The important effects of snow cover to ground thermal decades. In the most of previous research, the effects were usually regime has received much attention of scholars during the past few evaluated through the numeri...The important effects of snow cover to ground thermal decades. In the most of previous research, the effects were usually regime has received much attention of scholars during the past few evaluated through the numerical models and many important results are found. However, less examples and insufficient data based on field measurements are available to show natural cases. In the present work, a typical case study in Mohe and Beijicun meteorological stations, which both are located in the most northern tip of China, is given to show the effects of snow cover on the ground thermal regime. The spatial （the ground profile） and time series analysis in the extremely snowy winter of 2012-2013 in Heilongjiang Province are also performed by contrast with those in the winter of 2011-2012 based on the measured data collected by 63 meteorological stations, Our results illustrate the positive （warmer） effect of snow cover on the ground temperature （GT） on the daily basis, the highest difference between GT and daily mean air temperature （DGAT） is as high as 32.35℃. Moreover, by the lag time analysis method it is found that the response time of GT from 0 cm to 20 cm ground depth to the alternate change of snow depth has 10 days lag, while at 40 cm depth the response of DGAT is not significant. This result is different from the previous research by modeling, in which the resnonse denth of ground to the alteration of snow depth is far more than 40 cm.展开更多
In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlatio...In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41471289,41301368)Natural Science Foundation of Jilin Province(No.20140101158JC)Foundation of State Key Laboratory of Remote Sensing Science(No.OFSLRSS201517)
文摘The important effects of snow cover to ground thermal decades. In the most of previous research, the effects were usually regime has received much attention of scholars during the past few evaluated through the numerical models and many important results are found. However, less examples and insufficient data based on field measurements are available to show natural cases. In the present work, a typical case study in Mohe and Beijicun meteorological stations, which both are located in the most northern tip of China, is given to show the effects of snow cover on the ground thermal regime. The spatial （the ground profile） and time series analysis in the extremely snowy winter of 2012-2013 in Heilongjiang Province are also performed by contrast with those in the winter of 2011-2012 based on the measured data collected by 63 meteorological stations, Our results illustrate the positive （warmer） effect of snow cover on the ground temperature （GT） on the daily basis, the highest difference between GT and daily mean air temperature （DGAT） is as high as 32.35℃. Moreover, by the lag time analysis method it is found that the response time of GT from 0 cm to 20 cm ground depth to the alternate change of snow depth has 10 days lag, while at 40 cm depth the response of DGAT is not significant. This result is different from the previous research by modeling, in which the resnonse denth of ground to the alteration of snow depth is far more than 40 cm.
基金supported by the Scientific Research Foundation for the Doctor′s Degree,Beijing University of Technology(No.X0002012200903)the State Key Laboratory of Integrated Services Networks(Xidian University),China(No.ISN10-02)
文摘In this paper, a group of methttis in reducing Peak to Average Power Ratio （PAPR） in 3GPP-LTE uplink Single-Carrier Fre-quency Division Multiple Access （SC-FDMA） using Constant Amplitude. tude Zero Auto-Correlation Sequences（CAZAC） sequences were proposed. The authors discussed the methods of reducing PAPR using pilot sequences and detailed schemes. Then they investigated several CAZAC sequences, mainly about phase shifted sequences, such as Chu sequence, Frank sequence and Golomb sequence. They also the differences between various kinds of pilot sequence positions. Compared to simple binary sequences, CAZAC has a great improvement in peak power reduction. With respect to pilot sequence orders and pilot density, all three CAZAC sequences have similar performances, which is an advantage in designing SC-FDMA systems.
