Search results for "Température"
showing 10 items of 44 documents
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…
Time of emergence of Mediterranean summer maximum temperature.
2016
The time at which the signalof climate change emerges from the noise of natural climate variability is called “time of emergence”. This timeis analyzed here based on summertime mean maximum temperature in the Mediterranean basin for RCP8.5 andRCP4.5 scenarios. This time would be around 2040-50 (2060-70) in the eastern (western) basin. Differencesbetween the optimistic and pessimistic scenarios give a mean shift of around 15 years with the time ofemergence occurring earlier for RCP8.5 scenario.
Timing and patterns of the ENSO signal in Africa over the last 30 years: insights from normalized difference vegetation index data.
2014
Abstract A more complete picture of the timing and patterns of the ENSO signal during the seasonal cycle for the whole of Africa over the three last decades is provided using the normalized difference vegetation index (NDVI). Indeed, NDVI has a higher spatial resolution and is more frequently updated than in situ climate databases, and highlights the impact of ENSO on vegetation dynamics as a combined result of ENSO on rainfall, solar radiation, and temperature. The month-by-month NDVI–Niño-3.4 correlation patterns evolve as follows. From July to September, negative correlations are observed over the Sahel, the Gulf of Guinea coast, and regions from the northern Democratic Republic of Congo…
Thermal remote sensing from Airborne Hyperspectral Scanner data in the framework of the SPARC and SEN2FLEX projects: an overview
2009
Abstract. The AHS (Airborne Hyperspectral Scanner) instrument has 80 spectral bands covering the visible and near infrared (VNIR), short wave infrared (SWIR), mid infrared (MIR) and thermal infrared (TIR) spectral range. The instrument is operated by Instituto Nacional de Técnica Aerospacial (INTA), and it has been involved in several field campaigns since 2004. This paper presents an overview of the work performed with the AHS thermal imagery provided in the framework of the SPARC and SEN2FLEX campaigns, carried out respectively in 2004 and 2005 over an agricultural area in Spain. The data collected in both campaigns allowed for the first time the development and testing of algorithms for …
Quantification des hauteurs de neige et des températures de l'air à la surface d'un glacier : du terrain à l'interpolation, confrontation de méthodes
2009
Quantifying snow cover and surface air temperature on a glacier is usually based on point data. The density of point measures is dependent on the local context. Interpolation brings the opportunity to generate a continuous surface. This surface can be used to derive a global measure for the whole glacier. These measures (total snow water equivalent, average thermal state) are integrated in glaciological and hydrological equations. Interpolation also renders the spatial variations of processes and provides information on inaccessible or not-monitored zones. Using the example of an arctic glacier, several interpolation methods were tested and compared. These methods were applied to snow drill…
Understanding of the phenomena involved in the inactivation of bacterial spores by a process combining high pressure and heat treatment
2022
High Pressure Processing (HPP) is an established food processing technique for maintaining food quality while inactivating vegetative forms of pathogenic and spoilage bacteria. However, bacterial spores are very resistant to pressure, which requires the development of a strategy combining HPP with another modality (pressure cycling, heat treatment) to increase spore destruction. Currently, the combination of these processes are not implemented at an industrial scale due to the technically complex implementation and uncertain results given the diverse and contradictory literature on the level and mechanisms of spore inactivation by HP. The elucidation of spore inactivation mechanisms by pres…
Configurations spatio-temporelles des températures et des précipitations au printemps et en été 2003 en Bourgogne : mesures Météo France et simulatio…
2010
International audience; Contexte : En Bourgogne, un collectif pluridisciplinaire piloté par Alterre travaille la question de l'adaptation au changement climatique. Une confrontation entre deux saisons végétatives (1991 et 2003) sélectionnées comme étant représentantes des conditions moyennes actuelles (1988-2007) et futures (seconde moitié du xxie siècle) est développée sur la base d'une méthodologie multi-modèles (climatique, pédologique et hydrologique).Problématique : Au-delà des éléments connus (températures élevées et pluies peu fréquentes de 2003) l'étude vise à caractériser les écarts de conditions climatiques 2003-1991 sur l'ensemble du territoire bourguignon. Les températures de la…
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.
Efficacity of SMAT and laser shock-peening process for enhancement of titanium alloys high temperature oxidation resistance
2017
The aim of this thesis is to determine the influence of two mechanical surface treatments, the shot- peening performed with several type of balls (WC, alumina and glass) and the laser shock peening, on the high temperature oxidation resistance of two titanium alloys : alpha alloy with commercially purity (Grade 1) and aeronautical beta metastable alloy (TIMETAL-21S).After different treatments, the pieces are oxidized with different conditions: of time (between 5 hours to study the firsts times of oxidation and 3000 hours to compare with a classical aeronautical test), of temperature (600°C to 700°C) and atmosphere (dry air or oxygen).The pieces are analyzed before and after oxidation exposu…
La sensibilité des communautés microbiennes à une augmentation de la température augmente quand la biodégradabilité de la ressource organique baisse
2014
La sensibilité des communautés microbiennes à une augmentation de la température augmente quand la biodégradabilité de la ressource organique baisse. 12. Journées d'Etude des Sols