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Auswahl der wissenschaftlichen Literatur zum Thema „Dynamique non linéaire multi-Échelles“
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Zeitschriftenartikel zum Thema "Dynamique non linéaire multi-Échelles"
Petitot, Jean. „Modèles morphodynamiques de segmentation spatiale“. Cahiers de géographie du Québec 42, Nr. 117 (12.04.2005): 335–47. http://dx.doi.org/10.7202/022761ar.
Der volle Inhalt der QuelleMartinerie, J., B. Renault, L. Pezard und C. Adam. „Analyse dynamique non linéaire de l'EEG en multi-électrodes et applications à l'épilepsie“. Neurophysiologie Clinique/Clinical Neurophysiology 27, Nr. 1 (Januar 1997): 68–69. http://dx.doi.org/10.1016/s0987-7053(97)89876-0.
Der volle Inhalt der QuelleBranci, Taieb, und Boualem Tiliouine. „Évaluation des méthodes réglementaires de détermination des déplacements sismiques par analyse dynamique non linéaire“. Canadian Journal of Civil Engineering 31, Nr. 3 (01.06.2004): 453–62. http://dx.doi.org/10.1139/l04-026.
Der volle Inhalt der QuelleGUERIN-RECHDAOUI, Sabrina, David DU PASQUIER, Anthony MARCONI, Erwan MICHELIN, Barabara ROBIN, Gregory LEMKINE, Sam AZIMI und Vincent ROCHER. „Biosurveillance des eaux de surface en agglomération parisienne – Résultats 2017-2019 en Seine, Marne et Oise“. Techniques Sciences Méthodes 6 (20.06.2023): 63–78. http://dx.doi.org/10.36904/tsm/20230663.
Der volle Inhalt der QuelleLivshits, Veniamin. „Mathematical methods used in the field of transport policy in the Soviet Union and in the CIS“. Les Cahiers Scientifiques du Transport - Scientific Papers in Transportation 27 | 1993 (31.03.1993). http://dx.doi.org/10.46298/cst.11929.
Der volle Inhalt der QuelleDroz, Christophe. „Modèles haute résolution pour l’analyse dynamique ultra-rapide des structures à géométrie périodique.“ e-journal of nondestructive testing 28, Nr. 9 (September 2023). http://dx.doi.org/10.58286/28508.
Der volle Inhalt der QuelleFlavia Irene, Santamaria,. „“Un estudio multimodal y dinámico de los conocimientos numéricos de estudiantes de primer grado”“. RIDAA Tesis Unicen, 27.09.2021. http://dx.doi.org/10.52278/2850.
Der volle Inhalt der QuelleDissertationen zum Thema "Dynamique non linéaire multi-Échelles"
Brochard, Guillaume. „Dynamique du fishbone ionique dans les tokamaks : théorie et simulations non-linéaires multi-échelles“. Thesis, Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAX002.
Der volle Inhalt der QuelleIn tokamak plasmas, fast particles generated by fusion reactions and by non-inductive heating techniques can resonantly interact with Magneto-Hydro-Dynamic (MHD) instabilities, potentially leading to their transport out of the plasma core. This topic is important in the context of burning plasmas, where the collisional relaxation of alpha particles is expected to compensate the energy losses. The resonant transport time of fast particles being much lower than their typical relaxation, these Kinetic-MHD instabilities can adversely impact the plasma energy balance, and therefore the fusion performance of future commercial reactors. In this thesis, we study the interaction of energetic ions with the internal kink mode, resulting in the onset of the fishbone instability. To this end, we use the nonlinear hybrid Kinetic-MHD code XTOR-K to simulate the nonlinear phases of the fishbone instability, during which fast particles are being transported. Firstly, the linear theory of the fishbone instability is re-derived, recovering similar expressions with Porcelli’s dispersion relation. Differences arise when considering deeply passing particles. A linear code has been implemented to solve non-perturbatively the fishbone dispersion relation obtained. Results with this code are consistent with those obtained from XTOR-K linear simulations, in terms of mode growth rates, rotations frequencies and resonant surfaces. This provides a linear verification of XTOR-K, that enables its use on complex equilibria and during nonlinear phases. Secondly, a parametric study is provided by XTOR-K regarding the alpha fishbone linear stability with equilibria relevant for the ITER 15 MA case. Our simulations show that this scenario is likely to be fishbone unstable for ITER relevant alpha particle densities. Finally, nonlinear results obtained with XTOR-K in low energy circular equilibria and in the ITER 15 MA case are presented. These results document the self-consistent dynamics of fast particles and MHD modes during one fishbone oscillation. Resonant fast particle transport is a common feature of these simulations, together with frequency chirping of the Kinetic-MHD mode. Differences between these simulations are discussed, as well as the nonlinear regime characterizing the observed mode based on existing theories. During one fishbone oscillation, in our different simulations, the overall alpha particle transport in the core plasma impacts from 5 to 10% of the initial population, which shows that the reduction of fusion performance due to the alpha-fishbone instability is limited. From these simulations, a mechanism explaining the nonlinear coupling between resonant particle transport and mode chirping is presented
Segneri, Marco. „Réduction exacte de la dynamique neurale à plusieurs échelles“. Thesis, CY Cergy Paris Université, 2020. http://www.theses.fr/2020CYUN1084.
Der volle Inhalt der QuelleThe work of this thesis is inspired by a new generation of neural mass models where the mean field equations are derived exactly starting from the microscopic ones for the neural population composed of QIF neurons. This innovative approach is based on recent results of statistical physics, which have shown the possibility of deriving exact macroscopic models for coupled phase oscillator networks. In more detail the thesis is structured as follows. In the first chapter we introduce the concept of phase oscillator and provide a detailed analysis of the Kuramoto model. We then show how it is possible to exactly reduce a system of N phase oscillators to a macroscopic system of low dimension. In this context two exact mean-field approaches have been developed. The first approach, developed in 1993 by Watanabe and Strogatz, is devoted to identical oscillators; while the second one,introduced in 2008 by Ott and Antonsen, describes the macroscopic dynamics of non-identical oscillators. In the second chapter we introduce the single QIF neuron model by providinga detailed study of its dynamics. We then define the network model of fullycoupled QIF neurons showing how to move from the microscopic descriptionof a population of QIF neurons with instantaneous synapses, correspondingto a system of N degrees of freedom, to the exact neural mass model withonly two degrees of freedom, that is in terms of the average firing rate andthe average membrane potential of the network.In the third chapter we examine two set-ups able to support collectivegamma oscillations: the pyramidal interneuronal network gamma (PING)and the interneuronal network gamma (ING). In both set-ups we observe theemergence of theta-nested gamma oscillations by driving the system with asinusoidal theta-forcing in proximity of a Hopf bifurcation. From our anal-ysis it emerges that the locked states are more frequent in the ING set-up.In agreement with the experiments, we find theta-nested gamma oscillationsfor forcing frequencies in the range [1:10] Hz, whose amplitudes grow proportionally to the forcing one and which are clearly modulated by the thetaphase. At variance with experimental findings, the gamma-power peak doesnot shift to higher frequencies by increasing the theta frequency. This effectcan be obtained, in our model, only by incrementing, at the same time, also the noise or the forcing amplitude.In the fourth chapter we study balanced sparse inhibitory networks of QIFneurons characterized by a finite synaptic time scale. As the main result,we show theoretically and numerically that a single inhibitory populationcan give rise to coexisting of slow and fast gamma rhythms correspondingto collective oscillations of a balanced spiking network. The slow and fastgamma rhythms are generated via two different mechanisms: the fast onebeing driven by the the coordinated tonic neural firing and the slow one byendogenous fluctuations due to irregular neural activity. We show that al-most instantaneous stimulations can switch the collective gamma oscillationsfrom slow to fast and vice versa.In the fifth chapter we consider a sparse balanced inhibitory network of QIFneurons with instantaneous synapses proving the transition from the asynchronous state to collective oscillations for large enough average connectivityby solving the associated Fokker-Planck equation. This result is in goodagreement with network simulations. Moreover we try to extend the OAtheory for sparse network by considering the Circulant Cumulant approxi-mation (CCs). In particular we consider CCs until the second cumulant,providing a four-dimensional system for the first and second cumulant. Thislow dimensional system is able to capture the transition from asynchronousstate to collective oscillations, however the discrepancy with the networksimulations suggests to consider major order of cumulants
Mamouri, Saïd. „Dynamique non linéaire des structures et des systèmes multi-corps“. Compiègne, 2000. http://www.theses.fr/2000COMP1259.
Der volle Inhalt der QuelleCharlemagne, Simon. „Dynamique non linéaire d’un assemblage d’oscillateurs : application au contrôle“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSET003.
Der volle Inhalt der QuelleNonlinear light oscillators can be used for performing vibratory passive control of structures undergoing unacceptable oscillations in terms of comfort and safety. The study of Nonlinear Energy Sinks (NES) has been especially subject to an important research effort since the beginning of the 2000s. Its essential nonlinearity enables it to achieve large-band energy pumping, which is a significant advantage in comparison with classical Tuned Mass Dampers. In this manuscript, nonlinear chains of oscillators coupled to linear systems under harmonic excitation are studied. The main goal is to understand the behavior of the whole system and find evidence of passive control abilities of such chains. First of all, a general analytical methodology is presented and applied to examples where single and multi-degree-of-freedom absorbers with cubic nonlinearities are linked to a linear oscillator. A modification of this approach by considering the chain in the form of a continuous approximation is then proposed. Finally, an experimental device composed of a single storey reduced-scale building coupled to a chain of eight nonlinear oscillators is investigated
Guskov, Mikhail. „Dynamique non-linéaire des systèmes multi-rotors : Etudes numérique et expérimentale“. Ecully, Ecole centrale de Lyon, 2007. http://bibli.ec-lyon.fr/exl-doc/mguskov.pdf.
Der volle Inhalt der QuelleModern trends in the progress of the machine design are to increase performances while reducing mass. This causes augmented loads in machine parts while the compliances grow as well. The resulting dynamical responses occur at accrued levels, putting forward nonlinear phenomena. The aim of this thesis is to study nonlinear structural dynamics, especially in view of application to multi-shaft aircraft engines rotordynamics. This problematics is investigated by theory and experiment. As for the theoretical development, we adress the dynamical response of strongly nonlinear systems under multi-frequency excitations. To this aim, the models of roller bearings are studied and implemented from the point of view of application to rotordynamics computations. In particular, these models take radial clearance and nonlinear contact stigness into account. In order to deal with multiple unbalance excitations which are present in multi-shaft rotor systems, we have elaborated a generalized harmonic balance approach so as to predict the resulting quasi-periodic motions. This work has been applied to a dual shaft test rig with an intershaft bearing built during this study. Methods of stability evaluation are also considered in view of extensions to quasi-periodic motions. In the experimental part of the work, we have designed and studied a dual shaft test rig with an intershaft bearing. The overall modal analysis of this rig matches a real aircraft engine's rotordynamical behavior. After the design and construction of the rig, several operational configurations have been tested. Firstly, we have studied the unbalance response of the machine under the nominal co-rotating conditions in order to validate the design approach and estimate the residual unbalance of the machine. Secondly, the counter-rotating operation has been tested. Finally, an additional mass has been mounted on one of the shafts. This has allowed to lower one of the modes into the operational range of the machine. The overall test results have enabled the observations of dynamical phenomena typical for the dual shaft dynamics both from the rotordynamical and nonlinear points of view : forward and backward whirls, quasi-periodic precession motion, resonance peaks distorsion and superharmonic response
Peillex, Guillaume. „Modélisations numériques multi-échelles du comportement dynamique de matériaux composites sous sollicitations tribologiques : cas des composites Carbone/Carbone utilisés en freinage aéronautique“. Lyon, INSA, 2007. http://www.theses.fr/2007ISAL0068.
Der volle Inhalt der QuelleIn order to understand the wear mechanism of composites used in aeronautic brakes, we need to dissociate the role of the mechanical phenomena from those of the thermal and physico-chemical phenomena. A two-scale composite is modelized numerically, using finite elements, and takes into account the mechanical aspect of dynamic contact with friction loading. Convergence is achieved thanks to a particular friction law. A multi-scale approach, by homogenization allows to dissociate the influence of the macroscopic scale, which determines the possible vibration modes, from the one of the mesoscopic scale, which chooses the mode that is really expressed. A damage scenario, based on local stress evaluation for each scale, is set up and joins experimental observations. The model also allows to characterize the influence of some manufacturing process parameters over its tribological behavior
Guskov, Mikhail. „Dynamique non-linéaire des systèmes multirotors. Etudes numérique et expérimentale“. Phd thesis, Ecole Centrale de Lyon, 2007. http://tel.archives-ouvertes.fr/tel-00438353.
Der volle Inhalt der QuelleMuzard, Philippe. „Etude du comportement dynamique linéaire et non-linéaire d'un rotor d'hélicoptère : Application au couplage rotor-fuselage“. Ecully, Ecole centrale de Lyon, 1994. http://bibli.ec-lyon.fr/exl-doc/TH_T1582_pmuzard.pdf.
Der volle Inhalt der QuelleThe development of computing power and optimisation methods used by the engineers leads to a better design of structures. It has for first consequence the appearance of non linear phenomena affecting the dynamic behaviour which can modify in a large part the linear response. The first part of this work deals also with the insertion of non linearities in the modelling of helicopter rotor dynamics. We will show that non linearities can't be always neglected and leads sometimes to chaotic behaviour and even instability. A particular analysis of these phenomena is made using well-known methods - Volterra's series, normal form theory - in order to identify the main non linear parameters. The original aspect of this work lies in the application of non linear analysis to a multi-dimensional system which is close to reality. We will study afterwards the coupling between two linear structures. In the case of helicopter, the particularity is that the rotor is strongly gyroscopic. We will use a modal approach of the fuselage to simplify the analysis. Two directions will be explored. A simplified model permits us to identify the coupled degrees of freedom. A second modelling, taking into account numerous aerodynamic effects, will be used as a tool for conception and design of helicopters. At last, we will study an unstable coupling between rotor and fuselage through particular mechanical organs
Voslion, Thibaut. „Instabilité de déchirement multiple et cisaillement fluide dans un plasma chaud magnétisé“. Aix-Marseille 1, 2010. http://www.theses.fr/2010AIX11121.
Der volle Inhalt der QuelleThis thesis process a multi-sacle interaction study about Double tearing mode and shear flow instability in Tokamak. The study is made to show the influence of a shear flow on global reconnection, nonlinear phenomena linked to the double tearing mode, and harmful for plasma confinement in tokamaks. Both theoretical and numerical studies on double tearing mode in presence of a shear flow, which can trigger Kelvin-Helmholtz instability, is performed in the framework of reduced and resistive magnetohydrodynamics (MHD). The systematic study of linear and nonlinear effects is performed as a function of relevant parameters. Thus, different dynamics are obtained, with and without turbulence depending on parameters. We find that even in presence of a strong turbulence, the double tearing dynamics leads to the global reconnexion if resonnant surfaces are close enough. However, the global reconnexion may be significantly delayed in presence of a shear flow
Leprovost, Nicolas. „Influence des petites échelles sur la dynamique à grande échelle en turbulence hydro et magnétohydrodynamique“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00007809.
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