Robust mixed H-2/H∞ control for a class of nonlinear stochastic systems

The problem of mixed H2/H∞ control is considered for a class of uncertain discrete-time nonlinear stochastic systems. The nonlinearities are described by statistical means of the stochastic variables and the uncertainties are represented by deterministic norm-bounded parameter perturbations. The mixed H2/H∞ control problem is formulated in terms of the notion of exponentially mean-square quadratic stability and the characterisations of both the H2 control performance and the H∞ robustness performance. A new technique is developed to deal with the matrix trace terms arising from the stochastic nonlinearities and the well-known S-procedure is adopted to handle the deterministic uncertainities. A unified framework is established to solve the addressed mixed H2/H∞ control problem using a linear matrix inequality approach. Within such a framework, two additional optimisation problems are discussed, one is to optimise the H∞ robustness performance, and the other is to optimise the H2 control performance. An illustrative example is provided to demonstrate the effectiveness of the proposed method.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant GR/S27658/01, the Nuffield Foundation of the UK under Grant NAL/00630/G and the Alexander von Humboldt Foundation of Germany, the National Natural Science Foundation of China under Grant 60474049 and the Fujian provincial Natural Science Foundation of China under Grant A0410012

Gestion des déchets hospitaliers au Maroc. Cas du CHU de Rabat-Salé et de l’Hôpital Militaire Moulay Ismail de Meknès.

Le secteur des déchets, et en particulier celui des déchets hospitaliers représente un fardeau de plus en plus encombrant: près de 8000 tonnes de déchets solides hospitaliers sont produits chaque année au Maroc(les déchets liquides étant difficilement quantifiables). Ces déchets, qui se distinguent en déchets médicaux proprement dit, et en déchets ménagers et assimilables, se répartissent entre deux grands types d’hôpitaux: les centres hospitaliers universitaires et les hôpitaux périphériques. Dans notre étude, nous avons pris l’exemple du CHU de Rabat-Salé où la gestion des déchets hospitaliers est à l’ordre du jour; A son niveau, il existe une production quotidienne de 9,75 pour une capacité litière de 3250 lits; Mais à fin de mieux cerner le problème de la gestion des déchets au CHU, nous avons choisi l’Hôpital d’Enfant de Rabat où l’ensemble des services génères une production de déchets d’environ 3594 kg/jour. En parallèle, nous avons choisi l’Hôpital Militaire Moulay Ismail de Meknès; à son niveau, l’estimation de la quantité de déchets produits chaque jour, est de 1075kg. D’autre part, grâce à une étude de proximité, nous avons pu constater l’ampleur de la problématique des déchets hospitaliers, analysons ces différents problèmes et nous proposons dans la mesure de nos moyens quelques solutions. Au niveau de certains hôpitaux, la prise de conscience de la problématique des déchets par l’ensemble des acteurs concernes, a permis de rechercher une solution pour l’amélioration de ce secteur; Celle-ci repose sur la bonne maîtrise tout le long de la chaîne d’élimination: tri, collecte, entreposage, transport et traitement. Enfin, la 28-00 de loi, a permis de combler le vide juridique qui se faisait sentir dans ce domaine

Global input constrained adaptive lambda-tracking with application to a nonlinear distributed parameter exothermic chemical reaction models in tubular reactor

We consider input constrained adaptive output feedback control for exothermic chemical tubular reactor with axial dispersion. we use a non linear distributed parameter model with boundary control for both the evolution of the temperature and concentration. Our objective is the set point control of the output i.e, the temperature of the reaction. Practical consideration lead us to work in the presence of input constraints. we apply a λ-tracking controller, we show that for all initial temperature and under a simple feasibility assumptions that the tracking error tends asymptotically to a ball centred at the reference temperature and of arbitrary prescribed radius

Adaptive local tracking of a temperature profile in tubular reactor with partial measurements

In this work, a local constrained adaptive output feedback is presented for a class of exothermic tubular reactors models described by a nonlinear partial differential equations. The considered output is the measured temperature in a fixed zone of the reactor to regulate the temperature throughout the reactor to a ball with radius λ (arbitrarily small) centered at the fixed temperature profile. For a given measurement zone with length given in terms of the desired profile and λ and for initial temperature in a fixed domain, it is shown that the tracking error through the reactor tends asymptotically to a ball of arbitrary prescribed radius λ > 0, centered at the given temperature profile. Numerical simulations have been performed to illustrate the performance of the proposed approach

Constrained Global Adaptive Controller for a Plug flow Tubular Reactor with Partial Temperature Measurements

In this work, a global constrained adaptive output feedback is presented for a class of plug-flow tubular reactors models described by non-linear partial differential equations. The output of the system is the measured temperature in a fixed zone of the reactor. It is then used to regulate the temperature throughout the reactor to a ball with radius λ (arbitrarily small) centred at the fixed temperature profile

Global Adaptive λ Tracking of a Temperature Profile in Tubular Reactor

This paper deals with the control design for a class of nonlinear distributed parameter systems, i.e. convection-diffusion-reaction systems, encountered under the form of non-isothermal tubular reactors in chemical engineering applications. More specifically the design concentrates on the boundary control of the temperature profile in an exothermic chemical reactor under input constraints. Our objective is to analyze the global stability of the closed-loop system by considering a simple control structure, i.e. an adaptive λ-tracking controller. It is shown that for all initial temperature and under simple feasibility assumptions, the tracking error tends asymptotically to a ball of arbitrary prescribed radius λ> 0, centered at the given temperature profile