Portail HAL IMT Mines Albi
Not a member yet
5440 research outputs found
Sort by
The “teapot in a city”: A paradigm shift in urban climate modeling: Review
No full textInternational audienceUrban areas are a high-stake target of climate change mitigation and adaptation measures. To understand, predict, and improve the energy performance of cities, the scientific community develops numerical models that describe how they interact with the atmosphere through heat and moisture exchanges at all scales. In this review, we present recent advances that are at the origin of last decade’s revolution in computer graphics, and recent breakthroughs in statistical physics that extend well-established path-integral formulations to nonlinear coupled models. We argue that this rare conjunction of scientific advances in mathematics, physics, computer, and engineering sciences opens promising avenues for urban climate modeling and illustrate this with coupled heat transfer simulations in complex urban geometries under complex atmospheric conditions. We highlight the potential of these approaches beyond urban climate modeling for the necessary appropriation of the issues at the heart of the energy transition by societies
Reconsidering the potential of micropyrolyzer to investigate biomass fast pyrolysis without heat transfer limitations
No full textInternational audienceCommercial analytical pyrolysis systems have become increasingly used in biomass fast pyrolysis research. Establishing experimental conditions free from heat transfer limitations using these micro-rectors has not been verified. Since accurate measurement of biomass sample temperature with these devices is not possible, the isothermal character of experiments has never been verified. In this work, numerical simulations were conducted to assess the time-temperature history of both cup and different sample arrangements and to determine the overall heat transfer coefficients at the surface of the biomass samples to confirm the pyrolysis regime based on the dimensionless analysis in the micropyrolyzer. Using both a small mass of biomass sample (≤ 50 μg) carefully arranged at the bottom of the cup and a temperature below 723 K allows the complete elimination of heat transfer limitations within the micropyrolyzer. The heating time of the biomass sample was significant (4–5 s to reach 773 K), proving that the experiment is not isothermal. Thus, evaluating the kinetics of biomass fast pyrolysis requires establishing the time-temperature history of the sample, as an essential prerequesite. Both heating profiles of biomass samples arranged in thin-film and torus were found to follow that of the cup; the time-temperature history of the sample can be determined by measuring the temperature of the cup
Design and Applications of Hydroxyapatite-Based Catalysts
No full textInternational audienceEssential reference for researchers and experts in industry highlighting the rapidly growing field of hydroxyapatite-based catalysts and their application in various chemical processes.Hydroxyapatite (Ca10(PO4)6(OH)2) is the main mineral component of human and animal bones. It is largely applied in the field of biomaterials due to its biocompatibility. Recently, hydroxyapatite-based compounds have especially gained a lot of attention by researchers in catalysis, as they are versatile and have shown precious properties of a good catalyst and catalyst support such as excellent ion-exchange capacity, high porosity, very low water solubility, controlled basicity/acidity, and good thermal stability at high temperatures.Design and Applications of Hydroxyapatite-Based Catalysts gives a detailed overview of the synthesis, characterization, and use of hydroxyapatite-based materials in catalysis. It covers synthetic hydroxyapatites (from pure chemicals or waste), natural apatites, and materials from eggshells and animal bones. The application of hydroxyapatite-based catalysts in selective oxidation, deoxygenation, selective hydrogenation, dehydrogenation reactions, organic synthesis, as well as reforming processes and production of energy carriers is reviewed. Moreover, electrocatalysis and photocatalysis using hydroxyapatite-based materials are discussed. Kinetic and mechanism studies of various chemical processes over hydroxyapatite-based catalysts are also presented. This is the first book solely dedicated to hydroxyapatite-based materials and their use in catalysis. Covers synthesis and characterization, surface and structure study, kinetic and mechanism aspects, and various applications in heterogeneous catalysis, electrocatalysis, and photocatalysis. Aimed at further stimulating research on hydroxyapatite-based catalysts, Design and Applications of Hydroxyapatite-Based Catalysts is an indispensable source-of-information for researchers in academia and industry working in catalysis
A DSS Based on a Control Tower for Supply Chain Risks Management
No full textInternational audienceThis paper presents a supply chain control tower deployed with a decision support system for supply chain risk management in a multi-source data and risk environment. The study provides a digital risk management process and a group decision making approach for companies to improve their supply chain resilience in a supply chain risk environment. We have designed the system from two perspectives. Supply Chain Control Tower and Supply Chain Risk Management. Supply chain risks are mainly all the risks faced in the process from product design to delivery to customers. Supply chain risk management is a very complex activity that requires assessing the vulnerability of all participants in the supply chain. It is a multi-step process. The Supply Chain Control Tower is a dashboard that integrates information from across the supply chain. The supply chain control tower integrates multiple data sources, key performance indicators and activity sources in the supply chain. The control tower should include an intelligent decision support system that uses decision support models and technologies, such as machine learning, to provide decision support and ranking of alternative strategies for supply chain managers. Results. In this paper, a decision support system-based supply chain control tower is designed to support supply chain decision makers in selecting the most appropriate alternative strategies to reduce the risk impact and enhance the resilience of the supply chain
Buildings energetic improvement: first elements about isolating panels layout design
No full textInternational audienceThe goal of this communication is to present the first ideas and proposition about the panels layout design problem in order to improve building energetic performances. First the origins and interest of the problem are presented. In two words, too many buildings with poor energetic performances and too low ratio of replacement lead to a very strong energetic retrofit need. Consequently, we describe the panels layout design problem, discuss some related works and propose the very first ideas in order to solve it with a heuristic approach. An example illustrates the problems and the propositions
Évaluation des risques et de la robustesse de la planification tactique des acteurs d’une chaîne logistique basée sur une plateforme cloud
No full textThe management of a multi-actor supply chain relies on a coordination pillar, which is essential to synchronize the activities of all actors and ensure a good level of end customer service rate and expected performance. Tactical planning of the supply chain is a particularly important decision-making level that aims to ensure the synchronization of physical and information flows in the supply chain. The different actors rely on planning information systems to improve their internal planning performance. They rely on rolling planning and information sharing tools to periodically revise and align their plans to adapt to uncertainties. However, over the rolling horizon, the instability due to periodic plan revisions and the effects of uncertainties are amplified along the supply chain (bullwhip effect) and increase the nervousness of the system. However, deterministic decision support systems remain limited in their ability to manage these uncertainties. Thus, the decision-maker is often exposed to a stability-reactivity dilemma in his decision making regarding the uncertainties. In the literature, different approaches are proposed for the management of uncertainties in tactical planning. However, the gap between research and industrial practices in this field remains very important in the absence of analysis of the applicability of the proposed theoretical models, whether in terms of considering the complexity of the industrial environment or the number of sources of uncertainty considered or the involvement of the decision-maker in the decision-making process. In order to overcome these limitations while considering that decision makers always exchange deterministic plans generated with existing planning tools, this thesis describes a proposal for a replanning support system for a planner at the central distribution level of a supply chain. Thus, this thesis deals with the following three aspects : 1/ Integrate the knowledge of an expert on the variability of the cumulative plans of other actors. 2/ Integrate this knowledge for uncertainty modeling and risk assessment and robustness of a decision maker's deterministic plans. 3/ Study the applicability of the proposed approach in a real dynamic industrial environment by considering the independence of the decision maker in the decision making. A methodological contribution of this thesis lies in the adaptation of a risk management methodology from their identification and modeling of uncertainties to the evaluation of their criticality and the mitigation of their impact. A theoretical contribution is based on the proposal of a quantitative approach, based on fuzzy sets and possibility theory, for the evaluation of the robustness of a decision-maker's plans, regarding the risks linked to the respect of the constraints induced by the decisions of his upstream supplier (supplies) and his downstream customers (demand). A practical contribution concerns the implementation of an interactive cloud platform for decision support integrating the main functionalities of the decision support system based on the proposed approach: dynamic database, interactive interfaces, different levels of evaluation aggregation, collaboration and configuration. Finally, a 'Serious Game' is elaborated from the analysis of the processes of an industrial case PFDC (Pierre Fabre Dermo-Cosmetics) and used as proof of concept in a dynamic context.La gestion d'une chaîne logistique multi-acteurs repose sur un pilier de coordination, essentiel pour synchroniser les activités de tous les acteurs et assurer un bon niveau de taux de service du client final et des performances attendues. La planification tactique de la chaîne logistique est un niveau de décision particulièrement important qui vise à assurer la synchronisation des flux physiques et d'informations dans la chaîne. Les différents acteurs s'appuient sur des systèmes d'information de planification pour améliorer leurs performances de planification interne. Ils s’appuient sur la planification à horizon glissant et les outils de partage d'informations pour réviser et aligner périodiquement leurs plans afin de s'adapter face aux incertitudes. Cependant, sur l'horizon glissant, l'instabilité due aux révisions périodiques des plans et les effets des incertitudes sont amplifiés le long de la chaîne (effet bullwhip) et accroissent la nervosité du système. Les systèmes d'aide à la décision déterministes restent toutefois restreints pour la gestion de ces incertitudes. Ainsi, le décideur est souvent confronté à un dilemme stabilité-réactivité dans sa prise de décision face aux incertitudes. Dans la littérature, différentes approches sont proposées pour la gestion des incertitudes dans la planification tactique. Cependant, l'écart entre la recherche et la pratique industrielle dans ce domaine reste très important en absence d'analyse de l'applicabilité des modèles théoriques proposés, que ce soit au niveau de la prise en compte de la complexité de l'environnement industriel ou du nombre de sources d'incertitude considérées ou encore de l'implication du décideur dans le processus de prise de décision. En vue de surmonter ces limitations et tout en considérant que les décideurs échangent toujours des plans déterministes générés avec les outils de planification existants, cette thèse décrit une proposition de système d'aide à la replanification pour un planificateur au niveau de la distribution centrale d'une chaine logistique. Ainsi, cette thèse traite des trois aspects suivants : 1/ Intégrer la connaissance d'un expert sur la variabilité des plans cumulés des autres acteurs. 2/ Intégrer cette connaissance pour la modélisation de l'incertitude et l'évaluation des risques et de la robustesse des plans déterministes d'un décideur. 3/ Étudier l'applicabilité de l’approche proposée dans un environnement industriel dynamique réel en considérant l'indépendance du décideur dans la prise de décision. Un apport méthodologique de cette thèse réside dans l'adaptation d'une méthodologie de gestion des risques depuis leur identification et la modélisation des incertitudes jusqu'à l'évaluation de leur criticité et la mitigation de leur impact. Un apport théorique repose sur la proposition d'une approche quantitative, basée sur les ensembles flous et la théorie des possibilités, pour l'évaluation de la robustesse des plans d'un décideur, au regard des risques liés au respect des contraintes induites par les décisions de son fournisseur en amont (approvisionnements) et de ses clients en aval (demande). Un apport pratique concerne la mise en œuvre d'une plateforme cloud interactive d'aide à la décision intégrant les principales fonctionnalités du système d'aide à la décision basé sur l'approche proposée : base de données dynamique, interfaces interactives, différents niveaux d'agrégation des évaluations, collaboration et configuration. Enfin, un 'Serious Game' est élaboré à partir de l'analyse des processus d’un cas industriel PFDC (Pierre Fabre Dermo-Cosmétique) et utilisé comme preuve de concept dans un contexte dynamique
Intranasal immunization with chitosan microparticles enhances lack-dna vaccine protection and induces specific long-lasting immunity against visceral leishmaniasis
No full textInternational audienceDevelopment of a protective vaccine against Leishmania depends on antigen formulation and adjuvants that induce specific immunity and long-lasting immune responses. We previously demonstrated that BALB/c mice intranasally vaccinated with a plasmid DNA encoding the p36/LACK leishmanial antigen (LACK-DNA) develop a protective immunity for up to 3 months after vaccination, which was linked with the systemic expression of vaccine mRNA in peripheral organs. In this study, LACK-DNA vaccine was associated with biocompatible chitosan microparticles cross-linked with glyceraldehyde (CMC) to boost the long-lasting immunity against the late L. infantum challenge. Infection at 7 days, 3 or 6 months after vaccination resulted in significantly lower parasite loads when compared with non-vaccinated controls. Besides, LACK-DNA-chitosan vaccinated mice showed long-time protection observed after the late time point challenge. The achieved protection was correlated with an enhanced spleen cell responsiveness to parasite antigens, marked by increased proliferation and IFN-γ as well as decreased IL-10 production. Moreover, we found diminished systemic levels of TNF-α that was compatible with the better health condition observed in LACK-DNA/CMC vaccinated-infected mice. Together, our data indicate the feasibility of chitosan microparticles as a delivery system tool to extend the protective immunity conferred by LACK-DNA vaccine, which may be explored in vaccine formulations against Leishmania parasite infections
Impact of annealing treatment on the fatigue behavior of Inconel 625 produced by laser‐based powder bed fusion
No full textInternational audienceLaser-based powder bed fusion (LPBF) is attractive to build complex parts in spite of the low machinability of Inconel 625. The LPBF microstructures and tensile properties are well documented in literature. But fatigue properties and impact of the LPBF intrinsic defects and microstructures on the crack initiation and propagation mechanisms are uncommon. Low and high-cycle fatigue tests at room and service temperature presented in this paper prove that the LPBF defects shorten the crack initiation stage. After annealing heat treatment, the microstructure adapts to the defects, and the fatigue response becomes similar to a free defect material. The fatigue life of as-built Inconel 625 is lower than 50% of its monotonic yield tensile strength (YTS) while the annealed material reaches 100% of its YTS. The propagation rate is slowed by the homogeneous annealed microstructure and improved ductility resulting from removal of dislocation cells and changes in grain morphology
A decision support system for strategic supply chain capacity planning under uncertainty: conceptual framework and experiment
No full textInternational audienceSupply chains now cope with a lot of uncertainties, and their stakeholders are intensely interconnected, revealing new opportunities at a tremendous pace. In this context, companies must rethink their decision support systems to remain competitive. Particularly strategic supply chain capacity planning systems that should ensure resource availability. Unfortunately, existing systems do not satisfactorily consider this new deal. Therefore, this paper develops a conceptual framework providing guidelines for designing a decision support system for strategic supply chain capacity planning under uncertainty. To validate the conceptual framework, a decision support system has been designed accordingly, and two industrial experiments have been conducted
