HAL: Hyper Article en Ligne
Not a member yet
3159010 research outputs found
Sort by
Characterization of the Electronic Noise in the Readout of Resistive Micromegas in the High-Angle Time Projection Chambers of the T2K Experiment
No full textInternational audienceThe two high-angle Time Projection Chambers of the T2K experiment are equipped with a new readout system based on resistive Micromegas detector technology, and utilize custom-made electronics based on AFTER chips for signal processing. This study analyzes and characterizes the electronic noise of the detector readout chain to develop a comprehensive noise model. The model enables the generation of Monte Carlo simulations to investigate systematic effects in signal processing. The analysis is based on data collected from 32 resistive Micromegas detectors, recorded without zero suppression. All detectors exhibit a quasi-identical and time-stable noise level. The developed analytical model accurately describes the observed noise, and derived Monte Carlo simulations show excellent agreement with experimental data
A new friction model for simulation, estimation and motion control
No full textInternational audienceThis paper presents a new model of friction forces intended to be used for designing motion controllers and system simulation and estimation. The model is based on physical insights and captures the behavior of friction forces with respect to the slip velocities. Compared with existent models, this model is very simple, requiring a small number of parameters to be tuned. Motivated by the nature of induced forces of friction, the behavior of friction forces has been modeled as a Steinmetz equivalent circuit, which includes particular dissipation terms. Simulated examples illustrate the effectiveness of the model in capturing the behavior of friction forces observed in nature.Cet article présente un nouveau modèle de forces de frottement destiné à être utilisé pour la conception de contrôleurs de mouvement et pour la simulation et l'estimation de systèmes. Le modèle est basé sur des connaissances physiques et capture le comportement des forces de frottement par rapport aux vitesses de glissement. Comparé aux modèles existants, ce modèle est très simple et nécessite peu de paramètres à régler. En particulier, le modèle proposé est écrit en termes de paramètres qui peuvent avoir une signification physique. Motivé par la nature des forces de frottement induites, le comportement des forces de frottement a été modélisé comme un circuit équivalent de Steinmetz, qui inclut des termes de dissipation particuliers. Des exemples simulés illustrent l'efficacité du modèle à capturer le comportement des forces de frottement observées dans la nature
L’Égypte de Nasser : classes moyennes et idéal socialiste
No full textInternational audienceCe livre est issu de la thèse de doctorat que l'autrice a soutenue en juin 2024 à Sorbonne-Université. Il présente l’histoire du concept arabe de « classe moyenne » (al-ṭabaqa al-wusṭā ou al-ṭabaqa al-mutawassiṭa) dans l’Égypte de Nasser (1952-1970). En choisissant d’analyser les connotations de ce terme et ses usages, en arabe, par les dirigeants, intellectuels et sociologues égyptiens de l’époque, ce travail fait un pas de côté vis-à-vis de l’historiographie générale qui a vu dans les deux décennies nassériennes l’époque triomphale de la « classe moyenne » tout en la définissant de l’extérieur. Il s’agit de dé-fétichiser ce syntagme dont la teneur ne cesse d’évoluer en Égypte et de rendre compte du travail de définition et de correction ainsi que de la lutte symbolique dont est issu le concept de « classe moyenne » dans les années 1950 et 1960. Outil narratif nationaliste, il devient un indicateur statistique et sociologique de développement autour duquel l’État nassérien pense son destin national. Étudier le millefeuille d’influences philosophiques et économiques occidentales autant que nationales que constitue le concept de « classe moyenne » contribue ainsi à réenvisager l’histoire de l’Égypte à l’époque de Nasser, des aspirations de ses dirigeants et de celles de sa population, à l’ère du développement
Introduction générale, in Dossier « La Cour de justice de l’Union européenne face à l’enjeu migratoire »
No full textInternational audienc
Development of the Range Counter for the COMET Phase- Experiment
No full textInternational audienceThe COMET Phase- experiment aims to evaluate the novel muon transport beamline for the muon-to-electron conversion search at J-PARC, Japan. A dedicated Range Counter (RC) was developed to measure the momentum spectrum of transported negative muons with momenta of 30--100 MeV/. The RC consists of graphite momentum degraders, a muon absorber, and plastic scintillation counters (, , and ) to detect decay-in-orbit (DIO) electrons from stopped muons. The number of muons stopped in the absorber is reconstructed from the decay time distribution. A copper absorber was selected due to the short lifetime of muonic atoms in copper, which enhances signal separation. The counters' performance was evaluated experimentally. The Counter, made of a scintillator plate, achieved a muon-trigger efficiency exceeding 99.9%. The and Counters also demonstrated high electron-detection efficiencies of %. Based on these results, simulation studies estimate the acceptance for reconstructing the number of DIO electrons from the absorber to be approximately 47% with a corresponding signal purity of 60% against muon capture-induced backgrounds
Tribulations en terre lointaine
No full textChen Quzhen 陈渠珍（1882-1952）, Jiaoye chen meng 艽野尘梦, Chongqing renmin chubanshe, 2019, 327p
The influence of the 3D Galactic gas structure on cosmic-ray transport and gamma-ray emission
No full textInternational audienceCosmic rays (CRs) play a major role in the dynamics of the interstellar medium (ISM). Their interactions and transport ionize, heat, and push the ISM thereby coupling different regions of it. The spatial distribution of CRs depends on the distribution of their sources as well as the ISM constituents they interact with, such as gas, starlight, and magnetic fields. Particularly, gas interacts closely with CRs, influencing CR fluxes and gamma -ray emission. We illustrate the influence of 3D gas structures on CR transport and gamma -ray emission. We use the PICARD code and multiple samples of recent 3D reconstructions of the HI and H Galactic gas constituents to investigate the impact on the transport of CRs and emission of gamma -rays. We find the necessary transport parameters to reproduce local measurements of CR fluxes, and see that they depend on the local distribution of gas density and structure. The distribution of CR fluxes exhibits energy-dependent structures that vary for all CR species due to their corresponding loss processes. Regions of enhanced secondary (primary) species are spatially correlated (anti-correlated) with the gas density. We observe a high sensitivity of the gamma -ray emission on the contrast of gas structures, as those determine the 3D spatial distributions of hadronic interactions and bremsstrahlung. We find that corresponding gas-induced structures in the distribution of CR electrons are also visible in Inverse Compton (IC) emission. Due to the aforementioned sensitivity, the analysis of CR data for CR sources and transport parameters requires the usage of accurate 3D gas maps
Mercury concentrations, habitat and trophic position of Antimora rostrata and Macrourus holotrachys from South Georgia (Southern Ocean)
No full textInternational audienceMercury (Hg) is a neurotoxic element that can harm marine wildlife. Hg can reach the Southern Ocean through atmospheric and oceanic currents. However, data on Hg in Southern Ocean deep-sea fishes remain scarce. Our study assessed the influence of biological and ecological factors on Hg bioaccumulation in two deep-sea species, blue antimora (Antimora rostrata) and bigeye grenadier (Macrourus holotrachys), inhabiting the South Georgia region. Specifically, we aimed to: 1) analyse the habitat and trophic position of both species; 2) understand how Hg concentrations vary between tissues (muscle, brain, liver and gills); 3) evaluate how biological (length and weight) and ecological characteristics (trophic position (δ15N) and habitat (δ13C)) influence Hg concentrations. Muscle tissue had the highest Hg concentrations in both species, while the liver in A. rostrata and gills in M. holotrachys had the lowest. Overall, A. rostrata exhibited lower Hg concentrations (51.0 ± 9.0) than M. holotrachys (62.0 ± 11.0). No significant relationships were found between Hg concentrations and length, weight nor trophic position of A. rostrata. In contrast, M. holotrachys showed a positive relationship between Hg concentrations and habitat in all tissues, whereas for length and weight this positive relationship was observed in most tissues except the brain. A. rostrata is a pelagic feeder, whereas M. holotrachys mostly feeds near the sea bottom, highlighting how feeding strategy and habitat influence Hg bioaccumulation. It also reveals unexpectedpatterns of Hg distribution among tissues, particularly in the brain, where M. holotrachys exhibited one of thehighest Hg concentrations