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Excipients lipidiques et technologie d'enrobage à chaud : impact opérationnel et fonctionnel
No full textHot-melt coating by fluidised bed consists of delivering molten lipids onto surface of substrate particles in suspension and let them solidify with air-cooling. The process is evidently solventless and therefore time-, cost-efficient and eco-friendly. Lipids constitute a generally-regarded-as-safe class of excipients. Despite those advantages, challenges reside in the fact that their physicochemical and biopharmaceutical properties have not been thoroughly investigated. This thesis dealt with these challenges by considering manufacturability, product stability and release properties. In the first phase “formulation development”, a simple and nimble experimental approach was developed for process and product characterisation in early stage. NaCl, as active substance, allows for fast-track research conduct. With their diverse properties (e.g. complex-mixture vs. pure substance, polymorphism and crystallisation, adaptability to different processing approaches), beeswax, tristearin and trilaurin were chosen as coating materials under research. Additive addition was indispensable and additives of different types were tested with those three lipid systems: (I) polysorbates, (II) sorbitans, (III) vitamin E TPGS and (IV) talc. Besides, several physical and in vitro characterisation techniques have been established, for instance, for rapid screening of solid lipid-additive combinations, in situ monitoring of polymorphic transformation and crystal growth, coupling of digestion and release testing in biologically simulated media. In the second phase “pharmaceutical applications”, three beeswax-, tristearin- and trilaurin-based formulations were selected for coating amorphous solid dispersions of praziquantel. The objectives are (i) to study bioaccessibility of the amorphous active substance coated with lipids of varying digestibility and (ii) to investigate long-term stability of these hot-melt coated products. In conclusion, selection of good additives is important for development of solid lipid-based formulated products. In effect, they can improve productivity of coating operations as well as product performance (stability, release profile).L'enrobage à l'état fondu en lit fluidisé consiste à déposer du lipide fondu sur la surface des particules de substrat en mouvement et à le laisser refroidir à l'aide de l'air de fluidisation. La mise en forme n'a pas évidemment recours aux solvants. Ainsi, cette technologie fait économiser du temps et des ressources financières et est dite écologique. Les lipides constituent une catégorie d'excipients « généralement reconnus inoffensifs ». Malgré ces avantages, les challenges résident dans le fait que leurs propriétés physico-chimiques et biopharmaceutiques n'ont pas été explorées à fond. Cette thèse traite de ces défis en considérant la manufacturabilité, la stabilité et les propriétés de relargage du produit. Dans la première phase “développement de formulations”, une approche expérimentale facile et agile a été conçue pour la caractérisation de procédé et produits dans un premier temps. L'utilisation de NaCl, comme noyau actif, permet un conduit de recherche très fluide. Dotées des propriétés diverses (e.g. mélange complexe vs. substance pure, polymorphisme et cristallisation, adaptabilité aux approches de mise en forme différentes), la cire d'abeilles, la tristéarine et la trilaurine ont été sélectionnées comme matières enrobantes à l'étude. L'addition d'additif(s) a été indispensable et les additifs de nature différente ont été testés sur ces trois systèmes lipidiques : (I) polysorbates, (II) sorbitanes, (III) vitamine E TPGS et (IV) talc. D'ailleurs, plusieurs techniques de caractérisation physiques et in vitro ont été mises en place, pour l'instant, en vue de cribler rapidement des combinations lipide-additif, d'observer in situ la transformation polymorphique et la croissance cristalline, de coupler des tests de digestion et relargage dans le milieu biologiquement simulé. Dans la seconde phase “applications pharmaceutiques”, trois formulations contenant de la cire d'abeilles, de la tristéarine et de la trilaurine ont été choisies afin d'enrober les dispersions solides amorphes du praziquantel. Les objectifs sont (i) d'étudier la bioaccessibilité de ce principe actif amorphe enrobé des lipides dont la digestibilité est différente et (ii) d'investiguer la stabilité à long-terme des produits ainsi enrobés. En conclusion, le choix de bons additifs s'avère important pour le développement des produits formulés à base de lipides solides. En effet, ils peuvent aider à améliorer la productivité d'opérations d'enrobage ainsi que la performance du produit (stabilité, propriétés de relargage)
Modelling the Refuelling of Hydrogen Fuel-Cell Heavy-Duty Vehicles with Multiple Heterogenous Tanks
No full textInternational audienceRoad transport greenhouse gases (GHG) emissions accounts for over one fifth of global CO2 emissions in the EU. In Europe in recent years, road transport is the only sector whose emissions have unfortunately not stopped rising. This is particularly true for the heavy-duty mobility, such as trucks, city buses and long-distance buses, which account for over 25% of GHG emissions [1]. One of the most promising technologies to decarbonize heavy-duty transport (trucks, buses, trains, boats) is hydrogen fuel cell technology [2]. The development of this technology requires, besides the development of the vehicles, a parallel effort in the advance of hydrogen refuelling infrastructure and the related refuelling protocols.In terms of vehicle development, the effort required to maintain a range similar to that of fossil-fuelled heavy-duty vehicles is significant. For this purpose, the fuel cell heavy-duty vehicles (FC-HDVs) need bigger onboard storage systems than fuel cell light-duty vehicles (FC-LDVs). To achieve the required hydrogen storage volume, automotive original equipment manufacturers (OEMs) have to exploit any available space in the vehicle by inserting multiple hydrogen storage tanks, often of different sizes, which is not the case for FC-LDVs.This configuration of the on-board hydrogen storage system could have a significant impact on the derivation of parameters for advanced protocols (such as those defined in the European PRHYDE project [3]), as well as on the evaluation of the vehicle's instantaneous state of charge (SOC). Indeed, due to the different tank sizes of the FC-HDV storage system, the mass flow rate distribution between the tanks, the pressure evolution in each tank size and the temperature rise in the different tanks cannot easily be predicted. Thus, the models used to derive the parameters of FC-HDV refuelling protocols should therefore be updated to consider these effects. Moreover, fine modelling of the evolution of these parameters during refuelling would enable us to accurately estimate the thermodynamic state of each tank in the vehicle hydrogen storage system at the end of each refuelling session. Knowing this thermodynamic state will enable the automotive OEMs to know where to place the sensors needed to assess the vehicle's SOC.The aim of this work is therefore to propose a thermodynamic model to simulate the refuelling of a hydrogen storage system for HDVs with multiple heterogeneous tanks
Influence of the Coating Brittleness on the Thermomechanical Fatigue Behavior of a β-NiAl Coated R125 Ni-Based Superalloy
No full textInternational audienceThe brittleness of an aluminide diffusion coating protecting a René 125 Ni-based polycrystalline superalloy was investigated over a wide range of temperatures in its as-received and thermally aged form. Isothermal and thermal cycled aging were performed on the coated system at a maximum temperature of 1100 . Microstructure evolutions and damage initiation within the coating were characterized. Interrupted tensile tests and thermomechanical fatigue tests were conducted to document critical stress-strain conditions leading to the coating cracking and lifetime for the case of thermomechanical fatigue loading. Advanced digital image correlation and acoustic emission techniques were used to detect coating cracking. Isothermal oxidation or cyclic oxidation led to improved strain-to-failure due to metallurgical evolutions and also longer fatigue life under thermomechanical fatigue conditions
Assessing and Enhancing Readiness in Hyperconnected Supply Chains
No full textInternational audienceThis paper investigates the resilience of supply chains (SCs) against a backdrop ofescalating disruptions, developing a quantitative, performance-oriented metric to evaluate SCreadiness and the efficacy of Physical Internet (PI) concepts in enhancing SC resilience. Weemploy the resilience triangle concept, traditionally used in infrastructure resilienceassessments, to measure SC performance dynamics over time. Our findings reveal that PIconcepts significantly improve SC resilience by improving the distribution and storage of goodsacross a network of Open Contracted Storage Centers (OCSCs). Sensitivity analysis furtherdemonstrates the profitability of these strategies, even when the holding cost ratio in OCSCs issubstantially higher than in traditional warehouses. This research contributes to the field byproviding a framework for a priori SC resilience assessment, offering insights into the potentialof PI concepts to create more adaptive, robust, and efficient SCs. Future research directionsinclude applying these findings to various industrial sectors and exploring long-term impactson global SC networks
Assessing texturometer-derived rheological data for predicting the printability of gummy formulations in SSE 3D printing
No full textInternational audienceSemi-solid extrusion (SSE), an additive manufacturing technique, is gaining significant attention for the printing of thermosensitive drugs. Hydrogels, one of the materials used in SSE, have emerged as a focus in pharmaceutical applications due to their ability to control the release of therapeutic agents spatially and temporally. Understanding the non-Newtonian flow and evaluating the mechanical properties of hydrogel-based materials during extrusion is, however, essential for successful 3D printing. Thus, users often find themselves conducting both rheological and texture profile analyses to characterize the hydrogel. While texturometers are primarily used to evaluate mechanical or sensory properties, viscosity measurements are typically performed using rotational rheometers or viscometers. In this study, we demonstrated how comparable rheological information can be obtained using a texturometer as a capillary rheometer. By preparing similar formulations to a previous study, we compared the rheological data obtained from a rotational rheometer to the data obtained from the texturometer. The means of the parameters obtained by fitting the data from both techniques to the power law model showed insignificant differences. In addition, three clusters were formed based on the flow behaviour and printability of the samples using principal component analysis. Furthermore, the printability was predicted using the samples’ consistency and flow indexes, and the regression coefficient was 96.62 and 60.03 % for capillary and rotational flow parameters, respectively. This approach thus holds the potential to streamline the time, expertise and equipment required for the rheological characterization of hydrogels for applications in semi-solid extrusion
A force-inspired paradigm for performance-based decision support—Physics of Decision application in nonlinear dynamical systems
No full textInternational audienceThis paper provides a perspective on performance-based decision support. The chosen approach is based on the principles of “Physics of Decision”, which considers the performance of a system as a physical trajectory within the boundaries of its performance indicators that might be deviated through variation of system parameters. According to the overall premise of employing the state-space method to simulate physical systems, this work presents a decision aggregation method in dynamic systems. The core contribution is to propose a multi-criteria performance framework to manage multi-input-multi-output (MIMO) system performance with a combination of affordable decisions. A nonlinear inventory-workforce management model has been used to demonstrate the proposed approach
Modélisation du productible énergétique annuel de centrale solairehybride PV-CSP
No full textNational audienceLes centrales hybrides PV-CSP se définissent par la coopération de sous-systèmes photovoltaïques (PV) et thermodynamiques (CSP) pour convertir une même source d’énergie, afin d’améliorer l’efficacité de conversion et d’accroître la pilotabilité de la production électrique.Dans l’objectif d’évaluer la valeur ajoutée en terme de productible énergétique, nous étudions une centrale hybride PV-CSP utilisant un collecteur cylindro-parabolique ainsi que les sous- systèmes fonctionnant de manière autonome, notamment un système PV à suivi un axe, un système PV à concentration et un système CSP.Les centrales étudiées dépendent de plusieurs paramètres opératoires que sont la concentration géométrique, la température de fonctionnement et le niveau d’énergie de la bande interdite des cellules PV ainsi que la température cible du fluide caloporteur du système CSP. L’objectif de l’étude est de construire un modèle physique permettant de déterminer le productible énergétique annuel de ces centrales, puis d’identifier les conditions opératoires telles que les performances des centrales hybrides surpassent celles des centrales autonomes.En utilisant les données météorologiques d’Odeillo (dans les Pyrénées Orientales) et d’Atacama (région désertique du Chili), deux sites aux ressources solaires très différentes sont considérés. En particulier, la géométrie retenue est celle du collecteur Eurotrough, sur laquelle nous étudions la possibilité de positionner des cellules PV sur le réflecteur (architecture nommée PV Mirror) ou sur le récepteur (architecture nommée PV Topping). À partir des données météorologiques et de la position du soleil, nous déterminons les irradiances des rayonnements directs et diffus et leurs distributions spectrales, ainsi que les différentes pertes dues à la géométrie du collecteur. Ces calculs du rayonnement sont ensuite couplé à un modèle empirique de la thermique de l’absorbeur du CSP et au modèle de bilan détaillé en limite radiative des cellules PV.Dans ce contexte, une large gamme de valeurs des paramètres principaux définis précédemment a été identifié comme permettant une production énergétique supérieure à celle d’une centrale autonome similaire. Par rapport à une installation CSP, l’architecture PV Mirror amène à une augmentation du productible de 21% à Odeillo mais de seulement 9% à Atacama. Pour les deux emplacements étudiés, le PV Topping est l’architecture la plus performante avec une augmentation du productible relative à celle du CSP autonome de 29% et 26% aux emplacements d’Odeillo et d’Atacama respectivement.De futurs travaux auront notamment pour objectif d’adopter une autre approche temporelle afin d’éviter des effets de transition jour-nuit. De même, la prise en compte de la dépendance spectrale des propriétés radiatives des différents éléments optiques, et donc dans la thermique de l’absorbeur, est un objectif majeur pour l’amélioration de cette modélisation
Knowledge on demand: the future of decision support systems?
No full textInternational audienceThe availability and quality of the information system supporting crisis management depends on the existence of up-to-date, comprehensive and reliable knowledge bases, despite the multidisciplinary nature of the information to be exchanged, the actions, and the decisions to be taken. This article proposes a method to benefit from pre-trained language models to automatically update these knowledge bases at both design time and run time. We offer a model-based extraction process and a dedicated automated validation process. These two contributions are illustrated and discussed around a case study: an emergency decision support system used to prepare for and respond to an unexpected mass gathering at an abandoned French aerial base
Maturity, characterisation and decision support system: a multidisciplinary approach to select WAAM-CMT process parameters
No full textInternational audienceThe use of metal additive manufacturing (MAM) processes is still mainly confined to academic R&D platforms despite numerous proofs of manufacturability. Even today, too few manufacturers are taking the plunge and equipping themselves internally with these new technologies. The reasons could be economic, skills-related or simply a lack of knowledge about these technologies. In this work, a methodological framework in three steps is proposed to promote appropriation of MAM processes for and by industrials. This framework has been designed from the point of view of a manufacturer who needs to produce dedicated types of parts and who seeks to select (i) the relevant MAM process and (ii) the process parameters required to reach targeted mechanical and industrial performance. This study is limited to directed energy deposition (DED) processes. First, a model to assess the maturity of DED processes was developed, based on well-known existing models such as technology readiness levels and manufacturing readiness levels. Considering their limitations, a new and innovative model was proposed for DED processes, taking into account the technology-use case couple (TUCC). It has been applied to the maturity assessment of three DED technologies coupled with three use cases (new part manufacturing, part repair and added functions to parts) and three materials (stainless steel, titanium and aluminium). Once maturity has been assessed, this study focused on the manufacturing of new parts with wire arc additive manufacturing (WAAM). The geometry of the AM parts and the material used (316L) are based on an industrial case study. Nine parts were manufactured varying first-order process parameters (wire feed speed and torch speed). Energy consumption, manufacturing time and quantity of raw material used have been measured in-situ. Then, destructive tests were performed providing the mechanical behaviour of 316L WAAM parts. In-situ and post-process collected data enhanced the process knowledge. Based on that, a decision support system was finally developed (i) to find Pareto optimal solutions with a genetic algorithm and (ii) to choose between these alternatives using TAMARIN, a multi-criterion ranking algorithm linked to a dynamic user interface. The proposed methodological framework has been applied to one AM process, for one use case, within specific process parameter ranges. Further investigations to transfer it to other use cases, other AM processes and other parameters are therefore wide open
Strain localization in the Alloy 718 Ni-based superalloy: From room temperature to 650 °C
No full textInternational audienceIrreversible deformation in relation to the microstructure was investigated for a polycrystalline Ni-based superalloy (Alloy 718) from room temperature to 650 °C using high-resolution digital image correlation (HR-DIC) techniques. Interrupted tensile tests were performed under a protective atmosphere to ensure the stability of the speckle pattern to track kinematics fields from surface analyses. In-plane strain localization was captured using HR-DIC on scanning electron microscopy (SEM) images. A statistical analysis of different strain localization events in relation to the microstructural features was conducted, i.e., intragranular slip localization, slip localization parallel to and near Σ3-twin boundaries (Σ3-TB), and grain boundary sliding (GBS). Alloy 718 exhibited slip localization at room temperature and 350 °C. Intense strain localization develops parallel and in the vicinity of Σ3-TB from the onset of the microplasticity. Few intense slip stimulated-grain boundary sliding events were found due to slip localization on both grains adjacent to the grain boundary. At 650 °C, Alloy 718 experienced grain boundary sliding at the onset of the yield without particular slip localization in adjacent grains. At lower temperatures, strain localization parallel to and near Σ3-TB was intense, and intragranular slip localization intensified with increasing macroscopic deformation. Particular microstructural configurations were found at 650 °C leading to premature damage: (i) sub-surface cavitation at grain boundaries, and (ii) grain boundary cracking due to intense shearing near a Σ3-TB