Showing papers by "University of Lorraine published in 2005"

Some New Techniques in Design and Analysis of Exact (Exponential) Algorithms

Abstract: This survey concerns techniques in design and analysis of algo- rithms that can be used to solve NP hard problems faster than ex- haustive search algorithms (but still in exponential time). We discuss several of such techniques: Measure & Conquer, Exponential Lower Bounds, Bounded Tree-width, and Memorization. We also consider some extensions of the mentioned techniques to parameterized algo- rithms.

Evaluation of the antimicrobial effects of several isothiocyanates on Helicobacter pylori.

Abstract: The antibacterial activity of sulforaphane [4-(methylsulfinyl)butyl isothiocyanate] has been previously described. We have analysed the activities of 12 isothiocyanates (ITC) including sulphoraphane on 25 strains of Helicobacter pylori using an agar dilution assay. In addition, bactericidal effects against H. pylori were determined for the 6 most active ITCs, both directly and against intracellular bacteria in cultured human epithelial (HEp-2) cells. The MIC90 values for these ITCs ranged between 4 and 32 microg/mL and four of the most potent compounds exhibited bactericidal activity against both extra- and intracellular bacteria. Overall, our data indicate that ITCs have a potent antibacterial effect against H. pylori and these naturally occurring phytochemicals might have potential as novel therapeutic agents for H. pylori eradication.

Fuel Cell and Supercapacitors for Automotive Hybrid Electrical System

Abstract: The design and testing of a purely supercapacitor energy storage system for the power conditioning of automotive system having a PEM fuel cell as main source is presented. The innovative control strategy is that fuel cell is simply operating in almost steady state conditions in order to lessen the mechanical stresses of fuel cell and to insure a good synchronization between fuel flow and fuel cell current. Supercapacitors are functioning during absence of energy from fuel cell, transient energy delivery or transient energy recovery. The system utilizes a supercapacitive storage device, composed of six components (3,500 F) associated in series. This device is connected to a 42 V dc bus by a 2-quadrant dc/dc converter, and fuel cell is connected to the dc bus by a boost converter. The system structure is realized by analogical current loops and digital control (dSPACE) for voltage loops and estimation algorithms. Experimental results with a 500 W PEM fuel cell point out the slow dynamics of fuel cell because of thermodynamic and mechanical operation, and also substantiate that the supercapacitors can improve dynamics and power conditioning for automotive electrical system.

Robust analysis and synthesis of linear polytopic discrete-time periodic systems via LMIs

Abstract: A particular class of uncertain linear discrete-time periodic systems is considered. The problem of robust stabilization of real polytopic linear discrete-time periodic systems via a periodic state-feedback law is tackled here. Using additional slack variables and the periodic Lyapunov lemma, an extended sufficient condition of robust stabilization is proposed. Based on periodic parameter-dependent Lyapunov functions, this last condition is shown to be always less conservative than the more classic one based on the quadratic stability framework. This is illustrated on numerical examples from the literature.

La représentation de la Responsabilité Sociale des Entreprises : une confrontation entre les approches théoriques et les visions managériales

Abstract: Resume : Le theme de la Responsabilite Sociale de l’entreprise (RSE) est a la mode. Le succes de cette notion aupres des dirigeants d'entreprise traduit la volonte de mieux maitriser les contraintes societales et de favoriser un developpement commercial et une performance economique durables. Au-dela des finalites affichees, les preoccupations et les pratiques reelles des entreprises correspondent-elles veritablement aux valeurs vehiculees par le concept de la RSE ? Nous etudions dans cet article la diffusion des principes de la RSE au sein des entreprises a travers leurs discours. Il s’agit de reperer les elements de convergence et de divergence entre les approches theoriques de la RSE avec les preoccupations manifestees par les entreprises en matiere de responsabilite sociale. Nous abordons dans une premiere partie la variete des thematiques valorisees dans les travaux academiques. Dans un deuxieme temps, nous analysons les preoccupations affichees par les equipes dirigeantes en matiere de RSE, telles qu'elles sont communiquees aux diverses parties prenantes de l'entreprise. Sur la base d’un echantillon d’entreprises europeennes, nous etudions la rhetorique mise en œuvre et les representations que le discours de la RSE vehicule. Nous confrontons, dans une troisieme partie, les preoccupations theoriques et les "postures" manageriales en matiere de RSE.

Control of the cylinder wake in the laminar regime by Trust-Region methods and POD Reduced Order Models

Abstract: In this paper we investigate the optimal control approach for the active control of the circular cylinder wake flow considered in the laminar regime (Re = 200). The objective is the mean drag minimization of the wake where the control function is the time harmonic angular velocity of the rotating cylinder. When the Navier-Stokes equations are used as state equation, the discretization of the optimality system leads to large scale discretized optimization problems that represent a tremendous computational task. In order to reduce the number of state variables during the optimization process, a Proper Orthogonal Decomposition (POD) Reduced Order Model (ROM) is then derived to be used as state equation. Since the range of validity of the POD ROM is generally limited to the vicinity of the design parameters in the control parameter space, we propose to use the Trust-Region Proper Orthogonal Decomposition (TRPOD) approach, originally introduced by Fahl (2000), to update the reduced order models during the optimization process. Benefiting from the trust-region philosophy, rigorous convergence results guarantee that the iterates produced by the TRPOD algorithm will converge to the solution of the original optimization problem defined with a high a fidelity model. A lot of computational work is indeed saved because the optimization process is now based only on low-fidelity models. When the TRPOD is applied to the wake flow configuration, this approach leads to a relative mean drag reduction of 30% for reduced numerical costs.

Playing Cards with Hintikka: An Introduction to Dynamic Epistemic Logic

Abstract: This contribution is a gentle introduction to so-called dynamic epistemic logics, that can describe how agents change their knowledge and beliefs. We start with a concise introduction to epistemic logic, through the example of one, two and finally three players holding cards; and, mainly for the purpose of motivating the dynamics, we also very summarily introduce the concepts of general and common knowledge. We then pay ample attention to the logic of public announcements, wherein agents change their knowledge as the result of, indeed, public announcements. One crucial topic in that setting is that of unsuccessful updates: formulas that become false when announced. The Moore-sentences that were already extensively discussed at the conception of epistemic logic in [15] give rise to such unsuccessful updates. After that, we present a few examples of more complex epistemic updates. Our closing observations are on recent developments that link the ‘standard’ topic of (theory) belief revision [1] to the dynamic epistemic logics introduced here.

A Fast Algorithm for the Self-Organizing Map on Dissimilarity Data

Abstract: In this paper, we propose a new implementation of an adaptation of Kohonen's Self-Organizing Map (SOM) to dissimilarity data. We propose first a modified algorithm that allows an important reduction of the theoretical cost. Moreover, we introduce implementation techniques that allow to obtain very short running time. We illustrate the obtained method on simulated and real world data.

On a wide class of nonlinear models for non-Newtonian fluids with mixed boundary conditions in thin domains

Abstract: The behaviour of Newtonian and non-Newtonian flows through a thin three-dimensional domain are widely studied in the literature. Usually, authors deal with special models related to particular concrete fluids. In this work, our aim is to present a general model, governing the behaviour of a large class of Newtonian and non-Newtonian fluids. Moreover, we deal with mixed boundary conditions, which are not often studied in the literature related to flows in thin domains. We consider a nonlinear model of a flow in a thin three-dimensional domain, and we study its behaviour when the thickness in one direction tends to zero. At the limit, we obtain a quasilinear two-dimensional problem for the pressure, a nonlinear Reynolds's law for the velocity and a nonlinear Darcy's law for the averaged velocity. Finally, we check that our results hold for a large class of non-Newtonian fluids by producing concrete examples.

Coupling the dynamics of statistically distributed and excess dislocations

Abstract: Modeling the self-organization and collective behavior of dislocation ensembles is of primary concern in this work. Two dislocation species are considered: excess dislocations seen as a manifestation of lattice incompatibility, and statistically distributed dislocations, which induce compatible deformation. Conventional slip-based crystal plasticity is used to model the behavior and dynamics of the latter, while Field Dislocation Mechanics is employed to account for the former. Coupling the dynamics of both species proceeds along two reciprocal ways: spatial gradients in slip produced by mobile statistical dislocations leads to nucleation of excess dislocations, while excess dislocations contribute to forest hardening. Illustration is given to the evolution of mobile and excess dislocation density. Dislocation arrangements resulting from the model are presented.

Espaces politiques au féminin

Abstract: En faisant actuellement leur entree dans les sciences de l’information et de la communication (SIC), les etudes sur le genre prennent en charge des preoccupations presentes ailleurs depuis plus longtemps, notamment en histoire, en sociologie, en ethnologie, en anthropologie (voir MEI, 2004 ; Reseaux, 2003). S’appuyant sur le constat que faisaient Thierry Lancien et al. (2001 : 49), Isabelle Gavillet – qui, dans ce dossier mene une reflexion generale sur le sujet – note qu’il y a quelques anne...

Innovation in engineering education: a French sample of design and continuous updating of an engineering school to industrial needs

Abstract: The ENSGSI (National School of Industrial Engineering) was founded in 1993 and drives this new approach to training engineers. Cooperation with the economic environment is organised around three actions: accompanying industrial change within regional SMEs; proposing actions to accompany the sparking of innovation in major industries as well as in service sectors such as health; structuring the management of complex local government projects. This paper will present how the evolution in industrial and economic demand regarding the question of innovation, as well as the consideration of this in the orientation of a French laboratory's research projects, contributed to reducing the gap between corporate requirements for a new type of engineer and the capacity of engineering schools to meet this demand. We will present the methods used both to design the school and to build our teaching referential which ensures a process of permanent adjustment to market needs.

Optimization of the design for a switched reluctance drive controlled by trapezoidal shaped currents

Abstract: This papers deals with an original way to optimize the pre-designing of a switched reluctance motor (SRM). The analytic equations are treated to make the complete design depend only on two parameters. Particular attention is paid to high rotational speeds and the hypotheses they induce on the design. The hypothesis of a current control is assumed and the methodology tackles the design problem through the angle of the power electronics constraints. The specific problem set by the trapezoidal current shape is highlighted, as much as the direct constraints induced on the motor shape design. Mechanical and thermal limitations, modeled in function of the main material characteristics are deterministically taken into account. An optimization is finally performed, reducing the losses of the motor in terms of the mere lasting parameter.

L'« invention de la Lorraine industrielle »: Note sur un processus en cours

Abstract: ResumeEntrepris depuis un quart de siecle, le demantelement de l’industrie lourde lorraine (mines et siderurgie) touche a sa fin. A partir de la comparaison entre le dernier evenement en date, la fermeture spectaculaire de la derniere mine de charbon, et la mise en scene, une decennie plus tot, de la derniere coulee d’une usine de la Lorraine siderurgique, l’auteur s’interroge sur les finalites patrimoniales de telles celebrations. Presentant quelques moments du traitement culturel – patrimonial, memoriel… – de la crise industrielle lorraine, depuis les symptomes photographiques d’une memoire empechee jusqu’au musee tres « controle » en passant par la monumentalisation controversee de restes industriels, il met l’accent sur la lutte des representations qui se noue autour de la construction de la « Lorraine industrielle » en objet-frontiere patrimonial. Cet article souhaite ainsi contribuer a une anthropologie politique de l’institution de la memoire.

Dissociative simple ionization of two active electron diatomic systems by fast electron impact

Abstract: The dissociative (e, 2e) ionization of diatomic hydrogen and lithium by fast electrons is studied theoretically as a vertical transition from the lowest vibrational and rotational level of the fundamental electronic state 1 � + of H2 (and Li2) to the first dissociative 2 � u state of H2 + (and Li2 + ). After verification of the perturbative procedure in the non-dissociative case, for which experimental and theoretical results exist, the variation of the multiply differential cross section of the dissociative ionization is studied in a variety of situations to show the particularities of this process and motivate actually realizable complete experiments, which can detect the scattered and ejected electrons in coincidence with the bare detached nucleus. Our results show that the dynamically well understood behaviour in the case of simple (e, 2e) ionization breaks down in the dissociative case, because of the increasing influence of the electron–electron correlation of the two target electrons.

Gérer les risques à l'hôpital : de l'inquiétude des acteurs à la méthode

Abstract: Si l'hopital a de tous temps gerer les risques, ils relevaient du strict domaine medical. Aujourd'hui, les medecins doivent rendre des compte et la fatalite n'est plus une explication suffisante des accidents. Le risque est entre en gestion. Or, l'hopital est demuni et paralyse face au risque. L'objet de cette these est de montrer que la gestion des risques a l'hopital ne peut se contenter de l'approche empirique de laquelle elle releve actuellement et qu'un retour aux sources theoriques s'impose. Apres l'echec relatif des demarches qualite a l'hopital, nous montrerons que la gestion des risques peut etre perenne si elle repond aux maux de l'hopital au dela du risque. Elle peut etre de ce point de vue un levier legitime du changement. Apres avoir inventorie les differents modeles de gestion des risques, nous proposons un modele conceptuel d'apprehension du risque reposant sur le triptyque dysfonctionnement, alea et erreur puis, dans un second temps a l'issue d'une phase d'experimentation menee au sein d'un CHU, une methode generale de gestion des risques a l'hopital

Les enjeux culturels de la société de l'information

Abstract: Comment penser la diffusion des technologies de l'information ? Nous souhaitons contribuer a une reflexion qui replace les evolutions technologiques dans leur environnement social et culturel. La societe de l'information se developpe dans un contexte historique qui distingue notre societe d'autres qui l'ont precedee. La hierarchisation sociale s'accompagne d'une place importante accordee a la fois aux appartenances sociales mais aussi a la definition d'un individu autonome. Nous montrons comment Internet se combine avec chacun de ces enjeux. Le succes de certaines technologies et de certains sites web plonge ses racines dans leur capacite a permettre aux individus de satisfaire aux differentes facettes de l'identite des individus telles qu'elles s'imposent dans les societes occidentales contemporaines.

Monitoring mineral surface phenomena by infrared reflection spectroscopy

Abstract: Determination of the mineral surface composition and structure at molecular and atomic levels and understanding adsorption mechanisms and kinetics are crucial to perform efficient separation processes for mineral beneficiation. This understanding is a fundamental requirement to make possible the prediction and control of the macroscopic surface properties that govern the efficiency of separation technologies. The developed infrared external reflection technique has a unique ability to study interface phenomena at a molecular level on heterogeneous substrates. The variety, precision and reliability of information about interface phenomena delivered by this technique are superior to other single techniques. The experiments are fast and non-destructive. High sensitivity (part of monolayer), insitu collected information in a multiphase system even in the region of a strong absorption of substrate, makes this technique a very valuable experimental tool. The complexity of the recorded reflection spectra, their sensitivity to any variations of the optical properties of all bulk and surface components and their spatial distribution in the system under investigation, are in fact the major strength of the technique. In this paper a few examples of application of this multidiagnostic technique for monitoring surface modifications of sulphide and semisoluble minerals for selective flotation are overviewed in detail.

Experimental Proof of the Existence of a Bifurcation Process During the undrained test in Clay

Abstract: Recent papers, based on a new simple incremental modelling which assumes an "isotropic" response, predicts that the trajectory followed during an undrained compression test exhibits a bifurcation process when the stress field arrives at q=M'p', where q stands for the deviatoric stress, p' for the mean stress and M' is a coefficient describing friction. This indicates a discontinuous change of solution when arriving at q=M'p'. This paper looks at experimental data on dense sample obtained at p'=constant, and it shows that the trajectory (p'=constant, v=constant) does continue to exist at and beyond the q=M'p' plane. So, this demonstrates the validity of the analysis which uses the bifurcation theory and this strengthens the proposed modelling. Indeed, this demonstrates the reality of the bifurcation process during undrained compression. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn

Information display by haptic bumps Affichage d'informations par des impulsions haptiques

Abstract: Our goal was to find haptic effects that could be used to present information to the user of a haptic pointing device. We present a study on users’ ability to discriminate between different effects presented with a PHANToM haptic pointing device. The effects we experimented with were bumps that the user could feel through the PHANToM. The direction and the amplitude of the bumps were manipulated. The results show that the direction is easy to discriminate, but the amplitude is not. Only two levels of amplitude could be reliably discriminated.

Petrophysics and Permeability in the Soultz Granite

Abstract: This study presents a multidisciplinary approach to understand and describe fracture permeability in the Soultzsous-Forets granite (Bas-Rhin, France). At Soultz, during the 1993 stimulation tests in the GPK1 well, it was shown that only a limited number of natural fractures contributed to flow whereas there are thousands of fractures embedded within the massive granite. In order to understand the past and actual flow hierarchy, a detailed comparison between petrophysics (log correlations), static (fracture apertures based on ARI raw curves) and dynamic data (hydraulic tests) is carried out. The hierarchy of flow is strongly dependant of the petrophysical properties of the rock and especially is directly linked to the intensity of the granite hydrothermal alteration. Log charts with Gamma Ray and bulk density logs are proposed to qualify the hydraulic behavior of fractures. The final objective remains the matching of structural and hydraulic models.