Search results for "chaleur"
showing 10 items of 18 documents
Experimental study and physical modeling of simultaneous heat and moisture transfer in bio-sourced insulating materials.
2019
The conventional heat transfer models are not sufficiently suitable for thermal characterization of bio-sourced thermal insulating materials due to their strongly hydrophilic nature. The proposed work in this PhD thesis aims to answer this problem with experimental and theoretical approaches of coupled heat-moisture transfers. In the experimental approach, a thermal insulating material based on Flax Fiber Felt (FFF) is developed and then characterized at different hygrometric conditions with an asymmetric hot plate device. The humidity diffusion characterization of the samples is done using the GAB, GDW and Park theoretical moisture adsorption isotherm models. In the theoretical approach, a…
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 …
Durée et fréquence des vagues de chaleur en Afrique tropicale septentrionale selon 5 indices de chaleur.
2019
Thermal extremes generate health risks that are increasingly taken into account, including in tropical Africa. This work compares the duration and the frequency of spring heat waves (HWs) in West Africa according to 5 indices: Warm Spell (WS), Heat Index (HI) with and without the relative humidity, Apparent Temperature (AT), and Excess Heat Factor (EHF). The daily relative humidity and temperature data (minimum, maximum, dew point are provided by the GSOD database for the period 1973-2014 and cover 145 stations spread over a large African area (3-24°N; 24°W-36°E). The results show that the duration of the HWs is short on the coast (3 days) and they last longer inland the continent and in th…
Durée et fréquence des vagues de chaleur en Afrique tropicale septentrionale selon 5 indices de chaleur
2019
Thermal extremes generate health risks that are increasingly taken into account, including in tropical Africa. This work compares the duration and the frequency of spring heat waves (HWs) in West Africa according to 5 indices: Warm Spell (WS), Heat Index (HI) with and without the relative humidity, Apparent Temperature (AT), and Excess Heat Factor (EHF). The daily relative humidity and temperature data (minimum, maximum, dew point are provided by the GSOD database for the period 1973-2014 and cover 145 stations spread over a large African area (3-24°N; 24°W-36°E). The results show that the duration of the HWs is short on the coast (3 days) and they last longer inland the continent and in th…
Les vagues de chaleur au Sahel : définition et principales caractéristiques spatio-temporelles (1973-2014).
2016
A definition of heat waves (HW) relevant for dry tropical regions is proposed and tested in the Sahel (i.e. duration,intensity and frequency). The Heat Index (HI derivative of Steadman’s (1979) formula) is calculated on dailydata of 145 West African stations from the GSOD database over the period 1973-2014. HWs recorded inSahelian and Sudanese climates mainly occur in boreal spring, i.e. April-May-June. They are more frequentsince 1998 (+ 8% very hot days, T90p) and they become longer (+1.2 days per decade) and more intense (from+0.3 to 0.4 ° C / decade respectively Sudanese and Sahelian climate) on the end of the period 1973-2014.
Numerical simulation of heat transfer, fluid flow and elements diffusion during laser welding of dissimilar steels
2017
The design of new steel grades offering equivalent mechanical performances for lower thicknesses and the added value with the possibility to join two different steel grades, require development and control of joining processes. Thanks to high precision and good flexibility, the laser welding became one of the most used processes for joining of dissimilar welded blanks. The prediction of local chemical composition in the weld formed between dissimilar steels in function of the welding parameters is essential because the dilution rate and the distribution of alloying elements in the melted zone determine the final tensile strength of the weld. The goal of the present study is to create and to…
Mesures de la température et spatialisation de l’Ilot de Chaleur Urbain à Dijon
2015
The Territorial Climate Energy Plan (PCET) of the agglomeration of Dijon (Grand Dijon) includes ameasurement campaign (6 June to 28 September 2014). 50 Hobo proV2 thermometers were deployed. The selection of siteswas carried out so that the different types of urban environment (Oke, 2006) are documented. The Urban Heat Island (UHI)is discernible mainly at night, when radiative conditions are well established the day before. It is estimated to 1°C onaverage for the summer, 3-4°C during nights of fine weather. It reached 6°C during the warmest periods of the 2014 summer.A cool axis through the agglomeration shows that vegetation and water can sensibly mitigate the ICU effect.
Sensitivity of a climate model to urban form : application on Dijon Métropole
2020
The urban environment is at the crossroads of two complex systems with different temporalities : climate and society. The urban climate is a modification of the climate caused by the presence of a city. The most successful expression of this climate change by the presence of the city is the phenomenon of Urban Heat Island (UHI). In a global context of adaptation and mitigation to climate change and urban development, this phenomenon of ICU tends to increase, and its health impacts on populations to become more prominent. This work is aimed at improving the knowledge of the impact of urban form and urban development on the intensity of the UCI through the implementation of a decision support…
Impacts d’une meilleure description de la végétation urbaine sur des simulations du climat urbain avec SURFEX-TEB.
2022
Le réseau MUSTARDijon offre la possibilité de procéder à une cartographie fine des températureshoraires sur Dijon Métropole. La méthode proposée ici repose sur des régressions linéaires multiplesmobilisant deux familles de prédicteurs : des descripteurs du relief et des descripteurs de l’occupation dusol. L’application porte sur la canicule de l’été 2020 (6-9 août). Deux configurations sont comparées. L’une,en mode recherche, laisse la possibilité aux descripteurs de varier dynamiquement en fonction de leurpertinence statistique, l’autre, en mode opérationnel, impose les 5 mêmes descripteurs en entrée. Entermes de performance statistique ou de structure spatiale, l’impact de la méthode n’es…
Étude des températures simulées avec Méso-NH : sensibilité à l’artificialisation des sols à Grenoble et Lyon.
2022
International audience; La modélisation atmosphérique à très fine échelle permet d’analyser la dynamique de l’îlot dechaleur urbain en contexte de topographie complexe. Deux simulations (Urbaine et Non-Urbaine) mettenten évidence les effets associés à l'urbanisation. La taille des agglomérations, dans le cas de Lyon etGrenoble, n'influence pas la différence de température entre les deux simulations. Les conditions destabilité influencent fortement ces différences. L'ICU peut être intensifié par l'affaiblissement du vent oul’effet de piégeage et/ou le développement d’une couche d’inversion.