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Morphological, chemical, thermal and mechanical analysis of doum fibers as potential reinforcement of polymer composites
No full textInternational audienceThe research article addresses, a novel natural cellulosic fiber namely Doum Palm Leaf Stalk Fibers (DPLSF) were extracted from Doum palm tree ( Chamaerops humilis L.) are rich in cellulose, relatively inexpensive, and readily available in Algeria. The characteristic analysis on morphological, physiochemical, thermal and mechanical proprieties of the extracted raw and treated DPLSF with 20% sodium bicarbonate at various times of treatment were exanimated by optical microscope and scanning electron microscopy (SEM), X-ray diffraction method (XRD), Fourier transform infrared (FTIR) spectroscopy, thermos gravimetric analysis (TGA/DTG), differential scanning calorimetry (DSC). The SEM micrographs of the longitudinal topographic surface of the DPLSF after chemical treatment with sodium bicarbonate at various times treatment indicated that the removed the waxy layer and impurities from surface and formed a roughened surface. XRD analysis further confirmed the treatment’s positive effect on the fibers, with the crystallinity index increasing from 71.43% to 81.03%. However, FTIR analysis showed minimal changes in the peak position and intensity of transmittance. The TGA/DTG results revealed a significant mass loss in treated DPLSF, while thermal stability improved from 290°C to 330°C. Additionally, we analyzed the mechanical tensile properties of the treated fibers and observed that fibers treated at 20% NaHCO 3 for 24 h exhibited the highest Young's modulus 8.63 GPa. To validate the experimental findings, we compared individual DPLSF results to a numerical simulation using ABAQUS code. This study underscores the potential of DPLSF as a sustainable and eco-friendly alternative to synthetic fibers, offering immense promise for diverse applications
Perméabilité gazeuse des polymères et composites à matrices organiques aux températures cryogéniques
No full textIn the current context of ecological transition, the field of aeronautical transport is committed to developing engines that are neutral in terms of greenhouse gas emissions. With an energy density three times that of fossil fuels, hydrogen is the ideal energy carrier for this transition. However, the need to optimize on-board energy density means that hydrogen has to be stored in its liquid form at 20K, and it is therefore critical to identify the materials best suited to these application constraints, which must be light, resistant to low temperatures and impermeable to this element with low steric hindrance. Recent initiatives in the space industry have shown that tanks made from organic matrix composites can be effective for cryogenic storage. With a weight saving of almost 40% compared to aluminum, these composite tanks offer real prospects for the aerospace industry. However, their tightness under cold conditions has received very little attention in the literature. The aim of the work presented in this manuscript is therefore to provide a better understanding of the mechanisms governing the permeability of organic matrix and carbon fiber polymers and composites between ambient temperature and the cryogenic range. The first part of this project focuses on the development of an apparatus capable of measuring precisely (to the ppm) the permeability of a materials between ambient temperature and 55 K in a controlled manner. Using this test method, unprecedented cryogenic permeability data was generated for various thermoplastics (PA, PE, PAEK, PVDF, PPS). By comparing polymers with a wide range of glass transition temperatures (Tg), it was possible to establish correlations between the physicochemical and morphological properties of materials and permeability. The results confirm that glass transition and crystallinity have a significant effect on permeability at both ambient and cold temperatures. But it also appears that the rigid amorphous phase (RAF) can affect the permeability of PAEKs. Other phenomena such as secondary transition have also been attributed to changes in gas solubilization properties in materials at high Tg. Regarding the tightness of composite materials, the tortuosity of diffusion paths caused by the presence of carbon fibers, which are tighter than matrices, was first analyzed. Finite element simulations were used to explore the effect of trans-crystallinity on tortuosity in a composite with a semi-crystalline thermoplastic matrix. Cryogenic cycles were then applied to a wide range of composite materials (with thermoplastic and thermosetting matrices, nano-charged or not) in order to assess their resistance to cracking and to observe changes in permeability as a function of material damage. It was shown that the addition of carbon nanofillers to the interplies improved the crack resistance of the composites without impacting the barrier properties of the material. The results obtained show that 8552 and M21E matrix composites have the best barrier properties, making them promising materials for the development of storage tanks.Dans le contexte de transition écologique actuel, le domaine du transport aéronautique s'est engagé dans le développement de motorisations neutres en émissions de gaz à effet de serre. Avec un taux massique énergétique trois fois supérieur à celui des énergies fossiles, l'hydrogène représente alors le vecteur énergétique idéal pour cette transition. Néanmoins, la nécessité d'optimiser la densité énergétique embarquée impose son stockage sous sa forme liquide à 20K, et il est donc primordial d'identifier les matériaux les plus adaptés à ces contraintes applicatives, à la fois légers, résistants à basse température et étanches à cet élément au faible encombrement stérique. Les initiatives récentes dans le domaine spatial ont démontré que les réservoirs en composites à matrices organiques pouvaient être performants pour le stockage cryogénique. Avec un gain de masse de près de 40% par rapport à l'utilisation d'aluminium, ces réservoirs en matériaux composites ouvrent de réelles perspectives dans le domaine aéronautique. Néanmoins, leur étanchéité à froid a très peu été abordée dans la littérature. Les travaux présentés dans ce manuscrit ont ainsi eu pour objectif d'apporter une meilleure compréhension des mécanismes gouvernant la perméabilité des polymères et des matériaux composites à matrice organique et à fibres de carbone entre la température ambiante et le domaine cryogénique. La première partie de ce projet est centrée sur le développement d'un instrument capable de mesurer précisément (au ppm près) la perméabilité d'un matériau entre la température ambiante et 55 K de manière contrôlée. Grâce à ce moyen d'essai, des données inédites de perméabilité cryogénique ont été générées pour différents thermoplastiques (PA, PE, PAEK, PVDF, PPS). La comparaison de polymères ayant des températures de transition vitreuse (Tg) très variées a permis d'établir des liens entre les propriétés physico-chimiques et morphologiques des matériaux et la perméabilité. Les résultats obtenus confirment le rôle majeur de la transition vitreuse et de la cristallinité sur la perméabilité à température ambiante comme à froid. Mais il apparaît également que la phase amorphe rigide (RAF) peut affecter la perméabilité des PAEK. D'autres phénomènes tels que la transition secondaire ont également été attribués à des changements de propriétés de solubilisation du gaz dans les matériaux à haute Tg. Concernant l'étude d'étanchéité des matériaux composites, la tortuosité des chemins de diffusion engendrée par la présence des fibres de carbone, plus étanches que les matrices, a tout d'abord été analysée. Des simulations par éléments finis ont permis d'explorer la piste de l'effet de la trans-cristallinité sur la tortuosité au sein d'un composite à matrice thermoplastique semi-cristalline. Puis, des cycles cryogéniques ont été appliqués à une large gamme de matériaux composites (à matrices thermoplastiques et thermodurcissables, nano-chargés ou non) dans le but d'évaluer leur résistance à la fissuration et d'observer l'évolution de la perméabilité en fonction de l'endommagement du matériau. Il a ainsi pu être montré que l'ajout de nanocharges de carbones aux inter plis permet d'améliorer la résistance à la fissuration des composites sans impacter les propriétés barrières du matériau. Les résultats obtenus montrent que les composites à matrice 8552 et M21E présentent les meilleures propriétés d'étanchéité, ce qui en fait des matériaux prometteurs pour le développement de réservoirs
Integrating social interaction within senselife framework
No full textPart 1: Empowering Vulnerable Populations Well-being through Collaborative NetworksInternational audienceAs the global elderly population continues to grow, social isolation emerges as a critical factor contributing to the incidence of frailty. This paper explores the integration of social interaction functionalities within the Senselife framework, a service recommendation platform designed for frailty prevention in older adults. We propose enhancements to Senselife that facilitate communitybuilding and social engagement through technology-driven interactions. By leveraging user-centered design, the paper discusses how enhanced social features can significantly improve the efficacy of our frailty prevention strategies, offering a holistic approach to elderly care. Our methodology includes the development of social interaction modules that encourage active participation and connectivity among elderly users, ultimately aiming to enhance their quality of life and reduce the risks associated with social isolation
Model-Based Artificial Intelligence Architecture for Digitizing Handwritten Medication Error Reports
No full textInternational audienceOptical Character Recognition (OCR) is extremely useful in various sectors for exploring massive archived data. This technology enables the digitization of printed and handwritten texts that are frequently present in the medical field. For instance, medication error (ME) reports were previously and still in some healthcare facilities written manually, this has led to the accumulation of numerous handwritten data that are unfortunately challenging to exploit. Their digitization through OCR allows extracting important data from these documents and using them to populate the database to implement future analysis techniques to optimize the medication error management process. This paper presents a transformer-based handwritten recognition architecture that employs the Transformer-Based Optical Character Recognition (TrOCR) model combined with image segmentation techniques. Although the TrOCR model provided by Microsoft performs reasonably well in handwritten recognition, it is limited to English text because its pretrained version was trained exclusively on English samples. This limitation is problematic for us, as our task involves digitizing French medication dictation errors. Additionally, its limitation to processing single-line text images impairs its ability to recognize paragraphs. To address these limitations, we will fine-tune the model on French handwritten data and integrate a single-line level segmentation technique, thereby overcoming these constraints. Therefore, the preliminary results from implementing our proposed architecture are promising for the digitization of medication error reports
Production de biocarbone graphénique en combinant carbonisation hydrothermale et pyrolyse solaire
No full textInternational audienc
A New Strategy in Modelling Sonochemical Reactors: Combining Acoustics with Heat and Mass Balances with Applications to Cavitating Viscous Fluids
No full textInternational audienc
New C4-FN and C4-FN mixture gas models as a common reference for users and equipment manufacturers
No full textInternational audienceGas mixtures of fluoronitriles (C4-FN) with CO2 or N2 and optional O2 addition are applied as a low global warming potential (GWP) alternative to SF6 in HV switchgear [1] [2]. From the thermodynamic point of view, these mixtures cannot be considered as ideal. However, accurate predictions of dew points and mass densities are important to define operating gas pressures, gas handling and condition monitoring during operation. Ideal gas assumption would lead to errors in dewpoint and mass density predictions, especially for mixtures with low C4-FN content of a few %-mol only. The application of real gas equations of state (EoS) is necessary, therefore, and those must be calibrated properly by the respective EoS parameters. This report summarizes reference dewpoint measurements performed in a specialized thermodynamic laboratory for relevant gas mixtures at typical operating conditions. A real gas EoS of the Peng-Robinson type [3] [4] has been calibrated with those experimental results by the adjustment of the so-called binary interaction parameters (BIP). Since the solution of real gas EoS demands for specialized equation solvers for finding the dewpoints, simplified equation systems in the format of polynomials have been derived to accomplish “straight forward” calculations with acceptable high accuracy. Those equations can be used as the actual reference for determining dew points and mass densities of gas mixtures containing C4-FN and CO2/O2 or N2/O2 without the need for specialized thermodynamic software. Guidance is given towards application for typical scenarios in high-voltage substations: operation of high-voltage equipment (mass density and dew point at low pressure); storage in gaseous state (dew point at medium pressure), storage in liquefied form (high pressure), and gas handling operations using supercritical or overheated state (target temperature)
Enabling Federated Interoperability in Enterprise Models with Artificial Intelligence and Simulation.
No full textInternational audienceEnterprise interoperability is crucial for modern companies survival and market competitiveness. Progress in this field has stalled due to a lack of suitable techniques and technology. However, the rise of generative AI and language models now enables automation of various interoperation processes. This vision paper reviews the limitations of previous interoperability methods and suggests enhancements through the use of language models and simulation
Que sont les CMC ?: Chapitre 1
No full textLivre issu de la première École thématique du groupement de recherche (GDR) du CNRS n°2065, intitulé : "Composites à Matrice Céramique : Caractérisation, Modélisation, Conception" ou "(CMC)"2, qui s'est tenue du 10 au 15 octobre 2021 à Hendaye.National audienc