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Possibilistic Pareto-dominance approach to support technical bid selection under imprecision and uncertainty in engineer-to-order bidding process
No full textInternational audienceSuccessful bidding involves defining relevant technical bid solutions that conform to the customers' requirements, then selecting the most interesting one for the commercial offer. However, in Engineer-To-Order (ETO) industrial contexts, this selection process is complicated by issues of imprecision, uncertainty and confidence regarding the values of the decision criteria. To address this complexity, a Multi-Criteria Decision Making (MCDM) support approach is proposed in this study. This approach is based on possibility theory and the Pareto-dominance principle. It involves three main stages. First, a method is proposed to automatically model the values of the decision criteria by possibility distributions. Second, four possibilistic mono-criterion dominance relations are developed to compare two solutions with respect to a single decision criterion. Finally, an interactive method is devised to determine the most interesting technical bid solutions with respect to all the decision criteria. The method is applied to the design of a technical bid solution of a crane. The results show that this approach enables bidders to select the most interesting solution during a bidding process, while taking into account imprecision, uncertainty and their own confidence regarding the values of the decision criteria
Designing Valid Humanitarian Logistics Scenario Sets: Application to Recurrent Peruvian Floods and Earthquakes
No full textInternational audienceLiterature about humanitarian logistics (HL) has developed a lot of innovative decision support systems during the last decades to support decisions such as location, routing, supply, or inventory management. Most of those contributions are based on quantitative models but, generally, are not used by practitioners who are not confident with. This can be explained by the fact that scenarios and datasets used to design and validate those HL models are often too simple compared to the real situations. In this chapter, a scenario-based approach based on a five-step methodology has been developed to bridge this gap by designing a set of valid scenarios able to assess disaster needs in regions subject to recurrent disasters. The contribution, usable by both scholars and practitioners, demonstrates that defining such valid scenario sets is possible for recurrent disasters. Finally, the proposal is validated on a concrete application case based on Peruvian recurrent flood and earthquake disasters
Degradation of carbon fiber reinforced peek composite under different atmospheres
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Effect of dry ball milling process on curcumin crystals and its impact on physico-chemical and biopharmaceutical properties
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Streaming et sono-chiluminescence : confrontation théorie/expérience
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Biochar From Pyrogasification As Catalysts For Hydrogen Production: Thermodynamic Behaviour
No full textInternational audienceDemand for hydrogen is increasing. To meet this demand, H2 can be produced through thermoconversion ofbioresources [1]. This requires catalysis. Through literature review, inorganic elements were identified and classified. The objective of this work is to evaluate thermodynamic behaviour of biosourced biochar (BC) produced through pyrogasification to predict inorganic element content and stability when using this char as a catalyst in H2 production
Study of the pyrolysis reaction mechanisms for dust explosion
No full textDust explosion of organic powders involves particles heating, pyrolysis, oxidation of pyrolytic gases and flame propagation. This work focused on the pyrolysis step, which can be rate-limiting during explosions. To better represent the pyrolysis stage, flash pyrolysis of four organic dust clouds (microcrystalline cellulose, wheat starch, oak and douglas fir) were carried out in a Godbert-Greenwald furnace from 700 to 900ᵒC, at a heating rate of 1000ᵒC.s-1, a solid residence time between 150 and 250 ms and vapour residence time in less than 2 s. Tar condensates analysis verifies the production of levoglucosan as the major product for cellulose and wheat starch pyrolysis. Optic image analysis and residual volatile matter content determination with TGA confirmed low conversions of solid residues. The major gaseous components identified were H2 (Hydrogen), CO (Carbon mono-oxide), CH4 (methane), CO2 (carbon dioxide) along with small yields of C2H2 (acetylene), C2H4 (ethylene) and traces of C6H6 (benzene). The effect of reactor temperature on gas compositions was studied. Experimental results indicated H2, CO, and CH4 increased with increasing reactor temperature whereas CO2 showed a contrary trend. C2H4 and C6H6 also increased at elevated reactor temperature but C2H2 showed a similar trend as CO2. Minimum Ignition Temperature (MIT) test results indicated the smallest hot surface temperatures that could be an ignition source for cellulose, wheat starch and oak dust explosions. Pyrolytic product analysis helped explain the pyrolysis behaviour of organic dust in the Godbert-Greenwald setup, a predictive model can be generated to predict the pyrolysis reaction rate of the dust in another work
Tool for Nervousness Analysis in a Rolling Planning Environment via Historical Data
No full textPart VIII - Modern Analytics and New AI-Based Smart Techniques for Replenishment and Production Planning Under UncertaintyInternational audienceThis paper analyses the modifications of plans exchanged between supply chain actors in a tactical planning rolling horizon process. A particular focus is on the changes of planned quantities in order to respond to fluctuating demand or to adapt to internal contingencies of the organization. They create instability and nervousness in the planning system. This paper presents a data-driven study to compare the behavior of planning decision makers in a context of certain and uncertain demand. We show through simulation and statistical analysis the effect of decision characteristics of one actor on the system nervousness and the resulting uncertainty for the other actors
Analyse multi-échelle du chargement thermomécanique induit au cours du perçage du Ti-6Al-4V
No full textThe drilling process is a complex operation generating high forces, torques and temperatures in a very localized and confined area. This thermomechanical loading can trigger early damage to the tools and impair the generated surfaces, especially when drilling Ti6Al4V, a material that is difficult to machine. The objective of this thesis is to improve the understanding of the involved cutting phenomena and provide a reliable and relevant evaluation of the loadings induced by the passage of the tool on the wall of the drilled hole. Experimentally, due to the high speeds and the difficult access to the cutting zone, obtaining reliable and quality information is a challenging task. The experimental part of this thesis therefore focus on the implementation and realization of tests for the measurement of thermomechanical fields at different scales of study. This multi-scale approach enables to identify the phenomena involved at different levels, but also to compare the studies at different scales in order to validate them and allow the change of scale. In addition, a numerical study is conducted. Faced with experimental difficulties, numerical modeling appears to be a relevant alternative in the assessement of the desired data. The approach adopted here is to couple it to the experimental strategy in order to develop a robust multi-scale model of Ti6Al4V drilling. This modeling is based on behavior and damage laws presenting an explicit coupling of thermal and mechanical phenomena, as well as on a fine determination of friction laws and partition coefficients. Finally, a comparison of the numerical and experimental results is carried out at each scale of study and enabled to conclude on the relevance of the proposed numerical model.Le procédé de perçage consiste en une opération complexe générant d’importants efforts, couples et températures au sein d’une zone très localisée et confinée. Ce chargement thermomécanique peut conduire à l’usure prématurée des outils et à l’altération des surfaces générées, notamment lors du perçage du Ti6Al4V, matériau difficilement usinable. L’objectif de ces travaux de thèse est de fournir les clés pour une meilleure compréhension des phénomènes en jeu et une évaluation fiable et pertinente de ce chargement induit par le passage de l’outil sur la paroi du trou percé. Expérimentalement, du fait des vitesses élevées et de la zone de coupe difficile d’accès, obtenir des informations fiables et de qualité constitue un réel défi. Le volet expérimental de cette thèse a donc porté sur la mise en place et la réalisation d’essais pour la mesure de champs thermomécaniques à différentes échelles d’étude. Cette approche multi-échelle a permis d'identifier les phénomènes mis en jeu à différents niveaux, mais aussi de confronter les études aux différentes échelles afin de les valider et de permettre le changement d'échelle. En complément, une étude numérique est menée. Face aux difficultés expérimentales, la modélisation numérique apparaît comme une alternative pertinente pour l’évaluation des données souhaitées. La démarche adoptée ici est de la coupler à la stratégie expérimentale en vue d'élaborer une modélisation multi-échelle du perçage du Ti6Al4V qui se veut robuste. Cette modélisation est basée sur des lois de comportement et d'endommagement présentant un couplage explicite des phénomènes thermiques et mécaniques, ainsi que sur une détermination fine des lois de frottement et des coefficients de partage. Finalement, une confrontation des résultats numériques et expérimentaux est réalisée à chaque échelle d’étude et a permis de statuer sur la pertinence du modèle numérique proposé