Tesi sul tema "Problèmes en ligne"
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Jolivet, Frederic. "Approches "problèmes inverses" régularisées pour l'imagerie sans lentille et la microscopie holographique en ligne". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSES012/document.
In Digital Imaging, the regularized inverse problems methods reconstruct particular information from measurements and an image formation model. With an inverse problem that is ill-posed and illconditioned, and with the used image formation mode! having few constraints, it is necessary to introduce a priori conditions in order to restrict ambiguity for the inversion. This allows us to guide the reconstruction towards a satisfying solution. The works of the following thesis delve into the development of reconstruction algorithms of digital holograms based on large-scale optimization methods (smooth and non-smooth). This general framework allowed us to propose different approaches adapted to the challenges found with this unconventional imaging technique: the super-resolution, reconstruction outside the sensor's field, the color holography and finally, the quantitative reconstruction of phase abjects (i.e. transparent). For this last case, the reconstruction problem consists of estimating the complex 2D transmittance of abjects having absorbed and/or dephased the light wave during the recording of the hologram. The proposed methods are validated with the help of numerical simulations that are then applied on experimental data taken from the lensless imaging or from the in-line holographie microscopy (coherent imaging in transmission, with a microscope abject glass). The applications range from the reconstruction of opaque resolution sights, to the reconstruction of biological objects (bacteria), passing through the reconstruction of evaporating ether droplets from a perspective of turbulence study in fluid mechanics
Salim, Soufian Antoine. "Analyse discursive multi-modale des conversations écrites en ligne portées sur la résolution de problèmes". Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4074/document.
We are interested in problem-solving online written conversations. These conversations may be found on online channels such as forums, mailing lists or chat rooms. In the literature, human interactions are usually modelled in terms of dialogue acts. Dialogue acts are typically used to represent the discursive functions of utterances in dialogue. We want to use dialogue acts for the analysis of online written conversations. Well-defined methods and models allowing for the fine-grained analysis of these conversations would represent a solid framework to support different user-assistance and dialogue analysis systems. This would represent an important stake for the customer support industry, but could also be used to improve collaborative assistance platforms that are accessed daily by millions of users. However, current conversations analysis techniques were not developed with written online conversations in mind. It is necessary to adapt existing resources for these conversations. This effort is related to the field of research in computer-mediated conversations (CMC). Our goal is to build a dialogue act model for problem-solving online written conversations, and to offer tools for the automatic recognition of these acts
Tisserand, Arnaud. "Adéquation arithmétique architecture, problèmes et étude de cas". Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 1997. http://tel.archives-ouvertes.fr/tel-00445752.
Zaid, Abdelkarim. "Problèmes didactiques d'une documentation et d'une assistance pédagogique en ligne pour des ingénieurs en formation en alternance". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2004. http://tel.archives-ouvertes.fr/tel-00136834.
Hachicha, Marouane. "Modélisation de hiérarchies complexes dans les entrepôts de données XML et traitement des problèmes d'additivité dans l'analyse en ligne XOLAP". Thesis, Lyon 2, 2012. http://www.theses.fr/2012LYO22016/document.
Since its inception in 1998, the eXtensible Markup Language (XML) has emerged as a standard for data representation and exchange over the Internet. XML provides an opportunity for modeling data structures that are not easily represented in relational systems. In this context, XML data warehouses nowadays form the basis of several decision-support applications exploiting heterogeneous data (little structured and coming from various sources) bearing complex structures, such as complex hierarchies. In this thesis, we propose a novel XOLAP (XML-OLAP) approach that automatically detects and processes summarizability issues at query time, without requiring any particular expertise from the user. Thus, at the logical level, we choose XML data trees, so-called multidimensional data trees, to model the multidimensional structures (facts, dimensions, measures and complex hierarchies) of XML data warehouses. In order to query multidimensional data trees, we model user queries as XML pattern trees. Then, we introduce a new aggregation algorithm to address summarizability issues in complex hierarchies. On the basis of this algorithm, we propose a novel XOLAP roll-up operator. Finally, we experimentally validate our proposal and compare our approach with the reference approach for addressing summarizability issues in complex hierarchies. For this sake, we extend the XML warehouse benchmark XWeB with complex hierarchies to generate XML data warehouses with scalable complex hierarchies. The results of our experiments show that the overhead induced by managing hierarchy complexity at run-time is totally acceptable and that our approach is expected to scale up well
ARADIAN, Achod André. "Quelques problèmes de dynamique d'interfaces molles". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2001. http://tel.archives-ouvertes.fr/tel-00001386.
Ridouard, Frédéric. "Contributions à des problèmes d'ordonnancement en ligne : l'ordonnancement temps réel de tâches à suspension et l'ordonnancement par une machine à traitement par lot". Poitiers, 2006. http://www.theses.fr/2006POIT2323.
In this report, two scheduling problems are studied, using the competitive analysis. The first problem is the scheduling of independant hard real-time tasks with self-suspensions. We first establish results about the difficulties of this scheduling problem (computationnal complexity, scheduling anomalies and non-optimality of on-line algorithms). We have prooved the non-competitiveness of on-line algorithmes for two performance criteria even if they have a faster processor than the adversary. Finaly, we have studied several feasibility tests established for this problem with the competitive analysis. The second problem concerns the single batching machine scheduling problem. We have proposed three on-line competitive algorithms for problems with unbounded batch sizes. We defined the algorithm αH∞ that is a best possible on-line algorithm for the general problem because its competitive ratio is equal to the lower bound, (1+p5)/2
Bousse, Alexandre. "Problèmes inverses, application à la reconstruction compensée en mouvement en angiographie rotationnelle X". Phd thesis, Université Rennes 1, 2008. http://tel.archives-ouvertes.fr/tel-00361396.
Une fois le mouvement estimé, la reconstruction tomographique à un instant de référence est effectuée par une optimisation aux moindres-carrés qui inclut le mouvement ainsi qu'un terme de pénalité qui favorise les valeurs d'intensités fortes pour les voxels au voisinage de la ligne centrale 3-D, et les faibles valeurs pour les autres. Cette méthode a été testée sur des données simulées basées sur des lignes centrales 3-D préalablement extraites de données MSCT.
Bergé, Pierre. "Algorithmes pour voyager sur un graphe contenant des blocages". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS480.
We study NP-hard problems on graphs with blockages seen as models of networks which are exposed to risk of failures.We treat cut problems via the parameterized complexity framework. The cutset size p is taken as a parameter. Given a set of sources {s1,...,sk} and a target $t, we propose an algorithm which builds a small edge cut of size p separating at least r sources from t. This NP-complete problem is called Partial One-Target Cut. It belongs to the family of multiterminal cut problems. Our algorithm is fixed-parameter tractable (FPT) as its execution takes $2^{O(p^2)}n^{O(1)}$. We prove that the vertex version of this problem, which imposes cuts to contain vertices instead of edges, is W[1]-hard. Then, we design an FPT algorithm which counts the minimum vertex (S,T)-cuts of an undirected graph in time $2^{O(plog p)}n^{O(1)}$.We provide numerous results on the competitive ratio of both deterministic and randomized strategies for the Canadian Traveller Problem. The optimal ratio obtained for the deterministic strategies on general graphs is 2k+1, where k is a given upper bound on the number of blockages. We show that randomized strategies which do not use memory cannot improve the bound 2k+1. In addition, we discuss the tightness of lower bounds on the competitiveness of randomized strategies. The distance competitive ratio for a group of travellers possibly equipped with telecommunication devices is studied. Eventually, a strategy dedicated to equal-weight chordal graphs is proposed while another one is built for graphs with small maximum (s,t)-cuts. Both strategies outperform the ratio 2k+1
Arres, Billel. "Optimisation des performances dans les entrepôts distribués avec Mapreduce : traitement des problèmes de partionnement et de distribution des données". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE2012.
In this manuscript, we addressed the problems of data partitioning and distribution for large scale data warehouses distributed with MapReduce. First, we address the problem of data distribution. In this case, we propose a strategy to optimize data placement on distributed systems, based on the collocation principle. The objective is to optimize queries performances through the definition of an intentional data distribution schema of data to reduce the amount of data transferred between nodes during treatments, specifically during MapReduce’s shuffling phase. Secondly, we propose a new approach to improve data partitioning and placement in distributed file systems, especially Hadoop-based systems, which is the standard implementation of the MapReduce paradigm. The aim is to overcome the default data partitioning and placement policies which does not take any relational data characteristics into account. Our proposal proceeds according to two steps. Based on queries workload, it defines an efficient partitioning schema. After that, the system defines a data distribution schema that meets the best user’s needs, and this, by collocating data blocks on the same or closest nodes. The objective in this case is to optimize queries execution and parallel processing performances, by improving data access. Our third proposal addresses the problem of the workload dynamicity, since users analytical needs evolve through time. In this case, we propose the use of multi-agents systems (MAS) as an extension of our data partitioning and placement approach. Through autonomy and self-control that characterize MAS, we developed a platform that defines automatically new distribution schemas, as new queries appends to the system, and apply a data rebalancing according to this new schema. This allows offloading the system administrator of the burden of managing load balance, besides improving queries performances by adopting careful data partitioning and placement policies. Finally, to validate our contributions we conduct a set of experiments to evaluate our different approaches proposed in this manuscript. We study the impact of an intentional data partitioning and distribution on data warehouse loading phase, the execution of analytical queries, OLAP cubes construction, as well as load balancing. We also defined a cost model that allowed us to evaluate and validate the partitioning strategy proposed in this work
Vu, Dong Quan. "Models and solutions of strategic resource allocation problems : approximate equilibrium and online learning in Blotto games". Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS120.pdf.
Resource allocation problems are broadly defined as situations involving decisions on distributing a limited budget of resources in order to optimize an objective. In particular, many of them involve interactions between competitive decision-makers which can be well captured by game-theoretic models. In this thesis, we choose to investigate resource allocation games. We primarily focus on the Colonel Blotto game (CB game). In the CB game, two competitive players, each having a fixed budget of resources, simultaneously distribute their resources toward n battlefields. Each player evaluates each battlefield with a certain value. In each battlefield, the player who has the higher allocation wins and gains the corresponding value while the other loses and gains zero. Each player's payoff is her aggregate gains from all the battlefields. First, we model several prominent variants of the CB game and their extensions as one-shot complete-information games and analyze players' strategic behaviors. Our first main contribution is a class of approximate (Nash) equilibria in these games for which we prove that the approximation error can be well-controlled. Second, we model resource allocation games with combinatorial structures as online learning problems to study situations involving sequential plays and incomplete information. We make a connection between these games and online shortest path problems (OSP). Our second main contribution is a set of novel regret-minimization algorithms for generic instances of OSP under several restricted feedback settings that provide significant improvements in regret guarantees and running time in comparison with existing solutions
Mazet, Vincent. "Développement de méthodes de traitement de signaux spectroscopiques : estimation de la ligne de base et du spectre de raies". Phd thesis, Université Henri Poincaré - Nancy I, 2005. http://tel.archives-ouvertes.fr/tel-00011477.
Dans un premier temps est proposée une méthode déterministe qui permet d'estimer la ligne de base des spectres par le polynôme qui minimise une fonction-coût non quadratique (fonction de Huber ou parabole tronquée). En particulier, les versions asymétriques sont particulièrement bien adaptées pour les spectres dont les raies sont positives. Pour la minimisation, on utilise l'algorithme de minimisation semi-quadratique LEGEND.
Dans un deuxième temps, on souhaite estimer le spectre de raies : l'approche bayésienne couplée aux techniques MCMC fournit un cadre d'étude très efficace. Une première approche formalise le problème en tant que déconvolution impulsionnelle myope non supervisée. En particulier, le signal impulsionnel est modélisé par un processus Bernoulli-gaussien à support positif ; un algorithme d'acceptation-rejet mixte permet la simulation de lois normales tronquées. Une alternative intéressante à cette approche est de considérer le problème comme une décomposition en motifs élémentaires. Un modèle original est alors introduit ; il a l'intérêt de conserver l'ordre du système fixe. Le problème de permutation d'indices est également étudié et un algorithme de ré-indexage est proposé.
Les algorithmes sont validés sur des spectres simulés puis sur des spectres infrarouge et Raman réels.
Kovalev, Sergey. "PROBLÈMES COMBINATOIRES EN CONFIGURATION DES LIGNES DE FABRICATION : ANALYSE DE COMPLEXITÉ ET OPTIMISATION". Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00849179.
Le, Floc'h Laurence. "Cristaux électromagnétiques bidimensionnels discrets de taille finie : une étude théorique et expérimentale". Brest, 2005. http://www.theses.fr/2005BRES2022.
This thesis is devoted to the theoretical study and development of a novel class of Photonic Crystals (PCs) so-called Discrete Photonic Crystals (DPCs). DPCs are arrangements of multi-port networks interconnected by wave guides. Easily manufactured in the microwave domain, CPDs can be described exactly using a classical linear algebra. After a general introduction on several types of PC, an original study on one-dimensional PCs (1D PCs) is proposed. By considering these PCs as two-port networks, we develop a process of normalization. This tool allows us to perform a universal parametric study of the responses (scattering parameters). The theory is experimentally illustrated with a microstrip periodic transmission line. The concept is then extended to the 2D-type DPCs. Symmetries have been exploited to give the responses of the structure in analytical form and in normalised units. We propose an analysis of PC spectra behaviour by means of a reduced set of parameters whatever the characteristics of the waves. Special care has been with respect to the control of width frequency position and reflectivity of the Photonic Band-gap. A simple and fast design method applied to these “2D”-type DPC has been developed. Low-cost ring-shaped prototypes are fabricated using microstrip technology in the 0-7 GHz band. We finally conduct a theroretical and an experimental study on the effects of boundary conditions on 2D DPCs responses. The optimization of theses conditions enables us to envisage specific functions for applications such as filtering or switching devices
Dardé, Jérémi. "Méthodes de quasi-réversibilité et de lignes de niveau appliquées aux problèmes inverses elliptiques". Phd thesis, Université Paris-Diderot - Paris VII, 2010. http://tel.archives-ouvertes.fr/tel-00551853.
Schroeder, Pascal. "Performance guaranteeing algorithms for solving online decision problems in financial systems". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0143.
This thesis contains several online financial decision problems and their solutions. The problems are formulated as online problems (OP) and online algorithms (OA) are created to solve them. Due to the fact that there can be various OA for the same OP, there must be some criteria with which one can make statements about the quality of an OA. In this thesis these criteria are the competitive ratio (c), the competitive difference (cd) and the numerical performance. An OA with a lower c is preferable to another one with a higher value. An OA that has the lowest c is called optimal. We consider the following OPS. The online conversion problem (OCP), the online portfolio selection problem (PSP) and the cash management problem (CMP). After the introductory chapter, the OPs, the notation and the state of the art in the field of OPs is presented. In the third chapter, three variants of the OCP with interrelated prices are solved. In the fourth chapter the time series search with interrelated prices is revisited and new algorithms are created. At the end of the chapter, the optimal OA k-DIV for the general k-max search with interrelated prices is developed. In Chapter 5 the PSP with interrelated prices is solved. The created OA OPIP is optimal. Using the idea of OPIP, an optimal OA for the two-way trading is created (OCIP). Having OCIP, an optimal OA for the bi-directional search knowing the values of θ_1 and θ_2 is created (BUND). For unknown θ_1 and θ_2, the optimal OA RUNis created. The chapter ends with an empirical (for OPIP) and experimental (for OCIP, BUND and RUN) testing. Chapters 6 and 7 deal with the CMP. In both of them, a numerical testing is done in order to compare the numerical performance of the new OAs to the one of the already established ones. In Chapter 6 an optimal OA is constructed; in Chapter 7, OAs are designed which minimize cd. The OA BCSID solves the CMP with interrelated demands to optimality. The OA aBBCSID solves the CMP when the values of de θ_1, θ_2,m and M are known; however, this OA is not optimal. In Chapter 7 the CMP is solved, knowing m and M and minimizing cd (OA MRBD). For the interrelated demands, a heuristic OA (HMRID) and a cd-minimizing OA (MRID) is presented. HMRID is good compromise between the numerical performance and the minimization of cd. The thesis concludes with a short discussion about shortcomings of the considered OPs and the created OAs. Then some remarks about future research possibilities in this field are given
Boutevin, Corinne. "Problèmes d'ordonnancement et d'affectation avec contraintes de ressources de type RCPSP et line balancing". Clermont-Ferrand 2, 2003. http://www.theses.fr/2003CLF21464.
Valicov, Petru. "Problèmes de placement, de coloration et d’identification". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14549/document.
In this thesis we study three theoretical computer science problems, namely the orthogonal packing problem (OPP for short), strong edge-colouring and identifying codes.OPP consists in testing whether a set of rectangular items can be packed in a rectangular container without overlapping and without exceeding the borders of this container. An additional constraint is that the rotation of the items is not allowed. The problem is NP-hard even when the problem is reduced to packing squares in a square. We propose an exact algorithm for solving OPP efficiently using the characterization of the problem by interval graphs proposed by Fekete and Schepers. For this purpose we use some compact representation of interval graphs - MPQ-trees. We show experimental results of our approach by comparing them to the results of other algorithms known in the literature. we observe promising gains.The study of strong edge-colouring and identifying codes is focused on the structural and computational aspects of these combinatorial problems. In the case of strong edge-colouring we are interested in the families of planar graphs and subcubic graphs. We show optimal upper bounds for the strong chromatic index of subcubic graphs as a function of the maximum average degree. We also show that every planar subcubic graph without induced cycles of length 4 and 5 can be strong edge-coloured with at most nine colours. Finally, we confirm the difficulty of the problem by showing that it remains NP-complete even in some restricted classes of planar subcubic graphs.For the subject of identifying codes we propose a characterization of non-trivial graphs having maximum identifying code number ID, that is n-1, where n is the number of vertices. We study the case of line graphs and prove lower and upper bounds for ID parameter in this class. At last we investigate the complexity of the corresponding decision problem and show the existence of a linear algorithm for computing ID of the line graph L(G) where G has the size of the tree-width bounded by a constant. On the other hand, we show that the identifying code problem is NP-complete in various subclasses of planar graphs
Wazzan-Zrek, Nahla. "Contribution à la résolution des problèmes aux limites en milieux anistoropes par la méthode des lignes bicaractéristiques". Grenoble 1, 1990. http://www.theses.fr/1990GRE10042.
Privault, Caroline. "Modèles mathématiques pour la gestion off-line et on-line des changements d'outils sur une machine flexible". Phd thesis, Grenoble 1, 1994. http://tel.archives-ouvertes.fr/tel-00344527.
Bafounta-Mampouya, Eléazar. "Le problème de la transition en Europe de l'Est : grandes lignes et orientations d'une réforme". Lyon 3, 1999. http://www.theses.fr/1999LYO31011.
Mazoyer, Jacques. "Une solution en temps minimal et à 6 états internes au problème de la synchronisation d'une ligne de fusiliers". Lyon 1, 1986. http://www.theses.fr/1986LYO10062.
Srour, Ali. "Etudes de deux approches mathématiques complémentaires pour un problème de reconstruction tomographique". Thesis, Tours, 2008. http://www.theses.fr/2008TOUR4016/document.
The thesis at hand is composed of four parts. The first of which is devoted to present our model of tomographic reconstruction. The second part treats a non-differentiable variational problem with a non-convex constraint the interior of which is empty for usual topologies. A numerical study of the above approach is elaborated in the third part. A numerical scheme is derived based upon our optimal system, the method of Uzawa and a gradient descent method. In the last part, we use a level-set approach to solve the front propagation problem. A second order Hamilton-Jacobi type equation with a non-local term comes into play. We prove the existence and uniqueness of a viscosity solution in both compact and non-compact fronts cases
Naudin, Edith. "Problèmes de tournées de véhicules avec contraintes de ressources : modélisations par arcs-états et techniques de résolution adaptées". Paris 6, 2003. http://www.theses.fr/2003VERS0038.
Hadj-Amar, Hassiba. "Identification de lignes de courant principales d'un écoulement de fluide par assimilation de données". Paris, CNAM, 2003. http://www.theses.fr/2003CNAM0476.
We present an original method which combines data assimilation and optimal shape design to identify principal streamlines of a fluid flow around a profile, particularly, the boundary streamline between the irrotational incompressible flow and the rotational wake. We can take observations in the area where the flow is irrotational incompressible. We consider a potential flow model. To solve the flow equations, we use an integral equations method. It allows us to solve integral equations on the boundary of a domain instead of solving an exterior problem in a domain. Using the integral equations also allows us to get a boundary mesh in the place of a surface mesh, so we avoid remeshing problem that we have with finite element methods. We minimize a quadratic gap between the observations field and the numerical values obtained by the model. The minimization parameter is the streamline we want to identify. We did the some applications with data simulated by a Navier-Stokes code. The Navier-Stokes solution is the nearest solution to a real flow
Stephan, Yann. "Calcul numérique de solutions discontinues du problème de Hencky en théorie de la plasticité parfaite". Paris 11, 1987. http://www.theses.fr/1987PA112416.
The strain of a solid body submitted to stresses may be described by the displacements field in each point. If we consider field, which is and,a priori, discontinuities a perfectly plastic material, we search a displacements a solution of a non-linear problem (the Hencky's problem) exhibits a loss of regularity: the existence of such is otherwise confirmed by many experimental results (slip surfaces, angles,). If we suppose that the solutions are smooth on both sides of a curve whose exact location remains to be determined, we are led to an Optimal Design problem which we can solve by convex analysis and numerical methods after a well-suited discretization of the functional spaces (by finite elements) and the slip line (by B-Splines. )
Tran, Thi Thanh Mai. "Modélisation des problèmes bi-fluides par la méthode des lignes de niveau et l'adaptation du maillage : Application à l'optimisation des formes". Thesis, Paris 6, 2015. http://www.theses.fr/2014PA066421/document.
The first concern of this thesis is the problem of two fluids flow or two-phase flow, i.e weare interested in the simulation of the evolution of an interface (or a free surface) between twoimmiscible viscous fluids or two phases of a fluid. We propose a general scheme for solving two fluids flow or two-phase flow which takes advantage of the flexibility of the level set method for capturing evolution of the interfaces, including topological changes. Unlike similar approaches that solve the flow problem and the transport equation related to the evolution of the interface on Cartesian grids, our approach relies on an adaptive unstructured mesh to carry out these computations and enjoys an exact and accurate description of the interface. The explicit representation of the manifold separating the two fluids will be extracted to compute approximately the surface tension as well as some algebraic quantities like the normal vector and the curvature at the interface.In a nutshell, the resolution of a two-fluid problem is summarized by the steps involves thefollowing ingredients:– solving incompressible Navier-Stokes equations by the first order Lagrange-Galerkin method;– geometrical treatment to evaluate the surface tension basing on the explicit discretisation of the interface;– solving the level set advection by method of characteristics; – the techniques of mesh adaptation.It is obvious that no numerical method is completely exact in solving the PDE problemat hand, hence, we need a discretized computational domain. However, the accuracy of numericalsolutions or the mass loss/gain can generally be improved with mesh refinement. The question thatarises is related to where and how to refine the mesh. At each time, our mesh adaptation producesthe adapted mesh based on the geometric properties of the interface and the physical properties ofthe fluid, simply speaking, only one adapted mesh at each time step to assume both the resolutionof Navier-Stokes and the advection equations. It answers to the need for an accurate representationof the interface and an accurate approximation of the velocity of fluids with a minimal number ofelements, then decreasing the amount of computational time. Some results of the classical examples for both problems of monofluid and bifluid flows as : lid-driven cavity, rising bubble, coalescence of two bubbles, and Rayleigh-Taylor instability are investigated in two and three dimensions.The second part of this thesis is related to shape optimization in fluid mechanics. We construct a numerical scheme using level set method and mesh adaptation in the context of Stokes systems. The computation of the sensitivity of objective function is related to the Hadamard’s boundary variation method and the shape derivatives is computed by Céa’s formal method. A numerical example with theobjective function of energy dissipation is presented to assess the efficiency and the reliability of theproposed scheme
Abdous, Mohammed Amine. "Optimal design of manufacturing systems with ergonomics : application to assembly lines". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEM034.
This thesis contributes to the research stream of evaluation and optimization of ergonomics in the design phase of manufacturing systems. Poor physical ergonomics in manufacturing systems results in lower productivity, lower motivation, injuries, and increases costs for companies. The main objective of this work is the proposition of optimization methods for manufacturing systems design, with the joint consideration of ergonomics, productivity, and cost. This work focuses on the preliminary design of assembly lines. The challenge is to provide decision-makers with optimization methods to take ergonomics into account while satisfying all technological and economic constraints. The combinatorial problems considered are the assembly line balancing problem and the selection of equipment. We considered a quantitative model of ergonomics based on fatigue and recovery equations taken from the literature. In addition to the combinatorial nature of problems dealt with, the main scientific challenge stems from the non-linear nature of the ergonomics model. We proposed a linearization allowing defining an integer linear program, we developed optimal and approximate resolution approaches. Besides, we proposed a generalization of the approach, with a multi-objective model optimizing cost and ergonomics. We developed a multi-objective algorithm for its resolution.Based on the proposed models and optimization algorithms, we have defined a methodology for the design of assembly lines with the optimization of ergonomics from the design phase. This methodology has been successfully applied to industrial cases
Lapointe, Alexandra. "Optimisation de la régularité du service de transport en commun dans le but d'éviter le groupage d'autobus au Réseau de transport de la Capitale". Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/36679.
The regularity optimization project of the public transit service aims at finding solutions to the bus bunching problem at the Réseau de Transport de la Capitale. The phenomenon is characterized by irregular intervals between the transits of buses at stops. The delays incurred by certain buses are at the origin of the problem. Delays are caused by sporadic events that are influenced by the physical and temporal characteristics of a bus line. This research focuses on the Métrobus 807, a crowded bus route that travels the axis between the West and East poles of Quebec City. The goal is to suggest solutions to the problem and to compare them with each other in order to make the proper recommendations for a potential implementation. Currently, irregular intervals, consequences of the bus bunching phenomenon, are noted in several places on the network as well as on the 807 bus route. The efficiency of the network as well as the public transit user experience in Quebec City is negatively affected. The suggested solutions in the present research include solutions applied individually as well as combined with others. The suggested solutions act on the potential sources of delays and are meant to quickly restore the intervals following the detection of a bus bunching event. The solutions are then tested under a discrete event simulation to predict their performance under real circumstances. The simulation allows to test the solutions in a dynamic environment in which it is possible to quantify and qualify the expected results prior to an implementation. The recommendations made in this research allow to improve the regularity of the public transit service, to maximize the use of resources and to offer to the public transit user a comfortable and enhanced experience.
Leman, Samuel. "Contribution à la résolution de problèmes de compatibilité électromagnétique par le formalisme des circuits électriques de Kron". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10147/document.
Analysis of the Electromagnetic Compatibility (EMC) of so-called complex systems consists of predicting voltage induced on electronic circuits submitted to various EM couplings. Such phenomena may consist of couplings between EM and Thermal parameters, or they may concern couplings throughout systems of various sizes with respect to the wavelength and the behaviour of the system. These interactions may also depend on many parameters like dimension, physical data and so on. This thesis is aimed at developing a method well-suited to resolving the problems posed by the EMC of complex systems. This method reduces these couplings to a circuit assembly with a combination of inductance, capacitance and resistance, voltage source and current source. The main advantage of the methodology will be to use the formalism of electrical networks developed by G. KRON, which consists of solving the circuit theory by means of the inversion of a large matrix size. In the scope of this work, EM coupling between cables, shielded cables, antennas, and an EM cavity were simulated with KRON’s formalism to establish a library of subroutines to use to solve complex EMC problems. The comparison between KRON’s method and measurements of the coupling between antennas inside an EM cavity under various configurations shows the efficiency of the method for EMC problems concerning systems of variable sizes and large numbers of parameters. Finally, we proposed to study the simulation of an electrothermal system which consists of both the electrical propagation and thermal diffusion inside a coaxial system filled with a thermally and electrically conducing material. This study seems to open new possibilities for the development of a new generation of EMC tool
Djaziri, Leila. "Diagnostic de défauts d'isolement dans des lignes de transmission électriques : application aux cables de signalisation SNCF". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112134/document.
This thesis work focuses on the detection of insulation faults in very long transmission lines. This is detecting soft defects related to the insulation between the conductors of a long cable which are represented by the leakage conductance parameter. Detect these faults, signs of a possible future short-circuit, is an important issue but requires a noninvasive method. For example, in the case of railway signaling cables, it is to develop a method of diagnosis of very low leakage conductances in signaling cables along railways compatible with the movement of trains. Be aware estimate from measurements in one point of the cable, strong resistance distributed over several hundred meters without disturbing the continuous frequency range to 40 kHz, reserved for service signals. Indeed, the signal cables from the train that interest us have an average length 1500 m and are used in the frequency band 0-40 kHz.We propose so a frequency method for estimating low defects to medium frequency in uniform transmission lines with losses. It is based on two main ideas : a detailed analysis of joint effects of dissipation and dispersion and a method of comparing two lines having the same characteristics and differing only leak conductance parameter. This method of comparison was widespread in the case of multiconductor lines by adopting a statistical approach.This thesis has brought new results : losses estimation formulas resulting from the detailed analysis of a share of joint effects of dissipation and dispersion and also the method of comparing two lines. Numerical simulations were made in both cases to validate the proposed frequency method. Experiments were performed to validate the statistical analysis in the case of multiconductor lines
Visco, Comandini Filippo. "Some inverse cattering problems on star-shapped graphs : application to fault detection on electrical transmission line networks". Versailles-St Quentin en Yvelines, 2011. http://www.theses.fr/2011VERS0035.
In this thesis, having in mind applications to the fault-detection/diagnosis of electrical networks, we consider some inverse scattering problems for the Zakharov-Shabat equations and time-independent Schrödinger operators over star-shaped graphs. The first chapter is devoted to describe reflectometry methods applied to electrical networks as an inverse scattering problems on the star-shaped graphs. Modeled by the telegrapher’s equations, reflectometry experiments can be written as inverse scattering problems for Schrödinger operator in the lossless case and for Zakharov-Shabat system for the lossy transmission network. In Chapter 2 we introduce some elements of the inverse scattering theory for 1 d Schrödinger equations and the Zakharov-Shabat system. We recall the basic results for these two systems and we present the state of art of scattering theory on network. The third chapter deals with some inverse scattering for the Schrödinger operators. We prove the identifiability of the geometry of the star-shaped graph: the number of the edges and their length. Next, we study the potential identification problem by inverse scattering. In the last chapter we focus on the inverse scattering problems for lossy transmission star-shaped network. We prove the identifiability of some geometric informations by inverse scattering and we present a result toward the identification of the heterogeneities, showing the identifiability of the loss line factor
Batog, Guillaume. "Problèmes classiques en vision par ordinateur et en géométrie algorithmique revisités via la géométrie des droites". Phd thesis, Université Nancy II, 2011. http://tel.archives-ouvertes.fr/tel-00653043.
Ghnatios, Chady. "Simulation avancée des problèmes thermiques rencontrés lors de la mise en forme des composites". Phd thesis, Ecole centrale de Nantes, 2012. http://tel.archives-ouvertes.fr/tel-00867281.
Bouland, Catherine. "Etude morphologique et expérimentale de l'appareil reproducteur d'Asterias rubens L.(Echinodermata-Asteroidea). Contrôle du cycle gonadique annuel et problème de la lignée germinale". Doctoral thesis, Universite Libre de Bruxelles, 1987. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213482.
Pillain, Axelle. "Line, Surface, and Volume Integral Equations for the Electromagnetic Modelling of the Electroencephalography Forward Problem". Thesis, Télécom Bretagne, 2016. http://www.theses.fr/2016TELB0412/document.
Electroencephalography (EEG) is a very useful tool for characterizing epileptic sources. Brain source imaging with EEG necessitates to solve the so-called EEG inverse problem. Its solution depends on the solution of the EEG forward problem that provides from known current sources the potential measured at the electrodes positions. For realistic head shapes, this problem can be solved with different numerical techniques. In particular surface integral equations necessitates to discretize only the interfaces between the brain compartments. However, the existing formulations do not take into account the anisotropy of the media. The work presented in this thesis introduces two new integral formulations to tackle this weakness. An indirect formulation that can handle brain anisotropies is proposed. It is discretized with basis functions conform to the mapping properties of the involved operators. The effect of this mixed discretization on brain source reconstruction is also studied. The second formulation focuses on the white matter fiber anisotropy. Obtaining the solution to the obtained numerical system rapidly is also highly desirable. The work is hence complemented with a proof of the preconditioning effect of Calderon strategies for multilayered media. The proposed theorem is applied in the context of solving the EEG forward problem. A Calderon preconditioner is also introduced for the wire electric field integral equation. Finally, preliminary results on the impact of a fast direct solver in solving the EEG forward problem are presented
Lei, Ming. "Imagerie 3D d'impédance bioélectrique : problème direct, problème inverse : détermination des lignes de courant en 3D et application de la méthode de la matrice de sensibilité pour la reconstruction d'une image en 3D dans un volume conducteur inhomogène sphérique". Toulouse, INPT, 1995. http://www.theses.fr/1995INPT010H.
Moultaka, Jihane. "Synthèse des populations stellaires dans les galaxies proches : aspect théorique et applications". Paris 6, 2001. http://www.theses.fr/2001PA066463.
Gardeux, Vincent. "Conception d'heuristiques d'optimisation pour les problèmes de grande dimension : application à l'analyse de données de puces à ADN". Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00676449.
Batog, Guillaume. "Problèmes classiques en vision par ordinateur et en géométrie algorithmique revisités via la géométrie des droites". Electronic Thesis or Diss., Nancy 2, 2011. http://www.theses.fr/2011NAN23001.
Systematize is the leitmotiv of the results in this thesis. Three problems are studied in the field of computer vision and computational geometry. In the first one, we extend all the machinery of the pinhole model for classical cameras to a whole set of cameras (two-slit, pushbroom, oblique, pencil), which were separately studied with different approaches. In the second one, we generalize to convex bodies in R3 the work on pinning lines by or balls, which had so far been tackled by techniques intimately linked to the geometry of the objects. In the third one, we attempt to work out a systematic approach in place of problem-specific methods in order to build polynomial evaluation trees for geometric predicates. Such goals could not be reached without a mathematical investigation in the study of linear line congruences, differential properties of sets of tangent lines to a convex and classical invariant theory respectively. These tools or their uses are mostly based on line geometry in P3 (R). This geometry was designed in the second half of the 19th century but its full power hos not yet been used by the computational geometry community. This thesis therefore also serves as an extended tutorial
Wegener, Jan-Thierry. "Redeployment in Convoys of Fleets of Shared Vehicles". Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22722/document.
Carsharing is a modern way of car rental, attractive to customers who make only occasional use of a car on demand. In a carsharing system, a fleet of cars is distributed at specified stations in an urban area, customers can take a car at any time and station and return it at any time and station, provided that there is a car available at the start station and a free place at the destination station. To ensure the latter, customers have to book their demands in advance. For operating such a system in a satisfactory way, the stations have to keep a good ratio between the total number of places and the number of cars in each station, in order to serve as many requests as possible. This leads to the problem of balancing the load of the stations, called Relocation Problem: an operator has to monitor the load and to decide when and how to move cars from “overfull” stations to “underfull” ones. We consider an innovative carsharing system, where the cars are partly autonomous, which allows to build wireless convoys of cars leaded by a special vehicle, such that the whole convoy is moved by only one driver. This setting is similar to bikesharing, where trucks can simultaneously move several bikes during the relocation process. In this thesis, we address the dynamic and static aspects of the Relocation Problem. The “Dynamic Relocation Problem” describes the situation when cars can be moved between stations during the working hours in order to satisfy the needs of the customers. Hereby, the operator has to make decisions dynamically according to the current situation. In the “Static Relocation Problem” we assume that there is no (or only little) interaction by customers with the system. This situation occurs when the carsharing system is prepared for the next day, i.e., the relocation process is performed during the night. We model the Relocation Problem in the framework of a metric task system. Afterwards, we theoretically analyze both problems and give strategies to solve them. Finally, we perform some computational experiments to examine the applicability of the presented algorithms in practice
Khouadjia, Mostepha Redouane. "Solving dynamic vehicle routing problems : from single-solution based metaheuristics to parallel population based metaheuristics". Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10140/document.
Many problems in the real world have dynamic nature and can be modeled as dynamic combinatorial optimization problems. However, research on dynamic optimization focuses on continuous optimization problems, and rarely targets combinatorial problems. One of the applications in dynamic combinatorial problems that has received a growing interest during the last decades is the on-line or dynamic transportation systems. A typical problem of this domain is the Dynamic Vehicle Routing Problems (DVRPs). In this latter, the dynamism can be attributed to several factors (weather condition, new customer order, cancellation of old demand, vehicle broken down, etc.). In such application, information on the problem is not completely known a priori, but instead is revealed to the decision maker progressively with time. Consequently, solutions for different instances have to be found as time proceeds, concurrently with managing the incoming information. Such problems call for a methodology to track their optimal solutions through time. In this thesis, dynamic vehicle routing problem is addressed and developing general methodologies called metaheuristics to tackle this problem is investigated. Their ability to adapt to the changing environment and their robustness are discussed. Results of experiments demonstrate thanks to dynamic performance measures that our methods are effective on this problem and hence have a great potential for other dynamic combinatorial problems
Brethomé, Lucile. "Modélisation et optimisation d’un plan de transport ferroviaire en zone dense du point de vue des voyageurs". Thesis, Ecole centrale de Lille, 2018. http://www.theses.fr/2018ECLI0014.
The design of a railway transportation plan is a process achieved between two years and six months before it is put into service. The main phases in the design of a transportation plan are the line planning, the timetabling, the rolling stock and the crew scheduling.The design of the transportation plan can have many consequences on the quality of service: an inadequate frequency in station can cause a loss of passengers, sufficient number of seated places, robustness of the timetable in the face of small incidents... In dense area, as in the Ile-de-France region, all these elements must be taken into account as the transportation plan is designed.Today, SNCF Transilien designs its transportation plans by first taking into account the optimization of production resources (train paths, rolling stock units and drivers). However, today, the increase in resources implemented no longer improves the adequacy of the transportation plan to passengers’ demand. This design method no longer makes it possible to cope with the increase in the demand for mobility (+3% each year since 2000). This is why we must rethink the design of the transport plan by immediately integrating the passenger dimension. Our work focuses on issues of line planning and timetabling in a passenger-oriented approach. First, we present a multi-objective model for line planning. Then, we present a model of timetabling incorporating passenger route choice. Then, we initiate a method to integrate these two models. Finally, we present an evaluation of our results thanks to reliability indicators from the literature and a macroscopic simulation of the timetables
Cozza, Andrea. "Railways EMC : Assessment of Infrastructure Impact". Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2005. http://tel.archives-ouvertes.fr/tel-00533672.
Adous, Mourad. "Caractérisation électromagnétique des métariaux traités de génie civil dans la bande de fréquence 50 MHz - 13 GHz". Phd thesis, Université de Nantes, 2006. http://tel.archives-ouvertes.fr/tel-00110739.
Outre leurs caractères large bande et peu destructif, des simulations numériques réalisées à l'aide d'un logiciel électromagnétique 3D ont montré que ces techniques présentent les avantages d'avoir une grande profondeur de pénétration (supérieure à 6 cm), ainsi qu'une bonne sensibilité de mesure. Elles permettent alors de satisfaire le critère du Volume Élémentaire Représentatif (VER - taille minimale du matériau pour avoir des mesures représentatives).
L'étude théorique des sondes/cellule a nécessité l'analyse des problèmes direct et inverse. L'étude du problème direct permet de calculer le coefficient de réflexion en fonction des propriétés diélectriques du matériau à caractériser. Le calcul de la permittivité à partir du coefficient de réflexion mesuré définit le problème inverse. Après la conception des dispositifs de mesure, les logiciels de dépouillement des données et d'étalonnage ont été validés sur des matériaux étalons.
Enfin, Les mesures réalisées sur différents mélanges de béton ont montré que la nature des granulats joue un rôle prépondérant sur la variation de la permittivité, que la taille maximale des granulats influence la permittivité dans le domaine centimétrique, et que cette dernière varie linéairement en fonction de la compacité.
Teiller, Alexandre. "Aspects algorithmiques de l'optimisation « multistage »". Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS471.
N a classical combinatorial optimization setting, given an instance of a problem one needs to find a good feasible solution. However, in many situations, the data may evolve over time and one has to solve a sequence of instances. Gupta et al. (2014) and Eisenstat et al. (2014) proposed a multistage model where given a time horizon the input is a sequence of instances (one for each time step), and the goal is to find a sequence of solutions (one for each time step) reaching a trade-off between the quality of the solutions in each time step and the stability/similarity of the solutions in consecutive time steps. In Chapter 1 of the thesis, we will present an overview of optimization problems tackling evolving data. Then, in Chapter 2, the multistage knapsack problem is addressed in the offline setting. The main contribution is a polynomial time approximation scheme (PTAS) for the problem in the offline setting. In Chapter 3, the multistage framework is studied for multistage problems in the online setting. The main contribution of this chapter was the introduction of a structure for these problems and almost tight upper and lower bounds on the best-possible competitive ratio for these models. Finally in chapter 4 is presented a direct application of the multistage framework in a musical context i.e. the target-based computed-assisted orchestration problem. Is presented a theoretical analysis of the problem, with NP-hardness and approximation results as well as some experimentations
Chantalat, Frédéric. "Méthodes level-set et de pénalisation pour l'optimisation et le contrôle d'écoulements". Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13828/document.
This work deals with e?cient numerical solving of problems linked with shape optimization or ?ow control. The combination between penalization, that allows to impose boundary conditions while avoiding the use of body-?tted grids, and Level-Set methods, which enable a natural non-parametric representation of the geometries to be optimized, is implemented. In the ?rst part, a model inverse problem, and an application pertaining to optimal design in Stokes ?ows, are treated with an iterative algorithm. Special care is devoted to the solution of the PDE’s in the vicinity of the penalized regions. The discretization accuracy is increased. Various gradient preconditionings aiming at improving the convergence are also discussed. The second part is dedicated to direct numerical simulation of ?ows in the neighborhood of an actuator, in the context of active control by pulsed jets used on the Ahmed body. The local study emphasizes the in?uence of various parameters on the action quality, in particular the pulsation frequency, or the aspect of exit velocity pro?les. As a synthesis, shape optimization is performed on the actuator of chapter two, thanks to the previously introduced coupling between Level-Set and penalization. The framework is simpli?ed and topological constraints are imposed. The inverse problem we set intends to modify the MEMS inner geometry to retrieve a given jet pro?le on the exit section
Davidoiu, Valentina. "Approches non linéaire en imagerie de phase par rayons X dans le domaine de Fresnel". Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00952854.
Ion, Valentina. "Nonlinear approaches for phase retrieval in the Fresnel region for hard X-ray imaging". Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-01015814.
Ibn, Taarit Kaouther. "Contribution à l'identification des systèmes à retards et d'une classe de systèmes hybrides". Phd thesis, Ecole Centrale de Lille, 2010. http://tel.archives-ouvertes.fr/tel-00587336.