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Ionic liquid and organosolv pretreatments of horse manure: impact on lignin telomerization by organometallic catalysis and methanization
No full textInternational audienceTo deal with the high lignin content of horse manure in the methanization process, eco-fractionation and chemical modification strategies of lignin have been proposed, opening up prospects for new lignin-based thermoplastic materials. Firstly, a strategy inspired by the biochemical pathway and based on ionic liquid pretreatment, with appropriate recyclability and biodegradability characteristics, was implemented. A sugar-enriched fraction was recovered after enzymatic hydrolysis and a lignin-enriched fraction was isolated (80% w/w). The second strategy was an organosolv process, using the easily biodegradable 2-methyltetrahydrofurane-3-one, allowing selective extraction of a lignin-enriched fraction (> 80% w/w almost sugar-free) and a partially delignified sugar solid fraction. H/G/S ratios and aryl-ether linkages showed little difference for the two isolated lignins, which may be responsible for the more successful palladium-catalyzed telomerization of 1,3-butadiene on the phenolic and carboxylic hydroxyls of organosolv lignin. Whatever the strategy used, carbohydrate fractions showed competitive biochemical methane potential for methanization
Silk foams with metallic nanoparticles as scaffolds for soft tissue regeneration
No full textInternational audienceTissue regeneration can be achieved by providing endogenous cells with a biomaterial scaffold that supports their adhesion and proliferation, as well as the synthesis and deposition of an extracellular matrix (ECM). In this work, silk fibroin protein foams were formed by lyophilization to generate tissue engineering scaffolds. Three types of medically relevant nanoparticles (NPs) (iron oxide, gold and silver) were added to this biomaterial to assess the ability of silk foams to be functionalized with these NPs. The structural and mechanical properties of the foams with and without the NPs were suitable for tissue support. The in vitro cytocompatibility of the scaffolds was confirmed according to the ISO 10993 guidelines. The biocompatibility of the scaffolds was investigated by assessing inflammation and endogenous cell colonization in a mouse subcutaneous model These in vivo experiments demonstrated a loss of acute inflammation and the absence of chronic inflammation in the grafted animals. The obtained results show that silk foams are good candidates for supporting soft tissue regeneration with the additional possibility of functionalization with NPs
Contributions à l'atténuation des interférences électromagnétiques par commande rapprochée des transistors IGBT : une nouvelle approche du profil de paliers du courant de grille et une nouvelle figure de mérite à des fins d’évaluation
No full textIn power electronics, the design of power converters has always faced the need to reduce components size and weight, while at the same time seeking to improve efficiency. Increasing switching frequency and reducing switching times are two effective means of achieving these objectives, but they are coming with an increase in electromagnetic interference (EMI). Indeed, signals with fast switching (rising and falling) edges contain high-frequency (HF) components that can be propagated in a conducted and/or radiated manner, affecting neighbouring systems or even the power converter itself. In order to satisfy electromagnetic compatibility constraints, filters and shielding can be used, but this offsets the benefits initially expected from the converter frequency rise, as well as its overall cost. Another possible approach is to act at the source and, within this framework, this study is focused on MOSFET or IGBT transistors only. For such components, the switching edges are strongly determined by the charge injected into the gate of the transistor by the driver. As a result, the level of EMI disturbance can be controlled by the latter. And this is not limited to simply slowing down switching, which would have a negative impact on switching losses, but rather to deeply shape the rising and falling edges. Indeed, it has been theoretically proven that, for a given switching time, the optimal shape of the switching pattern function to mitigate the HF disturbances is Gaussian. The aim of this thesis is to develop an IGBT gate drive technique that comes close to this optimum condition. This technique is based on a current step profile (CSP) controlling the various stages of gate charging, exploiting current step amplitudes and their application times as degrees of freedom to achieve this objective. Its implementation uses a FPGA-based voltage-controlled current source. Furthermore, in order to validate the obtained results (both in simulation and experimentally), a new figure of merit (FOM) based on the Heisenberg-Gabor uncertainty principle is presented. It can be applied not only to theoretical reference signals, but also to any experimental results that can then be quantitatively characterized with respect to this EMI criterion. Finally, the proposed gate drive technique has been compared experimentally with a common commercial driver (IR2110) and with another technique of switching edge active control, known in the literature as "Control Around Threshold Voltage" (CATS in French).En électronique de puissance, la conception des convertisseurs de puissance a toujours été confrontée à la nécessité de réduire la taille et le poids des composants, tout en cherchant à améliorer le rendement. L'augmentation de la fréquence de commutation et la réduction des temps de commutation sont deux moyens efficaces pour atteindre ces objectifs, mais ils s’accompagnent d’une augmentation des interférences électromagnétiques (EMI). En effet, les signaux présentant des fronts de commutation (montée et descente) rapides contiennent des composantes haute fréquence (HF) susceptibles de se propager de manière conduite et/ou rayonnée, affectant les systèmes voisins ou même le convertisseur de puissance lui-même. Afin de satisfaire les contraintes de compatibilité électromagnétique, des filtres et des blindages peuvent être utilisés. Toutefois, cela annule les avantages initialement attendus de l'augmentation de la fréquence du convertisseur, tout en augmentant son coût global. Une autre approche possible consiste à agir à la source. Dans ce cadre, cette étude se concentre uniquement sur les transistors MOSFET ou IGBT. Pour ces composants, les fronts de commutation sont fortement déterminés par la charge injectée dans la grille du transistor par la commande rapprochée. Par conséquent, le niveau de perturbation EMI peut être contrôlé par ce dernier. Et cela ne se limite pas à un simple ralentissement de la commutation, qui aurait un impact négatif sur les pertes de commutation, mais vise plutôt à façonner en profondeur les fronts de montée et de descente. En effet, il a été théoriquement démontré que, pour un temps de commutation donné, la forme optimale de la fonction de commutation permettant d’atténuer les perturbations HF est gaussienne. L’objectif de cette thèse est de développer une technique de commande de grille d'IGBT qui se rapproche de cette condition optimale. Cette technique repose sur un profil de courant en paliers (Current Step Profile - CSP) contrôlant les différentes étapes de charge de la grille, en exploitant les amplitudes des paliers de courant et leurs temps d’application comme degrés de liberté pour atteindre cet objectif. Son implémentation utilise une source de courant contrôlée en tension à base de FPGA. De plus, afin de valider les résultats obtenus (à la fois en simulation et expérimentalement), une nouvelle figure de mérite (FOM) basée sur le principe d’incertitude de Heisenberg-Gabor est présentée. Elle peut être appliquée non seulement aux signaux de référence théoriques, mais aussi à tout résultat expérimental pouvant alors être caractérisé quantitativement selon ce critère EMI. Enfin, la technique de commande de grille proposée a été comparée expérimentalement à un driver commercial courant (IR2110) ainsi qu'à une autre technique de contrôle actif des fronts de commutation, connue dans la littérature sous le nom de "Commande Autour de la Tension de Seuil" (CATS en français
Accounting for the size effect in modeling the behavior of nanocomposite materials
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Efficient Heuristic to Solve the Multi-Pickup and Delivery Problem with Time Windows
No full textInternational audienceThis paper addresses the Multi-Pickup and Delivery Problem with Time Windows (MPDPTW), an extension of the well-known Pickup and Delivery Problem (PDP). Unlike the PDP, where each request involves one pickup and one delivery, the MPDPTW involves multiple pickups from different locations for a single delivery point. The objective is to minimize logistics costs while respecting time constraints. In this paper, we propose an efficient heuristic that relies on an advanced construction operator that explicitly states precedence constraints to construct high-quality solutions. Experimental results on the MPDPTW benchmark demonstrate that our approach matches all the best-known results from the existing literature and achieves a strict improvement in the relative gap for several instances, with an average enhancement of 0.2%. These results establish our method as the new state-of-the-art for solving the MPDPTW
Continuous Flow Synthesis of Furfuryl Ethers over Pd/C Catalysts via Reductive Etherification of Furfural in Ethanol
No full textInternational audienceFurfural has become one of the most promising building blocks directly derived from biomass. It can be transformed into numerous important biobased chemicals. Among them, furfuryl ethers such as furfuryl ethyl ether (FEE) and tetrahydrofurfuryl ethyl ether (THFEE) are considered to be attractive derivatives, notably as fuel components, due to their high stability and high octane numbers. Therefore, the production of furfuryl ethers from furfural via a hydrogenation route is an important academic and industrial challenge and requires the deployment of new catalytic processes under green and competitive reaction conditions. The existing processes are based on a two-step process combining hydrogenation and reaction with a strong Bronsted acid catalyst in batch conditions. For the first time, a continuous flow one-step process has been elaborated for the conversion of furfural directly into furfuryl ethers based on reductive etherification. The present work explores the catalytic performance in a continuous flow of commercial palladium catalysts supported on activated carbon for the catalytic reductive etherification of furfural with ethanol in the presence of trifluoroacetic acid. The chemical and engineering aspects, such as the mechanisms and reaction conditions, will be discussed
Discussion suite à la présentation du livre d'Anne Bellon, "L'Etat et la toile", éditions du Croquant, 2023
No full textDiscussion-débat dans le cadre des Entretiens de l'IRENEE, Université de Lorraine, NancyDepuis le développement public de l'internet jusqu'à l'emprise croissante des données, l'action de l'État est prise dans une toile d'échanges numériques toujours plus dense. Pour les institutions publiques, cette toile apparaît comme un espace de possibles à conquérir, un territoire « à civiliser », un monde présenté comme un opposé : libertaire, décentré, changeant et sans frontière, les caractéristiques de l'internet paraissent en contradiction avec les logiques même de l'action publique, dont l'objectif est de définir de manière durable et centralisée des outils de contrôle, d'organisation et de coercition. L'État peut-il rendre gouvernable cet univers complexe et emmêlé ? Comment a-t-il pris pied dans la toile ? Et quelles caractéristiques communes rassemblent cet ensemble disparate d'interventions liées au numérique ? L'ouvrage propose ainsi de démêler les liens entre l'État et la toile, des liens progressivement tissés, parfois défaits puis consolidés au grès des développement de l'internet et de la numérisation progressive des activités. Le récit qui en découle constitue la première histoire du traitement public de l'internet en France. Original par son ancrage national et son ampleur historique, il adopte un point de vue inédit non pas sur l'État mais depuis l'État, attentif aux rapports de forces qui le traversent et aux propriétés de celles et ceux qui l'incarnent. Il dévoile ainsi les rouages d'une révolution numérique dans l'État, conçue comme l'importation des logiques du monde de l'internet dans le secteur public, ainsi que leur traduction constante, voire leur subversion, dans les administrations
Advanced Facial Rehabilitation by Coupling Reinforcement Learning and Finite Element Modeling
No full textNational audienceThis study combines reinforcement learning with finite element modeling to facial motion learning. A novel modeling workflow for learning facial motion was developed using a physicallybased model of the face within the Artisynth modeling platform, reinforcement learning algorithms were used to simulate facial movements. After the training, the agent improved symmetry by approximately 89% for symmetry-oriented motion and closely matched experimental data for smileoriented motion. This novel approach integrates finite element simulations into the reinforcement learning process, offering advanced rehabilitation programs for such patients
Multi-criteria based components ranking for predictive maintenance: Application to electro-hydrogen generator
No full textPublished in Procedia CIRP 130:1110-1116, 2024International audienceIn order to improve the reliability and efficiency of a manufacturing system, it is essential to prioritize its components based on their importance and determine the most critical components for predictive maintenance considering multiple criteria. However, this can be a challenging task as different criteria may have varying degrees of importance and correlation with each other. To address this issue, a methodology has been proposed in this paper, which utilizes a multi-criteria decision process. The method involves the identification of specific evaluation criteria, such as maintenance frequency, duration, training requirements, inspection difficulty, component lifespan, and cost, in collaboration with maintenance experts. The developed methodology also allows considering the importance of criteria and the correlation between them. The proposed methodology is then applied to a real Electro-Hydrogen Generator (GeH2) to identify the most important components for predictive maintenance purposes. The results obtained are in line with expert judgments and practical considerations
La domestication de la sémiologie : proposition d’une organisation graphique du thesaurus semeioticus psychiatrique chez l’adulte
No full textNational audienceThis article proposes, for the first time, a graphic, visual, dynamic, hierarchical, and easily manipulated organization of all adult clinical manifestations terms, as proposed by the Association for the Teaching of Psychiatric Semiology (AESP). The aim is to make it a pedagogical and pragmatic tool, but also a reflective and critical one, for the use of psychiatric semiology in medicine. The proposal of this article lies more in a graphical formalization than in a clarification of the theoretical foundations of adult psychiatric semiology. The interest of the graphical visualization of the semiological apparatus in maintaining a critical approach and promoting the dynamic evolution of the Thesaurus Semeioticus is discussed, through its implications for the teaching of descriptive psychopathology language to students, and its implications for the necessary articulation with nosographic and psychopathological knowledge. The graphic visualization of the semiological apparatus can indeed help to clarify the vocabulary choices made by the psychiatric community and the possibilities for rigorous evolution in the light of scientific knowledge and clinical practice.Cet article propose pour la première fois, une organisation graphique, visuelle, dynamique, hiérarchisée, facilement manipulable de l’ensemble des termes sémiologiques chez l’adulte proposé par l’Association pour l’Enseignement de la Sémiologie Psychiatrique (AESP), afin d’en faire un outil pédagogique et pragmatique, mais aussi réflexif et critique, dans l’usage de la sémiologie psychiatrique en médecine. La proposition de cet article réside plus dans une formalisation graphique que dans une clarification des fondements théoriques de la sémiologie psychiatrique de l’adulte. L’intérêt de la visualisation graphique de l’appareil sémiologique pour maintenir une approche critique et une dynamique évolutive du thesaurus semeioticus parses effets sur l’enseignement de la langue sémiologique aux étudiants, et par ses effets sur l’articulation nécessaire avec les connaissances nosographiques et psychopathologiques sont discutés. La visualisation graphique de l’appareil sémiologique peut en effet permettre d'expliciter les choix de vocabulaire qui ont été réalisés par la communauté psychiatrique et les possibilités d’évolution rigoureuses au regard de savoirs scientifiques et de pratiques clinique