This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bil...This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bilinear, Natural and Nearest interpolation for missing data imputations. Performance indicators for these techniques were the root mean square error (RMSE), absolute mean error (AME), correlation coefficient and coefficient of determination ( R<sup>2</sup> ) adopted in this research. We randomly make 30% of total samples (total samples was 324) predictable from 70% remaining data. Although four interpolation methods seem good (producing <1 RMSE, AME) for imputations of air temperature data, but bilinear method was the most accurate with least errors for missing data imputations. RMSE for bilinear method remains <0.01 on all pressure levels except 1000 hPa where this value was 0.6. The low value of AME (<0.1) came at all pressure levels through bilinear imputations. Very strong correlation (>0.99) found between actual and predicted air temperature data through this method. The high value of the coefficient of determination (0.99) through bilinear interpolation method, tells us best fit to the surface. We have also found similar results for imputation with natural interpolation method in this research, but after investigating scatter plots over each month, imputations with this method seem to little obtuse in certain months than bilinear method.展开更多
The decay ψ(2S)→Ω-Ω+ is analyzed using 14×106 ψ(2S) events recorded by the Beijing Spectrometer Ⅱ (BESⅡ) at the Beijing Electron Positron Collider (BEPC). Based upon events with no missing charged...The decay ψ(2S)→Ω-Ω+ is analyzed using 14×106 ψ(2S) events recorded by the Beijing Spectrometer Ⅱ (BESⅡ) at the Beijing Electron Positron Collider (BEPC). Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ(2S)→Ω-Ω+ to be 1.5×104 at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω+ signal with a statistical signi cance of 3.1|σ. The branching fraction of ψ(2S)Ω+ is determined to be (4.80±1.56(stat)±1.30(sys))105.展开更多
文摘This research was an effort to select best imputation method for missing upper air temperature data over 24 standard pressure levels. We have implemented four imputation techniques like inverse distance weighting, Bilinear, Natural and Nearest interpolation for missing data imputations. Performance indicators for these techniques were the root mean square error (RMSE), absolute mean error (AME), correlation coefficient and coefficient of determination ( R<sup>2</sup> ) adopted in this research. We randomly make 30% of total samples (total samples was 324) predictable from 70% remaining data. Although four interpolation methods seem good (producing <1 RMSE, AME) for imputations of air temperature data, but bilinear method was the most accurate with least errors for missing data imputations. RMSE for bilinear method remains <0.01 on all pressure levels except 1000 hPa where this value was 0.6. The low value of AME (<0.1) came at all pressure levels through bilinear imputations. Very strong correlation (>0.99) found between actual and predicted air temperature data through this method. The high value of the coefficient of determination (0.99) through bilinear interpolation method, tells us best fit to the surface. We have also found similar results for imputation with natural interpolation method in this research, but after investigating scatter plots over each month, imputations with this method seem to little obtuse in certain months than bilinear method.
基金Supported by National Natural Science Foundation of China (10491300, 10225524, 10225525, 10425523, 10625524, 10521003, 10821063, 10825524), Chinese Academy of Sciences (KJ 95T-03), 100 Talents Program of CAS (U-11, U-24, U-25), Knowledge Innovation Project of CAS (U-602, U-34 (IHEP)), National Natural Science Foundation of China (10775077, 10225522) (Tsinghua University), and Department of Energy (DE-FG02-04ER41291) (U. Hawaii)
文摘The decay ψ(2S)→Ω-Ω+ is analyzed using 14×106 ψ(2S) events recorded by the Beijing Spectrometer Ⅱ (BESⅡ) at the Beijing Electron Positron Collider (BEPC). Based upon events with no missing charged tracks and a satisfactory four-constraint kinematic t, we determine the upper limit for the branching fraction of ψ(2S)→Ω-Ω+ to be 1.5×104 at a 90% confidence level. By including events with one missing charged track, we are able to report the first evidence of an Ω+ signal with a statistical signi cance of 3.1|σ. The branching fraction of ψ(2S)Ω+ is determined to be (4.80±1.56(stat)±1.30(sys))105.