HAL Clermont Université
Not a member yet
90968 research outputs found
Sort by
Characterizing the magnetic signal generated in the magnetosphere from 1996 to 2024 using ground geomagnetic data
No full textInternational audienceThe geomagnetic field, as observed at the Earth’s surface or LEO satellite altitudes (between 300 km and 800 km), is the combination of signals generated by various internal and external sources. The internal sources are mainly associated with the liquid outer core flow, magnetized rocks in the lithosphere and induced electric currents in the crust and mantle. External sources are electric currents flowing in the ionosphere and magnetosphere. We focus on the contributions from the magnetospheric fields and describe a modeling approach in Spherical Harmonics (SH) based on magnetic observatory vector field measurements. The aim of this study is to model the magnetospheric field contributions observed during geomagnetically quiet time up to SH degree 6, with a 1-h temporal resolution for the period covering years 1996.0–2024.8. The adopted modeling approach is based on the Kalman filter and the correlation-based technique, which leads to series of hourly snapshot models together with robust error estimates. The series of models in time compare well with the global magnetospheric Ring Current index (RC). We observed and described various magnetospheric field structures, including local time asymmetries and contributions from ring and magnetotail currents. We also examined annual, semi-annual, monthly and daily variations in magnetospheric field Gauss coefficients in the Fourier domain
Flaubert et la peinture
No full text•Stéphanie Dord-Crouslé, « Flaubert et la peinture », avec Yvan Leclerc et Françoise Mobihan, dans le cadre d’une table ronde « Flaubert, à Maupassant : “dessine-moi Étretat” » organisée par les Amis de Flaubert et de Maupassant le 17/01/2026 au Musée des Beaux-arts de Lyon à l’occasion de l’exposition « Étretat, par-delà les falaises. Courbet, Monet, Matisse » (29/11/2025-01/03/2026).National audienc
Evaluating the flexural performance of bio-based concrete with different types of bio-aggregate and binder
No full textInternational audienceThis study investigates the influence of bio-aggregate type (hemp, bamboo, and reed) and binder type (CEMIV, LC3, and PNC) on the flexural performance of bio-based concrete, with the objective of identifying optimized formulations for construction applications. The term 'optimization' refers to the identification of favorable aggregate-binder combinations based on a comparative assessment of flexural strength, stiffness, deformation behavior, and cracking characteristics. Digital image correlation was employed to analyze deformation and cracking behavior. The results indicate that hemp-based concretes combined with CEMIV exhibit the highest flexural performance, benefiting from effective crack-bridging mechanisms. Reed-based concretes demonstrate a more stable and homogeneous flexural response, particularly when combined with higher-performance binders such as CEMIV and LC3. In contrast, bamboo-based concretes show pronounced interfacial debonding, especially when paired with lower-strength binders (such as PNC), leading to early strain localization. Binders with high fineness, such as PNC, promote the development of finer and more uniformly distributed cracks, despite lower global flexural performance. These findings provide fundamental insights into the intrinsic flexural behavior of bio-based concretes, indicating that the complementary combination of the dimensional stability of reed aggregates and the favorable mechanical performance of hemp shives can form a robust basis for the future development of reinforced bio-based composites, such as fabric-reinforced cementitious matrix (FRCM) systems, where optimized substrate performance is essential
Transducing Linear Decompositions of Tournaments
No full textBojańczyk, Pilipczuk, and Grohe [LICS '18] proved that for graphs of bounded linear clique-width, clique-decompositions of bounded width can be produced by a CMSO transduction. We show that in the case of tournaments, a first-order transduction suffices. This implies that the logics CMSO and existential MSO are equivalent over bounded linear clique-width tournaments
The Political Economy of Mining Rent Sharing: Is Government Effectiveness Really Costly?
No full textInternational audienceThis paper builds on the work of a previous study to modelling the political economy factors that influence government take over the lifespan of mining projects. We extend the political economy model by incorporating the opportunity costs of preferences for side payments, thereby enhancing its predictive power to explain government take. Preferences for side payments are likely to exist only in contexts where government effectiveness is limited and corruption is rampant. Our empirical evidence using data on de jure government take in copper mining projects in Africa and Latin America confirms the theoretical predictions by the revisited political economy model. Specifically, we find that government effectiveness is a key driving factor with a two‐dimensional linkage. As government effectiveness improves, countries with high level of corruption experience lower government take, while those with high transparency and strong political regimes experience higher government take
Spreading properties of the Fisher--KPP equation when the intrinsic growth rate is maximal in a moving patch of bounded size
No full textInternational audienceThis paper is concerned with spreading properties of space-time heterogeneous Fisher–KPP equations in one space dimension. We focus on the case of everywhere favorable environment with three different zones, a left half-line with slow or intermediate growth, a central patch with fast growth and a right half-line with slow or intermediate growth. The central patch moves at various speeds. The behavior of the front changes drastically depending on the speed of the central patch. Among other things, intriguing phenomena such as nonlocal pulling and locking may occur, which would make the behavior of the front further complicated. The problem we discuss here is closely related to questions in biomathematical modelling. By considering several special cases, we illustrate the remarkable diversity of possible behaviors. In particular, when the central patch has constant size and constant speed, we provide a complete set of explicit formulas for the spreading speed
Association between rheumatoid arthritis flares and joint structural changes at 24 months: using FLARE-RA questionnaire
No full textInternational audienceTo describe whether rheumatoid arthritis (RA) flares detected by the self-administered Flare Assessment in Rheumatoid Arthritis (FLARE-RA) questionnaire can predict joint structural damage progression at 2 years and to explore the association between the FLARE-RA score and RA outcome measures
