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Isru taskforce in Toulouse toward in situ autonomous electrochemical and additive manufacturing processes of lunar
No full textInternational audienc
Using Virtual Reality to Facilitate Common Operational Pictures ́Representation
No full textInternational audienceDuring crisis, different organizations are involved, each with their jargon and communication devices. Information about the situation is needed by all and it is vital to be able to share the data. To centralize that data, Common Operational Pictures are implemented, but they do not remove the risk of information overload. We propose to use virtual reality to create a virtual environment improving COP representations, thus improving situational awareness and collaborative decision making
Titanium Alloy Milling Using Abrasive Water Jet for Repair Application: Modifications in Surface Quality and Material Integrity Following Plain Water Jet Cleaning
No full textInternational audienceAbrasive Water Jet (AWJ) machining has proven to be an effective and versatile technique for milling various kinds of materials, even with low machinability such as aerospace grade titanium alloy Ti6Al4V. Many studies have been performed in order to master this technology and produce geometrically accurate shapes. However, in the context of bonding repairs which require surfaces free from foreign bodies, AWJ machining presents a significant drawback in form of abrasive grit embedment. The goal of this present work is then to investigate the effect of a post-AWJ machining cleaning operation using Plain Water Jet process (PWJ – i.e. without abrasive particles) on the surface quality and material properties. For this, several characterization techniques were employed. It was concluded that the contamination has been reduced by 65% without noticeable changes in depth of cut and crater volume. The AWJ milling operation produced surface and subsurface hardening as well as biaxial compressive residual stress, mostly piloted by the jet pressure. PWJ cleaning reduced the depth of hardening without clear modification in surface hardness
Three viewpoints on null-collision Monte Carlo algorithms
No full textInternational audienceIn 2013, Galtier et al. [1] theoretically revisited a numerical trick that had been used since the very beginning of linear-transport Monte-Carlo simulation: introducing “null” scatterers into a heterogeneous field to make it virtually homogeneous.The rigorous connection between null-collision algorithms and integral formulations of the radiative transfer equation led to null-collision algorithms being used in distinct contexts, from atmospheric or combustion sciences to computer graphics, addressing questions that may strongly depart from the initial objective of handling heterogeneous fields (handling large spectroscopic databases, non-linearly coupling radiation with other physics).We briefly describe here some of this research and we classify it by proposing three alternative viewpoints on the very same null-collision concept: an intuitive, physical point of view, called similitude; a viewpoint built on the probability theory, where the null-collision method is seen as rejection sampling; and a more formal writing where the nonlinear exponential function is expanded into an infinite sum of linear terms.By formulating the null-collision concept under three distinct formalisms, our intention is to increase the reader’s awareness of its flexibility.The idea defended and illustrated in this paper is that the ability to explore null-collision algorithms under their different forms has often led to a broadening of the solution space when facing difficult problems, including ones where the Monte Carlo method was consensually considered inapplicable
Cobalt catalysts on carbon-based materials for Fischer-Tropsch synthesis: a review
No full textInternational audienceThis review analyzes the literature from the 80’s to the beginning of 2020 and covers the use of carbon materials as supports for cobalt-based catalysts used in the Fischer Tropsch reaction. The article is composed of two sections. The first one details the reactivity of carbon supported cobalt catalysts with a particular focus on: i) reaction mechanisms and conditions, ii) effect of cobalt particle size, iii) confinement effects, iv) hydrogen spillover, and v) deactivation mechanisms. In the second part, the different methods of Co/C catalyst preparation are presented, and the influence of several parameters such as the type of supports and its functionalization, the metal loading or the catalyst activation on the catalytic performances is discussed. This work also provides some perspectives in the field
Surface energy determination of fibres for Liquid Composite Moulding processes: method to estimate equilibrium contact angles from static and quasi-static data
No full textInternational audienceInterest in eco-composites incorporating elements from recycling is growing to reduce the carbon footprint of final products. Therefore, the characterisation surface properties of recycled fibres is of first importance. However, in order to maximise the service properties and facilitate their development, chemical surface treatments can be made in order to improve fibres compatibility with resins. For a better understanding of the behaviour of these new reinforcements during Liquid Composite Moulding processes (LCM), surface analysis and wetting properties are studied. However, this type of analysis, using the Owens and Wendt relation and based on tensiometric methods, requires special procedures, specifically for estimation of the contact angle. Based on two tensiometric methods, carbon and basalt fibres with different sizing are characterised in first approach, in order to be able to address recycled materials in further studies. The main contribution of this study is to evaluate the error in surface energy and its components determination associated to the measurement of an alleged equilibrium contact angle deriving from static or quasi-static data
Characterization of Steam Gasification Biochars from Lignocellulosic Agrowaste Towards Soil Applications
No full textInternational audienceThe main objective of this work was to analyze the physico-chemicals properties of biochars produced from the steam gasification of different lignocellulosic agrowastes, and determine the suitability of these materials to be used in soil amendment and remediation applications. Steam gasification biochars from three lignocellulosic agrowastes were extensively characterized. Coconut shells (CS), bamboo guadua (BG), and oil palm shells (OPS) were chosen as raw materials, considering their different macromolecular structure and inorganic composition. The biochars composition, morphology, pH, acid neutralization (ANC) and cation exchange (CEC) capacities, as well as their mineral release at different conditions were evaluated and compared. The experimental results showed that the inorganic content and composition of the biochars have a stronger impact on their properties for soil applications, in comparison to their organic composition and morphology. In particular, BG biochar, the sample with the highest mineral content, exhibited the most notable cation exchange (45 cmolc/kg) and acid neutralization capacities (125 cmol H+/kg), together with the greatest release of plant micro and macro-nutrients. In the case of biochars with low mineral content, higher CEC and ANC were most related to the presence of oxygen-containing functional groups in their surface. Considering that agricultural residues come from numerous sources and activities, the presented results usefully contribute to the comprehension of the relationship between the raw biomass characteristics, the physico-chemical properties of steam gasification biochars, and their expected performance in soil applications, opening a new promising valorization pathway for these materials
Experimental studies of hydrothermal liquefaction of kitchen waste with H + , OH − and Fe 3+ additives for bio-oil upgrading
No full textInternational audienceKitchen waste (KW) has gradually become a prominent problem in municipal solid waste treatment. Hydrothermal liquefaction (HTL) is a promising method used to make fuel oil from food and KW. However, the upgrading of bio-oil is particularly important for the sake of industrial reuse. In this study, the KW from university restaurants was subjected to HTL experiments in order to study theoretical feasibility. With the change of conversion temperature and residence time, the optimal conversion working conditions in this study were determined according to the quality and yield of the bio-oil. Moreover, the bio-oil upgrading effects of different additives (hydrogen chloride, sodium hydroxide, and iron(III) chloride) on the HTL of KW were studied. Alkaline additives have an inhibitory effect on the bio-oil yield and positive effect on coke yield. Acidic additives and iron (Fe)-containing additives can promote bio-oil yield. As an important aspect of upgrading, the effect on the nitrogen content of bio-oil with additives was revealed. The alkaline and Fe-containing additives have little effect on reducing the viscosity of the bio-oil while with the appropriate ratio (2.5 mol•kg−1) of acidic additives to the raw material, the static and dynamic fluidity of the oil phase products are reduced to about 0.1 Pa•s
Système d'aide à la décision pour le diagnostic industriel qualitatif
No full textOver the past several years, industrial companies have been under unprecedented pressure to adapt to different variations in demand, supplier problems or simply their own intrinsic changes. This need for adaptation requires the ability to be able to quickly and effectively analyze the current state of health of the company. However, the collecting, processing and reporting of the data and the quantitative information necessary for such diagnoses is much slower than the speed of change now challenging companies. This is why the aim of this research work is to propose a rapid industrial diagnostic methodology, which is based on a semi-automated approach and qualitative information. After having carried out a state of the art on the existing methods in terms of industrial diagnosis in the first chapter, we chose to focus our scientific and technical proposal on the Thinking Processes method from the Theory of Constraints. This method, which inherits the theoretical foundations associated with graph theory and Bayesian networks, has many potential advantages for conducting a qualitative diagnosis of a production system of goods or services. Unfortunately, it also has many pitfalls, such as the high level of expertise and experience required to implement it, or the excessive amount of time required for its deployment. The second chapter thus focuses on the formalization and structuring of an original approach to industrial diagnosis inspired by the Thinking Processes method. It also develops an original functional architecture and a technical architecture to structure a decision support system capable of supporting the developed approach. Finally, it defines and develops a software prototype called DOSSARD to concretize the elements defined in this decision support system. The third chapter formalizes, in the form of a graph-oriented knowledge base, the validation and enrichment of a generic Current Reality Tree adapted to the characterization of production systems that use manufacturing to stock (MTS). It also develops a generic Current Reality Tree (knowledge base) that is completely new, adapted to production systems that use manufacturing to order or project (ETO). The fourth chapter describes how these contributions were tested and validated on about fifty industrial cases in order to demonstrate their added value and also identify their limitations. The proposed approach and the associated decision support system were successful in achieving the expected results. In particular, they made it possible to significantly accelerate the speed of diagnosis while improving the relevance and robustness of the final product. In the concluding chapter, the manuscript offers a set of promising research perspectives. First, while many field experiments were conducted as part of this research work, most of the cases concerned stock production systems (STDs). The proposal made therefore remains to be validated more widely on cases relating to production to order or project (ETO) and above all, it could be extended to the many other existing systems, such as assembly to order (ATO), configuration to order (CTO) or distribution, for example. Finally, even though the number of industrial cases mobilized for this study was high, it was still too limited to consider an in-depth testing of the knowledge bases and associated inference rules.Les entreprises industrielles sont soumises depuis plusieurs années maintenant à une pression sans précédent pour s’adapter aux différentes variations de la demande, aux aléas fournisseurs ou tout simplement à leurs changements intrinsèques. Ce besoin d’adaptation nécessite d’avoir la capacité de pouvoir analyser rapidement et efficacement l’état de santé actuel de l’entreprise. Or, le temps de collecte, traitement et restitution de données et informations quantitatives nécessaires à de tels diagnostics, est plus lent que les changements auxquels sont confrontés les entreprises. C’est pourquoi le but de ce travail de recherche a été de proposer une méthodologie de diagnostic industriel rapide, qui soit basée sur une approche semi-automatisée et des informations qualitatives. Après avoir réalisé dans un premier chapitre un état de l’art sur les méthodes existantes en termes de diagnostic industriel, nous avons finalement fait le choix d’axer notre proposition scientifique et technique sur la méthode des Thinking Processes issue de la Théorie des Contraintes. Cette méthode qui hérite des fondements théoriques associés à la théorie des graphes et aux réseaux bayésiens, présente de nombreux atouts potentiels pour mener un diagnostic qualitatif d’un système de production de biens ou de services. Malheureusement, elle présente aussi de nombreux écueils tels que le haut niveau d’expertise et d’expérience requis pour la mettre en œuvre ou le délai très long nécessaire à son déploiement. Le second chapitre s’intéresse ainsi à la formalisation et à la structuration d’une démarche originale de diagnostic industriel inspiré de la méthode des Thinking Processes. Il développe également une architecture fonctionnelle et une architecture technique originales permettant de structurer un système d’aide à la décision capable d’accompagner la démarche développée. Enfin, il définit et développe un prototype logiciel appelé DOSSARD permettant de concrétiser les éléments définis dans le système d’aide à la décision précédent. Le troisième chapitre, lui, formalise sous forme de base de connaissances orientée graphe, la validation et l’enrichissement d’un arbre des réalités actuelles générique adapté à la caractérisation des systèmes de production de type fabrication sur stock (MTS). Il élabore également un arbre des réalités actuelles générique (base de connaissances), totalement nouveau, adapté aux systèmes de production de type fabrication sur commande ou projet (ETO). Le quatrième chapitre décrit comment ces contributions ont été testées et validées sur une cinquantaine de cas industriels afin de démontrer leur valeur ajoutée et d’identifier également leurs limites. Il en résulte que la démarche proposée et le système d’aide à la décision associé permettent bien d’atteindre les résultats escomptés. Notamment ils permettent d’accélérer très significativement la vitesse de diagnostic tout en améliorant la pertinence et la robustesse du livrable produit. Enfin, dans un dernier chapitre conclusif, le manuscrit propose un ensemble de perspectives de recherche prometteuses. D’abord, si de nombreuses expérimentations terrain ont pu être menées dans le cadre de ce travail de recherche, l’essentiel des cas portaient sur des systèmes de production sur stock (MTS). La proposition faite reste donc à valider plus largement sur des cas de production sur commande ou projet (ETO) et surtout, elle reste à étendre aux nombreux autres systèmes existants tels que l’assemblage à la commande (ATO), la configuration à la commande (CTO) ou encore la distribution par exemple. Enfin, même si le nombre de cas industriels mobilisés pour cette étude est élevé, il demeure beaucoup trop limité pour envisager éprouver véritablement les bases de connaissances et les règles d’inférence associées
Comportement thermomécanique des poudres pharmaceutiques lors des processus de compactage
No full textDry granulation / roller compaction is an enlargement process by agglomeration of the primary powders without adding any solvent. This operation makes it possible to homogenize the properties of pharmaceutical formulations and improve the flow properties necessary for the manufacture of tablets using rotary presses. In this process, temperature variations in the product are rarely considered. However, recent studies have shown that for pharmaceutical powders, such variations can lead to changes in mechanical and physico-chemical properties. In this thesis, a new method based on in-line measurements of powders temperature compacted by a roller press is developed using an infrared camera. Temperature distributions on the surface of the compact were determined using infrared radiation emitted by the compact after leaving the gap. These distributions showed a correlation with the microstructural properties of the compact, confirming the potential of this procedure in monitoring product quality. To understand the potential sources of the heating of pharmaceutical products in dry granulation, a heat balance model was established in anticipation of the numerical simulation of the thermomechanical coupling of the process by finite element method. As the thermal properties of the compact depend on the relative density, the thermal conductivity and the specific heat were characterized for two model pharmaceutical excipients. In addition, the impact of dry granulation on the rearrangement and densification of granules in die compression is studied using a mathematical model (Cooper-Eaton) which allowed to a better understanding of the contribution of dry granulation to tableting process.Le procédé d’homogénéisation par granulation sèche/compactage à rouleaux, consiste principalement à agrandir la taille des particules par agglomération des poudres primaires. Cette opération permet d’homogénéiser les propriétés de formulations pharmaceutiques et d’améliorer les propriétés d’écoulement nécessaires pour la fabrication de comprimés par des presses rotatives. Dans ce procédé, les variations de températures dans le produit sont rarement considérées. Cependant, des études récentes ont montré que pour des poudres pharmaceutiques, de telles variations peuvent entrainer des changements de propriétés mécaniques et physico-chimiques. Dans cette thèse, une nouvelle méthode de mesure en ligne des températures de poudres compactées par une presse à rouleaux est développée en utilisant une caméra infrarouge. Les distributions de températures à la surface du compact ont été déterminées à l’aide du rayonnement infrarouge émis par le compact après avoir quitté l'espace entre les rouleaux. Ces distributions ont montré une corrélation avec les propriétés microstructurales du compact, ce qui confirme le potentiel de cette procédure dans la surveillance de la qualité du produit. Pour comprendre les sources potentielles de l’échauffement des produits pharmaceutiques en granulation sèche, un modèle de bilan thermique a été établi en prévision de la simulation numérique du couplage thermomécanique du procédé par méthode des éléments finis. Comme les propriétés thermiques du compact dépendent de la densité relative, la conductivité thermique et la chaleur spécifique ont été caractérisées pour deux excipients pharmaceutique modèles. Par ailleurs, l’impact de la granulation sèche sur le réarrangement et la densification des granulés en compression en matrice, est étudié à l’aide d'un modèle mathématique (Cooper-Eaton) et permet de mieux comprendre l’apport de la granulation sèche à la compression des comprimés