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Sustainable Rural Mobility: Strategic Impact of Integrating Autonomous Lightweight Rail into Multimodal Networks
No full textRural intermodal transport plays a crucial role in enhancing regional connectivity, fostering economic growth, and promoting environmental sustainability. This paper introduces a methodology to evaluate the feasibility of autonomous lightweight rail systems in rural networks, illustrated through a case study in Occitanie, France. Leveraging a multimodal network flow model, we assess operational, environmental, and economic impacts, with a particular focus on the role of transshipment in optimizing transport flows. Our approach demonstrates the potential for reducing emissions, improving transport efficiency, and maximizing infrastructure utilization based on key performance metrics. A sensitivity analysis of strategic scenarios provides valuable insights for policymakers. This framework offers a pathway to sustainable and cost-effective rural mobility by balancing efficiency, environmental impact, and economic viability through optimized intermodal synergies
Synthesis of graphitic biocarbons from lignin fostered by concentrated solar energy
No full textInternational audienceThe approach aiming at replacing fossil-based carbons by graphitic biocarbon has gained momentum in applications from environmental remediation to battery electrodes and supercapacitors, reducing their environmental impact. To address biocarbon high production temperature and energy consumption, this work uses lignin, a renewable feedstock, and concentrated solar as a sustainable energy source. New insights into lignin’s graphitization mechanism using solar energy are provided. Graphene layers stacking appears as early as 1000 °C in solar carbonization. The structuration and reduction of amorphous carbon was further highlighted at 1400 °C and 1800 °C. At 2000 °C, high graphitic ( L a(XRD) ≈ 9.1 nm, d 002 = 0.3386 nm, 110 stacked layers) and turbostratic ( d 002 = 0.3593 nm, 5.5 stacked layers) phases are obtained, showing the structural heterogeneity of solar biocarbon. Contrariwise, conventional biocarbon from electrical heating was homogeneous with limited carbonization at 1800 °C ( L a(XRD) ≈ 3.8 nm, d 002 = 0.3600 nm, 4.4 stacked layers). Textural analysis of solar biocarbons showed aligned graphene layers whereas only random texture was observed on conventional samples. This work established that solar carbonization triggers and enhances graphene layers stacking and growth at lower temperatures whereas conventional carbonization allows the progressive apparition of short graphene layers before stacking and growth
A new strategy for modelling sonochemical reactors: Coupling of the non-linear Louisnard model with mass and heat transport equations with applications to cavitating viscous fluids
No full textInternational audienceIn this work, novel numerical models were developed and validated to offer new strategies in modelling sonochemical reactors. More specifically, in our original approach the non-linear Louisnard model was coupled with heat and mass transport equations to predict gradients in temperature and species concentration in a sonicated reactor. Additionally, a new operating window was investigated by modelling mixtures of increasing viscosity on both micro- and macroscale sonochemical effects. On the microscale, the effects of increasing viscosity on bubble dynamics were determined by solving the Keller-Miksis equation. Various cavitation threshold definitions were evaluated. The bubble collapse temperature was determined for all investigated mixtures and the energy dissipation of a single bubble was calculated. On the macroscale, different acoustic attenuation models were compared accounting for either linear or non-linear equations. Specifically, viscous losses were implemented in the non-linear Louisnard model, and model predictions were validated against experimental data. The model was able to predict multiple zones of cavitation in the reactor, as observed experimentally, and to estimate the dissipated energy for the different mixtures. Moreover, it was demonstrated that the cavitation-based attenuation dominates the other dissipation phenomena even for the most viscous solutions. The Louisnard model was coupled with heat transport equations, and using this extended version of the model, the temperature profiles were predicted for mixtures of increasing viscosity during sonication. Using a regression formula available in literature, radical production was related to the acoustic pressure field. By including reactions and mass transport in the acoustic model, for the first time in modelling ultrasonic reactors, the full distribution of light in the reactor during sonochemiluminescence (SCL) experiments for water was quantified
Authoring training scenarios “from within” in an immersive environment with the CESTATE framework
No full textInternational audienceVirtual reality (VR) can be used to train for complex, dynamic and dangerous situations, such as disaster response. The aim of this research is to support trainers with an immersive authoring tool that facilitates the implementation of training environments, enabling both the design and execution of complex and dynamic exercises. A systematic literature review was conducted to identify VR-based authoring tools. Each environment was assessed based on variability, reusability and design assistance, with each criterion graded on a 3-point scale. Following a model-driven approach, the work presented in this article introduces the CESTATE (Cascading Effect Simulation To Authoring Training Environments) framework. It uses a metamodel to design training exercises, thus ensuring their reusability. Inheriting from the [Anonymized for peer review] paradigm, this metamodel can be used to describe all types of potentialities and cascading effects. This ensures the dynamic, and therefore, the plausibility of the virtual training environment. In addition, this framework supports the design of immersive training environments, at both design and run time. It is a generic approach. Its applicability is demonstrated in several iterations of a case study involving the training of practitioners on a complex and realistic crisis situation: a fire in a cathedral
Determination of steady-state for continuous powder mixing: Analysis of mixture properties and signal processing
No full textInternational audienceContinuous powder mixing offers many advantages over batch processes, but its industrial implementation requires control of transient phases due to startup or variations in operating conditions. Detecting the steady-state by observing the mixture properties, obtained through in-line analysis of the mixture composition, is challenging due to the significant fluctuations in these properties. However, there is no quantitative method for identifying the steady-state for continuous powder mixing. We therefore propose in this work a methodology for steady-state detection by comparing several methods of mixture property analysis and signal processing. We show that conventional methods of mixture property analysis cannot reliably and accurately detect steady-state. We conclude that the best methodology is to perform signal processing on the content of the key component in the mixture. To do this, the signal of the content of the key component is first smoothed by the Savitzky-Golay filter. Then, the standard deviation of the filtered signal is compared with a tuning parameter to detect the beginning of steady-state. This method could be used to determine the mixing conditions leading to the smallest startup time, hence avoiding costly waste
Investigation of cooling efficiency and structural characteristics of supercritical CO2 jets for machining assistance
No full textInternational audienceIn a context of safer, more cost-effective, and environmentally friendly machining processes, supercritical carbon dioxide (sCO2) emerges as a promising alternative to conventional cutting fluids. However, a consolidated understanding of the optimal sCO2 jet parameters for machining and its impact on the tool and the material remains unavailable. This work intends to address the behavior of a free and impinged sCO2 jet structure and its geometrical evolution in function of the upstream jet conditions. The supersonic structure and parameters were analyzed under varying initial pressures and temperatures in both near and far fields. The obtained images showed the detailed jet structure and highlighted the presence of three different zones within the flow: laminar, transitional then turbulent. To investigate this behavior and to better understand the jet’s cooling ability in these different zones, an in-depth analysis of the jet’s complex structure was carried out using high-speed imaging combined with an optical imaging known as Schlieren
Améliorer la recyclabilité des polymères et des composites : synthèse du projet des centres de recherche du Carnot M.I.N.E.S
No full textInternational audienceFace à l’urgence environnementale, comment repenser nos modèles industriels pour construire une économie véritablement circulaire ?À l’heure où l’exploitation intensive des ressources naturelles et l’accumulation des déchets atteignent des niveaux critiques, les cadres réglementaires européens et français fixent des objectifs ambitieux : recycler 55 % des emballages plastiques, incorporer 30 % de plastique recyclé dans les bouteilles d’ici 2030, ou encore interdire la destruction des invendus non-alimentaires. Autant de défis technologiques et organisationnels que les industriels doivent aujourd’hui relever.C’est dans ce contexte exigeant que les laboratoires du Carnot M.I.N.E.S ont conduit un programme de recherche structurant sur trois ans, mobilisant un large collectif scientifique. L’objectif était de développer des solutions concrètes pour améliorer la recyclabilité des polymères dans trois secteurs clés : bouteilles, textiles et composites. Au-delà de ce projet central, l’ouvrage présente également d’autres initiatives portées par le Carnot M.I.N.E.S, témoignant de son engagement constant pour des filières plus durables, plus responsables et plus innovantes.Destiné aux industriels, chercheurs, ingénieurs et décideurs, ce livre s’adresse également à toute personne curieuse de comprendre les enjeux techniques, environnementaux et sociétaux de la transition vers une économie circulaire. Il offre une synthèse rigoureuse et accessible des avancées scientifiques et technologiques au service du recyclage de demain : tri optimisé, intégration de matières recyclées, conception d’éco-matériaux et développement de composites recyclables. Un livre essentiel pour penser l’industrie de demain et accompagner les mutations vers un avenir plus soutenable
Contribution de l’intelligence artificielle à l’interopérabilité fédérée des organisations et son adaptation au transport en zone peu dense
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Towards a data-driven decision support system for enhanced healthcare collaboration
No full textInternational audienceCollaboration in healthcare is a complex and critical challenge, especially in environments where key resources, such as surgeons, are both scarce and costly. Operating rooms are high-stakes environments that demand precise coordination among multiple care units to ensure efficient and effective patient management. In this context, we used R-IOSUITE, a decision support system originally designed for crisis management, and now extended to model and manage collaboration across hospital units in surgical care pathways. R-IOSUITE is built upon a metamodel specifically designed to represent collaborative processes. Our research begins by adapting this metamodel to healthcare settings and the coordination of surgical patient pathways. One of the key features of the framework is its ability to infer, propose, and represent a shared, holistic planning approach across all stages of the surgical care process. The proposed framework is a POC (Proof of Concept) validated through a case study involving several hospital units. The results highlight the platform's adaptability to healthcare-specific contexts and its potential to improve both the supervision and coordination of surgical pathways. This work contributes to enabling effective collaboration in complex and resource-constrained healthcare environments.</div
On the Stability of Perfluoroisobutyronitrile in High-Voltage Circuit Breaker: A Computational Study
No full textInternational audience2,3,3,3-Tetrafluoro-2-(trifluoromethyl) propanenitrile, also known as perfluoroisobutyronitrile (CF4-CN), is the main component of the so-called g 3 gas mixture (C 3 F 7 CN-CO 2 -O 2 ), a proven alternative to SF 6 as an insulating gas in high-voltage circuit breakers. In recent years, numerous experimental investigations have been conducted to identify the principal reactions that this mixture undergoes before and during the electric arcing processes. While thanks to these efforts, several products have already been characterized in different possible experimental conditions, a full picture of CF4-CN reactivity in the high-voltage conditions of circuit breakers has yet to be reached. In this paper, we present a computational study based on density functional theory (DFT) that further expands the mapping of the possible chemical reactions of CF4-CN before (hydrolysis) and during (decomposition) electric arcing. Through a careful analysis of all possible reactions paths that includes the structural and energy characterization of reaction intermediates and products, the decomposition of C 3 F 7 CN in the presence of oxygen is evidenced, together with the formation of stable amide derivatives upon hydrolysis. This work allows the unambiguous identification of the most probable reaction paths, in terms of energy, leading to the decomposition products reported experimentally, such as CF 4 , COF 2 , or C 2 F 5 CN, as well as the reactions leading to the amide species that have been observed to form crystals in experimental conditions