Search results for "Cloud"
showing 10 items of 827 documents
Milestones of complex computing facility assembling
2015
IMCS UL continues its enduring development of research e-infrastructure, participates in international projects such as GEANT, GN2, GN3, GN3+, GN4, BalticGRID, BG II and EGI-InSPIRE, has involved in CLARIN and ELIXIR ESFRI ERIC activities. Currently IMCS UL maintains Scientific Cloud unified computing facility realized as ½ PTB SAN storage (IBM DS4700 with servers); provides collocation, hosting and virtualization services. As well it operates as a node for online correlation data streaming services from Irbene radio telescope in real time, HPC resources' disposal for computing tasks, usage of Big data extracted from data storage for modeling and also for graphic data processing. In the sam…
A survey on data center network topologies
2018
Data centers are the infrastructures that support the cloud computing services. So, their topologies have an important role on controlling the performance of these services. Designing an efficient topology with a high scalability and a good network performance is one of the most important challenges in data centers. This paper surveys recent research advances linked to data center network topologies. We review some representative topologies and discuss their proprieties in details. We compare them in terms of average path length, network fault tolerance, scalability and connection pattern techniques. Springer Nature Switzerland AG 2018. Acknowledgment. This publication was made possible by …
Real-Time Human Pose Estimation from Body-Scanned Point Clouds
2015
International audience; This paper presents a novel approach to estimate the human pose from a body-scanned point cloud. To do so, a predefined skeleton model is first initialized according to both the skeleton base point and its torso limb obtained by Principal Component Analysis (PCA). Then, the body parts are iteratively clustered and the skeleton limb fitting is performed, based on Expectation Maximization (EM). The human pose is given by the location of each skeletal node in the fitted skeleton model. Experimental results show the ability of the method to estimate the human pose from multiple point cloud video sequences representing the external surface of a scanned human body; being r…
New Cloud Detection Algorithm for Multispectral and Hyperspectral Images: Application to ENVISAT/MERIS and PROBA/CHRIS Sensors
2006
This work presents a new methodology that faces the problem of accurate identification of location and abundance of clouds in multispectral images acquired by space-borne sensors working in the visible and near-infrared (VNIR) spectral range. The amount of images acquired over the globe every day by the instruments on board Earth Observation satellites makes inevitable that many of these images present cloud covers. The objective of this work is to develop and validate a method that takes advantage of the high spectral and radiometric resolution, and the specific band locations (e.g. the oxygen band) of present multispectral sensors to increase the cloud detection accuracy. Moreover, the me…
Evaluation of SLA-based decision strategies for VM scheduling in cloud data centers
2016
Service level agreements (SLAs) gain more and more importance in the area of cloud computing. An SLA is a contract between a customer and a cloud service provider (CSP) in which the CSP guarantees functional and non-functional quality of service parameters for cloud services. Since CSPs have to pay for the hardware used as well as penalties for violating SLAs, they are eager to fulfill these agreements while at the same time optimizing the utilization of their resources.In this paper we examine SLA-aware VM scheduling strategies for cloud data centers. The service level objectives considered are resource usage and availability. The sample resources are CPU and RAM. They can be overprovision…
Cloud screening and multitemporal unmixing of MERIS FR data
2007
The operational use of MERIS images can be hampered by the presence of clouds. This work presents a cloud screening algorithm that takes advantage of the high spectral and radiometric resolutions of MERIS and the specific location of some of its bands to increase the cloud detection accuracy. Moreover, the proposed algorithm provides a per-pixel probabilistic map of cloud abundance rather than a binary cloud presence flag. In order to test the proposed algorithm we propose a cloud screening validation method based on temporal series. In addition, we evaluate the impact of the cloud screening in a multitemporal unmixing application, where a temporal series of MERIS FR images acquired over Th…
Self-dressing in classical and quantum electrodynamics
2003
A short review is presented of the theory of dressed states in nonrelativistic QED, encompassing fully and partially dressed states in atomic physics. This leads to the concept of the reconstruction of the cloud of virtual photons and of self-dressing. Finally some recent results on the classical counterpart of self-dressing are discussed and a comparison is made with the QED case. Attention is drawn to open problems and future lines of research are briefly outlined.
The Reprocessed Proba-V Collection 2: Product Validation
2021
With the objective to improve data quality in terms of cloud detection, absolute radiometric calibration and atmospheric correction, the PRoject for On-Board Autonomy-Vegetation (PROBA-V) data archive (October 2013 - June 2020) will be reprocessed to Collection 2 (C2). The product validation is organized in three phases and focuses on the intercomparison with PROBA-V Collection 1 (C1), but also consistency analysis with SPOT-VGT, Sentinel-3 SYN-VGT, Terra-MODIS and METOP-AVHRR is foreseen. First preliminary results show the better performance of cloud and snow/ice masking, and indicate that statistical consistency between PROBA-V C2 and C1 are in line with expectations. PROBA-V C2 data are …
Cloud-screening algorithm for ENVISAT/MERIS multispectral images
2007
This paper presents a methodology for cloud screening of multispectral images acquired with the Medium Resolution Imaging Spectrometer (MERIS) instrument on-board the Environmental Satellite (ENVISAT). The method yields both a discrete cloud mask and a cloud-abundance product from MERIS level-lb data on a per-pixel basis. The cloud-screening method relies on the extraction of meaningful physical features (e.g., brightness and whiteness), which are combined with atmospheric-absorption features at specific MERIS-band locations (oxygen and watervapor absorptions) to increase the cloud-detection accuracy. All these features are inputs to an unsupervised classification algorithm; the cloud-proba…
Further evidence for CCN aerosol concentrations determining the height of warm rain and ice initiation in convective clouds over the Amazon basin
2017
We have investigated how aerosols affect the height above cloud base of rain and ice hydrometeor initiation and the subsequent vertical evolution of cloud droplet size and number concentrations in growing convective cumulus. For this purpose we used in situ data of hydrometeor size distributions measured with instruments mounted on HALO aircraft during the ACRIDICON–CHUVA campaign over the Amazon during September 2014. The results show that the height of rain initiation by collision and coalescence processes (Dr, in units of meters above cloud base) is linearly correlated with the number concentration of droplets (Nd in cm−3) nucleated at cloud base (Dr ≈ 5 ⋅ Nd). Additional cloud processes…