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Search Results: 1 - 10 of 189913 matches for " G. Bonnaud "
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Weibel instability-mediated collisionless shocks in laser-irradiated dense plasmas:Prevailing role of the electrons in the turbulence generation
C. Ruyer,L. Gremillet,G. Bonnaud
Physics , 2015, DOI: 10.1063/1.4928096
Abstract: We present a particle-in-cell simulation of the generation of a collisionless turbulent shock in a dense plasma driven by an ultra-high-intensity laser pulse. From the linear analysis, we highlight the crucial role of the laser-heated and return-current electrons in triggering a strong Weibel-like instability, giving rise to a magnetic turbulence able to isotropize the target ions.
Electromagnetic fluctuations and normal modes of a drifting relativistic plasma
C. Ruyer,L. Gremillet,D. Bénisti,G. Bonnaud
Physics , 2013, DOI: 10.1063/1.4829022
Abstract: We present an exact calculation of the power spectrum of the electromagnetic fluctuations in a relativistic equilibrium plasma described by Maxwell-J\"uttner distribution functions. We consider the cases of wave vectors parallel or normal to the plasma mean velocity. The relative contributions of the subluminal and supraluminal fluctuations are evaluated. Analytical expressions of the spatial fluctuation spectra are derived in each case. These theoretical results are compared to particle-in-cell simulations, showing a good reproduction of the subluminal fluctuation spectra.
Nonlinear dynamics of the ion Weibel-filamentation instability: an analytical model for the evolution of the plasma and spectral properties
C. Ruyer,L. Gremillet,A. Debayle,G. Bonnaud
Physics , 2015, DOI: 10.1063/1.4913651
Abstract: We present a predictive model of the nonlinear phase of the Weibel instability induced by two symmetric, counter-streaming ion beams in the non-relativistic regime. This self-consistent model combines the quasilinear kinetic theory of Davidson et al. [Phys. Fluids 15, 317 (1972)] with a simple description of current filament coalescence. It allows us to follow the evolution of the ion parameters up to a stage close to complete isotropization, and is thus of prime interest to understand the dynamics of collisionless shock formation. Its predictions are supported by 2-D and 3-D particle-in-cell simulations of the ion Weibel instability. The derived approximate analytical solutions reveal the various dependencies of the ion relaxation to isotropy. In particular, it is found that the influence of the electron screening can affect the results of simulations using an unphysical electron mass.
Droit de réponse à propos du compte-rendu de Mohamed Bakhouch
Mary Bonnaud
Revue des Mondes Musulmans et de la Méditerranée , 2012,
Abstract: Dans la Revue des mondes musulmans et de la Méditerranée, Monsieur Mohamed Bakhouch publie un article sur mon livre. Je lui sais gré de sa lecture attentive et minutieuse. Le temps même qu'il a d y consacrer est un véritable hommage. Et comme il n'aborde guère le contenu et encore moins la méthode de lecture des textes, je tiens donc pour acquis qu'il les approuve. Autre hommage, qui, plus qu'à moi, s'adresse aux arabisants qui ont encouragé mon travail, Monsieur Abdellah Bounfour, Madame Ge...
Les besoins et l'organisation de formations complémentaires pour les doctorants en EEA
Bonnaud Olivier
J3eA : Journal sur l'Enseignement des Sciences et Technologies de l'Information et des Systèmes , 2011, DOI: 10.1051/j3ea/2011020
Abstract: Depuis la mise en place du processus de Bologne en Europe cherchant à harmoniser les études supérieures et depuis l’arrêté Ministériel du 07 ao t 2006 relatif aux études doctorales, de fa on analogue à la plupart des pays développés (anglo-saxons et de l’extrême orient) les études doctorales correspondent d’une part à la préparation de la thèse et d’autre part à des enseignements complémentaires. Ces formations constituent un complément au dipl me mais aussi doivent préparer le futur docteur à la vie active aussi bien dans les organismes de recherche et d’enseignement supérieur que dans les centres de recherche et développement des entreprises. Cette présentation rappelle les besoins en compétences et savoir-faire des docteurs, précise les formations et la gestion des prises en compte au niveau des écoles doctorales, et donne des exemples de formations réellement organisées surtout dans le domaine de l’EEA.
The Challenges of Microelectronics for the Future Digital Society: The Roles of Thin Film Technologies and of the Higher Education  [PDF]
O. Bonnaud
Journal of Materials Science and Chemical Engineering (MSCE) , 2019, DOI: 10.4236/msce.2019.712006
The new digital society is based on Internet of Things (IoT) and related connected objects are becoming more prevalent around the world. This evolution implies innovation in many areas of technology, the heart of which is microelectronics. Connected objects involve many technological components and functions that are directly dependent of the microelectronics capabilities. If the perspectives are exciting, several challenges are appearing. The first is related to the energy consumption of all these objects, which will become enormous by 2030, and unrealistic by 2040. The second is human resources concern. The future engineers and PhD will have many obstacles to overcome. A way to face these challenges is to involve more and more new thin film technologies that must be combined with VLSI ones, and to better train students to this domain with enough know-how and with a large spectrum of knowledge suitable for multidisciplinary applications. The French national network for Higher Education in microelectronics has adopted this strategy. After presentation of the challenges, this paper deals with the innovative activities of the French network focused on thin film technologies, in order to face the challenges in a short future.
Des usines à la campagne aux villes industrielles
Laure Bonnaud,Emmanuel Martinais
Développement Durable et Territoires , 2005,
Abstract: L’objet de cet article est de retracer sociologiquement l’histoire du droit des installations classées ou plut t de la partie de ce droit qui concerne l’urbanisation autour des établissements dangereux et qui entend ainsi encadrer les relations entre la ville et l’industrie. Cette perspective permet d’envisager deux aspects complémentaires de cette question : d’une part, on examine le droit comme une fa on de représenter un problème et notamment comment la place de la question urbaine y a été pensée et définie ; d’autre part, on s’intéresse aux règles juridiques comme des outils, des ressources de catégories, de concepts qui définissent des cadres pour l’action publique. Ainsi, l'histoire du droit des installations classées contribue à mettre en lumière la fa on dont la gestion de la proximité ville/industrie articule en permanence (mais selon des modalités qui varient au fil du temps) les dimensions sociales, économiques et environnementales qui permettent aujourd'hui d'appréhender et de définir le développement durable. The main aim of this paper is to relate the history of a part of the environmental French law, the one which govern the urban development in the vicinity of the dangerous chemical plants. From a sociological point of view, two aspects of this issue may be simultaneously analysed. In one hand, we examine the law as a way to represent the problem of cohabitation between urban area and industry: how this question has been successively thought out and defined? On the other hand, we take an interest in the juridical rules considered as tools, resources and concepts for public management. According to this approach, the history of this part of French law highlight how urban planning and risk management permanently link the social, economical and environmental dimensions of sustainability. But it shows also that those three factors play a part that vary from time to time.
A Human Body Analysis System
Girondel Vincent,Bonnaud Laurent,Caplier Alice
EURASIP Journal on Advances in Signal Processing , 2006,
Abstract: This paper describes a system for human body analysis (segmentation, tracking, face/hands localisation, posture recognition) from a single view that is fast and completely automatic. The system first extracts low-level data and uses part of the data for high-level interpretation. It can detect and track several persons even if they merge or are completely occluded by another person from the camera's point of view. For the high-level interpretation step, static posture recognition is performed using a belief theory-based classifier. The belief theory is considered here as a new approach for performing posture recognition and classification using imprecise and/or conflicting data. Four different static postures are considered: standing, sitting, squatting, and lying. The aim of this paper is to give a global view and an evaluation of the performances of the entire system and to describe in detail each of its processing steps, whereas our previous publications focused on a single part of the system. The efficiency and the limits of the system have been highlighted on a database of more than fifty video sequences where a dozen different individuals appear. This system allows real-time processing and aims at monitoring elderly people in video surveillance applications or at the mixing of real and virtual worlds in ambient intelligence systems.
Hydrochemistry of Groundwater in the North Numidian Mercurial Zone (Azzaba),North East Algeia: Effect of Mercury Contamination of Population
Benhamza Moussa,Kherici Nacer,Picard-bonnaud Francoise,Nezzal Abdelmalek
Online Journal of Earth Sciences , 2012,
Abstract: The mercury ore deposit of Azzaba is located on the northern flanc of the limestone Chain, south of Azzaba town, North East Algeria. The study area is characterized by two aquiferous. The Oligocene aquifer is composed of fissured sandstone alternating with argillaceous layers whereas the deep aquifer of Paleocene-Eocene age and sediments consisting of sandstones, limestones and conglomerates-breccias. These two aquifers are separated by the impermeable rocks of the Paleozoic and the Lutetian-Priabonian, which represents the mercurial mineralization of Cinnabar (HgS), characterized by breccias limestone, clays and limestone. Nineteen springs and wells from the two aquifers were sampled for chemical analyses. The most dominant facieses are bicarbonated calcic, sulfated calcic and chlorided sodic. Water of the Oligocene aquifer shows high Hg contents (up to 80 g.L 1) whereas in the deep aquifer, Hg contents do not exceed 7 g.L 1 though the litho-stratigraphic facies with a high Hg Clarke are located in the deep aquifer.The calculated coefficient of Hg in the area is moderate following the stability of cinnabar, compared to those of Zn and Cu wich are much higher.The increase of Hg in water of the Oligocene is not the result of the leaching of geological formations (Cinnabar). The mean urinary inorganic Hg rate in the plant worker is about 650 g.G 1 of creatinine. Clinical signs of Hg contamination within school children are compared between those of Azzaba region and those of Annaba, located 80 km East of Algeria taken as a non contaminated reference. School children of Azzaba region have a mean rate of 2.50 g.G 1 compared to 0.45 g.G 1 for those of Annaba.The mercury norm is largely exceeded in groundwater as well as in population living in the Azzaba region.
Post-retirement health surveillance after occupational exposure to abstestos and wood dust: first results of the Spirale program
Nachtigal M,Bonnaud S,Gaignon A,Serrano A
Pratiques et Organisation des Soins , 2009,
Abstract: The estimation of new cancers due to professional exposures each year in France is between 15,000 and 20,000; about 25% of retired males have been professionally exposed to asbestos, and 8% to wood dust. Since 1995, a post-professional medical followup (SPP) exists, but is widely unknown. The Spirale program follows two aims: of public health, identifying eligible persons for SPP and taking them to it, and of epidemiological research on professional exposures long time effects and advantages from SPP.Spirale is leaded by the Inserm/CNAMTS 687 Unit which locates former employees exposed to carcinogens during their professional life course, using a self questionnaire, and the Assurance maladie (National Health Insurance) Health care centers (CES) which evaluate and confirm exposures and help people to obtain SPP.The Spirale pilot period took place in 13 CES in 2006 and 2007, targeting about 50000 new retired males; it identified 1,751 asbestos professional exposures and 684 wood dust ones. It raised asbestos SPP requests by 45% and wood dust ones by 600%. Besides, about 85% of exposed persons have agreed for an epidemiological follow-up.Looking for a whole territory spread order, the Assurance maladie decided to continue Spirale in 2008 in the 13 pilot CES.
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