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Andrieu V.,University Claude Bernard Lyon 1 | Andrieu V.,CNRS Automation and Process Engineering Laboratory | Prieur C.,CNRS Laboratory for Analysis and Architecture of Systems | Prieur C.,CNRS GIPSA Laboratory
IEEE Transactions on Automatic Control

The problem of piecing together two control Lyapunov functions (CLFs) is addressed. The first CLF characterizes a local asymptotic controllability property toward the origin, whereas the second CLF is related to a global asymptotic controllability property with respect to a compact set. A sufficient condition is expressed to obtain an explicit solution. This sufficient condition is shown to be always satisfied for a linear second order controllable system. In a second part, it is shown how this uniting CLF problem can be used to solve the problem of piecing together two stabilizing control laws. Finally, this framework is applied on a numerical example to improve local performance of a globally stabilizing state feedback. © 2010 IEEE. Source

Perret F.,University Claude Bernard Lyon 1 | Duffour M.,University Claude Bernard Lyon 1 | Chevalier Y.,CNRS Automation and Process Engineering Laboratory | Parrot-Lopez H.,University Claude Bernard Lyon 1
European Journal of Pharmaceutics and Biopharmaceutics

Acyclovir possesses low solubility in water and in lipid bilayers, so that its dosage forms do not allow suitable drug levels at target sites following oral, local, or parenteral administration. In order to improve this lack of solubility, new cyclodextrin-based amphiphilic derivatives have been designed to form nanoparticles, allowing the efficient encapsulation of this hydrophobic antiviral agent. The present work first describes the synthesis and characterization of five new O-2,O-3 permethylated O-6 alkylthio- and perfluoroalkyl-propanethio-amphiphilic β-cyclodextrins. These derivatives have been obtained with good overall yields. The capacity of these molecules to form nanoparticles in water and to encapsulate acyclovir has then been studied. The nanoparticles prepared from the new β-cyclodextrin derivatives have been characterized by dynamic light scattering and have an average size of 120 nm for the fluorinated derivatives and 220 nm for the hydrogenated analogs. They all allowed high loading and sustained release of acyclovir. © 2012 Elsevier B.V. All rights reserved. Source

Massol-Chaudeur S.,CNRS Automation and Process Engineering Laboratory | Berthiaux H.,French National Center for Scientific Research | Dodds J.A.,French National Center for Scientific Research
Chemical Engineering Science

As increasingly commented by the literature during the last 5 years, estimating the homogeneity of a powder mixture and following powder mixing processes is not a simple task. In this paper, we present the development and statistical validation of a sampling methodology for defining the number of samples required to provide a reasonable estimation of the homogeneity attained in a laboratory scale tumbler mixer. This method is then used to follow the mixing kinetics of a dilute binary powder mixture in a hoop mixer. Special attention is paid to the statistical meaning of the values obtained and the influence of the physical characteristics such as particle size and shape. The role of the particle shape of the majority powder is particularly emphasised and it is quantitatively demonstrated that spherical particles are harder to mix and more ready to segregate than particles with irregular shapes. The different mixing mechanisms at play are identified; the practical limits of use of such tumbler mixers with pharmaceutical powders are discussed. © 2002 Elsevier Science Ltd. Source

Favache A.,Catholic University of Louvain | Dochain D.,Catholic University of Louvain | Maschke B.,CNRS Automation and Process Engineering Laboratory
Chemical Engineering Science

In this paper we propose an analytical formulation of the dynamical behaviour of complex and open physical systems which is formulated on the total thermodynamic phase space using the contact form associated with Gibbs' relation. Starting from balance equations we construct control contact systems by using the entropy function to represent the thermodynamic properties. The contact Hamiltonian function generating the dynamical behaviour has then the units of an entropy variation. We consider complex thermodynamic systems, described by compartmental systems, and we construct the associated control contact system by composing the control contact formulation of every compartment. The contact Hamiltonian functions generating the dynamical behaviour are discussed with respect to two alternative formalisms used for describing coupled sets of reversible and irreversible processes, namely the GENERIC formulation and the Matrix formulation. This analysis is then illustrated on the elementary example of a coupled mechanical and thermodynamic system. © 2010 Elsevier Ltd. Source

Hammouri H.,University of Lyon | Hammouri H.,CNRS Automation and Process Engineering Laboratory | Tmar Z.,University of Tunis | Tmar Z.,British Petroleum

The problem of designing an unknown input observer for linear systems and its application to fault detection is widely studied in the literature. For nonlinear systems, only subclasses of nonlinear systems and sufficient conditions have been stated. In this paper an unknown input observer design for state affine systems is considered. Based on the geometric approach, a necessary and sufficient condition is given for the existence of an unknown input observer. © 2009 Elsevier Ltd. All rights reserved. Source

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