Telespazio France

Toulouse, France

Telespazio France

Toulouse, France

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Tavernier V.,École Centrale Lyon | Millet S.,École Centrale Lyon | Henry D.,École Centrale Lyon | Botton V.,École Centrale Lyon | And 3 more authors.
International Journal of Heat and Mass Transfer | Year: 2017

We combine an effective diffusivity model with a numerical approach initially proposed by Meyer (1981) to simulate transient heat and mass transfer phenomena in a directionally solidifying Sn-Bi rod. This particularly efficient 1D numerical model is light enough to be used within the frame of optimization methods at reasonable numerical cost. This approach is tested against reference in situ measurements obtained under microgravity conditions during the Mephisto program. We simulate the final homogenization transient of several experimental runs with different pulling velocities. The solid/liquid interface temperature evolution with time is extracted from the simulations and compared with that obtained by Seebeck in line measurements. After optimization of the model the observed discrepancy between the simulated and measured data is less than 1.5%. This validates both the proposed very efficient 1D numerical approach and the consistency of the set of thermophysical parameters values for dilute Sn-Bi alloys. © 2017 Elsevier Ltd


Barbey C.,Telespazio France | Helbert J.,Telespazio France | Jaen A.,Telespazio France | Pagot E.,Telespazio France | And 5 more authors.
Revue Francaise de Photogrammetrie et de Teledetection | Year: 2014

A comparative study between Pléiades and UAV images has been conducted for precision viticulture applications in the Aquitaine region over Buzet vineyard and two Bordeaux domains. This study has shown a good agreement between the results obtained from the different sensors, both for the characterisation of the vine plots and for the vineyard vigour assessment. Especially local vineyard heterogeneities and variabilities can be demonstrated on Pléiades imagery, which is consequently of interest for the characterisation of vineyards at regional scale. However detection of small structures is limited by Pléiades spatial resolution especially where the vine row distance is narrow (less than 2 metres). Use of alternate technologies with better spatial resolution such as Unmanned Aerial Vehicles (UAV) is relevant for more accurate plot parameter characterisations.


Guyon D.,French National Institute for Agricultural Research | Laventure S.,French National Institute for Agricultural Research | Belouard T.,IGN | Samalens J.-C.,Telespazio France | Wigneron J.-P.,French National Institute for Agricultural Research
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2015

The availability of Landsat data (Landsat 4, 5, 7 and 8) from ∼30 years makes it possible to analyze the forest long term dynamics at high resolution (30m). The performances of the Landsat time-series have been already demonstrated for mapping and monitoring the annual clear-cuts and the storm damage in the Landes Forest, that covers ∼1 million ha in southwestern France and that is heavily managed with even-aged stands with rather short rotations after clear-cut harvesting. Our objectives aimed at improving, automating, and enriching these previous methods. This was to operationally produce over the whole Landes Forest not only (1) the annual maps of clear-cutting from 1984 up the current year but also (2) the map of the current age that was derived from the forest change detected every year since 1984. The developed methodology used the time-series of surface reflectance and cloud mask provided for Landsat by USGS and sought to cope the possible absence of cloud-free image during the interest season or the numerous missing data in Landsat 7 images after 2002. The retrospective processing of the Landsat time-series from 1984 to 2014 made it possible the prediction of actual current age with a satisfactory accuracy. © 2015 IEEE.


Pinori S.,Serco | Cotton D.,SATOC | Louis J.,Telespazio France | Talone M.,Serco | Femenias P.,Earth Observation Directorate
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

ESA declared the end of the EnviSat mission on 9th May 2012, after 10 years of life (doubling the initial expected 5 years of operations). Monitoring of Near Real Time (NRT) data started in 2003 to assess the quality of measurement and calibration of the EnviSat Radar Altimeter instrument. Since then, NRT data has been stored to build a comprehensive database of altimeter parameters that can be now used not only to assess the instrument calibration and the processing data quality, but also as a starting point for defining specific performance objectives for NRT data for future altimeter missions. © 2012 IEEE.

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