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Ingénierie dirigée par les modèles pour un pilotage robuste des processus de soins à l’hôpital
No full textNational audienceLes établissements de santé érigent la sécurité et la qualité des soins en enjeu stratégique. Cependant, atteindre ces buts passe par une faculté à réagir face aux risques sans perdre la maîtrise dans le pilotage du système pour maintenir la performance escomptée. Dans ce contexte, le secteur de la santé est toujours en quête de progrès sur ces thèmes. La mise en oeuvre d’une gestion des risques et des processus métier adaptée aux besoins des établissements hospitaliers est la motivation de l’étude décrite dans cet article. Nous avons exploré de telles pistes et, contribuant à ce domaine, le présent document explique la plus-value d’une méthode de gestion intégrée des risques et des processus métier de soins. Un cadre théorique vise d’abord à améliorer la maturité des organisations de santé en matière d ‘événements indésirables. Une étude sur un cas d’école illustre comment un outil adapté permet de passer à la pratique et de travailler au sein de ce cadre
Toward an Educational Supply Chain Operations Reference Model
No full textInternational audienceEducational success is a global issue for human societies in our Volatile, Uncertain, Complex and Ambiguous (VUCA) world. Access to quality education is the fourth sustainable development goal set by United Nations member countries. Unfortunately, educational systems have generally a performance deficit. To change this situation, we assume in this paper that they could benefit from some technical contributions developed initially for commercial supply chains to optimize the production flow of goods and services. To this end, we study the transposition of the well-known Supply Chain Operations Reference model (SCOR) to educational systems which manage flows of learners. Indeed, the path that a learner follows is a succession of business processes from one educational organization to another that constitute an educational chain that could be improved through the Educational Supply Chain Operations Reference (EducSCOR) model we developed in this paper. It proposes a hierarchical structure of the educational business processes and a set of associated performance indicators allowing quick and effective assessment of educational systems and their networks. A first application case to a big French educational system dedicated to apprenticeship training is proposed to highlight the potentialities of the proposal
Génie de la Réaction Chimique : les réacteurs homogènes
No full textMasterLe Génie de la Réaction Chimique (GRC) est une branche du génie des procédés qui traite des méthodes de mise en œuvre rationnelle des transformations de la matière et des appareils dans lesquels sont conduites les réactions : les réacteurs. » Le plan de ce cours est le suivant : Un chapitre préliminaire fournit quelques rappels utiles de mathématiques et méthodes numériques.Le premier chapitre fait le point sur les notions de base du Génie de la Réaction Chimique, avec la classification des réactions et des réacteurs, quelques éléments de technologie, les définitions des grandeurs caractérisant une réaction chimique (coefficients stœchiométriques, taux de conversion et avancement) et le rappel des éléments de base de thermodynamique et de cinétique chimique (vitesse de réaction, lois usuelles, liens avec la thermodynamique).Le deuxième chapitre est consacré aux réacteurs idéaux isothermes. Les bilans de matière seront explicités dans plusieurs cas classiques : réacteur agité discontinu, réacteurs continus parfaitement agité ou à écoulement piston ; avant de détailler le comportement de ces réacteurs idéaux lorsqu'ils sont le siège d'une seule ou de plusieurs réactions, et d'aborder le problème de l'optimisation de la conversion ou du rendement.Le troisième chapitre traite de l'étude de l'écoulement dans les réacteurs réels grâce aux mesures de Distribution des Temps de Séjour (DTS) : après la description de la méthode et de la fonction de distribution associée, le diagnostic des écoulements et leur modélisation seront étudiés.Le quatrième et dernier chapitre s'intéresse aux effets thermiques dans les réacteurs : l'écriture des bilans d'énergie sera détaillée, puis la Progression Optimale de Température (POT) et le problème de l'emballement thermique seront abordés
Foaming of PLA Cellulose Composites : Effect of Fibres on the Solidification and Crystallisation Behaviour
No full textInternational audienceIn many industrial fields, the development of porous and light polymer composite structures is of great interest because of their several advantages compared to a massive solid of the same chemical nature. Batch foaming of polymers is a discontinuous process carried out normally in an autoclave. The samples are saturated in a pressurised vessel, and their foaming is achieved by inducing an instability into the system, which can be sudden drop in pressure or by a raise in temperature. Polylactic acid (PLA) is a well-known and commercially available biopolymer that can be produced from different sources. Its different characteristics generated a great deal of interest in various industrial fields as in the foaming one. PLA’s crystallisation kinetics is reported to be slow and can be enhanced by using different solid additives (filler) as crystal-nucleating agents [1-2]. It is known that crystallisation kinetics of polymers can influence different polymer shaping processes such as injection, moulding, foaming, etc and, that additives can modify the crystallisation kinetics of the polymers; but it is not reported in literature whether the shape and dimension of the additives matter and, consequently there is not information about their effect on processes like foaming.This works aims to understand the effect of the filler content and aspect ratio (length/diameter) on PLA’s solidification and crystallisation kinetics. Cellulose fibres (Rettenmaier France) of different aspect ratios (1 and 6) were compounded with PLA by extrusion at 5, 20 and 30 %wt, then injected into discs. Solidification and crystallization kinetics of the materials were evaluated through polarized optical microscopy with hot-stage (POM), isothermal DSC and oscillatory shear rheology (at an angular frequency of 1 rad/s). In all tests, pure PLA and composite samples were heated up to melting and then cooled to the desired isothermal crystallization temperature, ranging from 80 to 120 °C.In general, crystallisation induction (time to observe the first crystals) and half crystallisation times were reduced with increasing fibre content but also when increasing their aspect ratio. Crystallisation rate constant, increased with both, content and aspect ratio. Studying the evolution of the viscosity of the samples with time at a certain temperature, in general it was shown that after a first plateau corresponding to the beginning of the isotherm, a rise in viscosity attributed to the solidification of the polymer occurred. A second rise in viscosity corresponding to the crystallisation of the sample was observed depending on crystallisation conditions. This work shows that fibre content and aspect ratio are two important parameters in the solidifcation and crystallisation behaviour of PLA-cellulose composites. This result emphasizes that we can choose between two different additives or even master the crystallisation kinetics of PLA not only by chemical interactions between additives and PLA, but by just changing the aspect ratio of filler. This opens interesting perspectives for the development of bio-based materials and allows us to go one step further in the understanding of composites shaping processes dependent on crystallisation like foaming. An interesting question lies now on the table: can we master the foaming of PLA composites by changing the aspect ratio of the fillers to obtain materials with suitable functional properties
Effects of cellulose-lignin interaction on the evolution of biomass pyrolysis bio-oil heavy components
No full textInternational audienceCellulose, lignin and their mixture were pyrolyzed at 500–700 °C for 60 s and 90 s to investigate the influence of cellulose-lignin interaction on the evolution of biomass pyrolysis bio-oil heavy components with temperature and reaction time. Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the composition and main functional groups of the heavy oil. Strong interaction among cellulose and lignin was revealed, which promoted the generation of lipids and unsaturated hydrocarbons while inhibiting the generation of the condensed aromatic hydrocarbons, phenolic species and sugars in the heavy components. With the use of van Krevelen diagrams, three reaction pathways are proposed to explain the evolution of heavy species under the influence of interaction, which is strongly affected by the removal of oxygen containing functional groups
Determination of a degradation-induced limit for the consolidation of CF/PEEK composites using a thermo-kinetic viscosity model
No full textInternational audienceIn order to assess the impact of the thermal degradation of PEEK on the consolidation ofcomposite preforms, an impregnation model taking into account degradation is proposed.It includes a viscosity model based on a double Arrhenius law describing the viscosityincrease due to degradation. The implementation of this viscosity model into an impreg-nation model allowed to define an intrinsic processing window for the manufacturing ofCF/PEEK composites based on a criterion of irrecoverable viscosity level. The simulationshows a good correlation with the experimentally measured porosity rates of commingledpreforms. It predicts the absence of impregnation when increasing the consolidation timeor the processing temperature from 380 to 410°C. Above 410°C or when increasing thepressure, however, a discrepancy is observed between the model and the simulation. Thisdiscrepancy is attributed to a change in the degradation kinetics resulting from a changein oxygen access
Experimental and numerical study of combining encapsulated phase change material to sensible heat storage material in one-tank pilot scale thermal energy storage
No full textInternational audienceThis work presents the design, experimental and numerical results related to a pilot-scale one-tank (thermocline) thermal energy storage (TES) combining latent and sensible heat storage materials with synthetic oil as heat transfer fluid (HTF). The layer of phase change material (PCM) is used to enhance the thermal performance of the TES. Alumina spheres are used as sensible heat storage materials, while the PCM is NaNO3 (sodium nitrate). The PCM is encapsulated inside 140 stainless steel tubes. The volume of the PCM represents 5.5% of the storage volume. NaNO3 was found safe to use with the synthetic oil at the designated operating conditions in case of leaks in the tank. The influence of the phase change material on HTF temperatures were observed experimentally during charge, discharge and stand-by. A numerical model that couples two one-dimensional (1D) physical methods is developed. It simulates natural convection within the PCM capsules by modifying the thermal conductivity of the material. The enthalpy porosity method is applied to simulate the phase changing behavior and a single equation estimates the liquid fraction of the PCM at each time step. The model is validated from the experimental results. This validation reveals that there is still a high fraction of unsolidified PCM in the tubes during discharge, which indicates that the performance of the combined TES solution is limited by heat transfer within the encapsulation tubes
Preparation of Supported Metal Single-Atom Catalysts on Metal Oxides and Hydroxides
No full textInternational audienceDuring the last decade, great attention has been devoted to supported metal single-atom catalysts (SACs), due to the maximal metal utilization and the unique reactivity of such materials. The preparation of high-loading, stable isolated metal atoms with the desired local environments remains the main challenge for the industrial application of SACs. In this chapter, we discuss in detail the most representative methods for the preparation of SACs on oxide and hydroxide supports to give to the reader a complete idea of the different steps of each procedure employed and the final stability of the deposited single atoms. Moreover, we focus our attention on the “bottom-up” methods, which represent a facile and universal route for the direct preparation of SACs on metal oxides and hydroxides
Introduction to Supported Metal Single Atom Catalysis
No full textInternational audienceThe main purpose of this introductory chapter is to: (i) familiarize non-experts in the field with this type of catalysis, and (ii) draw the attention of experts to related and complementary fields of which a basic knowledge may be necessary for a good understanding of this type of catalysis. More specifically, we intend to: (i) introduce the key aspects of catalysis with supported metal single-atom catalysts, (ii) discuss the drawing together of closely aligned topics, and (iii) acknowledge the challenges and possible opportunities around the area
Hydrogen production from biogas: Process optimization using ASPEN Plus®
No full textInternational audienceThis work is part of the VABHYOGAZ (valorization of biogas into hydrogen) program, which targeted the industrial deployment of hydrogen production from biogas in France. To-date, different processes of methane reforming, such as steam reforming of methane (SRM), dry reforming of methane (DRM) and tri-reforming of methane (TRM), have been studied in the literature, but only SRM is applied at industrial scale. Since SRM is an energy-intensive process, a critical analysis of these routes for hydrogen production from biogas is indispensable for process optimization. This has been addressed in this work, by using ASPEN Plus® simulation. Different global processes of hydrogen production from biogas, via DRM, SRM, or TRM, with or without tail gas recycling, have been studied. Among them, hydrogen production using TRM technique (H2-TRM0.3C process) with a partial recycling of tail gas (30%) was found to be the best option, leading to the highest hydrogen production rate and the best energy yield. H2-TRM0.3C process was also found to be more efficient than the actual industrial process (H2-REF), which is based on SRM technique. Under the same conditions, H2-TRM0.3C process led to a higher H2 production (8.7% more), a lower total energy consumption (18.6% less), and a lower waste heat generation (15.4% less), in comparison with the actual industrial process (H2-REF)