Search results for "Clouds"
showing 10 items of 95 documents
A study of the B and Be star population in the field of the LMC open cluster NGC 2004 with VLT-FLAMES
2005
Observations of hot stars belonging to the young cluster LMC-NGC2004 and its surrounding region have been obtained with the VLT-GIRAFFE facilities in MEDUSA mode. 25 Be stars were discovered; the proportion of Be stars compared to B-type stars is found to be of the same order in the LMC and in the Galaxy fields. 23 hot stars were discovered as spectroscopic binaries (SB1 and SB2), 5 of these are found to be eclipsing systems from the MACHO database, with periods of a few days. About 75% of the spectra in our sample are polluted by hydrogen (Halpha and Hgamma), [SII] and [NII] nebular lines. These lines are typical of HII regions. They could be associated with patchy nebulosities with a bi-m…
The ATAL within the 2017 Asian Monsoon Anticyclone: Microphysical aerosol properties derived from aircraft-borne in situ measurements
2021
The Asian summer monsoon is an effective pathway for aerosol particles and precursors from the planetary boundary layer over Central, South, and East Asia into the upper troposphere and lower stratosphere. An enhancement of aerosol particles within the Asian monsoon anticyclone (AMA), called the Asian tropopause aerosol layer (ATAL), has been observed by satellites. We discuss airborne in situ and remote sensing observations of aerosol microphysical properties conducted during the 2017 StratoClim field campaign within the AMA region. The aerosol particle measurements aboard the high-altitude research aircraft M55 Geophysica (maximum altitude reached of about 20.5 km) were conducted with a m…
Non-radial pulsations in be stars. Preparation of the corot space mission
2006
The general objective of the present work is to contribute to the knowledge of the physics of Be Stars. In particular, we are interested in studying and characterizing their pulsational properties. A very suitable tool to reach this goal is the study and analysis of photometric time series with the maximum time baseline, density and photometric accuracy.The space mission COROT scheduled to be launched in December 2006, will provide ultra high precision, relative stellar photometry for very long continuous observing runs. Up to ten stars will be observed in the seismology fields with a photometric accuracy of a few 10-4 and color information during 150 days.The observations of Be stars with …
SHOCK-CLOUD INTERACTION AND PARTICLE ACCELERATION IN THE SOUTHWESTERN LIMB OF SN 1006
2014
The supernova remnant SN 1006 is a powerful source of high-energy particles and evolves in a relatively tenuous and uniform environment despite interacting with an atomic cloud in its northwestern limb. The X-ray image of SN 1006 reveals an indentation in the southwestern part of the shock front and the H I maps show an isolated (southwestern) cloud, having the same velocity as the northwestern cloud, whose morphology fits perfectly in the indentation. We performed spatially resolved spectral analysis of a set of small regions in the southwestern nonthermal limb and studied the deep X-ray spectra obtained within the XMM-Newton SN 1006 Large Program. We also analyzed archive H I data, obtain…
Autonomic Brokerage Service for an End-to-End Cloud Networking Service Level Agreement
2014
8 pages; International audience; Today, cloud networking which is the ability to connect the user with his cloud services and to interconnect these services within an inter-cloud approach, is one of the recent research areas in the cloud computing research communities. The main drawback of cloud networking consists in the lack of Quality of Service (QoS) assurance and management in conformance with a corresponding Service Level Agreement (SLA). In this paper, we propose a framework for self-establishing an end-to-end service level agreement between a Cloud Service User (CSU) and multiple Cloud Service Providers (CSPs) in a cloud networking environment using brokerage service. We focus on Qo…
Linear relationship between effective radius and precipitation water content near the top of convective clouds
2021
Quantifying the precipitation within clouds is a crucial challenge to improve our current understanding of the Earth’s hydrological cycle. We have investigated the relationship between the effective radius of droplets and ice particles (re) and precipitation water content (PWC) measured by cloud probes near the top of growing convective cumuli. The data for this study were collected by aircraft measurements in clean and polluted conditions over the Amazon Basin and over the western tropical Atlantic in September 2014. Our results indicate a threshold of re ∼ 13 μm for warm rain initiation in convective clouds, which is in agreement with previous studies. In…
Energy Efficient Resource Allocation and User Scheduling for Collaborative Mobile Clouds with Hybrid Receivers
2014
In this paper, we study the resource allocation and user scheduling algorithm for minimizing the energy cost of data transmission in the context of OFDMA collaborative mobile cloud (CMC) with simultaneous wireless information and power transfer (SWIPT) receivers. The CMC, which consists of several collaborating MTs offers one potential solution for downlink content distribution and for the energy consumption reduction at the terminal side. Meanwhile, as RF signal can carry both information and energy simultaneously, the induced SWIPT has gained much attention for energy efficiency design of mobile nodes. Previous work on the design of CMC system mainly focused on the cloud formulation or en…
Embedded Processing and Compression of 3D Sensor Data for Large Scale Industrial Environments
2019
This paper presents a scalable embedded solution for processing and transferring 3D point cloud data. Sensors based on the time-of-flight principle generate data which are processed on a local embedded computer and compressed using an octree-based scheme. The compressed data is transferred to a central node where the individual point clouds from several nodes are decompressed and filtered based on a novel method for generating intensity values for sensors which do not natively produce such a value. The paper presents experimental results from a relatively large industrial robot cell with an approximate size of 10 m ×
The ACRIDICON-CHUVA campaign: Studying tropical deep convective clouds and precipitation over Amazonia using the new German research aircraft HALO
2016
Abstract Between 1 September and 4 October 2014, a combined airborne and ground-based measurement campaign was conducted to study tropical deep convective clouds over the Brazilian Amazon rain forest. The new German research aircraft, High Altitude and Long Range Research Aircraft (HALO), a modified Gulfstream G550, and extensive ground-based instrumentation were deployed in and near Manaus (State of Amazonas). The campaign was part of the German–Brazilian Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (Global Precipitatio…
Observed and Simulated Variability of Droplet Spectral Dispersion in Convective Clouds Over the Amazon
2021
In this study, the variability of the spectral dispersion of droplet size distributions (DSDs) in convective clouds is investigated. Analyses are based on aircraft measurements of growing cumuli near the Amazon basin, and on numerical simulations of an idealized ice‐free cumulus. In cleaner clouds, the relative dispersion ϵ, defined as the ratio of the standard deviation to the mean value of the droplet diameter, is negatively correlated with the ratio of the cloud water content (qc) to the adiabatic liquid water content (qa), while no strong correlation between ϵ and qc/qa is seen in polluted clouds. Bin microphysics numerical simulations suggest that these contrasting behaviors are associ…