Observers Design for a Class of Lipschitz Discrete-Time Systems with Time-Delay

The observer design problem for nonlinear time-delay systems becomes more and more a subject of research in constant evolution Germani et al. (2002), Germani & Pepe (2004), Aggoune et al. (1999), Raff & Allgöwer (2006), Trinh et al. (2004), Xu et al. (2004), Zemouche et al. (2006), Zemouche et al. (2007). Indeed, time-delay is frequently encountered in various practical systems, such as chemical engineering systems, neural networks and population dynamic model. One of the recent application of time-delay is the synchronization and information recovery in chaotic communication systems Cherrier et al. (2005). In fact, the time-delay is added in a suitable way to the chaotic system in the goal to increase the complexity of the chaotic behavior and then to enhance the security of communication systems. On the other hand, contrary to nonlinear continuous-time systems, little attention has been paid toward discrete-time nonlinear systems with time-delay. We refer the readers to the few existing references Lu & Ho (2004a) and Lu & Ho (2004b), where the authors investigated the problem of robust H∞ observer design for a class of Lipschitz time-delay systems with uncertain parameters in the discrete-time case. Their method show the stability of the state of the system and the estimation error simultaneously. This chapter deals with observer design for a class of Lipschitz nonlinear discrete-time systems with time-delay. The main result lies in the use of a new structure of the proposed observer inspired from Fan & Arcak (2003). Using a Lyapunov-Krasovskii functional, a new nonrestrictive synthesis condition is obtained. This condition, expressed in term of LMI, contains more degree of freedom than those proposed by the approaches available in literature. Indeed, these last use a simple Luenberger observer which can be derived from the general form of the observer proposed in this paper by neglecting some observer gains. An extension of the presented result to H∞ performance analysis is given in the goal to take into account the noise which affects the considered system. A more general LMI is established. The last section is devoted to systems with differentiable nonlinearities. In this case, based on the use of the Differential Mean Value Theorem (DMVT), less restrictive synthesis conditions are proposed

Knowledge of risk factors, beliefs and practices of female healthcare professionals towards breast cancer, Morocco

le doctors were the only professional group that had satisfactory knowledge of risk factors while the nurses had an unsatisfactory knowledge with a mean score of 43%. A half of participants believed that that herbal therapy can cure breast cancer. 75% practice breast self-examination once a month and only 15% have ever had a mammogram. Age, profession and beliefs were not significantly associated with rate of BSE in this study; however this rate is influenced by knowledge of breast cancer risk factors. CONCLUSION: Results from this study suggest the need for continuing medical education programs aimed at improving knowledge of breast cancer among the nurses

Primary osteosarcoma of the breast: case report

Mammary sarcomas are very uncommon and make up less than 1% of all primary breast malignancies

Triple malignancy in a single patient including a cervical carcinoma, a basal cell carcinoma of the skin and a neuroendocrine carcinoma from an unknown primary site: A case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>The occurrence of multiple primary cancers is rare. Only a few cases and patient reviews of an association of triple malignancy have been reported.</p> <p>Case presentation</p> <p>We report here a case of a 78-year-old Moroccan woman presenting initially with a synchronous double malignancy, the first in her cervix and the second in her skin. Our patient was treated with radiation therapy for both tumors and remained in good control for 17 years, when she developed a metastatic disease from a neuroendocrine carcinoma of an unknown primary site.</p> <p>Conclusions</p> <p>Although the association of multiple primary cancers can be considered a rare occurrence, improving survival in cancer patients has made this situation more frequent.</p

Contribution a l'estimation de l'etat et des parametres des systemes singuliers. Application au diagnostic

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 81239 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Observer synthesis method for Lipschitz nonlinear discrete-time systems with time-delay: An LMI approach

International audienceIn this paper, we address the problem of observer design for a class of Lipschitz nonlinear discrete-time systems with time-delay. The main contribution lies in the use of a new structure of the proposed observer with a novel Lyapunov-Krasovskii functional. Thanks to these designs, new nonrestrictive synthesis conditions, expressed in terms of linear matrix inequalities (LMIs), are obtained. Indeed, the obtained LMIs contain more degree of freedom than those established by the approaches available in the literature which consider a simple Luenberger observer with a simple Lyapunov function for the stability analysis. An extension of the presented result to H-inf performance analysis is given in order to take into account the noise (if it exists) affecting the considered system

Sur l'observation d'une classe de systèmes nonlinéaires

En raison du fait que des nombreux processus et systèmes du monde réel peuvent être modélisés comme des systèmes commutés ou des systèmes multi-modèles, la synthèse d'observateurs pour ce type de systèmes a suscité un intérêt croissant ces dernières décennies. Une deuxième raison qui justifie cet intérêt vient du fait que les observateurs d état peuvent être appliqués au cryptage des données pour les systèmes de télécommunication. Dans cette thèse, nous proposons quelques méthodes de synthèse d observateurs d état pour des systèmes commutés et des systèmes multi-modèles. En utilisant de nouvelles fonctions de Lyapunov, ces approches permettent de réduire le conservatisme des approches actuellement disponibles dans la littérature. Les résultats obtenus ont été vérifiés sur des exemples de la litterature.Due to the fact that many processes and systems in real world applications can be modeled as switched systems or multi-model systems, the synthesis of observers for these classes of systems has received a growing interest in the last decades. A second reason that justifies the interest for this research area comes from the fact that it can be applied to data encryption/decryption for telecommunication applications. In this thesis, we propose some methods for synthesizing state observers for switched systems and multi-model systems. By using new Lyapunov functions, these methods reduce the conservatism of the current approaches available in the literature. The results were verified on examples from literature.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Observation des systèmes non-linéaire à entrées inconnues (Application à la pile à combustible de type PEM)

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF