Dissertations / Theses on the topic 'Méthode des clusters couplées'
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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
Briceno-Arias, Luis. "Problèmes d'inclusions couplées : éclatement, algorithmes et applications." Paris 6, 2011. http://www.theses.fr/2011PA066622.
Tournour, Michel. "Modélisation numérique par éléments finis et éléments finis de frontière du comportement vibroacoustique de structures complexes assemblées et couplées à une cavité." Compiègne, 1999. http://www.theses.fr/1999COMP1197.
Courtois, Théophane. "Qualité spectrale des prédictions acoustiques obtenues par méthode géométrique dans des cavités couplées et absorbantes : moyennes fréquences." Rouen, 2002. http://www.theses.fr/2002ROUES047.
Numerical modeling of coupling in acoustics in the medium frequency range poses problems due to the size of the domains. With the ray method in damped cavities, it is possible to target a small number of points inside the domain and, subsequently, to reduce calculation time, making it possible to look for spectral instead of harmonic results. Does this still hold when the cavities are coupled thanks to an integral representation using such Green functions? An original image-source technique is first developed to avoid geometrical approximations. But in fact, due to inherent approximations, the ray method is inaccurate in the presence of absorbent walls. An analysis shows that a hierarchy exists among the errors arising from the rays, and finally it appears that only the grazing rays must be replaced by another approximation. In these conditions, the ray method is capable of solving coupling problems in medium frequency range as confirmed by finite elements and experimental comparisons
Morandini, Jacques. "Contribution à la résolution multi-méthode des équations aux dérivées partielles couplées rencontrées en magnéto-thermo-hydrodynamique." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0068.
Tannous, Mickhael. "Développement et évaluation d'approches de modélisation numérique couplées 1D et 3 D du contact rotor-stator." Ecole centrale de Nantes, 2013. http://www.theses.fr/2013ECDN0015.
Rotor dynamic problems with rotor to stator contact interactions are dealt with in the literature by 1D local models. This leads to an affordable simulation time, but the corresponding approximations are difficult to assess. Since the contact is limited in space and time, the same strategy can therefore be used with 3D models. A strategy, called switch, allowing the use of a beam model and a 3D model (or beam-3D mixed model), at two different stages of the same simulation, is developed. It is implemented in a non-intrusive way for the simulation of transient dynamic problems, with or without an overall rotation, solved by an implicit time integration scheme. The switch is validated by comparison with a 3D reference solution obtained by performing the full simulation on the 3D model. We, then, compare and analyze the results of 1D and 3D rotor-stator contact problems, for different contact conditions more and less severe. The rotor vibrations are due to rotating imbalance at a given constant rotating speed. It appears that the differences between the 1D and the 3D results are not obvious on the rotor orbits. However, the limitations of the 1D simulation are highlighted. Indeed, the rigid body section assumption in a beam model of the rotor leads to approximations in the spatial distribution of the contact forces and their intensity. The 3D model, however, can present some local effects in the vicinity of the contact zone
Halbert, Loïc. "La méthode Equation of Motion Coupled Cluster pour la modélisation des états excités et propriétés des molécules contenant des éléments lourds." Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR038.
In this thesis, we seek to obtain certain molecular properties for species containing heavy elements or presenting atmospheric interests. For this, we use techniques to characterize the core electrons, with ionization potentials (IP) or with excitation energies (EE), allowing for example to respectively interpret X-ray Photoelectron Spectroscopy(XPS) and X-ray Absorption Spectroscopy (XAS). We also seek to characterize valence electrons through the polarizability, which is used for example to develop force fields. When we work with heavy elements or with core electrons, we must take relativistic effects into account. We therefore used the Dirac-Coulomb(-Gaunt) Hamiltonian. Furthermore, to compare our results with experiments, we need precise methods. Thus, we will work with the Coupled-Cluster (CC) method, and will use the Equation of Motion Coupled-Cluster (EOM-CC) method to obtain the IPs, EEs and electron affinities (EA). However, these two elements (4-component Hamiltonians and post-Hartree-Fock methods) imply considerable computational costs, requiring the resources of High Performance Computing (HPC) platforms.This thesis presents a study of the Core-Valence Separation (CVS) method, which will allow us to reach the properties of core electrons (IP and EE) with EOM-CC. We provide a detailed investigation of the performance of different Hamiltonians, in particular the exact two-component molecular mean field Hamiltonian. Second, we will focus on the perturbative approximations (Partioned and Many Body Perturbation Theory 2d order (MBPT (2)) to be applied to the EOM-CC matrix to limit computational costs, including for core processes. Finally, we present the work carried out in Exacorr, a new relativistic coupled cluster implementation for hybrid and massively parallel architectures. We will finish by outlining the formalism and working equations for the Linear Response Coupled-Cluster (LRCC) method, through which analytical (frequency-dependent) molecular polarizabilities can be obtained
Djehaf, Fatiha. "Etude du problème de Maxwell quasi-stationnaire par équations intégrales en champ couplées à une méthode par éléments finis." Paris 11, 2008. http://www.theses.fr/2008PA112012.
This thesis concerns the modeling of eddy currents appearing in a not simply connected conductor (NSC) put in a not bounded domain. We associate a finite element method in the conductor and an integral method on its boundary. Usually, the integral method used for this problem implies to discretize a Poincaré-Stecklov’s operator; this is very heavy and does not easily permits to consider NSC. We therefore choose to use fields integral representations similar to Stratton-Chu’s formulas but adapted to the quasi-stationary approximation. We couple a variational formulation of these integral formulations to a finite element formulation in the conducting volume. We show that, in the used functional frame, (H(curl) in the volume and tangential traces spaces on the boundary), the continuous problem is well defined. We next present the discrete problem study with Nédélec’s finite elements of order 1. We show that it is well posed and we study an a priori estimation error. We next proceed to the code validation, first on a simple problem , the analytical solution of which is known (conducting sphere in an homogeneous magnetic field) and then on an international test problem, where the conductor is not simply connected and for which we have results obtained with other logicials. We so verify that our code does not need any adaptation for the not simply connected cases and that our results are quite satisfying
Agroum, Rahma. "Discrétisation spectrale des équations de Navier-Stokes couplées avec l'équation de la chaleur." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066195/document.
In this thesis we consider the discretization by spectral method and the numerical simulation of a viscous incompressible fluid in the domain ?, the model being the Navier-Stokes equations. We have chosen to couple them with the heat equation where the viscosity of the fluid depends on the temperature, with boundary conditions which involve the velocity and the temperature. The method is proved to be optimal in the sense that the order of convergence is only limited by the regularity of the solution. The numerical analysis of the discrete problem is performed and numerical experiments are presented, they turn out to be in good coherence with the theoretical results. Finally, we consider the unsteady Navier-Stokes/heat equations which models the time-dependent flow. We propose a discretization of this problem that relies on a backward Euler's scheme in time and spectral methods in space and present some numerical experiments which confirm the interest of the discretization
Fakhreddine, Khaled. "Contribution à la théorie de collision : résolution d'un système d'équations radiales couplées de Schrodinger par la méthode des fonctions canoniques." Lyon 1, 1993. http://www.theses.fr/1993LYO10008.
El, Kamoun Najib. "Simulation par la méthode de convolution des lignes de transmission couplées, dissipatives et dispersives : application aux interconnexions de circuits logiques rapides." Grenoble INPG, 1990. http://www.theses.fr/1990INPG0114.
Tahri, Youssef. "Contribution à l'étude théorique par la méthode MS-X α, de composés susceptibles de se former sur InP." Lyon 1, 1989. http://www.theses.fr/1989LYO10059.
Guilleron, Jean-Philippe. "Contrôlabilité d'une équation de Korteweg-de Vries et d'un système d'équations paraboliques couplées. Stabilisation en temps fini par des feedbacks instationnaires." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066277/document.
This doctoral thesis focuses on three fields of Control Theory: the control on the edge of the Korteweg-de Vries equation, the control of three heat equations coupled by cubic terms, and the stabilisation in finite time of three classic systems of finite dimension. For the KdV equation, we first demonstrate a Carleman inequality using a well-chosen exponential weight, then we deduce the controllability at zero of the equation. For the system of three heat equations coupled by cubic terms, we show the global controllability at zero even though the linearized system around zero is not controllable. We apply the return method to obtain local controllability: we build control system trajectories going from zero to zero and whose linearised systems are controllable. Then a scale change allows us to obtain a global result. Finally, concerning the three systems of finite dimension, these systems are controllable systems but the linearised systems are not controllable and are not stabilised with means of continuous stationary feedback. We construct an explicit time-dependent feedback leading to a stabilisation in finite time. For this we deal with different parts of systems during different intervals of time
Faucher, Vincent. "Méthodes numériques et algorithmes parallèles pour la dynamique rapide des systèmes fluide-structure fortement couplés." Habilitation à diriger des recherches, INSA de Lyon, 2014. http://tel.archives-ouvertes.fr/tel-01011205.
Belghoul, Khaled. "Les réseaux et clusters d'innovation, dynamique d'évolution et de restructuration de l'innovation dans l'industrie biopharmaceutique : éléments de conceptualisation et analyse des cas de l'Ile-de-France et de la région lyonnaise." Thesis, Amiens, 2018. http://www.theses.fr/2018AMIE0058.
The structuring of innovation in science-based industries in the form of networks has become the new organizational dynamics of innovation over the past decades. More specifically, in the biopharmaceutical industry, this new organizational dynamic refers to the logic of efficiency and rationalization efforts in R&D. The nature of innovation and technological interdependencies between different actors are all elements that drive the organization in innovation networks. In this perspective, the study of the process of emergence, structuration and evolution of clusters of innovation in the biopharmaceutical industry enables us to understand the benefits of spatial proximity (knowledge spillovers, shared infrastructure...) and other benefits of organizational and strategic proximity. This thesis also attempts to answer the question of essential factors in the emergence and development of these innovation clusters and that through several case studies of the emergence of clusters of innovation in the biopharmaceutical industry in the United States and Europe.In our empirical study, we chose to analyze this structure in terms of innovation clusters for two regions in France, Ile-de-France and the Lyon region. Through the approach of collaborative projects, we are come to rebuild the two networks and identify the role of some major players in defining the morphology of the network and the transmission and dissemination of knowledge within it. The results also show a structure in networks at multiple scales. The work done contributes to the understanding of the dynamics of interaction within networks of R&D in science-based sectors
Bah, Thierno Moussa. "Développement et caractérisation d’un démonstrateur de générateur thermoélectrique à base de membranes de silicium couplées à de l’ingénierie phononique." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I036/document.
The lack of reliable, safe and low-cost energy source seems to delay the blooming of the internet of things (IoT) and wireless sensors nodes. Thermoelectric harvesters feature those key advantages. Silicon presents the advantages to be most abundant, less environmental harmful and to benefit from facilities and technological processes for low cost thermoelectric harvesters mass production compared to the conventional materials (bismuth telluride alloys). However, silicon is a poor thermoelectric material due to its high thermal conductivity ( ). The possibility to reduce the thermal conductivity while preserving electrical conductivity and Seebeck coefficient is the key to upgrade silicon as an efficient thermoelectric material. To that end, efforts are oriented towards the phononic part of heat transport, which is the dominant contribution in semiconductors. The researches carried out during this thesis dealt with the integration of phonon engineered silicon membranes into thermoelectric harvester demonstrators and their characterizations with respect to the state of the art. The results demonstrated the feasibility of a silicon based thermoelectric harvester exhibiting performance (from few µW/cm2 for ΔT~5-10K to few mW/cm2 for ΔT>100K) sufficient for autonomous sensor nodes’ power supplying and comparable performance with the bismuth telluride state of the art harvester according to the harvesters’ cooling conditions. Moreover, this thesis demonstrated, in addition to the energy harvesting, the possibility of developing silicon based thermoelectric coolers, opening the way to possible integration of thermoelectric coolers in silicon based micro-electronic devices
Roques, Jérôme. "Modélisation de l'adsorption dissociative de molécules diatomiques sur des agrégats métalliques par la méthode de la fonctionnelle de la densité : comparaison avec les propriétés du massif et de la surface infinie." Toulouse, INPT, 2001. http://www.theses.fr/2001INPT010G.
Ponchel, Freddy. "ELFI : calculateur électromagnétique pour l'établissement de schémas électriques équivalents aux interconnexions "cuivre" couplées et pour la caractérisation des matériaux." Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-221.pdf.
Mouhat, Félix. "Fully quantum dynamics of protonated water clusters." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS056.
There is no theory up to now able to provide an accurate and quantitative description of the proton transfer (PT) yet. Indeed, the complexity of the problem stems from the large diversity of the existing interactions in liquid water, namely: non bonding Van der Waals interactions, weakly covalent bonds and remarkably strong H-bonds. The latter ones are at the origin of the numerous fascinating properties of water at the macroscopic scale. In addition to such interactions, the nuclear quantum effects arising from the hydrogen light mass deeply modify the potential energy surface, and must be taken into account. In this thesis, we propose a fully quantum approach based on an almost exact description of the electronic wave function by means of Quantum Monte Carlo (QMC) methods. Our novel technique combines QMC with a Langevin-based Molecular Dynamics and the Feynman's path integral formalism. This allows one to perform fully quantum simulations of systems in gas or condensed phase, at an unprecedented level of accuracy,. We apply our approach to neutral or charged protonated water clusters to shed light on the microscopic phenomena driving the proton diffusion in such systems. We discovered that the proton hopping is optimal for temperatures close to ambient conditions, due to the subtle competition between thermal and nuclear quantum effects. This is highly suggestive of the importance of quantum nuclear effects to make PT processes - relevant for life - most efficient at room temperature
Boynard, Anne. "Exploitation des observations satellitaires IASI couplées à un modèle régional pour l'amélioration de la prévision des épisodes de pollution en ozone." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00489656.
Gomez, Garcia José Gregorio. "Théorèmes limites pour des fonctionnelles de clusters d'extrêmes et applications." Thesis, Cergy-Pontoise, 2017. http://www.theses.fr/2017CERG0916/document.
This thesis deals mainly with limit theorems for empirical processes of extreme cluster functionals of weakly dependent random fields and sequences. Limit theorems for empirical processes of extreme cluster functionals of stationnary time series are given by Drees & Rootzén [2010] under absolute regularity (or "ß-mixing") conditions. However, these dependence conditions of mixing type are very restrictive: on the one hand, they are best suited for models in finance and history, and on the other hand, they are difficult to verify. Generally, for other models common in applications, the mixing conditions are not satisfied. In contrast, weak dependence conditions, as defined by Doukhan & Louhichi [1999] and Dedecker & Prieur [2004a], are dependence conditions which generalises the notions of mixing and association. These are easier to verify and applicable to a wide list of models. More precisely, under weak conditions, all the causal or non-causal processes are weakly dependent: Gaussian, associated, linear, ARCH(∞), bilinear and Volterra processes are some included in this list. Under these conveniences, we expand some of the limit theorems of Drees & Rootzén [2010] to weakly dependent processes. These latter results are used in order to show the convergence in distribution of the extremogram estimator of Davis & Mikosch [2009] and the functional estimator of the extremal index introduced by Drees [2011] under weak dependence. We prove an extreme value theorem for weakly dependent stationary random fields and we propose, under the same conditions, a domain of attraction criteria of a law of extremes. The document ends with limit theorems for the empirical process of extreme cluster functionals of stationary weakly dependent random fields, deriving also the convergence in distribution of the estimator of an extremogram for stationary weakly dependent space-time processes
Ben, Khodja Arbia. "Méthodologies numériques et expérimentales pour la compréhension et la prédiction du phénomène d'hydroplanage des pneumatiques par simulations numériques couplées SPH-Eléments Finis et mesures PIV." Electronic Thesis or Diss., Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0050.
The wet grip performance of tires is an essential criterion affecting the safety of passengers. In this situation, the tire/ground contact becomes more complex to understand and model, involving non-trivial physical mechanisms such as fluid-structure coupling and turbulent flows. In the vision of improving our understanding of tires’ hydroplaning, this thesis aims to set up a comparison strategy between the SPH-Finite Elements coupled numerical simulations and the r-PIV testresults. Indeed, the SPH method has many advantages due to its Lagrangian and meshless nature to model the fluid part. Moreover, its coupling with the finite element method is relatively easy. In addition, the r-PIV was recently introduced for experimental investigations of a tire rolling over a water puddle. This new approach performed effectively as a powerfultool for validating numerical simulations based on local comparisons of the water circulation for a given tire tread. Finally, numerical simulations also evaluate r-PIV thanks to a 3D vision of the phenomenon and access to data that are still inaccessible experimentally
Fabregas, Flavia Francesc. "A numerical tool for the frequency domain simulation of large clusters of wave energy converters." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0011.
Compact arrays of small wave absorbers constitute an example of the multiple existing categories of wave energy converters (WECs) and have been identified as being an advantageous solution for the extraction of wave energy when compared to a big isolated point absorber. Among the numerous challenges associated with the numerical modeling of such devices, one of the most relevant one is the evaluation of the hydrodynamic interactions amid the large number of floats O(100) they are composed of. Direct computations with standard Boundary Element Method (BEM) solvers, used extensively in wave/structure interaction problems, become prohibitive when the number of bodies increases. Thus, there is a need to employ an alternative approach more suitable for the study of the multiple-scattering in large arrays. In this work, the Direct Matrix Method interaction theory has been implemented. Based on characterizing the way a WEC scatters and radiates waves, this methodology enables one to significantly reduce the number of unknowns of the classical boundary value problem dealt with by standard BEM solvers and, therefore, the computational time. The acceleration provided by the numerical tool developed has allowed examining the power capture of a generic bottom-reference heave-buoy array WEC and optimizing its layout. We have shown that there exist an optimum number of floats for a given device footprint. Exceeding this number results in a “saturation” of the power increase which is undesirable for the economic viability of the device
Mouhat, Félix. "Fully quantum dynamics of protonated water clusters." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS056/document.
There is no theory up to now able to provide an accurate and quantitative description of the proton transfer (PT) yet. Indeed, the complexity of the problem stems from the large diversity of the existing interactions in liquid water, namely: non bonding Van der Waals interactions, weakly covalent bonds and remarkably strong H-bonds. The latter ones are at the origin of the numerous fascinating properties of water at the macroscopic scale. In addition to such interactions, the nuclear quantum effects arising from the hydrogen light mass deeply modify the potential energy surface, and must be taken into account. In this thesis, we propose a fully quantum approach based on an almost exact description of the electronic wave function by means of Quantum Monte Carlo (QMC) methods. Our novel technique combines QMC with a Langevin-based Molecular Dynamics and the Feynman's path integral formalism. This allows one to perform fully quantum simulations of systems in gas or condensed phase, at an unprecedented level of accuracy,. We apply our approach to neutral or charged protonated water clusters to shed light on the microscopic phenomena driving the proton diffusion in such systems. We discovered that the proton hopping is optimal for temperatures close to ambient conditions, due to the subtle competition between thermal and nuclear quantum effects. This is highly suggestive of the importance of quantum nuclear effects to make PT processes - relevant for life - most efficient at room temperature
Szarf, Krzysztof. "A numerical study of the influence of grain shape on the mechanical behaviour of granular materials : application : load transfer above underground conduits." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENI095/document.
This study was devoted to the in_uence of grain shape on the mechanical behaviourof granular materials and its e_ect on load transfer over underground pipes. Shapeof convex polygons and concave clumps of discs was generalised with a geometricalparameter α. In the study a Discrete Element Modeling (DEM) approach was used.Biaxial compression of granular assemblies revealed that mechanical and geometricalproperties like porosity, macroscopic friction or shear localisation depends both on αand on grain (non-)convexity.The intergranular load transfer over a _exible pipe was studied both experimentally(2D rods in a plain strain apparatus) and numerically (DEM). The experimentsshowed that the pipe has no signi_cant impact on the macroscopic behaviour of theassembly. The numerical model complied with the experiments and revealed that thearching e_ect in a sheared granular medium exists above the pipe and is magni_edwith the increase of α of the grains
Delattre, Frédéric. "Approche locale des matériaux par la méthode ab initio des clusters environnés : du solide périodique (ZnS) au cristal laser dopé (le niobate de lithium dopé par l'ion Nd3+." Lille 1, 2000. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2000/50376-2000-174.pdf.
Aldair, Misael Wilken. "Shedding X-rays on molecules through the lenses of relativistic electronic structure theory." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR043.
This thesis aims to investigate the electronic structure of actinides by means of ab initio relativistic quantum chemistry methods, with a specific emphasis on the spectroscopic observables of the uranyl moiety (UO22+). Considering the pivotal role of this unit in the solid-state and solution chemistry of uranium, one of the most abundant and stable actinides on earth, as well as recent advancements in synchrotron radiation facilities, our investigation relies on evaluating the interaction of x-ray photons with the uranyl unit in varying degrees of complexity, ranging from molecules to crystalline solids.First, we showcase how the resonant-convergent formulation of response theory can be employed to investigate the X-ray absorption fine structure (XAFS) of actinides. 4-component damped-response time-dependent density functional theory (4c-DR-TD-DFT) simulations for the uranyl tetrachloride dianion ([UO2Cl4]2-) were found to be consistent with previous data for angle-resolved near edge x-ray absorption spectroscopy (NEXAFS) at the oxygen K-edge and high energy resolution fluorescence detected (HERFD) at the uranium M4- and L3-edges of the dicesium uranyl tetrachloride crystal (Cs2UO2Cl4), a prototype system for actinide electronic structure investigations.We then present the results of collaborative work with the Rossendorf Beamline at the European Synchrotron Radiation Facility (ESRF). 2-component TD-DFT simulations within the Tamm-Dancoff approximation (2c-TDA) and HERFD measurements uranyl systems within different structural motifs highlight the role of charge transfer states in determining the spectral features at the uranium M4-edge.The role of orbital correlation and relaxation in the core-ionization energies of heavy elements was investigated using the recently developed core-valence-separation equation-of-motion coupled-cluster method (CVS-EOM-CC). We also evaluated the performance of various 4- and 2-component Hamiltonians for calculating these properties. The results of this investigation highlight the importance of computing two-electron interaction beyond the zeroth order truncation, i.e., the Coulomb term, when working at the tender (1 keV - 5 keV) and hard x-ray (5 keV - 200 keV) ranges.We also evaluated the performance of quantum-chemical embedding methods to account for environmental effects. Specifically, we employed the frozen density embedding (FDE) method, which allowed us to gain valuable insights into how the equatorial ligands of the uranyl ion influence its spectroscopic properties. Notably, this method successfully addressed the role of such interactions in binding energies in the soft X-ray range and in the peak splittings observed in the emission spectra at the U M4-edge. The latter is particularly significant as it has been instrumental in addressing a long-standing problem in actinide science: the role of 5f orbitals in actinyl bonding.In summary, this thesis presents fundamental research work that aims to push the boundaries of ab initio quantum chemical methods when addressing spectroscopic observables toward the bottom of the periodic table, and the findings of this work capture how these approaches can provide further insights into state-of-the-art experiments
Garreau, Alexandre. "Design de nanofils luminescents organiques et hybrides à base de clusters de composés de métaux de transition." Phd thesis, Université du Maine, 2013. http://tel.archives-ouvertes.fr/tel-00950272.
Leyrat, Clémence. "Biais de sélection dans les essais en clusters : intérêt d'une approche de type score de propension pour le diagnostic et l'analyse statistique." Paris 7, 2014. http://www.theses.fr/2014PA077064.
This work aimed to study propensity score (PS)-based approaches for analysis of results of cluster randomized trials (CRTs) with selection bias. First, we used Monte Carlo simulations to compare the performance of 4 PS-based methods (direct adjustment, inverse weighting, stratification and matching) and classical multivariable regression when analyzing results of a CRT with selection bias. For continuous outcomes, both multivariable regression and PS-based methods (except matching) removed the bias. Conversely, only direct adjustment on PS provided an unbiased estimate of treatment effect for a low-incidence binary outcome. Second, we developed a tool for detecting selection bias that relies on the area under the receiver operating characteristic curve of the PS model. This tool provides, for a fixed number of covariates and sample size, a threshold value beyond which one could consider the existence of selection bias. This work also highlights the complexity of implementing PS-based methods in the context of CRTs because of the hierarchical structure of the data, as well as the challenges linked to the choice of the statistical method in a causal inference framework
Paradis, Delphine. "Méthode d'analyse dans le miel de trois familles d'insecticides (nicotinoïdes, pyréthrinoïdes et pyrazoles) par chromatographies en phase gazeuse et en phase liquide couplées à la spectrométrie de masse en tandem. : application à l' étude de contamination de ruches." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4058.
Several extraction and analytical techniques existing to study insecticides in honey do not always allow reaching low limits of detection. However, to evaluate the toxicity of pesticides, values of limits of detection have to be close to 1 ng/g. The aim of this work was to develop extraction and analytical methods compatible with various types of honey (nectars and honeydews, monofloral and multifloral) and allowing to look for 25 insecticides belonging to 3 families (nicotinoids, pyrethroids and pyrazoles), with the lowest possible limits of detection and eliminating the maximum interference due to the matrix. After comparison of different extraction methods, the reserved technique is based on the QuEChERS EN 15662 method, which consists of an extraction and a purification with mixtures of salts adapted to the matrix and to the compounds to be extracted. Analysis were then performed using gas chromatography coupled with tandem mass spectrometry (GC-MS²) for the pyrazoles and the pyrethroids, and using high performance liquid chromatography coupled with tandem mass spectrometry (LC-MS²) for the nicotinoids and one pyrazole. Device settings have to be optimized to obtain a very low limit of detection. The mean extraction yields were typically between 60 and 140%. The methods are specific for tested honeys. These methods are applicable to analyze commercial honeys and allow reaching limits of detection between 0.2 and 0.7 ng/g. In practice, the dosage of these 3 families in different types of honeys, at low concentrations can be made in routine in an analysis laboratory
Toufayli, Laila. "Stabilisation polynomiale et contrôlabilité exacte des équations des ondes par des contrôles indirects et dynamiques." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00780215.
Teyssier, Cécile. "Spectrométrie de masse COINTOF : Conception et d'un analyseur à temps de vol et développement de la méthode d'analyse." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00744850.
Ngandjong, Alain Cabrel. "Modélisation structurale des clusters d’alliages supportés : effet du support de silice et effet de taille." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2070/document.
Numerical simulations have so far neglected the influence of amorphous silica substrate on the structure of metallic nanoparticles due to its relatively weak interaction with deposited nanoparticles. However, experimental studies have often shown a truncation effect on the structure of nanoparticles. The idea of this work was to study the influence of this substrate on the structure of silver nanoparticles using molecular modeling (Monte Carlo and molecular dynamics). The objective of this work was firstly to determine silver-silica interatomic potential. This was achieved using experimental data of wetting angles in solid and liquid phase. On the other hand, silver-silica interaction intensity was determined by DFT calculations on cristobalite which is a polymorph of crystalline silica having the same density as amorphous silica. The adhesions energies obtained were used to fit the Lennard-Jones parameters for the silver-silica interaction. The study of the structural stability of silver nanoparticles supported at zero temperature was performed for three levels of approximation of the support. (1): the smooth wall approximation where the support is described by a square-well whose depth is related to the adhesion energy of the nanoparticle, (2): an atomistic model of flat amorphous silica, (3): an atomistic model of rough amorphous silica. The influence of the temperature on the structure was investigated by melting and recrystallization of the silver nanoparticles deposited on the two silica supports. In order to study the temperature stability of the nanoparticles the free energy calculation of the nanoparticles was discussed
Farizon, Michel. "Agrégats d'hydrogène - Structure et interaction avec des cibles solides." Phd thesis, Université Claude Bernard - Lyon I, 1988. http://tel.archives-ouvertes.fr/tel-00795192.
Castanié, Laurent. "Visualisation de données volumiques massives : application aux données sismiques." Thesis, Vandoeuvre-les-Nancy, INPL, 2006. http://www.theses.fr/2006INPL083N/document.
Seismic reflection data are a valuable source of information for the three-dimensional modeling of subsurface structures in the exploration-production of hydrocarbons. This work focuses on the implementation of visualization techniques for their interpretation. We face both qualitative and quantitative challenges. It is indeed necessary to consider (1) the particular nature of seismic data and the interpretation process (2) the size of data. Our work focuses on these two distinct aspects : 1) From the qualitative point of view, we first highlight the main characteristics of seismic data. Based on this analysis, we implement a volume visualization technique adapted to the specificity of the data. We then focus on the multimodal aspect of interpretation which consists in combining several sources of information (seismic and structural). Depending on the nature of these sources (strictly volumes or both volumes and surfaces), we propose two different visualization systems. 2) From the quantitative point of view, we first define the main hardware constraints involved in seismic interpretation. Focused on these constraints, we implement a generic memory management system. Initially able to couple visualization and data processing on massive data volumes, it is then improved and specialised to build a dynamic system for distributed memory management on PC clusters. This later version, dedicated to visualization, allows to manipulate regional scale seismic data (100-200 GB) in real-time. The main aspects of this work are both studied in the scientific context of visualization and in the application context of geosciences and seismic interpretation
Berthon, Julie. "Nouvelle approche de la fiabilité opérationnelle." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13657/document.
The thesis went within the scope of an agreement between the University Bordeaux I and the Thales Avionics company. It constitutes an original analysis of the reliability of complex materials equipments, with the prospect of control and improvement. The thesis consists of two separate parts connected to the problems met by the manufacturer: - The first part deals with the analysis of "clusters" of undesirable events (chain of disasters, series of failures,...). It appeals to the scan statistics in order to estimate the probability of occurrence of a cluster of events. A Monte Carlo simulation implemented in a dedicated algorithm, then a Monte Carlo simulation supported by a Petri net model, are proposed. Several markovian approaches are then developed. - The second part deals with the analysis of feedback in a non common context when the only information available is the number of equipments which are delivered during each period and the number of those which are removed during each period. An innovative approach, allowing to obtain the intrinsic failure rate of the materials under study according to the production flow and the removal flow, is explained
Aoun, Joe. "Validation de la simulation Monte-Carlo de la gamma-caméra petit animal Biospace sur la grille de calcul légère CiGri. Application à l'évaluation de l'algorithme de l'inversion analytique de la transformée de Radon atténuée." Phd thesis, Clermont-Ferrand 2, 2009. http://www.theses.fr/2009CLF21973.
Ohm, Thorsten. "Effet tunnel quantique de l'aimantation dans un aimant moleculaire, Fe8." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10187.
Aoun, Joe. "Validation de la simulation Monte-Carlo de la gamma-caméra petit animal Biospace sur la grille de calcul légère CiGri. Application à l'évaluation de l'algorithme de l'inversion analytique de la transformée de Radon atténuée." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2009. http://tel.archives-ouvertes.fr/tel-00724964.
Kéou, Noutcheuwa Rodrigue Giselin. "Une nouvelle méthode smoothed particle hydrodynamics : simulation des interfaces immergées et de la dynamique Brownienne des molécules avec des interactions hydrodynamiques." Thèse, 2012. http://hdl.handle.net/1866/9705.
In this thesis we develop a new smoothed particle hydrodynamics (SPH) method suitable for solving the incompressible Navier-Stokes equations, even with singular forces. Singular source terms are handled in a manner similar to that in the immersed boundary (IB) method of Peskin (2002) or in the method of regularized Stokeslets (Cortez, 2001). The numerical scheme implements a second-order pressure-free projection method due to Kim and Moin (1985) and completely obviates the difficulties that may be faced in prescribing Neumann pressure boundary conditions. We present two variants of this approach, one Langrangian which is commonly used and one Eulerian, simply because we consider that the SPH particles are quadrature points on which the fluid properties are calculated, therefore, these points can be kept fixed in time. The proposed SPH method is first tested on the planar start-up Poiseuille problem and a detailed error analysis is performed. For this problem, the results are similar whether the SPH particles are free to move or fixed on a regular grid. Our hybrid SPH-IB method is then used to calculate the dynamics of a stretched immersed elastic membrane. The membrane is represented by a cubic spline along which the tension in the membrane is computed and transmitted to the surrounding fluid. The Navier-Stokes equations with singular force due to the membrane are then solved to determine the velocity of the fluid in which the membrane is immersed. The fluid velocity thus obtained is interpolated on the interface, to determine its displacement. We discuss the advantages, in this problem, of fixing the SPH particles, rather than allowing them to move with the fluid. A new coupled Brownian dynamics-SPH method for the computation of confined flows of non-dilute polymer solutions with full hydrodynamic interaction and excluded volume forces is next presented. The starting point for the algorithm is the system of coupled Langevin equations for polymer and solvent (CLEPS) (see Oono and Freed (1981) and Öttinger and Rabin (1989), for example) describing, in the present case, the microscopic dynamics of a flowing polymer solution with a bead-spring representation of the macromolecules. Numerical tests of some two-dimensional channel flows reveal that use of a second-order projection scheme coupled with fixed SPH quadrature points leads to second-order velocity convergence and almost second-order pressure convergence, provided that the solution is sufficiently smooth. In the case of large-scale dumbbell and bead-spring chain calculations, an appropriate scaling of the number of grid points as a function of the number of beads N ensures, in the absence of excluded volume forces, that the cost of our algorithm is O(N) flops. Finally, we begin calculations in three dimensions with our SPH model. To this end, we solve in three dimensions the problem of Poiseuille flow between two infinite and parallel plates and the problem of Poiseuille flow in a rectangular infinitely long duct. In addition, we carry out three dimensional computations of confined flows of non-dilute polymer solutions with full hydrodynamic interaction and excluded volume forces.