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Effect of porosities on brazed martensitic steel tensile properties: 2D and 3D pre-mortem vs post-mortem characterizations
No full textInternational audienceA quantitative investigation of the porosity and its effects on mechanical properties was conducted on brazed materials presenting macroscopically brittle behavior with various defect levels. Three different techniques for evaluating the porosity and the fracture mechanisms were compared: (i) pre-mortem X-ray computed tomography (XCT), (ii) post-mortem laser scanning confocal microscopy (LSCM), and (iii) post-mortem scanning electron microscopy (SEM). The apparent surface area of the pores was evaluated by segmenting the height maps produced by LSCM and the electron backscattered images produced by SEM. The results show good agreement for different porosity levels. The LSCM height maps for opposite fracture faces were virtually stitched together in order to reconstruct three-dimensional (3D) images of the whole brazed joints. These proved to be similar to the XCT 3D segmented images, yet with some discrepancies due to local plastic deformation. Quantitative volume fraction and spatial distribution of pores were assessed as well as the identification of fracture mechanisms. Interestingly, it was noted that two specimens with different ultimate tensile strengths presented the same porosity amount, but different distributions. Two distinctive features were identified in the broken specimens: plastically teared pillars and walls that were separating the pores before fracture, and plateaus of approximately constant height with micro-sized dimples showing interfacial fracture. Although the specimens exhibited a macroscopic brittle behavior, these features are characteristic of ductile fracture. The most probable scenario for fracture was conjectured as follows: (i) Final fracture occurs in the near-surface region of the samples and conversely early damage develops in the volume, (ii) Interfacial fracture within plateaus is responsible of the rupture/strength of the brazed specimen but detrimental effect is induced by the tearing if highly voided regions are present in the joint
Ceramics from Municipal Waste Incinerator Bottom Ash and Wasted Clay for Sensible Heat Storage at High Temperature
No full textInternational audienceAlthough work has been done to understand the sintering behavior and properties of Municipal Waste Incinerator Bottom Ashes to produce sintered (Bethanis et al. in Ceram Int 28:881–886, 2002; Cheeseman et al. in Resour Conserv Recycl 43:147–162, 2005; Bourtsalas et al. in Waste Manag 45:217–225, 2014; Taurino et al. in J Eur. Ceram Soc 37:323–331, 2017) or sinter-crystallized (Schabbach et al. in J Non Cryst Solids 357:10–17, 2011; Barbieri et al. in J Non Cryst Solids 354:521–528, 2008) ceramics, most of the trials reported in the literature focuses on the use of extensively milled bottom ashes powders (particle size around 1–50 µm), using processes that might not be easily transferable to industrial production at reasonable cost, and producing small cylinders with uniaxial compression technique on powders. This paper summarizes the development process of an extruded ceramic material made of gross-milled bottom ashes and waste clay, designed to be easily mass-produced using production capacities available in the building bricks industry, to be used as a high-temperature thermal energy storage material, which represents an alternative to the petrurgic ceramic previously developed for this application (Py et al. in J Sol Energy Eng 133:031008, 2011; Kere et al. in Int Conf Eng Waste Biomass Valoris, Porto, 2012; Py et al. in Stockage de l’ énergie: énergie thermique, stockage thermique haute température). Post-treated incinerator bottom ashes from a commercial incinerator has been collected, characterized and processed to form ceramic materials, using clay as a binder. Ashes were milled, dried, and mixed with various amounts of an illitic clay (produced as washing mud by a quartz quarry) prior to extrusion (cylindrical pellet) and firing at different temperatures, ranging from 1100 to 1120 °C. The sintered samples have been characterized in terms of density, mechanical strength, thermal capacity and thermal conductivity. Their mineral structure has also been studied. This work follows a study on the feasibility about the production of MWIBA based slabs with uniaxial compaction, and can be seen as an improvement regarding the shaping of the green bodies, more compatible with thermocline thermal energy storage process. The resulting sintered ceramics exhibit interesting properties such as relatively high mechanical resistance and low thermal conductivity, along with moderate density. These properties allow envisioning the use as filler material for thermocline thermal storage systems, especially considering the simplicity of the production process, relying on dry gross milling (jaw-mill), and firing at a temperature reachable within the building bricks and tiles industry. Production of adequate pieces to be used as thermal storage media seems however more relevant, the small size limiting the impact of sintering heterogeneities (formation of black bodies due to high content in fluxing agents like sodium and potassium)
Model Transformation from CBM to EPL Rules to Detect Failure Symptoms
No full textInternational audienceThe increasing complexity of modern systems, cost reduction policies and ever increasing safety requirements are bringing new challenges to the maintenance domain. In many fields, periodic maintenance actions become either insufficient or too expensive. In this context, Condition-Based Maintenance (CBM) strategies, and Prognostics and Health Management (PHM) in particular, are offering an interesting alternative by allowing systems to be maintained only when needed. These strategies rely on a constant monitoring and analysis of the systems operating conditions in order to detect and identify a failure when it occurs and even sometimes beforehand.Nowadays, two main approaches are explored to detect failures in PHM solutions: one based on machine learning, the other based on expertise and capitalised system knowledge. This work proposes to combine a Complex Event Processing (CEP), to manage incoming data’s volumetry and velocity, with an Expert System (ES) in charge of exploiting the capitalized knowledge. This paper focuses on the configuration of a CEP from rules contained in a CBM ES using a Model Driven Architecture (MDA). This configuration is a challenge, especially regarding the management of rules with temporal parameters and the need for intermediate results to deal with the rule’s complexity
Ingénierie des risques à base de connaissances pour la relation client fournisseur
No full textOur thesis work takes place within the scope of the customer-supplier relationship. More specifically, we are interested in the bidding process that the supplier follows to respond to a customer need or a call for tenders. Indeed, when responding to a call for tenders, the elaboration of an offer is a complex process, generally characterized by partial and imprecise information as well as a limited response time. At the end of the elaboration of the offer, are provided (i) a technical solution describing the system or the product to be realized as well as (ii) a delivery process describing the tasks to be realized to obtain and deliver the ordered system or product. We consider tangible systems or products mainly resulting from manufacturing processes (cranes, machine tools, engines...) and requiring at least one more or less consequent engineering activity. The considered situation is therefore an industrial situation of the engineering to order (ETO) type. We also consider that the elaboration of the offer is limited to a form of preliminary design. This generates the risk that the supplier will not be able to finalize, realize and supply the system ordered by the customer, respecting what was promised in the offer in terms of costs and deadlines. Adopting the point of view of bidding companies, this thesis work focuses on the development of knowledge-based tools to assist in the risk engineering of the process of leading a product or system, from its design to its delivery. We propose firstly a risk knowledge model to formalize and capitalize risk knowledge when responding to a call for tenders. As a logical complement, we propose an approach for reusing the capitalized knowledge to help risk engineering in terms of risk identification, risk impact assessment and definition of mitigation treatments.Nos travaux de thèse se déroulent dans le cadre de la relation client-fournisseur. Nous nous intéressons plus précisément au processus d’élaboration d’offres que le fournisseur suit pour répondre à un besoin client ou à un appel d’offres. En effet, lors de la réponse à un appel d'offres, l'élaboration d'une offre est un processus complexe, généralement caractérisé par des informations partielles et imprécises ainsi qu’un temps de réponse limité. A l’issu de l’élaboration d’une offre, sont définis (i) une solution technique décrivant le système ou le produit à réaliser ainsi (ii) qu’un processus de réalisation décrivant les tâches à réaliser pour obtenir et livrer le système ou le produit commandé. Nous considérons des systèmes ou produits tangibles issus principalement de processus manufacturiers (grues, machines-outils, moteurs…) et nécessitant au moins une phase d’ingénierie plus ou moins conséquente. La situation considérée est donc une situation industrielle de type ingénierie à la commande (ETO). Nous considérons également que l’élaboration de l’offre se limite à une forme de conception préliminaire. Ceci génère le risque que le fournisseur ne soit pas capable de finaliser, réaliser et fournir le système commandé par le client, en respectant ce qui a été promis dans l’offre en termes de coûts et de délais. Adoptant le point de vue des entreprises soumissionnaires, ces travaux de thèse se concentrent sur l’élaboration d’outils à base de connaissances pour aider l'ingénierie des risques du processus de réalisation d’un produit ou d’un système, de sa conception à sa livraison. Nous proposons d’une part un modèle de connaissances liées aux risques permettant de formaliser et capitaliser toute connaissance liées aux risques lors de la réponse à un appel d’offres. En complément logique, nous proposons une approche de réutilisation des connaissances capitalisées pour aider à l’ingénierie des risques en termes : d’identification des risques, d’évaluations de leurs impacts et de définition de leurs traitements de mitigation
Séchage de gouttes comme vecteur pour les particules solides multi-constituants : étude expérimentale et modélisation à l’échelle de la goutte
No full textLiquid droplets are one of the major means of generation of solid particles with controlled. These templates are encountered with a variety of industrial processes, among them, spray drying. These tailored structures would meet the demand for particles with controlled properties, like improved kinetics, sustained release or controlled reactivity. The major scientific obstacle is the detailed description of the components distribution inside the droplet during drying, besides prediction of the final particle morphology. An experimental/modeling approach is undertaken in this thesis to understand how the drying conditions and the liquid formulation impact the final structure of the powders. The drying systems studied were sucrose-dextran and lactose-whey protein isolate aqueous solutions. The experimental work was firstly carried out at the lab-scale spray-dryer giving a reference picture of the possible particle morphologies for the drying systems. An experimental set-up was designed and developed to suspend a liquid droplet by a filament, from which the droplet mass variation over time could be accurately measured, giving fundamental insight into the drying process and allowing the analysis of the modification of the solid structures. A novelty explored at the droplet scale with an acoustic levitator was to apply an in situ Raman spectroscopy to assess the evolution of the spatial distribution of two components in drying droplets. Finally, a 2-D droplet drying model using Computational Fluid Dynamics was developed for allowing the assessment of the spatial distribution of the droplet components under a convective drying, until the formation of a crust. A sensitivity analysis was performed in order to show the influence of the experimental conditions on the drying kinetics and the component spatial distribution.Les gouttes liquides se sont avérées l’un des principaux vecteurs pour la génération de particules solides à propriétés contrôlées. Ce type de vecteur est utilisé dans plusieurs domaines industriels, y compris le séchage par atomisation. Le développement de ces particules structurées est poussé par la demande pour des particules à propriétés contrôlées, comme la cinétique de dissolution, le relargage contrôlé ou la réactivité. Le principal verrou scientifique est la description détaillée de la distribution des constituants au sein de la goutte pendant le séchage, en plus de la prédiction de la morphologie de la particule finale. L'objectif de cette thèse est de comprendre, par une approche couplée modélisation/expérimentation, comment les conditions de séchage et les formulations liquides impactent la structure de la poudre. L'étude expérimentale a d'abord été réalisée dans un sécheur par atomisation à l'échelle laboratoire pour la création d'une cartographie représentant les morphologies obtenues pour les deux systèmes de séchage. Un dispositif expérimental a été conçu de manière à étudier la formation d'une particule solide à partir d'une goutte suspendue par un filament, ce qui permet d'appréhender des éléments fondamentaux relatifs au séchage de la goutte ainsi que des aspects sur la modification de la structure solide. Une nouveauté explorée à l'échelle de la goutte avec un lévitateur acoustique consistait à appliquer la spectroscopie Raman in situ afin d'évaluer l'évolution de la distribution spatiale de deux composants lors du séchage de la goutte. Enfin, un modèle de séchage de goutte en 2-D avec la Dynamique des Fluides Numérique est conçu, ce qui permet de quantifier la distribution spatiale des composants de la goutte sous un séchage convectif, jusqu’à la formation de la croûte. Une analyse de sensibilité est réalisée de manière à montrer l'influence des conditions expérimentales sur la cinétique de séchage et la distribution spatiale des solutés
SAMUFLUX : une démarche outillée de diagnostic et d'amélioration à base de doubles numériques : application aux centres d'appels d'urgence de trois SAMU
No full textThe demand for emergency medical services has been significant and increasing over the last decade. In a constrained medico-economic context, the maintenance of operational capacities represents a strategic strake in front of the risk of congestion and insufficient accessibility for the population. Recent events such as the COVID-19 pandemic show the limits of the current system to face crisis situations. Reinforcement in human resources cannot be the only solution in front of this observation and it becomes unavoidable to build new organizational models while aiming at a quality of service allowing to answer 99% of the incoming calls in less than 60 seconds (90% in 15s and 99% in 30s MARCUS report and HAS recommendation October 2020). However, these models must take into account the great heterogeneity of EMS and their operation. In the light of these findings, the research work presented in this manuscript aims to evaluate the organizational effiectiveness and resilience of EMS in managing the flow of emergency telephone calls to deal with daily life and crisis situations. This evaluation allows us to propose and test new organizational schemes in order to make recommendations adpated to the particularities of emergency call centers. In a first part, we propose a methodology equipped for the diagnosis and improvement of emergency call centers. It can be broken down into two main parts: the study of data from emergency call centers, and then the design and use of a dual digital system. For each step of this methodology, we propose an associated tool. In a second part, we apply the first part of the methodology to our partner EMS data. The aim is to be able to extract information and knowledge from the telephony data as well as from the business processes for handling emergency calls. The knowledge thus extracted makes it possible to design a digital duplicate that is close to the real behavior of the EMS. Finally, in a third part, we use the material produced previously to model and parameterize a digital duplicate deployed on a discrete event simulation engine. It allows us to test several scenarios by playing on different call management organizations. Thanks to this, we make recommendations on the types of organizations to adopt in order to improve the performance of call centers.L’engorgement des structures d’urgence médicale est une réalité à laquelle les SAMU (Service d’Aide Médicale Urgente) n’échappent pas (5 à 15% d’augmentation des appels par an). De récents événements comme la pandémie de Covid-19 montrent les limites du système actuel pour faire face aux situations de crise. Le renfort en moyens humains ne peut être la seule solution face à ce constat et il devient incontournable de construire de nouveaux modèles organisationnels tout en visant une qualité de service permettant de répondre à 99% des appels entrants en moins de 60 secondes. Toutefois, ces modèles doivent prendre en compte la grande hétérogénéité des SAMU et de leur fonctionnement. A la lumière de ces constats, le travail de recherche présenté dans ce manuscrit a pour but d'évaluer l'efficacité organisationnelle et la résilience des SAMU dans la prise en charge des flux d'appels téléphoniques d'urgence pour faire face au quotidien et aux situations de crise. Cette évaluation nous permet de proposer et de tester de nouveaux schémas organisationnels afin de faire des préconisations adaptées aux particularités des centres d'appels d'urgence. Dans une première partie, nous proposons une méthodologie outillée pour le diagnostic et l'amélioration des centres d'appels d'urgence. Elle se décompose en deux grands volets : l'étude des données issues des centres d'appel d'urgence puis la conception et l'utilisation d'un double numérique. Pour chaque étape de cette méthodologie, nous proposons un outil associé. Dans une seconde partie, nous appliquons le premier volet de la méthodologie aux données de nos SAMU partenaires. Il s'agit d'être capable d'extraire de l'information et des connaissances des données de téléphonies ainsi que des processus métiers pour le traitement des appels d'urgence. La connaissance ainsi extraite permet de concevoir un double numérique qui soit proche du comportement réel des SAMU. Enfin dans une troisième partie, nous utilisons la matière produite précédemment pour modéliser et paramétrer un double numérique déployé sur un moteur de simulation à événements discret. Il nous permet de tester plusieurs scénarios en jouant sur différentes organisations de gestion de l'appel. Grâce à cela, nous faisons des préconisations sur les types d'organisations à adopter afin d'améliorer les performances des centres d'appel
BLPAD.Core: A Multi-Functions Optimizer Towards Daily Planning Generation in Home Health Care
No full textInternational audienceToday, a majority of the elderly want to live longer in autonomy and comfort. Since there is not enough space available in specialized institutions, Home Health Care Services (HHCS) constitute an important addition that reinforces the traditional system. With the increase in HHCS demands, the main challenge in this distributed system is the organization of care services in an HHC institution. This organizational problem is widely studied as a Home Health Care Scheduling and Routing Problem (HHCSRP) in the Operations Research (OR) community. Facing the diversity and complexity of demands, as done in OR, the formulated solution-oriented model aims at providing decision making support for the decision maker in HHC systems. This leads obstacles in the dataset / benchmark based experimental environment and critical analysis such as the degree of the optimality regarding generated solutions and the comprehensive visualization of solutions. In this paper, based on a systemic analysis of the existing benchmark and the solution approach for HHCSRP, a prototype named BLP AD. Core is introduced. It provides a full decision support system to the decision-maker in the HHC system. The functionality consists of an instance generation based on the real dataset, operational planning generation and solution visualization. This research highlights the scientific challenges and attempts to respond to the complicated expectations of HHC systems in a comprehensive manner
Toward Physical Internet-Enabled Supply Chain and Logistics Networks in Developing Countries
No full textPart 10: Collaboration in Supply ChainInternational audienceDeveloping countries have numerous challenges to manage in terms of supply chain and logistics networks such as safety, corruption, pollution, congestion, old and/or unsuitable vehicles, long lead times, economy, wastes and of course poor infrastructures and so on. While developed countries have started to change their mindset and toolboxes for managing their material flows all along their logistics networks, it is not yet the case for developing countries. This research work intends to study potentials benefit for these countries if there are drastic changes of the way physical of material flows are managed. In such a context, Physical Internet paradigm is considered as an interesting avenue for improvement. The objective of this paper is to draft an options that would be necessary to assess and to design the associated research methodology. Insights regarding an ongoing field-oriented research work in Cambodia are developed to highlight the potential
Evaluation of Microstructure and Hardness of Novel Al-Fe-Ni Alloys with High Thermal Stability for Laser Additive Manufacturing
No full textInternational audienceThe microstructure and phase composition of cast and laser-melted Al-Fe-Ni alloys were investigated. Two main phases—Al3(Ni,Fe) and Al9FeNi—were formed in the as-cast state. A fine microstructure without porosity or solidification cracks was observed in the Al-Fe-Ni alloys after laser treatment. The hardness of the laser-melted alloys was 2.5–3 times higher than the hardness of the as-cast alloys owing to the formation of an aluminum-based solid solution and fine eutectic particles. The formation of the primary Al9FeNi phase was suppressed as a result of the high cooling rate. Annealing these alloys at temperatures less than 300°C demonstrated the high thermal stability of the microstructure while maintaining the hardness. The Al-Fe-Ni alloys investigated in this study are promising heat-resistant materials for additive manufacturing because of their fine, stable structure, and the low interdiffusion coefficients of Fe and Ni