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Computing singular and near-singular integrals over curved boundary elements: The strongly singular case
No full textInternational audienc
Construction de conditions transparentes pour les guides d'ondes électromagnétiques.
No full textPrésentation lors d'une journée de jeunes chercheursInternational audienceWe are interested in the numerical resolution of diffraction problems in closed electromagnetic waveguides by means of finite elements methods. To proceed, we need to truncate the domain and design adapted transparent conditions on the artificial boundary to avoid spurious reflections.When the guide is homogeneous in the transverse section, this can be done by writing an Electric-to-Magnetic condition based on a modal decomposition of the field. The latter takes a rather simple form thanks to the orthogonality of transverse modes.For guides that are heterogeneous in the transverse section, the transverse modes are no longer orthogonal but satisfy bi-orthogonality relations linked to the Poynting energy flux. Modal decompositions are more delicate to derive and it may happen that certain modes have phase and group velocities of different sign, which prevents the use of Perfectly Matched Layers.Adapting techniques already developed in elasticity, we derive a new transparent condition based on a Poynting-to-Magnetic operator with overlap.To illustrate the method, we present numerical results obtained with Nédélec finite elements using the XLiFE++ library.Nous nous intéressons à la résolution numérique des problèmes de diffraction dans les guides d'ondes électromagnétiques fermés par des méthodes d'éléments finis. Pour ce faire, nous devons tronquer le domaine et concevoir des conditions de transparence adaptées sur la frontière artificielle afin d'éviter les réflexions parasites.Lorsque le guide est homogène en section transversale, cela peut être réalisé en écrivant une condition électrique-magnétique basée sur une décomposition modale du champ. Cette dernière prend une forme relativement simple grâce à l'orthogonalité des modes transversaux.Pour les guides hétérogènes en section transversale, les modes transversaux ne sont plus orthogonaux mais satisfont à des relations de bi-orthogonalité liées au flux d'énergie de Poynting. Les décompositions modales sont plus délicates à dériver et il peut arriver que certains modes aient des vitesses de phase et de groupe de signes différents, ce qui empêche l'utilisation de couches parfaitement appariées.En adaptant des techniques déjà développées en élasticité, nous dérivons une nouvelle condition de transparence basée sur un opérateur de Poynting-magnétique avec recouvrement.Pour illustrer la méthode, nous présentons des résultats numériques obtenus avec des éléments finis Nédélec en utilisant la bibliothèque XLiFE++
A viscoelastic flow model of maxwell-type with a symmetric-hyperbolic formulation
No full textInternational audienceMaxwell models for viscoelastic flows are famous for their potential to unify elastic motions of solids with viscous motions of liquids in the continuum mechanics perspective. But the usual Maxwell models allow one to define well motions mostly for one-dimensional flows only. To define unequivocal multi-dimensional viscoelastic flows (as solutions to well-posed initial-value problems) we advocated in [ESAIM:M2AN 55 (2021) 807-831] an upper-convected Maxwell model for compressible flows with a symmetrichyperbolic formulation. Here, that model is derived again, with new details
What metadata should be used to create a database for ecological restoration monitoring data ?
No full textInternational audienceThe erosion of biodiversity is unprecedented, and one of the ways of mitigating it is to initiate ecological restoration actions. The effectiveness of these actions, often carried out as part of voluntary initiatives or in response to regulatory requirements, is best assessed on the basis of ecological monitoring data. However, attempts to provide feedback from these data are coming up against difficulties throughout the world, making it impossible to distinguish natural changes in the environment from changes linked to fluctuations of the conditions of acquisition of the data. Part of the problem is related to data banking. Once the monitoring data has been acquired, it is stored in a database. The managers responsible for monitoring generally have their own databases built on the models of national and international databases which have a data and/or metadata standard. Metadata, which provides contextual information on data acquisition and compilation, is essential for analysing the data and taking into account any biases in acquisition. A descriptive analysis of 3 reference (national and international) data and metadata standards was carried out: DarwinCore for the GBIF database, Ecological Metadata Language (EML) for scientific databases and the SINP standard for the GeoNature tool; we showed that (i) these standards are generalist standards used to describe broad-spectrum biological and ecological data, (ii) these standards are notcalibrated for the specific case of ecological monitoring data and, (iii) they have insuficient fields for a detailed description of ecological monitoring data. We suggest a list of descriptive information essential to the ecological monitoring database in the case of ecological restoration. This information specifically targets the data acquisition conditions (meteorology, observer detection capacity, protocol application conditions, etc.)
Effects of thermal ageing and ion irradiation on intergranular P segregation in low alloy steel welds
No full textInternational audienceQuantitative study of solute segregation phenomenon is crucial in material science. In the present study, the influence of thermal ageing and ion irradiation (both at 400 °C) on intergranular P segregation behaviour was studied by a correlative electron backscattering diffraction (EBSD)/transmission kikuchi diffraction (TKD)/atom probe tomography (APT) methodology. The co-segregation of P, C, Si, Mn, Ni, Cr and Mo appears at grain boundaries (GBs). After both thermal ageing and ion irradiation, there is an increased P segregation for all the detected GB types. The radiation induced/enhanced solute diffusion and segregation mechanisms were also discussed based on thermodynamic and kinetic predictions. The ternary Fe-P-C model overestimates P segregation level in a multicomponent system
Interpretable seasonal multisite hidden Markov model for stochastic rain generation in France
No full texthttps://ascmo.copernicus.org/articles/11/159/2025/International audienceWe present a lightweight stochastic weather generator (SWG) based on a multisite hidden Markov model (HMM) trained on a large area with French weather station data. Our model captures spatiotemporal precipitation patterns with a strong emphasis on seasonality and the accurate reproduction of dry and wet spell distributions. The hidden states serve as interpretable large-scale weather regimes, learned directly from the data without requiring exogenous inputs. Compared to existing approaches, it offers a robust balance between interpretability and performance, particularly for extremes. The model architecture enables seamless integration of additional weather variables. Finally, we demonstrate its application to future climate scenarios, highlighting how parameter evolution and extreme event distributions can be analyzed in a changing climate
Capitalization of energy labels on the French housing market
No full textThe building sector in France accounts for nearly a third of national emissions and energy consumption, necessitating energy retrofits and renovations to align with the government's emission reduction targets. Energy Performance Certificates (EPCs), play crucial roles in guiding this transformation. This paper explores the market capitalization of home energy labels in mainland France. Including spatial and dynamism heterogeneity and using public data on energy efficiency and property transfers, the results show that top ranked dwellings have an average 14\% significant premium compared to middle rank ones. The bottom ranked houses are priced 6\% lower than middle rank ones. In the case of apartments however, the results for bottom ranks are mitigated and un-significant in most cases. The premium seems to be higher in magnitude in bigger and more dynamic cities. Overall, the results may suggest that more specific data at a thin granularity may be required in order to increase the quality of prediction, especially in capturing heterogeneity
Hardware trojan detection based on microarchitectural signals analysis
No full textInternational audienceCertification companies rigorously inspect industrial electronic devices for safety and security reasons. In particular, detecting hardware trojans is a relevant challenge as they could be really stealthy. For that purpose, runtime monitoring is a relevant line of defense. Detection modules can be designed, based on behavorial models or attack signatures, in order to detect hardware Trojans that could be maliciously integrated into hardware components. The detection strategy consists, at the micro-architectural level, to select and analyze relevant signals whose values may betray the presence of the Trojans. This presentation describes some current research works aiming at implementing such a detection strategy on industrial FPGAs
Avis de l'Anses relatif à l’analyse des options de gestion réglementaires du disulfure de carbone (n°CAS : 75-15-0) dans le cadre de la réglementation REACH
No full textEn application des protocoles d’accord du 28 juillet 2017 et du 7 juin 2022 relatifs à l’organisation de l’Anses et des ministères de tutelle pour la mise en œuvre des Règlements REACh et CLP, un programme de travail annuel est établi entre l’Anses et les ministères de tutelle. Au sein de ce programme de travail, l’Anses identifie des substances chimiques pour lesquelles des risques pour la santé humaine et/ou l’environnement sont observés et analyse les options de gestion des risques règlementaires (Regulatory Management Option Analysis ou RMOA) afin d’apporter une aide à la décision aux ministères sur la /les mesure(s) de gestion des risques la/les plus appropriée(s) à adopter. Au cas par cas, elle approfondit dans le cadre du RMOA certains champs d’évaluation des dangers et des risques.Le programme de travail 2022 comportait la réalisation d’une analyse des options de gestion règlementaires concernant le disulfure de carbone (N° CAS : 75-15-0). Le choix de cette substance fait suite aux conclusions de l’Anses dans le cadre du règlement REACh (Anses, 2021 ; 2022). Les RMOA sont réalisés selon le format standard européen et comportent les informations suivantes :- les éléments de contexte relatifs aux informations disponibles et à l’encadrement règlementaire existant des substances ;- les informations disponibles sur les dangers et les usages des substances, les tonnages, les risques pour la santé humaine ou l’environnement, les cas d’usages susceptibles d’entraîner des effets néfastes sur la santé et/ou l’environnement, etc…, en fonction des problématiques couvertes dans le RMOA ;- une justification de la nécessité de la mise en œuvre de mesures de gestion du risque au niveau européen ;- l’identification des différentes options de gestion du risque disponibles dans le cadre du règlement REACh, du règlement CLP, ou s’appuyant sur d’autres outils législatifs et réglementations sectorielles existants en fonction des usages identifiés de ces substance
A Survey on IoT Programming Platforms: A Business-Domain Experts Perspective
No full textInternational audienceThe vast growth and digitalization potential offered by the Internet of Things (IoT) is hindered by substantial barriers in accessibility, interoperability, and complexity, mainly affecting small organizations and non-technical entities. This survey paper provides a detailed overview of the landscape of IoT programming platforms, focusing specifically on the development support they offer for varying end-user profiles, ranging from developers with IoT expertise to business experts willing to take advantage of IoT solutions to automate their organization processes. The survey examines a range of IoT platforms, classified according to their programming approach between general-purpose programming solutions, model-driven programming, mashups and end-user programming. Necessary IoT and programming backgrounds are described to empower non-technical readers with a comprehensive field summary. In addition, the paper compares the features of the most representative platforms and provides decision insights and guidelines to support end-users in selecting appropriate IoT platforms for their use cases. This work contributes to narrowing the knowledge gap between IoT specialists and end users, breaking accessibility barriers and further promoting the integration of IoT technologies in various domains