66 research outputs found
Highly-parallelized simulation of a pixelated LArTPC on a GPU
The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype
Utilisation d'une serie chronologique d'images Spot pour l'etude de l'occupation du sol et le suivi des cultures dans la basse vallee du Rhone. Rapport intermediaire. Mars 1991
Crop-system characterization by multitemporal SPOT data in the south-east of France
International audienc
Crop-system characterization by multitemporal SPOT data in the south-east of France
International audienc
Utilisation d'images thermiques NOAA pour estimer l'evapotranspiration a large echelle. Application a la detection des effets de secheresse en France de 1988 a 1990
National audienc
Analyse des secheresses de 1988 a 1990 en France a partir de l'analyse combinee de donnees satellitaires NOAA-AVHRR et d'un modele agrometeorologique
National audienceThe study reported here aimed at proposing an operational methodology to estimate actual evaporation on a large scale, using AVHRR images of the NOAA satellite and an agrometeorological model. The method was applied to detect drought effects for 3 yr (1988-1989-1990) over all of France. For each year, 48 cloud-free images were selected on a 5-d basis. Surface temperatures obtained from AVHRR images were combined with the output data of an agrometeorological model using ground data from 20 stations. The simplified relationship, based on an energy budget relating midday surface-air temperature difference to daily evaporation and net radiation was used for this study. A new local splitwindow method was applied to the images in order to get a better accuracy of surface temperature. Analysis of the cumulative surface-air temperature difference revealed a regional climatic effect. Evaporation maps provided a global evaluation of droughts in all of France for the 3 yr studied.Les satellites mĂ©tĂ©orologiques ont Ă©tĂ© largement utilisĂ©s ces derniĂšres annĂ©es pour le suivi de la vĂ©gĂ©tation, principalement en utilisant lâindice de vĂ©gĂ©tation. Les donnĂ©es thermiques apportent une information complĂ©mentaire sur les conditions hydriques des cultures. La tempĂ©rature de surface est en effet reliĂ©e indirectement Ă lâĂ©vapotranspiration. Lâobjectif de cette Ă©tude est de proposer une mĂ©thodologie opĂ©rationnelle pour estimer lâĂ©vapotranspiration Ă large Ă©chelle, en utilisant de façon combinĂ©e des images AVHRR composites de 5j des satellites NOAA et un modĂšle agromĂ©tĂ©orologique Magret. La relation simplifiĂ©e basĂ©e sur le bilan dâĂ©nergie, qui relie de façon linĂ©aire lâĂ©vaporation au rayonnement net et Ă la diffĂ©rence entre la tempĂ©rature de surface et celle de lâair, a Ă©tĂ© utilisĂ©e. Les tempĂ©ratures de surface sont dĂ©duites des mesures satellitaires Ă lâaide dâune mĂ©thode multispectrale ("split-window") qui a Ă©tĂ© amĂ©liorĂ©e pour application aux couverts vĂ©gĂ©taux. La mĂ©thode proposĂ©e a Ă©tĂ© appliquĂ©e Ă lâĂ©chelle de la France afin de dĂ©tecter les effets des sĂ©cheresses de 1988 Ă 1990. Il est dĂ©montrĂ© que les diffĂ©rences de tempĂ©ratures entre la surface et lâair, cumulĂ©es dans le temps sont significatives des stress hydriques subis par les cultures et permettent de distinguer les variations climatiques rĂ©gionales. Lâanalyse des cartes dâĂ©vaporation permet une Ă©valuation globale des sĂ©cheresses en France au cours des derniĂšres annĂ©es
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