Search results for "Modélisation"
showing 10 items of 222 documents
Modélisation des objets urbains pour l'étude des dynamiques urbaines dans la longue durée
2007
The use of GIS to study the spatial evolution of pre-industrial cities over the "longue durée" requires rigorously formalising heterogeneous data from different sources into robust entities. An initial model using the HBDS (Hypergraph Based Data Structure) method enabled us to distinguish social and spatial features. In this paper we develop a specific model for the temporal dimension. The definition of urban objects using social, spatial and temporal features enhances the study of urban dynamics of change over the "longue durée".
Microstructure-process relationship and reactivity at the nanoscale : a molecular dynamics study of Ni, Ni-Al, and Ti-Al metallic systems
2023
The process-microstructure relationship is central in materials science because the microstructure will determine the properties of the materials developed by the processes. In our work, we focused on different metallurgical processes by adopting a description at the atomic scale. This approach allows us to detect the elementary mechanisms that are at the origin of the observed microstructures without having to postulate macroscopic mechanisms or estimate the associated parameters. In this respect, molecular dynamics simulations provide a tool for "in-situ" observation of metallic systems as long as an atomic interaction potential is available. The originality of our approach consists in mo…
Entités fonctionnelles, entités spatiales et dynamique urbaine dans la longue durée
2004
Functional Features, spatial Features and the urban Dynamic across a long Lapse of Time. Heterogeneous data from different sources are to be formalised as functional and spatial features in order to study the spatial evolution of preindustrial cities in the « longue durée ». The aim is to establish a distinction between historically relevant functional features and geographically relevant spatial features in order to produce information better adjusted to study spatial dynamics. The elements of a methodology are brought up.
Realism Score for Immersive Virtual Reality Systems and Driving Simulators
2016
International audience; Traditional 2D or 3D quality assessment methods are not sufficient to assess the realism of the outputs of a simulator/immersive virtual reality system. We propose an assessment method based on a scoring system through a new approach. The objective of this paper is to propose a score scale for any simulator or immersive display system that would represent how close to the human visual system the signals that are sent through the display are. Weighted items considered are contrast, acuity, frames per seconds, brightness, field of view and the number of color available.
Modélisation d'images agronomiques - application a la reconnaissance d'adventices par imagerie pour une pulvérisation localisée
2009
Plant (crop and weed) identification is a very active field of research in agriculture since the reinforcement of European laws about pesticide applications for a site-specific management of spraying practices. A new crop/weed simulation model was developed to allow the evaluation of crop/weed spatial identification methods from imaging. Considering multiples agronomic parameters – crop location, weed infestation rate, weed spatial distribution – the first step of this model allows the simulation of an infested crop field. Then, in a second step, a world to camera transformation is applied to allow every kind of picture (with or without perspective effect). The validation of this model was …
Contribution to the study of spray formation
2012
The work of this thesis aims to provide and validate tools useful to study and understand the phenomena involved in the injection of fuel, mainly focused on intra-flow injector. These tools are numeric and simulate the formation of a spray. A first part focuses on zero-dimensional modelling. Models which predict these following characteristics of spray like the spray angle, the spray penetration or the liquid length are compared with experimental data. The conclusions are that zero-dimensional modelling provides good results very quickly in some cases. Although, a better understanding of the influence of cavitation on the spray, which requires an understanding of the intra-flow injector, co…
Agent-based model for the rescheduling of Individual and collective daily activities under uncertainties
2020
Daily activity schedule are popular for people duringdaily life. While, when executing the schedule on the real road network, there are always some disruptions disturbing the planned schedule. To deal with this problem, daily activity rescheduling is necessary. This thesis regards the disruptions from the activity schedule execution environment as unexpected events (uncertainties). It establishes agent-based models to simulate the activity rescheduling decision process from the aspects of individual activity rescheduling and joint trip renegotiating.For the individual activity rescheduling, the model in this thesis wants to explore the relationship between a pair of episodes (two connected …
Tectonique et architecture des bassins intracratoniques Paléozoïques : impact sur l’enregistrement sédimentaire et la géométrie des réservoirs associ…
2019
The Paleozoic Saharan platform including the peri-Hoggar Basins (i.e. Murzuq, Illizi, Mouydir, Ahnet, Reggane and Tim Mersoï basins) are defined as intracraonic basins. Their histories have been dominated by slow long-wavelength vertical motions leading to overall low subsidence rate (i.e ca. 10 m/Ma to 50 m/Ma) and accumulation of an extensive cover of platformal sediments (i.e. shallow deposits environments), rhythmed by pulsatile periods of increasing and decreasing rate probably triggered by regional geodynamic events. The vertical motions of the platform produced several arches also called domes, swells, highs, ridges (e.g. the Tihemboka, Amguid El Biod, Arak-Foum Belrem and Azzel Matt…
Physico-chemical evolution of low-pH cements : influence of the temperature and the retention mechanisme of alkalins
2010
Because of their high alkalinity, Portland cement (OPC)-based materials may have deleterious effects in an underground waste repository. A solution would be to use low-alkalinity cements (also referred as low-pH cements) generating interstitial solutions with a reduced pH (11 instead of 13.5 for OPC), and thus showing an improved chemical compatibility with the repository environment. In this work, the investigated formulations were based on binary (OPC / silica fume) or ternary (OPC / silica fume / slag or fly ash) blends, with high substitution levels of CEM I (from 30% to 80%). This research project met two main objectives: (i) study the chemical evolution of low-pH cements at 50°C or 80…
Magnesium silicate hydrate (M-S-H) characterization : temperature, calcium, aluminium and alkali
2017
The various options to store radioactive wastes in deep geological strata considered in France or Switzerland include the use of large volumes of cementitious materials for infrastructure in contact with argillaceous rocks. So-called low-pH binders were developed to minimize disruption to the surrounding rock by the alkaline plume. Studies conducted on the interaction zone between concrete and clay systematically highlighted the formation of magnesium silicate phases including magnesium silicate hydrate (M-S-H) at the interfaces, which can presently be modeled only partially due to incomplete thermodynamic data. The purpose of this study was to characterize these phases in temperature, alum…