Littérature scientifique sur le sujet « Ondes propagatives »
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Articles de revues sur le sujet "Ondes propagatives"
Wang, Yafei, Koji Yamazaki et Yasushi Fujiyoshi. « The Interaction between Two Separate Propagations of Rossby Waves ». Monthly Weather Review 135, no 10 (1 octobre 2007) : 3521–40. http://dx.doi.org/10.1175/mwr3486.1.
Texte intégralGuesmia, Aissa. « Non-exponential and polynomial stability results of a Bresse system with one infinite memory in the vertical displacement ». Nonautonomous Dynamical Systems 4, no 1 (26 octobre 2017) : 78–97. http://dx.doi.org/10.1515/msds-2017-0008.
Texte intégralJabiri, Ayoub, Abdelali Yacoubi et Mhammed El Allami. « Plotting Lamb waves dispersion curves of an aluminum plate by the Semi-Analytical Finite Element (SAFE) method and comparison with analytical curves ». ITM Web of Conferences 48 (2022) : 02006. http://dx.doi.org/10.1051/itmconf/20224802006.
Texte intégralNascimento, Ana Rosa Peixoto, et Rosa de Lima Ramos Mariano. « Cancro bacteriano da videira : etiologia, epidemiologia e medidas de controle ». Ciência Rural 34, no 1 (février 2004) : 301–7. http://dx.doi.org/10.1590/s0103-84782004000100050.
Texte intégralNoor, Saima, Ma’mon Abu Hammad, Rasool Shah, Albandari W. Alrowaily et Samir A. El-Tantawy. « Numerical Investigation of Fractional-Order Fornberg–Whitham Equations in the Framework of Aboodh Transformation ». Symmetry 15, no 7 (3 juillet 2023) : 1353. http://dx.doi.org/10.3390/sym15071353.
Texte intégralZhang, Guoqiang, Zhenya Yan et Li Wang. « The general coupled Hirota equations : modulational instability and higher-order vector rogue wave and multi-dark soliton structures ». Proceedings of the Royal Society A : Mathematical, Physical and Engineering Sciences 475, no 2222 (février 2019) : 20180625. http://dx.doi.org/10.1098/rspa.2018.0625.
Texte intégralSpinelli, Victor Mouzinho, Luis Iram Coutinho Ulguim, Ilisandra Zanandrea, Valmor João Bianchi, Willian Silva Barros, Luís Eduardo Panozzo, Moisés Botelho Fabião et Deivid Araújo Magano. « Teste de germinação em Seedlings de porta-enxertos de pessegueiro ». OBSERVATÓRIO DE LA ECONOMÍA LATINOAMERICANA 21, no 8 (25 août 2023) : 9804–16. http://dx.doi.org/10.55905/oelv21n8-106.
Texte intégralGranot, Er'el. « Analytical Solutions for the Propagation of UltraShort and UltraSharp Pulses in Dispersive Media ». Applied Sciences 9, no 3 (4 février 2019) : 527. http://dx.doi.org/10.3390/app9030527.
Texte intégralCastellanos, Luis M., Francisco Lopez et Erick Reyes - Vera. « Metamateriales : principales características y aplicaciones ». Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 40, no 156 (3 octobre 2016) : 395. http://dx.doi.org/10.18257/raccefyn.345.
Texte intégralSilva, Tamires Maria De Lima, et Emilio Augusto Gomes de Oliveira. « “Maquiagem verde” na comunicação gráfica de condomínios residenciais em Caruaru-Pernambuco ». AtoZ : novas práticas em informação e conhecimento 2, no 2 (31 décembre 2013) : 116. http://dx.doi.org/10.5380/atoz.v2i2.41326.
Texte intégralThèses sur le sujet "Ondes propagatives"
Leblond, Gregory. « Etude et développement d'un micro-spectromètre à ondes guidées contra-propagatives ». Troyes, 2009. http://www.theses.fr/2009TROY0031.
Texte intégralSWIFTS (Stationary Waves Integrated Fourier Transform Spectrometer) is a new concept of Fourier Transform spectrometry that opens the way to high-resolution ultra-compact spectrometers. This integrated spectrometer is based on the direct near-field probing of the optical source’s Fourier Interferogram. To obtain the most compact structure a Guided Interferogram (GI) is created into an optical integrated waveguide thanks to a counterpropagative phenomenon. Once the stationary GI created, the challenge is to read this useful information confined into the waveguide. The idea is to sample the GI by embedding a comb of nano-probes in the waveguide’s near-field. These nano-elements scatter the GI’s near-field profile towards a detector array placed in far-field. The incident light spectrum can be recovered by Fourier Transform of the collected signal. We focused our work on the simulation of one nano-probe. This study is critical: the scattering light has to go towards the detector without disturbing the useful information confined into the waveguide. To study this phenomenon, we developed the Fourier Modal Method with PML (Perfectly Matched Layer). Then, we developed specific tools to characterize the scattering light of a nano-element embedded in the waveguide’s near-field. This numerical method is also adapted to the whole spectrometer, including many nano-probes elements. We validated simulation work by an experimental realization
Vince, Jean-Marc. « Ondes propagatives dans des systèmes convectifs soumis à des effets de tension superficielle ». Paris 7, 1994. http://www.theses.fr/1994PA077345.
Texte intégralMegnien, Jean-Louis. « Evaluation in vivo des contraintes de cisaillement et des ondes propagatives en hemodynamique arterielle ». Paris 7, 1998. http://www.theses.fr/1998PA077105.
Texte intégralGrenier, Muriel. « Attraction d'ondes pour des systèmes à résonance d'ondes contra-propagatives ». Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00696097.
Texte intégralRazo, López Luis Alberto. « Localisation des ondes électromagnétiques au-delà d'Anderson : rôle des corrélations, des symétries et de la topologie ». Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ5013.
Texte intégralIn a broad sense, the term wave localization refers to a phenomenon where waves are spatially confined in small regions of the space without any bounding material barriers.In this Thesis, we investigate (analytically, numerically and experimentally) different physical collective mechanisms to spatially localize, and therefore, to control electromagnetic waves. Specifically, we focus on the role of uncorrelated and correlated potentials, as well as of topological effects to achieve wave confinement. Analytical and numerical studies are accomplished in the framework of a recent approach in the modeling of Anderson localization called localization landscape theory. On the other hand, experiments are performed using a microwave platform composed by small dielectric cylinders placed inside a cavity made of two metallic plates. The cavity implements a propagative wave system, where we can efficiently control the local permittivity by means of the cylinders acting as scatterers, or as an analogic tight-binding system, where, in this case, the dielectric cylinders play the role of resonators.First, we extend the scope of the localization landscape approach to a wide class of one and two dimensional tight-binding systems in the presence of uncorrelated disorder, where localized eigenfunctions appear in both band-edges. We demonstrate how the landscape theory is able to predict accurately not only the locations, but also the energies of localized eigenfunctions in the low- and high-energy regimes. Later, by using our experimental cavity as a propagative system, we perform microwave transport experiments in two dimensional planar arrays. Experiments are carried out on a disordered lattice and on an aperiodic Vogel spiral from where we characterize the electromagnetic modal structures in real space. Our results reveals that aperiodic systems can carry a rich variety of long-lived modes—with Gaussian, exponential, and power law spatial decays—which are able to survive even in a three-dimensional environment. This is supported by different transport quantities such as the density of states, the characteristic decay time, and the Thouless conductance that are also experimentally accessible. On the contrary, we show that the eigenstates in traditional disordered media are always limited to exponential radial decays with leaking features beyond two-dimensions.Finally, we use the experimental tight-binding configuration to investigate the propagation of topological helical states. Particularly, we experimentally analyze a set of honeycomb-like structures built using a triangular lattice with an hexagonal unit cell, which are characterized by the Z_2 topological invariant. By recovering the modal structure in real space and the density of states, our results reveal the possibility to open a topological gap, dwelt by edge states that lives in the border of the structure.We demonstrate the unidirectional counterpropagative features of such helical edge states.Taken together, our results demonstrate that it is possible to model, control and localize electromagnetic waves not only within, but beyond Anderson's conception. Thanks to the crossroads we have taken, we have mapped out an itinerary that brings us closer to the main avenue leading perhaps to Anderson localization of three dimensional electromagnetic waves
Zhou, Changwei. « Approche couplée propagative et modale pour l'analyse multi-échelle des structures périodiques ». Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0040/document.
Texte intégralStructural dynamics can be described in terms of structural modes as well as elastic wave motions. The mode-based methods are widely applied in mechanical engineering and numerous model order reduction (MOR) techniques have been developed. When it comes to the study of periodic structures, wave description is mostly adopted where periodicity is fully exploited based on the Bloch theory. For complex periodic structures, several MOR techniques conducted on wave basis have been proposed in the literature. In this work, a wave and modal coupled approach is developed to study the wave propagation in periodic structures. The approach begins with the modal description of a unit cell (mesoscopic scale) using Component Mode Synthesis (CMS). Subsequently, the wave-based method -Wave Finite Element Method (WFEM) is applied to the structure (macroscopic scale). The method is referred as “CWFEM” for Condensed Wave Finite Element Method. It combines the advantages of CMS and WFEM. CMS enables to analyse the local behaviour of the unit cell using a reduced modal basis. On the other hand, WFEM exploits fully the periodic propriety of the structure and extracts directly the propagation parameters. Thus the analysis of the wave propagation in the macroscopic scale waveguides can be carried out considering the mesoscopic scale behaviour. The effectiveness of CWFEM is illustrated via several one-dimensional (1D) periodic structures and two-dimensional (2D) periodic structures. The criterion of the optimal reduction to ensure the convergence is discussed. Typical wave propagation characteristics in periodic structures are identified, such as pass bands, stop bands, wave beaming effects, dispersion relation, band structure and slowness surfaces...Their proprieties can be applied as vibroacoustics barriers, wave filters. CWFEM is subsequently applied to study wave propagation characteristics in perforated plates and stiffened plate. A homogenization method to find the equivalent model of perforated plate is proposed. The high frequency behaviours such as wave beaming effect are also predicted by CWFEM. Three plate models with different perforations are studied. Experimental validation is conducted on two plates. For the stiffened plate, the influence of internal modes on propagation is discussed. The modal density in the mid- and high- frequency range is estimated for a finite stiffened plate, where good correlation is obtained compared to the mode count from modal analysis
Lalloz, Samy. « De la diffusion à la propagation d'ondes en magnétohydrodynamique bas-Rm : études théorique et expérimentale ». Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALI020.
Texte intégralThe thesis aims to clarify the conditions for Alfvén waves to propagate in a closed liquid metal domain. A first part of the research work presented is dedicated to a linear study of Alfvén waves in the low-Rm approximation and under the inertia-less limit. The second part is the experimental investigation of an electrically-induced oscillating flow subjected to an axial, static and uniform magnetic field and confined between two electrically insulating and no-slip horizontal walls.The theoretical study is itself split into two sub-parts. The first one aims to discuss the dispersion relation which contains the Alfvén wave dynamics. It presents the consequences of (mechanical and magnetic) gradients perpendicular to the imposed magnetic field. As such transverse gradients tend to impede the wave propagation. In the second sub-part an axisymmetric vortex confined between to electrically insulated and no-slip horizontal walls is magnetically forced at a given frequency. This forcing is radially dependent so as to study the impact of transverse gradients on the flow dynamics. A semi-analytical investigation of the flow dynamics is again carried out in the low-Rm approximation and under the inertia-less limit. This investigation is performed by varying the forcing frequency and the magnetic field intensity. This brings to emphasize two very distinct regimes for the oscillating vortex:- an oscillating-diffusive regime governed by the competition between pseudo-diffusive effects of the Lorentz force and the unsteady term of the momentum- a truly propagative regime, obtained for higher forcing frequencies, found definitelygoverned by Alfvén waves.The study also highlights how the propagative regime can be affected by transverse gradients. In addition to over-damping the waves, transverse gradients are found to modify the natural frequencies for which wave resonance peaks result from the superimposition of incident and reflected waves in the container.Beside this theoretical work, a setup has been designed in order to experimentally investigate the dynamics of oscillating flows under a strong magnetic field (up to 10T). A flow was forced in a cuboid vessel 15 cm x 15 cm x 10 cm by means of AC currents injected through a cartesian grid of four electrodes located at the bottom plate. Using instrumentation based on the measurement of local electric potential differences at the top and bottom horizontal (Hartmann) plates, we validate model's prediction. More precisely, a propagative dynamics in the presence of transverse gradients is recovered. The oscillating-diffusive regime is also recovered from experiments performed at small enough forcing frequency.In addition to results obtained at the forcing frequency, a first insight of signals obtained at other frequencies is shown. Frequency peaks obtained, eg the harmonics of the forcing frequency, are demonstrated not to be explained by a linear approach. We suggest that Alfvén wave non-linear interactions are a good candidate to explain these peaks. A preliminary study further shows that peaks at the first harmonic are likely to be Alfvén waves
Nascimento, Rangel Ferreira do. « Propagação de ondas usando modelos de elementos finitos de fatias de guias de ondas estruturais ». [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265401.
Texte intégralTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Esta tese estuda e investiga o problema de propagação de ondas em estruturas periódicas usando o método de elemento espectral, a relação entre a matriz dinâmica e a matriz de transferência é mostrada para alguns casos, tais como, viga, barra, placa de Levy e modelo de Minddlin Hermman. A partir destas teorias, o método de propagação de ondas usando um modelo de elementos finitos de uma fatia do guia de ondas, WFEM é apresentado e o problema de prever os modos de propagação e os números de onda correspondentes. O objetivo deste trabalho é mostrar que usando o método WFEM e uma fatia do guia de onda modelado com elementos finitos sólido é possível construir elementos finitos espectrais para ser usado em guias de ondas homogêneos sem precisar de malha de refinamento. Tais elementos podem ser usados para modelar guias de ondas com seção transversal constante. A matriz de rigidez dinâmica para o elemento de barra elementar e para o elemento de viga de Euler Bernoulli são obtidos usando a formulação espectral padrão e obtidas usando uma fatia do guia de onda modelado pelo método FEM, são mostrados resultados do método proposto.
Abstract: This thesis, studies and investigates wave propagation problem in periodic structures using the spectral element method, the relation between the dynamic matrix and the transfer matrix is shown for some cases, such as, beam, bar, Levy plate and Mindlin-Herrmann's model. From these theories, the Wave Finite Element Method, WFEM is presented and the problem of predicting the wave propagation modes and the respective wavenumbers. The purpose of this work is to show that using the WFEM method and a slice of the waveguide modeled with solid finite elements, it is possible to develop spectral finite elements to be used in long homogeneous waveguides without the need of mesh refinement. Such elements can be used to model waveguides with constant cross section and long spans. The dynamic stiffness matrix of a simple rod and Bernoulli Euler beam element obtained using the standard spectral formulation and obtained via the FEM model of a slice are shown to be similar, thus validating the proposed method.
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
Lerbet, François. « Processus cohérents et temps de relaxation dans des verres magnétiques à très basse température : étude par acoustique propagative ». Paris 11, 1987. http://www.theses.fr/1987PA112026.
Texte intégralWe study the acoustical properties of amorphous magnetic insulators for varying concentration of magnetic impurities between 10,1 % at. And 1,5 % at. . We use a method of propagating wave between 10 MHz and 1000 MHz at very low temperature (from 10 mK up to 10 K) and for magnetic fields up to 60 kOe. With the choice of Ho3+ ions as magnetic impurities, we have been able to point out low energies activated movements of magnetic entities (V 5 K) which are not related at the spin glass transition. The study of tunnelling states in these glasses shows that their classical description in the insulators is no more valid here and that we must take into account the "direct" interaction between tunnelling states and magnetic impurities
Camargo, Alexandre William 1989. « Análise de um esquema de diferenças finitas com operador espacial adaptativo ». [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307613.
Texte intégralDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica
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Resumo: A base fundamental do modelamento sísmico é a equação da onda acústica, que para meios com velocidade variável exige métodos numéricos eficientes para encontrar a solução da equação. O Método de Diferenças Finitas (MDF) é muito usado para obter a solução da equação da onda, pois é de fácil implementação. Uma vez garantindo a convergência do método a solução aproximada é confiável. Contudo, os esquemas utilizados pelo MDF ou utilizam um comprimento longo para os operadores da derivada espacial ou precisam ter uma malha suficientemente densa, isto é, ter passos pequenos para garantir uma solução precisa, porém, isso requer o cálculo de muitas operações na fórmula recursiva do método. Nesta dissertação, analisamos um esquema do MDF que utiliza comprimentos adaptativos para o operador da derivada espacial assumindo uma malha computacional com o passo fixo. O critério que escolhe esses comprimentos depende da velocidade do meio. Pela relação entre o comprimento e a velocidade, o método escolhe um comprimento longo em regiões de baixa velocidade e um comprimento curto nas regiões de alta velocidade. Os testes numéricos comprovaram que o MDF com o esquema de comprimentos adaptativos obtém uma solução com uma precisão similar à solução do MDF com o esquema que usa somente comprimentos longos, mas o esquema de comprimento adaptativo realiza um número de operações menor na fórmula de recursão
Abstract: The fundamental base of seismic modeling is the acoustic wave equation that for a medium with variable velocity require efficients numerical methods to find the equation solution. The Finite Difference Method (FDM) is widely used to get the solution of the wave equation because the computational implementation is very easy. Ensuring the con- vergence of the method, the approximate solution is reliable. However, the schemes used by FDM either need a high length to the operator of the spatial derivative or take a sufficiently dense mesh, that is, the grid is small to ensure an accurate solution. But this requires the calculus of many operations in the recursion formula. In this dissertation, we analyzed a scheme of the FDM that use adaptive lengths to the operator of the spatial de- rivative assuming a fixed grid. The criterion to choose the lengths depend on the velocity of the medium. Thereby, in regions of low velocity a long length is used and in regions of high velocity a short length is enough. The numerical tests show that FDM with the adaptive length scheme obtains a solution with a similar accuracy to the solution of the FDM with the long length scheme, but performs a smaller number of operations in the recursion formula
Mestrado
Matematica Aplicada
Mestre em Matemática Aplicada
Actes de conférences sur le sujet "Ondes propagatives"
Roth, Michael, et Felix Gantenbein. « Model-Based Hazard an Propagation Assessment of Product Changes ». Dans ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59137.
Texte intégralBao, Yang, et Jiming Song. « Kriging Accelerated MAPoD Analysis of Surface Flaws with Eddy Current Simulation Yang Bao1 and Jiming Song2 ». Dans ASNT Research Symposium 2023. The American Society for Nondestructive Testing Inc., 2023. http://dx.doi.org/10.32548/rs.2023.041.
Texte intégralBrasselet, Sophie, et Joseph Zyss. « Control of The Photoinduced Micro-Patterning of Nonlinear Organic Thin Films : From Molecular to Photonic Engineering ». Dans Organic Thin Films for Photonic Applications. Washington, D.C. : Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.fb.1.
Texte intégralYang, Liang, Zhiyang Chen, Junhua Gu et Yuanfang Guo. « Dual Self-Paced Graph Convolutional Network : Towards Reducing Attribute Distortions Induced by Topology ». Dans Twenty-Eighth International Joint Conference on Artificial Intelligence {IJCAI-19}. California : International Joint Conferences on Artificial Intelligence Organization, 2019. http://dx.doi.org/10.24963/ijcai.2019/564.
Texte intégral