In this paper, we present an efficient numerical method to calculate the frequency and time respo... more In this paper, we present an efficient numerical method to calculate the frequency and time responses of the field scattered by an object buried between two random rough surfaces. This method is called Generalized PILE (GPILE) method because it extends the PILE method which considers only two surfaces or an object buried under a surface. The GPILE method solves rigourously the Maxwell equations by using a simple matrix formulation. The obtained results have a straightforward physical interpretation and allow us to investigate the influence of the object buried between the two rough surfaces. We distinguish the primary echo of the upper surface, the multiple echoes coming from the lower surface and those arising from the object. The GPILE method is applied to simulate the Ground Penetrating Radar (GPR) signal at nadir. The resulting time response helps the user to detect the presence of the object buried between the two random rough surfaces.
National audienceCe papier présente notre travail sur l’implémentationd’un dispositif de vérifica... more National audienceCe papier présente notre travail sur l’implémentationd’un dispositif de vérification en ligne pour la surveillanced’une application qui s’exécute sur un SoPC (System onProgrammable Chip). Le but est de vérifier que l’exécutionde l’application est conforme à un ensemble depropriétés. Cette vérification est réalisée par des moniteursimplémentés sur le FPGA du SoPC. Ces moniteurssont générés à partir de spécifications qui traduisent lecomportement du système exprimé dans le langage formelptLTL (past-time Linear Temporal Logic)
National audienceCette communication pr´esente le champ diffusé par unesurface de mer rugueuse ca... more National audienceCette communication pr´esente le champ diffusé par unesurface de mer rugueuse calculé par l’approximation de l’optiquephysique (OP). De plus, pour tenir compte de l’effet de conduitau-dessus de la surface de mer, l’indice de réfraction n’est pasconsidéré comme constant en fonction de la hauteur mais suitune loi affine. Ainsi, pour résoudre conjointement le problème dediffraction et de propagation, tout d’abord le champ est propagéà l’aide de la fonction de Green associée à l’indice de réfraction,puis l’OP est itérée pour calculer la contribution du champdiffracté associé à chacun des rebonds. L’approche est alorsvalidée par une méthode de référence basée sur la méthode desmoments. De plus, avec l’OP, le coefficient de diffusion cohérentest calculé analytiquement, permettant ainsi de généraliser lecoefficient de réflexion d’Ament à n rebonds. Ce coefficient estcouramment appliqué dans une méthode de type “ParabolicWaveEquation (PWE)” et résolue par un schéma de type ...
HAL (Le Centre pour la Communication Scientifique Directe), Jun 12, 2015
International audienceIn civil engineering, ground penetrating radar is widely used for road pave... more International audienceIn civil engineering, ground penetrating radar is widely used for road pavement surveys. The layer thickness is deduced from both the time delays of the backscattered echoes and the permittivity of the layers. In this paper, the influence of the interface roughness is studied. A modified ESPRIT algorithm is proposed for estimating the time delay, the interface roughness and the permittivity of layers from the received echoes. The algorithm is tested on simulated data obtained from the propagation inside layer expansion (PILE) method. Numerical examples are provided to demonstrate the performance of the algorithm
Cet article presente une methode haute frequence, basee sur l’approximation de l’Optique Physique... more Cet article presente une methode haute frequence, basee sur l’approximation de l’Optique Physique (OP), pour evaluer les courants sur une surface de mer rugueuse parfaitement conductrice dans le domaine Radar des microondes. Ainsi, a partir de la connaissance de la fonction de Green du conduit (milieu stratifie decrit par un modele lineaire du profil d’indice de refraction au carre) present au-dessus de la mer, ces courants sont rayonnes a l’aide du principe d’Huygens pour calculer le champ diffuse dans le conduit. A cause du phenomene de refraction, ce champ va produire un courant sur la surface (second rebond) qui est a nouveau evalue par l’OP. Ce processus est ainsi reitere. De plus, cette methode sera validee avec une methode rigoureuse basee sur la methode des moments et acceleree par la Forward-Backward.
2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021
In this paper, we study the electromagnetic scattering by an object buried inside a layer with tw... more In this paper, we study the electromagnetic scattering by an object buried inside a layer with two rough interfaces. We construct a rigorous mathematical model by using the integral equations in the frequency domain and discretize these equations by the method of moments. To reduce the complexity of the inversion of the resulting impedance matrix, we derive a rapid method based on the Propagation-Inside-Layer Expansion (PILE) algorithm, which has already proven its efficiency.
This paper studies the coherent scattering from random rough layers, made up of two uncorrelated ... more This paper studies the coherent scattering from random rough layers, made up of two uncorrelated random rough surfaces. An analytical asymptotic model, based on the scalar Kirchhoff-tangent plane approximation, is proposed. The results are compared with a rigorous electromagnetic method called PILE (Propagation-Inside-Layer-Expansion) for studying the validity of the model. This approach is applied to road survey by GPR at nadir.
This paper presents new results of a simulation of radar backscatter from oil slick areas on a re... more This paper presents new results of a simulation of radar backscatter from oil slick areas on a real three-dimensional sea surface, based on a physical hydrodynamic model of surface wave damping in the presence of oil films, the local equilibrium model (MLB). To solve this problem, the modelling was carried out by using the first-order small-slope approximation (SSA1) model. It presents the advantage of having a very good compromise between rapidity and accuracy of the calculation. The choice of the model is justified by solving the two-dimensional problem with several asymptotic methods and further comparing the results with a rigorous numerical method, based on the Method of Moments (MoM). Two approaches called “thin-layer” (TL) and “classical” were used to deal with the double layer (air/oil/sea) problem. The TL approach assumes that this double-layer problem can be seen locally as a Fabry–Pérot interferometer, which implies that the Kirchhoff-tangent plane approximation (KA) is v...
This paper addresses the subject of electromagnetic wave scattering in layered media, thus coveri... more This paper addresses the subject of electromagnetic wave scattering in layered media, thus covering the recent progress achieved with different approaches. Existing theories and models are analyzed, classified, and summarized on the basis of their characteristics. Emphasis is placed on both theoretical and practical application. Finally, patterns and trends in the current literature are identified and critically discussed.
In this paper, we present an efficient numerical method to calculate the frequency and time respo... more In this paper, we present an efficient numerical method to calculate the frequency and time responses of the field scattered by an object buried between two random rough surfaces. This method is called Generalized PILE (GPILE) method because it extends the PILE method which considers only two surfaces or an object buried under a surface. The GPILE method solves rigourously the Maxwell equations by using a simple matrix formulation. The obtained results have a straightforward physical interpretation and allow us to investigate the influence of the object buried between the two rough surfaces. We distinguish the primary echo of the upper surface, the multiple echoes coming from the lower surface and those arising from the object. The GPILE method is applied to simulate the Ground Penetrating Radar (GPR) signal at nadir. The resulting time response helps the user to detect the presence of the object buried between the two random rough surfaces.
National audienceCe papier présente notre travail sur l’implémentationd’un dispositif de vérifica... more National audienceCe papier présente notre travail sur l’implémentationd’un dispositif de vérification en ligne pour la surveillanced’une application qui s’exécute sur un SoPC (System onProgrammable Chip). Le but est de vérifier que l’exécutionde l’application est conforme à un ensemble depropriétés. Cette vérification est réalisée par des moniteursimplémentés sur le FPGA du SoPC. Ces moniteurssont générés à partir de spécifications qui traduisent lecomportement du système exprimé dans le langage formelptLTL (past-time Linear Temporal Logic)
National audienceCette communication pr´esente le champ diffusé par unesurface de mer rugueuse ca... more National audienceCette communication pr´esente le champ diffusé par unesurface de mer rugueuse calculé par l’approximation de l’optiquephysique (OP). De plus, pour tenir compte de l’effet de conduitau-dessus de la surface de mer, l’indice de réfraction n’est pasconsidéré comme constant en fonction de la hauteur mais suitune loi affine. Ainsi, pour résoudre conjointement le problème dediffraction et de propagation, tout d’abord le champ est propagéà l’aide de la fonction de Green associée à l’indice de réfraction,puis l’OP est itérée pour calculer la contribution du champdiffracté associé à chacun des rebonds. L’approche est alorsvalidée par une méthode de référence basée sur la méthode desmoments. De plus, avec l’OP, le coefficient de diffusion cohérentest calculé analytiquement, permettant ainsi de généraliser lecoefficient de réflexion d’Ament à n rebonds. Ce coefficient estcouramment appliqué dans une méthode de type “ParabolicWaveEquation (PWE)” et résolue par un schéma de type ...
HAL (Le Centre pour la Communication Scientifique Directe), Jun 12, 2015
International audienceIn civil engineering, ground penetrating radar is widely used for road pave... more International audienceIn civil engineering, ground penetrating radar is widely used for road pavement surveys. The layer thickness is deduced from both the time delays of the backscattered echoes and the permittivity of the layers. In this paper, the influence of the interface roughness is studied. A modified ESPRIT algorithm is proposed for estimating the time delay, the interface roughness and the permittivity of layers from the received echoes. The algorithm is tested on simulated data obtained from the propagation inside layer expansion (PILE) method. Numerical examples are provided to demonstrate the performance of the algorithm
Cet article presente une methode haute frequence, basee sur l’approximation de l’Optique Physique... more Cet article presente une methode haute frequence, basee sur l’approximation de l’Optique Physique (OP), pour evaluer les courants sur une surface de mer rugueuse parfaitement conductrice dans le domaine Radar des microondes. Ainsi, a partir de la connaissance de la fonction de Green du conduit (milieu stratifie decrit par un modele lineaire du profil d’indice de refraction au carre) present au-dessus de la mer, ces courants sont rayonnes a l’aide du principe d’Huygens pour calculer le champ diffuse dans le conduit. A cause du phenomene de refraction, ce champ va produire un courant sur la surface (second rebond) qui est a nouveau evalue par l’OP. Ce processus est ainsi reitere. De plus, cette methode sera validee avec une methode rigoureuse basee sur la methode des moments et acceleree par la Forward-Backward.
2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 2021
In this paper, we study the electromagnetic scattering by an object buried inside a layer with tw... more In this paper, we study the electromagnetic scattering by an object buried inside a layer with two rough interfaces. We construct a rigorous mathematical model by using the integral equations in the frequency domain and discretize these equations by the method of moments. To reduce the complexity of the inversion of the resulting impedance matrix, we derive a rapid method based on the Propagation-Inside-Layer Expansion (PILE) algorithm, which has already proven its efficiency.
This paper studies the coherent scattering from random rough layers, made up of two uncorrelated ... more This paper studies the coherent scattering from random rough layers, made up of two uncorrelated random rough surfaces. An analytical asymptotic model, based on the scalar Kirchhoff-tangent plane approximation, is proposed. The results are compared with a rigorous electromagnetic method called PILE (Propagation-Inside-Layer-Expansion) for studying the validity of the model. This approach is applied to road survey by GPR at nadir.
This paper presents new results of a simulation of radar backscatter from oil slick areas on a re... more This paper presents new results of a simulation of radar backscatter from oil slick areas on a real three-dimensional sea surface, based on a physical hydrodynamic model of surface wave damping in the presence of oil films, the local equilibrium model (MLB). To solve this problem, the modelling was carried out by using the first-order small-slope approximation (SSA1) model. It presents the advantage of having a very good compromise between rapidity and accuracy of the calculation. The choice of the model is justified by solving the two-dimensional problem with several asymptotic methods and further comparing the results with a rigorous numerical method, based on the Method of Moments (MoM). Two approaches called “thin-layer” (TL) and “classical” were used to deal with the double layer (air/oil/sea) problem. The TL approach assumes that this double-layer problem can be seen locally as a Fabry–Pérot interferometer, which implies that the Kirchhoff-tangent plane approximation (KA) is v...
This paper addresses the subject of electromagnetic wave scattering in layered media, thus coveri... more This paper addresses the subject of electromagnetic wave scattering in layered media, thus covering the recent progress achieved with different approaches. Existing theories and models are analyzed, classified, and summarized on the basis of their characteristics. Emphasis is placed on both theoretical and practical application. Finally, patterns and trends in the current literature are identified and critically discussed.
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Papers by Nicolas Pinel