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Quaternion-Based Vision-Transformer for Polycrystalline EBSD Scans Pre-Trained on Large-Scale Synthetic Data
No full textInternational audienceDimensionality reduction is crucial in materials science for extracting patterns from high-dimensional data. This is vital for optimizing material design spaces by cutting computational complexity and for integrating diverse data sources for advanced anomaly detection, identifying structural or functional material deviations. Traditional convolutional autoencoders focus on local features, failing to capture global contextual information essential for predicting material behavior under stress, where overall material properties, grain orientations, morphologies and sizes are key. To address this, a Quaternion-Based Vision Transformer Masked Autoencoder (ViT-MAE) is proposed for polycrystalline materials. This model processes quaternion-valued EBSD orientation maps with a 65% masking ratio, capturing both local and global microstructural features efficiently. Pre-trained on synthetic data using self-supervision, the model achieves robust generalization on real-world EBSD scans by minimizing a misorientation loss function on the quaternion manifold. This work lays the groundwork for advanced multimodal data analysis in materials science, offering an open dataset and pre-trained vision-transformer weights. The goal is to provide a reliable latent space for EBSD orientation maps, advancing future multimodal characterization through latent space merging
Unraveling droplet drying kinetics under electric fields: A study on moisture content and evaporative flux profiles
No full textInternational audienceThis study investigates the influence of electric fields (EF) on the drying kinetics and evaporative flux of CuSO4.5H2O aqueous droplets at different solid contents. The drying behavior of pendant droplets was examined under both convective and diffusive conditions with varying EF intensities. The results indicate that the EF increases the surface area of the pendant droplet during both drying scenarios. In diffusive drying, the drying kinetic is different with and without EF. Indeed, the EF reduces moisture removal and evaporative flux in the early stages for highly concentrated droplets having high response to the electric field. However, as the droplet dries, the moisture removal rate and evaporative flux increase and converges to constant values, a trend observed under no-field conditions. In convective drying, the application of an electric field maintained a constant moisture removal rate until the droplet had lost 30 % of its water content, while in the no-field conditions this rate decreased up to 25 % as the drying progresses until the same water loss. Furthermore, when the electric field is applied, the evaporative flux increases with the drying time to reach constant values with the drying time. As a conclusion, this work uniquely combines pendant droplet drying under controlled dying conditions and high electric fields with a real time mass measurement and image-based surface area and deformation tracking, providing experimental access to electrohydrodynamic evaporation fluxes not previously reported in literature
Développement de mousses thermoplastiques réactives pour applications dans panneaux sandwich multifonctionnels
No full textInternational audienceLes panneaux sandwich multifonctionnels sont une classe de matériaux composites qui permettent d'intégrer des fonctions secondaires dans une structure porteuse. L'isolation acoustique ou encore la résistance à l'impact sont des propriétés fortement dépendantes des matériaux d'âme et plus particulièrement de leur microstructure. Afin de développer des nouvelles solutions plus respectueuses de l'environnement d'un point de vue du cycle de vie, cette étude propose d'explorer une technique de moussage novatrice pour obtenir des matériaux d'âme à partir d'une résine thermoplastique réactive Elium ® C195E. L'idée de base consiste à exploiter le teneur élevé du monomère méthacrylate de méthyl (MMA) dans le mélange réactif (75-80%), sa faible température d'ébullition (101°C), ainsi que la forte réactivité après mélange du système pour obtenir une mousse thermoplastique à faible densité. Les premiers résultats sont encourageants et ont permis d'obtenir plusieurs échantillons dans un moule fermé avec une bonne stabilité dimensionnelle. La microstructure observée après enrobage et polissage reste assez hétérogène, avec des pores de grosses dimensions d'environ 2 mm. Les prochaines campagnes d'essais mécaniques, acoustiques et à la tour de chute permettront de déterminer les applications potentielles ainsi que de déligner des potentielles voies d'amélioration pour pouvoir intégrer ces matériaux d'âme dans des panneaux sandwich multifonctionnels
Catalytic conversion of spent coffee grounds into graphitic and nanotube biocarbon
No full textInternational audienceGraphitic biocarbon comprising of graphene-like shells, nanotube-like structures, spherical clusters of graphitic biocarbon encapsulated Fe, and amorphous biocarbon, were simultaneously synthesized from spent coffee grounds. The study investigated the influence of two distinct types of non-toxic, easily accessible metal catalysts on graphitization, and the evolution of the catalyst-impregnated biocarbon nanostructures with temperature. The findings show that using Ca as a catalyst produces a highly porous graphitic structure with a larger crystallite size (Lc = 14.38 nm) and nanotube-like structures that become denser with temperature, increasing in diameter from 58.48 nm at 1200 °C to 93.64 nm at 1800 °C. Conversely, Fe as catalyst produces non-porous graphitic structures with a smaller crystallite size (Lc = 4.06 nm). Notably, unlike previous literature reports, nanotube-like structures were observed only in Ca-catalyzed biocarbon, not in the Fe-catalyzed ones
De la réception des messages HL7 à une base de données PostgreSQL : Étude de cas au sein d’une clinique enBelgique
No full textInternational audiencetraiterdes messages au standard HL7 émis en temps réelpar différentes applications d’un système d’informationhospitalier afin de les intégrer dans une base de donnéesrelationnelle PostgreSQL. Afin d’optimiser l’interopérabilité,cette base de données a été développée pour alimenterun prototype de tableau de bord de pilotage del’activité hospitalière et synchroniser un jumeau numérique,permettant ainsi un suivi en temps réel des parcourspatients. L’approche proposée repose sur l’analysesyntaxique (parsing) des messages HL7 et leur stockagestructuré. Cette étude a été menée par une équipe multidisciplinairedans le cadre d’un laboratoire commun entrele Centre Génie Industriel, IMT Mines Albi et le CHCLiège en Belgique
Synthèse de dérivés flavonoïdes précurseurs de principes actifs pharmaceutiques par mécanochimie : un procédé éco-compatible (thèse sous embargo)
No full textFlavonoids are natural products known for their varied therapeutic activities: anticancer, antiparasitic, anti-inflammatory, antioxidant or antifungal. The reaction involving the conversion of 2'-hydroxychalcone to flavonol was first described in 1934 by Algar, Flynn and Oyamada (AFO). One method for synthesizing 2'-hydroxychalcones is the Claisen-Schmidt reaction involving aromatic ketone and aldehyde. Green synthesis processes are also attracting growing interest. Among these, mechanochemistry is one of the unconventional activation methods that can offset the use of solvents as part of a more environmentally-friendly chemistry. One challenge is to apply mechanochemistry to the synthesis of molecules of interest. The thesis includes a “pharmaceutical mechanochemistry” section describing our studies into the mechanochemical Claisen-Schmidt synthesis of seventeen 2'-hydroxychalcone derivatives and their biological activities as anti-melanoma, anti-malarial and anti-leishmanial agents. One compound showed very good anti-melanoma activity (IC50 = 24,7 µM) and 4 against leishmaniasis (IC50 = 1-6 µM). A successful approach to obtaining the two flavonols (AFO reaction) is also reported. The second part of the thesis is a “fundamental and comparative mechanistic approach” between mechanochemical and solution reactions for 2'-hydroxychalcone, showing a promising anticancer effect. The mechanochemical study was carried out with a Pulvérisette P0 vibrating mill (from Fritsch) and by a conventional route, in solution in methanol. Apparent kinetics were modeled to quantitatively describe the influence of operating parameters and grinding conditions. The impact of parameters such as: the effect of the material, the size and mass of the grinding balls, the granulometry of the reagents, the temperature and the reagents/base equivalents were studied. This analysis showed that the reaction in solution follows a kinetic law of apparent order equal to 2, whereas the mechanochemical reaction follows two different kinetic models depending on temperature: a model of apparent order 0 for temperatures above 30 °C and a model of apparent order 2 for temperatures below 30 °C. The apparent rate constants determined in the solid and liquid routes enabled us to determine the activation energy values for mechanochemistry, 54 kJ/mol for temperatures below 30 °C and 42 kJ/mol for temperatures above 30 °C, and for solution, 47 kJ/mol. Green chemistry indicators (energy consumption, E-factor, hazard coefficient) show that mechanochemistry applied to the Claisen-Schmidt reaction is a more ecological and sustainable process than the reaction carried out in solution. This project was supported by the Occitanie Region.Les flavonoïdes sont des produits naturels connus pour leurs activités thérapeutiques variées : anticancéreux, antiparasitaires, anti-inflammatoires, anti-oxydants, ou antifongiques. La réaction consistant en la conversion de la 2'-hydroxychalcone en flavonol a été décrite pour la première fois en 1934 par Algar, Flynn et Oyamada (AFO). Une des méthodes de synthèse des 2'-hydroxychalcones est la réaction de Claisen-Schmidt mettant en œuvre une cétone et un aldéhyde aromatiques. D'autre part, les procédés verts de synthèse suscitent un intérêt grandissant. Parmi ceux-ci, la mécanochimie est une des méthodes non conventionnelles d'activation qui permet de pallier l'utilisation de solvants dans le cadre d'une chimie plus respectueuse de l'environnement. Un défi à relever consiste à appliquer la mécanochimie à la synthèse de molécules d'intérêt. Ce travail de thèse comporte une partie « mécanochimie pharmaceutique » décrivant nos études concernant la synthèse par la réaction de Claisen-Schmidt en mécanochimie de dix-sept dérivés de 2'-hydroxychalcones et de leurs activités biologiques en tant que antimélanomes, antipaludiques, et antileishmaniennes. Un composé présente une très bonne activité antimélanome (IC50 = 24,7 µM) et 4 contre la leishmaniose (IC50 = 1-6 µM). Une approche réussie vers l'obtention des deux flavonols (réaction AFO) est aussi rapportée. La deuxième partie de la thèse est une « approche mécanistique fondamentale et comparative » entre réactions mécanochimique et en solution pour la 2'-hydroxychalcone présentant un effet anticancéreux prometteur. L'étude par mécanochimie a été effectuée avec un broyeur vibrant Pulvérisette P0 (de la société Fritsch) et par une voie classique, en solution dans du méthanol. Une modélisation des cinétiques apparentes a été effectuée pour décrire quantitativement l'influence des paramètres opératoires et des conditions de broyage. L'impact des paramètres tels que : l'effet du matériau, la taille et la masse des billes de broyage, la granulométrie des réactifs, la température, les équivalents réactifs/base, a été étudié. Cette analyse a montré que la réaction en solution suit une loi cinétique d'ordre apparent égal à 2 alors que la réaction mécanochimique suit deux modèles cinétiques différents selon la température : un modèle d'ordre apparent 0 pour des températures supérieures à 30 °C et un modèle d'ordre apparent 2 pour les températures inférieures à 30 °C. Les constantes de vitesse apparentes déterminées en voies solide et liquide, nous ont permis de déterminer les valeurs d'énergie d'activation par mécanochimie, 54 kJ/mol pour les températures inférieures à 30 °C et 42 kJ/mol pour les températures supérieures à 30 °C, et en solution, 47 kJ/mol. Les indicateurs de chimie verte (consommation énergétique, E-facteur, coefficient de danger) montrent que la mécanochimie appliquée à la réaction de Claisen-Schmidt est un procédé plus écologique et durable que la réaction menée en solution. Ce projet a bénéficié d'un soutien de la Région Occitanie
Contribution of Raman analysis on tribological study of PEEK reinforced with micro or nano SiC particles
No full textInternational audienceThis study examines the tribological behavior of polyetheretherketone (PEEK) composites reinforced with silicon carbide (SiC) particles of varying sizes and concentrations. The composites, filled with both nano- and micro-sized SiC particles at different loadings (2.5%, 5%, 7.5%, and 10%), were evaluated for their wear resistance and friction properties using a ball-on-plate tribometer. Raman spectroscopy was employed to track crystallinity changes in the PEEK matrix within the wear tracks, revealing significant amorphization in high-stress regions, especially with higher SiC content.The findings show that nano-sized SiC particles provide superior reduced friction compared to their micro-sized counterparts, with optimal performance at 5–7.5% filler content. Nano-sized SiC particles enhance tribological performance by reducing friction while maintaining structural integrity in high-performance applications. However, higher SiC content led to increased wear in both micro- or nano-reinforced composites due to the instability of the wear debris. The study emphasizes the importance of particle size and filler content in improving tribological properties and suggests that further investigation into the mechanisms of wear and molecular disorientation could enhance the performance of PEEK-SiC composites
Low-temperature Highly Graphitized Porous Biomass-based Carbon as an Efficient and Stable Electrode for Lithium-ion Batteries and Supercapacitors
No full textInternational audienceGraphite is a widely used fossil material valued for its versatility, thanks to its excellent thermal and electrical conductivity as well as high chemical stability. Producing graphitic carbon from biomass offers a promising alternative to fossil graphite, but the process requires extremely high temperatures—up to 3000 °C—leading to significant energy consumption. In this work, we report a greener and more sustainable low-temperature method (900°C) for the synthesis of highly graphitized biomass carbon using pure boron as a catalyst and logging residues (LR) as a carbon source. The work focuses on the correlation between the structural transformation of the precursors into graphitic carbon and their corresponding electrochemical characteristics as electrodes for lithium-ion batteries (LIBs) and supercapacitors. The carbons were prepared in two steps, i.e., carbonization at 500°C with boron, followed by activation with KOH at 900°C. A control carbon, produced using the same method but without boron, was used for comparison. The physicochemical characterization results demonstrated the successful graphitization of the LR-based carbon. In addition, the carbon materials exhibited highly porous structures with specific surface areas (BET) of 2645 m2 g-1 for the boron-treated carbon (BCLR), and 3141 m2 g-1 for the control carbon (CLR). The CLR and BCLR electrodes tested in LIBs delivered specific capacities of 386 and 505 mAh g-1 at a 1 C rate at the end of 200 cycles, respectively. CLR and BCLR electrodes were also tested for supercapacitors, delivering specific capacitances of 87 and 144 F g-1 at a current rate of 1 A g-1, respectively. This work opens a gateway for a straightforward and cost-effective synthesis method for scaling up biomass-based carbon electrodes for LIBs and supercapacitors, facilitating sustainable precursors and an industrially viable approac
Control of retained austenite stability during the heat treatment of the high performance steel Ferrium® M54®
No full textInternational audienceFerrium® M54® ultra-high-strength steel is an excellent candidate for landing gear applications due to its balance of UTS, KIC, and KISCC properties, which is among the best compared to steels currently in use. The tensile strength of Ferrium® M54® at room temperature is mainly provided by the martensitic structure formed during quenching and by the precipitation of molybdenum M2C carbides during tempering. However, a significant amount of retained austenite may remain after heat treatment. This study demonstrates that both the temperature and the delay between quenching and cryogenic treatment are critical parameters. Specifically, carbon diffusion during this period, even at room temperature, contributes to stabilizing the retained austenite. Austenite stabilization is modelled using the Johnson-Mehl-Avrami-Kolmogorov law to determine the maximum allowable dwell time between quenching and cryogenic treatment. This important finding helps in stabilizing the yield strength and preventing the transformation of retained austenite into fresh martensite under load
Modeling cascading effects in collaborative systems: a formal risk interdependency framework
No full textInternational audiencePurpose -This paper introduces a formal risk interdependency framework to model cascading effects in collaborative systems. By characterizing risk causal chains and propagation chains, the framework aims to provide decision-makers with a structured tool to systematically identify, analyze, and prevent cascading risks in interconnected networks.Design/methodology/approach -The framework, named the danger-risk-consequence chain, defines core componentsdanger, stake, risk, condition, and consequencealongside their causal and propagation relationships, which form the basis for risk characterization. The framework is applied through a use case in the construction supply chain to demonstrate its capacity to model cascading risks.Findings -The framework uncovers risk propagation chains that lead to cascading effects and formalizes the state evolution of these effects within collaborative systems. Through the use case, it demonstrates practical value by enabling stakeholders to visualize interrelated risks, detect vulnerabilities early, and implement targeted mitigation measures to enhance resilience against cascading disruptions.Originality/value -This study presents a novel approach to modeling cascading effects by integrating risk causality and propagation into a formalized framework. In contrast to previous research, which offers static risk definitions for risk characterization, this framework contributes to risk management theory by providing a structured method for understanding and modeling interdependencies.</div