An optimisation approach for stability analysis and controller synthesis of linear hyperbolic systems

International audienceIn this paper, we consider the problems of stability analysis and control synthesis for first-order hyperbolic linear Partial Differential Equations (PDEs) over a bounded interval with spatially varying coefficients. We propose Linear Matrix Inequalities (LMI) conditions for the stability and for the design of boundary and distributed control for the system. These conditions involve an infinite number of LMI to solve. Hence, we show how to overapproximate these constraints using polytopic embeddings to reduce the problem to a finite number of LMI. We show the effectiveness of the overapproximation with several examples and with the Saint-Venant equations with friction

Numerical Computation of Lyapunov Function for Hyperbolic PDE using LMI Formulation and Polytopic Embeddings

International audienceWe consider the problem of stability analysis and control synthesis for first-order hyperbolic linear PDEs over a bounded interval with spatially varying coefficients. We propose LMI-based conditions for the stability and for the design of boundary and distributed control for this class of systems. These LMI-based conditions involve an infinite number of LMI. Hence, we show how to overapproximate these constraints using polytopic embeddings to reduce the problem to a finite number of LMI. We show the effectiveness of the overapproximation with several examples

Lyapunov techniques for stabilization of switched linear systems of conservation laws

http://cdc2013.units.it/International audienceIn this paper, the exponential stability in L2 - norm is investigated for a class of switched linear systems of conservation laws. The state equations and the boundary conditions are both subject to switching. We consider the problem of synthesizing stabilizing switching controllers. By means of Lyapunov techniques, three control strategies are developed based on steepest descent selection, possibly combined with a hysteresis and a low-pass filter. Some numerical examples are considered to illustrate our approach and to show the merits of the proposed strategies

Switching rules for stabilization of linear systems of conservation laws

International audienceIn this paper, the exponential convergence in L 2-norm is analyzed for a class of switched linear systems of conservation laws. The boundary conditions are subject to switches. We investigate the problem of synthesizing stabilizing switching controllers. By means of Lyapunov techniques, three control strategies are developed based on steepest descent selection, possibly combined with a hysteresis and a low-pass filter. For the first strategy we show the global exponential stabilizability, but no result for the existence and uniqueness of trajectories can be stated. For the other ones, the problem is shown to be well posed and global exponential convergence can be obtained. Moreover, we consider the robustness issues for these switching rules in presence of measurement noise. Some numerical examples illustrate our approach and show the merits of the proposed strategies. Particularly, we have developped a model for a network of open channels, with switching controllers in the gate operations

A Knowledge-Based Approach to Augment Applications with Interaction Traces

International audienceThis paper presents a trace-based framework for assisting personalization and enrichment of end-user experience in an application. We propose a modular ontology-based architecture, to provide semantics for interaction traces, observed elements and their associated objects, and we extend existing inference services, with a declarative and generic approach, in order to reason with those interaction traces. We present the architecture of our framework and its reasoning levels, provide a proof of concept on a medical Web application, and emphasize that different kinds of actors can benefit from the supported inferences

A brief review of Agenian rhinocerotids in Western Europe

Abstract The Agenian is the earliest Neogene European Land Mammal Age. It encompasses the mammalian zones MN1 (23.03-22.7 Ma) and .0 Ma) and roughly coincides with the Aquitanian standard age. Agenian mammalian assemblages from Western Europe encompass a mixture of rhinocerotid taxa of Oligocene affinities and of Miocene newcomers, mostly recorded in France, Germany, Switzerland, and to a lesser extent, Spain. Rhinocerotidae are documented by seven species referred to five genera (Pleuroceros pleuroceros, Protaceratherium minutum, Plesiaceratherium aquitanicum, Mesaceratherium paulhiacense, Diaceratherium lemanense, D. asphaltense, and D. aginense), further attesting to a low suprageneric diversity. Their systematics, morphology, ecology, stratigraphical and geographical ranges are detailed in the present article. Occurrences and geographical ranges of all seven rhinocerotid species are illustrated on palaeogeographical maps of the circum-Mediterranean region at 23 Ma (MN1) and 21 Ma (MN2). The richest Agenian localities (Paulhiac, MN1; Laugnac, MN2) record a specific diversity similar to that of Orleanian rhinocerotid assemblages, with up to five/six associated species. All Agenian rhinocerotid species from Western Europe are endemic to the concerned region, which is consistent with the complete geographic isolation of Western Europe by earliest Miocene times. However, all five genera are documented by twin species in coeval localities of South and Central Asia, which implies (1) vicariant speciation events by latest Oligocene times and (2) the existence of intermittent pathways for terrestrial megamammals such as rhinocerotids during the concerned interval

The Cave of Fouvent, also called Abri Cuvier (Fouvent-le-Bas, Haute-Saône, France): Taphonomical analysis of a Late Pleistocene Hyena Den (OIS3)

Le gisement paléontologique de Fouvent (Fouvent-le-Bas, Haute-Saône, France) est une accumulation osseuse karstique connue depuis le début du XIXe siècle. Ce site est à l’origine de nombreuses avancées paléontologiques (reconnaissance de l’hyène fossile par Cuvier, première mention du glouton en France) et taphonomique (caractérisation du repaire de carnivore). Le présent article porte sur l’analyse de 14 977 restes osseux issus à la fois de la collection historique (fouilles de 1842) et des fouilles récentes (1989-1992). Une liste faunique de 19 taxons de grands mammifères a été établie : 11 carnivores (Crocuta crocuta spelaea, Panthera (Leo) spelaea, Ursus spelaeus, Canis lupus, Vulpes vulpes, cf. Alopex, Gulo gulo, Meles meles, Martes sp., Mustela eversmanii, Mustela sp.) et 8 ongulés (Mammuthus primigenius, Coelodonta antiquitatis, Megaloceros giganteus, Cervus elaphus, Rangifer tarandus, Equus germanicus, Bos primigenius et/ou Bison priscus). L’étude des hyènes des cavernes permet de préciser les caractères d’une population du stade isotopique 3 et de discuter de sa composition. Quant au spectre d’ongulés, son identification permet de préciser la diversité des proies de l’hyène (en termes d’espèces et d’âges individuels). Les interactions entre le prédateur et ses proies sont caractérisées grâce à l’étude de la distribution squelettique, de la fragmentation osseuse, des morphologies des restes consommés et des traces de dents. L’examen détaillé de l’ensemble des éléments taphonomiques de l’accumulation osseuse de Fouvent permet de discuter et de préciser la spécificité d’un repaire d’hyènes pléistocène.The palaeontological site of Fouvent (Fouvent-le-Bas, Haute-Saône, France) is a fissure-filling bone accumulation known from the beginning of the XIXth century. This assemblage is at the origin of palaeontological (description of fossil hyena by Cuvier, first record of French wolverine) and taphonomical advances (first carnivore den characterization). This paper presents the analysis of 14 977 bone remains from both the historical collection (1842) and recent excavations (between 1989 and 1992). A faunal list of 19 mammalian species has been identified: 11 carnivore species (Crocuta crocuta spelaea, Panthera (Leo) spelaea, Ursus spelaeus, Canis lupus, Vulpes vulpes, cf. Alopex, Gulo gulo, Meles meles, Martes sp., Mustela eversmanii, Mustela sp.) and 8 large ungulate species (Mammuthus primigenius, Coelodonta antiquitatis, Megaloceros giganteus, Cervus elaphus, Rangifer tarandus, Equus germanicus, Bos primigenius and/or Bison priscus). The analysis of cave hyenas from Fouvent allows us to precise characteristics of an OIS3 population and to discuss population structure. The study of ungulate populations allows us to describe prey diversity (in terms of species and individual age). Prey skeletal part distribution, bone fragmentation, consumption morphotypes and tooth marks are observed to point out predator-prey interactions. The detailed analysis of taphonomical aspects of Fouvent bone accumulation allows also to discuss and to give criteria about hyena den characterization grids

Paleontology in France: 200 years in the footsteps of Cuvier and Lamarck

International audienceDue to its richness in fossil localities and Fossil-Lagerstätten, France played a major role in the 18th and 19th centuries in establishing paleontology and biostratigraphy as scientific disciplines. The French naturalist and zoologist Cuvier (1769-1832) established the fields of comparative anatomy and paleontology, and proposed the concept of 'catastrophism' in geology. The naturalist Lamarck (1744-1829) is considered the founder of invertebrate paleontology and biostratigraphy and an early pioneer in the studies of evolution, developing the idea of 'transformism' and creating the word 'fossil', while his successor Blainville (1777-1850) was the first to use the word 'paleontology'. Based on this rich heritage, numerous French scientists strengthened paleontology as an important discipline during the 19th and 20th centuries. Paleontology was present at the universities of most major French cities, as documented by the rich collections in over 50 natural history museums and university collections. The most significant paleontological collection is that housed in the Muséum National d'Histoire Naturelle (MNHN) at Paris that currently hosts the largest research unit in paleontology of France with over 100 scientists, curators and technicians. The second largest collection (and the largest in terms of invertebrate fossils) is housed at the University of Lyon1, where the most important university paleontology research team is present. About 250 professional paleontologists are currently working in research units that are mostly affiliated to the Centre National de Recherche Scientifique (CNRS), in public or private museums, or in the numerous natural parcs. A significant generation change took place in the early 2000s, with the retirement of the paleontologists recruited in the 1960s and 1970s, that were often specialized in alpha-taxonomy and stratigraphy, and the arrival of a young generation of scientists that attempts to answer more 'modern' questions, such as global (climate) change, biodiversity, or evolution. This new generation of paleontologists faces modified funding schemes with project-based supporting structures in a more and more competitive environment. In the present paper we attempt to summarize the current situation of paleontology as a discipline in the very complex academic and scientific context of France. After a short overview on the history of French paleontology in the last centuries, a synopsis on institutions and funding agencies is presented briefly. The major research departments and their research themes are then described, together with the most important collections, the paleontological associations, journals, and databases, etc. Paleontological training possibilities and job opportunities, in particular in academia, are next documented, concluding with a summary of the prospects of the discipline

Numerical modelling of the Vaugris reservoir on the Rhône with Telemac 3D

Water Qualit