针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统对定时误差敏感,从叠加训练序列结构出发,提出了一种弱能量训练序列。该训练序列只叠加在循环前缀上,且比普通的重复结构训练序列能量要低,能降低由于叠加训练...针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统对定时误差敏感,从叠加训练序列结构出发,提出了一种弱能量训练序列。该训练序列只叠加在循环前缀上,且比普通的重复结构训练序列能量要低,能降低由于叠加训练序列对系统误码率的影响,还能利用训练序列的结构特点降低相关峰值旁瓣对同步判决的影响,提高了时间同步的准确率。在低信噪比时采用该训练序列结构,同步准确率高于采用普通重复结构训练序列的同步方法,最后通过计算机仿真验证了该方法的有效性。展开更多
In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice ...In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice of signal type for different exploration tasks.By the threshold of the amplitude of the transmitted signal,a set of candidate frequencies are first selected.Then,by operating a spectrum envelope method at these candidate frequencies on received data,effective components in data are extracted.A frequency density calculation method is proposed based on a logical number summation method,to reasonably characterize the frequency density in different frequency bands.By applying this method to real data in Sichuan,China,with signal Type 13,75 effective components are extracted,including both main frequencies and harmonics.The result suggests that the number of effective frequencies in the 2^(n) sequence pseudo-random signal can be increased by extracting usable harmonics,without any additional fieldwork.展开更多
The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in ...The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in groups by their energetic properties enables evaluation of the dependence of promoter strength on the energetic properties. The analysis of groups (clusters) of promoters distributed by the energy of DNA strands interaction in ?55, ?35, ?10 and +6 sequences indicates their connection with the transcriptional activity.展开更多
The basic parameters,seismogenic structure and seismic sequences characteristics of the Yutian MS7. 3 earthquake on February 12,2014 are introduced and compared to the Yutian MS7. 3 earthquake in 2008. The results sho...The basic parameters,seismogenic structure and seismic sequences characteristics of the Yutian MS7. 3 earthquake on February 12,2014 are introduced and compared to the Yutian MS7. 3 earthquake in 2008. The results show that the MS5. 4 earthquake is regarded as an immediate foreshock of the Yutian MS7. 3 main shock. The frequency of strong aftershock sequences was low and their number declined quickly,and the maximum aftershock was a MS5. 7 earthquake. According to analysis of the historical earthquake sequence type,and parameter of h-value,b-value and energy release ratio between main shock and sequence etc.,we found the preliminary conclusion that the Yutian MS7. 3 earthquake sequence in 2014 was a foreshock-main shock-aftershock type.展开更多
The Qianguo Ms5. 8 earthquake swarm of 2013 occurred in Qianguo, Jilin Province, China. There are five earthquakes with Ms ≥5. 0 in the Qianguo earthquake swarm, with magnitudes of Ms 5. 5, Ms 5. 0, Ms 5. 3, Ms 5. 8 ...The Qianguo Ms5. 8 earthquake swarm of 2013 occurred in Qianguo, Jilin Province, China. There are five earthquakes with Ms ≥5. 0 in the Qianguo earthquake swarm, with magnitudes of Ms 5. 5, Ms 5. 0, Ms 5. 3, Ms 5. 8 and Ms 5. 0. In this study, the far-field seismic radiated energy characteristics of the earthquakes are compared based on the source spectrum and the ground motion spectrum of the earthquake swarm. The ground motion spectrum of the five earthquakes at Changchun seismic station （CN2）, which is the national standard station, is first investigated with the recorded ground motions, and then the far-field seismic radiated energy is calculated and combined with the relationships of the source spectrum to describe the variable characteristics of the Qianguo earthquake swarm. Research results indicate that the second earthquake （No. 2） with Ms5. 0 is the key event of the earthquake swarm, which occurred on October 31, the same day following the first Ms5. 5 earthquake （No.l）. In fact, the magnitude of event No. 2 decreased compared to event No.l, which did not agree with its large far-field seismic radiated energy. It needs to be pointed out that event No. 2 was the turning point event of the Qianguo earthquake swarm, as being a significant transition before the largest Ms5. 8 earthquake.展开更多
文摘针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统对定时误差敏感,从叠加训练序列结构出发,提出了一种弱能量训练序列。该训练序列只叠加在循环前缀上,且比普通的重复结构训练序列能量要低,能降低由于叠加训练序列对系统误码率的影响,还能利用训练序列的结构特点降低相关峰值旁瓣对同步判决的影响,提高了时间同步的准确率。在低信噪比时采用该训练序列结构,同步准确率高于采用普通重复结构训练序列的同步方法,最后通过计算机仿真验证了该方法的有效性。
基金financially supported by the National Key Research and Development Program of China(No.2019YFC0604902)the National Natural Science Foundation of China(No.42004056)the Natural Science Foundation of Shandong Province,China(No.ZR201911010111).
文摘In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice of signal type for different exploration tasks.By the threshold of the amplitude of the transmitted signal,a set of candidate frequencies are first selected.Then,by operating a spectrum envelope method at these candidate frequencies on received data,effective components in data are extracted.A frequency density calculation method is proposed based on a logical number summation method,to reasonably characterize the frequency density in different frequency bands.By applying this method to real data in Sichuan,China,with signal Type 13,75 effective components are extracted,including both main frequencies and harmonics.The result suggests that the number of effective frequencies in the 2^(n) sequence pseudo-random signal can be increased by extracting usable harmonics,without any additional fieldwork.
文摘The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in groups by their energetic properties enables evaluation of the dependence of promoter strength on the energetic properties. The analysis of groups (clusters) of promoters distributed by the energy of DNA strands interaction in ?55, ?35, ?10 and +6 sequences indicates their connection with the transcriptional activity.
基金funded by the Open-end Foundation of State Key Laboratory of Earthquake Dynamics(LED2014B01)Project of Earthquake Science Foundation of Xinjiang,China(20120201)
文摘The basic parameters,seismogenic structure and seismic sequences characteristics of the Yutian MS7. 3 earthquake on February 12,2014 are introduced and compared to the Yutian MS7. 3 earthquake in 2008. The results show that the MS5. 4 earthquake is regarded as an immediate foreshock of the Yutian MS7. 3 main shock. The frequency of strong aftershock sequences was low and their number declined quickly,and the maximum aftershock was a MS5. 7 earthquake. According to analysis of the historical earthquake sequence type,and parameter of h-value,b-value and energy release ratio between main shock and sequence etc.,we found the preliminary conclusion that the Yutian MS7. 3 earthquake sequence in 2014 was a foreshock-main shock-aftershock type.
基金funded by the National Natural Science Foundation,China(Grant No.41404045,No.41504047)
文摘The Qianguo Ms5. 8 earthquake swarm of 2013 occurred in Qianguo, Jilin Province, China. There are five earthquakes with Ms ≥5. 0 in the Qianguo earthquake swarm, with magnitudes of Ms 5. 5, Ms 5. 0, Ms 5. 3, Ms 5. 8 and Ms 5. 0. In this study, the far-field seismic radiated energy characteristics of the earthquakes are compared based on the source spectrum and the ground motion spectrum of the earthquake swarm. The ground motion spectrum of the five earthquakes at Changchun seismic station （CN2）, which is the national standard station, is first investigated with the recorded ground motions, and then the far-field seismic radiated energy is calculated and combined with the relationships of the source spectrum to describe the variable characteristics of the Qianguo earthquake swarm. Research results indicate that the second earthquake （No. 2） with Ms5. 0 is the key event of the earthquake swarm, which occurred on October 31, the same day following the first Ms5. 5 earthquake （No.l）. In fact, the magnitude of event No. 2 decreased compared to event No.l, which did not agree with its large far-field seismic radiated energy. It needs to be pointed out that event No. 2 was the turning point event of the Qianguo earthquake swarm, as being a significant transition before the largest Ms5. 8 earthquake.
