Autoregressive models for text independent speaker identification in noisy environments

The closed-set speaker identification problem is defined as the search within a set of persons for the speaker of a certain utterance. It is reported that the Gaussian mixture model (GMM) classifier achieves very high classification accuracies (in the range 95% - 100%) when both the training and testing utterances are recorded in sound proof studio, i.e., there is neither additive noise nor spectral distortion to the speech signals. However, in real life applications, speech is usually corrupted by noise and band-limitation. Moreover, there is a mismatch between the recording conditions of the training and testing environments. As a result, the classification accuracy of GMM-based systems deteriorates significantly. In this thesis, we propose a two-step procedure for improving the speaker identification performance under noisy environment. In the first step, we introduce a new classifier: vector autoregressive Gaussian mixture (VARGM) model. Unlike the GMM, the new classifier models correlations between successive feature vectors. We also integrate the proposed method into the framework of the universal background model (UBM). In addition, we develop the learning procedure according to the maximum likelihood (ML) criterion. Based on a thorough experimental evaluation, the proposed method achieves an improvement of 3 to 5% in the identification accuracy. In the second step, we propose a new compensation technique based on the generalized maximum likelihood (GML) decision rule. In particular, we assume a general form for the distribution of the noise-corrupted utterances, which contains two types of parameters: clean speech-related parameters and noise-related parameters. While the clean speech related parameters are estimated during the training phase, the noise related parameters are estimated from the corrupted speech in the testing phase. We applied the proposed method to utterances of 50 speakers selected from the TIMIT database, artificially corrupted by convolutive and additive noise. The signal to noise ratio (SNR) varies from 0 to 20 dB. Simulation results reveal that the proposed method achieves good robustness against variation in the SNR. For utterances corrupted by covolutive noise, the improvement in the classification accuracy ranges from 70% for SNR = 0 dB to around 4% for SNR = 10dB, compared to the standard ML decision rule. For utterances corrupted by additive noise, the improvement in the classification accuracy ranges from 1% to 10% for SNRs ranging from 0 to 20 dB. The proposed VARGM classifier is also applied to the speech emotion classification problem. In particular, we use the Berlin emotional speech database to validate the classification performance of the proposed VARGM classifier. The proposed technique provides a classification accuracy of 76% versus 71% for the hidden Markov model, 67% for the k-nearest neighbors, 55% for feed-forward neural networks. The model gives also better discrimination between high-arousal emotions (joy, anger, fear), low arousal emotions (sadness, boredom), and neutral emotions than the HMM. Another interesting application of the VARGM model is the blind equalization of multi input multiple output (MIMO) communication channels. Based on VARGM modeling of MIMO channels, we propose a four-step equalization procedure. First, the received data vectors are fitted into a VARGM model using the expectation maximization (EM) algorithm. The constructed VARGM model is then used to filter the received data. A Baysian decision rule is then applied to identify the transmitted symbols up to a permutation and phase ambiguities, which are finally resolved using a small training sequence. Moreover, we propose a fast and easily implementable model order selection technique. The new equalization algorithm is compared to the whitening method and found to provide less symbol error probability. The proposed technique is also applied to frequency-flat slow fading channels and found to provide a more accurate estimate of the channel response than that provided by the blind de-convolution exploiting channel encoding (BDCC) method and at a higher information rate

Contribution a l’étude physicochimique de l’écosystème lacustre Dayet Aoua au Maroc

L’étude consiste à la détermination de la qualité physicochimique des eaux du lac Dayet Aoua situé dans le Moyen Atlas au Maroc juste après son dernier desséchement survenu en été 2002. Les résultats d’analyse obtenus au cours de la période d’étude comprise entre février et juillet 2005, montrent que les eaux du lac sont bicarbonatées calciques et magnésiennes, dures à très dures. La dureté dépend essentiellement des ions magnésium. Les analyses des formes azotées et des orthophosphates des eaux du lac donnent des valeurs très faibles, et ne décèlent aucune sorte de pollution de type organique pouvant engendrer son eutrophisation, ce qui permet de le classeractuellement parmi les lacs oligotrophes.Mots-clés : lac, physico-chimie, pollution organique, oligotrophe

An uncommon subtype of breast carcinoma in a man: The pure mucinous carcinoma

Aim: Our purpose is to describe a new case of pure mucinous carcinoma in a man, to put emphasis on the rarity of this histologic subtype and the problems of management due to the fewer reported cases in the literature and to compare it with the female counterpart. Observation: We report the case of a 79- year-old man presenting as a nodular mass of the right breast. The clinical symptoms weren’t specific and the diagnosis was based on histological and immunohistochemical findings. Conclusion: Male breast carcinoma is rare compared to its female counterpart representing less than 2% of male breast carcinomas and 1% of all breast carcinomas. Pure mucinous carcinoma in male is an extremely rare histological subtype. It is a variety of carcinoma of the breast which is characterized by the production of an abundant extra-cellular and/or intra-cellular mucin. It has been regarded as one of the more benign forms of breast carcinomas. To our knowledge, about 30 cases of mucinous breast carcinoma in male have been reported in the English literature and only 10 cases of pure mucinous carcinoma have been described. In general, pure mucinous carcinomas have a favorable prognosis. Numerous studies have shown that breast carcinomas in male behave more aggressively compared to those in females. Further research is needed on male carcinomas as they are becoming more frequent

Evaluation des traits de vie d'une espèce endémique du Maroc (Salmo trutta macrostigma, Dumeril, 1858) dans une rivière du Moyen Atlas du Maroc: Oued Sidi Rachid

Cette étude a pour objectif la contribution à la détermination de la qualité physicochimique des eaux de l'Oued Sidi Rachid au Moyen Atlas où vit une espèce endémique du Maroc : la truite de rivière (Salmo trutta macrostigma, Duméril, 1858). L'étude des paramètres essentiels pour la vie de ce salmonidé au cours de la période comprise entre le mois de mai 2007 et le mois d'avril 2008 montre que la température, le potentiel Hydrogène (pH) et les concentrations des nitrites témoignent de la bonne qualité des eaux de l'Oued Sidi Rachid et permettent de classer ce site parmi les sites à vocation salmonicole. Les concentrations des orthophosphates sont très faibles et ne témoignent d'aucune source de pollution organique. Les concentrations des indicateurs de la dureté reflètent la nature géologique (carbonatée) de la région. Les résultats obtenus montrent bien que les eaux de l'Oued Sidi Rachid assurent à la truite de rivière un bon habitat écologique favorable à son développement et à sa reproduction.Mots clés: Qualité physicochimique, Truite de rivière, Oued Sidi Rachid, Maro

Application d'un modèle de simulation et d'analyse de sensibilité à l'évaluation d'un projet de numérisation des dossiers patients

Le présent mémoire traite de l'évaluation financière de projets d'investissement publics mutuellement exclusifs dans le domaine de la santé. Il s'agit d'un projet de numérisation des dossiers patients du centre hospitalier de l'université de Sherbrooke (CHUS). La remise en cause de certains modèles et méthodes traditionnels d'évaluation de projets d'investissements tels que l'analyse coûts-bénéfices et la VAN, nous a amené à proposer une démarche d'évaluation financière multifactorielle à l'intérieur d'une même analyse de projet. Cette démarche vise à déterminer un résultat probabiliste, ce qui offre aux gestionnaires la possibilité de prendre des décisions stratégiques optimales en matière d'investissement. Cette démarche est basée sur le modèle traditionnel de la VAN en complémentarité avec l'application des modèles des options réelles et une analyse de sensibilité du projet par la simulation Monte Carlo. La combinaison de ces différentes méthodes permet de prendre en compte d'une part, les fluctuations possibles des différentes variables qui peuvent avoir une influence considérable sur le projet et d'autre part, évaluer les possibilités d'options offertes par les projets. Le présent mémoire est divisé en trois grandes parties dont, la première partie porte sur la recension des écrits dans la littérature financière. La seconde élabore sur la méthodologie utilisée et enfin la dernière partie aborde l'analyse du projet. Concernant le projet de numérisation des dossiers patients, il s'agit d'une extension des travaux débutés par Bahadi (2006), lesquels avaient abouti à cinq scénarios dont deux étaient jugés rentables (le scénario 1 avec une VAN de 3.005.473 $et le scénario 4 avec une VAN de 88.369$ et un investissement initial de 1.080.000 $). En dépit de ces résultats, les gestionnaires avaient préféré choisir le scénario 4 en procédant à une réévaluation des flux financiers lesquels nous ont été soumis pour une analyse « post-mortem ». ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Évaluation des projets, Valeur actuelle nette, Options réelles, Simulation Monte-Carlo

Functionalized azo-based iminopyridine rhenium complexes for nonlinear optical performance

Two new TTF-pi-acceptor dyads that contain p-nitrophenyl group as acceptor and bis-(styryl)benzene system as an efficient π−conjugated bridge have been synthesized by multistep synthetic procedure and their electrochemical behavior has been studied by cyclic voltammetry (CV). The occurrence of an intramolecular charge transfer (ICT) in these molecules has been evidenced by UV–Visible electronic absorption spectroscopy and these studies were completed by DFT calculations in both gas phase and in solution. The nonlinear optical parameters obtained via SHG and THG measurements are described and indicate that these materials are valuable candidates for the construction of optoelectronic and photonic devices. The Optical Kerr Effect measurements indicate that these materials exhibit a great potential in the field of optical switchers construction, where the material\u27s photoresponse time is a crucial parameter

MESURES DE LA PAUVRETE : UNE REVUE DE LITTERATURE DE L’EXISTANT

This research paper is part of an essay in development economics, through a retrospective that traces the evolution and dynamics of the concept of poverty. Indeed, it has been much in the news since it is still a major challenge for policy makers in both rich and poor countries.Thus, the objective of this research paper is to make a state of place of all the approaches developed to approximate poverty and its determinants, while demonstrating its multidimensionality and the complementarity of the criteria of identification and measured. It is in this sense that the treatment of the subject was done through a theoretical exploitation and a synthesis of the existing in order to apprehend, to identify and subsequently to act in order to eradicate the problematic of the poverty

Pyrene bisiminopyridine ligand and its zinc complex

The synthesis of a pyrene bisiminopyridine ligand L was successfully accomplished by condensation between 1-aminopyrene and 2,6-pyridinecarboxaldehyde. The complexation of L with zinc triflate afforded a neutral metal complex formulated as [Zn(H2O)LCF3SO3)2].2Et2O. In the complex, the ligand is coordinated to zinc(II) through its three nitrogen atoms which form a distorted octahedral environment together with three oxygen atoms, two from the triflate anions and one from aqua ligand. Both compounds have been characterized using NMR, elemental analysis, mass spectrometry, electronic absorption (UV-Vis) and infrared. Luminescence properties of these compounds show an emission maxima at 412 nm, indicating a pyrene monomer emission