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This paper presents a new implementation method of the Extended-Oxley analytical model, previously proposed by Lalwani in 2009, for orthogonal cutting of metals with a Johnson–Cook thermo-elastoplastic flow law. The present work aims to improve the implementation of this analytical model in order to propose a unified solution that overcomes the main shortcomings of the original model: the non-uniqueness of the solution, the low accuracy of the obtained solution, and the relatively long computational time for a purely analytical approach. In the proposed implementation, the determination of the optimal set of model parameters is based on an optimization method using the Python LMFIT library with which we have developed a dual Levenberg–Marquardt optimization algorithm. In this paper, the performance and efficiency of the developed model are presented by comparing our results for a 1045 steel with the simulation results obtained in the original paper proposed by Lalwani. The comparison shows a considerable gain in terms of computational speed (more than 2000 times faster than the original model), uniqueness of the obtained solution, and accuracy of the obtained numerical solution (almost zero force imbalance).

The Selective Laser Melting (SLM) process has been progressively endorsed as an industrial manufacturing technique to produce high value-added components. However, one of the main obstacles to its wide application is the uncertainty regard- ing the successful completion of the manufacturing process. Mechanical stresses are generated and accumulated during the process, which may lead to the parts warping and cracking. Support structures may also detach from the part but it is not certain that these cracks conduct to the manufacturing failure. The process simulations currently available do not consider the cracking of the supports and the ongoing part’s deflection. The aim of this study is to investigate cone supports fracture behaviour comparing the results from a numerical model and the manufacturing of an industrial part. A model using 1D-beam elements to mesh the supports has been developed to consider the damage of the supports, their breakage and the ongoing deflection. Some numerical convergence issues are identified and solutions are proposed. Specific experimental set-ups are developed to characterise the behaviour of the supports individually and as a group. Significant improvements are denoted while injecting the measured characteristics within the model. Some key parameters of the supports damage behaviour are identified. It is shown that the supports mechanical characteristics are significantly different from the parts due to their manufacturing conditions and environment. Also, limitations regarding the characterisation of the supports as well as strong numerical convergence issues brought by multiple supports cracking are discussed.

High-pressure drops characteristic of microchannel heat sinks (MCHS) is an issue that needs to be addressed to reduce the size of heat-removing devices in compact electronic devices. Supercritical carbon dioxide (s-CO₂) is a suitable candidate being proposed as an alternative coolant to enhance the cooling of the microchannel heat sink (MCHS), with high heat flux, due to its favorable thermophysical properties near its critical point. In this study, numerical simulations are conducted to evaluate the thermal and hydraulic performance of a channel for a designed heat sink with s-CO₂ (at constant (Formula presented.)) and compare it with conventional liquid coolant (water). The effect of coolants mass flow rate ((Formula presented.)), channel aspect ratio (AR), and inlet temperatures on the thermal and hydraulic performance of one channel is studied by varying (Formula presented.) from 0.004 to 0.03 kg/s and AR from 0.33 to 10. The results show that, for the same aspect ratio, same geometry, and constant heat flux, s-CO₂ offers a higher overall heat transfer coefficient (32%) with a lower friction factor (pumping power) compared with the water at the same inlet temperature (T = 32°C). The results of pumping power comparison between two coolants reveal that for CO₂ in supercritical conditions ((Formula presented.), T = 32°C), the consumed power varies by change of the aspect ratio, which is 1.85 times lower than water for AR = 0.33 and is 3.6 times higher for AR = 10. However, in the subcooled state, the reverse effect of the aspect ratio is seen.

In the finite element simulation process, it is very common to use simplified models to replace the original complex models to reduce the computational cost. To improve the accuracy of simulation with simplified numerical models in Abaqus Explicit, we propose an inverse identification procedure to evaluate the equivalent loading conditions to be applied to these simplified models. We construct an objective function to test the correlation between the final deformed shape obtained by simulation on the full models and the simplified models. A Python identification program using the Levenberg–Marquardt algorithm is implemented to optimize this objective function. In parallel to this approach, we propose a data processing step, validated by a dynamic tensile test, to obtain more accurate numerical responses, including data extraction and estimation. Full numerical models for the Taylor test, dynamic tensile test, and dynamic shear test were constructed using Abaqus Explicit FEM code. The complete models were then replaced by simplified models, in which some non-essential parts were removed and some boundary conditions were modified. In order to obtain the same results in terms of the final geometry, the proposed inverse identification procedure is then used to calculate the equivalent impact velocities for the simplified models.

Non-linear numerical modeling is increasingly used for the simulation of complex processes such as forming or machining. The constitutive laws necessary for these simulations are therefore becoming more and more complex regarding the increasingly precise consideration of physical phenomena (plasticity, thermal dependence, damage ...) and their implementation in numerical codes requires the identification of many parameters. The use of these constitutive laws for dynamic or quasi-static applications requires the identification of these parameters under conditions close to those encountered during the real process, mainly in terms of deformation, strain rates, and temperatures. The availability of a constitutive law in the finite element codes does not guarantee the success of a study to be carried out if it does not comply with the model development criteria. This is because the models integrated in the numerical codes are not developed based on forms that are adjustable to any type of study. In this study, a new form of non-linear constitutive flow law based on the Modified Zerilli-Armstrong model, which can answer the above problem, has been developed to apply it to the numerical simulation of two different tests (a quasi-static compression test, the necking of a circular bar). This flow law is based on the modified Zerilli-Armstrong model, which, together with the new modified Johnson-Cook model, has been compared to appreciate the relevance of the proposal. For that, an implementation of this new law via the VUHARD subroutine into the Abaqus/Explicit finite element code was made to model the two tests. The comparison of the results obtained (from identification) by our proposed law with those obtained using the NMJC shows that this new law better approaches the experiments than the other one. This is also showed through the numerical results using the Abaqus software. It can be said that this way of formulating a flow law allows to highlight the great performance of the proposed approach. Although this law has been only used for quasi-static tests, we can say that it can also be used in dynamic tests.

International audience; In Engineer-To-Order (ETO) industrial contexts, decision-making about which systems to offer for sales or which subsystems to integrate into the systems for sales is based on various performance indicators. However, the lack of relevant information to evaluate these indicators challenges the decision-making process. In this article, to face this issue, a CBR approach is proposed for the evaluation of the performances of ETO systems. The main contributions are: (i) an object-oriented case representation model which allows to store previous evaluated systems for an effective and time efficient similar systems retrieval, and (ii) a method that allows to compute similarity between two systems that can have different structures.

Real-time management of hydraulic systems composed of multi-reservoir involves conflicting objectives. Its representation requires complex variables to consider all the systems dynamics. Interfacing simulation model with optimization algorithm permits to integrate flow routing into reservoir operation decisions and consists in solving separately hydraulic and operational constraints, but it requires that the water resource management model is based on an evolutionary algorithm. Considering channel routing in optimization algorithm can be done using conceptual models such as the Muskingum model. However, the structure of algorithms based on a network flow approach, inhibits the integration of the Muskingum model in the approach formulation. In this work, a flood routing model, corresponding to a singular form of the Muskingum model, constructed as a network flow is proposed, so that it can be easily integrated into the water management problem. A genetic algorithm is involved for the calibration of the model. The proposed flood routing model was applied on the standard Wilson test and on a 40 km reach of the Arrats river (southwest of France). The results were compared with the results of the Muskingum model. Finally, operational results for a water resource management system including this model are illustrated on a rainfall event.

International audience; This work deals with the simulation of complex manipulation tasks in virtual environments. Validating such complex tasks, possibly to be performed under strong geometric constraints, requires considering task and path planning jointly. The contribution of this work focuses on using task-related information at the path planning level. We propose an ontology-based approach to a) model the 3D environment where the simulated task is executed, based on an original multi-level environment model involving higher abstraction level data than the purely geometric models traditionally used, and b) automatically define path planning queries for the primitive ctions of a task plan, together with task-related geometric constraints on these queries. This approach allows the improvement of the state of the art from two points of view. First, our joint task and path planning approach allows the improvement of path planning through better semantic control of the path planning process. Second, if compared to hard-coded geometric constraints, the proposed ontology-based approach introduces a more flexible ay of defining geometric constraints through an inference process, and can be adapted to different applications of manipulation tasks.

International audience; Uncertainty analysis of hydrological models often requires a large number of model runs, which can be time consuming and computationally intensive. In order to reduce the number of runs required for uncertainty prediction, Bayesian networks (BNs) are used to graphically represent conditional probability dependence between the set of variables characterizing a flood event. Bayesian networks (BNs) are relevant due to their capacity to handle uncertainty, combine statistical data and expertise and introduce evidences in real-time flood forecasting. In the present study, a runoff–runoff model is considered. The discharge at a gauging station located is estimated at the outlet of a basin catchment based on discharge measurements at the gauging stations upstream. The BN model shows good performances in estimating the discharges at the basin outlet. Another application of the BN model is to be used as a reverse method. Knowing discharges values at the outlet of the basin, we can propagate back these values through the model to estimate discharges at upstream stations. This turns out to be a practical method to fill the missing data in streamflow records which are critical to the sustainable management of water and the development of hydrological models.

International audience; Validation and verification are the most important issues in railway applications due to cost and security reasons. Therefore, having a model of the system would be necessary in this case. Due to non-ideal test conditions in industrial applications, an accurate parameter identification process has to be defined. In this paper, bond graph method is used to model energy exchanges within components of a traction chain. More precisely, the non-linear transformer model and its parameter identification is studied. In the case of non-ideal test conditions, the usual Jiles-Atherton parameter identification procedure can not be performed. Regarding state of the art, the Jiles-Atherton parameter identification is discussed. It is highlighted that an uncomplete hysteresis cycle, including extremum point and coercive field are mandatory for an accurate parameter identification. The proposed identification process is applied to a real application case. The obtained parameters are then inserted into the overall system model. The consecutive simulations are compared to experimental data obtained through traction chain test bench.

There are many models of distributed computing, and no unifying mathematical framework for considering them all. One way to sidestep this issue is to start with simple communication and fault models, and use them as building blocks to derive the complex models studied in the field. We thus define operations like union, succession or repetition, which makes it easier to build complex models from simple ones while retaining expressivity. To formalize this approach, we abstract away the complex models and operations in the Heard-Of model. This model relies on (possibly asynchronous) rounds; sequence of digraphs, one for each round, capture which messages sent at a given round are received before the receiver goes to the next round. A set of sequences, called a heard-of predicate,defines the legal communication behaviors -- that is to say, a model of communication. Because the proposed operations behave well with this transformation of operational models into heard-of predicates, we can derive bounds, characterizations, and implementations of the heard-of predicates for the constructions., Full version of a paper accepted to FORTE 2020

There has been a tremendous increase in the production of ethylene over the last few decades, which has put tremendous focus on steam cracking processes and with an objective of improving its efficiency. This study, performed as a part of IMPROOF (Integrated guided Model PROcess Optimization of steam cracking Furnaces) project, is intended towards attaining that goal. Large Eddy Simulation (LES)- is at a stage of being mature enough to be used in design and optimization of processes in industrial equipments. However, the application of LES to study large flow equipments is still a technical challenge due to the high computational cost arising from numerical stiffness. In this study, a novel, chimera-based, local time stepping scheme is developed to speed up explicit time integration based LES solvers and applied (for the first time) to study the reactive flow inside a steam cracking furnace. This new numerical technique is studied for its numerical properties using Global Spectral Analysis (GSA) and the impact of local time stepping on the accuracy and resolution of the baseline numerical scheme is analyzed. The speed up obtained using this method is also ascertained with the help of canonical 2D and 3D nonreactive as well as reactive flow simulations. Numerical prediction of combustion inside a steam cracker comes with its own challenges. While detailed chemical mechanisms are ruled out from being used in simulations due to its high cost, simple global chemical mechanisms are not accurate enough to predict the flame structure and flame properties accurately. In this study, species transport equations are used with an analytically reduced chemical (ARC) mechanism. These chemical mechanisms are reduced from an up-to-date detailed mechanism using Directed Relational Graph with Error Propagation (DRGEP) technique and quasi-steady state (QSS) assumptions. The reduced mechanism is validated with respect to the detailed mechanism and experimental measurements is found to be in excellent agreement for all the flame properties of interest in this study. Radiative heat transfer is the predominant mode of heat transfer in steam cracking furnaces and hence cannot be avoided in realistic furnace simulations. In this study, the LES solver (along with the newly developed acceleration technique) is coupled with a radiative transfer equation (RTE) solver to carry out a coupled LES-RTE simulation. The approach is validated with experimental data from an axisymmetric jet diffusion flame and the experimental and numerical data is observed to be in good agreement with each other. Finally, all these methodologies are simultaneously applied to study the reactive flow occurring in the fire side of a steam cracking furnace. The LES acceleration technique speeds up the computations while ARC mechanism assists in predicting combustion reactions in an accurate manner. The radiative heat transfer effects are included by coupling the LES solver with the RTE solver as mentioned previously. Unsteady LES simulations of the combustion occurring inside the firebox is carried out. The computed and measured data for temperature and heat flux is found to be in close agreement with each other. LES of such a furnace demonstrates revealing information on the flame stabilization mechanism and the mean flame properties such as its shape and length and are discussed in this thesis. This study is intended to be a technology demonstrator by addressing three of the core challenges in the numerical modeling of steam cracking furnaces. By addressing these challenges, it is hoped that the petrochemical community is taking one step closer to using LES for their design and analysis processes in the near future.

This work deals with the customer-supplier relationship and concerns offer definition in Engineer-To-Order situations (ETO), by adopting the supplier point of view. In such cases, when the offer definition relies simply on key design choices without a detailed design, there is a specific risk (ETO-specific risk) that customer expectations cannot be fulfilled. This kind of risk is in addition to the conventional risks (non ETO-specific risk) involved in any delivery process (machine break down, resource not available, scrapped part…). In order to minimize the supplier risk of not being able to complete the offer as accepted and contracted by the customer, a knowledge-based system can be used to assist risk engineering. Consequently, this article proposes two interrelated knowledge modeling contributions. Firstly, a risk knowledge model which, when implemented in a knowledge-based system that supports risk characterization and risk treatment by using knowledge re-use techniques, is proposed and discussed. Secondly, two knowledge typologies for risk characterizations and treatments (both for ETO and non-ETO situations) in order to support risk knowledge, identification and modeling are also proposed and discussed. These contributions are innovative and groundbreaking in terms of both academics and applications: they provide a formal model to structure risk knowledge and a first list of risks and treatments to be taken into account in ETO and non ETO situations. After an introduction that presents the research gap, our objectives and an analysis of related works, our two contributions are described in two sections with respect to ISO31000 recommendations. The first section covers risk identification and evaluation while the second deals with risk treatments.

The mechanical model of a thin plate with boundary control and observation is presented as a port-Hamiltonian system (pHs), both in vectorial and tensorial forms: the Kirchhoff-Love model of a plate is described by using a Stokes-Dirac structure and this represents a novelty with respect to the existing literature. This formulation is carried out both in vectorial and tensorial forms. Thanks to tensorial calculus, this model is found to mimic the interconnection structure of its one-dimensional counterpart, i.e. the Euler-Bernoulli beam. The Partitioned Finite Element Method (PFEM) is then extended to obtain a suitable, i.e. structure-preserving, weak form. The discretization procedure, performed on the vectorial formulation, leads to a finite-dimensional port-Hamiltonian system. This part II of the companion paper extends part I, dedicated to the Mindlin model for thick plates. The thin plate model comes along with additional difficulties, because of the higher order of the differential operator under consideration., arXiv admin note: text overlap with arXiv:1809.11131

Les systèmes physiques sont par nature hétérogènes et multi-échelle. Cette présentation a pour but de montrer une méthodologie de modélisation générique basée sur les échanges de puissance qui s'applique sur grand nombre de systèmes physiques et surtout multi-physiques. Cette modélisation s'applique pour les systèmes d'échelles physiques et temporelles diverses. Enfin la méthodologie conduit à l'expressions d'équations du systèmes dont on pourra chercher à réduire la dimension afin d'accélérer les simulations numériques.

Reliability of electrical components is an issue studied to improve the quality of products, and to plan maintenance in case of failure. Reliability is measured by studying the causes of failure and the mean time to failure. One of the methods applied in this field is the study of component aging, because failure often occurs after degradation. The objective of this thesis is to model the degradation of components in electrical engineering, in order to estimate their lifetime. More specifically, this thesis will study large area organic white light sources (OLEDs). These sources offer several advantages in the world of lighting thanks to their thinness, their low energy consumption and their ability to adapt to a wide range of applications. The second components studied are electrical insulators applied to pairs of twisted copper wires, which are commonly used in low voltage electrical machines. First, the degradation and failure mechanisms of the various electrical components, including OLEDs and insulators, are studied. This is done to identify the operational stresses for including them in the aging model. After identifying the main causes of aging, general physical models are studied to quantify the effects of operational stresses. Empirical models are also presented when the physics of degradation is unknown or difficult to model. Next, methods for estimating the parameters of these models are presented, such as multilinear and nonlinear regression, as well as stochastic methods. Other methods based on artificial intelli­gence and online diagnosis are also presented, but they will not be studied in this thesis. These methods are applied to degradation data of organic LEDs and twisted pair insulators. For this purpose, accelerated and multifactor aging test benches are designed based on factorial experimental designs and response surface methods, in order to optimize the cost of the experiments. Then, a measurement protocol is described, in order to optimize the inspection time and to collect periodic data. Finally, estimation methods tackle unconstrained deterministic degradation models based on the measured data. The best empirical model of the degradation trajectory is then chosen based on model selection criteria. In a second step, the parameters of the degradation trajectories are modeled based on operational constraints. The parameters of the aging factors and their interactions are estimated by multilinear regression and according to different learning sets. The significance of the parameters is evaluated by statistical methods if possible. Finally, the lifetime of the experiments in the validation sets is predicted based on the parameters estimated by the different learning sets. The training set with the best lifetime prediction rate is considered the best.

The surface quality of the parts is one of the major objectives of the use of the high-speed milling (HSM). Tool path interpolations affect the machining operation of complex parts in HSM. In this paper, the influence of the different types of interpolation of the computer-aided manufacturing (CAM) on the surface roughness in the HSM machining of free forms is studied. To do this, a simulation tool of the surface texture for each type of interpolation is proposed. Then, experimental measurements expressing surfaces condition are carried out. To validate our approach, theoretical results with experimental ones are compared. As results, CAM interpolations of tool paths have demonstrated an important impact on the surface texture. In fact, a simulation prediction tool has confirmed the advantages of using polynomial interpolations in order to ameliorate the quality of the machined surface.

In this paper, we investigate the impact of environmental factors on the dynamical transmission of cholera within a human community. We propose a mathematical model for the dynamical transmission of cholera that incorporates the virulence of bacteria and the commensalism relationship between bacteria and the aquatic reservoirs on the persistence of the disease. We provide a theoretical study of the model. We derive the basic reproduction number R 0 which determines the extinction and the persistence of the infection. We show that the disease-free equilibrium is globally asymptotically stable whenever R 0 ≤ 1 , while when R 0 > 1 , the disease-free equilibrium is unstable and there exists a unique endemic equilibrium point which is locally asymptotically stable on a positively invariant region of the positive orthant. The sensitivity analysis of the model has been performed in order to determine the impact of related parameters on outbreak severity. Theoretical results are supported by numerical simulations, which further suggest the necessity to implement sanitation campaigns of aquatic environments by using suitable products against the bacteria during the periods of growth of aquatic reservoirs.

Incorporating touchscreen interaction into cockpit flight systems offers several potential advantages to aircraft manufacturers, airlines, and pilots. However, vibration and turbulence are challenges to reliable interaction. We examine the design space for braced touch interaction, which allows users to mechanically stabilise selections by bracing multiple fingers on the touchscreen before completing selection. Our goal is to enable fast and accurate target selection during high levels of vibration, without impeding interaction performance when vibration is absent. Three variant methods of braced touch are evaluated, using doubletap, dwell, or a force threshold in combination with heuristic selection criteria to discriminate intentional selection from concurrent braced contacts. We carried out an experiment to test the performance of these methods in both abstract selection tasks and more realistic flight tasks. The study results confirm that bracing improves performance during vibration, and show that doubletap was the best of the tested methods.

International audience; The impact behavior of innovative wood based sandwich structures with plywood core and skins made either of aluminum or of fiber reinforced polymer (carbon, glass, or flax composite skins) was investigated numerically. The wood based sandwich structures were subjected to low-velocity/low-energy impacts. An explicit nonlinear numerical model based on volume elements with a cohesive layer was developed. A plastic wood law already implemented in LS-DYNA was used in association with composite type damage criteria. Comparisons with experiments in terms of layer deformations and overall contact laws during impact showed satisfactory results.

International audience; In many design problems, the designer must select the design solution from among several alternative design solutions. In situations where relevant information to evaluate the design solutions are not available, the evaluation is imprecise and uncertain. Therefore, in order to make the right decision, it is necessary to take into account imprecision and uncertainty in the decision process. In this context, this article presents a multi-criteria decision support approach for the complete ranking of alternative design solutions. The proposed approach allows to take into account the imprecision and uncertainty related to the evaluation of the decision criteria. It is based on the possibility theory and PROMETHEE II ranking method. It is validated using an application dealing with the design of a technical bid solution (a couple of technical system and delivery process) during a bidding process.

Part 3: Task Modelling and Task-Based Approaches; International audience; Testing interactive systems is known to be a complex task that cannot be exhaustive. Indeed, the infinite number of combination of user input and the complexity of information presentation exceed the practical limits of exhaustive and analytical approach to testing [31]. Most interactive software testing techniques are produced by applying and tuning techniques from the field of software testing to try to address the specificities of interactive applications. When some elements cannot be taken into account by the software testing technique, they are usually ignored. In this paper we propose to follow an opposite approach, starting from a generic architecture for interactive systems (including both software and hardware elements) for identifying in a systematic way, testing problems and testing needs. This architecture-driven approach makes it possible to identify how software testing knowledge and techniques can support interactive systems testing but also where the interactive systems engineering community should invest in order to test their idiosyncrasies too.

International audience; During the development of a complex system, data models are the key to a successful engineering process, as they contain and organize all the information manipulated by the different functions involved in the design of the system. Moreover, these data models evolve throughout the design, as the development raises issues that have to be solved through a restructuration of data organization. But any such data model evolution has a deep impact on the functions that have already being defined.Recent research tries to deal with this issue by studying how complex industrial data models evolve from one version to another and how their data instances co-evolve. Complexity and scalability issues make this problem a major scientific challenge, leading to huge gains in development efficiency. This problem is of particular interest in the field of aeronautics and space systems. Indeed, the development of these systems produces many complex data models associated to the designed systems and/or to the systems under design, hence on the one hand data models are available. On the other hand, it is well known that these systems are developed in the context of collaborative projects that may last for decades. In such projects, specifications together with the associated data models are bound to evolve and engineering processes shall take into account this evolution.Our work addresses the problem of data model evolution in a model-driven engineering setting. We focus on minimizing the impact of model evolution on the system development processes in the specific context on the space engineering area, where data models may involve thousands of concepts and relationships, and we investigate the performance of the model-based development (MBD) approach we propose for data model evolution over two space missions, namely PHARAO and MICROSCOPE.

When modelling a cutting operation, the constitutive model of the machined material is one of the key parameters to obtain accurate and realistic results. Up to now, the Johnson-Cook model is still the most used, even if an increasing number of models, such as the Hyperbolic TANgent (TANH) model, were introduced last years to overcome its limitations and come closer to the actual material behaviour. Experimental tests on dedicated equipment are usually required to identify the parameters of the constitutive models. This paper introduces the Coupled Eulerian-Lagrangian (CEL) formalism to model in 3D the Taylor impact test, one of the common tests to perform that parameters identification. Indeed, one identification way involves modelling the test to determine the constitutive model parameters by comparing the experimental and the numerical samples geometries. The developed CEL model is validated against a Lagrangian reference model for a steel alloy and the Johnson-Cook constitutive model. The main goal of using the CEL method is to get rid of the elements distortion due to the high strains and strain rates during the test. Mesh dependence of the results is highlighted and a recommendation is provided on the mesh to adopt for future work. The CEL model of the 3D Taylor impact test is then extended to the use of the TANH model. The results are finally compared with that of the Johnson-Cook constitutive model.

Our thesis work focuses on the proposal of a modeling and simulation (M&S) framework for urban transportation systems. A transportation system is a complex system generally made up of several autonomous subsystems, which behavior can be expressed through several levels of abstraction. The study of such a system requires the use of M&S for a better understanding of its complexity.We adopt the Multi-Perspective Modeling and Holistic Simulation (MPM&HS) approach to M&S of urban transportation systems, in order to better take into account all required levels of abstraction. The MPM&HS approach, which has been introduced in recent research works, is a complex systems analysis methodology that consists in building distinct models of the same system from various relevant perspectives and then integrating them together for a better understanding of the system’s complexity. It has successfully applied to healthcare systems and has shown promising results.Our MPM&HS-structured M&S framework is based on an ontology of the domain of urban transport systems, which capitalize on existing conventional models. We use the SES/MB (System Entity Structure/Model Base) formalism to specify this ontology, and the HiLLS (High Level Language for System Specification) formalism to specify the conventional models. While SES/MB is a well-established ontological formalism that has been defined within the DEVS (Discrete Event System Specification) theory, HiLLS is a visual formalism that has been created to simplify the specification of DEVS simulation models and, which thus facilitates discussion with experts in the domain of urban transportation systems when specifying simulation models.In the last part of the work, we propose a complete application of our framework on a case study of urban traffic M&S within a localized area of the city of Bamako, in Mali., Notre travail de thèse porte sur la proposition d’un cadre de modélisation et simulation (M&S) des systèmes de transport urbain. Un système de transport urbain est un système complexe généralement constitué de plusieurs sous-systèmes autonomes et dont le fonctionnement peut s’exprimer à travers plusieurs niveaux d’abstraction. L’étude d’un tel système nécessite l’usage de la M&S pour une meilleure appréhension de cette complexité.Nous adoptons, dans la M&S des systèmes de transport urbain, l’approche de modélisation multi-perspective et de simulation holistique (Multi-Perspective Modeling and Holistic Simulation, MPM&HS) afin de mieux prendre en compte les différents niveaux d’abstraction dans ces systèmes. L’approche MPM&HS, qui a été définie dans des travaux récents, est une démarche méthodologique d’analyse des systèmes complexes qui consiste à construire des modèles distincts selon différentes perspectives d’un système complexe et à les intégrer ensemble pour une meilleure compréhension de sa complexité. Elle a été mise en œuvre dans le cas des systèmes de santé et a donné des résultats prometteurs.L’application de l’approche MPM&HS permet de structurer notre cadre de M&S basé sur une ontologie du domaine des systèmes de transport urbain qui capitalise sur les modèles conventionnels existants dans ce domaine. Nous utilisons le formalisme SES/MB (System Entity Structure/Model Base) pour spécifier cette ontologie, et le formalisme HiLLS (High Level Language for System Specification) pour spécifier les modèles conventionnels. SES/MB est un formalisme d’ontologie connu et bien établi, qui a été créé dans la cadre de la théorie DEVS (Discrete Event System Specification). HiLLS, lui, est un formalisme visuel créé pour simplifier la spécification des modèles de simulation DEVS et permet ainsi de faciliter l’échange avec les experts du domaine des systèmes de transport urbain lors de la spécification des modèles de simulation.Nous proposons dans la dernière partie du travail une mise en œuvre de notre cadre sur une étude de cas de trafic urbain dans un secteur localisé de la ville de Bamako, au Mali.

The computer science research team at our university works in modelling and simulation to studycomplex natural systems in a holistic way.In this work, we have set ourselves the goal of using computer simulation as a virtual laboratory todesign a decision support tool in a multidisciplinary context.The focus of our work is to propose a generic executable model to allow decision support and to useit towards the modelling of a fishery system. We propose to apply our work to the management offish stocks in Corsica.This led us to the following approach: the first step is the representation of the complex system.For this we have looked for a paradigm to represent components within a hierarchical structurecapable of interactions and autonomous decision making.The agent paradigm lends itself very well to the representation of complex bio-economic systems.Then, the question of the robustness of the approach arose. For this purpose, we used the theory ofmodeling and simulation (TM\&S) proposed by B.P. Zeigler. In our case, the PDEVS formalism canbe considered as a unifying and pivotal formalism. It allows the inclusion of other concepts, we speakof multi-modeling.We complement it with the agent paradigm in order to benefit from itsexpressiveness and its ability to describe entities (the agents) simply, their mutual interactions, andthe environment in which they evolve. Finally, in order to respect a formal framework, essential to thepreliminary work of conceptualization, we use the DPDEMAS formalization proposed by R.Franceschini and already developed in our team. This formalization offers in its original form aninteresting analogy between a Multi-Agent System (MAS) and the PDEVS and DSDE models(dynamic version of PDEVS). We find a description of the agent from a body which models itsphysical representation in an environment, as well as from a mind which is the place of decisionmaking.This led us to consider the problem of decision making. The central issue was therefore to proposean executable model that is sufficiently generic to allow decision support and to use it in the case ofmodeling a fishery. To do so, we propose an approach that provides agents with bricks inspired bySoar. An optimization brick allowing to refine the agents' decisions. A reinforcement learning brickallowing agents to develop their knowledge in a given situation.We complete this description with a first didactic example before applying our approach to twoexamples of modeling a fishery system based on 50 years of data.The first example is a 5-component model to simulate scenarios with quotas.The second example is a 6-component model to simulate scenarios with quotas, and additionallytaking into account space and migrations between areas. Nevertheless, these two models only aimat validating our approach. Indeed, if thanks to these two examples, we obtain coherent resultsallowing us to validate their behaviour, these models are purely theoretical and do not represent thereality of the system sufficiently well to be used to assist in the management of fishery resources.The perspectives that we envisage in the future are on the one hand the integration of new learningand decision methods, to develop a fishery model more representative of the reality or to use ourapproach to treat other case studies., L'équipe de recherche informatique de notre université travaille en modélisation et en simulation afin d'étudier de manière holistique les systèmes naturels complexes.Dans ce travail, nous nous sommes fixés comme objectif d'utiliser la simulation informatique comme éprouvette virtuelle afin de concevoir un outil d'aide à la décision dans un contexte pluridisciplinaire.L'enjeu central de notre travail est de proposer un modèle exécutable suffisamment générique pour permettre l'aide à la décision et de l'utiliser dans le cas de la modélisation d'une pêcherie. Nous proposons d'appliquer nos travaux à la gestion des stocks de poissons en Corse.Ceci nous a conduits à suivre la démarche suivante : la première étape est la représentation du système complexe. Pour cela nous avons cherché un paradigme pour représenter des composants à structure hiérarchique capables d’interactions et d'autonomie de décision. Le paradigme agent se prête très bien à la représentation de systèmes complexes bio-économiques.Ensuite, la question de la robustesse de l’approche s’est posée. Pour cela nous nous sommes rapprochés de la théorie de la modélisation et de la simulation (TM\&S) proposée par B.P. Zeigler. Dans notre cas, le formalisme PDEVS peut être considéré comme un formalisme unificateur et pivot.En effet, celui-ci permet d'inclure d'autres concepts, on parle de multi-modélisation. Nous le complétons notamment avec le paradigme agent afin de bénéficier de son expressivité et de sa faculté à décrire simplement des entités (les agents), leurs interactions mutuelles, ainsi l'environnement dans lequel elles évoluent. Enfin, pour respecter un cadre formel, indispensable au travail préalable de conceptualisation, nous utilisons la formalisation DPDEMAS proposée R.Franceschini et déjà développé dans notre équipe. En effet, cette formalisation offre dans sa forme originale une analogie intéressante entre un Système Multi-Agents (SMA) et les modèles PDEVS etDSDE (version dynamique de PDEVS). Nous y retrouvons une description de l'agent à partir d'un corps qui modélise sa représentation physique dans un environnement, ainsi qu'à partir d'un esprit qui est le lieu des prises de décision.Ceci nous a amené à nous pencher sur la problématique de la prise de décision. L'enjeu central était donc de proposer un modèle exécutable suffisamment générique pour permettre l'aide à la décision et de l'utiliser dans le cas de la modélisation d'une pêcherie. Pour cela, nous proposons une approche mettant à disposition des agents des briques inspirées de Soar. Une brique d’optimisation permettant d’affiner les décisions des agents. Une brique d'apprentissage par renforcement permettant aux agents de compléter leurs connaissances dans une situation donnée.Nous complétons cette description par un premier exemple didactique avant d’appliquer notre approche à deux exemples de modélisation d’un système de pêcherie basé sur 50 ans de données.Le premier exemple est un modèle à 5 composants pour simuler des scénarios avec quotas.Le second exemple est un modèle à 6 composants pour simuler lui aussi des scénarios avec quotas,avec en plus la prise en compte de l'espace et des migrations entre zones. Néanmoins, ces deux modèles, n'ont pour objectif que de valider notre approche. En effet, si grâce à ces deux exemples,nous obtenons des résultats cohérents nous permettant de valider leur comportement, ces modèles sont purement théoriques et ne représentent pas suffisamment bien la réalité du système pour pouvoir être utilisés en l'état pour aider à la gestion des ressources halieutiques.Les perspectives que nous envisageons par la suite sont d’une part l’intégration de nouvelles méthodes d’apprentissage et de décision, et d’autre part de développer un modèle de pêcherie plus représentatif de la réalité ou encore d’utiliser notre approche pour traiter d’autres cas d’études.

International audience; Successful 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.

International audience; In order to face an increasing economic competition, industrial manufacturers wish to reduce the time and cost of product development. Furthermore, up-to-date products are more and more integrated, and must be assembled, disassembled or maintained under potentially very strong geometric constraints. In the context of Industry 4.0, manufacturers are therefore expressing the desire to validate all the tasks related to their products lifecycles, from design stage on, by simulation using a digital mock-up, and before building the physical prototypes. A key issue is then to find a trajectory, a movement, to show the feasibility of the simulated scenarios. Automatic path planning algorithms, developed by the robotics community from the 1980s on, have been widely used for this purpose. In this paper, we intend to improve the relevance of the trajectories proposed by such algorithms and the associated computation times. To do so, we consider: a) the use of path planning algorithms or of combinations of these; b) the involvement for the environment modelling of data with a higher abstraction level than the purely geometric data traditionally used; and c) the representation of the knowledgerelated to the task to be performed by using ontologies. The approaches developed and associated improvements of the state of the art are validated experimentally through the simulation of highly geometrically constrained manipulation tasks.

In this research work, silica monoliths with high porosity (83 %), double pore size distribution (20 μm and 20 nm macro- and mesopores diameters, respectively) and high surface area (370 m2 g-1) have been used as solid supports to immobilize a laccase from Trametes versicolor by covalent grafting with glutaraldehyde. Enzymatic monoliths were applied to degrade tetracycline (TC) in aqueous solutions in a tubular “Flow Through Reactor” configuration with recycling. During the first 5h of reaction at pH 7, 40–50% of TC was degraded, and then a threshold was reached. One of the hypotheses explaining this behaviour is a possible co-substrate lack (oxygen) near catalytic sites. Enzymatic monoliths were used during 75 h of sequential operation without losing activity. A mathematical model built coupling the Michaelis-Menten reaction kinetics with a dynamic mass balance allowed computing TC degradation efficiency. Simulation results revealed that the global process is controlled by the enzymatic kinetics but the monolith size could be adapted to degrade 100 % TC in a single pass., Dans ce travail de recherche, des monolithes en silice présentant une très grande porosité (83 %), une double distribution de taille de pores (des macropores de diamètre 20 μm et des méseopores de diamètre 20 nm) et une très grande surface spécifique (370 m2 g-1) ont été utilisés comme supports pour immobiliser une laccase de Trametes versicolor par greffage covalent avec du glutaraldéhyde. Les monolithes enzymatiques ont été utilisés pour dégrader la tétracycline (TC) en solution aqueuse dans un réacteur de configuration tubulaire type "Flow Through Reactor" avec recyclage. Au cours des 5 premières heures de réaction à pH 7 ; 40 à 50 % de la TC a été dégradée, puis un seuil a été atteint. Une des hypothèses pouvant expliquer ce comportement est un éventuel manque de co-substrat (oxygène) à proximité des sites catalytiques. Des monolithes enzymatiques ont été utilisés pendant 75 h de fonctionnement séquentiel sans perte d'activité. L'efficacité de la dégradation de la TC a pu être simulée à travers un modèle mathématique construit en couplant la cinétique de la réaction (Michaelis-Menten) avec un bilan matière en régime dynamique. Les résultats de la simulation ont révélé que le procédé global est contrôlé par la cinétique enzymatique mais que la taille des monolithes pouvait être adaptée pour dégrader 100 % de la CT en un seul passage à travers un monolithe.

Oxide dispersion strengthened (ODS) ferritic-martensitic steels are advanced high-performance structural materials for next generation nuclear and fusion facilities. An important issue for operation performance of these steels is their resistance to detrimental effects of transmutation gases, helium and hydrogen, with a particular attention to the effects from dense population of nano-size oxide particles. The objective of the thesis is a systematic investigation of fundamental trends in gas-driven microstructure development in ferritic-martensitic ODS steels in reply to variations in the accumulated gas content, gas accumulation and damage rates, and temperature, with particular attention to the role of oxide particles. The applied experimental approach involved saturation of steel samples with various amounts of helium and hydrogen atoms using ion implantation at the JANNuS-Orsay facility in well-controlled conditions. The reference material used was ODS-EUROFER steel. The microstructural changes accompanying gas accumulation were revealed using transmission electron microscopy (TEM). For the better understanding of the mechanisms of helium interaction with oxide particles, the experiments were backed up with ion implantation into a model Y₂O₃/FeCr bilayer system and with relevant analytical and numerical modeling. Microstructural investigations of ODS-EUROFER samples implanted to high He fluences reveal a persistent partitioning of introduced gas between different microstructural features. In addition to gas bubbles in the grain bulk, extensive bubble precipitation on extended defects (grain boundaries and dislocations) and precipitates (carbides and oxides) was observed. The relative abundance of bubbles associated with different microstructural features is found to be sensitive to implantation conditions and changes in uncorrelated manner with the variation of implantation parameters. Overall, the main contributions to steel volume expansion (swelling) and the He inventory were from bubbles on grain boundaries and, at lower implantation temperatures and higher fluxes, from bubbles in the grain matrix. However, the preferential He accumulation at grain boundaries does not lead to bubble coalescence and growth of huge grain boundary cavities, without causing high-temperature helium embrittlement. Oxide nanoparticles were found to be efficient centers for helium bubble nucleation, each hosting a single bubble typically noticeably larger than bubbles in other populations. However, their contributions to both swelling and He inventory were estimated to be generally relatively minor as compared to other bubble populations, implying that oxide particle provide no substantial improvement of steel radiation performance. On the contrary, the large bubbles bear the risk of accelerated bubble-to void transition in unfavorable conditions, launching uncontrolled void swelling. The viability of such effect was demonstrated in experiments on simultaneous steel implantation with He and Au ions and quantified using analytical modeling. Under sequential helium and hydrogen implantation into ODS-EUROFER steel, notable increase of hydrogen uptake was observed as compared to oxide-free steel. However, the parameters of He bubble microstructure and, hence, the overall steel radiation resistance were found to be only weakly influenced by hydrogen, in both ODS-EUROFER steel and in Y₂O₃/FeCr bilayer system. Visible hydrogen effects on bubble microstructure were minor and manifested only after the room temperature H implantation. Summing up, ODS steel is shown to be resistant to void swelling up to very high levels of accumulated helium and hydrogen. The presence of high density of nano-oxides is generally beneficial for steel radiation tolerance, but their influence is not as strong as commonly expected. Hydrogen trapping in helium bubbles doesn’t manifest any potential risks for ODS steel radiation tolerance under experimental conditions studied., Les aciers ferritiques-martensitiques renforcés par dispersion d'oxydes (ODS) sont des matériaux de structure de haute performance pour les futures installations nucléaires de fission et de fusion. Un problème important pour la performance de ces aciers sous irradiation est leur résistance aux effets néfastes des gaz de transmutation, l'hélium et l'hydrogène, avec une attention particulière aux effets liés à la forte densité de nanoparticules d'oxyde. L'objectif de la thèse est une étude systématique et fondamentale de l’évolution de la microstructure induite par les gaz légers dans les aciers ODS ferritiques-martensitiques en fonction de la teneur en gaz accumulée, du taux d'endommagement et de la température, en accordant une attention particulière au rôle des nanoparticules d'oxyde. L'approche expérimentale utilisée a consisté à saturer des échantillons avec différentes quantités d'hélium et d'hydrogène, par implantation ionique à JANNuS-Orsay, dans des conditions bien contrôlées. Le matériau de référence utilisé était l'acier ODS-EUROFER. Les modifications microstructurales accompagnant l'accumulation de gaz ont été révélées par microscopie électronique à transmission. Pour une meilleure compréhension des mécanismes d’interaction de l’hélium avec les nanoparticules d’oxyde, les expériences ont été complétées par des implantations ioniques dans un système modèle de couches minces Y₂O₃/FeCr, et par une modélisation analytique et numérique pertinente. Cependant, leurs contributions au gonflement sont généralement relativement mineures par rapport aux autres populations de bulles. Au contraire, les grosses bulles comportent le risque d'une transition accélérée d’une bulle à une cavité dans des conditions défavorables, ce qui provoque un gonflement non contrôlé des cavités. La viabilité d'un tel effet a été démontrée dans des expériences d'implantation d’ions He et d’irradiation d’ions Au simultanées, et quantifiée à l'aide d'une modélisation analytique. Lors de l'implantation séquentielle d'hélium et d'hydrogène dans l'acier ODS-EUROFER, une augmentation notable de l'absorption d'hydrogène a été observée par rapport à l'acier ne contenant pas d’oxyde. Cependant, la résistance globale à l’irradiation de l'acier n'a été que faiblement influencée par l'hydrogène, aussi bien dans l'acier ODS-EUROFER que dans le système modèle Y₂O₃/FeCr. Les effets visibles de l'hydrogène sur la microstructure des bulles étaient mineurs et ne se manifestaient qu'après l'implantation d’H à température ambiante. En résumé, l’acier ODS s’avère résistant au gonflement jusqu’à des niveaux très élevés d’hélium et d’hydrogène accumulés. La présence de nano-oxydes à haute densité est généralement bénéfique pour la tolérance à l’irradiation de l'acier, mais leur influence n'est pas aussi forte que celle attendue. Le piégeage de l’hydrogène dans les bulles d’hélium ne présente aucun risque potentiel pour la tolérance à l’irradiation de l’acier ODS dans les conditions expérimentales étudiées.

International audience; We propose the modeling of hysteresis nonlinearities in a piezoelectric material-based tube actuator classically employed in precise positioning applications under different sur-rounding temperatures. Beyond the voltage-to-displacement hysteresis nonlinearities they exhibit, these actuators are sensitive to the surrounding temperature. Therefore, contrary to the existing works in the literature where the two phenomena were treated individually,this paper suggests to model the hysteresis nonlinearities and the temperature effects si-multaneously. First an experimental study was performed to investigate the effects of the surrounding temperature on the voltage-to-displacement hysteresis loops of the piezoelectric tube actuators. The experimental results show that increasing the input surrounding temperature contributes an increase in the voltage-to-displacement sensitivity of the piezoelectric tube actuator under the input voltage range considered in the experimental tests. Then, two different nonlinear temperature-dependent hysteresis models a temperature-dependent (TD) electromechanical model and a temperature-dependent Prandtl-Ishlinskii model (TD-PI) were proposed to account the temperature effects on the hysteresis nonlinearity. In first, the mathematical formulation of TD-electromechanical model was presented to describe the electrical and mechanical properties of piezoelectric tube actuator. This model integrates the temperature dependent electromechanical coupling factor to model the temperature effects, the Simscape library in MATLAB-Simulink software was used to develop a physical simulation for the TD-electromechanical model. In a second time, a TD-PI model was proposed to describe the voltage-to-displacement characteristic of piezoelectric tube actuator using a proposed temperature shape function. The parameters of the two proposed models were estimated using proposed optimization algorithms based on Grey Wolf Optimizer (GWO). The modeling results demonstrate that the two proposed models can account for the hysteresis nonlinearities of the piezoelectric tube actuators under different levels of the surrounding temperatures. Finally, the analytical inverse of TD-PI model was derived and applied in feed forward manner to compensate the hysteresis nonlinearities under different levels of the surrounding temperatures.

The export of riverine dissolved organic carbon (DOC) to the oceans is determinant in carbon exchanges of the estuaries and oceanic food webs. Past research returned a global DOC export around 160–450 TgC.yr−1 by using complex process-based models or yearly average estimates that could have been misjudged. In this study, we try to understand the complex processes explaining daily DOC exports among 341 exoreic watersheds covering 71% of freshwater flows to the oceans. Based on a dataset of DOC concentrations among rivers at the global scale, we were able to link DOC concentrations to daily discharge, the ration between the soil organic carbon content and the amount of precipitations and the average air temperature in the watersheds. We have found a global riverine DOC flux of 131.6 TgC.yr−1 based on daily data and a generic model. Tropical and cold watersheds are the main contributors with 49.5% and 33.3% of the global riverine DOC flux on the two last decades while temperate, semi-arid and polar basins represent 15.9%, 0.7% and 0.6%, respectively. Temporal exports range from 0.1 to 0.16 TgC.day−1 in tropical areas, 0.03–0.32 TgC.day−1 in cold areas and 0.03–0.08 TgC.day−1 in temperate areas. Atlantic and Arctic oceans receive the most important fluxes (0.12–0.2 and 0.01–0.26 TgC.day−1). In a climate change context, this generic equation could be introduced in hydrological modelling tools to predict future DOC fluxes trends.

Post-combustion CO2 capture in a hollow fiber membrane contactor (HFMC), using imidazolium-based room temperature ionic liquids (RTILs) and amino acid ionic liquids (AAILs) as absorbents, was studied through an experimental and modeling approach. Equilibrium solubility of CO2 in RTILs was measured by isochoric pressure drop. Pore wetting was analyzed by measuring surface tension of the RTILs, contact angle and liquid entry pressure (LEP). The experimental work of CO2 capture from a gas mixture was carried out with a laboratory scale unit using a single HFMC for absorption or two coupled HFMCs one for absorption and a second for desorption working simultaneously. Furthermore, robust and rigorous dynamic modelling approaches were developed for isothermal (with RTILs) and non-isothermal (with AAILs) absorption. Both isothermal and non-isothermal models were validated with experimental data and were used to simulate a large range of operating conditions. Initial high values of CO2 absorption rate and experimental mass transfer coefficients decreased with operation time and reached a nearly constant value at pseudo-steady-state. Before reaching pseudo-steady-state, the separation efficiency of coupled process was higher when compared with the absorption with a single module.; Des contacteurs membranaires à fibres creuses (HFMC) ont été utilisés pour la capture du CO2 des courants gazeux. Pour ce faire, des liquides ioniques à température ambiante (RTIL) et des liquides ioniques d'acides aminés (AAIL) à base d'imidazolium ont été utilisés comme absorbants, avec une double approche expérimentale et de modélisation. La solubilité du CO2 à l'équilibre dans les RTIL a été mesurée par la chute de pression isochronique. Le mouillage des pores a été analysé avec la mesure de la tension superficielle des RTIL, l'angle de contact et la pression d'intrusion (LEP). Le travail expérimental de capture du CO2 à partir d'un mélange gazeux a été réalisé avec une unité à l'échelle de laboratoire en utilisant soit un HFMC pour l'absorption simple soit deux HFMC couplés, travaillant simultanément un en absorption et le second en désorption. En outre, une approche de modélisation en régime dynamique robuste et rigoureuse a été développée pour l'absorption isotherme (avec des RTIL) et non isotherme (avec des AAIL), les modèles développés ont étés validés avec les résultats expérimentaux et utilisés pour simuler un large éventail des conditions opératoires. Le flux d'absorption du CO2 et les coefficients de transfert de masse expérimentaux, initialement très élevés, décroisent avec le temps atteignant une valeur presque constante arrivant à un état pseudo-stationnaire. Avant d'atteindre l’état pseudo-stationnaire, le rendement de séparation du procédé couplé s’est montré plus efficace que l’absorption avec un module unique.

Post-combustion CO2 capture in a hollow fiber membrane contactor (HFMC), using imidazolium-based room temperature ionic liquids (RTILs) and amino acid ionic liquids (AAILs) as absorbents, was studied through an experimental and modeling approach. Equilibrium solubility of CO2 in RTILs was measured by isochoric pressure drop. Pore wetting was analyzed by measuring surface tension of the RTILs, contact angle and liquid entry pressure (LEP). The experimental work of CO2 capture from a gas mixture was carried out with a laboratory scale unit using a single HFMC for absorption or two coupled HFMCs one for absorption and a second for desorption working simultaneously. Furthermore, robust and rigorous dynamic modelling approaches were developed for isothermal (with RTILs) and non-isothermal (with AAILs) absorption. Both isothermal and non-isothermal models were validated with experimental data and were used to simulate a large range of operating conditions. Initial high values of CO2 absorption rate and experimental mass transfer coefficients decreased with operation time and reached a nearly constant value at pseudo-steady-state. Before reaching pseudo-steady-state, the separation efficiency of coupled process was higher when compared with the absorption with a single module.; Des contacteurs membranaires à fibres creuses (HFMC) ont été utilisés pour la capture du CO2 des courants gazeux. Pour ce faire, des liquides ioniques à température ambiante (RTIL) et des liquides ioniques d'acides aminés (AAIL) à base d'imidazolium ont été utilisés comme absorbants, avec une double approche expérimentale et de modélisation. La solubilité du CO2 à l'équilibre dans les RTIL a été mesurée par la chute de pression isochronique. Le mouillage des pores a été analysé avec la mesure de la tension superficielle des RTIL, l'angle de contact et la pression d'intrusion (LEP). Le travail expérimental de capture du CO2 à partir d'un mélange gazeux a été réalisé avec une unité à l'échelle de laboratoire en utilisant soit un HFMC pour l'absorption simple soit deux HFMC couplés, travaillant simultanément un en absorption et le second en désorption. En outre, une approche de modélisation en régime dynamique robuste et rigoureuse a été développée pour l'absorption isotherme (avec des RTIL) et non isotherme (avec des AAIL), les modèles développés ont étés validés avec les résultats expérimentaux et utilisés pour simuler un large éventail des conditions opératoires. Le flux d'absorption du CO2 et les coefficients de transfert de masse expérimentaux, initialement très élevés, décroisent avec le temps atteignant une valeur presque constante arrivant à un état pseudo-stationnaire. Avant d'atteindre l’état pseudo-stationnaire, le rendement de séparation du procédé couplé s’est montré plus efficace que l’absorption avec un module unique.

The use of titanium alloys has become more widespread in recent years. Regardless, although research work is enhancing, productivity levels remain low. Several alternatives have been considered and one of the techniques is envisaged is heating assistance. The objective is then to increase the temperature locally in order to benefit from thermal softening. However, the research is based on power-controlled laser assistance where the temperature levels are not considered. For this purpose, this article suggests a study based on a new experimental device which allows to control the temperature of the machined part. After presenting the device and the material used (Ti5553), the study first shows the effect of temperature on cutting forces. Three temperature ranges and three trends are shown. A first where temperature has no effect, a second when there is a substantial gain and a third where temperature has a real impact. In order to understand the existing links, two methods were used. A finite element model integrating a new law of behaviour was developed and shows the very high temperature levels reached in the cutting areas. Then, to better understand the phenomena governing cutting, we looked at chip formation and the link between chip formation, temperature and its effect on the microstructure. After all, an economic analysis completes this article and highlights the small gains of this assistance.

International audience; Through the diversity of criteria and stakes, the uncertain nature of the entailed phenomena and the multi-scale aspects to be taken into account, a river restoration project can be considered as a complex problem. Integrative approaches and modelling tools are thus needed to help river managers make predictions on the evolution of hydromorphological, socio-economic, safety and ecological issues. Such approach can provide valuable information for handling long-term management plans that consider the interaction and the balance of stakeholders interests and river system functioning. In this paper, we present a probabilistic participatory modelling (PM) method that assesses the effects of given restoration actions, knowing the hydromorphological modifications that they may induce on the safety, ecological and socio-economic aspects with the help of local stakeholders through several workshops. To support this strategy, we used Bayesian networks (BNs) as modelling tools as their causal graphs can combine multidimensional knowledge and data from diverse natures. We introduce the causal graphs elaborated with the help of the stakeholders and convert it into BNs that can assist restoration decisions by considering the available decision and utility functions to provide guidance to decision-makers. This was applied to the “Lac des Gaves” reach in the Hautes-Pyrénées, France, a reach that has gone through severe sediment extractions for over 50 years. Each network represents possible restoration decisions linked to one of the observed issues. The paper demonstrates how BNs used as a decision support system (DSS) can help to assess the influence of given management strategies on the river system with the consideration of stakeholders’ knowledge and integration in all the modelling process.

International audience; This paper considers the problem of modeling the mechanism of inoperability propagation within a network of complex systems (a production unit, a transportation system, an energy supply system, etc.). We are particularly interested in modeling one of the main attributes of complexity that is interaction; indeed, interactions between systems in a network or components in a system have the effect of propagating and perhaps even amplifying local inoperabilities. Two types of interactions are considered: influence that can be described by an acyclic hierarchical relationships graph of the interacting systems or components and interdependence for which the graphical representation of relationships allows loops. Hierarchy is mainly functional or structural and is analyzed and established in this communication using fault tree analysis (FTA) as the underlying mathematical tools whereas interdependence is apprehended through dynamic Bayesian network (DBN) by considering that effects are delayed. The ultimate DBN model (obtained in two steps: (1) a static Bayesian network (BN) isomorphic to the FTA model and then (2) DBN model by introducing delayed interdependence effects) of a complex system can serve as a decision support system for many risk related scenarios analysis and/or activities such as predictive maintenance.

International audience; Motivated by the design and optimization of the water exchange networks in Eco-Industrial Parks (EIP), we investigate the abstract Blind-Input model for general exchange networks. This abstract model is based on a Game Theory approach, formulating it as a Single-Leader-Multi-Follower (SLMF) game: at the upper level, there is an authority (leader) that aims to minimize the consumption of natural resources, while, at the lower level, agents (followers) try to minimize their operating costs. We introduce the notion of Blind-Input contract, which is an economic contract between the authority and the agents in order to ensure the participation of the latter ones in the exchange networks. More precisely, when participating in the exchange network, each agent accepts to have a blind input in the sense that she controls only her output fluxes, and the authority commits to guarantee a minimal relative improvement in comparison with the agent’s stand-alone operation. The SLMF game is equivalently transformed into a single mixed-integer optimization problem. Thanks to this reformulation, examples of EIP of realistic size are then studied numerically.

Round-based models are very common message-passing models; combinatorial topology applied to distributed computing provides sweeping results like general lower bounds. We combine both to study the computability of k-set agreement. Among all the possible round-based models, we consider oblivious ones, where the constraints are given only round per round by a set of allowed graphs. And among oblivious models, we focus on closed-above ones, that is models where the set of possible graphs contains all graphs with more edges than some starting graphs. These capture intuitively the underlying structure required by some communication model, like containing a ring. We then derive lower bounds and upper bounds in one round for k-set agreement, such that these bounds are proved using combinatorial topology but stated only in terms of graph properties. These bounds extend to multiple rounds when limiting our algorithms to be oblivious - recalling only pairs of processes and initial value, not who send what and when.

Model-Based Testing (MBT) relies on models of a System Under Test (SUT) to derive test cases for said system. While Finite State Machine (FSM), workflow, etc. are widely used to derive test cases for WIMP applications (i.e. applications depending on 2D widgets such as menus and icons), these notations lack the expressive power to describe the interaction techniques and behaviors found in post-WIMP applications. In this paper, we aim at demonstrating that thanks to ICO, a formal notation for describing interactive systems, it is possible to generate test cases that go beyond the state of the art by addressing the MBT of advanced interaction techniques in post-WIMP applications., (undefined)

International audience; Robot interacting with exible object, and particularly with human in movement, is an increasing topic in several applications of today. It is particularly interesting and challenging in term of modeling and control because of the human variability, uncertainty and non-linearity. In the current work, we propose an original approach to model and control the interaction between a 1-dof robotic system and a human. While the human model includes a nonlinear biomechanical model, the nonlinearity is accounted and compensated for in a feedforward controller. Then a robust H1 feedback control is added in order to allow the closed-loop satisfy some specified performances under possible uncertainties and under external disturbance such as noise. The feedforward-feedback control is afterwards extensively verified in simulation which confirm its efficiency.

International audience; In this paper, the location of masses and of a piezoelectric patch for energy harvesting reported onto a vibrating cantilever beam is studied and optimized. To this aim, a genetic algorithm is adapted and utilized to optimize the voltage amplitude generated by the piezoelectric patches by choosing attachment mass, attachment mass moment of inertia, attachment location, piezoelectric patch location and force location on the beam as parameters. While an analytical approach is proposed to evaluate the voltage amplitude, a multi-layer perceptron neural network is trained by the derived characteristic matrix to obtain an approximate function for natural frequencies based on the attachment parameters. The trained network is then used in the core of genetic algorithm to find the best optimization variables for any excitation frequency. Numerical simulation by COMSOL Multiphysics finite element software validates the calculated voltage by analytical approach. The optimization method successfully matches the natural frequency of the beam with the excitation frequency which therefore maximizes the output energy. On the other hand, the superiority of the optimized design over the conventional configuration in harvesting the energy at high frequency excitation is also approved.

Nowadays, the concept of programmable matter paves the way for promising applications such as reshaping an object to test different configurations, modeling or rapid prototyping. Based on elementary modules, such matter can be arranged and disassembled easily according to the needs of the designers. Several solutions have been proposed to implement this concept. Most of them are based on modular self-reconfigurable robotics (SMR) that can work together and move relatively to one another in order to change their configuration. Achieving such behavior requires to solve some technological challenges in particular module&rsquo, s geometry and actuation. In this paper, we build and develop a proof of concept for a catom based on electrostatic actuation. The modeling and analysis of the actuator functioning as catom is given after a comparison of various possible actuation. Simulations as well as experiments validations are afterwards carried out to confirm and demonstrate the efficiency of electrostatic actuation to achieve latching capabilities of the proposed catom.