The Global Navigation Satellite System(GNSS)has been widely adopted in numerous fields,including intelligent transportation,remote sensing,and aeronautical and astronautical engineering.As new navigation approaches,te...The Global Navigation Satellite System(GNSS)has been widely adopted in numerous fields,including intelligent transportation,remote sensing,and aeronautical and astronautical engineering.As new navigation approaches,technologies,and applications continue to emerge,they attract significant global attention.Ensuring reliable positioning solutions with high accuracy,strong anti-interference capabilities,high availability and low integrity risks has become increasingly critical.展开更多
＂Backwash＂ has usually been described in terms of the effect of testing on language teaching and learning. ＂Backwash can be harmful or beneficial＂, as Arthur Hughes states. （Hughes： 1989） This paper set out to ...＂Backwash＂ has usually been described in terms of the effect of testing on language teaching and learning. ＂Backwash can be harmful or beneficial＂, as Arthur Hughes states. （Hughes： 1989） This paper set out to see how far this term can be applied to the ways in which both the students and teachers can benefit from language testing.展开更多
Time delay-based the 5th Generation Mobile Communication Technology(5G)positioning is a main method to perform high-precision positioning in Global Navigation Satellite System(GNSS)denied areas.However,in practical ap...Time delay-based the 5th Generation Mobile Communication Technology(5G)positioning is a main method to perform high-precision positioning in Global Navigation Satellite System(GNSS)denied areas.However,in practical applications,the occlusion of signals in a complex environment results in few observable base stations,which affects the reliability and accuracy of positioning.The aim of this study is to improve the performance of the 5G positioning in complex environments with an insufficient number of observable base stations.First,the Angle of Departure(AOD)capability of multi-antennas is integrated into Multi-Round-Trip-Time(Multi-RTT)positioning,establishing a novel 5G RTT/AOD positioning model.Then,the influencing factors of positioning performance,including the Dilution of Precision(DOP)and the accuracy of the AOD measurements,is analyzed.The relationship between DOP and RTT/AOD positioning accuracy is deduced.Afterwards,simulation experiments are performed on 5G positioning with the Multi-RTT and RTT/AOD methods in two scenarios with good and complex environments.The theoretical analysis and experimental results show that 5G positioning with the RTT/AOD method increases the horizontal and vertical accuracies by approximately 25 and 65%,respectively,compared with the Multi-RTT method.The positioning reliability is also greatly improved.The proposed model can well solve the inefficiency of 5G positioning with the RTT method in scenarios where the number of base stations is less than three.展开更多
文摘The Global Navigation Satellite System(GNSS)has been widely adopted in numerous fields,including intelligent transportation,remote sensing,and aeronautical and astronautical engineering.As new navigation approaches,technologies,and applications continue to emerge,they attract significant global attention.Ensuring reliable positioning solutions with high accuracy,strong anti-interference capabilities,high availability and low integrity risks has become increasingly critical.
文摘＂Backwash＂ has usually been described in terms of the effect of testing on language teaching and learning. ＂Backwash can be harmful or beneficial＂, as Arthur Hughes states. （Hughes： 1989） This paper set out to see how far this term can be applied to the ways in which both the students and teachers can benefit from language testing.
基金Grant No.2018YFC0809804National Science Foundation of China under Grant No.41974038major consulting research project of the Chinese Academy of Engineering(HB2020B13).
文摘Time delay-based the 5th Generation Mobile Communication Technology(5G)positioning is a main method to perform high-precision positioning in Global Navigation Satellite System(GNSS)denied areas.However,in practical applications,the occlusion of signals in a complex environment results in few observable base stations,which affects the reliability and accuracy of positioning.The aim of this study is to improve the performance of the 5G positioning in complex environments with an insufficient number of observable base stations.First,the Angle of Departure(AOD)capability of multi-antennas is integrated into Multi-Round-Trip-Time(Multi-RTT)positioning,establishing a novel 5G RTT/AOD positioning model.Then,the influencing factors of positioning performance,including the Dilution of Precision(DOP)and the accuracy of the AOD measurements,is analyzed.The relationship between DOP and RTT/AOD positioning accuracy is deduced.Afterwards,simulation experiments are performed on 5G positioning with the Multi-RTT and RTT/AOD methods in two scenarios with good and complex environments.The theoretical analysis and experimental results show that 5G positioning with the RTT/AOD method increases the horizontal and vertical accuracies by approximately 25 and 65%,respectively,compared with the Multi-RTT method.The positioning reliability is also greatly improved.The proposed model can well solve the inefficiency of 5G positioning with the RTT method in scenarios where the number of base stations is less than three.
