A generalized ionospheric dispersion simulation method is presented to verify and test wideband satellite-ground-link radio systems for dispersion robustness. In the method, ionospheric dispersive effects on wideband ...A generalized ionospheric dispersion simulation method is presented to verify and test wideband satellite-ground-link radio systems for dispersion robustness. In the method, ionospheric dispersive effects on wideband radio waves are modeled as an allpass nonlinear phase system, thus greatly decreasing the need for signal priori information. To accurately simulate the ionospheric dis- persion and reduce the implementation complexity, the system is decomposed into three new allpass subsystems： with a linear phase passing through zero frequency, a constant phase, and a nonlinear phase with zero-offset and quasi-parabolic form respectively. The three subsystems are implemented respectively by the combination of integer-interval delay and fractional delay filter, digital shifting phase and the complex-coefficient finite impulse response （ FIR ） filter. The ionospheric dispersion simulation can be achieved by cascading the three subsystems in a complex baseband and converting the frequency to a radio frequency. Simulation results show that the method has the ability to accu- rately simulate the ionospheric dispersion characteristics without knowing the signal priori informa- tion and has a low implementation complexity.展开更多
We present in this paper a structural decomposition for linear multivariable singular systems. Such a decomposition has a distinct feature of capturing and displaying all the structural properties, such as the finite ...We present in this paper a structural decomposition for linear multivariable singular systems. Such a decomposition has a distinct feature of capturing and displaying all the structural properties, such as the finite and infinite zero structures, invertibility structures, and redundant dynamics of the given system. As its counterpart for non-singular systems, we believe that the technique is a powerful tool in solving control problems for singular systems.展开更多
In this paper, consensus problems in discrete-time multiagent systems with time-invariant delays are considered. In order to characterize the structures of communication topologies, the concept of ＂pre-leader-followe...In this paper, consensus problems in discrete-time multiagent systems with time-invariant delays are considered. In order to characterize the structures of communication topologies, the concept of ＂pre-leader-follower＂ decomposition is introduced. Then, a necessary and sufficient condition for state consensus is established. By this method, consensus problems in networks with a single time-delay, as well as with multiple time-delays, are studied, and some necessary and sufficient conditions for solvability of consensus problems are obtained.展开更多
Due to the limited bandwidth and transmission congestion of the vehicle platoon's communication,it is inevitable to induce time delay,which significantly degrades the control performance of the vehicle platoon,eve...Due to the limited bandwidth and transmission congestion of the vehicle platoon's communication,it is inevitable to induce time delay,which significantly degrades the control performance of the vehicle platoon,even resulting in instability.This paper focuses on analyzing the internal stability under generic communication topologies and presents a method of computing the exact time delay margin(ETDM).The proposed method can offer a necessary and sufficient internal stability condition with no conservatism.Firstly,to reduce the analytical complexity and computational burden elegantly,we decompose the closed-loop platoon dynamics into a set of individual subsystems via similarity transformation and matrix factorization.This decomposition approach is applicable for any general communication topology.Secondly,an explicit formula is deduced to compute the ETDM by surveying the characteristic roots'distribution of all these individual subsystems.It is further demonstrated that only the positive purely imaginary roots need to be considered to compute the ETDM.Finally,simulations are conducted to demonstrate the effectiveness of the theoretical claims.展开更多
基金Supported by the Foundation of Shanghai Aerospace Science and Technology(20120541088)China Postdoctoral Science Foundation(2015M580997)
文摘A generalized ionospheric dispersion simulation method is presented to verify and test wideband satellite-ground-link radio systems for dispersion robustness. In the method, ionospheric dispersive effects on wideband radio waves are modeled as an allpass nonlinear phase system, thus greatly decreasing the need for signal priori information. To accurately simulate the ionospheric dis- persion and reduce the implementation complexity, the system is decomposed into three new allpass subsystems： with a linear phase passing through zero frequency, a constant phase, and a nonlinear phase with zero-offset and quasi-parabolic form respectively. The three subsystems are implemented respectively by the combination of integer-interval delay and fractional delay filter, digital shifting phase and the complex-coefficient finite impulse response （ FIR ） filter. The ionospheric dispersion simulation can be achieved by cascading the three subsystems in a complex baseband and converting the frequency to a radio frequency. Simulation results show that the method has the ability to accu- rately simulate the ionospheric dispersion characteristics without knowing the signal priori informa- tion and has a low implementation complexity.
文摘We present in this paper a structural decomposition for linear multivariable singular systems. Such a decomposition has a distinct feature of capturing and displaying all the structural properties, such as the finite and infinite zero structures, invertibility structures, and redundant dynamics of the given system. As its counterpart for non-singular systems, we believe that the technique is a powerful tool in solving control problems for singular systems.
基金the National Natural Science Foundation of China (Grant Nos. 60674050 and 60528007)the National 973 Program (Grant No.2002CB312200)+1 种基金the National 863 Program (Grant No. 2006AA04Z258)11-5 project (Grant No. A2120061303)
文摘In this paper, consensus problems in discrete-time multiagent systems with time-invariant delays are considered. In order to characterize the structures of communication topologies, the concept of ＂pre-leader-follower＂ decomposition is introduced. Then, a necessary and sufficient condition for state consensus is established. By this method, consensus problems in networks with a single time-delay, as well as with multiple time-delays, are studied, and some necessary and sufficient conditions for solvability of consensus problems are obtained.
基金supported in by National Natural Science Foundation of China(No.62003054,52372406)Key Research and Development Program of Shaanxi Province(Nos.2023-YBGY398)Fundamental Research Funds for the Central Universities(No.300102320109)。
文摘Due to the limited bandwidth and transmission congestion of the vehicle platoon's communication,it is inevitable to induce time delay,which significantly degrades the control performance of the vehicle platoon,even resulting in instability.This paper focuses on analyzing the internal stability under generic communication topologies and presents a method of computing the exact time delay margin(ETDM).The proposed method can offer a necessary and sufficient internal stability condition with no conservatism.Firstly,to reduce the analytical complexity and computational burden elegantly,we decompose the closed-loop platoon dynamics into a set of individual subsystems via similarity transformation and matrix factorization.This decomposition approach is applicable for any general communication topology.Secondly,an explicit formula is deduced to compute the ETDM by surveying the characteristic roots'distribution of all these individual subsystems.It is further demonstrated that only the positive purely imaginary roots need to be considered to compute the ETDM.Finally,simulations are conducted to demonstrate the effectiveness of the theoretical claims.
