Tesi sul tema "Stabilité en temps fixe"
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Lopez, Ramirez Francisco. "Control and estimation in finite-time and in fixed-time via implicit Lyapunov functions". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I063/document.
This work presents new results on analysis and synthesis of finite-time and fixed-time stable systems, a type of dynamical systems where exact convergence to an equilibrium point is guaranteed in a finite amount of time. In the case of fixed-time stable system, this is moreover achieved with an upper bound on the settling-time that does not depend on the system’s initial condition.Chapters 2 and 3 focus on theoretical contributions; the former presents necessary and sufficient conditions for fixed-time stability of continuous autonomous systems whereas the latter introduces a framework that gathers ISS Lyapunov functions, finite-time and fixed-time stability analysis and the implicit Lyapunov function approach in order to study and determine the robustness of this type of systems.Chapters 4 and 5 deal with more practical aspects, more precisely, the synthesis of finite-time and fixed-time controllers and observers. In Chapter 4, finite-time and fixed-time convergent observers are designed for linear MIMO systems using the implicit approach. In Chapter 5, homogeneity properties and the implicit approach are used to design a fixed-time output controller for the chain of integrators. The results obtained were verified by numerical simulations and Chapter 4 includes performance tests on a rotary pendulum
Saidi, Karima. "Stabilisation d’une classe d’EDP non linéaire. Application à l’équation de Vlasov-Poisson". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0225.
The work presented in this thesis concerns the stabilization of a class of nonlinear partialdifferential equations. It is a discretized model of the Vlasov-Poisson equation describing the spatial and temporal evolution, in a plasma, of a distribution function of charged particles. In a first step, we addressed the stabilization of the dynamical systems in fixed time (i.e. stabilization in finite time with a uniformly bounded). Criteria relaxing existing results in the literature have been established. Indeed, we have shown that, for a dynamical system, the combination of slow stability (in the polynomial sense) and fast stability (in the finite time sense) leads to a stability in fixed time. Various applications on the discretized Vlasov-Poisson system also concern the double integrator system with observer and the bilinear systems in infinite dimension where for each of these systems, the stabilizing feedback and/or observers in fixed time are constructed and numerically tested. In a second step, we are interested in the small time stabilization of time varying dynamical systems. In fact, the notion of small time is commonly used in theory of controllability. For stabilization, this small time is located between finite time and the fixed time. We have developed theoretical results based on the energy method guaranteeing the disappearance of the solution in small time. This is obtainedby means of a time excitation of a positive function not integrable in the sense of Lebesgue. Then, we have applied our results on model examples such as the transport equation with boundary control, the wave equation subject to a boundary control of the Wentzell type. Also, for finite and infinite dimensional bilinear systems which are, in addition, typical discretized Vlasov-Poisson models. For each system, we have elaborated its feedback whose construction is based on the integration of temporal and uniform excitations
Chu, Xing. "Commande distribuée, en poursuite, d'un système multi-robots non holonomes en formation". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0035/document.
The main aim of this thesis is to study the distributed tracking control problem for the multi-robot formation systems with nonholonomic constraint, of which the control objective it to drive a team of unicycle-type mobile robots to form one desired formation configuration with its centroid moving along with another dynamic reference trajectory, which can be specified by the virtual leader or human. We consider several problems in this point, ranging from finite-time stability andfixed-time stability, event-triggered communication and control mechanism, kinematics and dynamics, continuous-time systems and hybrid systems. The tracking control problem has been solved in this thesis via developing diverse practical distributed controller with the consideration of faster convergence rate, higher control accuracy, stronger robustness, explicit and independent convergence time estimate, less communication cost and energy consumption.In the first part of the thesis, we first study the finite-time stability for the multi-robot formation systems in Chapter 2. To improve the pior results, a novel class of finite-time controller is further proposed in Chapter 3, which is also called fixed-time controller. The dynamics of nonholonomic multi-robot formation systems is considered in Chapter 4. In the second part, we first investigate the event-triggered communication and control mechanism on the nonholonomic multi-robot formation tracking systems in Chapter 5. Moreover, in order to develop a digital implement scheme, we propose another class of periodic event-triggered controller based on fixed-time observer in Chapter 6
Anggraeni, Pipit. "Consensus décentralisé de type meneur/suiveur pour une flotte de robots coopératifs soumis à des contraintes temporelles". Thesis, Valenciennes, 2019. http://www.theses.fr/2019VALE0012/document.
Nowadays, robots have become increasingly important to investigate hazardous and dangerous environments. A group of collaborating robots can often deal with tasks that are difficult, or even impossible, to be accomplished by a single robot. Multiple robots working in a cooperative manner is called as a Multi-Agent System (MAS). The interaction between agents to achieve a global task is a key in cooperative control. Cooperative control of MASs poses significant theoretical and practical challenges. One of the fundamental topics in cooperative control is the consensus where the objective is to design control protocols between agents to achieve a state agreement. This thesis improves the navigation scheme for MASs, while taking into account some practical constraints (robot model and temporal constraints) in the design of cooperative controllers for each agent, in a fully decentralized way. In this thesis, two directions are investigated. On one hand, the convergence rate is an important performance specification to design the controller for a dynamical system. As an important performance measure for the coordination control of MASs, fast convergence is always pursued to achieve better performance and robustness. Most of the existing consensus algorithms focus on asymptotic convergence, where the settling time is infinite. However, many applications require a high speed convergence generally characterized by a finite-time control strategy. Moreover, finite-time control allows some advantageous properties but the settling time depend on the initial states of agents. The objective here is to design a fixed-time leader-follower consensus protocol for MASs described in continuous-time. This problem is studied using the powerful theory of fixed-time stabilization, which guarantee that the settling time is upper bounded regardless to the initial conditions. Sliding mode controllers and sliding mode observers are designed for each agent to solve the fixed-time consensus tracking problem when the leader is dynamic. On the other hand, compared with continuous-time systems, consensus problem in a discrete-time framework is more suitable for practical applications due to the limitation of computational resources for each agent. Model Predictive Control (MPC) has the ability to handle control and state constraints for discrete-time systems. In this thesis, this method is applied to deal with the consensus problem in discrete-time by letting each agent to solve, at each step, a constrained optimal control problem involving only the state of neighboring agents. The tracking performances are also improved in this thesis by adding new terms in the classical MPC technique. The proposed controllers will be simulated and implemented on a team of multiple Mini-Lab Enova Robots using ROS (Robotic Operating System) which is an operating system for mobile robots. ROS provides not only standard operating system services but also high-level functionalities. In this thesis, some solutions corresponding to problem of connection between multiple mobile robots in a decentralized way for a wireless robotic network, of tuning of the sampling periods and control parameters are also discussed
Harb, Ali. "Faisabilité. Méthodes non standard pour la stabilité des réseaux de files d'attente. GI/GI/q + G". Rouen, 1998. http://www.theses.fr/1998ROUES075.
Bui, Van Bien. "La stabilité du filtre non-linéaire en temps continu". Thesis, Nice, 2016. http://www.theses.fr/2016NICE4002/document.
The filtering problem consists of estimating the state of a dynamic, called signal which is often a Markov process, from the noisy observation of the past states. In this thesis, we consider a filtering model in continuous time for the diffusion process. The aim is to study the stability of the optimal filter with respect to its initial condition beyond the mixing (or quasi – mixing) hypothesis for the transition kernel
Bhiri, Bassem. "Stabilité et stabilisation en temps fini des systèmes dynamiques". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0100/document.
This dissertation deals with the finite time stability and the finite time stabilization of dynamic systems. Indeed, it is often important to ensure that during the transient regime, the state trajectories do not exceed certain predefined limits in order to avoid saturations and excitations of the nonlinearities of the system. Hence the interest is to study the stability of the dynamic system in finite time. A dynamic system is said to be stable in finite time (FTS) if, for any initial state belonging to a predetermined bounded set, the state trajectory remains within another predetermined bounded set for a finite and fixed time. When the system is disturbed, it is called finite time boundedness (FTB). In this manuscript, the goal is to improve the results of finite time stability used in the literature. First, new sufficient conditions expressed in terms of LMIs for the synthesis of an FTB controller by dynamic output feedback have been developed via an original descriptor approach. An original method has been proposed which consists in using a particular congruence transformation. Second, new LMI conditions for the study of finite time stability and finite time stabilization have been proposed for disturbed and undisturbed nonlinear quadratic systems. Third, to obtain even less conservative conditions, new developments have been proposed using polynomial Lyapunov functions
Bhiri, Bassem. "Stabilité et stabilisation en temps fini des systèmes dynamiques". Electronic Thesis or Diss., Université de Lorraine, 2017. http://www.theses.fr/2017LORR0100.
This dissertation deals with the finite time stability and the finite time stabilization of dynamic systems. Indeed, it is often important to ensure that during the transient regime, the state trajectories do not exceed certain predefined limits in order to avoid saturations and excitations of the nonlinearities of the system. Hence the interest is to study the stability of the dynamic system in finite time. A dynamic system is said to be stable in finite time (FTS) if, for any initial state belonging to a predetermined bounded set, the state trajectory remains within another predetermined bounded set for a finite and fixed time. When the system is disturbed, it is called finite time boundedness (FTB). In this manuscript, the goal is to improve the results of finite time stability used in the literature. First, new sufficient conditions expressed in terms of LMIs for the synthesis of an FTB controller by dynamic output feedback have been developed via an original descriptor approach. An original method has been proposed which consists in using a particular congruence transformation. Second, new LMI conditions for the study of finite time stability and finite time stabilization have been proposed for disturbed and undisturbed nonlinear quadratic systems. Third, to obtain even less conservative conditions, new developments have been proposed using polynomial Lyapunov functions
Landry, Mario. "Commande de vol non-linéaire en temps réel d’un drone à voilure fixe". Mémoire, École de technologie supérieure, 2012. http://espace.etsmtl.ca/1010/1/LANDRY_Mario.pdf.
Amini, Hadis. "Stabilisation des systèmes quantiques à temps discrets et stabilité des filtres quantiques à temps continus". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00803170.
De, Kelper Bruno. "Simulation à pas fixe et en temps réel de circuits électriques contenant des interrupteurs". Mémoire, École de technologie supérieure, 2002. http://espace.etsmtl.ca/805/1/DE_KELPER_Bruno.pdf.
Nguyen, Thi Nuyen Chau. "Approximation des temps de réponse des tâches sporadiques à priorité fixe dans les systèmes monoprocesseurs". Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2010. http://www.theses.fr/2010ESMA0014.
Two techniques are used to verify if real-time tasks meet their deadlines : schedulability tests that return a binary result (schedulable or not) and the calculation of the response times (Response Time Analysis - RTA) which determines the length of the longest interval between the release instant and the completion of a task. Both approaches have a pseudo-polynomial time complexity and please note that no polynomial time algorithm is known. In this context, they are not particularly suitable for interactive design of real-time systems or to analyze distributed systems using an holistic analysis. In such scenarios, a pseudo-polynomial time algorithm is slow, since the computations of the task response times are performed many times. Moreover, for some real time systems, such as the control-command systems, it is necessary to know the task worst-case response times and not only the binary decision on the tasks schedulability. In this context, it may be acceptable to use a faster algorithm which provides an approximate analysis instead of the analysis based on exact calculations. As these approximations will produce pessimism in the decision process, it is desirable to quantify this pessimism in such a way as to define a compromise between computation time and resource requirement of processor. That is the reason why, in this work, we propose efficient algorithms to compute upper bounds of worst-case response times and we present results on their qualities in the worst-case (competitive analysis resource augmentation) and in the average (simulations)
Zoghlami, Naïm. "Stabilité et stabilisation en temps fini des ystèmes dynamiques interconnectés et problème de consensus en temps fini". Thesis, Evry-Val d'Essonne, 2014. http://www.theses.fr/2014EVRY0023/document.
This manuscript is dedicated to the study of finite time stability and stabilization of interconnected dynamical systems and finite time consensus problem. After a general introduction, the first part of this thesis focuses on finite time stability and stabilization of perturbed systems and interconnected systems. The second part of this thesis is devoted to the problems of: finite-time consensus, average consensus and finite time stabilization of multi-agent systems. This concept has been addressed by targeting non-linear controlled dynamical systems: with and without drift term. Some protocols are proposed to solve the finite time consensus problem. Many applications and simulations are illustrated
Dauphin, Gabriel. "Application des représentations diffusives à temps discret". Phd thesis, Télécom ParisTech, 2001. http://tel.archives-ouvertes.fr/tel-00005780.
Le première partie consiste en la mise en place des représentations diffusives à temps discret. Certains filtres non-relationnels, notamment les différences frationnaires, sont une agrégation continue de dynamiques purement amorties. Les représentations diffusives s'appliquent à toutes les discrétisations de l'intégration fractionnaire y compris celles pour lesquelles la fonction de transfert n'est pas connue analytiquement. Les filtres diffusifs peuvent être réalisés par un système de dimension infinie. Cette structure est un cadre adapté à l'approximation par un filtre relationnel, à l'analyse asymptotique aux temps longs et à l'élaboration d'un critère de dissipativité.
La deuxième partie consiste à appliquer ces outils pour l'étude des couplages formés de filtres diffusifs et de filtres rationnels positifs. L'application d'un critère de Nyquist prouve la stabilité énergétique. Ces couplages sont en fait la somme d'une partie entière et d'une partie diffusive, ce résultat de décomposition montre que certains couplages sont stables EBSB (entrée-bornée, sortie-bornée). La dissipativité de la réalisation diffusive ainsi que le lemme de Kalman-Yacubovich-Popov montrent notamment la stabilité interne de ces couplages ; une démonstration originale du caractère asymptotique de la stabilité interne est ainsi proposée. Les approches utilisées pour prouver ces stabiblités permettent une analyse asymptotique aux temps longs.
Farhat, Hassan. "Prise en compte des temps et des déplacements en stabilité des pentes". Lyon, INSA, 1990. http://www.theses.fr/1990ISAL0092.
[The aim of this work LS to propose new methods of calculation in slope stability analysis. First, a bibliographical review, on shear behaviour of soils and methods of slope stability analysis, shows the advantage of a displacement formulation. Then, two methods of calculation were proposed. The first takes into account the displacements measured by inclinometers to follow the evolution of a slope. The second method is more general. It permits one to follow the evolution of a slope (stresses and displacements) as a function of the varying boundary conditions. Laws of creep are introduced in the model. The displacement of the slope with time can be controlled. The two methods are validated by comparing the results of the calculation with the sliding measurements of the experimental embankment of Sallèdes (Puy de Dôme) and the sliding of Campagna (Italy). ]
Courchesne, Samuel. "Estimation et validation des dérivées de stabilité et contrôle du modèle dynamique non-linéaire d’un drone à voilure fixe". Mémoire, École de technologie supérieure, 2013. http://espace.etsmtl.ca/1147/1/COURCHESNE_Samuel.pdf.
Agulhari, Cristiano Marcos. "Stabilité et commande des systèmes linéaires variant dans le temps aux paramètres incertains". Phd thesis, INSA de Toulouse, 2013. http://tel.archives-ouvertes.fr/tel-00822689.
Sarmis, Merdan. "Etude de l'activité neuronale : optimisation du temps de simulation et stabilité des modèles". Thesis, Mulhouse, 2013. http://www.theses.fr/2013MULH3848/document.
Computational Neuroscience consists in studying the nervous system through modeling and simulation. It is to characterize the laws of biology by using mathematical models integrating all known experimental data. From a practical point of view, the more realistic the model, the largest the required computational resources. The issue of complexity and accuracy is a well known problem in the modeling and identification of models. The research conducted in this thesis aims at improving the simulation of mathematical models representing the physical and chemical behavior of synaptic receptors. Models of synaptic receptors are described by ordinary differential equations (ODE), and are resolved with numerical procedures. In order to optimize the performance of the simulations, I have implemented various ODE numerical resolution methods. To facilitate the selection of the best solver, a method, requiring a minimum amount of information, has been proposed. This method allows choosing the best solver in order to optimize the simulation. The method demonstrates that the dynamic of a model has greater influence on the solver performances than the kinetic scheme of the model. In addition, to characterize pathogenic behavior, a parameter optimization is performed. However, some parameter values lead to unstable models. A stability study allowed for determining the stability of the models with parameters provided by the literature, but also to trace the stability constraints depending to these parameters. Compliance with these constraints ensures the stability of the models studied during the optimization phase, and therefore the success of the procedure to study pathogen models
Dauphin, Gabriel. "Application des représentations diffusives au temps discret". Paris, ENST, 2001. https://pastel.archives-ouvertes.fr/tel-00005780.
Moulay, Emmanuel. "Une contribution à l'étude de la stabilité en temps fini et de la stabilisation". Phd thesis, Ecole Centrale de Lille, 2005. http://tel.archives-ouvertes.fr/tel-00114333.
La deuxième partie de ce mémoire est consacrée à la stabilisation en utilisant les fonctions de Lyapunov contrôlées. Une large part est dédiée à la stabilisation en temps fini.
Taousser, Fatima Zohra. "Analyse de stabilité des systèmes à commutations sur un domaine de temps non-uniforme". Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0038/document.
This thesis deals with the stability analysis of switched systems that evolve on non uniform time domain by introducing the time scale theory. We are interested mainly in dynamical linear switched systems defined on particular time scale T = P{tσk ,tk+1} = ∪∞k=0[tσk, tk+1]. The studied system switches between a continuous-time dynamical subsystem on the intervals ∪∞k=0[tσk, tk+1[ and a discrete-time dynamical subsystem on instants ∪∞k=0{tk+1} (a discrete time) with a time-varying discrete step. In a first part, sufficient conditions are given to guarantee the exponential stability of this class of switched systems. Then necessary and sufficient conditions for stability are given by determining a region of exponential stability. In the second part, the stability of this class of switched systems with nonlinear uncertainties, is treated using majoration of the solution, and after that by introducing the approach of a common Lyapunov function. The third part is devoted to the consensus problem under intermittent information transmissions where the closed-loop multi-agent system can be represented as a switched system using a combination of linear continuous-time and linear discrete-time systems
Kabakouala, André Bernard. "Comportement en temps long de quelques EDPs dispersives". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4001/document.
No summary available
Larreta-Garde, Véronique. "Influence de l'espace sur le comportement cinétique et la stabilité de fractions subcellulaires : exemple des chromatophores immobilisés". Compiègne, 1985. http://www.theses.fr/1985COMPDE45.
Flouzat, Christophe. "Modulateurs sigma-delta passe-bande en temps continu". Paris 11, 2003. http://www.theses.fr/2003PA112339.
Shen, Dawei. "Problèmes de stabilité en relativité générale". Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS014.
This thesis is devoted to study the stability of particular solutions to Einstein vacuum equations: the Minkowski spacetime and Kerr black holes. More precisely, this thesis contains four main results. The first result concerns the stability of Minkowski spacetime outside an outgoing null cone and contains a generalization of the result of Klainerman-Nicolo. The second result shows the global nonlinear stability of the Minkowski space under the assumption of minimal decay on the initial data generalizing a result of Bieri. The third result provides a new proof of Kerr stability in external regions, obtained by Caciotta-Nicolo. The common feature of these three works is the application of the r^p-weighted estimate method introduced by Dafermos-Rodnianski, as an alternative to the vectorfield method, to obtain control of the curvature terms. The last result provides a construction of GCM hypersurfaces, which is a part of a sequence of five works (the four others are due to Klainerman-Szeftel and Giorgi-Klainerman-Szeftel) establishing Kerr stability for small angular momentum
Toldo, Sandrine. "Convergence de filtrations ; application à la discrétisation de processus et à la stabilité de temps d'arrêt". Phd thesis, Université Rennes 1, 2005. http://tel.archives-ouvertes.fr/tel-00011277.
Fedelich, Bernard. "Trajets d'équilibre des systèmes mécaniques dissipatifs à comportement indépendant du temps physique". Marne-la-vallée, ENPC, 1990. http://www.theses.fr/1990ENPC9018.
Cavichioli, Gonzaga Carlos. "Analyse de stabilité et de performances d'une classe de systèmes non-linéaires à commutations en temps discret". Phd thesis, Université de Lorraine, 2012. http://tel.archives-ouvertes.fr/tel-00762873.
Cavichioli, Gonzaga Carlos Alberto. "Analyse de stabilité et de performance d'une classe de systèmes non-linéaires à commutations en temps discret". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0086/document.
In this PhD thesis, several problems of stability analysis and control design of discrete-time switched nonlinear systems are addressed. As main contribution, a new class of Lyapunov functions which takes the nonlinearity into account has been proposed. We show that these functions are suitable to solve the classical stability analysis problem of linear systems connected to a cone bounded nonlinearity. Instead of the original Lyapunov Lur'e function, the assumptions about the nonlinearity variation are not required. Furthermore, the local stability analysis and control synthesis problems of Lur'e systems subject to control saturation are tackled by considering the level set of our function as an estimate of the basin of attraction. We expose that this estimate, which is given by non-convex and disconnected sets, is less conservative than ellipsoidal sets. We extend these results in order to deal with the problems of stability analysis and stabilization of discrete-time switched nonlinear systems. On one hand, we consider the case of arbitrary switching such that our sufficient conditions assure the properties of stability for all possible switching rules. In this framework, we highlight that our function is able to provide a suitable estimate of the basin of attraction. On the other hand, we tackle the problem of switching rule design aiming at the stabilization of discrete-time switched systems with nonlinear modes. We propose a switching strategy depending on the minimum of our switched Lyapunov Lur'e function. Hence, our framework leads to state space partitions, related to the mode activation, which are not restricted to conic sets, commonly exhibited by the switched quadratic functions approaches
Cavichioli, Gonzaga Carlos Alberto. "Analyse de stabilité et de performance d'une classe de systèmes non-linéaires à commutations en temps discret". Electronic Thesis or Diss., Université de Lorraine, 2012. http://www.theses.fr/2012LORR0086.
In this PhD thesis, several problems of stability analysis and control design of discrete-time switched nonlinear systems are addressed. As main contribution, a new class of Lyapunov functions which takes the nonlinearity into account has been proposed. We show that these functions are suitable to solve the classical stability analysis problem of linear systems connected to a cone bounded nonlinearity. Instead of the original Lyapunov Lur'e function, the assumptions about the nonlinearity variation are not required. Furthermore, the local stability analysis and control synthesis problems of Lur'e systems subject to control saturation are tackled by considering the level set of our function as an estimate of the basin of attraction. We expose that this estimate, which is given by non-convex and disconnected sets, is less conservative than ellipsoidal sets. We extend these results in order to deal with the problems of stability analysis and stabilization of discrete-time switched nonlinear systems. On one hand, we consider the case of arbitrary switching such that our sufficient conditions assure the properties of stability for all possible switching rules. In this framework, we highlight that our function is able to provide a suitable estimate of the basin of attraction. On the other hand, we tackle the problem of switching rule design aiming at the stabilization of discrete-time switched systems with nonlinear modes. We propose a switching strategy depending on the minimum of our switched Lyapunov Lur'e function. Hence, our framework leads to state space partitions, related to the mode activation, which are not restricted to conic sets, commonly exhibited by the switched quadratic functions approaches
Thomas, Johan Deville Yannick Hosseini Shahram. "Algorithmes temporels rapides à point fixe pour la séparation aveugle de mélanges convolutifs et/ou sous-déterminés". Toulouse (Université Paul Sabatier, Toulouse 3), 2008. http://thesesups.ups-tlse.fr/215.
Rhim, Achour. "Prévision du temps de vie du lien pour améliorer la stabilité de routage dans les réseaux Ad hoc". Mémoire, École de technologie supérieure, 2009. http://espace.etsmtl.ca/77/1/RHIM_Achour.pdf.
Moufid, Mohamed. "Questions de stabilité de systèmes complexes dans le champ de l'attraction terrestre". Université de Franche-Comté. UFR des sciences et techniques, 1986. http://www.theses.fr/1986BESA2025.
Cilas, Christian. "Stabilité des caractères dans le temps chez les plantes pérennes : étude génétique de la capacité productive chez Coffea spp". Paris 11, 2004. http://www.theses.fr/2004PA112032.
With perennial plants, the efficiency of genetic improvement is limited by particular constraints associated with the economic life span of the crops. Although ways of estimating genetic parameters have been improved, the characters on which analyses are based do not always have a very precise biological sense. For exemple, when considering fruits or seeds, as in the case of coffee trees, how many years of observations does it take to define the "production" character? How can variations in characters over time be integrated with a view to defining a breeding objective in which frequent reference is made to stability and sustainability. After an initial section characterizing competition between fruit production and vegetative growth, two complementary approaches have been taken to try and answer these questions. The first consisted in analysing different trials and mating designs for the species Coffea arabica and Coffea canephora. The particularity of those trials, notably for C. Canephora, lay in the way they were monitored, over a large number of years (14 years). It was found that first cycle production (before coffee trees are cut back for the first time) was not always sufficient for predicting the production of the following cycles. In addition, indexes are proposed for characterizing how planting material distributes its annual yields over time. The second approach consisted in identifying architectural characters able to predict the production capacity of the coffee trees. Thus, the squat coffee trees, with short inter nodes, constitute the morphotypes to be promoted
Altazin, Estelle. "Stabilité et replanification d’un système ferroviaire dense". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEM008.
While operating a dense railway system, minor incidents can easily generate delays. Those delays can spread and rapidly amplify along one line, and sometimes to other lines sharing the infrastructure, rolling-stock units or drivers. This thesis addresses the real-time decision-making problem while operating a dense railway system. Dense railway operations are first presented, along with their properties and weaknesses. The notion of stability for a dense railway system is introduced and discussed. Related problems and approaches of the literature are reviewed, both in railway and in urban transportation, and the considered real-time rescheduling problem is presented. A first resolution approach, based on an Integer Linear Programming model, is proposed, and numerical experiments on real data are analyzed. They show the relevance of the rescheduling problem. A more general approach is then proposed, that iterates between an optimization module and a simulation module. All operational actions are considered in the iterative approach, and the use of simulation allows for a precise evaluation of the impact of actions on passengers. This new approach is also multi-objective, thus different solutions can be proposed to the decision makers. A rescheduling tool has been implemented, using the iterative approach, and connected to industrial data flows. Real-life experiments on a Transilien line proved that the tool, and thus the iterative approach, fulfills the decision makers’ expectations and helps reducing the duration of perturbations and their impact on passengers
Michel, Patrice. "Estimation en temps réel des modes souples des voilures de grande dimension". Toulouse, INPT, 2003. http://www.theses.fr/2003INPT059H.
In the aeronautics, the vibrations of an aerofoil can create a critical problem of stability. Aerofoils can even destroy the structure of the plane or simply reduce the quality of the flight. They can also have as a consequence the excitation of badly damped modes which can reduce the performance of laws of orders (based on a rigid model of the plane modifiyng its global dynamics). No long time ago, the rigidity of the aerofoils ensured a frequential decoupling between the structural modes and the piloting modes. Technico-economic constraints lead the aeronautical manufacturers to develop light planes of great scale. Thus, the design of large planes with flexible structure resulted in having these two sets of modes at similar frequencies. In such a context, it becomes difficult to separate the different modes without limiting the maneuvrability of the plane. As a consequence, alternative solutions have be studied. The objective of this thesis is to propose a real time algorithm able to estimate frequencies, amplitudes and possibly the phases of modes with the requirements related to embarked calculation under industrial constraints
Dagbagi, Mohamed. "Simulation temps-réel embarquée de systèmes électriques au moyen de FPGA". Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0808/document.
The aim of this thesis work is to develop an IP-Library of FPGA-based embedded real-time simulator IPs (Intellectual Properties) that simulate different elements of an electrical system. These IPs have been designed to be used not only for Hardware-In-the-Loop (HIL) testing of digital controllers but also for low cost embedded control applications, where the simulator IP and the controller are both implemented and run altogether in the same FPGA device. This emerging class of real-time simulators is expected to be more and more included in the next generation of digital controllers. Indeed, such embedded real-time simulator IPs can be advantageously embedded within digital controllers to ensure functions like observation, estimation, diagnostic or health-monitoring. Conversely to the HIL case, the main challenge when designing such simulator IPs is to cope with their complexity having in mind that, in the case of embedded systems, the available hardware resources are limited due to the cost. Furthermore, this challenge is strengthened by the need of very short simulation time-steps which is typically the case when simulating power converters.To develop these IPs, dedicated design guidelines have been proposed to be followed to manage the complexity of these simulator IPs (model solver, numerical solver, time-step, data conditioning) with regards to the timing and the area/cost constraints (computation time limit, limited hardware resources …).The simulators IPs to be developed have been organized into two main categories: those dedicated to electromagnetic elements of an electrical system and those dedicated to their switching elements.The first category gathers elements where electric, magnetic phenomena are modelized in addition to mechanical phenomena (for moving systems) and potentially thermal phenomena. Three cases are dealt with: the embedded real-time simulator of a three-phase synchronous machine, the one of a three-phase induction machine and the one of a brushless synchronous generator. Also, the advantages of using delta transformation to improve the stability of the numerical solver when short simulation time-step and fixed-point (with limited data precision) are used, have been studied.The second category concerns switching elements such as power converters where switching events are considered. Here again, several converter topologies have been studied: a half-wave rectifier, a buck DC-DC converter, a bidirectional buck DC-DC converter, a H-bridge DC-DC converter, a single-phase H-bridge DC-AC converter, a three-phase voltage source inverter, a three-phase diode rectifier and a three-phase PWM rectifier. For all these IPs, the Associated Discrete Circuit (ADC) modeling approach is adopted.The embedded real-time simulator IP of the three-phase PWM rectifier has been applied in the context of an embedded application. The latter consists of a fault-tolerant control of a grid-connected voltage source rectifier. Thus, this simulator IP is associated with the one of a three-phase RL-filter and are both implemented within the rectifier controller to estimate the grid currents. These currents are injected in the controller in the case of a current sensor fault. The ability of this estimator to guarantee the service continuity in the case of faults is validated through HIL tests and experiments
Bernuau, Emmanuel. "Robustesse et stabilité des systèmes non-linéaires : un point de vue basé sur l'homogénéité". Phd thesis, Ecole Centrale de Lille, 2013. http://tel.archives-ouvertes.fr/tel-00917798.
Ariba, Yassine. "Sur la stabilité des systèmes à retards variant dans le temps : théorie et application au contrôle de congestion d'un routeur". Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00442454.
Petit, Gérard. "Observations VLBI des pulsars millisecondes pour le raccordement des systèmes de référence célestes et la stabilité des échelles de temps". Observatoire de Paris, 1994. https://hal.science/tel-02095454.
Bouazza, Kheir-Eddine. "Commande basée sur des observateurs pour les systèmes non-linéaires en temps discret". Nancy 1, 2004. http://www.theses.fr/2004NAN10171.
Research activities presented in this thesis concerne the stabilisation, with obserber-based controllers, of discrete-time nonlinear systems. The approach which we proposed doesn't require a particular structure of the output contrary to the methods based on the the passivity theory. Unlike the jurdjevic-quinn method, it doesn't need the stability of the free dynamics. A lyapunov function common to a great number of systems is used for the analysis of stability. Moreover it has the advantage of being simply implementable. Using the results established previously, synthesis of a control law based on an extended kalman observer was given. The third section presents an observer based controller which stabilizes globally exponentially a class of nonlinear systems. An extension to delay systems was established. In the last section, we present a simple conditions in linear matrix inequalities form, which stbilizes asymptotically a large class of delay nonlinear systems. Some other conditions allowing the synthesis of observers for different classes of nonlinear systems were presented
Bernuau, Emmanuel. "Robustesse et stabilité des systèmes non-linéaires : un point de vue basé sur l’homogénéité". Thesis, Ecole centrale de Lille, 2013. http://www.theses.fr/2013ECLI0015/document.
The purpose of this work is the study of stability and robustness properties of nonlinear systems using homogeneity-based methods. Firstly, we recall the usual context of homogeneous systems as well as their main features. The sequel of this work extends the homogenization of nonlinear systems, which was already defined in the framework of weighted homogeneity, to the more general setting of the geometric homogeneity. The main approximation results are extended. Then we develop a theoretical framework for defining homogeneity of discontinuous systems and/or systems given by a differential inclusion. We show that the well-known properties of homogeneous systems persist in this context. This work is continued by a study of the robustness properties of homogeneous or homogenizable systems. We show that under mild assumptions, these systems are input-to-state stable. Finally, the last part of this work consists in the study of the example of the double integrator system. We synthesize a finite-time stabilizing output feedback, which is shown to be robust with respect to perturbations or discretization by using techniques developed before. Simulations conclude the theoretical study of this system and illustrate its behavior
Ben, Rejeb Jihene. "Analyse de stabilité et synchronisation des systèmes singulièrement perturbés". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0117/document.
This PhD thesis is dedicated to the study of stability and control design for singularly perturbed systems. In the first part, we introduce and analyze a general class of singularly perturbed linear hybrid systems, in which the slow or fast nature of the variables is mode-dependent. Our stability analysis is based on classical results of Lyapunov’s theory for singularly perturbed systems. A second part of this work presents the design of a decentralized control strategy that allows singularly perturbed multi-agent systems to achieve synchronization with global performance guarantees. To avoid the use of centralized information related to the interconnection network structure, the problem is solved by rewriting the synchronization problem in terms of stabilization of a singularly perturbed uncertain linear system
Sainlaud, Chloé. "Caractérisation du veillissement de matrices alimentaires enrichies à base lipidique. Etude de l'évolution de leurs propriétés texturales au cours du temps". Thesis, Normandie, 2021. http://www.theses.fr/2021NORMR009.
The objective of this work was to determine the origin of textural modifications observed during the storage of a food product, the product Plumpy’Nut®. It is a complex matrix composed of crystalline, amorphous, liquid and vitreous constituents. Its composition gives it the particularity of containing at room temperature, a fraction in the liquid state and a fraction in the solid state. A first global analysis allowed to identify two ingredients which are driving mainly the structure and thermal behavior of the product and, by extension, its rheological properties. These two ingredients are palm oil and an element called “stabilizer” (blend of fully hydrogenated fat, monoand diglycerides). Crystallization mechanisms of these two constituents were studied by means of X-Ray scattering and diffraction analyses, with a particular interest in the roles of cooling kinetics. We showed that palm oil crystallizes mainly under polymorphic form β’ and that adding the “stabilizer” induces a crystallization partially under the most stable polymorphic form β, no matter the cooling profile considered. The stabilizer initiates a crystallisation of palm oil at higher temperature compared to palm oil alone (around 35°C instead of 25°C). The lamellar configuration adopted by triglycerides depends on the cooling profile considered. From a rheological point of view, the viscosity evolution of the product Plumpy’Nut® versus temperature is well correlated with the crystallization dynamics of Palm oil-Stabilizer blend. The aging of the product Plumpy’Nut® considering several storage and processing conditions, was studied during 26 months by means of several physical-chemical analyses. The origin of the gradual increase of the products firmness over time depends mainly on storage temperature. At low temperature (5°C), post-crystallization phenomenon of lipids dominates while at higher temperature (40°C), the chemical aging and oil rising predominate
Ducros, Florence. "Maintien en conditions opérationnelles pour une flotte de véhicules : étude de la non stabilité des flux de rechange dans le temps". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS213/document.
This thesis gathers methodologicals contributions to simulate the need of replacement equipment for a vehile fleet. Systems degrade with age or use, and fail when they do not fulfill their mission. The user needs an assurance that the system is operational during its useful life. A support contract obliges the manufacturer to remedy a failure and to keep the system in operational condition for the duration of the MCO contract.The management of support contracts or the extension of support requires knowledge of the equipment lifetime and also the uses condition of vehicles, which depends on the customer. The analysis of customer returns or RetEx is then an important tool to help support the decision of the industrial. In reliability or warranty analysis, engineers must often deal with lifetimes data that are non-homogeneous. Most of the time, this variability is unobserved but has to be taken into account for reliability or warranty cost analysis.A further problem is that in reliability analysis, the data is heavily censored which makes estimations more difficult. We propose to consider the heterogeneity of lifetimes by a mixture and competition model of two Weibull laws. Unfortunately, the performance of classical estimation methods (maximum of likelihood via EM, Bayes approach via MCMC) is jeopardized due to the high number of parameters and the heavy censoring.To overcome the problem of heavy censoring for Weibull mixture parameters estimation, we propose a Bayesian bootstrap method, called Bayesian RestorationMaximization.We use an unsupervised clustering method to identify the profiles of vehicle uses. Our method allows to simulate the needs of spare parts for a vehicles fleet for the duration of the contract or for a contract extension
Laget, Michaël. "Stabilité d'éléments superlourds au voisinage de Z=120 testée par l'étude de leurs temps de fission déduits par la méthode du blocage cristallin". Paris 11, 2007. http://www.theses.fr/2007PA112234.
Rigault, Cyril. "Etude mathématique de modèles cinétiques pour la gravitation, tenant compte d'effets relativistes : stabilité, solutions autosimilaires". Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00787487.
George, Jonathan Robert. "Délignification prolongée en milieu alcalin à l'aide d'un réacteur à lit fixe et à faible temps de passage : application à la fabrication de la pâte à papier". Grenoble INPG, 1998. http://www.theses.fr/1998INPG0052.
Ben, Rejeb Jihene. "Analyse de stabilité et synchronisation des systèmes singulièrement perturbés". Electronic Thesis or Diss., Université de Lorraine, 2017. http://www.theses.fr/2017LORR0117.
This PhD thesis is dedicated to the study of stability and control design for singularly perturbed systems. In the first part, we introduce and analyze a general class of singularly perturbed linear hybrid systems, in which the slow or fast nature of the variables is mode-dependent. Our stability analysis is based on classical results of Lyapunov’s theory for singularly perturbed systems. A second part of this work presents the design of a decentralized control strategy that allows singularly perturbed multi-agent systems to achieve synchronization with global performance guarantees. To avoid the use of centralized information related to the interconnection network structure, the problem is solved by rewriting the synchronization problem in terms of stabilization of a singularly perturbed uncertain linear system
Granados, alfaro Ricardo. "Analyse de temps et caractérisation d'horloges pour un radar bistatique pour la tomographie d'astéroïdes". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT090.
Small bodies, like comets and asteroids, are of interest for the study of the origin of the Solar System since they have experienced little changes throughout time. Therefore, by understanding their evolution we can learn about the evolution of the Solar System itself. This information can be useful for future space exploration or for planetary defense. Nowadays, there are several space missions studying or about to study small bodies, but only a few instruments are destined to study the interior of small body cores.Radio waves interact with the medium they are propagating through and will undergo different modifications depending on the properties of the material. Therefore, radar is the ideal method to study the internal structure of an asteroid. The wave's properties, such as its velocity, will be affected by its travel through the nucleus dependent on the dielectric properties of the asteroid. We propose a new bi-static low-frequency radar (LFR) based on the instrument CONSERT which was onboard the Rosetta mission. This LFR primary objective is to measure the propagation delay between two electronics, one posed on the asteroid’s surface and the other orbiting around it. The signal will be transmitted through the body’s nucleus and will be affected by its composition and heterogeneity. By measuring different signal characteristics, such as the propagation delay, we can deduce the composition properties of the object.The main objective of this thesis is to study and understand how the clock drift between radar electronics will affect the measurement of the propagation delay in order to propose compensation methods to improve science return. The initial step of the thesis is to provide an understanding of the clock signal generation and how the stability of the signal will be affected over time by different processes like temperature, the voltage supply, or aging. To understand how these instabilities will impact the propagation delay measurement, we analyze the long scale drift of radar instruments. For this, we developed a time model of the radar based on time events. The model was used to build a simulator using a simple model of the clock signal generation. With this simulator, we show that the time errors have a different effect on the bi-static radar at different time scales, but that these different time scales are correlated. We propose a method to estimate clock drift from radar data to compensate for time errors.To validate the model, a test bench is designed and developed measuring time differences between two clocks. Using the test bench data as input for the simulator allows to estimate the impact on instrument performances and to estimate performances of the compensation methods. The data from the test bench is used for the validation of the selected clocks for the mission and will be used for their characterization. This clock characterization will help to improve the simulator for different tests, as we can include the real models for frequency instabilities.To conclude, we present the limitations of the compensation methods, as well as the improvements in the electronic design and operation of the instrument as a result of the time analysis