Tesi sul tema "Décomposition du résidu"
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Coppens, Filip. "Influence de la localisation et de la qualité des résidus de culture sur les dynamiques de l'eau, du carbone et de l'azote dans le sol". Phd thesis, Institut national agronomique paris-grignon - INA P-G, 2005. http://tel.archives-ouvertes.fr/tel-00121922.
L'objectif principal de cette thèse est l'identification des processus physiques et biologiques qui sont influencés par la localisation des résidus dans le sol, en interaction avec la qualité de ces résidus. La localisation initiale des résidus modifie des propriétés physiques du sol : les dynamiques d'eau, le transport des solutés ou la température du sol. La qualité biochimique des résidus influence les processus (micro-)biologiques : les biotransformations du carbone et de l'azote, l'activité et la composition des populations microbiennes dans le sol. Ces changements physiques et biologiques interagissent, peuvent modifier la structure du sol (par l'agrégation) et, en retour, influencer la décomposition de la matière organique.
La première partie de ce travail traite de l'influence de la qualité des résidus végétaux et du type de sol sur la minéralisation du C et N en contact 'optimal' avec le sol (incorporation homogène des résidus finement coupés). Il est montré que sous conditions contrôlées et d'azote non limitant, la qualité des résidus est le facteur principal déterminant la vitesse de décomposition. Le type de sol a un effet négligeable sur les dynamiques de décomposition à court terme. Par contre, la minéralisation du carbone à plus long terme dépend du type de sol, ce qui est probablement lié aux différences dans la capacité du sol à stabiliser du carbone soluble ou d'origine microbienne.
La deuxième partie traite de l'effet de la localisation des résidus sur la minéralisation du C et N pour des résidus de colza dans un sol limoneux. Des colonnes de sol sont construites avec des résidus soit incorporés soit laissés à la surface du sol. Les colonnes sont placées périodiquement sous un simulateur de pluie pour simuler des conditions hydriques relativement similaires au champ. L'évaporation du sol est fortement réduite avec le mulch, ce qui conduit à une humidité du sol plus grande que lorsque les résidus sont incorporés. Simultanément, on observe un dessèchement rapide du mulch de résidus. Le C et N issu des résidus est distribué différemment dans le sol selon que ceux-ci sont à la surface ou incorporés. Les différences dans la disponibilité d'eau et des nutriments conduisent à une vitesse de décomposition plus lente pour des résidus à la surface que pour des résidus incorporés dans le sol. Cependant, la minéralisation nette de l'azote est plus grande dans le sol sous mulch qu'avec incorporation des résidus en raison de l'humidité plus grande qui favorise la minéralisation et d'une moindre organisation d'azote.
L'influence de la localisation des résidus sur le devenir du C et N dans le sol et dans les agrégats est examinée afin d'évaluer les mécanismes qui contrôlent le stockage du carbone dans le sol. A court terme, une grande partie de la matière organique particulaire (MOP) est retenue à la surface du sol avec le traitement mulch alors que toute la MOP a disparu quand les résidus sont incorporés. La présence des résidus augmente la taille moyenne des agrégats comparé au sol témoin et des agrégats plus larges sont trouvés dans la couche de sol 0-5 cm sous le mulch que dans la couche ou les résidus sont incorporés. La quantité totale du C des résidus récupérée dans les agrégats est similaire avec les résidus laissés à la surface et les résidus incorporés, mais elle est distribuée différemment dans le profil du sol. Malgré les différences dans la façon dont le C 'nouveau' entre dans le sol, la distribution relative du C des résidus dans les micro et macro agrégats est la même pour les deux localisations, probablement parce que dans les deux cas le C des résidus entre dans les agrégats sous forme soluble.
Finalement, l'interaction entre la localisation des résidus et leur qualité est étudiée. Un mulch réduit fortement l'évaporation du sol et l'importance de cette réduction dépend de la qualité physique du mulch. Des changements dans l'humidité du mulch, identifié comme facteur principal qui détermine la décomposition du mulch, dépend aussi de la qualité (physique) des résidus. Avec l'incorporation des résidus, la vitesse de minéralisation de C est principalement influencée par la qualité biochimique des résidus. L'interaction la plus forte entre localisation et qualité des résidus est observée sur les dynamiques de l'azote : la minéralisation nette de l'azote est déterminée par l'interaction entre l'humidité du sol (effet localisation) et la disponibilité de l'azote (effet qualité). Ces résultats permettent de développer et de calibrer un module du modèle PASTIS (Garnier et al., 2003), conçu pour simuler la décomposition d'un mulch. La modélisation avec PASTISmulch a permis d'avoir accès au flux brut d'azote, d'estimer le transport des nitrates et le lessivage potentiel dans le profil du sol, et de quantifier l'impact de la localisation et qualité des résidus sur la minéralisation du C et N dans le sol.
Guibert, David. "Analyse de méthodes de résolution parallèles d'EDO/EDA raides". Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00430013.
Ibrahima, Adamou. "Approches expérimentale et spectroscopique de la décomposition de litières méditerranéennes". Montpellier 2, 1995. http://www.theses.fr/1995MON20216.
Boittiaux-Zidani, Jacqueline. "Décompositions d'une relation". Habilitation à diriger des recherches, Grenoble 1, 1986. http://tel.archives-ouvertes.fr/tel-00320987.
Vignac, Benoît. "Reformulation et décomposition pour un problème d'allocation de ressources dans un réseau optique". Thesis, Bordeaux 1, 2010. http://www.theses.fr/2009BOR13996/document.
Optical networks are the core element of modern communication systems and in particu- lar Internet. With wavelength multiplexing and grooming capability, terabits per second bandwidth can be reached. However, opto-electronic equipment used to operate these networks are very expensive as their bit rate must be very large. The grooming, routing and wavelength assignment (GRWA) problem, which consists in minimizing the net- work cost, evaluated by the number of required optical ports, while guaranteeing that each request is granted, is of great interest. The GRWA problem can be modeled as a multi-layer capacitated network design problem with non-bifurcated multi-?ows. This type of problem is known to be hard to solve as their linear relaxation is weak. The objective of this work was to develop solution methods based on multiple oper- ations research techniques : Tabu search based meta-heuristic, Dantzig-Wolfe decompo- sition, Benders decomposition, 0 1 reformulation, cutting-planes, rounding heuristic. The resulting solution tools, some of them hybrid, give a perspective on the effective solution approaches for this type of problem. From the experiments, it turns out that the methods based on Benders’ decomposition, which lead to hierarchical optimization procedures, are the most ef?cient as they allow to separate the optical routing from the physical routing with the wavelength assignment decisions taken in the lower stage sub- problem. In addition to the approach comparison, we use the most effective method to evaluate the impact of the delay constraints on the solution quality
Guibert, David. "Analyse de méthodes de résolution parallèles d’EDO/EDA raides". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10138/document.
This PhD Thesis deals with the development of parallel numerical methods for solving Ordinary and Algebraic Differential Equations. ODE and DAE are commonly arising when modeling complex dynamical phenomena. We first show that the parallelization across the method is limited by the number of stages of the RK method or DIMSIM. We introduce the Schur complement into the linearised linear system of time integrators. An automatic framework is given to build a mask defining the relationships between the variables. Then the Schur complement is coupled with Jacobian Free Newton-Krylov methods. As time decomposition, global time steps resolutions can be solved by parallel nonlinear solvers (such as fixed point, Newton and Steffensen acceleration). Two steps time decomposition (Parareal, Pita,...) are developed with a new definition of their grids to solved stiff problems. Global error estimates, especially the Richardson extrapolation, are used to compute a good approximation for the second grid. Finally we propose a parallel deferred correction
Gilles, Jérôme. "Décomposition et détection de structures géométriques en imagerie". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2006. http://tel.archives-ouvertes.fr/tel-00089549.
Après une étude théorique de ces approches, nous proposons une extension au cas des images bruitées nous permettant d'obtenir alors une décomposition en trois composantes: structures + textures + bruit.
Par ailleurs, nous proposons une méthode spécifique en vue d'évaluer les résultats obtenus à partir des différents alggorithmes.
Enfin, nous présentons quelques applications des ces méthodes de décomposition d'image, notamment un algorithme de détection de réseaux routiers en imagerie aérienne ou satellitaire. Cet algorithme combine décomposition d'image, détection d'alignements par la théorie de la Gestalt et modèle déformable.
Bosco, Gilles. "Synthèse et décomposition technologique sur réseaux programmables et ASICs". Phd thesis, Grenoble INPG, 1996. http://tel.archives-ouvertes.fr/tel-00346210.
Mrad, Fida. "Décomposition de résidus de culture et de matériaux biosourcés : impact sur les communautés microbiennes des sols agricoles et les fonctions associées". Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR109/document.
Waste management is a major problem worldwide. In agriculture, the return of crop residues to the soil is a common practice and represents an interesting opportunity to maintain soil fertility and / or to store carbon. The decomposition of plant materials in soils is influenced by several factors (such as microbial composition, plant material’s nature and quality), and soil microorganisms are its main actors. Moreover, other ways of valorization of non-harvested plant materials are possible, such as their transformation for non-food applications. In the building industry, the interest in using biobased materials (for thermal insulation) is growing and encouraged by the public authorities in construction or renovation projects. However, to our knowledge, the issue of management of these materials end-of-life is not yet addressed, after deconstructing the buildings. In order to better understand different crop residues (wheat straw, rapeseed straw and sunflower stems) decomposition in agricultural soils, we have combined different biochemical / physicochemical characterizations such as biochemical fractionation, thermogravimetric analysis and infrared spectroscopy, with microbial dynamics monitoring (abundance, diversity, function), supplemented by carbon and nitrogen mineralization measures during 3 months incubation in microcosms. Crop residues mineralization is mainly governed by initially different microbiodiversities (derived from permanent grassland or conventional cropping system), and to a lesser extent by their biochemical quality. However, microbial dynamics are influenced by both, types of soils and nature of inputs. As for the sunflower stem coproducts (pith and bark), C mineralization is mainly dictated by their initial quality. Concerning the manufacturing process of a sunflower pith biobased material, it seems to favor its mineralization in soil. The return of this type of material to soil could thus constitute an interesting means of managing its end-of-life
Niknahad, Ghar Makher Hamid. "Minéralisation du soufre associée à la décomposition des matières organiques dans les sols et relations avec les dynamiques du carbone et de l'azote". Paris, AgroParisTech, 2008. http://www.theses.fr/2008AGPT0051.
Wang, Yipeng. "Estimation d’erreur a posteriori pour des calculs de structure électronique par des méthodes ab initio et son application pour diminuer le coût de calcul". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS656.
The thesis is concerned with the error analysis of electronic structure calculation. The long term goal is to, in one hand, derive computable a posteriori error estimator for ab initio methods and, in the other hand, propose near-optimal computational cost strategy for the numerical calculation of those methods based on the a posteriori error estimation and the separation of the discretization and iteration error sources.In the first part of the thesis, we introduce a new well-posedness analysis for the single reference coupled cluster method based on the invertibility of the CC derivative. Under the minimal assumption that the sought-after eigenfunction is intermediately normalisable and the associated eigenvalue is isolated and non-degenerate, we prove that the continuous (infinite-dimensional) CC equations are always locally well-posed. Under the same minimal assumptions and provided that the discretization is fine enough, we prove that the discrete Full-CC equations are locally well-posed, and we derive residual-based error estimates with guaranteed positive constants.The second part of the thesis focus on the application of a posteriori error estimation to construct near-optimal path when approximating the solution of PDEs. We firstly apply a probabilistic method to explore an optimal path that minimizes the cost for the numerical resolution of linear and nonlinear elliptic source problems. Based on the analysis of those optimal paths, we propose two near-optimal strategies to achieve a given accuracy based on the error sources decomposition of the error estimator. Finally, we validate the feasibility of those near-optimal strategies by applying them to the numerical approximation of a nonlinear eigenvalue problem, i.e., the Gross-Pitaevskii equation
Bellalouna, Kamel. "Résolution d'E. D. P. Par méthode spectrale sur un réseau de cylindres". Paris 6, 2007. http://www.theses.fr/2007PA066395.
Sall, Saïdou Nourou. "Importance des relations "Résidus végétaux-Communautés microbienne" sur les processus de décomposition dans un sol ferrugineux tropical (Sénégal) : effet de la disponibilité de l'azote". Paris 12, 2004. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990002156110204611&vid=upec.
The relationship between organic residues and the microbial communities in a tropical sandy soil and its effects on CO2 and mineral N respiration were studied, taking into account the effect of the composition of the residues as well as the genetic and catabolic diversity of the microbial communities involved in this process. The experiments were carried out in controlled laboratory conditions and showed that the biochemical composition of the residues determined the activity (C and N respiration, enzyme activities) and the microbial biomass. However, the formation of complexes between the nitrogen released during decomposition and other components of the organic residues (phenols) slowed the process. The fungal community was the most sensitive to the addition of litter at the same time as mineral nitrogen. The addition of litter stimulated the decomposition of the organic matter in the soil (priming effect) to a degree that varied depending on the composition of the residues. The effect of the catabolic diversity of the microbial community was particularly evident during the initial hours of decomposition
Niknahad, ghar makher Hamid. "Minéralisation du soufre associée à la décomposition des matières organiques dans les sols et relations avec les dynamiques du carbone et de l'azote". Phd thesis, AgroParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00004764.
Berdjag, Denis. "Méthodes algébriques pour la décomposition de modèles comportementaux : Application à la détection et à la localisation de défaillances". Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2007. http://tel.archives-ouvertes.fr/tel-00385550.
Iqbal, Akhtar. "Effets de la nature et décomposition des mulchs de résidus végétaux sur les services assurés par les sols en agriculture de conservation : Étude expérimentale et modélisation". Thesis, Reims, 2013. http://www.theses.fr/2013REIMS001.
In conservation agriculture (CA), crop residues mulches are associated to reduction or suppression of soil tillage and are an intrinsic component of CA. The objective of this work was to understand the effects of nature and decomposition of crop residue mulches on the provisioning and regulating services of agrosystems provided by soils under temperate (France) and tropical (Madagascar and Brazil) conditions. Experimental studies were realized to get decomposition parameters for a large range of residue quality representative of the agrosystems studied and to test and improve a MULCH model. Then we used PASTIS_MULCH model which simulates the C and N biotransformations and solutes transport in soils during mulch decomposition.For a range of plant-stem residues tested, the maximal water retention varied greatly and was only explained by the physical features of the residue. With a series of decomposition incubations, we proposed a single set of biological parameters for CANTIS decomposition module, simulating a large range of crop residue quality. Experimental study in soil columns showed that maize+dolichos mulch decomposed faster than wheat+alfalfa mulch. Frequent and light rain enhanced mulch decomposition compared to infrequent and heavy rain and this was due to the mulch remaining wetter with frequent rain.The simulations of scenarios with PASTIS showed that rain and evaporation conditions ranked crop residues decomposition when placed as mulches while the residue chemical characteristics ranked crop residues decomposition when incorporated. None of the situations studied would be defined as suitable in all pedo-climatic and agricultural conditions
Bourgin, Marc. "Étude de la décomposition de produits phytosanitaires par l'ozone : Application au traitement des semences déclassées". Phd thesis, Toulouse, INPT, 2011. http://oatao.univ-toulouse.fr/16230/1/bourgin.pdf.
Rezig, Wafa. "Problèmes de multiflots : état de l'art et approche par décomposition décentralisée du biflot entier de coût minimum". Phd thesis, Université Joseph Fourier (Grenoble), 1995. http://tel.archives-ouvertes.fr/tel-00346082.
Hassine, Khaled. "Contribution à l'élaboration d'une approche de décomposition des traitements itératifs sur des architectures MIMD : application aux traitements de séquences d'images sur réseau de transputers". Valenciennes, 1994. https://ged.uphf.fr/nuxeo/site/esupversions/6059845e-087a-474f-94a6-09cb96fbf246.
Rafrafi, Meriem. "Une approche harmonisée pour l'évaluation de la sécurité des systèmes ferroviaires : de la décomposition fonctionnelle au modèle comportemental". Phd thesis, Ecole Centrale de Lille, 2010. http://tel.archives-ouvertes.fr/tel-00586085.
Cherkashyn, Valeriy. "Représentation adaptative d'images de télédétection à très haute résolution spatiale une nouvelle approche hybride (la décomposition pyramidale avec des réseaux de neurones)". Thèse, Université de Sherbrooke, 2011. http://hdl.handle.net/11143/5831.
Lemattre, Alexis. "Développement de résines polyester insaturées ignifugées : caractérisation des performances feu/fumées et détermination des mécanismes de décomposition". Thesis, Mulhouse, 2018. http://www.theses.fr/2018MULH2179.
For many years, unsaturated polyester (UP) resins and composites markets are growing. Indeed, the wide range of UP resins gives a large physico-chemical and mechanical properties to composites. These properties and the good performance / price ratio explain the market growth of these resins in industrial applications like composites or gel coats for transportation and construction. However, UP resin exhibit low flammability and the enhancement of their fire behaviour is needed to meet the legislation and to protect goods and people. Since 2018, the European legislation for fire protection used in railway applications (EN45545-2) has strengthened and been harmonized. Smoke opacity and toxicity are the main issue of halogenated unsaturated polyester resins currently used on this market. The aims of this study were thus to develop and formulate new halogen-free and low viscosity UP resins presenting good flame retardant properties. A synergist mixture of reactive and additive flame retardants (FR) was found to be the solution to substitute brominated UP resins and meet the industrial specifications. Finally, the use of such a resin enables developing flame retardant composites without affecting their physico-chemical and mechanical properties
Monoury, Eve. "Fonctionnement écologique des zones de dépôt dans les ruisseaux : contribution des invertébrés benthiques aux processus de décomposition des litières et de bioturbation". Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00978432.
Trinsoutrot-Gattin, Isabelle. "Influence de la qualité biochimique et de la teneur en azote de résidus de colza (Brassica napus L) sur les biotransformations du carbone et de l'azote au cours de leur décomposition dans le sol". Lyon 1, 1999. http://www.theses.fr/1999LYO10070.
Pascault, Noémie. "Réponse des communautés microbiennes du sol à l'apport de résidus de culture : influence des pratiques agricoles et lien avec le fonctionnement biologique du sol". Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00582567.
Sauvadet, Marie. "Impacts de la qualité et quantité des résidus de culture sur la structure et le fonctionnement des communautés du sol. Application aux systèmes de grandes cultures du Nord-Est de la France". Thesis, Reims, 2016. http://www.theses.fr/2016REIMS041.
Crop residues decomposition is an essential process in cultivated lands since it constitutes the main source of organic matter in these systems. Although the underlying mechanisms of residues degradation of varying qualities and quantities are well-known, their consequences on soil biota and the related functions are less understood. To better understand this process, we chose to follow at key steps of decomposition the evolution of major components of soil diversity (microorganisms, nematodes, micro-arthropods and macrofauna), the evolution of litter quality, the main carbon (C) and nitrogen (N) fluxes and enzyme activities associated, for different quantities and qualities of litter added. The experiments were set up at different spatial and temporal scales (field, mesocosm and microcosm experiments) in function of our objectives.Litter quantity and quality have distinct effects on soil biota. Litter quantity influences the detritivores, and litter quality influences more generally the main functional groups. Labile litter impacts more the bacterial energy channel and the macrodetritivores at the first stages of decomposition, and recalcitrant litter impacts more the fungal energy channel and the mesodetritivores at the latter stage of decomposition. These evolutions are mirrored by the enzymatic dynamics. More specifically, fauna top-down regulations (L.terrestris and nematodes manipulations) exhibit high effects on soil enzymes. Similarly, soil micro-food web initial composition drives enzymatic dynamics. Contrastingly, litter C mineralization depends mainly on its initial quality. This PhD shows the importance of litter management on the biological functions of cultivated soils. Varying litter quality and quantity appear as a mean to influence soil health and some ecosystem services on the long term
Delmas, Olivier. "Communications par commutation de circuits dans les réseaux d'interconnexion". Phd thesis, Université de Nice Sophia-Antipolis, 1997. http://tel.archives-ouvertes.fr/tel-00407405.
Dans le chapitre 1 nous présentons brièvement une rapide classification des machines parallèles. Puis nous décrivons en détails les principaux mécanismes de routage des messages existant à l'heure actuelle dans de telles machines. Nous détaillons en particulier, les nouveaux mécanismes de routage du type "wormhole". Ce chapitre contient également un bref rappel des principales notions de théorie des graphes utilisées pour la modélisation des machines parallèles à mémoire distribuée.
Les chapitres 2, 3 et 4 dressent une synthèse des travaux qui nous paraissent les plus significatifs sur quelques principaux problèmes de communications globales (diffusion, échange total et multidistribution) par commutation de circuits, tout au moins lorsque l'on cherche essentiellement à minimiser le nombre d'étapes des protocoles.
Dans le chapitre 5 nous résumons en premier lieu nos travaux sur la décomposition hamiltonienne du réseau Butterfly généralisé, puis en second lieu nous donnons notre approche au problème des larges graphes à degré et diamètre fixés.
Romier, Maxime. "Simulation électromagnétique des antennes actives en régime non-linéaire". Phd thesis, Toulouse, INPT, 2008. http://oatao.univ-toulouse.fr/7824/1/romier.pdf.
Royer, Alexandre. "Evaluation de performances de réseaux de communication à l'aide de chaînes de Markov hybrides". Phd thesis, Grenoble INPG, 2006. http://tel.archives-ouvertes.fr/tel-00168342.
Akkari, Samy. "Contrôle d'un système multi-terminal HVDC (MTDC) et étude des interactions entre les réseaux AC et le réseau MTDC". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC069/document.
HVDC transmission systems are largely used worldwide, mostly in the form of back-to-back and point-to-point HVDC, using either thyristor-based LCC or IGBT-based VSC. With the recent deployment of the INELFE HVDC link between France and Spain, and the commissioning in China of a three-terminal HVDC transmission system using Modular Multilevel Converters (MMCs), a modular design of voltage source converters, the focus of the scientific community has shifted onto the analysis and control of MMC-based HVDC transmission systems. In this thesis, the average value models of both a standard 2-level VSC and an MMC are proposed and the most interesting difference between the two converter technologies -the control of the stored energy in the MMC- is emphasised and explained. These models are then linearised, expressed in state-space form and validated by comparing their behaviour to more detailed models under EMT programs. Afterwards, these state-space representations are used in the modelling of HVDC transmission systems, either point-to-point or Multi-Terminal HVDC (MTDC). A modal analysis is performed on an HVDC link, for both 2-level VSCs and MMCs. The modes of these two systems are specifed and compared and the independent control of the DC voltage and the DC current in the case of an MMC is illustrated. This analysis is extended to the scope of a 5-terminal HVDC system in order to perform a stability analysis, understand the origin of the system dynamics and identify the dominant DC voltage mode that dictates the DC voltage response time. Using the Singular Value Decomposition method on the MTDC system, the proper design of the voltage-droop gains of the controllers is then achieved so that the system operation is ensured within physical constraints, such as the maximum DC voltage deviation and the maximum admissible current in the power electronics. Finally, a supplementary droop "the frequency-droop control" is proposed so that MTDC systems also participate to the onshore grids frequency regulation. However, this controller interacts with the voltage-droop controller. This interaction is mathematically quantified and a corrected frequency-droop gain is proposed. This control is then illustrated with an application to the physical converters of the Twenties project mock-up
Ogier, Maxime. "Contributions à la chaine logistique numérique : conception de circuits courts et planification décentralisée". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00981923.
Babba, Belgacem. "Synthèse optimisée sur les réseaux programmables de la famille Xilinx". Phd thesis, Grenoble INPG, 1995. http://tel.archives-ouvertes.fr/tel-00346062.
Koroko, Abdoulaye. "Natural gradient-based optimization methods for deep neural networks". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASG068.
The stochastic gradient method is currently the prevailing technology for training neural networks. Compared to a classical descent, the calculation of the true gradient as an average over the data is replaced by a random element of the sum. When dealing with massive data, this bold approximation enables one to decrease the number of elementary gradient evaluations and to alleviate the cost of each iteration. The price to be paid is the appearance of oscillations and the slowness of convergence, which is often excessive in terms of number of iterations. The aim of this thesis is to design an approach that is both: (i) more robust, using the fundamental methods that have been successfully proven in classical optimization, i.e., outside the learning framework; and (ii) faster in terms of convergence speed. We are especially interested in second-order methods, known for their stability and speed of convergence. To circumvent the bottleneck of these methods, which lies in the prohibitive cost of an iteration involving a linear system with a full matrix, we attempt to improve an approximation recently introduced as Kronecker-Factorized Approximation of Curvature (KFAC) for the Fisher matrix, which replaces the Hessian matrix in this context. More specifically, our work focuses on: (i) building new Kronecker factorizations based on a more rigorous mathematical justification than in KFAC; (ii) taking into account the information from the off-diagonal blocks of the Fisher matrix, which represent the interaction between the different layers; (iii) generalizing KFAC to a network architecture other than those for which it had been initially developed
Martino, Marcelo Gonçalves de. "On the unramified spherical automorphic spectrum". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4017/document.
This thesis contains two results on harmonic analysis of reductive groups. First, let G be connected and defined over a number field F, A be the ring of adèles and K be a maximal compact subgroup of G(A). We studied the decomposition of the space of square-integrable functions on the quotient G(F)\G(A)/K, as a module for a global Hecke algebra. Similar results than the ones obtained here have been established by various authors for many special cases of reductive groups. The main feature of the present approach is the fact that it is uniform. Such approach was greatly inspired by results of G. Heckman and E. Opdam in treating spectral problems for graded affine Hecke algebras. In the proof, we need a result by M. Reeder on the weight spaces of the (anti)spherical discrete series representations of affine Hecke algebras, as well as we are faced with the problem of computing certain rational constants factors involved in the global spectral measure in terms of local Plancherel measures which are known only in the affine Hecke algebra context. As for the second result, we show that a Coxeter complex and a Euclidean building can be endowed with piecewise linear Morse functions that allows one to write down explicit contractions of the underlying cell complexes. Such approach via PL Morse theory to study buildings was heavily inspired by ideas from G. Savin and M. Bestvina in the specific case of the building of SL(n). We conjecture that these contractions have nice bounds on their coefficients and thus can be used to compute Ext groups between tempered representations in an analogous way as was done by M. Solleveld and E. Opdam
Hekmati, Abbas. "Analyse des évènements aérodynamiques à l'origine des émissions sonores à partir de simulations numériques". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00734572.
Bécavin, Christophe. "Reduction de dimensionalité et analyse des réseaux de voies de signalisation pour les données de transcriptome: Appliquation à la caractérisation des cellules T". Phd thesis, Ecole Normale Supérieure de Paris - ENS Paris, 2010. http://tel.archives-ouvertes.fr/tel-00563238.
Castano, Giraldo Fabian Andres. "Decomposition-based approaches for the design of energy efficient wireless sensor networks". Thesis, Lorient, 2014. http://www.theses.fr/2014LORIS338/document.
Energy is a major concern in wireless sensor networks (WSN). These devices are typically battery operated and provided with a limited amount of energy. As a consequence, the time during which sensors can monitor the interesting phenomena and communicate through wireless signals might be limited because of (sometimes) irreplaceable batteries. Additionally, it is very common for WSN to be usedin remote or hostile environments which possibly makes necessary a random placement strategy (by using an airplane, a drone or a helicopter). Hence, the sensors location is not known a priori and approaches to efficiently use the energy are needed to answer to network topologies only known after sensors deployment. This thesis explores the use of column generation to efficiently use the energy in WSN. It is shown that column generation can be used as a general framework to tackle different problems in WSN design. Several versions of the problem and models for the operation of the WNS are adapted to be solved through column generation. These approaches take advantage of the natural way that column generation offers to consider different features of the WSN operation. Additionally, some computational improvements are proposed to keep the column generation method operating as an efficient exact approach. Hybrid strategies combining column generation with (meta)heuristic and exact approaches are considered and evaluated. The computational experiments demonstrate the efficiency of the proposed approaches and provide practitioners on WSN research with strategies to compute upper bounds to evaluate heuristic centralized and decentralized approaches. Finally, some future directions of research are provided based on the performance and adaptability of column generation to consider more sophisticated models and characteristics newly introduced in sensor devices
Awasthi, Anjali. "Développement d'un système de routage hiérarchique pour les réseaux urbains". Phd thesis, Université de Metz, 2004. http://tel.archives-ouvertes.fr/tel-00007751.
La deuxième partie de la thèse est consacrée au problème de décomposition d'un réseau urbain en sous réseaux de taille raisonnable et aussi indépendants les uns des autres que possible, c'est-à-dire ayant un nombre de connexions
aussi faible que possible.
Dans la troisième partie de la thèse nous présentons un programme de simulation pour générer les données qui, à leur tour, vont servir à constituer une mémoire. Cette mémoire a pour objectif de proposer le chemin le plus rapide à l'intérieur d'un sous-réseau dès que l'on connaît l'état du sous-réseau ainsi que l'origine et la destination du véhicule.
Enfin, la dernière partie de la thèse est la plus novatrice. Elle fait intervenir les techniques de l'analyse des données pour constituer la mémoire et permettre ainsi de choisir le chemin le plus rapide en temps réel.
Strogova, Polina. "Techniques de réécriture pour le traitement de problème de routage dans les graphes de Cayley". Nancy 1, 1996. http://www.theses.fr/1996NAN10352.
Oorts, Katrien. "Effet de travail du sol sur les stocks et flux de C et N dans un sol limoneux de grandes cultures du bassin Parisien". Phd thesis, Institut national agronomique paris-grignon - INA P-G, 2006. http://tel.archives-ouvertes.fr/tel-00011985.
Bai, Lijie. "Ordonnancement des trains dans une gare complexe et à forte densité de circulation". Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0017/document.
This thesis focuses on the trains platforming problem within busy and complex railway stations and aims to develop a computerized dispatching support tool for railway station dispatchers to generate a full-day conflict-free timetable. The management of rail traffic in stations requires careful scheduling to fit to the existing infrastructure, while avoiding conflicts between large numbers of trains and satisfying safety or business policy and objectives. Based on operations research techniques and professional railway expertise, we design a generalized mathematical model to formalize the trains platforming problem including topology of railway station, trains' activities, dispatching constraints and objectives. As a large-scale problem, full-day platforming problem is decomposed into tractable sub-problems in time order by cumulative sliding window algorithm. Each sub-problem is solved by branch-and-bound algorithm implemented in CPLEX. To accelerate calculation process of sub-problems, tri-level optimization model is designed to provide a local optimal solution in a rather short time. This local optimum is provided to branch-and bound algorithm as an initial solution.This system is able to verify the feasibility of tentative timetable given to railway station. Trains with unsolvable conflicts will return to their original activity managers with suggestions for the modification of arrival and departure times. Time deviations of commercial trains' activities are minimized to reduce the delay propagation within the whole railway networks
Le, Ny Mathieu. "Diagnostic non invasif de piles à combustible par mesure du champ magnétique proche". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00844407.
Nguyen, Phuong. "Ethnic gap, household businesses and social networks in Vietnam The role of Social Networks on Household Business Performance in Vietnam: A qualitative assessment". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLED080.
Over the past two decades, the two vulnerable groups of ethnic minorities and household businesses have participated in the economic growth but could not benefit from the growth process as much as the other groups in Vietnam. The inadequate inclusiveness of these two groups in the economic growth calls for an investigation of the ethnic gap and household businesses' performance with a lens of social networks. This study aims to examine the role of social networks, using a Q-squared method to analyze an original dataset, which combined both the quantitative and qualitative datasets on social networks of household businesses. In doing so, the study employs an innovative instrument of being the first son in the family. Chapter 1 measures and analyses the main drivers of the ethnic gap over the last ten years. Chapter 2 identifies the causal effects of social networks on household businesses' performance. Chapter 3 presents a qualitative analysis of the impact of social networks on business performance by the content and the strength of social relationships, and the business phase
Aubry, Alexandre. "Approche matricielle de l'opérateur de propagation des ondes ultrasonores en milieu diffusant aléatoire". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://pastel.archives-ouvertes.fr/pastel-00004213.
Berrebi, Johanna. "Contribution à l'intégration d'une liaison avionique sans fil. L'ingénierie système appliquée à une problématique industrielle". Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00800141.
Ould, Ebede Mohamed. "Design optimal de réseau multipoint survivable". Thèse, 2006. http://hdl.handle.net/1866/16712.
Dubois, Valérie. "Décomposition des produits de fonctions d'orbites symétriques et antisymétriques des groupes de Weyl". Thèse, 2006. http://hdl.handle.net/1866/17297.
Benyamina, Djohara. "Conception des réseaux maillés sans fil à multiples-radios multiples-canaux". Thèse, 2010. http://hdl.handle.net/1866/4317.
Generally, network design problems consist of selecting links and vertices of a graph G so that a cost function is optimized and all constraints involving links and the vertices in G are met. A change in the criterion of optimization and/or the set of constraints leads to a new representation of a different problem. In this thesis, we consider the problem of designing infrastructure Wireless Mesh Networks (WMNs) where we show that the design of such networks becomes an optimization problem with multiple objectives instead of a standard optimization problem (a cost function is optimized) to take into account many aspects, often contradictory, but nevertheless essential in the reality. This thesis, composed of three parts, introduces new models and algorithms for designing WMNs from scratch. The first part is devoted to the simultaneous optimization of two equally important objectives: cost and network performance in terms of throughput. Three bi-objective models which differ mainly by the approach used to maximize network performance are proposed, solved and compared. The second part deals with the problem of gateways placement, given its impact on network performance and scalability. The concept of hop constraints is introduced into the network design to reduce the transmission delay. A novel algorithm based on a clustering approach is also proposed to find the strategic positions of gateways that support network scalability and increase its performance without significantly increasing the cost of installation. The final section addresses the problem of reliability in the presence of single failures. Allowing the installation of redundant components in the design phase can ensure reliable communications, but at the expense of cost and network performance. A new algorithm is developed based on the theoretical approach of "ear decomposition" to install the minimum number of additional routers to tolerate single failures. In order to solve the proposed models for real-size networks, an evolutionary algorithm (meta-heuristics), inspired from nature, is developed. Finally, the proposed models and methods have been evaluated through empirical and discrete events based simulations.
Abd-Rabbo, Diala. "Beyond hairballs: depicting complexity of a kinase-phosphatase network in the budding yeast". Thèse, 2017. http://hdl.handle.net/1866/19318.