Egalisation de canaux de transmission à l'aide de filtres de Kalman fonctionnant en parallèle

- L'égalisation de canaux de transmission numérique par filtrage de Kalman a déjà été proposée dans la littérature comme alternative à des techniques plus classiques. Cependant, cette solution n'est valable que dans le cas où les signaux sont gaussiens ce qui n'est pas toujours le cas. Partant d'une approximation d'une fonction de densité de probabilité conditionnelle de données à l'aide d'une somme pondérée de fonctions de densité de probabilités gaussiennes, nous proposons ici une nouvelle structure d'égaliseur constituée d'un réseau de filtres de Kalman opérant en parallèle. Nous montrons l'amélioration des performances apportées par cette nouvelle structure dans le cas de canaux de transmission linéaires sévères. Nous analysons le lien entre ce nouvel égaliseur et les égaliseurs bayésiens réalisés à l'aide de réseaux de fonctions de base radiales et récemment présentés dans la littérature

The implication of ROS production on triflumuron-induced oxidative stress and genotoxicity in human colon carcinoma (HCT-116) cells

The aim of this study is to evaluate the cytotoxic and the genotoxic effects of triflumuron (TFM) on human colon carcinoma cells (HCT-116). Indeed, TFM is used to protect vegetables, fruits, and domestic animals against a large spectrum of parasites causing animal and human disorders. However, studies revealing its toxicity and its mode of action in mammalian systems remain very limited. We monitored our work with the cytotoxicity assay starting with the cell viability test, the ROS generation, the malondialdehyde (MDA) production, the DNA fragmentation, and the measurement of some antioxidant enzymes activities such as catalase, superoxide dismutase, and the glutathione S-transferase. Also, we measured the mitochondrial transmembrane potential. We showed that TFM induced a dose-dependent cell death. This decrease in cell viability was accompanied by a significant reduction in the mitochondrial membrane potential. We also have shown that TFM induced oxidative stress as revealed by the generation of reactive oxygen species, the increase of the MDA levels, and the activation of the antioxidant enzymes. Moreover, our results indicated that TFM induced DNA damage in HCT-116 cells as monitored by the comet assay. We demonstrate, for the first time, the cytotoxic and the genotoxic potentials of TFM on human cultured cells

Egalisation de canaux non linéaires par filtrage de Kalman parallèle

- Dans ce papier, l'égalisation de canaux non linéaires est considérée dans un contexte d'estimation, où l'état inconnu à estimer est une séquence finie de symboles transmis. En linéarisant la fonction canal autour des états prédits, le Réseau de Filtres de Kalman (RFK) est étendu aux cas de canaux non linéaires (RFKE) [8]. Etant donné que la validité de cette linéarisation n'est pas toujours assurée, une variante du filtrage de Kalman proposée par Julier et al. [9] et basée sur un Monte-carlo déterministe pour le calcul des espérances conditionnelles mises en jeu dans le filtre de Kalman, a pu être adaptée dans ce même but

Egalisation de canaux linéaires et non linéaires (approche bayésienne)

Dans cette thèse, nous traitons le problème d'estimation Bayésienne des symboles transmis selon une formulation d'état d'un système de communications numériques en bande de base. Grohan et Marcos ont tenu compte du caractère non gaussien du bruit d'état et ont suggéré l'utilisation de l'approximation de la ddp a posteriori d'une séquence de symboles, non gaussienne donc, par une Somme Pondérée de Gaussiennes (SPG) en se basant sur la théorie de Sorenson et Alspach. Une étude comparative des différentes réalisations de l'égaliseur par Réseau de Filtres de Kalman (RFK) en découlant est effectuée au début de cette thèse afin de réaliser un bon compromis complexité/performance. Une version simplifiée de l'égaliseur par RFK sous forme d'un Réseau de Filtres LMS est fournie afin de réduire encore plus la complexité. Ensuite, nous étendons notre structure d'égaliseur par RFK au cas de canaux linéaires non stationnaires en proposant deux nouveaux algorithmes aveugles pour l'estimation conjointe du canal et des données...This phD deals with symbol-by-symbol Bayesian estimation using a state formulation of a digital communication scheme. Grohan and Marcos take into account of the non gaussian character of the state noise probability density function (pdf) and have suggested the approximation of the a posteriori symbol sequence pdf by a Weighted Gaussian Sum (WGS), based on Sorenson and Alspach formalism for non linear and/or non gaussian filtering. A comparative study concerning the different implemenations of the NFK based equalizer so developed is done at the beginning of the dissertation, in order to achieve a tradeoff between complexity and performance. A simplified version of the NFK algorithm in the form of a Network of LMS Filters (NLMSF) is also suggested in order to reduce the complexity. To deal with linear nonstationary channels, two blind algorithms are proposed for the joint MMSE estimation of the channel coefficients and the data...ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Contribution of state modelling in efficient MAP symbol-by-symbol demodulation schemes for CPM-MIMO systems

International audienceIn [1], a state space model was derived for the demodulation of Continuous Phase Modulation (CPM) signals, based on which the demodulation problem was solved through the symbol-by-symbol Bayesian estimation built around the MAP Symbol-by-symbol Detector (MAPSD). In this paper, a new state space model considered in the augmented state composed of the symbol and the phase state is proposed and the corresponding modified MAPSD demodulation scheme is presented. The main contribution of the paper however consists in deriving optimal and suboptimal symbol-by-symbol MAP detection schemes for MIMO systems operating with CPM signals. For this, a state model description of the corresponding demodulation problem is introduced based on which two CPM-MIMO Bayesian demodulators are proposed. The first one uses a Zero Forcing (ZF) pre-processing block to separate the different CPM signals followed by a bank of MAPSD based CPM demodulators. The second demodulator consists in a joint decision feedback (DF) CPM-MIMO MAPSD detector. Simulations confirm the good performance in term of BER of both proposed structures. Particularly, high BER's performance of the partially joint CPM-MIMO-MAPSD/DF is recorded and an emphasis is made on the implementation simplicity of this new detector with no constraint on the modulation index or the alphabet size

A NEW APPROACH FOR SPARSE PHASE RETRIEVAL BASED ON SUPPORT LIFTING AND LEAST SQUARE ESTIMATION

To recover a signal x from the magnitude of a possible linear transform of it, problem known as Phase Retrieval (PR), signal sparsity property has been used to guide the uniqueness of the solution. This paper presents herein a new method for sparse phase retrieval (SPR). Based on a lifting operation, we reduce the problem of SPR to solving a linear system with regards to a vectorized version of xx T. We then use the struc-tured sparsity property of this vectorized form to interpret this operation rather as a lifting operation of the signal support. The signal support is identified iteratively using the gradient pursuit principle in conjunction with subsequent refinements aiming to control the stability of the updated solution. A simple least square estimation on the lifted support is then brought out, iteratively and if required, to determine the lifted solution; from which a rank−1 decomposition is achieved to recover the signal of interest. Simulation results confirm the efficiency of the so-called Greedy Support-Lifting Based algorithm (GSuLA) with acceptable complexity. Robustness of the algorithm is also assured for noisy measurements

Review of 100 NVQs and SVQs A report submitted to the Department for Education and Employment

SIGLEAvailable from British Library Document Supply Centre-DSC:98/29387 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Synthesis of N-Aryl and N-Heteroaryl gamma-, delta-, and epsilon-Lactams Using Deprotometalation-Iodination and N-Arylation, and Properties Thereof

International audienceXanthone, thioxanthone, fluorenone, benzophenone, 2-benzoylpyridine, dibenzofuran, and dibenzothiophene were deprotonated using a base prepared in situ from MCl2TMEDA (M = Zn or Cd; TMEDA =N,N,N,N-tetramethylethylenediamine) and lithium 2,2,6,6-tetramethylpiperidide in a 1:3 ratio, as demonstrated by subsequent iodolysis. The different aryl halides were involved as partners in the N-arylation of pyrrolidin-2-one. In the presence of copper(I) iodide and tripotassium phosphate, and using dimethyl sulfoxide as solvent, the reactions could be performed in yields ranging from 40 to 70%. Most of the products were tested for their antimicrobial, antifungal, antioxidant, and cytotoxic (MCF-7) activity