Portail HAL IMT Mines Albi
Not a member yet
5440 research outputs found
Sort by
Automated unsupervised ontology population system applied to crisis management domain
No full textInternational audienceAs crisis are complex systems, providing an accurate response to an ongoing crisis is not possible without ensuring situational awareness. The ongoing works around knowledge management and ontologies provide relevant and machine readable structures towards situational awareness and context understanding. Many metamodels, that can be derived into ontologies, supporting the collect and organization of crucial information for Decision Support Systems have been designed and are now used on specific cases. The next challenge into crisis management is to provide tools that can process an automated population of these metamodels/ontologies. The aim of this paper is to present a strategy to extract concept-instance relations in order to feed crisis management ontologies. The presented system is based on a previously proposed generic metamodel for information extraction and is applied in this paper to three different case studies representing three different crisis namely Ebola sanitarian crisis, Fukushima nuclear crisis and Hurricane Katrina natural disaster
Alumina Failure and Post-failure Oxidation in the NiCoCrAlY Alloy System at High Temperature
No full textInternational audienceThis paper examines the oxidation behavior of thin specimens of cast NiCoCrAlY alloys at 1150 • C through successive stages, from Al 2 O 3 growth to complete alloy conversion to oxide. Five alloy compositions were used, with varying fractions and compositions of γ and β. The time evolution of the alloy composition during Al 2 O 3 growth was simulated using the DICTRA module of Thermo-Calc, and calculated analytically in the approximation of flat profiles. Simulated and experimental profiles were found to be in good agreement, indicating that the phase equilibrium and mass balance were correctly reproduced in the simulations. Local variations of alloy composition were observed in thinner specimens and found to be comparable with the variations expected from the uncertainty on the initial specimen thickness. The variations observed in the time-to-Al 2 O 3 failure were greater than expected on this basis, suggesting that additional sources of variability were in effect. Alumina failure was followed by the growth of a Cr 2 O 3 layer at the alloy-scale interface. Similarly, Cr consumption eventually led to Cr 2 O 3 failure, and Ni-and Co-containing spinel oxide formed, converting the Cr 2 O 3 at the alloy-scale interface and the Al 2 O 3 at the scale-gas interface. The remaining NiCo alloy was then converted to (Ni,Co)O. This sequence occurred without abrupt increase of the mass gain, due to the continued presence of the remnant Al 2 O 3 layer, and to the small amount of metal left to oxidize when the (Ni,Co)O eventually broke through the scale. The evolution of the scale composition throughout the oxidation stages is discussed based on an analysis of the thermodynamic conditions at the alloy-scale interface
Managing events to improve situation awareness and resilience in a supply chain
No full textInternational audienceThis paper aims at improving supply chain resilience by applying a model- and event-driven architecture from the crisis management field: the AIC information system which Acquires, Interprets and Contextualizes events. It begins with a literature review on information systems able to process events in order to improve situational awareness within supply chains. It concludes that supply chain managers still lack a decision support system able to access new information in near real time. The paper describes the components of the AIC information system, and the implications for a supply chain use case. By testing the architecture on a pharmaceutical supply chain, we assess the accuracy, cost and speed of the detection of new risks. These works are made possible by the use of several data streams aggregated into a single decision-making platform. This supports the claim for a more connected supply chain. Our contributions make crisis management knowledge available to supply chain management and help improving resilient decision-making in a fast changing context
Validation d’un modèle numérique de la coupe oblique du Ti-6Al-4V par mesures de champs thermomécaniques couplées
No full textNational audienceDans l’optique de maitriser le procédé de coupe, les travaux réalisés au cours d’une thèse précédente ont permis de développer des lois de comportement, d’endommagement et de frottement traduisant les couplages thermomécaniques et de les implémenter au sein d’un modèle éléments finis du procédé de coupe orthogonale du Ti6Al4V. Cette présente étude porte sur l’adaptation de ces lois matériaux au cas de la modélisation de la coupe oblique du Ti6Al4V. En vue de la valider, une confrontation entre les résultats numériques et des données expérimentales pertinentes est mise en œuvre. Pour cela, des mesures in-situ de champs thermomécaniques sont réalisées à l’aide de caméras rapide et infrarouge au cours d’essais de coupe oblique du Ti6Al4V. Cette étude constitue une première étape dans l’analyse de la capacité du modèle à traduire fidèlement le comportement du matériau sous diverses conditions de coupe notamment en termes de morphologie des copeaux (continus, festonnés) en coupe oblique
Molten salt pyrolysis of biomass: The evaluation of molten salt
No full textInternational audienceTo identify the performance and mechanism of variant molten salts during biomass pyrolysis in molten salt, the thermogravimetric and differential scanning calorimetry (TG-DSC) analyzer, fixed-bed reactor and thermodynamic equilibrium simulation were applied to study the thermal melting characteristics and stability of molten salt as well as the selectivity for biomass pyrolysis products. The KCl-ZnCl2 is appropriate for the preparation of H2-rich gas and the carbon material with abundant mesoporous structure due to its activation effect. At 850 °C, the pyrolysis gas obtained from KCl-ZnCl2 contained 42.22 vol% H2 with the H2/CO ratio reaching 1.69. The carbonates demonstrated excellent improvement for the gas composition of biomass pyrolysis products, with 75.43 vol% and 70.52 vol% syngas (H2 + CO) collected from the Li2CO3-K2CO3 and Li2CO3-Na2CO3-K2CO3 pyrolysis systems at 850 °C respectively. With the presence of carbonates, the bio-oil and char prepared by biomass pyrolysis also achieved better quality. The thermodynamic simulation revealed the shifting (formation of Li2O) of molten salt composition during biomass pyrolysis. The interaction between Li2CO3 and char under high temperature explained the high yield of CO in pyrolysis gas products, also resulted in the consumption of salts and limited the sustainable use of the molten salt pyrolysis system
Features of Structure Formation in an Al–Fe–Mn Alloy upon Crystallization with Various Cooling Rates
No full textInternational audienceSpecific features of the microstructure formation of an Al–2.5% Fe–1.5% Mn alloy owing to the cooling rate during casting and during laser melting are studied in this work. An analysis of the microstructure in the molten state shows that, with an increase in the cooling rate during crystallization from 0.5 to 940 K/s, the primary crystallization of the Al6(Mn,Fe) phase is almost completely suppressed and the volume of the nonequilibrium eutectic increases to 43%. The microstructures of the Al–2.5% Fe–1.5% Mn alloy after laser melting are characterized by the presence of crystals of an aluminum matrix of a dendritic type with an average cell size of 0.56 μm, surrounded by an iron-manganese phase of eutectic origin with an average plate size of 0.28 μm. The primary crystallization of the Al6(Mn,Fe) phase is completely suppressed. The formation of such a microstructure occurs at cooling rates of 1.1 × 104–2.5 × 104 K/s, which corresponds to the cooling rates implemented in additive technologies. At the boundary between the track and the base metal and between the pulses, regions were revealed consisting of primary crystals of the Al6(Mn,Fe) phase formed by the epitaxial growth mechanism. The size of the primary crystals and the width of this zone depends on the size of the eutectic plates and the size of the dendritic cell located in the epitaxial layer. After laser melting, the Al–2.5% Fe–1.5% Mn alloy has a high hardness at room temperature (93 HV) and, after heating up to 300°C, it has a high thermal stability (85 HV). The calculated yield strength of the Al–2.5% Fe–1.5% Mn alloy after laser melting is 227 MPa. The combination of its ultrafine microstructure, high processibility during laser melting, hardness at room and elevated temperatures, and high calculated yield strength make the Al–2.5% Fe–1.5% Mn alloy a promising alloy for use in additive technologies
Management of crisis exercises in Virtual Reality
No full textInternational audienceWhen we consider the question of crisis management, training and practising exercises are regularly requested to be ready for any possible crisis. Unfortunately, these exercises come with many disadvantages, especially the cost, the complexity of implementation, the lack of replicability, and agility. The project aims to create customizable Virtual Reality simulations in existing environments. In this article, we detail our approach dedicated to using VR for a fire in a University Research Lab involving a game master managing the scenario, five people, interacting and acting conjunctly within this environment, and several coordinators the rescue process
Rheological characterization of sludge in divided granular-like and pasty states using a granular rheometer
No full textInternational audienceStructural changes during sludge treatments impact flowability and raise severe technical issues. In this study, the sludge consistency is analysed using the thread rolling test. Transition from pasty to granular-like material occurs at a total solid (TS) content of 43 wt%. A granular rheometer is used to characterize sludge's flowability over a wide range of TS content. The typical powder-like behaviour is recorded whatever the TS contents. All the shear stresses/consolidations curves exhibit a linear increase, highlighting the contribution of frictional interactions. Fitting the Mohr-Coulomb failure criterion to these curves emphasizes a substantial rise of frictional interactions from 43 wt%. Flow functions are determined from the Mohr's circle stress analysis. According to the classification of powder flowability, sludge behaviour is analogous to that of very cohesive powders for 25.5 < TS < 43 wt% while for lower and higher TS contents, the material behaves like cohesive powders
Product⋎service system configuration: a generic knowledge-based model for commercial offers
No full textInternational audienceAt a time when modes of consumption are rapidly evolving, consumer attitudes and expectations are changing. Today, customers want more and more products and services that can be customised to their needs. Furthermore, they are more willing to pay for usage of a product rather than ownership. On the other hand, companies are adding more and more services to the products they are bringing to market in order to create added value and differentiate themselves from their competitors. To adapt to these new market trends, companies now have to offer their customers a more sophisticated catalog of solutions, in both product and services, including all conceivable combinations of the two. The aim of this article is to propose a generic knowledge-based model, dedicated to commercial offer configuration which is able to cope with the whole variety of solutions a company can deliver. To our knowledge, although some works on product configuration, service and product-service system configuration exist, none of them is generic enough to support product, service and product-service configuration at the same time when defining commercial offers. In this article, after giving a state-of-the-art assessment of product and service configurations, the need for a generic model able to cover the whole range and diversity of commercial offers is established, a knowledge-based model is defined and its relevance is demonstrated on seven use-cases coming from secondary and tertiary sector companies
