Дисертації з теми "Théorie de modes caractéristiques"
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Rabah, Mhamad Hassanein. "Design methodology of antennas based on metamaterials and the theory of characteristic modes : application to cognitive radio." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10141.
Повний текст джерелаThe rise of wireless communication systems and the big demand of high bit rate links have entailed researches to lie over new communications systems. With this diversity of wireless systems, flexibility for operating between different standards is strongly needed. Cognitive radio (CR) consist the future system that can offer this flexibility. The new features of CRs remains many challenges to their antennas. Miniaturization, isolation and bandwidth improvement, are all real needs and effective challenges. Especially when the geometry of the antenna become more complex in order to fit the terminal chassis. The use of metamaterials (MTM) has been introduced to overcome physics limitations in order to undertake these needs. The analysis of MTM in presence of radiating elements such antennas prove to be a challenge. In this thesis, an new approach to address these challenges is proposed. It is based on a modal concept using the theory of characteristic modes (TCM). It proves to be useful to analyse and design of electrically small antenna (ESA), metamaterial-inspired antennas and metamaterial-based antennas. Furthermore, the same approach is used to evaluate the antenna performances when surrounded by complex artificial materials by proposing closed formulas for the quality factor. This remains into a huge advantage in the antenna shape optimisation in the antenna industry. As a proof of concept, an extremely-wide-band antenna for underlay CR (sensing antenna) is developed using the proposed approach in order to have stable radiation pattern an high efficiency in the electrically small regime. An experimental validation of the performances of all the presented designs is also provided
Kari, Nadia. "Design methodology and modal analysis of electricallysmall antennas integrated in lossy dielectric media." Electronic Thesis or Diss., Université Gustave Eiffel, 2023. http://www.theses.fr/2023UEFL2024.
Повний текст джерелаThe demand for miniaturized wireless and autonomous communication system has climbed thanks to the wide need of wireless technologies for the monitoring of infrastructures health of our cities, in marine or in the bio-medical field … However, miniaturized antennas are generally characterized by low efficiencies and poor performances and with the presence of lossy media in the vicinity, enhancing its efficiencies becomes not straightforward task. Methods developed to enhance the performance of electrically small antennas ESAs are generally focused on one of the antenna key parameters since there is a compromise trade-off between the size, bandwidth, impedance matching and radiation efficiency. Most of these methods require trial and error and rely on understanding the physical mechanism of the ESA. Moreover, they are limited to canonical structures. On the other hand, there are methods based on the evaluation of the net energy stored in the near field region. By minimizing this stored energy, the quality factor can be enhanced and the radiation mechanism can be improved. These methods are principally based on the use of modal analysis that decompose the surface current response into modes and to extract the eigenvalues and eigenvectors of each mode. It has also been shown that the use of the artificial materials known as metamaterials can play a key role in energy compensation (magnetic coupled to electrical energy and vice versa). It could enhance efficiency, thus mitigating power effects. To date, these methods have been proposed for ESAs radiating in free space.The aim of this thesis is therefore to propose a general method for designing, analyzing andimproving ESAs radiating into lossy media. This work is based on the evaluation of the netstored energy method and the use of the metamaterials for mitigating the effects of losses.Modal methods are also investigated thanks to their useful and powerful metrics for analyzing the electromagnetic response of the structure in the near and far-field regions. The Expansion Eigen Method EEM is used to evaluate the different metrics such as the eigenmodes, eigencurrents and net stored energy to have a full information about the electromagnetic response of the antenna when it is placed in lossy media. The multi-layer substrate model is used to design the surrounding environment and each layer has the dielectric properties that correspond to the host bodies while keeping the 3D radiating structure. The use of the multi-layer substrate model is to avoid the time consuming issue of classical 3D methods. The proposed generic method show usefulness for designing and analyzing of parasitic metamaterials systems to enhance electrically small antennas in complex and lossy media
Cognault, Aurore. "Caractérisation de SER Basse Fréquence et Modes Caractéristiques." Phd thesis, Ecole Centrale Paris, 2009. http://tel.archives-ouvertes.fr/tel-00453298.
Повний текст джерелаButowiez, Jean-Yves. "Classes caractéristiques en K-théorie complexe modulo p." Nantes, 1996. http://www.theses.fr/1996NANT2013.
Повний текст джерелаVahlas, Aris. "Matrices quantiques : Produits et équations caractéristiques." Aix-Marseille 2, 2003. http://www.theses.fr/2003AIX22033.
Повний текст джерелаJalinière, Pierre. "Arithmétrique en différentes caractéristiques." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066113/document.
Повний текст джерелаIn this thesis, we present three independent works in cryptography, p-adic Hodge theory and Numerical analysis.First we present several algorithms to solve the discrete logarithm in several characteristic finite fields. We are particularly interested with the determination of classes of polynomial functions with small coefficients.The second part of the thesis deals with one of the major object of p-adic Hodge theory. We present a multi-variable version of Breuil-Kisin modules where the Lubin-Tate tower replaces the classical cyclotomic tower. He third proposes two numerical schemes for the modelisation of desorption of shale gaz
Leroy, Claude. "Approche algébrique de la théorie des modes locaux." Dijon, 1991. http://www.theses.fr/1991DIJOS010.
Повний текст джерелаFieux, Etienne. "Classes caractéristiques en KK-théorie de C*-algèbres avec opérateurs." Toulouse 3, 1990. http://www.theses.fr/1990TOU30225.
Повний текст джерелаAounil, Ismail. "Classes caractéristiques d'une opération en homologie cyclique." Toulouse 3, 1992. http://www.theses.fr/1992TOU30020.
Повний текст джерелаChéritat, Véronique. "Les modes d'évolution de la théorie générale du contrat." Orléans, 2004. http://www.theses.fr/2004ORLE0006.
Повний текст джерелаLaghrouche, Salah. "Commande par modes glissants d'ordre supérieur : théorie et applications." Nantes, 2004. http://www.theses.fr/2004NANT2115.
Повний текст джерелаCaroff, Nathalie. "Caractéristiques de l'équation d'Hamilton-Jacobi et conditions d'optimalité en contrôle optimal non linéaire." Paris 9, 1994. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1994PA090005.
Повний текст джерелаJaafar, Hussein. "Antennes miniatures, large bande et superdirectives à charges optimisées par l'analyse des modes caractéristiques." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S031/document.
Повний текст джерелаThe rapid evolution in the wireless communication systems requires more miniaturization of various electronic components in addition to the major element of the wireless technology: the antenna. In this case, an antenna occupying a limited space should be miniaturized in order to operate at the desired communication bands. However, as the electrical size of the antenna decreases, its performance degrades dramatically and it becomes limited in bandwidth, efficiency, and directivity. Classical size reduction techniques with material loading and geometry shaping of the antenna suffer from narrow bandwidth and low radiation efficiency. On the other hand, attempts to increase the directivity of small antennas using superdirective arrays are also associated with low radiation efficiency and very narrow bandwidth. To overcome these drawbacks, we propose boosting the performance of compact antennas using embedded reactive loads. By properly placing loads (active or passive) inside the antenna, it is possible to control the currents to significantly enhance the antenna performance in terms of bandwidth and directivity. Yet, for a successful loading criteria, it is mandatory to analyze the modes that are naturally supported by the antenna under study. These are called the characteristic modes, which provide deep physical insights about the behaviour of the antenna and its radiating modes. By combining this theory with and optimization algorithm, it becomes possible to optimally manipulate the currents inside the antenna using reactive loads to achieve wideband, superdirective and efficient designs
Labonté, Laurent. "Analyse théorique et expérimentale des principales caractéristiques du mode fondamental dans les fibres optiques microstructurées air/silice." Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/7992c535-e682-4254-a880-ec2515a1ccf5/blobholder:0/2005LIMO0023.pdf.
Повний текст джерелаThe work reported in this thesis deals with the experimental and numerical analysis of the birefringence, the chromatic dispersion and the extinction wavelength of the second mode (λc) of air-silica microstructured optical fibres (MOFs). The birefringence and the chromatic dispersion measurements are investigated in MOFs fabricated in our laboratory or by a partner from the industry (Alcatel). Different experimental setups are adapted for operating with MOFs. Experimental results are compared to simulations based on the finite element method. The very high measured birefringence of small core MOFs is attributed to the micro or nano imperfections of the structure. The large influence of the geometry of the fibre on the chromatic dispersion is also pointed out. Finally, for the first time to our knowledge, we apply to MOFs an azimuthal analysis far field analysis technique for precisely determining λc
Dupont, Christophe. "Propriétés extrémales et caractéristiques des exemples de Lattès." Phd thesis, Université Paul Sabatier - Toulouse III, 2002. http://tel.archives-ouvertes.fr/tel-00002634.
Повний текст джерелаBregeault, Vincent. "Quelques contributions à la théorie de la commande par modes glissants." Phd thesis, Ecole centrale de nantes - ECN, 2010. http://tel.archives-ouvertes.fr/tel-00560746.
Повний текст джерелаMatallah, Nassereddine. "Le traitement des surfaces paramétriques : étude depropriétés caractéristiques pour l'optimisation des algorithmes d'intersection." Toulouse 3, 1990. http://www.theses.fr/1990TOU30163.
Повний текст джерелаNicolas, Alexandre. "Ecoulements des solides amorphes : modélisation élastoplastique et théorie de couplage de modes." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY029/document.
Повний текст джерелаContrary to the case of simple fluids, a finite stress is required to initiate the flow of amorphous solids, a broad class of materials ranging from bulk metallic glasses to dense emulsions. The objective of this thesis is to model the flow of these materials in a general framework, with an emphasis on heterogeneities. In a first approach, using the liquid regime as a starting point, I have investigated to what extent inhomogeneities can be accommodated in the framework of the mode-coupling theory of rheology. A generic equation for the evolution of density inhomogeneities has been derived. At low temperatures, the flow is indeed quite heterogeneous: it consists of periods of elastic deformation interspersed with swift localised rearrangements of particles, that induce long-range elastic deformations and can thereby spark off new rearrangements. In a second approach, a model rooted in this scenario has been refined so as to reflect the interplay between the external drive and the localised rearrangements, which is at the origin of the flow curve of athermal solids. The latter has been reproduced satisfactorily. Turning to spatial correlations in the flow, we have shown that there exists no universal scaling for these correlations in elastoplastic models, although a broad class of correlation lengths scale with dot{gamma}^{ icefrac{-1}{d}} in the shear-dominated regime in d dimensions. Besides, shear localisation has been observed in diverse variants of the model, whenever blocks are durably weakened following a plastic event. Finally, we have directly compared model predictions to experimental results on the flow of dense emulsions through microchannels and to athermal molecular dynamics simulations. Spurred on by the observation of some discrepancies, we have developed and implemented a more flexible code, based on a simplified Finite Element routine, which notably provides a better account of structural disorder and inertial effects
Antoni, Mickaël. "Dynamique microscopique des plasmas : de N corps à M modes et Nq particules." Aix-Marseille 1, 1993. http://www.theses.fr/1993AIX11056.
Повний текст джерелаLiard, Quentin. "Dérivation des équations de Schrödinger non linéaires par une méthode des caractéristiques en dimension infinie." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S126/document.
Повний текст джерелаIn this thesis, we justify the mean field approximation in a general framework for bosonic systems. The derivation of mean field dynamics is known for some specific quantum states. Therefore it is natural to expect the extension of these results for a general family of normal states. The mean field approximation for bosons consists in replacing the many-body quantum problem by a non linear one, so-called Hartree problem, when the number of particles tends to infinity. We establish a general result for bosons confined or not, interacting through a singular potential. The method used is based on Wigner measures. Our contribution consists in extending the characteristics method when the velocity field associated to the Hartree equation is subcritical or critical. It complements the work of Ammari and Nier and provides a result for critical potential for the Hartree equation. We also focus on bosonic systems interacting through a multi-body potential and we prove the mean field approximation under a strong assumption on this potential. All these results essentially rely on the flexibility of Wigner measures and we can give an alternative proof of the variational mean field approximation
Moutrane, Ennajat. "Interactions de modes sphériques dans le problème de Bénard entre deux sphères." Nice, 1988. http://www.theses.fr/1988NICE4225.
Повний текст джерелаBader, Ahmed. "Quelques résultats sur la stabilisation des systèmes couplés." Besançon, 2000. http://www.theses.fr/2000BESA2032.
Повний текст джерелаRoy, Réal 1944. "Une vérification empirique de la théorie des caractéristiques des emplois appliquée aux directions d'école du Québec /." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69569.
Повний текст джерелаThe results obtained indicate that the Job Characteristics Model is not exactly the right means to study school principals' motivation. But the analysis of variance revealed some significant differences between the means of the school principals.
Khellaf-Haned, Hadja Faïza. "Autour des différents modes de représentation et de raisonnement en théorie des possibilités quantitative." Artois, 2007. http://www.theses.fr/2007ARTO0403.
Повний текст джерелаThis work is intended to provide some contributions in the framework of the representation and the reasoning on uncertain knowledge based on a non probabilistic approach: the quantitative possibilistic theory. In the field of the representation, this study has contributed to developp equivalences between a quantitative possibilistic base and a possibilistic causal networks based on the product. Moreover, it shows that the beliefs networks based on the ordinal conditioning functions op Spohn as well as the penalties bases can be naturally represented with the quantitative possibilistic bases. In the field of the reasoning, an original algorithm was developped for the inference starting from the quantitative possibilistic bases. An experimental study was also carried out thus confirming the advantages of inference tool based on possibilistic quantitative logic
Latry, Olivier. "Théorie des modes locaux dans les guides perturbés application : couplage fibre optique - photodiode PIN." Rouen, 1995. http://www.theses.fr/1995ROUE5001.
Повний текст джерелаMénacq, Bernard. "Modes d'engagement dans les fonctions de directeur d'école : rôle des caractéristiques socio-biographiques et des significations accordées à l’activité." Thesis, Toulouse 2, 2012. http://www.theses.fr/2012TOU20062.
Повний текст джерелаWe explore and analyze, in this research, patterns of teacher’s commitment who become principals. This is a personal and professional transition that takes place in a context of changing educational environment and institutional transformation.This passage of new features is often accompanied by a restructuring of identity. Beyond the action, the commitment is based on a complex and dynamic behavior, attitudes, but also processes psycho, socio-cognitive and conative.In an active and plural approach of socialization, the model of the subject and institutions interstructuration (Baubion-Broye, A., Malrieu, P. & Tap, P., 1987) which we refer, considers that beyond external influences and socio-biographical components, that is the subject who is the agent of its commitments.We show that the conducts of professional commitment are not confined to social influences or personal intentions but they are guided by the process of inter-service work. The origins of commitment refer to other areas of life and time of existence for individuals and based in particular on trade-offs of competing values and referred.Research updates a typology of socio-professional trajectories of directors into three classes, which we measure the differential influence on the direction of their commitments.Our results indicate how certain values drive behaviors and how these values are tested when in the course of professional practice, installs a sense of gap between expected, realized and prescribed.Each type of commitment appears as a dimension of life plan that articulates a singular way the aims, resources and constraints of different domains of life (family, professional, personal, social)
Esploriamo e analizziamo i coinvolgimenti di insegnanti che diventano direttori scolastici. Si tratta di una transizione personale e professionale che si svolge in un contesto di evoluzione educativa e di trasformazione istituzionale. Questo passaggio a nuove funzioni coincide spesso con una ristrutturazione dell'identità. Oltre all’ azione, l'impegno si basa non solo su un insieme complesso e dinamico dei comportamenti, ma anche su dei processi psico-affettivi , socio-cognitivi e conativi. In un approccio attivo e plurale della socializzazione, il modello dell’ interstructurazione del soggetto e delle istituzioni (Baubion-Broye, A., Malrieu, P. & Tap, P., 1987) alle quali ci riferiamo, ritiene che al di là di influenze esterne e di elementi socio-biografici, è al soggetto che spetta la decisione del suo impegno. Mostriamo che le linee di impegno professionale non si limitano solo alle influenze sociali o alle intenzioni personali, ma sono anche guidate dai processi d’inter-significato del lavoro. Le origini di questo impegno provengono da altri settori della vita e dai tempi di esistenza degli individui e si basano particolarmente sugli arbitraggi di valori e di ambizioni rivali. La ricerca evidenzia una tipologia delle traiettorie socio-professionali dei direttori in tre classi, di cui si misura l'influenza differenziale sulla direzione degli impegni assunti. I nostri risultati mostrano che certi valori orientano i comportamenti e che questi valori vengano testati quando, nel corso della pratica professionale, si installa un senso di discrepanza fra ciò che è atteso, previsto e realizzato. Ogni tipo di impegno appare comme una dimensione di un progetto di vita che organizza in modo singolare gli obiettivi, le risorse e gli obblighi dei diversi settori della vita (familiare, professionale, personale, sociale)
Dens la nosta recerca, qu’esploram e qu’analisam modos d’engagemen del regents que basan directùrs d’escola. Que pot estar ua transicion personela e professionella qu’arriva dens un contexto d’evolucion de l’educacion e de transformacion institucionela.Aquet passage dens naoeras foncions que va taben dabt ua restructuracion de l’identitat. Meij que l’accion, l’engagemen qu’ei contenut dens un ensemblo complexo e dinamico de comportaments, d’attitudas e taben de procesus psico-affectifs, sociocognitifs e conatifs.Dens ua approcha activa e pluriela de la socialisacion, lo modelo de l’interstructuracion do sujet dabt las institucions (Baubion-Broye, A., Malrieu, P. & Tap, P., 1987), qu’ei aquiu la nosta referença teorica, considera que meij qu’influenças externas e composantas socio-biograficas, qu’ei lo sujet qui, eht tot sol, megna lo son engagemen.Que mushem que los comportaments d’engagemen profesionel ne venguen pas sulamen d’ influenças socialas o d’intencions personalas ; au loc de quò que son guidadas per processus d’intersignificacion do travalh. Las originas de l’engagemen qu’es referan a d’autis dòmanis de vita et temps d’existença per los sujets e que dependan d’arbitrajos de valors e d’ambicions concurentas.La nosta estudia que presenta ua tipologia de trajectorias socioprofessionalas dos regents en trés classas, per cadùa que mesurem taben l’influença diferenciala sur l’orientacion do sons engagemens.Los nostos resultats que mushent cum caocas valors orientan los comportemens e cum aqueras valors son boutades a l’eprova quan, pendan lo travalh, qu’arrivo un sentimen de descalage entre ço qui ei attendut, prescrit et heit.Cado tipò d’engagemen qu’ei la dimension d’un projet de vita qui compren las ambicions, las resorças e las obligacions dos diferents dòmanis (familial, profesionel, personel, social)
Lognonné, Philippe. "Modélisation des modes propres de vibration dans une Terre anélastique en hétérogène : théorie et applications." Paris 7, 1989. http://www.theses.fr/1989PA077244.
Повний текст джерелаBot, Patrick. "Modes d'instabilités secondaires et supérieures dans le systèmes de Taylor-Dean." Le Havre, 1998. http://www.theses.fr/1998LEHA0012.
Повний текст джерелаJacqus, Gary. "Étude des caractéristiques acoustiques des matériaux alvéolaires utilisés pour la construction de parois dans le bâtiment." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/3111/.
Повний текст джерелаHollow bricks are widely as building structural elements, mainly for their attractive thermal insulation properties. However, because of their high thickness, inhomogeneity and strong anisotropy, the physical laws commonly used in building acoustics do not provide accurate predictions in the case of these materials. To solve this problem, a simplified semi-analytical approach is proposed to compute sound transmission through hollow brick walls. A homogenised vibratory model is derived and compared to various test data. In this formalism, the wall is treated as a thick orthotropic and homogenised plate. An efficient numerical homogenisation process, based on the finite element method, is used to get the equivalent elastic constants of one brick block. Accelerometrics and an acoustical holography technique are then applied to study the vibrationnal properties of a brick wall in the range [100Hz, 5kHz]. The last part of this work is devoted to the optimization of the acoustic behaviour of hollow brick walls. First, several parametric studies are leaded to higlight the relevant physical parameters for the improvement of the acoustic properties. Besides, the concept of irregularity is introduced. The effect of spatial dispersion of the geometrical irregularities on sound insulation is discussed
Pitault-Charbonnel, Anne-Elisabeth. "Les différents modes de fourniture des biens collectifs et leurs conséquences." Paris 1, 1999. http://www.theses.fr/1999PA010062.
Повний текст джерелаVernet, Raphaël. "Approche mixte théorie / expérimentation pour la modélisation numérique de chambres réverbérantes à brassage de modes." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00691124.
Повний текст джерелаBen, Souf Mohamed Amine. "Approche stochastique à base de modes d'ondes : théorie et applications en moyennes et hautes fréquences." Thesis, Ecully, Ecole centrale de Lyon, 2012. http://www.theses.fr/2012ECDL0035/document.
Повний текст джерелаThe prediction of dynamic behavior of structures is an important task in the design step of any mechanical product. There are many factors affecting the choice of the used methods. For a dynamic system, the frequency band under study is one of the important parameters since for each frequency range exists its appropriate approach which can be quickly inapplicable in other domains. For example, the high frequency methods are very limited in the lower part of the spectrum. Similarly, the so-called low-frequency methods become numerically inefficient if it goes up in frequency range. The mid-frequencies then represent the high-frequencies for global and low frequencies for local methods. Knowing that uncertainties play an important role on the vibro-acoustics behavior in mid-frequencies, the presented work is a contribution to the research approach, with inexpensive computing time, allowing the extension of a local method, called ’the wave finite element method’, in this frequency band. These contributions consist in taking into account uncertainties in the studied system to evaluate the dispersion of all parameters (spectral, diffusion, dynamics, etc.) and their effects on the global response (kinematic and energetic) of the structure. The presented work can be divided into two main parts. The first one involves the development of an explicit and direct formulation describing the dispersion of different parameters; this part is based on the first-order perturbation method. The second part is a generalization of the first one; indeed, using the chaos polynomial projection of all random variables allows a more general assessment of the effects of uncertainties on the dynamics of periodic structure in mid-frequency range
Marhraoui, Nouzha. "Résolution de l'équation de transport par des méthodes nodales et de caractéristiques." Besançon, 1987. http://www.theses.fr/1987BESA2017.
Повний текст джерелаGrassi, Gabriele. "Conception de nouveaux schémas multigrilles appliqués à la méthode des caractéristiques pour la résolution de l'équation du transport des neutrons." Evry-Val d'Essonne, 2006. http://www.theses.fr/2006EVRY0014.
Повний текст джерелаThis dissertation is based upon our doctoral research which dealt with the conception and development of new non-linear multigrid techniques for the Method of the Characteristics (MOC) within the TDT code. Here we focus upon a two-level scheme consisting of a fine level on which the neutron transport equation is iteratively solved using the MOC algorithm, and a coarse level defined by a more coarsely discretised phase space on which a low-order problem is considered. The solution of this problem is then used in order to correct the angular flux moments resulting from the previous transport iteration. A flux-volume homogenisation procedure is employed to evaluate the coarse-level material properties after each transport iteration. This entails the non-linearity of the methods. According to the Generalised Equivalence Theory (GET), additional degrees of freedom are introduced for the low-order problem so that the convergence of the acceleration scheme can be ensured. We present two classes of non-linear methods: transport-like methods and diffusion-like methods. Transport-like methods consider a homogenised low-order transport problem on the coarse level. This problem is iteratively solved using the same MOC algorithm as for the transport problem on the fine level. Discontinuity factors are then employed, per region (DFs) or per surface (SDFs), in order to reconstruct the currents evaluated by the low-order operator, which ensure the convergence of the acceleration scheme. On the other hand, diffusion-like methods consider a low-order problem inspired by diffusion. We studied the non-linear Coarse Mesh Finite Difference (CMFD) method, already present in literature, in the perspective of integrating it into the TDT code. Further, we developed a new non-linear method on the model of CMFD. From the latter, we borrowed the idea to establish a simple relation between currents and fluxes in order to obtain a problem involving only coarse fluxes. Finally, those non-linear methods have been extended to the multigroup problem developing an acceleration for the outer iterations. Tests concerning cases of practical interest have been performed for all the non-linear methods. Results are presented and discussed
Lebreton, Annie. "Caractéristiques génomiques du genre fongique Mucor et évolution adaptative liée à différents modes et conditions de vie au sein du genre." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0098/document.
Повний текст джерелаThe genus Mucor belongs to the phylum Mucoromycota; a group that derived from the lineages that diverged early in the evolution of fungal species (early diverging lineages). These groups have been less well studied and are less well understood in comparison to Ascomycetes and Basidiomycetes. The genus Mucor is composed of saprophytic species, but also encompasses species with diverse lifestyles.For example, it includes plant endophytes (such as M. endophyticus) or opportunistic animal pathogens (such as the thermophilic species M. circinelloides or M. indicus). The genus is ubiquitous but there are some associations with specific habitats which seem to indicate specialisation. The aim of this thesis is to better understand the genetic potential of the genus Mucor in particular, to decipher how it maintains this ubiquitous lifestyle, its capacity to adapt to diverses habitats and to better understand the existence within the genus of species that may have undergone specialization allowing them to preferentially or exclusively colonise certain habitats, such as cheese. In order to achieve this, we have performed comparative transcriptomic and genomic studies in order to determine the main structural and functional characteristics of the Mucor genomes, identify similarities among the species studied and also assess whether there exist specific genetic associations with lifestyle/habitat and determine whether the species frequently found in cheese (in particular those species considered as technological) harbour imprints of adaptation or even domestication
Huang, Yuliang. "Contributions à la géométrie algébrique imparfaite en caractéristique positive." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S043/document.
Повний текст джерелаThis thesis work, consisting of four parts, is devoted to the study of algebraic geometry in mixed and positive characteristics. In the first part, motivated by a conjectural ramification theory for inseparable torsors, we study the maximal model of a torsor over a local field, which is a generalization of integer rings in classical ramification theory. We prove the maximality and functoriality of maximal models, and calculate them explicitly for some finite flat group schemes of order p. The second part is a joint work with Giulio Orecchia and Matthieu Romagny. We study perfection of algebras and coperfection of algebraic spaces and stacks. We prove that the space of connected components provides the coperfection of an algebraic space, and it represents the colimit of relative Frobenii. In the case of algebraic stacks, we construct the étale fundamental pro-groupoid, and prove that it provides the coperfection, and it represents the colimit of relative Frobenii in Deligne-Mumford case. In the third part, we prove some results on flatness and representability of moduli spaces of torsors under certain group schemes, which naturally arise from the proper moduli space of Galois p-covers (stable p-torsors). We also discuss the relation with generalized Jacobians of open curves. In the last part, we are interested in a new kind of nonarchimedean analytic geometry, with valuations on totally ordered commutative monoids. We study some examples from schemes and adic spaces
Lazès, Julie. "Conflictualité, distribution et instabilité macroéconomique. Comportements rentiers et modes de régulation en Argentine." Amiens, 2012. http://www.theses.fr/2012AMIE0052.
Повний текст джерелаLegrand, Claude. "Dynamique stratégique des organisations sportives et modes de régulation." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2010. http://tel.archives-ouvertes.fr/tel-00562313.
Повний текст джерелаArquier, Rémi. "Une méthode de calcul des modes de vibrations non linéaires de structures." Aix-Marseille 2, 2007. http://theses.univ-amu.fr.lama.univ-amu.fr/2007AIX22037.pdf.
Повний текст джерелаThe aim of this thesis is to evaluate new theoric and numeric tools for non linear modes computation of structures with geometric non linearity discretised by the finite element method. The invariant surface which caracterises the non linear mode is defined with a family of periodic orbits solution of the equation of motion. Each orbit is time discretised (Newmark or Simo scheme) and formulated with a global system containing all unknows for every time steps, this is the simultaneous method, by opposition with the classic shooting method. The orbit family solution of the global system is obtained with the Asymptotic Numerical Method. Some variations around the ANM are also adressed. We introduced new approach to control continuation around a bifurcation point by adding a perturbation to the non linear system. We also present a software, MANLAB, allowing interactive continuation of complex bifurcation diagrams, which is applied to the family of periodic orbits
Khuat-Duy, David. "Formule des traces semi-classique pour une énergie critique et construction de quasi-modes à l'aide d'états cohérents." Paris 9, 1996. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1996PA090045.
Повний текст джерелаMasiello, Emiliano. "Résolution de l'équation du transport des neutrons par les méthodes des éléments finis et des caractéristiques structurées appliquées à des maillages hétérogènes." Evry-Val d'Essonne, 2004. http://www.theses.fr/2004EVRY0012.
Повний текст джерелаThe principal goal of this manuscript is devoted to the investigation of new a type of heterogeneous mesh adapted to the shape of the fuel pins (fuel-clad-moderator). The new heterogeneous mesh guarantees the spatial modelling of the pin-cell with a minimum of regions. Two methods are investigated for the spatial discretization of the transport equation: the discontinuous finite element method and the method of characteristics for structured cells. These methods together with the new representation of the pin-cell result in an appreciable reduction of calculation points. They allow an exact modelling of the fuel pin-cell without spatial homogenisation. A new synthetic acceleration technique based on an angular multigrid is also presented for the speed up of the inner iterations. These methods are good candidates for transport calculations for a nuclear reactor core. A second objective of this work is the application of method of characteristics for non-structured geometries to the study of double heterogeneity problem. The letters is characterized by fuel material with a stochastic dispersion of heterogeneous grains, and until now was solved with a model based on collision probabilities. We propose a new statistical model based on renewal-markovian theory, which makes possible to take into account the stochastic nature of the problem and to avoid the approximations of the collision probability model. The numerical solution of this model is guaranteed by the method of characteristics
Santandrea, Simone. "Qualification physique et améliorations du modele numérique d'une méthode des caractéristiques pour la résolution de l'équation du transport des neutrons dans des maillages non structurés." Evry-Val d'Essonne, 2001. http://www.theses.fr/2001EVRY0008.
Повний текст джерелаCherrid, Hadia. "Commande et observateur par modes glissants d'ordre un et deux : application aux systèmes robotisés." Versailles-St Quentin en Yvelines, 2001. http://www.theses.fr/2001VERS0033.
Повний текст джерелаIn the control of robotics systems, in order to synthesize control laws, all system state is necessary. Nevertheless, generally, only positions are measured. Their times derivatives are often either not available or contained noise. Therefore, it becomes essential to study and use observers for the control law. As for nonlinear systems, the separation principle is not applicable. We are interested by synthesizing the control and also the observer. Witch will guarantee the stability of the system as well as good performances. We have focused our work on the control of robot manipulators with electric and pneumatic actuators. We have chosen sliding mode technique in order to ensure robustness of the system regarding parameter uncertainties. We have introduced an additional adaptive law to make an enhancement : completely free oneself from the structure of the model. This guaranties an excellent robustness regarding structural errors. At last, to overcome the problem of chattering control in the two precedent schemes, we have introduced the second order in sliding mode to synthesize the controller and observer, in the case of variable systems. The thesis includes a recapitulative and comparative table, to choose the controller and observer strategies for a most number of lagrange’s systems. For each proposed control and observer schemes, we have presented simulation and experimental results which validate the theoretical study
Vergnerie, Cédric. "La théorie des caractéristiques dans les Vorlesungen über die Theorie der algebraischen Gleichungen de Kronecker : la fin du cycle d’idées sturmiennes ?" Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC238/document.
Повний текст джерелаIn her book Corps et Modèles, Hourya Sinaceur presented Kronecker’s theory of characteristics as the end of a “cycle of Sturmian ideas”, making it a step in history of the algebraization of Sturm’s theorem. However, this theory is often also introduced as the starting point of some of the early works of topology of the very end of the nineteenth century. In this PhD thesis, I will describe how these two stories are connected in Kronecker’s theory. To achieve this, I used material which has seldom been discussed before : the manuscripts of the courses that Kronecker gave at the University of Berlin between 1872 and 1891 on the Theory of algebraic equations. I begin with the presentation of these manuscripts, their contents and their writing contexts. I then look more closely at Kronecker’s rework of the theorem of Sturm and show that the theory of characteristics is not only an algebraic extension of this theorem but also that it is transformed in order to provide some of the analytic tools that Poincaré will use for the construction of his Analysis Situs. The exposition of the theory of characteristics in his courses is an opportunity for Kronecker to take up three of the four demonstrations from Gauss of the fundamental theorem of algebra, and I will show how, in Kronecker’s practice, the very notion of root is questioned
Jouvaud, Camille. "Etude et application en micro-onde de l'hybridation de modes dans des systèmes localement résonants." Paris 7, 2013. http://www.theses.fr/2013PA077228.
Повний текст джерелаDevelopment of photonic media, and more recently of metamateriais has drawn a new interest in acoustic and electronnagnetic wave control. In this thesis, we propose an original approach of periodic lattice built with sub-wavelength resonators. Using electrodynamics analysis, we highlight collective phenomena of hybridization due to electromagnetic interactions. A model based on an approximation of resonators as electric and magnetic dipoles allows an analytical study. This approach must, on the one hand, be complementary to exciting models used to describe band gap apparition in locally periodic medium; and on the other hand, allow quantifying radiation properties of finite size media. This work has been applied to the design of a miniature antenna whose radiation pattern is controllable both in frequency and directivity. A sub-wavelength imaging device was also developed. It is based on the control of Iocalized eigen-modes. Finally, hybridization properties of modes between half wavelength resonators are exploited to design an antenna dedicated to Magnetic Resonance Imaging. This antenna is used to generate and control the distribution of the radio-frequency magnetic field in the imaging volume which is a major challenge with the field sise of MR1
Desfossés, Nadia. "Modélisation de l'impact du revenu sur la demande de biens ayant des caractéristiques environnementales supérieures." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/26888/26888.pdf.
Повний текст джерелаChédru, Marie. "Impact de la motivation et des caractéristiques individuelles sur la performance : application dans le monde académique." Phd thesis, Institut National des Télécommunications, 2012. http://tel.archives-ouvertes.fr/tel-00789718.
Повний текст джерелаPlot, Virginie. "Caractéristiques maternelles, performances et stratégies de reproduction des tortues marines de Guyane." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00867096.
Повний текст джерелаNicolas, Bruno. "Contribution à la commande des convertisseurs statiques : définition de lois de commutation à l'aide de la théorie des modes glissants." Toulouse, INPT, 1996. http://www.theses.fr/1996INPT064H.
Повний текст джерелаLihoreau, Bertrand. "Réfrigérateur thermoacoustique "compact" : modélisation, conception, évaluation." Le Mans, 2002. http://cyberdoc.univ-lemans.fr/theses/2002/2002LEMA1014.pdf.
Повний текст джерелаIn recent years, there has been a strong motivation for designing new thermoacoustic refrigerators involvong smaller dimensions and lower power consumption. Attempts to develop practical devices have been concentrated on both reducing th escale of the classical refrigerators and adapting piezoelectric sources. But the need for providing advances in modelling and designing miniaturized systems arises when dealing with the heat transfert from microelectronic components. Therefore, the aim of the work done on this subject is threefold : -i- To invistigate analytically the behaviour of the coupling between piezoelectric sources and thermoacoustic resonators, using a revisited description for the acoustically loaded piezoelectric system which conveys significant improvements and new (unexpected) results, -ii- To derive a method, extending analytical results available in the literature, to identify more deeply the parameters which govern the optimal behaviour of the core of the thermoacoustic systems (here the highest temperature gradient allowed in the stack), -iii- To design a miniaturized compact thermoacoustic refrigerator using the theoretical results obtained from the method mentioned above, and to show agreements and discrepancies between theoretical and experimental results. Requirements that have to be taken into account in the design of new kind of miniaturized compact thermoacoustic refrigerators (using MEMS techniques for the core and adapted piezoelectric transducers) can be adressed from results obtained and the ideas conveyed in this work