Дисертації з теми "Optimisation efficace"
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Hamdar, Marian. "Conception et optimisation d'un système indirect efficace de climatisation ferroviaire." Paris, ENMP, 2008. http://www.theses.fr/2008ENMP1693.
Davot, Tom. "A la recherche de l’échafaudage parfait : efficace, de qualité et garanti." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS030.
Sequencing is a process in biology that determines the order of nucleotides in the DNA. It produces a set of fragments, called reads, in which the genetic information is known. Unfortunatly, the genomic sequence is decomposed in small pieces. In order to analyse it, it is necessary to reconstruct it using a number of computer processes. In this thesis, we studied two mathematical problems arising from this sequencing: the scaffolding and the linearization.The scaffolding is a process that takes place after the reads assembly into larger subsequences called contigs. It consists in the search of paths and cycles in a particular graph called scaffold graph. These paths and cycles represent the linear and circular chromosomes of the organism whose DNA has been sequenced. The linearization is a problem related to the scaffolding. When we take into account that contigs may appear several times in the genomic sequence, some ambiguities can arise. If this ambiguities are not deleted, then a chimeric sequence may be produced by the scaffolding. To solve this problem, a solution computed by the scaffolding should be wisely deteriorated. In any case, both problems can be modelized as optimization problems in a graph.In this document, we study both problems focusing on three aspects. The first aspect consists in the study of the complexity of these problems. The second aspect consists in the development of algorithms, exact or approximate, to solve these problems. Finally, the last aspect consists in implementing and testing these algorithms to look at their behaviors on real instances
Tap, Samuel. "Construction de nouveaux outils de chiffrement homomorphe efficace." Electronic Thesis or Diss., Université de Rennes (2023-....), 2023. http://www.theses.fr/2023URENS103.
In our everyday life, we leave a trail of data whenever we access online services. Some are given voluntarily and others reluctantly. Those data are collected and analyzed in the clear which leads to major threats on the user's privacy and prevents collaborations between entities working on sensitive data. In this context, Fully Homomorphic Encryption brings a new hope by enabling computation over encrypted data, which removes the need to access data in the clear to analyze and exploit it. This thesis focuses on TFHE, a recent fully homomorphic encryption scheme able to compute a bootstrapping in record time. We introduce an optimization framework to set the degrees of freedom inherent to homomorphic computations which gives non-experts the ability to use it (more) easily. We describe a plethora of new FHE algorithms which improve significantly the state of the art and limit, (if not remove) existing restrictions. Efficient open source implementations are already accessible
Potop-Butucaru, Dumitru. "Optimisations pour la simulation efficace de programmes Esterel." Paris, ENMP, 2002. http://www.theses.fr/2002ENMP0002.
Esterel is a design language for reactive embedded systems. It enjoys a full-fledged formal operational semantics, and can customarily be compiled into either explicit Finite State Machines or Digital Sequential Circuit models, thereby providing implementation codes with very distinctive flavors. While being semantically complete, the model-based techniques do not support the generation of efficient (fast and small) code for large specifications. For this reason, new compilation schemes were proposed for the generation of efficient sequential ( C) code. Consisting essentially in direct actual simulation of the language reactive features, the new approach now needs to be accommodated with similar semantic issues as the previous ones (FSM- and circuit-based). Such issues include dealing with the whole class of constructively causal programs, or performing optimization and analysis of this level. To this end, we propose here a new format/model (named GRC) for the intermediate representation of Esterel programs. The new format has formal constructive semantics, being able to represent all the Esterel programs. It describes with separate (but interdependent) structures the hierarchic state of the Esterel program and its destructured control flow. Thus, it is a good support for both (1) efficient low-cost optimizations based on static analysis that use high-level structural information and (2) low-level control flow optimizations. Finally, the format is a good starting point for efficient scheduling algorithms. Our contribution consists in the following : - The precise definition of the semantics of the full Esterel language ; - The definition of the GRC format (including the formal correspondence between its semantics and the “circuit” semantics) ; - A characterization, at GRC level, of the programs that are translated into cyclic circuits ; - The development of an optimizing GRC-based prototype C code generator. The prototype is currently able to compile the programs whose GRC representation is acyclic. Sequential code is generated in these cases by statically scheduling the acyclic GRC flowgraph. The compiler includes novel optimization algorithms, based on static analysis, and an efficient state encoding technique. The results are encouraging, as our prototype seems to compare well against existing compilers
Hasan, Cengis. "Optimisation de l'allocation de ressources dans les réseaux celluaires : une approche efficace en énergie." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00942967.
Gougeon, Adrien. "Optimisation d’un réseau dynamique et efficace en énergie servant à piloter la grille électrique." Electronic Thesis or Diss., Université de Rennes (2023-....), 2023. https://tel.archives-ouvertes.fr/tel-04086397.
In front of the challenges concerning the energy and environmental sectors, the electrical grid faces some limitations. A major issue of the current power network is the lack of communication and coordination between its actors to fully exploit its potential.To overcome those limitations, and offer new services to the actors of the electrical grid, we are moving toward the Smart Grid. The deployment of an additional infrastructure is necessary to enable the Smart Grid. This infrastructure, known as the Advanced Metering Infrastructure (AMI), aims to enhance the monitoring and communication capabilities of the actors of the electrical grid.The goal of this thesis is to quantify the performance degradation of some new services of the Smart Grid, due to the quality of service of the AMI. We explore several parameters of the communication infrastructure and observe through co-simulation how those parameters influence the efficiency of those services. One of the main objectives of the Smart Grid is to reduce energy consumption.In a second stage, we model the end-to-end energy consumption of an AMI at a large scale to assess its own consumption.The proposed co-simulation framework and consumption models are all license free
Villemonteix, Julien. "Optimisation de fonctions coûteusesModèles gaussiens pour une utilisation efficace du budget d'évaluations : théorie et pratique industrielle." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00351406.
en ingénierie. Comment optimiser une fonction lorsque le nombre d'évaluations autorisé est très limité au regard de la dimension et de la complexité du problème ? Par exemple, lorsque le budget d'évaluations est limité par la durée des simulations numériques du système à optimiser, il n'est pas rare de devoir optimiser trente paramètres avec moins
de cent évaluations. Ce travail traite d'algorithmes d'optimisation spécifiques à ce contexte pour lequel la plupart des méthodes classiques sont inadaptées.
Le principe commun aux méthodes proposées est d'exploiter les propriétés des processus gaussiens et du krigeage pour construire une approximation peu coûteuse de la fonction à optimiser. Cette approximation est ensuite utilisée pour choisir itérativement les évaluations à réaliser. Ce choix est dicté par un critère d'échantillonnage qui combine recherche locale, à proximité des résultats prometteurs, et recherche globale, dans les zones non explorées. La plupart des critères proposés dans la littérature, tel celui de l'algorithme EGO (pour Efficient Global Optimization), cherchent à échantillonner la fonction là où l'apparition d'un optimum est jugée la plus probable. En comparaison, l'algorithme IAGO (pour Informational Approach to Global Optimization), principale contribution de nos travaux, cherche à maximiser la quantité d'information apportée, sur la position de l'optimum, par l'évaluation réalisée. Des problématiques industrielles ont guidé l'organisation de ce mémoire, qui se destine à la communauté de l'optimisation
tout comme aux praticiens confrontés à des fonctions à l'évaluation coûteuse. Aussi les applications industrielles y tiennent-elles une place importante tout comme la mise en place de l'algorithme IAGO. Nous détaillons non seulement le cas standard de l'optimisation d'une fonction réelle, mais aussi la prise en compte de contraintes, de
bruit sur les résultats des évaluations, de résultats d'évaluation du gradient, de problèmes multi-objectifs, ou encore d'incertitudes de fabrication significatives.
Mezmaz, Mohand. "Une approche efficace pour le passage sur grilles de calcul de méthodes d'optimisation combinatoire." Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Mezmaz.pdf.
The exact resolution of large combinatorial optimization problems is a challenge for grids. Indeed, it is necessary to rethink the resolution algorithms to take into account the characteristics of such environments, in particular their large-scale, the heterogeneity and the dynamic availability of their resources, and their multi-domain administration. Ln this thesis, we propose a new approach, called B&B@Grid, to adapt exact methods for grids. This approach is based on coding work units in the form of intervals in order to minimize the cost of communications caused by the operations of load balancing, fault tolerance and detection of termination. This approach, about 100 times more efficient than the best known approach in term of communication cost, led to the optimal resolution on the Grid5000 of a standard instance of the Flow-Shop problem remained unsolved for fifteen years. To accelerate the resolution, we also deal with cooperation on the grid of exact methods with meta-heuristics. Two cooperation modes have been considered: the relay mode where a meta-heuristic is performed before an exact method, and the co-evolutionary mode where both methods are executed in parallel. The implementation of this cooperation on a grid has led us to propose an extension of the Linda coordination model
Griset, Rodolphe. "Méthodes pour la résolution efficace de très grands problèmes combinatoires stochastiques : application à un problème industriel d'EDF." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0219/document.
The purpose of this Ph.D. thesis is to study optimization techniques for large-scale stochastic combinatorial problems. We apply those techniques to the problem of scheduling EDF nuclear power plant maintenance outages, which is of significant importance due to the major part of the nuclear energy in the French electricity system. We build on a two-stages extended formulation, the first level of which fixes nuclear outage dates and production profiles for nuclear plants, while the second evaluates the cost to meet the demand. This formulation enables the solving of deterministic industrial instances to optimality, by using a MIP solver. However, the computational time increases significantly with the number of scenarios. Hence, we resort to a procedure combining column generation of a Dantzig-Wolfe decomposition with Benders’ cut generation, to account for the linear relaxation of stochastic instances. We then obtain integer solutions of good quality via a heuristic, up to fifty scenarios. We further assume that outage durations are uncertain and that unexpected shutdowns of plants may occur. We investigate robust optimization methods in this context while ignoring possible recourse on power plants outage dates. We report on several approaches, which use bi-objective or probabilistic methods, to ensure the satisfaction of constraints which might be relaxed in the operating process. For other constraints, we apply a budget uncertainty-based approach to limit future re-organizations of the scheduling. Adding probabilistic information leads to better control of the price of the robustness
Tran, Khanh Toan. "Déploiement efficace de services complexes dans l'infrastructure de cloud." Phd thesis, Université d'Evry-Val d'Essonne, 2013. http://tel.archives-ouvertes.fr/tel-00875818.
Bouchakhchoukha, Adel. "Modèles de résolution approchée et efficace pour les problèmes des réseaux de transport et de télécommunication." Thesis, Paris 1, 2015. http://www.theses.fr/2015PA010046.
The need to save time as well as minimize effort is part of the human condition and it has driven our though s from antiquity until these last few decades, now characterized by the emergence of a mix in all fields between rapidity of calculation and precision in the result. The vehicle routing problem and its extensions are an important field for theorists of these utilities for real-world applications. Recent research in the field has led to significant advantages in problem formulation and designing algorithm analyses. This study considers logistics problems. A particular locus was given to a certain case of telecommunications networks 2ECONNDPR, as well as the method of intelligently creating designs to ensure vitality and durability in information circulation. Furthermore, the study considered vehicle routing problems, with time windows and orienteering problems from the VRP and OP families, respectively. This is the framework for this thesis. Solutions to these problems use programming techniques known for their calculation speed, i .e ., Beam-search and very large-scale neighborhood searching. First, a detailed study is presented of these above mentioned problems, along with the various types or resolution methods. Next, a very large-scale neighborhood search method is presented, suited to the design of a survivable network with relay, a proposition for a three-stage heuristic for the capacitated vehicle routing problem with time windows and, finally, a proposition for a hybrid heuristic for the team orienteering problem
Mazauric, Dorian. "Optimisation discrète dans les réseaux de télécommunication : reconfiguration du routage, routage efficace en énergie, ordonnancement de liens et placement de données." Phd thesis, Université de Nice Sophia-Antipolis, 2011. http://tel.archives-ouvertes.fr/tel-00643513.
Arexis, Boisson Lydie. "Étude et optimisation d'un système d'éclairage efficace énergétiquement et adapté aux besoins de ses utilisateurs (santé, sécurité et qualité de vie)." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2332/.
Light visual perception is a topic that interrogates since many years. In this research, we focus particularly on visual comfort of Humans subjected to light flickering, which may have significant health impacts. But in order to understand the visual perception of flickering, also known as luminance or chromatic temporal contrast, multiple prerequisites are required. That is why, throughout this research we have a multidisciplinary approach, and make use of knowledge about Humans: physiology of the human eye and its mechanisms of perception, neurophysiology, cognitive psychology, sociology, but also on the physics of light sources, their photometry and colorimetry, geometrical optic and optical modeling concepts, etc. The term "comfort" is often misused, that's why we first thought to accurately define the notions of comfort and distinguish terms "quality of life" and "well being" too often taken to be synonymous. To achieve this, we based our study on a cognitive approach, and oriented it in the particulary case of visual comfort, in relation to our research topic. Then, an experimental campaign on the flickering was conducted. It consisted in phenomenological study of the visual perception of flickering in different contexts: color of the environment, areas of visual perception for different experimental configurations. For this purpose, an experimental and interactive box was created. To generate the flickering, light emitting diodes ( LEDs) have been used, and a control module were used to change the two particular parameters : frequency and duty cycle. We have created a PWM signal, and have made an indirect light stimulus with a wide field. Due to the associated control module, many scenarii of flicker light have been presented to volunteers who have given their felt. The observers were selected with similar visual characteristics (emmetropic vision) and aged between 20 and 39 years. Some studies on ametropic eyes were also started. To further analyze the experimental results, an optimization method was used. It showed optimal solutions couples (frequency and duty cycle) regardless of the color of the environment and whatever axis of visual perception. We then based on these results to develop graphs of physical parameters of flickering visual comfort. Finally, a flickering application study was conducted. It consisted of comparing the color degradation of museums artworks using standard samples lit with LED power supplied with continuous mode comparing to pulse mode, and creating a constant average illumination. The damage proved to be of the same order at the end of 635000 lux. H. But as we could check the Broca Sulzer effect in our experiments (brightness felt is greater than the physical brightness), we could expect energy savings with flickering
Moussa, Ibrahim. "Modèles de résolution approchée et efficace pour les problèmes des réseaux de transport et de télécommunication." Electronic Thesis or Diss., Amiens, 2015. http://www.theses.fr/2015AMIE0009.
This thesis focuses on solving combinatorial optimization problems NP-hard using approximate solving methods. Two practical application areas are targeted here, firstly the general problem of vehicule routing network with a variant specifically with planning tours with a vehicle team, on the other hand the multicast session management problem on a telecommunications network, addressed by the broader perspective of clustering in a bipartite graph. Both applications are obviously of interest both from the fundamental point of view for the resolution methods that must always progress facing new challenges, from the point of view of potential industrial benefits. The resolution of such problems usually has two phases: initially it comes to define one or more mathematical models to compare possibly to choose the most effective according to the available resolution tools; secondly it is possible to use a generic resolution paradigm, such as a linear programming solver, or specialize an algorithm by including specific heuristics and knowledge to optimize its performance. This thesis is in this second approach. This is often necessary when the problems addressed become complex and / or large and that we need to be designing more efficient algorithms
Moussa, Ibrahim. "Modèles de résolution approchée et efficace pour les problèmes des réseaux de transport et de télécommunication." Thesis, Amiens, 2015. http://www.theses.fr/2015AMIE0009/document.
This thesis focuses on solving combinatorial optimization problems NP-hard using approximate solving methods. Two practical application areas are targeted here, firstly the general problem of vehicule routing network with a variant specifically with planning tours with a vehicle team, on the other hand the multicast session management problem on a telecommunications network, addressed by the broader perspective of clustering in a bipartite graph. Both applications are obviously of interest both from the fundamental point of view for the resolution methods that must always progress facing new challenges, from the point of view of potential industrial benefits. The resolution of such problems usually has two phases: initially it comes to define one or more mathematical models to compare possibly to choose the most effective according to the available resolution tools; secondly it is possible to use a generic resolution paradigm, such as a linear programming solver, or specialize an algorithm by including specific heuristics and knowledge to optimize its performance. This thesis is in this second approach. This is often necessary when the problems addressed become complex and / or large and that we need to be designing more efficient algorithms
Pieume, Calice Olivier. "Multiobjective optimization approaches in bilevel optimization." Phd thesis, Université Paris-Est, 2011. http://tel.archives-ouvertes.fr/tel-00665605.
Do, Van Dong. "Usinage à grande vitesse efficace basé sur l'identification opérationnelle du comportement dynamique et l'optimisation du support de pièce." Thesis, Université Clermont Auvergne (2017-2020), 2020. http://www.theses.fr/2020CLFAC036.
High-speed machining plays a very important role in the engineering industry today. However, vibration phenomena during machining process can be detrimental to the quality of machined workpiece, the productivity and the durability of accessories, etc. Mastering the dynamic behavior of the coupled system (machine tool/spindle/tool/workpiece/workpiece holder) is the primordial key to successful high speed machining. The first objective of the thesis consisted in applying existing techniques of operational modal identification and proposing new identification techniques better adapted to take into account the specificities of machining: the presence of very predominant harmonics, the uncontrolled and unmeasured random excitation, and responses only recorded. Three new operational modal identification procedures have been proposed: the transmissibility method (PSDTM-SVD) (i) combined with kurtosis values and histograms, (ii) or hybridized with autocorrelation functions, (iii) and the new SCA-FDD method based on blind source separation. The effectiveness of the proposed methods has been validated by numerical examples and an experimental test. The second objective of the thesis was to propose a new design of the workpiece support using innovative materials, in order to make the dynamic behavior optimal with respect to machining stability. To increase the machining performance, the new composite workpiece holder must have a stiffness at least equal to that of the initial aluminum workpiece holder while having a higher damping ratio. A new hybrid composite laminate reinforced by carbon and flax fibers is then proposed. This combination enables to combine the advantages of two fiber types in a composite. Workpiece holders in carbon-flax hybrid composite laminates with different stacking sequences were fabricated for validation tests. In the case of machining with the composite workpiece holders, the machining stability is greatly increased compared to the initial aluminum workpiece holder. Among the different stacking sequences, the carbon-flax hybrid composite workpiece holder [C6/L8/C6] is the optimal solution in terms of machining performance and environmental impact. This solution increases machining stability by 283 % with a vegetable fiber volume ratio of 14 %
Alaoui, Fdili Othmane. "Optimisation multicritères de la qualité de service dans les réseaux de capteurs multimédia sans fil." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0016/document.
Thanks to the valuable advances in Micro Electro-Mechanical Systems coupled with their convergence to wireless communication systems, the Wireless Sensor Networks (WSN). In the WSN context, all the efforts are made in order to propose energy-efficient solutions. With the recent developments in CMOS technology, low-cost imaging sensors have been developed. As a result, a new derivative of the WSN, which is the Wireless Video Sensor Network (WVSN), has been proposed. The particularities of the video data as well as the inherent constraints of the nodes have introduced new challenges. In this thesis, we propose two cross-layer based solutions for video delivery over the WVSN. The first solution proposes a new energy efficient and adaptive video compression scheme dedicated to the WVSNs, based on the H.264/AVC video compression standard. The video stream is then handled by an enhanced version of MMSPEED protocol, that we propose and note EQBSA-MMSPEED. Performance evaluation shows that the lifetime of the network is extended by 33%, while improving the video quality of the received stream by 12%. In the second solution, we enrich our compression scheme with mathematical models to predict the energy consumption and the video distortion during the encoding and the transmission phases. The video stream is then handled by a novel energy efficient and improved reliability routing protocol, that we note ERMM. Compared to a basic approach, this solution is extending the network lifetime by 15%, while improving the quality of the received video stream by 35%
Liu, Ziming. "Méthodes hybrides d'intelligence artificielle pour les applications de navigation autonome." Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ4004.
Autonomous driving is a challenging task that has a wide range of applications in the real world. The autonomous driving system can be used in different platforms, such as cars, drones, and robots. These autonomous systems will reduce a lot of human labor and improve the efficiency of the current transportation system. Some autonomous systems have been used in real scenarios, such as delivery robots, and service robots. In the real world, autonomous systems need to build environment representations and localize themselves to interact with the environment. There are different sensors can be used for these objectives. Among them, the camera sensor is the best choice between cost and reliability. Currently, visual autonomous driving has achieved significant improvement with deep learning. Deep learning methods have advantages for environment perception. However, they are not robust for visual localization where model-based methods have more reliable results. To utilize the advantages of both data-based and model-based methods, a hybrid visual odometry method is explored in this thesis. Firstly, efficient optimization methods are critical for both model-based and data-based methods which share the same optimization theory. Currently, most deep learning networks are still trained with inefficient first-order optimizers. Therefore, this thesis proposes to extend efficient model-based optimization methods to train deep learning networks. The Gaussian-Newton and the efficient second-order methods are applied for deep learning optimization. Secondly, the model-based visual odometry method is based on the prior depth information, the robust and accurate depth estimation is critical for the performance of visual odometry module. Based on traditional computer vision theory, stereo vision can compute the depth with the correct scale, which is more reliable than monocular solutions. However, the current two-stage 2D-3D stereo networks have the problems of depth annotations and disparity domain gap. Correspondingly, a pose-supervised stereo network and an adaptive stereo network are investigated. However, the performance of two-stage networks is limited by the quality of 2D features that build stereo-matching cost volume. Instead, a new one-stage 3D stereo network is proposed to learn features and stereo-matching implicitly in a single stage. Thirdly, to keep robust, the stereo network and the dense direct visual odometry module are combined to build a stereo hybrid dense direct visual odometry (HDVO). Dense direct visual odometry is more reliable than the feature-based method because it is optimized with global image information. The HDVO is optimized with the photometric minimization loss. However, this loss suffers noises from the occlusion area, homogeneous texture area, and dynamic objects. This thesis explores removing noisy loss values with binary masks. Moreover, to reduce the effects of dynamic objects, semantic segmentation results are used to improve these masks. Finally, to be generalized for a new data domain, a test-time training method for visual odometry is explored. These proposed methods have been evaluated on public autonomous driving benchmarks, and show state-of-the-art performances
Grivet, Sébastien. "Dépliages efficaces de réseaux de Petri." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12915.
Bompard, Manuel. "MODÈLES DE SUBSTITUTION POUR L'OPTIMISATION GLOBALE DE FORME EN AÉRODYNAMIQUE ET MÉTHODE LOCALE SANS PARAMÉTRISATION." Phd thesis, Université Nice Sophia Antipolis, 2011. http://tel.archives-ouvertes.fr/tel-00771799.
Suarez, Rivera Luis Alberto. "Optimisation des techniques et déploiements radio pour les réseaux efficaces en énergie." Télécom Bretagne, 2013. http://www.telecom-bretagne.eu/publications/publication.php?idpublication=14140.
The world of information technology and communications is in a stage of continuous improvement. These new developments are accompanied by a very rapid data traffic growth, particularly for mobile wireless networks. An important effect is the increase of the consumed energy by the network, particularly the radio access section, i. E. The base station systems. This latter issue causes that operational costs associated to energy consumption become more significant for telecommunication operators. In addition to the question of the availability of energy, this problem has an ecological aspect, due to the CO2 emissions associated with the operation of the network but also an issue related to public health given the effects of electromagnetic radiation from wireless transmission. For these reasons, great research efforts in the so-called field of Green Radio are being done in the recent years. The aim of this thesis consisted of finding ways to reduce the energy consumption in wireless and mobile networks respecting the QoS levels assigned to users. After a study of the state of the art analysing the possible approaches, we proposed a set of energy efficient techniques supported on the cell breathing and hybrid cellular networks (macro/femtocells). Our proposed decision making mechanisms include distributed strategies and other features such as the use of a novel multimetric approach. In our work, we also take into account the energy consumption of mobile devices, an issue that to the best of our knowledge was not quite analysed so far. The use of renewable energy sources is also considered into our proposals. Our thesis work includes the study of the consequences of our radio resource management algorithms on the electromagnetic radiation taking into account the acceptable EM exposure thresholds. In the perspectives of future work, we can mention the improvement of our techniques with learning mechanisms and cognitive radio
Zucca, Vincent. "Towards efficient arithmetic for Ring-LWE based homomorphic encryption." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS080.pdf.
Fully homomorphic encryption is a kind of encryption offering the ability to manipulate encrypted data directly through their ciphertexts. In this way it is possible to process sensitive data without having to decrypt them beforehand, ensuring therefore the datas' confidentiality. At the numeric and cloud computing era this kind of encryption has the potential to considerably enhance privacy protection. However, because of its recent discovery by Gentry in 2009, we do not have enough hindsight about it yet. Therefore several uncertainties remain, in particular concerning its security and efficiency in practice, and should be clarified before an eventual widespread use. This thesis deals with this issue and focus on performance enhancement of this kind of encryption in practice. In this perspective we have been interested in the optimization of the arithmetic used by these schemes, either the arithmetic underlying the Ring Learning With Errors problem on which the security of these schemes is based on, or the arithmetic specific to the computations required by the procedures of some of these schemes. We have also considered the optimization of the computations required by some specific applications of homomorphic encryption, and in particular for the classification of private data, and we propose methods and innovative technics in order to perform these computations efficiently. We illustrate the efficiency of our different methods through different software implementations and comparisons to the related art
Marmion, Marie-Eleonore. "Recherche locale et optimisation combinatoire : de l'analyse structurelle d'un problème à la conception d'algorithmes efficaces." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2011. http://tel.archives-ouvertes.fr/tel-00682776.
Kessaci, Marie-Éléonore. "Recherche locale et optimisation combinatoire : de l'analyse structurelle d'un problème à la conception d'algorithmes efficaces." Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10169/document.
Many problems from combinatorial optimization are NP-hard, so that exact methods remain inefficient to solve them efficiently. However, metaheuristics are approximation methods known and used for their efficiency. But they often require a lot of parameters, which are very difficult to set in order to provide good performance. As a consequence, a challenging question is to perform such parameter tuning easier, or adaptive.The fitness landscape of given combinatorial optimization problem, based on a search space, a fitness function and a neighborhood relation, allow to characterize the problem structure and make the understanding of the dynamics of search approches possible.This thesis deals with fitness landscape analysis, together with the link with some neighborhood-based metaheuristic classes. We show the influence of the landscape structure on the dynamics of metaheuristics, for two challenging problems from the field of logistics. We analyze the landscape characteristics which help to design efficient local search metaheuristics and/or to set their parameters.Neutrality is one of the main structural characteristic of a landscape. Such landscapes have numerous plateaus, which often inhibits the progress of local search algorithms. After a deep analysis of these plateaus, we prove that this neutral structure cannot be ignored. Then, we use several information linked with neutrality, and particularly with blocking plateaus, in order to design a first local search approach, which appear to efficient and easy to implement. At last, in order to extend our work on the neutral structure, we chose to exploit the neutrality involved in the whole landscape. We propose a new local search algorithm, based on the ability of solutions of a plateau to produce improvement by means of a guiding strategy.The thesis ends with an experimental analysis of the two local search methods presented for neutral problems in order to exploit new characteristics, and then to strengthen the link between fitness landscape analysis and efficient algorithm design
Leconte, Pierre. "Développement et optimisation de techniques de mesure par spectrométrie gamma." Clermont-Ferrand 2, 2006. https://theses.hal.science/docs/00/70/33/03/PDF/2006CLF21684.PDF.
Hugot, Hadrien. "Approximation et énumération des solutions efficaces dans les problèmes d'optimisation combinatoire multi-objectif." Paris 9, 2007. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=2007PA090028.
This thesis deals with the resolution of multi-objective combinatorial optimization problems. A first step in the resolution of these problems consists in determining the set of efficient solutions. Nevertheless, the number of efficient solutions can be very huge. Approximating the set of efficient solutions for these problems constitutes, then, a major challenge. Existing methods are usually based on approximate methods, such as heuristics or meta-heuristics, that give no guarantee on the quality of the computed solutions. Alternatively, approximation algorithms (with provable guarantee) have been also designed. However, practical implementations of approximation algorithms are cruelly lacking and most of the approximation algorithms proposed in the literature are not efficient in practice. This thesis aims at designing approaches that conciliate on the one hand the qualities of the approximate approaches and on the other hand those of the approximation approaches. We propose, in a general context, where the preference relation used to compare solutions is not necessarily transitive, a Generalized Dynamic Programming (GDP) framework. GDP relies on an extension of the concept of dominance relations. It provides us, in particular, with exact and approximation methods that have been proved to be particularly efficient in practice to solve the 0-1 multi-objective knapsack problem. Finally, a last part of our work deals with the contributions of a multi-criteria modelling for solving, in real context, the data association problem. This led us to study the multi-objective assignment problem and, in particular, the resolution of this problem by the means of our GDP framework
Campos, Ciro Guillermo. "Développement de méthodes d'ordonnancement efficaces et appliquées dans un système de production mécanique." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0035/document.
The continuous evolution of manufacturing environments and the growing of customer needings, leads to a faster and more efficient production process that controls an increasing number of parameters. This thesis is focused on the development of decision making methods in order to improve the production scheduling. The industrial partner (Norelem) produces standardized mechanical elements, so many different resource constraints (humans and tools) are presented in its workshop.We study an open shop scheduling problem where one job can follow multiple production sequences because there is no fixed production sequence and the objective function is to minimize the total flow time. In addition, multi-skilled personnel assignment and tool’s availability constraints are involved.Mathematical models: linear and non-linear formulations have been developed to describe the problem. Knowing the exact method limitations in terms of instance sizes because of the duration, heuristics methods have been proposed and compared. Besides that, the multi-objective optimization was exposed to deal with three objectives as total flow time minimization and workload balancing concerning both, humans and machines.The efficiency of these methods was proved by several theoretical instance tests and the application on the real industrial case
Diolez, Gilles. "Maîtrise de la position géométrique des solides : vers de nouveaux outils plus efficaces." Phd thesis, Paris, ENSAM, 2006. http://pastel.archives-ouvertes.fr/pastel-00002351.
Fernbach, Pierre. "Modèles réduits fiables et efficaces pour la planification et l'optimisation de mouvement des robots à pattes en environnements contraints." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30232.
The automatic synthesis of movements for legged robots is one of the long standing challenge of robotics, and its resolution is a prior to the safe deployment of robots outside of their labs. In this thesis, we tackle it with a divide and conquer approach, where several smaller sub-problems are identified and solved sequentially to generate motions in a computationally efficient manner. This decoupling comes with a feasibility issue : how can we guarantee that the solution of a sub-problem is a valid input for the next sub-problem ? To address this issue, this thesis defines computationally efficient feasibility criteria, focused on the constraints on the Center Of Mass of the robot. Simultaneously, it proposes a new formulation of the problem of computing a feasible trajectory for the Center Of Mass of the robot, given a contact sequence. This formulation is continuous, as opposed to traditional approaches that rely on a discretized formulation, which can result in constraint violations and are less computationally efficient. This general formulation could be straightforwardly used with any existing approach of the state of the art. The framework obtained was experimentally validated both in simulation and on the HRP-2 robot, and presented a higher success rate, as well as computing performances order of magnitudes faster than the state of the art
Bubeck, Sébastien. "JEUX DE BANDITS ET FONDATIONS DU CLUSTERING." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2010. http://tel.archives-ouvertes.fr/tel-00845565.
Benki, Aalae. "Méthodes efficaces de capture de front de pareto en conception mécanique multicritère : applications industrielles." Phd thesis, Université Nice Sophia Antipolis, 2014. http://tel.archives-ouvertes.fr/tel-00959099.
Louat, Christophe. "Etude et mise en œuvre de stratégies de coupes efficaces pour des problèmes entiers mixtes 0-1." Versailles-St Quentin en Yvelines, 2009. http://www.theses.fr/2009VERS0060.
The use of cutting planes is since severals years one of the most used methods to improve the search of an optimal solution reducing the search space in a Branch-and-Bound. The work presented here aims at studying several cutting plane methods and at proposing some strategies to integrate them in a resolution method based on Branch-and-Bound algorithm to solve mixed integer 0-1 problems. We present extensive computational experiments in ordrer to try to find efficient cutting plane generation strategies with generic mixted integer 0-1 problems and with different solvers. For this study, some solvers were used to compare their when the same cutting planes are added. Two commercial solver (Cplex and Xpress) and one free solveur (Glpk) are used to test the different strategies in a sequential Branch-and-Bound. One free solver is used to test these strategies in a parallel Branch-and-Bound. To provide an easy way to use these different solvers, a free library (Glop) that allows the user to use some solver with a same code has been created. We first present the different cutting plane methods that were integrated in the library Glop to produce computational experimentents. We then turn our interest on the different strategies we implement, the one being fixed strategies, the other being strategies that adapt to the problem resolution. We present and analyse the results of computational experiments with sequential Branch-and-Bound and in the last part, those obtained with parallel Branch-and-Bound
Ranwez, Vincent. "Méthodes efficaces pour reconstruire de grandes phylogénies suivant le principe du maximum de vraisemblance." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2002. http://tel.archives-ouvertes.fr/tel-00843175.
Chevalier, Cédric. "Conception et mise en oeuvre d'outils efficaces pour le partitionnement et la distribution parallèles de problème numériques de très grande taille." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2007. http://tel.archives-ouvertes.fr/tel-00199898.
creuses.
Nous utilisons pour résoudre ce problème un schéma multi-niveaux dont nous avons parallélisé les phases de contraction et d'expansion.
Nous avons ainsi introduit pour la phase de contraction un nouvel algorithme de gestion des conflits d'appariements distants, tout en
améliorant les algorithmes déjà existants en leur associant une phase
de sélection des communications les plus utiles.
Concernant la phase d'expansion, nous avons introduit la notion de graphe bande qui permet de diminuer de manière très conséquente la taille du problème à traiter par les algorithmes de raffinement. Nous avons généralisé l'utilisation de ce graphe bande aux implantations séquentielles et parallèles de notre outil de partitionnement Scotch.
Grâce à la présence du graphe bande, nous avons proposé une utilisation nouvelle des algorithmes génétiques dans le cadre de
l'expansion en les utilisant comme heuristiques parallèles de raffinement de la partition.
Cherid, Samia. "Conception et etude de nouveaux separateurs lamellaires hydrocarbures-eau de type "spiraloil"." Toulouse, INSA, 1986. http://www.theses.fr/1986ISAT0010.
Handoufe, Abderrahim. "Reponses a l'eau et a l'azote d'un ble tendre (triticum aestivum) sous un climat semi-aride." Toulouse 3, 1988. http://www.theses.fr/1988TOU30237.
Martin, Katerine. "Estimation efficace de dérivées dans un réseau de télécommunications." Thèse, 2004. http://hdl.handle.net/1866/16672.
Vargas-Solar, Genoveva. "Gestion de données efficace, continue et fiable par coordination de services." Habilitation à diriger des recherches, 2014. http://tel.archives-ouvertes.fr/tel-01006214.
Gingras, Véronique. "Optimisation du contrôle glycémique des patients atteints de diabète de type 1 : traitement efficace des hypoglycémies, calcul des glucides et pancréas artificiel." Thèse, 2017. http://hdl.handle.net/1866/20249.
Ouzineb, Mohamed. "Heuristiques efficaces pour l'optimisation de la performance des systèmes séries-parallèles." Thèse, 2009. http://hdl.handle.net/1866/6457.
Chevalier, Cédric. "Conception et mise en oeuvre d'outils efficaces pour le partitionnement et la distribution parallèles de problèmes numériques de très grande taille." Phd thesis, 2007. http://tel.archives-ouvertes.fr/tel-00410402.
Nous utilisons pour résoudre ce problème un schéma multi-niveaux dont nous avons parallélisé les phases de contraction et d'expansion.
Nous avons ainsi introduit pour la phase de contraction un nouvel algorithme de gestion des conflits d'appariements distants, tout en améliorant les algorithmes déjà existants en leur associant une phase de sélection des communications les plus utiles.
Concernant la phase de d'expansion, nous avons introduit la notion de graphe bande qui permet de diminuer de manière très conséquente la taille du problème à traiter par les algorithmes de raffinement. Nous avons généralisé l'utilisation de ce graphe bande aux implantations séquentielles et parallèles de notre outil de partitionnement Scotch.
Grâce à la présence du graphe bande, nous avons proposé une utilisation nouvelle des algorithmes génétiques dans le cadre de l'expansion en les utilisant comme heuristiques parallèles de raffinement de la partition.