Search results for "Spatiale"
showing 10 items of 197 documents
EVASPA (EVapotranspiration Assessment from SPAce) tool: an overview
2013
International audience; Evapotranspiration (ET) is a fundamental variable of the hydrological cycle and its estimation is required for irrigation management, water resources planning and environmental studies. Remote sensing provides spatially distributed cost-effective information for ET maps production at regional scale. We have developed EVASPA too for mapping ET from remote sensing data at spatial and temporal scales relevant to hydrological or agronomica studies. EVASPA includes several algorithms for estimating evapotranspiration and various equations for estimating the required input information (net radiation, ground heat flux, evaporative fraction…), which provides a way to assess …
Résolution spatiale des MNT et qualité de l'estimation des températures et des précipitations en France
2015
DTM spatial resolution and temperature and amount of rainfall estimation in France. The spatial variationanalysis of normal temperature and amount of rainfall in France is performed by simple linear correlations where elevationis the explanatory variable. The latter is provided in seven resolutions: 250,500 m, 1, 2, 4, 8 and 16 km. The correlationcoefficient is used to assess what is the resolution that works best. Temperatures are optimally explained by the 250 mresolution, the coarser resolutions producing lower quality results. The 2km resolution best explains the spatial variation ofrainfall.
La distance en analyse spatiale : une approche axiomique
1985
L'analyse spatiale met en lumière des processus d'interdépendance où ladistance joue un rôle explicatif fondamental. Une large partie de l'analyse spatiale est consacrée à l'étude de la forme de la relation entre les phénomènes économiques et sociaux observés et la distance à des lieux privilégiés, et aux variations de cette relation. Or cette forme est en partie conditionnée par la représentation de l'espace qu'on se donne, donc par la représentation de la distance dans cet espace. La littérature offre un certain nombre de spécifications analytiques de la distance entre deux lieux repérés par leurs coordonnées, par exemple la distance euclidienne, longtemps privilégiée, et plus récemment l…
Organisation spatiale et Dégradation environnementale : croissance et agglomération
2015
Agglomération et lutte contre la délinquance: comment mesurer la lutte contre la délinquance à l'échelle des ZUS de France métropolitaine
2017
National audience; En France, peu d’études ont été menées sur le couple emploi-délinquance à une échelle spatio- temporelle fine. On peut, néanmoins, relever quelques études menées à l’échelle des départements français étudiant, par exemple, les effets du chômage sur la délinquance des jeunes (Fougères et al., 2009), ou une étude de l’accroissement de la délinquance en lien avec le marché de l’emploi menée sur plusieurs pays européens (Tranaes, 2015). Par ailleurs, on peut relever que l’impact des crises économiques majeures, comme par exemple, la crise du phylloxera au cours du XIXe siècle (Bignon et al., 2015), joue un rôle majeur à la fois sur l’activité économique et sur le taux de déli…
The Indian-French Trishna Mission: Earth Observation in the Thermal Infrared with High Spatio-Temporal Resolution
2018
International audience; The monitoring of the water cycle at the Earth surface which tightly interacts with the climate change processes as well as a number of practical applications (agriculture, soil and water quality assessment, irrigation and water resource management, etc...) requires surface temperature measurements at local scale. Such is the goal of the Indian-French high spatio-temporal TRISHNA mission (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment). The scientific objectives of the mission and research work conducted to consolidate the mission specifications are presented. Progress in modelling of surface fluxes is then discussed. The main spec…
Essay on the integration of interactions in the treatment effect evaluation : the contribution of spatial econometrics methods
2015
This thesis focuses on the integration of interactions in the estimation of the public policy’s effect. Indeed, the estimation standard methods usually rely on strong assumptions that exclude partially or completely the interaction effect both in the selection process of beneficiaries and in the performance of the policy. However, the validity of these assumptions is questionable, particularly in the context of a non-experimental policy because an individual according as it is the beneficiary or not the policy, is not isolated: he interacts with his neighborhood. Thus, the estimated effect of the policy by traditional methods is likely to be biased (underestimation or overestimation) theref…
La politique spatiale européenne
2004
Flood Detection On Low Cost Orbital Hardware
2019
Satellite imaging is a critical technology for monitoring and responding to natural disasters such as flooding. Despite the capabilities of modern satellites, there is still much to be desired from the perspective of first response organisations like UNICEF. Two main challenges are rapid access to data, and the ability to automatically identify flooded regions in images. We describe a prototypical flood segmentation system, identifying cloud, water and land, that could be deployed on a constellation of small satellites, performing processing on board to reduce downlink bandwidth by 2 orders of magnitude. We target PhiSat-1, part of the FSSCAT mission, which is planned to be launched by the …
Économétrie spatiale : l'autocorrélation spatiale dans les modèles de régression linéaire
2002
Spatial Econometrics : Automatic Spatial Correlation in Linear Regression Models. The aim of this article is to describe the tools necessary to factor in automatic spatial correlation determined by the absence of independence between geographical observations, within the framework of linear regression models. While it is often accepted that spatial data in cross-sections are independent, this assumption is rarely justified. On the contrary, it needs to be tested systematically. After explaining the ways in which to model automatic spatial correlation, we therefore describe estimation and inference procedures geared to econometric models that factor in this effect explicitly. Lastly, we prop…