In 2010-2012 spring, atmospheric duct observation experiments were performed throughout three open cruises over the South China Sea and the Tropical Eastern Indian Ocean. The data used for ducting analysis were measur...In 2010-2012 spring, atmospheric duct observation experiments were performed throughout three open cruises over the South China Sea and the Tropical Eastern Indian Ocean. The data used for ducting analysis were measured by high resolution balloon-borne GPS radiosondes. Through data quality control and diagnostic analysis, the probability of ducting occurrence and characteristic quantities of the three typical ducts were given. The total percentage occurrence of evaporation duct, surface-based duct and elevated duct were 75.3%, 5% and 43.7%, respectively. The mean evaporation duct height was 15.3 m. The mean values of duct height, thickness and magnitude were 84.1 m, 14.9 m and 10 M-units for surfaced-based duct, and 1003.6 m, 62.2 m and 7.9 M-units for elevated duct. These preliminary statistical results can serve as a basis for future comprehensive and comparative studies of atmospheric duct for the research region.展开更多
A game model is usually decided by three factors:players,strategies and pay-off functions.It’s easier to define the players and their strategies than their pay-off functions.Mostly,the pay-off functions need to be es...A game model is usually decided by three factors:players,strategies and pay-off functions.It’s easier to define the players and their strategies than their pay-off functions.Mostly,the pay-off functions need to be estimated,and the difference estimations could bring about the difference Nash equilibria.展开更多
Wormhole attack is one of the most devastating threats for range-free localization in wireless sensor networks. In this paper, we evaluate three statistical estimation methods with the same network model and geographi...Wormhole attack is one of the most devastating threats for range-free localization in wireless sensor networks. In this paper, we evaluate three statistical estimation methods with the same network model and geographic information obtailaed by the DV-Hop algorithm. We analyze the limits of Minimum Mean Square Estimate （MMSE）, Least Median of Squares （LMS） and Enhanced greedy At- tack-Resistant MMSE （EARMMSE） and propose an improved EARMMSE with the hop-distance relationship, named EARMMSE＋. Simulation results illustrate the performance of MMSE, LMS and EARMMSE＋ with different anchor fraction, the length of wormhole link and the average local neighborhood and show that EARMMSE＋ outperforms MMSE and LMS.展开更多
基金supported by the National Basic Research Program of China(2011CB403504)the National Natural Science Foundation of China(41175025)
文摘In 2010-2012 spring, atmospheric duct observation experiments were performed throughout three open cruises over the South China Sea and the Tropical Eastern Indian Ocean. The data used for ducting analysis were measured by high resolution balloon-borne GPS radiosondes. Through data quality control and diagnostic analysis, the probability of ducting occurrence and characteristic quantities of the three typical ducts were given. The total percentage occurrence of evaporation duct, surface-based duct and elevated duct were 75.3%, 5% and 43.7%, respectively. The mean evaporation duct height was 15.3 m. The mean values of duct height, thickness and magnitude were 84.1 m, 14.9 m and 10 M-units for surfaced-based duct, and 1003.6 m, 62.2 m and 7.9 M-units for elevated duct. These preliminary statistical results can serve as a basis for future comprehensive and comparative studies of atmospheric duct for the research region.
文摘A game model is usually decided by three factors:players,strategies and pay-off functions.It’s easier to define the players and their strategies than their pay-off functions.Mostly,the pay-off functions need to be estimated,and the difference estimations could bring about the difference Nash equilibria.
基金Acknov,.4edgements This work was supported in part by National Basic Research Program of China （＂973 program＂） under contract No. 2007CB307101, and in part by National Natural Science Foundation of China under Grant No. 60833002, No. 60802016 and No.60972010.
文摘Wormhole attack is one of the most devastating threats for range-free localization in wireless sensor networks. In this paper, we evaluate three statistical estimation methods with the same network model and geographic information obtailaed by the DV-Hop algorithm. We analyze the limits of Minimum Mean Square Estimate （MMSE）, Least Median of Squares （LMS） and Enhanced greedy At- tack-Resistant MMSE （EARMMSE） and propose an improved EARMMSE with the hop-distance relationship, named EARMMSE＋. Simulation results illustrate the performance of MMSE, LMS and EARMMSE＋ with different anchor fraction, the length of wormhole link and the average local neighborhood and show that EARMMSE＋ outperforms MMSE and LMS.
