120 research outputs found
Wave propagation in a waveguide containing restrictions with circular arc shape
No full textInternational audienceA multimodal method is used to analyze the wave propagation in waveguides containing restrictions (or corrugations) with circular arc shapes. This is done using a geometrical transformation which transforms the waveguide with complex geometry in the real space to a straight waveguide in the transformed space, or virtual space. In this virtual space, the Helmholtz equation has a modified structure which encapsulates the complexity of the geometry. It is solved using an improved modal method, which was proposed in a paper by A. Maurel, J.-F. Mercier, and S. Félix [Proc. R. Soc. A 470, 20130743 (2014)], that increases the accuracy and convergence of usual multimodal formulations. Results show the possibility to solve the wave propagation in a waveguide with a high density of circular arc shaped scatterers
Empirical mode decomposition profilometry: small-scale capabilities and comparison to Fourier transform profilometry
Get PDFWe present the empirical mode decomposition profilometry (EMDP) for the analysis of fringe projection profilometry (FPP) images. It is based on an iterative filter, using empirical mode decomposition, which is free of spatial filtering and adapted for surfaces characterized by a broadband spectrum of deformation. Its performances are compared to Fourier transform profilometry, the benchmark of FPP. We show both numerically and experimentally that using EMDP improves strongly the profilometry small-scale capabilities. Moreover, the height reconstruction distortion is much lower: the reconstructed height field is now both spectrally and statistically accurate. EMDP is thus particularly suited to quantitative experiments.Fil: Lagubeau, Guillaume. Universidad de Santiago de Chile; ChileFil: Cobelli, Pablo Javier. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Bobinski, Tomas. Centre National de la Recherche Scientifique. Laboratoire Pmmh-umr 7636; FranciaFil: Maurel, Agnes. Institut Langevin, Umr Cnrs; FranciaFil: Pagneux, Vincent. Laboratoire D'acoustique, Univ. Maine Umr Cnrs 6613; FranciaFil: Petitjeans, Philippe. Centre National de la Recherche Scientifique. Laboratoire Pmmh-umr 7636; Franci
Documents numériques et transmodalité. Transposition automatique à l'oral des structures visuelles de texte
No full text@article{RN-MAUREL-2006, author = {Maurel, Fabrice and Mojahid, Mustapha and Vigouroux, Nadine and Virbel, Jacques}, title = {Documents numériques et transmodalité. Transposition automatique à l'oral des structures visuelles de texte}, journal = {Document numérique}, publisher = {Hermès}, address = {http://www.editions-hermes.fr}, year = {2006}, volume = {9}, number = {1}, pages = {25--42}, language = {français}, keywords = {}, note = {ISBN 2-7462-1401-6} }National audienceConsidered for a long time as ornamental, the texts visual structure becomes nowadays a full object of investigation in various disciplines. We are interested in the utility oh these aspects of documents and, if the need arises, their usability, within the framework of their oral transposition by Text-To-Speech systems (TTS). We propose an Oralisation system which leads to text representations directly interpretable by TTS. We focus on a reformulation-based oralisation model for texts written to be silently read (MORTELS) in order to render some signifying parts of the texts often "forgotten" by synthesis systemsLongtemps considérée comme ornementale, la structure visuelle des textes est aujourd'hui abordée comme un objet d'étude à part entière dans diverses disciplines. Nous nous intéressons à son utilité et, le cas échéant, son utilisabilité, dans le cadre de la transposition à l'oral par des systèmes de synthèse de la parole à partir de textes (TTS). Nous proposons un système d'oralisation qui conduit à des représentations du texte interprétables par un TTS. Nous focalisons sur un modèle d'oralisation par reformulation des textes écrits pour être lus silencieusement (MORTELS) dont l'objectif est de rendre « articulables » certaines parties signifiantes des textes souvent « oubliées » par les systèmes actuels
Documents numériques et transmodalité. Transposition automatique à l'oral des structures visuelles de texte
No full text@article{RN-MAUREL-2006, author = {Maurel, Fabrice and Mojahid, Mustapha and Vigouroux, Nadine and Virbel, Jacques}, title = {Documents numériques et transmodalité. Transposition automatique à l'oral des structures visuelles de texte}, journal = {Document numérique}, publisher = {Hermès}, address = {http://www.editions-hermes.fr}, year = {2006}, volume = {9}, number = {1}, pages = {25--42}, language = {français}, keywords = {}, note = {ISBN 2-7462-1401-6} }National audienceConsidered for a long time as ornamental, the texts visual structure becomes nowadays a full object of investigation in various disciplines. We are interested in the utility oh these aspects of documents and, if the need arises, their usability, within the framework of their oral transposition by Text-To-Speech systems (TTS). We propose an Oralisation system which leads to text representations directly interpretable by TTS. We focus on a reformulation-based oralisation model for texts written to be silently read (MORTELS) in order to render some signifying parts of the texts often "forgotten" by synthesis systemsLongtemps considérée comme ornementale, la structure visuelle des textes est aujourd'hui abordée comme un objet d'étude à part entière dans diverses disciplines. Nous nous intéressons à son utilité et, le cas échéant, son utilisabilité, dans le cadre de la transposition à l'oral par des systèmes de synthèse de la parole à partir de textes (TTS). Nous proposons un système d'oralisation qui conduit à des représentations du texte interprétables par un TTS. Nous focalisons sur un modèle d'oralisation par reformulation des textes écrits pour être lus silencieusement (MORTELS) dont l'objectif est de rendre « articulables » certaines parties signifiantes des textes souvent « oubliées » par les systèmes actuels
Improved multimodal method for the acoustic propagation in waveguides with a wall impedance and a uniform flow
No full textInternational audienc
Propagation of guided waves through weak penetrable scatterers
No full textInternational audienceThe scattering of a scalar wave propagating in a waveguide containing weak penetrable scatterers is inspected in the Born approximation. The scatterers are of arbitrary shape and present a contrast both in density and in celerity (or bulk modulus), a situation that can be translated in the context of SH waves, water waves or TE/TM polarized electromagnetic waves. For small size of inclusions compared to the waveguide height, analytical expressions of the transmission and reflexion coefficients are derived, and compared to result of direct numerical simulations. The cases of periodically and randomly distributed inclusions are considered in more details, and compared with un- bounded propagation through inclusions. Comparisons with previous results valid in the low frequency regime are proposed
Propagation of guided waves in a non-uniform acoustic waveguide
No full textInternational audienceWe study the time harmonic propagation of acoustic waves in a waveguide with varying cross section. This is done using a multimodal approach. The modal components are expressed thanks to an integral representation (Lipmann Schwinger representation) that is used to iterate the Born approximation. We compare the classical approach in which the infinite sum of modes is truncated in the practice to a new formalism in which the sum of modes is finite and an extra mode is artificially added. This method has been shown to ensure a better convergence because the additional mode allows a better approximation of the boundary condition at the walls. Numerical calculations are proposed and compared to direct finite element simulations to validate the iterated Born approximation. Analytical solutions are proposed in the first Born approximation and compared to classical results for the low frequency regime
Second Order Homogenization of Subwavelength Stratified Media Including Finite Size Effect
No full textInternational audienc
- …
