Search results for "Densité."
showing 10 items of 22 documents
An ecological multi-Level theory of competition for resources used to analyse density-dependence effects in fruit production
2014
International audience; Lescourret and Génard (2003) developed a multi-level theory of competition for resources applied to fruit production, considering that any collection of unit parts (cells or seeds in a fruit, fruits in an infructescence or in a tree...) can form a population and the population is subject to competition, whatever the level of organization. The principles of the theory are that the mass of each unit decreases when the number of units in the population increases and that the total mass of the population increases as the number of units increases until it reaches a maximum, after which it decreases. A three-parameter model based on that theory was used to analyse the lev…
The Bronze Age in Lorraine: a proposed model of the settlement
2022
Thirty years of assiduous preventive archaeology practice in Lorraine have built up a stock of data that can be used for numerous archaeological problems with a spatial focus.For the Bronze Age, as for the other chronological periods, the archaeological occupations discovered during diagnostics and excavations are strongly correlated with current developments (motorways, TGV, housing estates, quarries, etc.). These occupations must be discussed in order to estimate their spatial representativeness. Similarly, the landscape characterisation, in which the occupations highlighted are situated, is an important step in defining the types of settlement.As most of the data comes from the national …
Economie urbaine et densités", contribution au Rapport final "Formes et enjeux de la densification, vers un aménagement durable des territoires bourg…
2015
DREAL Bourgogne, Ademe Bourgogne et Conseil Régional de Bourgogne (2013-2015), juin 2015.;
Population dynamics and genetics of European Pond Turtle Emys orbicularis
2013
Dispersal, characterized by the movements of individuals in space leading to gene flows, allows populations to connect. The study of dispersal has become of essential importance to predict the consequences of global changes on the population structures and dynamics. Species with limited dispersal, such as chelonians, are particularly threatened by these phenomena. Our study aimed at analyzing the dispersal of the European pond turtle (Emys orbicularis), in decline in Europe, in a habitats fragmentation context and determining the causes of this behavior through analysis of population dynamics and genetics. Our results show, firstly, that the slow generation time in Emys orbicularis (about 1…
Empirical tests of the multicentric urban models
1999
Since the seventies the effects of city size growth and diversification of economic activities on the multipolarisation of economic activities have questioned the theoretical and empirical appropriateness of the monocentric urban pattern to explain and describe the spatial organization of the modern metropolitan areas. New assumptions were based on multicentric and nonmonocentric urban economics models, which have become the core of new economic geography analysis during the nineties. At the same time, a lot of empirical studies have attempted to describe the urban economic patterns of North American metropolitan areas. Using this empirical literature, the aim of this paper is to propose a …
Organisation spatiale et densités urbaines : une application à l'agglomération du Grand Dijon
2017
Cet article s’intéresse aux différentes formes et mesures de l’intensité de l’occupation de l’espace. Bien que l’indicateur le plus utilisé soit le ratio de densité brut de population, cet indicateur n’est pas suffisant pour qualifier l’occupation d’un espace. En effet, la densité revêt de multiples facettes. Il est possible de distinguer des densités de contenants (bâti) et de contenu (population, emplois) et différentes mesures peuvent être mobilisées pour quantifier cette occupation spatiale. Nous nous proposons dans cet article de mesurer et qualifier les densités urbaines – de population et de bâti – en proposant une mesure plus juste de l’intensité de l’occupation de l’espace au trave…
Synthesis of low density foam shells for inertial confinement fusion experiments
2011
This work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60°C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between …
Urban densities and economic analyse of residentials choices
2016
The thesis is focused on urban growth control challenge through the Compact City model and its key spatial characteristic: the density. This work deals both with a theoretical, methodological and empirical approach. First, we place ourselves in the theoretical framework of Urban Economic addressing agents’ location choices. We mobilize these theories to identify the key determinants of residential location (employment center, spatial amenities, housing’s service) and analyze the spatial organization that follows (dense or spread). This literature leads us to consider different types of density: structural density, population density and social density. This thesis highlights various methodo…
Analyse et Estimations Spectrales des Processus alpha-Stables non-Stationnaires
2006
In this work a new spectral representation of a symmetric alpha-stable processes is introduced. It is based on a covariation pseudo-additivity and Morse-Transue's integral with respect to a bimesure built by using pseudo-additivity property. This representation, specific to S$\alpha$S processes, is analogous to the covariance of second order processes. On the other hand, it generalizes the representation established for stochastic integrals with respect to symmetric alpha-stable process of independent increments. We provide a classification of non-stationary harmonizable processes; this classification is based on the bimesure structure. In particular, we defined and investigated periodicall…
Towards calibration transfer for quantitative analysis of nuclear materials by LIBS
2018
To ensure the quality of their products, manufacturers of nuclear materials currently rely on wet chemistry methods coupled with ICP-MS and ICP-AES. These methods are slow and sometimes hard to implement, which leads the manufacturers to seek new possibilities of online, fast and direct preliminary quality control. Thus, the issue of quantifying metal impurities in both uranium and plutonium matrices by LIBS has been raised. But the lack of calibrated samples and the harsh security constraints hinder any possibility of complete analytical development on these materials. Therefore, we propose a method relying on calibration transfer from several non-nuclear metal matrices to uranium and plut…