Localization of Buried Objects Using Reflected Wide-Band Underwater Acoustic Signals

This chapter deals with the localization of wide-band underwater acoustic sources. A combination of high resolution methods with scattering acoustic model are proposed. The bearing and the range sources at each sensor are expressed as a function to those at the first sensor. We present the noneigendecomposition methods fixed-point algorithm, projection approximation subspace tracking (PAST) algorithm, PAST with deflation (PASTD) algorithm and orthogonal PAST (OPAST) algorithm to track the signal subspace to compute leading eigenvectors. The proposed algorithms are faster than singular value decomposition (SVD) for MUSIC. The spatial smoothing operator is used to decorrelate the received signals and to estimate the coherent signal subspace. The performance of the different methods are evaluated by both computer simulations and experimental and data recorded during underwater acoustic experiments

Contrasting space-time schemes for MIMO FSO systems with non-coherent modulation

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Localization of Buried Objects in Sediment Using High Resolution Array Processing Methods

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Spectral-Spatial Method for Hyperspectral Image classification in Noisy Environment

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Noise reduction on mammographic phantom images

A noise reduction scheme on digitized mammographic phantom images is presented. This algorithm is based on a direct contrast modification method using an optimal function which is obtained by means of the mean squared error as a criterion. Computer simulated images containing objects similar to those observed in the phantom are built to evaluate the performance of the algorithm. Noise reduction results obtained on both simulated and real phantom images show that the developed method may be considered as a good pre-processing step from the point of view of automating phantom film evaluation by means of image processing

Traitement multidimensionnel du signal par décomposition tensorielle

- La modélisation multidimensionnelle du signal a été récemment adoptée moyennant 1' utilisation de nouveaux outils d'algèbre multilinéaire. Cet article présente tout d'abord la décomposition tensorielle de Tucker3 appelée aussi approximation de rang-(R1,..., RN) inférieur d' un tenseur, puis montre comment cet outil mathématique permet de développer un filtrage linéaire multdimensionnel. Une étude sur l'efficacité du filtrage est proposée pour le cas particulier du débruitage d'une image en couleur

Méthode haute résolution large bande pour la localisation d'objets enfouis

Cette étude traite le problème de la localisation d'objets enfouis en utilisant une source acoustique. Nous proposons une nouvelle méthode qui incorpore la solution exacte du champ réfléchi dans la méthode MUSIC et qui utilise le lissage fréquentiel pour décorréler les signaux afin d'estimer les directions d'arrivée des signaux réfléchis et les distances obliques entre l'antenne et les objets à localiser. Les performances de la méthode proposée sont validées sur des données expérimentales enregistrées durant des expériences d'acoustique sous-marine

PAM- and CAP-Based Transmission Schemes for Visible-Light Communications

Visible light communications (VLCs) have received extensive attention in the research community thanks to their advantages of high bandwidth, low cost, robustness to electromagnetic interference, operation in an unregulated spectrum, and high degree of spatial confinement in indoor scenarios. One of the main limitations for high data-rate transmission in VLC systems is the limited modulation bandwidth of commercial light emitting diodes. To circumvent this limitation, spectrally efficient modulation schemes should be used. Optical orthogonal frequency-division multiplexing (O-OFDM)-based schemes have become very popular and several proofs of concept have shown their ability to attain over gigabits per second transmission rates. We consider here the use of pulse amplitude modulation and carrier-less amplitude and phase modulation schemes together with frequency-domain equalization (FDE) at the receiver as interesting alternatives to O-OFDM. We show the advantages of the former schemes in terms of the peak-to-average-power ratio, and demonstrate through numerical results the merits of FDE-based signaling in attaining high data rates

Multispectral texture characterization: application to computer aided diagnosis on prostatic tissue images

International audienceVarious approaches have been proposed in the literature for texture characterization of images. Some of them are based on statistical properties, others on fractal measures and some more on multi-resolution analysis. Basically, these approaches have been applied on mono-band images. However, most of them have been extended by including the additional information between spectral bands to deal with multi-band texture images. In this article, we investigate the problem of texture characterization for multi-band images. Therefore, we aim to add spectral information to classical texture analysis methods that only treat gray-level spatial variations. To achieve this goal, we propose a spatial and spectral gray level dependence method (SSGLDM) in order to extend the concept of gray level co-occurrence matrix (GLCM) by assuming the presence of texture joint information between spectral bands. Thus, we propose new multi-dimensional functions for estimating the second-order joint conditional probability density of spectral vectors. Theses functions can be represented in structure form which can help us to compute the occurrences while keeping the corresponding components of spectral vectors. In addition, new texture features measurements related to (SSGLDM) which define the multi-spectral image properties are proposed. Extensive experiments have been carried out on 624 textured multi-spectral images for use in prostate cancer diagnosis and quantitative results showed the efficiency of this method compared to the GLCM. The results indicate a significant improvement in terms of global accuracy rate. Thus, the proposed approach can provide clinically useful information for discriminating pathological tissue from healthy tissue