Search results for "modèles"

Fractals and geography

2007

GEOV1: LAI, FAPAR essential climate variables and FCOVER global time series capitalizing over existing products. Part 2: Validation and intercomparis…

2013

International audience; This paper describes the scientific validation of the first version of global biophysical products (i.e., leaf area index, fraction of absorbed photosynthetically active radiation and fraction of vegetation cover), namely GEOV1, developed in the framework of the geoland-2/BioPar core mapping service at 1 km spatial resolution and 10-days temporal frequency. The strategy follows the recommendations of the CEOS/WGCV Land Product Validation for LAI global products validation. Several criteria of performance were evaluated, including continuity, spatial and temporal consistency, dynamic range of retrievals, statistical analysis per biome type, precision and accuracy. The…

Modelling and development of a generic observatory to harvest and analyze big data

2021

Big Data fascinate, both because of the value they hold that can provide a significant advantage in decision-making, and because of the challenges that their exploitation represents. These challenges are present at several levels of analytics workflows. At the level of the creation of software architectures, the volume and the velocity require at least enough performance to handle the ingestion and storage of data. The data variety has also an impact, as several new storage systems have emerged, each one corresponding to a specific need. The polystores are systems that integrate this diversity, to gain flexibility compared to the data warehouses, now too rigid. However, this diversification…

Climate change impact on the West African monsoon from June to October.

2015

Sixteen CMIP5 models are used toanalyse how climate changes over the West African Monsoon region between a “future period”, defined from 2031 to 2070under the rcp4.5 emission scenario, and the “current period”, defined from 1960 to 1999 under the historical emissionscenario. The results show an increase of the September to October rainfall amounts. Circulation anomalies include of anincreases of sea-level pressure over the Mediterranean Sea and Europe that allow a strengthening of the moisture flux fromEuro-Mediterranean regions into the Sahel. These changes are stronger in autumn.

The climate change effect on the african monsoon region : evolution of the precipitation and atmospheric fields in the CMIP3 and CMIP5 simulations un…

2013

The fourth IPCC report in 2007 established the synthesis of previously published work onthe effects of climate change on global and regional scales. It shows in particular that no consensuscan be found with regard to the future of rainfall — and atmospheric dynamics- associatedwith region — African monsoon. This dissertation revisits this issue in the light of new dataand using an approach avoiding over-representation of the number of simulations available forone type of model and taking into account the diversity of models and their evolution in time :twenty general circulation models (GCMs) participating in the exercises CMIP3 (twelve GCMs)and CMIP5 (eight GCMs) under the A1B emissions sc…

Tropical Temperate Toughs over southern Africa : mechanisms and evolution in response to climate change (2010-2099)

2014

In the Southern Hemisphere, Southern Africa and the south-west Indian Ocean are one of the three preferred regions where interactions between the tropics and midlatitudes develop. This is the South Indian Convergence Zone (SICZ), where northwest-southeast oriented cloud bands form at the synoptic scale (between 3 and 5 days). These bands are mainly found during the austral summer and are commonly referred to as tropical temperate troughs (TTTs). This research aims at improving our knowledge related to TTTs, with a study on the dynamics associated with these systems, and an analysis of their possible evolution during the 21st century.The first part of this thesis aims at identifying favorabl…

Study of the biochemical composition and physico-chemistry of a protein-based food model of Parkia biglobosa

2022

In West Africa, the seed of the cowpea (Parkia biglobosa) is used in traditional pharmacopoeia and especially in human food as a condiment. This legume is very rich in proteins and lipids and remains a poorly exploited source of protein. Our thesis focuses on the valorization of Néré seeds for the development of new protein-rich products of plant origin as an alternative to the use of soybean as a basic ingredient. The objectives were : (i)biochemical and physicochemical characterization of protein isolates from Néré seed flour according to the extraction process, (ii) selection of proteolytic lactic acid bacteria capable of fermenting Néré juice, reducing anti-nutritional factors in order …

Apport d'un formalisme psychologique à la modélisation des préférences individuelles. Application aux choix d'itinéraires pédestres

2007

With the increasing need for a sustainable mobility, pedestrian movement analysis lately increased. In an attempt to get a more detailed knowledge of urban pedestrian movement, we intend to model the pedestrian's route choices. Our first approach is based on simple economic models, the discrete choice models. A psychological theory is added in the process in order to improve the pedestrian behaviour simulation. Results show that psychological formalisms are useful for individual choices' modelling. For this reason they could be used more systematically in the framework of urban mobility

Comprehending city and its production in Africa through a systemic approach : example of the city of Diamniadio, Dakar

2022

For a long time, the analysis of the production of the city in Africa was based on an exogenous perception according to urban models theorized and experimented with in the Occidental countries, then diffused and applied through different mechanisms in the South, bearing witness to historical relations - through the making of the colonial city - and present relations - in the context of the making of new towns. After independence, researchers looked at the redefinition of the city in Africa with its complexity and plurality according to geographical and historical trajectories, proposing new urban theories that were more nuanced and linked to local and contextual realities. Therefore, follow…

Spatio-temporal saliency detection in dynamic scenes using color and texture features

2014

Visual saliency is an important research topic in the field of computer vision due to its numerouspossible applications. It helps to focus on regions of interest instead of processingthe whole image or video data. Detecting visual saliency in still images has been widelyaddressed in literature with several formulations. However, visual saliency detection invideos has attracted little attention, and is a more challenging task due to additional temporalinformation. Indeed, a video contains strong spatio-temporal correlation betweenthe regions of consecutive frames, and, furthermore, motion of foreground objects dramaticallychanges the importance of the objects in a scene. The main objective o…