The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform

Nasa - One of the best experts on this subject based on the ideXlab platform.

  • NAS technical summaries. Numerical aerodynamic simulation program, March 1992 - February 1993
    2019
    Co-Authors: Nasa
    Abstract:

    NASA created the Numerical Aerodynamic Simulation (NAS) Program in 1987 to focus resources on solving critical problems in aeroscience and related disciplines by utilizing the power of the most advanced supercomputers available. The NAS Program provides scientists with the necessary computing power to solve today's most demanding computational fluid dynamics problems and serves as a pathfinder in integrating leading-edge supercomputing technologies, thus benefitting other supercomputer centers in government and industry. The 1992-93 Operational Year concluded with 399 high-speed processor projects and 91 parallel projects representing NASA, the Department of Defense, other government agencies, private industry, and universities. This document provides a glimpse at some of the significant scientific results for the Year.

  • NAS Technical Summaries, March 1993 - February 1994
    2019
    Co-Authors: Nasa
    Abstract:

    NASA created the Numerical Aerodynamic Simulation (NAS) Program in 1987 to focus resources on solving critical problems in aeroscience and related disciplines by utilizing the power of the most advanced supercomputers available. The NAS Program provides scientists with the necessary computing power to solve today's most demanding computational fluid dynamics problems and serves as a pathfinder in integrating leading-edge supercomputing technologies, thus benefitting other supercomputer centers in government and industry. The 1993-94 Operational Year concluded with 448 high-speed processor projects and 95 parallel projects representing NASA, the Department of Defense, other government agencies, private industry, and universities. This document provides a glimpse at some of the significant scientific results for the Year.

  • NAS technical summaries: Numerical aerodynamic simulation program, March 1991 - February 1992
    2019
    Co-Authors: Nasa
    Abstract:

    NASA created the Numerical Aerodynamic Simulation (NAS) Program in 1987 to focus resources on solving critical problems in aeroscience and related disciplines by utilizing the power of the most advanced supercomputers available. The NAS Program provides scientists with the necessary computing power to solve today's most demanding computational fluid dynamics problems and serves as a pathfinder in integrating leading-edge supercomputing technologies, thus benefiting other supercomputer centers in Government and industry. This report contains selected scientific results from the 1991-92 NAS Operational Year, March 4, 1991 to March 3, 1992, which is the fifth Year of operation. During this Year, the scientific community was given access to a Cray-2 and a Cray Y-MP. The Cray-2, the first generation supercomputer, has four processors, 256 megawords of central memory, and a total sustained speed of 250 million floating point operations per second. The Cray Y-MP, the second generation supercomputer, has eight processors and a total sustained speed of one billion floating point operations per second. Additional memory was installed this Year, doubling capacity from 128 to 256 megawords of solid-state storage-device memory. Because of its higher performance, the Cray Y-MP delivered approximately 77 percent of the total number of supercomputer hours used during this Year.

Vincent-henri Peuch - One of the best experts on this subject based on the ideXlab platform.

  • Ensemble forecasts of air quality in eastern China - Part 2: Evaluation of the MarcoPolo-Panda prediction system, version 1
    Geoscientific Model Development, 2019
    Co-Authors: Anna Katinka Petersen, Guy Brasseur, Idir Bouarar, Johannes Flemming, Michael Gauss, Fei Jiang, Rostislav Kouznetsov, Richard Kranenburg, Bas Mijling, Vincent-henri Peuch
    Abstract:

    Abstract. An Operational multimodel forecasting system for air quality has been developed to provide air quality services for urban areas of China. The initial forecasting system included seven state-of-the-art computational models developed and executed in Europe and China (CHIMERE, IFS, EMEP MSC-W, WRF-Chem-MPIM, WRF-Chem-SMS, LOTOS-EUROS, and SILAMtest). Several other models joined the prediction system recently, but are not considered in the present analysis. In addition to the individual models, a simple multimodel ensemble was constructed by deriving statistical quantities such as the median and the mean of the predicted concentrations. The prediction system provides daily forecasts and observational data of surface ozone, nitrogen dioxides, and particulate matter for the 37 largest urban agglomerations in China (population higher than 3 million in 2010). These individual forecasts as well as the multimodel ensemble predictions for the next 72 h are displayed as hourly outputs on a publicly accessible web site ( http://www.marcopolo-panda.eu , last access: 27 March 2019). In this paper, the performance of the prediction system (individual models and the multimodel ensemble) for the first Operational Year (April 2016 until June 2017) has been analyzed through statistical indicators using the surface observational data reported at Chinese national monitoring stations. This evaluation aims to investigate (a) the seasonal behavior, (b) the geographical distribution, and (c) diurnal variations of the ensemble and model skills. Statistical indicators show that the ensemble product usually provides the best performance compared to the individual model forecasts. The ensemble product is robust even if occasionally some individual model results are missing. Overall, and in spite of some discrepancies, the air quality forecasting system is well suited for the prediction of air pollution events and has the ability to provide warning alerts (binary prediction) of air pollution events if bias corrections are applied to improve the ozone predictions.

  • Ensemble Forecasts of Air Quality in Eastern China – Part 2. Evaluation of the MarcoPolo-Panda Prediction System, Version 1
    2018
    Co-Authors: Anna Katinka Petersen, Idir Bouarar, Johannes Flemming, Michael Gauss, Fei Jiang, Rostislav Kouznetsov, Richard Kranenburg, Bas Mijling, Guy P. Brasseur, Vincent-henri Peuch
    Abstract:

    Abstract. An Operational multi-model forecasting system for air quality has been developed to provide air quality services for urban areas of China. The initial forecasting system included seven state-of-the-art computational models developed and executed in Europe and China (CHIMERE, IFS, EMEP MSC-W, WRF-Chem-MPIM, WRF-Chem-SMS, LOTOS-EUROS and SILAMtest). Several other models joined the prediction system recently, but are not considered in the present analysis. In addition to the individual models, a simple multi-model ensemble was constructed by deriving statistical quantities such as the median and the mean of the predicted concentrations. The prediction system provides daily forecasts and observational data of surface ozone, nitrogen dioxides and particulate matter for the 37 largest urban agglomerations in China (population higher than 3 million in 2010). These individual forecasts as well as the multi-model ensemble predictions for the next 72 hours are displayed as hourly outputs on a publicly accessible web site (www.marcopolo-panda.eu). In this paper, the performance of the predictions system (individual models and the multi-model ensemble) for the first Operational Year (April 2016 until June 2017) has been analysed through statistical indicators using the surface observational data reported at Chinese national monitoring stations. This evaluation aims to investigate a) the seasonal behavior, b) the geographical distribution and c) diurnal variations of the ensemble and model skills. Statistical indicators show that the ensemble product usually provides the best performance compared to the individual model forecasts. The ensemble product is robust even if occasionally some individual model results are missing. Overall and in spite of some discrepancies, the air quality forecasting system is well suited for the prediction of air pollution events and has the ability to provide alert warning (binary prediction) of air pollution events if bias corrections are applied to improve the ozone predictions.

Lahoucine Hanich - One of the best experts on this subject based on the ideXlab platform.

  • Assimilation of Sentinel-2 Data into a Snowpack Model in the High Atlas of Morocco
    Remote Sensing, 2018
    Co-Authors: Mohamed Wassim Baba, Simon Gascoin, Lahoucine Hanich
    Abstract:

    The snow melt from the High Atlas is a critical water resource in Morocco. In spite of its importance, monitoring the spatio-temporal evolution of key snow cover properties like the snow water equivalent remains challenging due to the lack of in situ measurements at high elevation. Since 2015, the Sentinel-2 mission provides high spatial resolution images with a 5 day revisit time, which offers new opportunities to characterize snow cover distribution in mountain regions. Here we present a new data assimilation scheme to estimate the state of the snowpack without in situ data. The model was forced using MERRA-2 data and a particle filter was developed to dynamically reduce the biases in temperature and precipitation using Sentinel-2 observations of the snow cover area. The assimilation scheme was implemented using SnowModel, a distributed energy-balance snowpack model and tested in a pilot catchment in the High Atlas. The study period covers 2015-2016 snow season which corresponds to the first Operational Year of Sentinel-2A, therefore the full revisit capacity was not yet achieved. Yet, we show that the data assimilation led to a better agreement with independent observations of the snow height at an automatic weather station and the snow cover extent from MODIS. The performance of the data assimilation scheme should benefit from the continuous improvements of MERRA-2 reanalysis and the full revisit capacity of Sentinel-2.

  • Assimilation of Sentinel-2 Data into a Snowpack Model in the High Atlas of Morocco
    2018
    Co-Authors: Mohamed Wassim Baba, Simon Gascoin, Lahoucine Hanich
    Abstract:

    The snow melt from the High Atlas is a critical water resource in Morocco. In spite of its importance, monitoring the spatio-temporal evolution of key snow cover properties like the snow water equivalent remains challenging due to the lack of in situ measurements at high elevation. Since 2015, the Sentinel-2 mission provides high spatial resolution images with a 5 day revisit time, which offers new opportunities to characterize snow cover distribution in mountain regions. Here we present a new data assimilation scheme to estimate the state of the snowpack without in situ data. The model was forced using MERRA-2 data and a particle filter was developed to dynamically reduce the biases in temperature and precipitation using Sentinel-2 observations of the snow cover area. The assimilation scheme was implemented using SnowModel, a distributed energy-balance snowpack model and tested in a pilot catchment in the High Atlas. The study period covers 2015-2016 snow season which corresponds to the first Operational Year of Sentinel-2A, therefore the full revisit capacity was not yet achieved. Yet, we show that the data assimilation led to a better agreement with independent observations of the snow height at an automatic weather station and the snow cover extent from MODIS. The performance of the data assimilation scheme should benefit from the continuous improvements in MERRA-2 reanalyses and the full revisit capacity of Sentinel-2.

D. Mayorga Gonzalez - One of the best experts on this subject based on the ideXlab platform.

  • Operability, Reliability and Economic Benefits of CSP with Thermal Energy Storage: First Year of Operation of ANDASOL 3☆
    Energy Procedia, 2014
    Co-Authors: F. Dinter, D. Mayorga Gonzalez
    Abstract:

    Abstract This current paper gives a short overview on the results of the study we have conducted to illustrate the operability and reliability properties of CSP plants based on the experience acquired during the first operation Year of the CSP generation unit with thermal energy storage (TES) Andasol 3. Andasol 3 was commissioned in autumn 2011 under the leadership of the company “Marquesado Solar S.L.” and is the third of Solar Millennium developed parabolic trough power plants. The plant is located near Guadix in Andalusia, Spain and has an installed capacity of 49.9 MWe and a thermal storage tank with a capacity of 7.5 hours at full load. The power station was designed to reach a net annual energy production of 165 GWh at typical meteorological Year conditions. Andasol 3 as well as other solar power plants with TES, are not only providers of environmentally friendly solar electricity, but also power sources with Operational capabilities that have the potential to support the continued reliability of the electric power system. Furthermore, the flexibility given by TES allows this type of plants to shift electricity generation meeting capacity needs and peak demand resulting in a rise of utility value due to increased revenues. In order to demonstrate the properties mentioned above and to present the experience gained during the first Operational Year, Andasol 3 conducted a study based on actual economic and technical data collected during the period past. Our first priority was to explore several operating modes aiming to maximize the economic benefits of the plant and to gain an experience-based foundation that contributes to further developments. For this purpose several Operational tests were conducted and anomalies owing to external and internal influence conditions were analyzed and evaluated.

Michael S. Lehv - One of the best experts on this subject based on the ideXlab platform.

  • Medicare charges and the Operational-Year coding concept.
    Journal of the American Medical Informatics Association : JAMIA, 1994
    Co-Authors: Michael S. Lehv
    Abstract:

    The introduction by the Health Care Financing Administration, in 1993, of separate conversion factors for “medical” and “surgical” services to be used in calculating Medicare charges would ordinarily necessitate the use of Year-specific software source code. By designing the system to utilize macro-substitution of the Year in the names of Current Procedural Terminology for Physicians Code databases, database fields, and system variables, it is possible to calculate Medicare charges without annually rewriting source code. Once such a system is in place, simply by changing the Operational Year, the correct data and means of computation are automatically available.