Evaluating performance of individual features of WiMAX technology is a topic of widespread discussion. Currently, there is no quantitative way of measuring WiMAX technology so that wireless operators can meet their de...Evaluating performance of individual features of WiMAX technology is a topic of widespread discussion. Currently, there is no quantitative way of measuring WiMAX technology so that wireless operators can meet their design objectives. This paper outlines a set of design criteria for WiMAX and provides a decision-making aid that ranks the importance of criteria using Analytic Hierarchy Process (AHP). This ranking should sufficiently reflect market expectations of the relative importance of various design criteria. A model integrating AHP priorities with enhanced Data Envelopment Analysis (DEA) is the basis for formulating a technological value in simple, comparable format. A case study is provided to show how this technological value is used to evaluate a three year network deployment plan. In the future, this model could be extended to WiMAX equipment suppliers for the purpose of validating performance targets of individual criteria, and enhancing supplier roadmaps for future network development.展开更多
Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space,it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer ...Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space,it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer radiation belt electron fluxes.In the present study,we develop a forecast model of radiation belt electron fluxes based on the data assimilation method,in terms of Van Allen Probe measurements combined with three-dimensional radiation belt numerical simulations.Our forecast model can cover the entire outer radiation belt with a high temporal resolution(1 hour)and a spatial resolution of 0.25 L over a wide range of both electron energy(0.1-5.0 MeV)and pitch angle(5°-90°).On the basis of this model,we forecast hourly electron fluxes for the next 1,2,and 3 days during an intense geomagnetic storm and evaluate the corresponding prediction performance.Our model can reasonably predict the stormtime evolution of radiation belt electrons with high prediction efficiency(up to~0.8-1).The best prediction performance is found for~0.3-3 MeV electrons at L=~3.25-4.5,which extends to higher L and lower energies with increasing pitch angle.Our results demonstrate that the forecast model developed can be a powerful tool to predict the spatiotemporal changes in outer radiation belt electron fluxes,and the model has both scientific significance and practical implications.展开更多
The study focuses on the research performance of Double First-Class(DFC)universities in China.A theoretical framework based on economic theory and the Analytic Hierarchy Process(AHP)method for a novel evaluation model...The study focuses on the research performance of Double First-Class(DFC)universities in China.A theoretical framework based on economic theory and the Analytic Hierarchy Process(AHP)method for a novel evaluation model is proposed.The model is performed on a sample of 41 participant DFC universities in China.Using data collected from these universities,it was found that there is no consistency between performance ranking,input ranking,and output ranking,with the best ranked universities far from the most efficient.These findings provide empirical evidence of DFC universities’research performance situation and suggest strategies that the government can use to propel their sustainable development.展开更多
An extreme and persistent heat wave event hit Missouri in summer 2012.Current operational forecast models failed to predict such an event at a long lead.The objective of the current study is to simulate this extreme e...An extreme and persistent heat wave event hit Missouri in summer 2012.Current operational forecast models failed to predict such an event at a long lead.The objective of the current study is to simulate this extreme event using a high-resolution Weather Research and Forecasting(WRF)model with eight combined physical(including longwave/shortwave radiation,microphysics,and planetary boundary layer)parameterization packages.Integrated for one month,the model successfully simulates the spatial pattern and temporal evolution of surface air temperature,compared to in-situ observations.The interesting feature is an oscillatory development of the surface air temperature,with a pronounced synoptic timescale.Such a temperature evolution is consistent with the local zonal wind fluctuation,implying the important role of anomalous temperature advection.An overall skill score that combines the performance of 2-m air temperature,relative humidity,and precipitation fields is defined.The result shows that the combination of Thompson,Rapid Radiative Transfer Model for GCMs(RRTMG),and Mellor–Yamada–Nakanishi–Niino level-3(MYNN3)schemes presents the best WRF simulation.A further analysis of this best simulation shows that the model successfully reproduces the urban heat island(UHI)effect in the Kansas City Metropolitan Area with realistic diurnal variation of 2-m air temperature in the urban and nonurban areas with a larger UHI effect at nighttime.展开更多
文摘Evaluating performance of individual features of WiMAX technology is a topic of widespread discussion. Currently, there is no quantitative way of measuring WiMAX technology so that wireless operators can meet their design objectives. This paper outlines a set of design criteria for WiMAX and provides a decision-making aid that ranks the importance of criteria using Analytic Hierarchy Process (AHP). This ranking should sufficiently reflect market expectations of the relative importance of various design criteria. A model integrating AHP priorities with enhanced Data Envelopment Analysis (DEA) is the basis for formulating a technological value in simple, comparable format. A case study is provided to show how this technological value is used to evaluate a three year network deployment plan. In the future, this model could be extended to WiMAX equipment suppliers for the purpose of validating performance targets of individual criteria, and enhancing supplier roadmaps for future network development.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42025404, 42188101, and 42241143)the National Key R&D Program of China (Grant Nos. 2022YFF0503700 and 2022YFF0503900)+1 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the Fundamental Research Funds for the Central Universities (Grant No. 2042022kf1012)
文摘Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space,it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer radiation belt electron fluxes.In the present study,we develop a forecast model of radiation belt electron fluxes based on the data assimilation method,in terms of Van Allen Probe measurements combined with three-dimensional radiation belt numerical simulations.Our forecast model can cover the entire outer radiation belt with a high temporal resolution(1 hour)and a spatial resolution of 0.25 L over a wide range of both electron energy(0.1-5.0 MeV)and pitch angle(5°-90°).On the basis of this model,we forecast hourly electron fluxes for the next 1,2,and 3 days during an intense geomagnetic storm and evaluate the corresponding prediction performance.Our model can reasonably predict the stormtime evolution of radiation belt electrons with high prediction efficiency(up to~0.8-1).The best prediction performance is found for~0.3-3 MeV electrons at L=~3.25-4.5,which extends to higher L and lower energies with increasing pitch angle.Our results demonstrate that the forecast model developed can be a powerful tool to predict the spatiotemporal changes in outer radiation belt electron fluxes,and the model has both scientific significance and practical implications.
文摘The study focuses on the research performance of Double First-Class(DFC)universities in China.A theoretical framework based on economic theory and the Analytic Hierarchy Process(AHP)method for a novel evaluation model is proposed.The model is performed on a sample of 41 participant DFC universities in China.Using data collected from these universities,it was found that there is no consistency between performance ranking,input ranking,and output ranking,with the best ranked universities far from the most efficient.These findings provide empirical evidence of DFC universities’research performance situation and suggest strategies that the government can use to propel their sustainable development.
基金Supported by the National Natural Science Foundation of China(42088101)US National Oceanic and Atmospheric Administration(NA18OAR4310298)+2 种基金US National Science Foundation(IIA-1355406)China Scholarship Council(N201808320274)Postgraduate Research and Practice Innovation Program of Jiangsu Province of China(KYCX17_0874).
文摘An extreme and persistent heat wave event hit Missouri in summer 2012.Current operational forecast models failed to predict such an event at a long lead.The objective of the current study is to simulate this extreme event using a high-resolution Weather Research and Forecasting(WRF)model with eight combined physical(including longwave/shortwave radiation,microphysics,and planetary boundary layer)parameterization packages.Integrated for one month,the model successfully simulates the spatial pattern and temporal evolution of surface air temperature,compared to in-situ observations.The interesting feature is an oscillatory development of the surface air temperature,with a pronounced synoptic timescale.Such a temperature evolution is consistent with the local zonal wind fluctuation,implying the important role of anomalous temperature advection.An overall skill score that combines the performance of 2-m air temperature,relative humidity,and precipitation fields is defined.The result shows that the combination of Thompson,Rapid Radiative Transfer Model for GCMs(RRTMG),and Mellor–Yamada–Nakanishi–Niino level-3(MYNN3)schemes presents the best WRF simulation.A further analysis of this best simulation shows that the model successfully reproduces the urban heat island(UHI)effect in the Kansas City Metropolitan Area with realistic diurnal variation of 2-m air temperature in the urban and nonurban areas with a larger UHI effect at nighttime.