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Simulation des phases transitoires d'un échangeur de chaleur à l'aide d'un modèle d'ordre réduit paramétrique non intrusif
No full textInternational audienceSimulation des phases transitoires d'un échangeur de chaleur à l'aide d'un modèle d'ordre réduit paramétrique non intrusi
Hydrogen–vacancy effects on the elastic and plastic behaviour of Ni<100> probed by nanoindentation
No full textInternational audienc
Multidisciplinary End-to-End Document-Level Relation Extraction from Scientific Literature
No full textInternational audienceThe increasing impact of global change on coastal areas necessitates effective collaboration among stakeholders to develop sound environmental protection policies. However, the vast number of scientific publications and the interdisciplinary nature of the field make it challenging to accurately identify and extract relevant information. Current methods for analyzing coastal region literature are limited in handling complex document-level relations, impeding the development of comprehensive Knowledge Bases (KBs) essential for informed decision-making. Therefore, we introduce CoastRED, a corpus of 416 scientific abstracts focused on coastal regions, designed for interdisciplinary end-to-end Document-level Relation Extraction (DocRE), leveraging the ARDI framework(Actors, Resources, Dynamics, and Interactions) to automatically identify key entities and their roles in coastal systems. We present DUNJERE—an end-to-end model integrating Mention Detection, Coreference Resolution, Entity Typing, and Relation Extraction. Based on a U-Net architecture, DUNJERE approaches Relation Extraction as a semantic segmentation task, enhancing its performance in an end-to-end setting. Evaluations on the DocRED and ReDocRED datasets demonstrate state-of-the-art performance, while experiments on CoastRED highlight its potential to advance coastal system research by providing a robust tool for document analysis and KB construction
Experimental Investigation of the Entrainment Mechanism in Circular and Lobed Hemispherical Jets
No full textInternational audienceBetter mixing in the near-field region of jets with their surrounding fluid is of high interest for several industrial applications. Passive control that involves jet geometry modifications as compared to the traditional circular design is used in the present work. An analysis of the entrainment mechanism in the near jet-exit field is proposed for innovative hemispherical nozzles (circular and six-lobed). High-speed Time-Resolved Particle Image Velocimetry (TR-PIV) measurements are used to experimentally characterize the entrainment mechanism in these jets. The distributions of mean entrainment rates, shear layer growth, and momentum flux are investigated along the longitudinal direction within the near-field region of both circular and lobed hemispherical jets. Significant entrainment enhancement is found using the hemispherical geometry as a passive-control method. By comparing both investigated hemispherical nozzle geometries, it has been demonstrated that the lobed nozzle provides higher mixing rates compared to the circular jet. This enhancement in mixing can be attributed to the stronger streamwise vortex structures generated by the lobed nozzle geometry, which promote increased entrainment of the surrounding fluid
Mercury contamination in gull chicks raised in natural vs. urban habitats
No full textInternational audienceAnthropogenic activities have increased pressure on marine ecosystems through the continuous overflow of pollutants like mercury (Hg). Seabirds, particularly chicks, serve as effective local bioindicators of marine ecosystem health. This study assessed the influence of trophic ecology (inferred from δ13C and δ15N values) and colony location on Hg concentrations in the blood of yellow-legged (YLG, Larus michahellis) and Audouin’s (AG, Ichthyaetus audouinii) gull chicks raised in natural (YLG, AG) vs. urban habitats (YLG). We report the highest blood Hg concentrations ever documented in chicks of these species raised in natural habitats (range: AG, 0.59–4.19 μg g-1 dw; YLG, 0.74–2.82 μg g-1 dw), while urban-raised YLG chicks exhibited up to 2-fold lower Hg concentrations (range: YLG, 0.22–1.23 μg g-1 dw). Interestingly, a positive association between trophic position (reflected by δ15N) and Hg concentrations was observed in urban YLG chicks but not in chicks raised in natural habitats. On the other hand, body mass was negatively associated to blood Hg concentrations in gull chicks raised in natural colonies. Overall, these results highlight the roles of the ecological context, trophic position, and body mass increase along the nestling period on driving Hg exposure in seabird chicks. We stress for further baseline contaminant studies and for more research on how these Hg concentrations could impact the physiology and development of chicks, despite the current Hg concentrations pose an apparent low risk
Optimal control for lake eutrophication: A Dirichlet boundary control problem
No full textInternational audienceAnthropogenic activities are constantly growing and affect the water quality resources.One of consequences in lakes is the accumulation of nutrients (from watersheds activities), asphosphorus, which implies a cyanobacteria development and thus a perturbation of theecosystem and a risk for human and animal health: it is called eutrophication.We present a Dirichlet boundary control problem for the lake eutrophication, where we lookfor a trade-off between the benefits linked with the water contamination and the damages forthe lake users. We consider the control as the input area of phosphorus from the watershedinto the lake, which is only defined on the lake shore. The state problem is given by couplednonlinear partial differential equations modeling the cyanobacteria concentration and thephosphorus stock dynamics.We generally use a lifting of the control from the boundary into the whole domain for treatedthis class of control problem. We discuss the originality of the model and detail the shifting ofthe control. The well-posedness of the state problem and the existence of a global solution forthe optimal control problem are proved
Diet of two mediterranean shearwaters revealed by DNA metabarcoding
No full textInternational audienceInformation on seabird diet is key to understanding their ecological role in the marine food web. The Mediterranean Sea is a biodiversity hotspot that is experiencing a series of growing threats, including overfishing and climate change. The Scopoli’s ( Calonectris diomedea ) and Yelkouan shearwaters ( Puffinus yelkouan ), two marine predators in the region, are expected to have a piscivorous diet and exploit fishery discards, but their exact reliance on different resources is still unclear. We sampled four populations in the central Mediterranean Sea and used a combination of DNA metabarcoding and stable isotopes to compare their diets and assess trophic niches. We found prey items from 38 families belonging to 21 orders. Clupeiformes and Perciformes were the main prey groups identified in both shearwater species. In fact, diet composition largely overlapped and differed by only 3% variation in the diet consumed at order level and 16% at genus level, despite sampling different populations. The results suggest high overlap of dietary and isotopic niches, while Yelkouan shearwaters occupied a wider niche space overall. Certain taxa were potentially derived from discards but are also available naturally as juvenile fish or in foraging associations with marine megafauna such as predatory fish and turtles. These findings highlight the strong dietary overlap and ecological similarities between Scopoli’s and Yelkouan shearwaters, emphasising the importance of understanding their foraging dynamics in the context of resource competition and the increasing pressures on Mediterranean marine ecosystems
Rapport de droit comparé des législations relatives à la technologie Blockchain
No full textThis report presents an analysis of legislation relating to blockchain technology in the various areas affected by the phenomenon of distributed ledgers, including digital assets or crypto-assets, aspects relating to records and land registries, contractualisation on blockchain, currency law, anti-money laundering law and security law. The legal analysis covers all legal systems as well as the normative production of coordinating institutions (UNIDROIT, IOSCO). In the case of the United States, it covers both federal and state legislation. The purpose of the report is to provide an overall analysis of the movement towards a legal framework for the uses of blockchain and a specific analysis of this legislation, area by area.Le présent rapport rend compte de l'analyse des législations relatives à la technologie blockchain dans les divers domaines concernés par le phénomène des registres distribués, qu'il s'agisse des actifs numériques ou crypto-actifs, des aspects liés aux registres et cadastres, de la contractualisation sur blockchain, de la monnaie, la lutte contre le blanchiment d'argent ou encore du droit des sûretés. L'analyse juridique porte sur l'ensemble des systèmes juridiques ainsi que sur la production normative des institutions de coordination (UNIDROIT, OICV). Concernant les États-Unis, il porte à la fois sur la législation fédérale et sur le droit des États fédérés. L'objet du rapport est de fournir une analyse globale du mouvement d'encadrement juridique des usages de la blockchain et une analyse spécifique de ces législations, domaine par domaine
Modèle de canopée urbaine amélioré avec du lancer de rayons pour l'énergétique du bâtiment
No full textInternational audienceThe urban heat island (UHI) affects energy consumption as well as heating and cooling demand in cities. Traditional urban canopy models, such as the Urban Weather Generator (UWG), can be used to estimate the impact of the UHI on the outdoor air temperature. They simplify urban morphology by assuming idealized averaged street canyons. This limits the accuracy of solar radiation modeling, a critical component of urban energy balance. To address this, we propose integrating detailed ray tracing solar calculations into UWG, leveraging Building Information Models (BIM) to enhance geometric precision. A case study on a real neighborhood shows the impact on shortwave irradiance and air temperature predictions, with measurable but limited impacts on cooling demand.L'îlot de chaleur urbain (ICU) influe sur la consommation d'énergie ainsi que sur les besoins en chauffage et en climatisation dans les villes. Les modèles traditionnels de canopée urbaine, tels que Urban Weather Generator (UWG), peuvent être utilisés pour estimer l'impact de l'ICU sur la température de l'air extérieur. Ils simplifient la morphologie urbaine en supposant des canyons urbains idéalisés et moyennés. Cela limite la précision de la modélisation du rayonnement solaire, un élément essentiel du bilan d'énergie à la maille urbaine. Pour remédier à cela, nous proposons d'intégrer une méthode de calculs solaires détaillés par lancer de rayons dans UWG, en tirant parti d'une chaîne logicielle de BIM to BEM (BIM) pour obtenir une géométrie plus détaillée. Une étude de cas sur un quartier réel montre l'impact sur l'irradiance et la température de l'air, avec des effets mesurables mais limités sur la demande en refroidissement
Fungal-based soil food webs, not local plant nor abiotic properties, are most affected by rhizome-derived secondary metabolites of Japanese knotweed (Reynoutria japonica)
No full textInternational audiencePlant invasions are a major threat to native biodiversity. Allelopathy often plays an important role in suppressing native plants and soil organisms. Effects of these secondary metabolites on plant and soil micro-organisms are rather well known. However, the effects of allelopathy on several soil biota components, either direct or indirectly through alterations of basal resources, are still unresolved. Japanese knotweed (Reynoutria japonica), an east-Asian species, contains allelopathic secondary compounds inhibiting native plants and microbial communities in Europe. We conducted a comprehensive study to unravel the role of allelopathic compounds released by this species in shaping above (germination and growth of 9 different local species) and belowground (soil microbiota and fauna) assemblages. The experiment was designed to include or exclude secondary metabolites through activated carbon filtration of Japanese knotweed rhizome extract. After a three-month garden trial, fungal biomass remained unaffected, whereas bacterial biomass, several nematode trophic groups: bacterivores, fungivores, omnivorous-predators, and Collembola density, all declined in response to the extract. These negative effects were directly attributable to the allelopathic secondary compounds. Structural equation modeling revealed major changes in soil food-web structure, with a positive correlation between bacteria and bacterivores but a clear negative effect of allelopathy on the fungal- and Collembola-based energy channels. Interestingly, Japanese knotweed rhizome extract had little influence on local plant biomass and germination rates, indicating a decoupling between plant performance and belowground biological responses. Our study highlights the need to account for soil biota when assessing the ecological risks of invasive plants and developing management and restoration practices