Search results for "Models"
showing 10 items of 8211 documents
ARXPS double layers model for in-situ characterization of MOCVD nanometric films.
2006
Communication orale
Discovering human mobility from mobile data : probabilistic models and learning algorithms
2020
Smartphone usage data can be used to study human indoor and outdoor mobility. In our work, we investigate both aspects in proposing machine learning-based algorithms adapted to the different information sources that can be collected.In terms of outdoor mobility, we use the collected GPS coordinate data to discover the daily mobility patterns of the users. To this end, we propose an automatic clustering algorithm using the Dirichlet process Gaussian mixture model (DPGMM) so as to cluster the daily GPS trajectories. This clustering method is based on estimating probability densities of the trajectories, which alleviate the problems caused by the data noise.By contrast, we utilize the collecte…
Muons in air showers at the Pierre Auger Observatory
2015
We present the first hybrid measurement of the average muon number in air showers at ultrahigh energies, initiated by cosmic rays with zenith angles between 62° and 80°. The measurement is based on 174 hybrid events recorded simultaneously with the surface detector array and the fluorescence detector of the Pierre Auger Observatory. The muon number for each shower is derived by scaling a simulated reference profile of the lateral muon density distribution at the ground until it fits the data. A 1019eV shower with a zenith angle of 67°, which arrives at the surface detector array at an altitude of 1450 m above sea level, contains on average (2.68±0.04±0.48(sys))×107 muons with energies large…
Influence of vessel characteristics and atmospheric processes on the gas and particle phase of ship emission plumes: in situ measurements in the Medi…
2020
A total of 252 emission plumes of ships operating in the Mediterranean Sea and around the Arabian Peninsula were investigated using a comprehensive dataset of gas- and submicron-particle-phase properties measured during the 2-month shipborne AQABA (Air Quality and Climate Change in the Arabian Basin) field campaign in summer 2017. The post-measurement identification of the corresponding ship emission events in the measured data included the determination of the plume sources (up to 38 km away) as well as the plume ages (up to 115 min) and was based on commercially available historical records of the Automatic Identification System. The dispersion lifetime of chemically inert C…
Bend- and splitting loss of dielectric-loaded surface plasmon-polariton waveguides.
2008
International audience; The design, fabrication, characterization, and modeling of basic building blocks of plasmonic circuitry based on dielectric- loaded surface polariton waveguides, such as bends, splitters, and Mach- Zehnder interferometers are presented. The plasmonic components are realized by depositing subwavelength dielectric ridges on a smooth gold film using mass-production- compatible UV-photolithography. The near-field characterization at telecommunication wavelengths shows the strong mode confinement and low radiation and bend losses. The performance of the devices is found in good agreement with results obtained by full vectorial three-dimensional finite element simulations.…
Modelling analysis of centroid curves of olfactory habituation in humans
2020
Indexation en cours.; International audience; Previously published experiments established the time-course of olfactory habituation in humans, and extracted 3 centroid curves from clustering analysis that reflected high, middle and low habituation. The aim of the current theoretical study was to further analyse these previous experimental data by developing a mathematical modelling analysis designed for fitting the 3 curves from a general equation. After adjusting equation parameters for each curve, fitting equation outcomes on experimental data yielded high correlation coefficients of 0.9997 – 0.9995 – 0.9962, respectively. A model-based interpretation of olfactory-habituation centroid cur…
Distribution models and environmental changes : Application to echinoid faunas in the Southern Ocean and ecoregionalization
2018
Current environmental changes, which impact marine environments, cover major scientific and societal issues, especially as these environmental changes are expected to accelerate along the 21st century. Understanding and forecasting the response of marine biodiversity to these changes is a pregnant scientific issue. Biogeographic and macroecological approaches provide a scientific framework for that purpose. They allow describing and understanding species distribution patterns at large spatial scale as well as estimating their potential shift with regards to environmental change. This is particularly true in the Southern Ocean, where the effects of climate change are already occurring and wh…
Biotic control of atrazine degradation in soils: functional diversity of degradation and macrofauna effects.
2006
communication oraleFR2116communication orale
Modeling lead input and output in soils using lead isotopic geochemistry
2004
The aim of this study is to model downward migration of lead from the plow layer of an experimental site located in Versailles (about 15 km southwest of Paris, France). Since 1928, samples have been collected annually from the topsoil of three control plots maintained in bare fallow. Thirty samples from 10 different years were analyzed for their lead and scandium contents and lead isotopic compositions. The fluxes are simple because of the well-controlled experimental conditions in Versailles: only one output flux, described as a first-order differential function of the anthropogenic lead pool, was taken into account; the inputs were exclusively ascribed to atmospheric deposition. The combi…
The Urban Exposome during Pregnancy and Its Socioeconomic Determinants
2018
Background: The urban exposome is the set of environmental factors that are experienced in the outdoor urban environment and that may influence child development. Objective: The authors’ goal was to describe the urban exposome among European pregnant women and understand its socioeconomic determinants. Methods: Using geographic information systems, remote sensing and spatio-temporal modeling we estimated exposure during pregnancy to 28 environmental indicators in almost 30,000 women from six population-based birth cohorts, in nine urban areas from across Europe. Exposures included meteorological factors, air pollutants, traffic noise, traffic indicators, natural space, the built environment…