The high-precision terrestrial reference frame,as the spatial benchmark for geodesy,is an important national infrastructure.However,due to the influence of nonlinear factors related to geophysical phenomena,the overal...The high-precision terrestrial reference frame,as the spatial benchmark for geodesy,is an important national infrastructure.However,due to the influence of nonlinear factors related to geophysical phenomena,the overall maintenance accuracy of the ITRF framework is still at the centimeter level.Therefore,accurately characterizing the true trajectories of linear motion,nonlinear motion,and geocentric motion of the reference station is the key to achieve the construction and maintenance technology of a millimeter level terrestrial reference framework.Based on long-term global and regional GNSS observation data,more Chinese geodesy scientists devoted much efforts to the maintenance of millimeter-level geodetic reference framework.The main contributions of this work included the followings:①Dynamic maintenance of millimeter-level terrestrial reference frame;②Research progress on the method of maintenance of regional reference frame based on GNSS;③The progress of CGCS2000 frame maintenance in millimeter level accuracy;④Reprocessing and reanalysis of two-decade GNSS observation in continental China;⑤Research on current GNSS velocity field model and deformation in Chinese mainland;⑥The preliminary realization and evaluation of CTRF2020.展开更多
For the energy sharing problem of distributed antenna system(DAS)with energy harvesting(EH),a distributed antenna system model capable of sharing collected energy among the components in system is proposed.Compared wi...For the energy sharing problem of distributed antenna system(DAS)with energy harvesting(EH),a distributed antenna system model capable of sharing collected energy among the components in system is proposed.Compared with the existing model in literatures,the proposed model connects with smart grid through a unified interface and facilitates energy management and scheduling.Based on the proposed model,three kinds of energy sharing methods including the partial energy sharing method,the complete energy sharing method and the self-sustaining energy sharing method are analyzed.Under various energy sharing methods,the corresponding optimization problems of power allocation among the remote antenna units(RAUs)are described,formed and solved.As a result,the corresponding power allocation algorithm to each method has been concluded.Simulation results show that the proposed model is more efficient in terms of the channel capacity and energy efficiency,compared to the existing model.展开更多
Sporadic sodium layers(SSLs)were studied with sodium(Na)lidar at Beijing(40.5°N,116.0°E)and Haikou(19.5°N,109.1°E)in China.The altitude distribution,strength factors,and occurrence time of SSL and ...Sporadic sodium layers(SSLs)were studied with sodium(Na)lidar at Beijing(40.5°N,116.0°E)and Haikou(19.5°N,109.1°E)in China.The altitude distribution,strength factors,and occurrence time of SSL and sporadic E(Es)layer events were statistically analyzed at both observing sites.SSL occurrence had a maximum near22:00 local time,and Eslayer occurrence had a maximum before midnight.The altitude distributions of SSL and Es layer events were better correlated at Haikou than at Beijing.All the average values of height and strength factor for SSL and Eslayer events,as well as the average of the maximum frequency that can be reflected by the Eslayer(foEs),at Beijing were higher than those at Haikou.A better correlation between SSL and Eslayer events was also found at Haikou,and the formation of SSLs was considered to likely depend on the seasonal variability of chemical and dynamical processes.展开更多
基金National Natural Science Foundation of China(Nos.42274044,41974010,42330113,41804018)。
文摘The high-precision terrestrial reference frame,as the spatial benchmark for geodesy,is an important national infrastructure.However,due to the influence of nonlinear factors related to geophysical phenomena,the overall maintenance accuracy of the ITRF framework is still at the centimeter level.Therefore,accurately characterizing the true trajectories of linear motion,nonlinear motion,and geocentric motion of the reference station is the key to achieve the construction and maintenance technology of a millimeter level terrestrial reference framework.Based on long-term global and regional GNSS observation data,more Chinese geodesy scientists devoted much efforts to the maintenance of millimeter-level geodetic reference framework.The main contributions of this work included the followings:①Dynamic maintenance of millimeter-level terrestrial reference frame;②Research progress on the method of maintenance of regional reference frame based on GNSS;③The progress of CGCS2000 frame maintenance in millimeter level accuracy;④Reprocessing and reanalysis of two-decade GNSS observation in continental China;⑤Research on current GNSS velocity field model and deformation in Chinese mainland;⑥The preliminary realization and evaluation of CTRF2020.
基金This work is supported in part by the National Natural Science Foundation of China(Grant Number:61861006)the Guangxi Natural Science Foundation(Grant Number:2018GXNSFAA050062)Guangxi Postgraduate Education Innovation Project(Grant Number:XYCSZ2020054)。
文摘For the energy sharing problem of distributed antenna system(DAS)with energy harvesting(EH),a distributed antenna system model capable of sharing collected energy among the components in system is proposed.Compared with the existing model in literatures,the proposed model connects with smart grid through a unified interface and facilitates energy management and scheduling.Based on the proposed model,three kinds of energy sharing methods including the partial energy sharing method,the complete energy sharing method and the self-sustaining energy sharing method are analyzed.Under various energy sharing methods,the corresponding optimization problems of power allocation among the remote antenna units(RAUs)are described,formed and solved.As a result,the corresponding power allocation algorithm to each method has been concluded.Simulation results show that the proposed model is more efficient in terms of the channel capacity and energy efficiency,compared to the existing model.
基金supported by the National Natural Science Foundation of China (41264006,40905012 and 41174129)the Specialized Research Fund for State Key Laboratories of Chinathe data from the Chinese Meridian Project
文摘Sporadic sodium layers(SSLs)were studied with sodium(Na)lidar at Beijing(40.5°N,116.0°E)and Haikou(19.5°N,109.1°E)in China.The altitude distribution,strength factors,and occurrence time of SSL and sporadic E(Es)layer events were statistically analyzed at both observing sites.SSL occurrence had a maximum near22:00 local time,and Eslayer occurrence had a maximum before midnight.The altitude distributions of SSL and Es layer events were better correlated at Haikou than at Beijing.All the average values of height and strength factor for SSL and Eslayer events,as well as the average of the maximum frequency that can be reflected by the Eslayer(foEs),at Beijing were higher than those at Haikou.A better correlation between SSL and Eslayer events was also found at Haikou,and the formation of SSLs was considered to likely depend on the seasonal variability of chemical and dynamical processes.
