Dissertations / Theses on the topic 'Calcul perturbatif'
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VILANOVE, HELENE. "Utilisation des bases de representation par variables discretes dans le calcul non perturbatif des spectres de vibration-rotation des molecules triatomiques : application au dioxyde d'azote." Reims, 1996. http://www.theses.fr/1996REIMS030.
Full textPeigne, Stéphane. "Calcul perturbatif d'observables du plasma de quarks et de gluons : comportement infrarouge des theories de jauge a haute temperature. effets coherents dans un milieu non abelien." Paris 11, 1995. http://www.theses.fr/1995PA112156.
Full textPascalie, Romain. "Tenseurs aléatoires et modèle de Sachdev-Ye-Kitaev." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0099.
Full textThis thesis treats different aspects of random tensors. In the first part of the thesis, we study the formulation of random tensors as a quantum field theory called tensor field theory (TFT). In particular we derive the Schwinger-Dyson equations for a tensor field theory with an U(N)-invariant melonic quartic interactions, at any tensor rank. The correlation functions are classified by boundary graphs and we use the Ward-Takahashi identity to derive the complete tower of exact, analytic Schwinger-Dyson equations for correlation functions with connected boundary graph.We then analyse the large N limit of the Schwinger-Dyson equations for rank 3 tensors. We find the appropriate scalings in powers of N for the various terms present in the action. This enable us to solve the closed Schwinger-Dyson equation for the 2-point function of a TFT with only one quartic melonic interaction, in terms of Lambert's W-function, using a perturbative expansion and Lagrange-Bürmann resummation. Higher-point functions are then obtained recursively.In the second part of the thesis, we study the Sachdev-Ye-Kitaev (SYK) model which is closely related to tensor models. The SYK model is a quantum mechanical model of N fermions who interact q at a time and whose coupling constant is a tensor average over a Gaussian distribution. We study the effect of non-Gaussian average over the random couplings in a complex version of the SYK model. Using a Polchinski-like equation and random tensor Gaussian universality, we show that the effect of this non-Gaussian averaging leads to a modification of the variance of the Gaussian distribution of couplings at leading order in N. We then derive the form of the effective action to all orders and perform an explicit computation of the modification of the variance in the case of a quartic perturbation.In the third part of the thesis, we analyse an application of random tensors to non-linear resonant system. Focusing on a typical model similar to the SYK model but with bosons instead of fermions, we perform a Gaussian averaging both for the tensor coupling between modes and for the initial conditions. In the limit when the initial configuration has many modes excited, we compute the variance of the Sobolev norms to characterise how representative the averaged model is of this class of resonant systems
Kneur, Jean-Loic. "Calculs perturbatifs variationnellement améliorés en théorie des champs; calcul du spectre et contraintes sur le modèle supersymétrique standard." Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2006. http://tel.archives-ouvertes.fr/tel-00265720.
Full textSimon, Yehudi. "Resommation pour des processus de QCD à l'aune du Run 3 du LHC." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS470.
Full textThe predictions derived from the Standard Model of particle physics allow to compare theory with experimental mesurements. As the LHC is currently running its third data taking campain, it is of particular interest in the context of LHC physics. This comparison is crucial both in the context of precision measurements, to detect possible deviations from the Standard Model, and for direct searches for new particles. The recent progress in experimental measurements, particularly with Run 3 of the LHC, calls for improvements in theoretical predictions related to rarer and more complex processes. To achieve this goal, increasing the number of perturbative orders taken into account in the calculations is not the only solution. Techniques such as soft gluon threshold resummation allow terms at all orders to be taken into account by exponentiation. This typically reduces the theoretical errors bars and improves the accuracy of the results. In this thesis, we focused on the application of resummation to processes involving QCD corrections at the subdominant order, firstly in the context of exotic lepton production, and secondly in quark top physics
Iacomi, Marius. "Calculs non-perturbatifs en théorie des champs bidimensionnelle." Montpellier 2, 1997. http://www.theses.fr/1997MON20240.
Full textGruey, Louis Jules. "Sur le calcul numérique des perturbations des petites planètes au moyen des quadratures." Paris : Bibliothèque universitaire Pierre et Marie Curie (BUPMC), 2009. http://jubil.upmc.fr/sdx/pl/toc.xsp?id=TH_000278_001&fmt=upmc&idtoc=TH_000278_001-pleadetoc&base=fa.
Full textPérigaud, Ernest Louis Antoine. "Exposé de la méthode de Hansen pour le calcul des perturbations spéciales des petites planètes." Paris : Bibliothèque universitaire Pierre et Marie Curie (BUPMC), 2009. http://jubil.upmc.fr/sdx/pl/toc.xsp?id=TH_000291_001&fmt=upmc&idtoc=TH_000291_001-pleadetoc&base=fa.
Full textZézé, Djédjé Sylvain. "Calcul de fonctions de forme de haut degré par une technique de perturbation." Thesis, Metz, 2009. http://www.theses.fr/2009METZ056S.
Full textMost problems of physics and mechanics lead to partial differential equations. The many methods that exist are relatively low degree. In this thesis, we propose a method of very high degree. Our idea is to increase the order of interpolation function via a perturbation technique to avoid or reduce the difficulties caused by the high cost operations such as integrations. In dimension 1, the proposed technique is close to the P-version finite elements. At a basic level, approximates the solution by a power series of order p. In the case of a linear equation of order 2, the local resolution can build an element of degree, with two degrees of freedom per element. For nonlinear problems, a linearization of the problem by Newton's method is needed. Tests involving linear and nonlinear equations were used to validate the method and show that the technique has a similar convergence in the p-version finite elements. In dimension 2, the problem is discretized through reorganizing polynomials in homogeneous polynomials of degree k. After a definition of variables called principal and secondary combined with a vertical scanning field, the problem becomes a series of 1D problem. A collocation technique allows to take into account the boundary conditions and coupling conditions and determine the solution of the problem. The collocation technique coupled with the least-squares enabled to improve the initial results and has made more robust the perturbation technique
Coine, Clément. "Continuous linear and bilinear Schur multipliers and applications to perturbation theory." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD074/document.
Full textIn the first chapter, we define some tensor products and we identify their dual space. Then, we give some properties of Schatten classes. The end of the chapter is dedicated to the study of Bochner spaces valued in the space of operators that can be factorized by a Hilbert space.The second chapter is dedicated to linear Schur multipliers. We characterize bounded multipliers on B(Lp, Lq) when p is less than q and then apply this result to obtain new inclusion relationships among spaces of multipliers.In the third chapter, we characterize, by means of linear Schur multipliers, continuous bilinear Schur multipliers valued in the space of trace class operators. In the fourth chapter, we give several results concerning multiple operator integrals. In particular, we characterize triple operator integrals mapping valued in trace class operators and then we give a necessary and sufficient condition for a triple operator integral to define a completely bounded map on the Haagerup tensor product of compact operators. Finally, the fifth chapter is dedicated to the resolution of Peller's problems. We first study the connection between multiple operator integrals and perturbation theory for functional calculus of selfadjoint operators and we finish with the construction of counter-examples for those problems
Ait-Amirat, Youcef. "Contribution à la théorie de la structure des systèmes en automatique : application au découplage et au rejet de perturbations." Lyon 1, 1994. http://www.theses.fr/1994LYO10179.
Full textHESS, OLIVIER. "Approche perturbative des interactions moleculaires : calcul ab initio et monte carlo quantique des composantes de l'energie d'interaction." Paris 6, 1989. http://www.theses.fr/1989PA066242.
Full textHarvey, Emily Paige. "Analysing mathematical models of intracellular calcium dynamics using geometric singular perturbation techniques." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/10814.
Full textDumas, Jean-Guillaume. "Contributions au calcul exact intensif." Habilitation à diriger des recherches, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00514925.
Full textMorinière, Maxime. "Formalismes et méthodes pour le calcul de la réponse linéaire des systèmes isolés." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY096/document.
Full textThe linear response on the time-dependent density functional theory is studied in the wavelets formalism used in the BigDFT code, that allows the representations of electronic wave-functions on a simulation grid in real space. The goal of this study is to determine a reference excitation spectrum for a given system and exchange-correlation potential.It appears that only one part of the spectrum can be easily brought to convergence with respect to the input parameters of BigDFT, which are the simulation grid extension and the number of unoccupied continuum orbitals considered in the spectrum calculation. The energy of the last unoccupied orbital used actually proves to be more important as a parameter than this number of unoccupied orbitals. This is justified by the study of the completeness of the basis sets made of the ground state orbitals of the system. This gives another point of view regarding spectrum obtained by using the Gausian basis sets formalism, as the one implemented in the code NWChem.As to the convergence of the spectrum at higher energy, concerning transitions between occupied orbitals and unoccupied orbitals of the continuum, the hope for a convergence faces the problem of the continuum collapse. One therefore has to think of another way of retrieving the data contained in this continuum.The resonant states formalism, whose foundations were laid in the first half of the 20th century, is very encouraging in this regard. A preliminary study in the case of the one-dimension square well potential is therefore presented. The first step consisted in the determination of these resonant states, whose energies and wavefunctions are complex valued in general. Their normalization was also clearly defined. It is then shown, under certain conditions, that the basis set formed by the eigenstates of this potential, including the continuum states, can be efficiently replaced by a discrete and complete basis set made of resonant states. Numerical applications also show that these states can also be advantageously used to define the Green's function or even compute the time propagation of a wavepacket
Braconnier, Thierry. "Sur le calcul des valeurs propres en précision finie." Nancy 1, 1994. http://www.theses.fr/1994NAN10023.
Full textLoss, Omar. "Perturbation of pH and calcium signalling as a means to prevent Aspergillus fumigatus infection." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506048.
Full textFaiez, Sorkhabi Mohammad Reza. "Calcul théorique du couplage spin-orbite et du tenseur G dans les systèmes moléculaires." Nancy 1, 1992. http://www.theses.fr/1992NAN10070.
Full textPagliarani, Stefano. "Metodi perturbativi per E.D.P e applicazioni in finanza matematica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amslaurea.unibo.it/1392/.
Full textVoisin, Christophe. "Contribution au calcul du terme d'induction dans les potentiels d'interactions moléculaires pour la modélisation des polypeptides." Nancy 1, 1991. https://tel.archives-ouvertes.fr/tel-00175114.
Full textClaude, Bertille. "Calcul des vibrations non linéaires d’une structure composite en contact avec un fluide par la Méthode Asymptotique Numérique : application à la vibroacoustique." Thesis, Lorient, 2018. http://www.theses.fr/2018LORIS516/document.
Full textNoises and vibrations control is a common objective in the industrial field. Whether it is a question of comfort or safety, the fields of application are numerous and varied: transport, building, civil and military engineering… In this thesis, a vibroacoustics interior problem with fluid-structure coupling is studied. A cavity filled of fluid whose walls are made of a sandwich viscoelastic structure is considered. The numerical difficulties associated with this model relate to the non-linearity of the viscoelastic material and the properties of the matrix operators used (conditioning, non-symmetry). The calculation of the vibrations of the coupled dissipative system requires an initial value, chosen as the solution to the conservative problem. Since this solution is difficult to determine, two eigenvalue algorithms based on the Asymptotic Numerical Method (ANM) are proposed to solve the problem of free vibrations of the conservative system. Combining high order perturbation and continuation techniques, ANM transforms the initial non-linear problem into a set of linear problems that are easier to solve. The solutions obtained are then used as the initial point to determine the free vibrations of the dissipative problem. A high order Newton solver, based on homotopy and perturbation techniques, is developed to solve this problem. Finally, the forced harmonic response of the damped system is computed. For all the configurations tested, the results obtained show improved numerical performance compared to the methods conventionally used (Arpack solver, Newton algorithm…)
Martin, Alexandre. "Calcul de la réponse à la déformation et au champ électrique dans le formalisme "Projector Augmented-Wave". Application au calcul de vitesse du son de matériaux d'intérêt géophysique." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1034/document.
Full textThe internal composition of our planet is a large topic of study and involves many scientific disciplines. The extreme conditions of pressure and temperature prevailing inside the core (consisting primarily of iron and nickel) and the mantle (consisting mainly of perovskites) make the determination of the exact compositions very difficult. This thesis contributes to recent studies whose aim is to determine more accurately the chemistry of these minerals. Its purpose is the development of a tool for the calculation of seismic wave velocities within methods based on ab-initio simulations. These velocities are calculated from the full elastic tensor, including the atomic relaxation and induced changes in the crystal field. We use the approach of the density functional perturbation theory (DFPT) to eliminate numerical uncertainties induced by conventional methods based on finite differences. We combine this approach with the « Projector Augmented-Wave » (PAW) formalism that takes into account all the electrons of the system with a low computational cost. We apply the method on core and mantle materials and we determine the effects of various lights elements (Si, S, C, O and H) on the seismic wave velocities of pure iron, as well as the effect of aluminum in the perovskite MgSiO3
Sbai, Abdellah. "Contribution au calcul du flottement d'un avion de transport subsonique dans le domaine transsonique." Toulouse, ENSAE, 1990. http://www.theses.fr/1990ESAE0018.
Full textDekhli, Faiza. "Étude et réalisation de logiciels d'optimisation contrainte avec analyse des erreurs de calculs et de données." Paris 6, 1985. http://www.theses.fr/1985PA066413.
Full textSafi, Adel. "Ordonnancement de tâches parallèles dans les environnements fortement perturbés." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00846477.
Full textROSSINI, MARCOS R. "Sistema de calculo para gerenciamento de combustivel em reatores tipo PWR atraves da teoria de perturbacao de primeira ordem." reponame:Repositório Institucional do IPEN, 1992. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10311.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Rérat, Michel. "Methode invariante de jauge pour le calcul de proprietes magnetiques : applications a de petites molecules." Paris 6, 1987. http://www.theses.fr/1987PA066024.
Full textStevenson, Paul. "Nuclear structure calculations using many-body perturbation theory with a separable interaction." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312333.
Full textGoldmann, Wolfgang Heinrich. "Pressure and temperature perturbation studies of the interaction between actin and myosin and between calcium and troponin C." Thesis, University of Bristol, 1990. http://hdl.handle.net/1983/ad0a1c91-db58-4c6d-bb6d-3c06b65c6dc3.
Full textMoussaoui, Mohammed. "Approximations lipschitziennes de multifonctions et applications à la relaxation de certains problèmes de contrôle optimal et de calcul de variations." Montpellier 2, 1990. http://www.theses.fr/1990MON20124.
Full textGarniron, Yann. "Développement et implémentation parallèle de méthodes d'interaction de configurations sélectionnées." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30229/document.
Full textThis thesis, whose topic is quantum chemistry algorithms, is made in the context of the change in paradigm that has been going on for the last decade, in which the usual sequential algorithms are progressively replaced by parallel equivalents. Indeed, the increase in processors' frequency is challenged by physical barriers, so increase in computational power is achieved through increasing the number of cores. However, where an increase of frequency mechanically leads to a faster execution of a code, an increase in number of cores may be challenged by algorithmic barriers, which may require adapting of even changing the algorithm. Among methods developed to circumvent this issue, we find in particular Monte-Carlo methods (stochastic methods), which are intrinsically "embarrassingly parallel", meaning they are by design composed of a large number of independent tasks, and thus, particularly well-adapted to massively parallel architectures. In addition, they often are able to yield an approximate result for just a fraction of the cost of the equivalent deterministic, exact computation. During this thesis, massively parallel implementations of some deterministic quantum chemistry algorithms were realized. Those methods are: CIPSI, Davidson diagonalization, computation of second-order perturbation, shifted-Bk, Multi-Reference Coupled-Cluster. For some of these, a stochastic aspect was introduced in order to improve their efficiency. All of them were implemented on a distributed task model, with a central process distributing tasks and collecting results. In other words, slave nodes can be added during the computation from any location reachable through Internet. The efficiency for the implemented algorithms has been studied, and the code could give way to numerous applications, in particular to obtain reference energies for difficult molecular systems
Er-Riani, Mustapha. "Contribution à l'étude des équilibres dynamiques de gouttes et masses fluides." Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_ER_RIANI_M.pdf.
Full textLani, Giovanna. "Vers une nouvelle méthode de calcul pour la fonction de Green à un corps." Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00667923.
Full textGross, Tadeu Junior. "Structure learning of Bayesian networks via data perturbation." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18153/tde-19022019-134517/.
Full textO aprendizado da estrutura de uma Rede Bayesiana (BN) é um problema NP-difícil, e o uso de estratégias sub-ótimas é essencial em domínios que envolvem muitas variáveis. Uma delas consiste em gerar várias estruturas aproximadas e depois reduzir o conjunto a uma estrutura representativa. É possível usar a frequência de ocorrência (no conjunto de estruturas) como critério para aceitar um arco dominante entre dois nós e assim obter essa estrutura única. Nesta pesquisa de doutorado, foi feita uma analogia com um passeio aleatório unidimensional adaptado para deduzir analiticamente um limiar de decisão apropriado para essa frequência de ocorrência. A expressão de forma fechada obtida foi validada usando bases de dados de referência e aplicando o Coeficiente de Correlação de Matthews como métrica de desempenho. Nos experimentos utilizando dados médicos recentes, a BN resultante da frequência de corte analítica capturou as associações esperadas entre os nós e também obteve melhor desempenho de predição do que as BNs aprendidas com limiares vizinhos ao calculado. Na literatura, a característica contabilizada ao longo das estruturas perturbadas tem sido as arestas e não as arestas direcionadas (arcos) como nesta tese. Essa estratégia modificada ainda foi aplicada a um conjunto de dados de idosos para identificar potenciais relações entre variáveis de interesse médico, mas usando um limiar aumentado em vez do previsto pela fórmula proposta - essa cautela deve-se às possíveis implicações sociais do achado. A motivação por trás dessa aplicação é que, apesar da proporção de idosos na população ter aumentado substancialmente nas últimas décadas, os fatores de risco que devem ser controlados com antecedência para garantir um processo natural de declínio mental devido ao envelhecimento permanecem desconhecidos. No modelo estrutural aprendido, investigou-se graficamente o mecanismo de dependência probabilística entre duas variáveis de interesse médico: o fator de risco suspeito conhecido como Síndrome Metabólica e o indicador de declínio mental denominado Comprometimento Cognitivo. Nessa investigação, empregou-se o conceito conhecido no contexto de BNs como D-separação. Esse estudo revelou que a dependência entre Síndrome Metabólica e Variáveis Cognitivas de fato existe e depende tanto do Índice de Massa Corporal quanto da idade.
Castella, Martine. "Photophysique de complexes de molécules aromatiques formés en jet supersonique : spectroscopie electronique et calcul des surfaces d'énergie potentielle." Paris 11, 1987. http://www.theses.fr/1987PA112503.
Full textLucas, Audrey. "Support logiciel robuste aux attaques passives et actives pour l'arithmétique de la cryptographie asymétrique sur des (très) petits coeurs de calcul." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S070.
Full textThis thesis deals with protection development and evaluation against fault attacks (FA) and side channel attacks (SCA) simultaneously. These protections have been developed for elliptic curves cryptography (ECC) and its main operation, the scalar multiplication (MS). Two protections have been proposed. The first is point verification (PV) checking that the current point is effectively on the curve, with a uniformization behavior. Thus, this new SM with PV is robust against some FAs and also SPA, since it is uniform. The second one is called counter iteration (IC). ICC protects the scalar against major FAs with a uniform behavior. Its overhead is very small. Our protections have been implemented on Cortex M0 microcontroller for Weiertrass and Montgomery curves and for different types of coordinates. The overhead is between 48 % and 62 %, in the worst case (when the PV is made at each SM iteration). This overhead is smaller than overhead of usual basic protections against SPA. A theorical activity simulator has also been developed. It reproduces the architecture of a simple 32-bit microcontroller. Theoric activity is modeled by the Hamming weigh variations of manipulated data during execution. Thanks to the simulator, the impact of operands is illustrated for arithmetic units. Moreover, SPA and DPA attacks were made for evaluating our protections. Our protections show some security improvements
Bellet, Benoît. "Utilisation d'une compactification dans le temps pour une suite convergente d'approximations variationnelles-perturbatives de l'oscillateur anharmonique." Montpellier 2, 1994. http://www.theses.fr/1994MON20101.
Full textGOLAZ-CAVAZZI, CATHERINE. "Modelisation hydrologique a l'echelle regionale appliquee au bassin du rhone : comparaison de deux modes de calcul des bilans hydriques de surface et etude de sensibilite a une perturbation des forcages climatiques." Paris, ENMP, 1999. http://www.theses.fr/1999ENMP0918.
Full textDieudonné, Cyril. "Accélération de la simulation Monte Carlo du transport des neutrons dans un milieu évoluant par la méthode des échantillons corrélés." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00934463.
Full textKalache, Djamal. "Contribution à l'étude de la convection naturelle en cavités trapézoïdales chauffées par dessous." Poitiers, 1987. http://www.theses.fr/1987POIT2013.
Full textSyam, Ai͏̈cha. "Contribution aux inclusions différentielles." Montpellier 2, 1993. http://www.theses.fr/1993MON20153.
Full textSoua, Slim. "Formulation couplée BEM/FEM pour un problème de diffraction d'une onde acoustoélastique par une hétérogénéité localisée." Compiègne, 2004. http://www.theses.fr/2004COMP1510.
Full textThe NDT experiments using ultrasonic waves are used to detect and characterise localised heterogeneity. This heterogeneity can be of kind material defect or residual stress. Most of numerical models proposed in the literature do not deal with residual stress. The analytical models are used and are limited enough when dealing with inhomoge¬neous and localised domains. The present work aims to developing a numerical method of resolution applied to the study of elastic wave diffraction by localised heterogeneity. For that purpose, theoretical study of linearized motion equations in prestressed structure is developed, then a variational formulation is used for the numerical resolu¬tion. The numerical method, we propose, is based on boundary element (BEM) and finite element (FEM) methods. Each of these methods is more suited to deal with some of the limitations, so we use both methods in coupled formulation. Results are obtained and compared to several analytical and semi-analytical models, the cases of plane wave diffraction and modal waves are treated: Lamb or Stoneley modal wave. The agreement for a/5 meshes proves the efficiency of the numerical model
Evangelisti, Stefano. "Developpement de methodes d'interaction de configurations et d'hamiltoniens effectifs dans le cadre du probleme a n-corps." Toulouse 3, 1988. http://www.theses.fr/1988TOU30034.
Full textChesneaux, Jean-Marie. "Etude theorique et implementation en ada de la methode cestac." Paris 6, 1988. http://www.theses.fr/1988PA066143.
Full textYehya, Yassar. "Propagation des ondes acoustiques dans les conduites cylindriques de révolution." Poitiers, 1988. http://www.theses.fr/1988POIT2275.
Full textTimrov, Iurii. "Étude ab initio des plasmons et du couplage électron-phonon dans le bismuth: de la modélisation de l'absorption des porteurs libres à une nouvelle méthode pour le calcul de spectre de perte d'énergie électronique." Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00823758.
Full textZhang, Zuman. "Open heavy-flavour measurements via muons in proton-proton and nucleus-nucleus collisions with the ALICE detector at the CERN-LHC." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC077/document.
Full textThe study of ultra-relativistic heavy-ion collisions aims at investigating a state of strongly-interacting matter at high energy density and temperature, the Quark-Gluon Plasma (QGP). Heavy quarks (charm and beauty) are predominantly produced in initial hard scattering processes during the early stage of the collisions and experience the full evolution of the medium. Therefore, the measurement of open heavy flavours should provide essential information on the QGP properties. Similar measurements in small systems are also essential for a comprehensible understanding of the QGP properties. The study of open heavy flavours in proton-proton (pp) collisions provides the mandatory reference for measurements in heavy-ion collisions. This thesis presents measurements of the production of muons from heavy-flavour hadron decays at forward rapidity (2.5 < y < 4) in pp collisions at sqrt (s) = 5.02 TeV, Pb-Pb collisions at sqrt (sNN) = 2.76 and 5.02 TeV and Xe-Xe collisions at sqrt (sNN) = 5.44 TeV collected with the ALICE detector at the CERN-LHC. The differential production cross sections of muons from heavy-flavour hadron decays in pp collisions at sqrt (s) = 5.02 TeV are obtained in a wide transverse momentum interval, 2 < pT < 20 GeV/c, and with an improved precision compared to the previously published measurements at sqrt (s) = 2.76 and 7 TeV. The measurements are described within uncertainties by predictions based on perturbative QCD. A strong suppression of the yield of muons from heavy-flavour decays is observed in the 10% most central Pb-Pb collisions at both sqrt (sNN) = 2.76 and 5.02 TeV. This suppression is due to final-state effects induced by the hot and dense medium. The suppression in Xe-Xe collisions is similar to that observed with Pb-Pb collisions. The comparison in the two colliding systems provides insight in the path-length dependence of medium-induced parton energy loss. The results constrain model calculations
Di, Loreto Michaël. "Méthodologie pour l'analyse et la commande des systèmes à retards." Phd thesis, Ecole centrale de nantes - ECN, 2006. http://tel.archives-ouvertes.fr/tel-00149948.
Full textClimaco, de Melo Lara. "La Propagation des erreurs dans les modèles de croissance forestière dans un contexte de prévision à l'échelle régional." Thesis, Paris, AgroParisTech, 2018. http://www.theses.fr/2018AGPT0006.
Full textIn forestry, tree-level growth models provide predictions of forest dynamics andthereby, they support decision-making. Although they are widely used, the uncertainty of their predictions is rarely assessed. Understanding the sources of uncertainty and estimating their impact is an essential step forward in a period where large-scale forecasts are becoming more popular. This thesis addresses the issue of uncertainty estimation in regional growth forecasts. The effects of large-scale disturbances were also studied.The growth model ARTEMIS-2009, which applies to most forest types in Quebec,Canada, was taken as a case study. A bootstrap hybrid estimator was used toestimate the model- and the sampling-related variances. The total variance wasthen decomposed to determine which model component induced the greatest shareof variance in the forecasts. Then, the survival analysis approach was used to develop a harvest model based on plot and regional variables. This model was integrated into ARTEMIS so that harvesting combined with spruce budworm (SBW) outbreaks were accounted in the simulations. Then, their contributions in terms of uncertainty were estimated. The results revealed that the sampling accounted for most of the variance in short-term forecasts. In long-term forecasts, the model contribution turned out to be as important as that of the sampling. The variance decomposition per model component indicated that the mortality sub-model induced the highest variability in the forecasts. A great deal of uncertainty was induced by the natural disturbances when they were accounted for in the projections. In particular, SBW showed to be the most important source of uncertainty compared to harvest activities and sampling. In the light of these results, our recommendations are that the effort to reduce uncertainty should focus on the sampling in short-term forecasts, and on the mortality sub-model and SBW occurrence in mid- and long-term forecasts
Cancès, Eric. "Simulation moléculaire et effets d'environnement - Une perspective mathématique et numérique." Phd thesis, Ecole des Ponts ParisTech, 1998. http://pastel.archives-ouvertes.fr/pastel-00000101.
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