A Cognitive Vision System for Nuclear Fusion Device Monitoring

International audienceWe propose a cognitive vision-based system for the intelligent monitoring of tokamaks during plasma operation, based on multi-sensor data analysis and symbolic reasoning. The practical purpose is to detect and characterize in real time abnormal events such as hot spots measured through infrared images of the in-vessel components in order to take adequate decisions. Our system is made intelligent by the use of a priori knowledge of both contextual and perceptual information for ontology-driven event modeling and task-oriented event recognition. The system is made original by combining both physics-based and perceptual information during the recognition process. Real time reasoning is achieved thanks to task-level software optimizations. The framework is generic and can be easily adapted to different fusion device environments. This paper presents the developed system and its achievements on real data of the Tore Supra tokamak imaging system

Assessing changes in global fire regimes

PAGES, Past Global Changes, is funded by the Swiss Academy of Sciences and the Chinese Academy of Sciences and supported in kind by the University of Bern, Switzerland. Financial support was provided by the U.S. National Science Foundation award numbers 1916565, EAR-2011439, and EAR-2012123. Additional support was provided by the Utah Department of Natural Resources Watershed Restoration Initiative. SSS was supported by Brigham Young University Graduate Studies. MS was supported by National Science Centre, Poland (grant no. 2018/31/B/ST10/02498 and 2021/41/B/ST10/00060). JCA was supported by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 101026211. PF contributed within the framework of the FCT-funded project no. UIDB/04033/2020. SGAF acknowledges support from Trond Mohn Stiftelse (TMS) and University of Bergen for the startup grant ‘TMS2022STG03’. JMP participation in this research was supported by the Forest Research Centre, a research unit funded by Fundação para a Ciência e a Tecnologia I.P. (FCT), Portugal (UIDB/00239/2020). A.-LD acknowledge PAGES, PICS CNRS 06484 project, CNRS-INSU, Région Nouvelle-Aquitaine, University of Bordeaux DRI and INQUA for workshop support.Background The global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300. Results Respondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios. Conclusion The influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.Peer reviewe

Communauté légale. – Dissolution. Séparation de biens judiciaire

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Thermal Event Recognition Applied to Tokamak Protection during Plasma Operation

International audienceMagnetic confinement fusion reactors are complex devices where a large amount of energy is required to make the fusion reactions happen. In such experimental conditions, the Plasma Facing Components (PFC) are subjected to high heat fluxes. In current tokamaks like Tore Supra, infrared thermographic diagnostics based on image analysis and feedback control are used to measure and monitor the heating of the PFC during plasma operation. The system consists in detecting high increase of the IR luminance signal beyond fixed temperature thresholds for a set of predefined Regions of Interest (ROI). Consequently, this system neither takes into account the thermal objects outside of the ROI, nor the geometric information of the detected thermal object. In this paper, we propose a new vision based approach for the automatic detection of thermal events. This approach is composed of three main tasks: thermal object detection (1), classification (2), and thermal event recognition (3). We present results of our approach for the recognition of one critical thermal event and compare it with the previous system

Extended-Defect-Related Photoluminescence Line at 3.33 eV in Nanostructured ZnO Thin Films

International audienceThe 3.33 eV photoluminescence line is investigated in ZnO thin films deposited by dip coating. These films are oriented along the c-axis and exhibit basal-plane stacking faults and random grain boundaries. It is found that the relative intensity of the free exciton peak to the 3.33 eV line decreases as the nanoparticle size is reduced and that the corresponding Huang-Rhys factor is about 0.5. This reveals that excitons bound to extended defects at grain boundaries are involved. Also, post growth annealing strongly affects the photoluminescence spectra. In particular, the 3.31 eV line coming from stacking faults is enhanced at high annealing temperatur

Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

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Photoluminescence properties of ZnO nanostructures grown by chemical processes

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Végétation de la tourbière de Canroute, dans les Monts de Lacaune (Le Margnès, Tarn)

International audienceVegetation of Canroute peatland, in Lacaune hills (Le Margnès, Tarn). The Canroute peatland is the most remarkable peat-forming habitat of the Tarn French department. It houses a high plant diversity, with 9 species of Sphagnum and several rare herbs, including some with a strong oceanic affinity (notably, Carex binervis, Narthecium ossifragum and Rhynchospora alba), which distinguishes it from similar habitats of Monts de l’Espinouse and Cévennes.La tourbière de Canroute est la plus remarquable tourbière à sphaignes du département du Tarn. Elle abrite un cortège floristique riche, comportant 9 espèces de sphaignes et plusieurs herbacées rares, dont certaines avec une forte affinité océanique (en particulier, Carex binervis, Narthecium ossifragum et Rhynchospora alba), ce qui la distingue des tourbières des Monts de l’Espinouse et des Cévennes

Resolving ZnO-based coaxial core-multishell heterostructure by electrical scanning probe microscopy

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