Archive ouverte HAL de CY Cergy Paris Université
Not a member yet
38365 research outputs found
Sort by
Comment l'informatique interactive révolutionna l'astronomie solaire dans la décennie 1980
No full textNous présentons dans cet article comment l'arrivée de l'informatique interactive ou conversationnelle à l'observatoire de Meudon en 1981 révolutionna les traitements de données, en particulier en astronomie solaire, où la grande abondance de photons (par rapport à l'astronomie nocturne) génère un grand volume de données sous forme de séquences temporelles d'images ou de spectro images
Similitudes des discours sur la militarisation de l’IA et du cyberespace
No full textInternational audienc
Exploiting the high-resolution NIKA2 data to study the intracluster medium and dynamical state of ACT-CL J0240.0+0116
No full textInternational audienceHaving a detailed knowledge of the intracluster medium (ICM) to infer the exact cluster physics such as the cluster dynamical state is crucial for cluster-based cosmological studies. This knowledge limits the accuracy and precision of mass estimation, a key parameter for such studies. In this paper, we conduct an in-depth analysis of cluster ACT-CL J0240.0+0116 using a multi-wavelength approach, with a primary focus on high angular resolution Sunyaev-Zeldovich (SZ) thermal component observations obtained under the NIKA2 Sunyaev-Zeldovich Large Programme (LPSZ). We create composite images using NIKA2, X-ray, and optical galaxy number density maps. The results reveal distinct signs of disturbance within the cluster with the distributions of gas and member galaxies that do not overlap. We also find suggestions of an inflow of matter onto the cluster from the southwestern direction. Ultimately, we classify the cluster as disturbed, using morphological indicators derived from its SZ, X-ray, and optical image. The cluster SZ signal is also contaminated by a strong central point source. We adopt different approaches to handling this contaminant and find the estimates of our pressure and hydrostatic mass profiles robust to the point source mitigation model. The cluster hydrostatic mass is estimated at for the case where the point source was masked. These values are consistent with the mass estimated using only X-ray data and with those from previous SZ studies of the Atacama cosmology telescope (ACT) survey, with improved precision on the mass estimate. Our findings strongly suggest that ACT-CL J0240.0+0116 is a disturbed cluster system, and the detailed observations and derived values serve as a compelling case study for the capabilities of the LPSZ in mapping the cluster ICM with high precision
La Pertinence du Catalogue du Compte Personnel de Formation, vue au Prisme du Comportement des Utilisateurs
No full textInternational audienceIn France, the Personal Training Account (CPF in French) serves as the main tool for public policies aimed at financing adult training. The Mon Compte Formation (MCF) platform allows you to select the training of your choice from a particularly comprehensive catalog; it makes available a certain amount of data on its offer, data which to date remains under-exploited. In par-ticular, we present analyzes mobilizing geographical approaches, that aim to highlight the interest in methods from computer science to better understand cat-alog construction strategies, as well as the possible inadequacy of the catalogs proposed in relation to the expectations of the public, expectations that can be analyzed thanks to the logs left in research engines used within MCF.En France, le CPF sert de véhicule aux politiques publiques visant à financer la formation d'adultes. La plateforme Mon Compte Formation (MCF) permet de sélectionner la formation de son choix au sein d'un catalogue particulièrement fourni; elle met à disposition un certain nombre de données sur son offre, données qui à ce jour restent sous-exploitées. Nous présentons ici une réflexion méthodologique sur les opportunités offertes par ces traces. Elle vise à apporter un regard sociologique et géographique sur des analyses de traces réalisées par des méthodes issues de l'informatique, pour mieux contraster l'offre des catalogues de formation et les thématiques qui constituent les principaux centres d'intérêt du public de la plateforme, ceux-ci étant inférés sur la base des traces laissées via le moteur de recherche intégré au sein de MCF
The mineralogical composition of Jezero Crater Western Fan: Multigaussian modeling of Perseverance/SuperCam near-infrared observations and overview of major units
No full textInternational audienceThe analysis of the mineralogical composition of rocks within the Jezero crater, Mars, enables the reconstruction of the aqueous activity history of the site, formed during the planet’s early epochs. Numerous secondary minerals resulting from aqueous alteration, as well as some primary minerals, are observable through near-infrared reflectance spectroscopy, as performed by the IRS/SuperCam instrument onboard the Perseverance rover. The characterization of these minerals, their distribution within geological units, as well as the composition of their assemblages, is crucial for deciphering the chemical, climatic, and geological history of the Jezero crater. In order to systematically study the growing number of IR spectra collected by the instrument, we have developed an automated method for extracting the characteristics of absorption bands, based on their modeling using a combination of Gaussian curves (MultiGM). The application of this method to the entire IRS dataset reveals a significant diversity of minerals distributed throughout the rover traverse, with a near-systematic presence of phyllosilicates in bedrocks, as well as increasingly frequent occurrences of carbonates on the delta, particularly within the Margin unit. These carbonates exhibit variable 2.5 m band positions attributed to different Fe and Mg compositions. The delta front presents the sole unit generally enriched in Fe/Mg sulfates (Yori Pass/Hogwallow Flats) accompanied by occurrences of bassanite (hydrated CaSO4), whereas the presence of sulfates in other delta units and the crater floor is more sporadic and corresponds to fracture/vesicle fills. Finally, almost all the rocks analyzed with IRS/SuperCam are notably dominated by phyllosilicates signatures (Fe/Mg-smectites, serpentine), excepted for a few outcrops caping the Delta. This phyllosilicate presence witnesses the extended surficial (smectites) and hydrothermal (serpentine) aqueous alteration of Jezero’s rocks, either in situ or carried from the watershed
Symposium sur la théorie de l'équilibre général avec rationnement
No full textInternational audienceThis symposium consists of three papers. Sylvie Rivot analyses the early work ofJean-Pascal Benassy, from the thesis he defended in 1973 to a new synthesis presentedin 1982 in his book The Economics of Market Disequilibrium. Romain Plassarddiscusses the work carried out by French economists between 1977 (Laffont andGarcia) and 1993 (Artus, Avouyi-Dovi and Laffargue) to estimate econometric modelsbased on general equilibrium models with rationing. Rodolphe Dos Santos Ferreirareturns to the notion of involuntary unemployment developed by Keynes in TheGeneral Theory of Employment, Interest and Money, and proposes a reinterpretationof it by reasoning within the macroeconomic framework developed by Benassy in histhesis.Ce symposium comporte trois contributions. Sylvie Rivot analyse les premiers travaux de Jean-Pascal Bénassy de sa thèse qu’il soutint en 1973 jusqu’à une nouvelle synthèse qu’il présenta en 1982 dans son ouvrage The Economics of Market Disequilibrium. Romain Plassard traite des travaux que des économistes français réalisèrent de 1977 (Laffont et Garcia) à 1993 (Artus, Avouyi-Dovi et Laffargue) pour estimer des modèles économétriques qui s’appuyaient sur les modèles d’équilibre général avec rationnement. Rodolphe Dos Santos Ferreira revient sur la notion de chômage involontaire que développe Keynes dans The General Theory of Employment, Interest and Money et en propose une réinterprétation en raisonnant dans le schéma macroéconomique que Bénassy avait développé dans sa thèse
Deciphering the social complexity of a town through the spatial complexity of its buildings: spatial syntax applied to the Old Town of AlUla
No full textInternational audienc
Modeling and optimization of eco-friendly cellular foam geopolymer with recycled concrete and glass wastes using Box-Behnken design
No full textInternational audienc
Impact of structural inheritance and mantle potential temperature on wide asymmetric rifts
No full textInternational audienceContinental rifting, as the initial and critical phase of the Wilson Cycle, has been extensively observed and studied using 2D and 3D analogue and numerical models. These studies have effectively reproduced the characteristics of wide and narrow, symmetric and asymmetric rift structures, through horizontal multi-layered models with variable strength parameters. One prominent natural case is the South China Sea (SCS), which began its rifting and subsequent seafloor spreading at ~32 Ma. The SCS then underwent a shift in its spreading direction from a north-south to a northwest-southeast orientation at ~23 Ma. Despite resembling a typical wide rift, the SCS poses specific challenges in explaining its complex synchronous basins with detachments , non-flat Moho surface, inland hyper-thinned continental crust extending over 500 km from the continent-ocean boundary (COB), and the wide asymmetric geometry with narrow OCT (ocean continent transition) observed in the Southwest Subbasin (SWSB). Former 1D and 2D simulations have shown that wide continental rift can be produced either by rift migration, i.e. sequential basins associated with non-flat Moho, or in post orogenic context, i.e. synchronous basins form over a flat Moho due to the weakness of the lower crust. They equally fail at capturing the synchronous basins and non-flat Moho of the SCS. Considering the SCS's pre-rift fore-arc environment with thrusts featuring strong and weak crust due to tectonic events such as the Pacific subduction and the Proto South China Sea (PSCS) plate subduction, we applied 2D numerical models to replicate these features. Our models incorporate a dipping layered continental crust structure composed of strong and weak layers with varying dipping angles and thickness of lower crust, alongside temperature variations at the lithosphere-asthenosphere boundary (T_LAB). This setup successfully reproduced the margin style observed in the SWSB. Our models show four distinct rifting styles: pure single spreading center, single spreading center with hyper-thinned continental crust, single spreading center with exhumed mantle, and double spreading centers style, and three styles of Moho surface, including flat Moho, hummocky Moho and wavy Moho. Model with synchronous basins with detachments, single spreading center with inland hyper-thinned crust/exhumed mantle and hummocky Moho style fits well with observations in SWSB. This suggests that by incorporating structural, compositional and thermal variations from surrounding tectonic events, new insights into the diverse rifting features seen in SCS and a robust framework to understand wide asymmetric margins across complex geologic settings can be expected
