was of the same order in the two types of wastewaters, i.e. between 525 and 677 ng L−1 Gd. While iohexol was determined only in urban wastewaters at 30 μg L−1 I, the concentration of iopamidol in urban wastewater was about 30 times lower than in hospital wastewater (134 ng L−1 I)
Thermal stability of CoNiPtCuAu nanoalloys: from segregation to melting properties
No full textInternational audienceSegregation and melting properties of CoNiPt nanoparticles
La figure du bon dirigeant politique en Afrique de l'Ouest (Côte d'Ivoire-Ghana) : une lecture anthropologique de la légitimité du pouvoir politique
No full textThis article offers an anthropological reading of the figure of the good political leader in West Africa, based on ethnographic fieldwork conducted in Côte d’Ivoire and Ghana. Drawing on testimonies from ordinary citizens across diverse social backgrounds, it highlights a popular conception of leadership rooted in moral, communal, and relational values: listening, honesty, proximity, justice, transparency, and responsibility. Far from imported technocratic or institutional models, political legitimacy is understood here as a living relationship between rulers and the ruled, anchored in local practices and cultural references (kankéléntigui, téléniya, tchiantigui). The article underscores the gap between this popular ideal and current political realities marked by corruption, authoritarianism, and personalization of power. It concludes by proposing ethical pathways for leadership renewal in Africa, based on citizen participation, accountability, inclusion, and a synthesis between African heritage and political modernity.Cet article propose une lecture anthropologique de la figure du bon dirigeant politique en Afrique de l'Ouest, à partir d'une enquête ethnographique menée en Côte d'Ivoire et au Ghana. À travers les témoignages de citoyens ordinaires issus de milieux sociaux variés, il met en lumière une conception populaire du leadership fondée sur des valeurs morales, communautaires et relationnelles : écoute, honnêteté, proximité, justice, transparence et responsabilité. Loin des modèles technocratiques ou institutionnels importés, la légitimité politique est ici pensée comme une relation vivante entre gouvernants et gouvernés, enracinée dans les pratiques locales et les référents culturels (kankéléntigui, téléniya, tchiantigui). L'article souligne le contraste entre cet idéal populaire et les pratiques politiques actuelles marquées par la corruption, l'autoritarisme et la personnalisation du pouvoir. Il propose enfin des pistes de refondation éthique du leadership africain, fondées sur la participation citoyenne, la redevabilité, l'inclusion et la synthèse entre héritage africain et modernité politique