Search results for "Keyword"
showing 10 items of 404 documents
Système sémantique pour la customisation dynamique des modèles d'information de la PLM
2013
We live in the information age. Data has become an essential asset for most everyday situations and business interactions. The need to share data, to generate information, and create new knowledge from that data is common to all fields of research and all economic activity. Managing data is a critical, and sometimes costly, process. When not properly defined, data might become incomplete, inconsistent or, even worse, unusable. Requirements for data evolve and we must define new data or update existing data over the entire data lifecycle. Evolving data requirements is an important issue and a technological challenge as it is not possible to define, in advance, information structures that mee…
Characterisation of mechanical behavior of a sub surface drilled polymer, under hertzian contact load
2013
This research concerns the understanding of the sub-surface behaviour of a component presenting controlled heterogeneities and subjected to a Hertzian type load. The purpose is to qualify the stress field in the subsurface. Practically, defects of cylindrical shape are located where the stress field is maximal in sub surface. The contact is sized to be able to observe, by photoelasticity, the stress field and to develop a numerical model to simulate the behaviour (static and dynamic) of the friction area. It is highlighted that the presence of a hole on the z axis of symmetry (x = 0) is the dominating factor. The characteristics which allow decreasing the shearing stress on the symmetry axi…
Optimal control and applications to orbital transfer and almost-riemannian geometry
2010
In this thesis we focus on optimal control techniques as well as geometric control techniques applied to the orbital transfer problem and to almost-Riemannian geometry. In these cases, Pontryagin’s Maximum Principle allows to analyse the extremal flow of affine control systems.In the case of a satellite with low-thrust propulsion, averaging techniques give an approximated system. Averaging is explicit in the energy minimization case and is directly related to almost-riemannian problems. The geometric analysis of such problems is generalized by the study of metrics on the two-sphere of revolution. In this way it is possible to classify the situations considering the transcendance of the solu…
Etude expérimentale et modélisation thermodynamique du système CaO-SiO2-(Al2O3)-H2O
2012
The aim of this work is to build a thermodynamic model at 25°C to describe the main hydrates of ordinary Portland cement with or without supplementary cementitious materials (SCM) : calcium hydrosilicates. With high aluminium content, SCM in blended cements modify the nature and the composition of the hydrates of cement paste.The simplified model system CaO-SiO2-H2O was studied by synthesising of C-S-H with identical protocol and analysis. We distinguished, hydration solutions undersaturated and supersaturated from Portlandite.This last system has been extended to CaO-Al2O3-SiO2-H2O system. Then, we determined the most suitable protocol to synthesize pure C-A-S-H.The nanoparticular nature a…
Development of a microwave transduction gas sensor
2013
In this work, we have developed a new gas-sensing transduction based on the propagation of microwave inside a sensitive material to detect atmospheric pollutants at room temperature. First, we present a short overview of the main gas-sensing transduction in the litterature. These techniques operate in frequency ranges different from microwaves. The dielectric permittivity is the main physical parameter in the microwave transduction. The principle is based on the excitation of a sensitive material by a microwave electromagnetic field in a propagative structure. The reflected wave is specific to the excitation's frequency. It depends on the interaction between the sensitive material and the p…
Détection automatique de chutes de personnes basée sur des descripteurs spatio-temporels : définition de la méthode, évaluation des performances et i…
2013
We propose a supervised approach to detect falls in home environment adapted to location andpoint of view changes. First, we maid publicly available a realistic dataset, acquired in four differentlocations, containing a large number of manual annotation suitable for methods comparison. We alsodefined a new metric, adapted to real-time tasks, allowing to evaluate fall detection performance ina continuous video stream. Then, we build the initial spatio-temporal descriptor named STHF usingseveral combinations of transformations of geometrical features and an automatically optimised setof spatio-temporal descriptors thanks to an automatic feature selection step. We propose a realisticand pragma…
Fonctionnalisation de surfaces métalliques par des couches minces d'oxynitrures de titane obtenues par irradiation laser sous atmosphère contrôlée et…
2013
The technological advances in areas such as automotive and aerospace industries require materials capable of withstanding demanding conditions. Surface treatments are effective tools to improve the surface properties of materials while preserving their bulk properties. Besides many conventional processes, laser treatments are efficient methods for hardening and increasing the durability of materials. This work is focused on the growth of titanium oxynitride surface layers by laser irradiation of pure titanium plates with nanosecond pulsed sources. The influence of the laser treatment conditions on the composition and the structure of these surface layers was studied. In particular, for lase…
Simulation d'images d'un futur imageur multispectral géostationaire dédié à la couleur de l'eau : étude de l'influence des angles d'observation et d'…
2011
Improvements of optical sensors now make it possible to launch medium spatial and high spectral resolution sensors on the Geostationary Earth Orbit (GEO). The GEO allows sensors to observe the Earth with high temporal resolution, unlike Low Earth Orbit (LEO) satellites. The objective of this thesis is to simulate radiance images that would be provided by a theoretical ocean color sensor, on a geostationary orbit, in order to characterize the images to be acquired, to specify the future instruments and to validate the image processing algorithms. For this purpose, we have combined a radiative transfer model for ocean waters (Hydrolight) and a radiative transfer model for the atmosphere (MODT…
ScaleSem : model checking and semantic web
2012
The increasing development of networks and especially the Internet has greatly expanded the gap between heterogeneous information systems. In a review of studies of interoperability of heterogeneous information systems, we find that all the work in this area tends to be in solving the problems of semantic heterogeneity. The W3C (World Wide Web Consortium) standards proposed to represent the semantic ontology. Ontology is becoming an indispensable support for interoperability of information systems, and in particular the semantics. The structure of the ontology is a combination of concepts, properties and relations. This combination is also called a semantic graph. Several languages have bee…
SIGA3D : modélisation, échange et visualisation d'objets 3D du bâtiment et d'objets urbains géoréférencés ; application aux IFC pour la gestion techn…
2012
This thesis defines a new approach in urban and building facility management. A production and information management process of the building, its immediate environment and urban objects has been defined. It allows to manage these objects throughout their life cycle, in a concept called Urban Facility Management. This technology relies on an Urban Information Model to model all the information of cities and buildings in a dynamic and evolutive ontology. A mechanism for geometric and semantic levels of detail has also been defined to support the scalability of such a system. Indeed, the number of objects to be managed in a scene, compared to a building modeling system, is much higher, as the…