This paper investigates the cross-correlation characteristics of large-scale parameters(LSPs) and small-scale fading(SSF) for high-speed railway(HSR) multilink propagation scenarios, based on realistic measurements co...This paper investigates the cross-correlation characteristics of large-scale parameters(LSPs) and small-scale fading(SSF) for high-speed railway(HSR) multilink propagation scenarios, based on realistic measurements conducted on Beijing to Tianjin HSR line in China. A long-term evolution-based channel sounding system is utilized in the measurements to obtain the channel data. By applying a proposed time-delay based dynamic partition method, multi-link channel impulse responses are extracted from the raw channel data. Then, the statistical results of LSPs, including shadow fading, K-factor, and root-mean-square delay spread are derived and the cross-correlation coefficients of these LPSs are calculated. Moreover, the SSF spatial correlation and cross-correlation of SSF are analyzed. These results can be used to exploit multi-link channel model and to optimize the next-generation HSR communication system.展开更多
The dynamics for multi-link spatial flexible manipulator arms is investigated. The system considered here is an N-flexible-link manipulator driven by N DC-motors through N revolute flexiblejoints. The flexibility of e...The dynamics for multi-link spatial flexible manipulator arms is investigated. The system considered here is an N-flexible-link manipulator driven by N DC-motors through N revolute flexiblejoints. The flexibility of each flexible joint is modeled as a linearly elastic torsional spring, and the mass of the joint is also considered. For the flexibility of the link, all of the stretching deformation, bending deformation and the torsional deformation are included. The complete governing equations of motion of the system are derived via the Lagrange equations. The nonlinear description of the deformation field of the flexible link is adopted in the dynamic modeling, and thus the dynamic stiffening effects are captured. Based on this model, a general-purpose software package for dynamic simulation of multi-link spatial flexible manipulator arms is developed. Several illustrative examples are given to validate the algorithm presented in this paper and to indicate that not only dynamic stiffening effects but also the flexibility of the structure has significant influence on the dynamic performance of the manipulator.展开更多
Multi-link networks are universal in the real world such as relationship networks,transportation networks,and communication networks.It is significant to investigate the synchronization of the network with multi-link....Multi-link networks are universal in the real world such as relationship networks,transportation networks,and communication networks.It is significant to investigate the synchronization of the network with multi-link.In this paper,considering the complex network with uncertain parameters,new adaptive controller and update laws are proposed to ensure that complex-valued multilink network realizes finite-time complex projective synchronization(FTCPS).In addition,based on fractional-order Lyapunov functional method and finite-time stability theory,the criteria of FTCPS are derived and synchronization time is given which is associated with fractional order and control parameters.Meanwhile,numerical example is given to verify the validity of proposed finite-time complex projection strategy and analyze the relationship between synchronization time and fractional order and control parameters.Finally,the network is applied to image encryption,and the security analysis is carried out to verify the correctness of this method.展开更多
Multi-link cable-driven robots(MCDRs)have potential advantages in confined spaces exploration because of their redundancy and flexibility.Operational space wrench and acceleration capability analysis of MCDRs is impor...Multi-link cable-driven robots(MCDRs)have potential advantages in confined spaces exploration because of their redundancy and flexibility.Operational space wrench and acceleration capability analysis of MCDRs is important for their design,manipulability optimization,and motion planning.However,existing works mainly focus on capability analysis in the joint space.In this paper,we present a zonotope-based iterative method and a simplified capability zonotope to analyze the operational-space wrench and acceleration capability of MCDRs.In the iterative method,the capability generated by some cables can be iteratively added to the initial capability zonotope based on the Minkowski sum.In the simplified zonotope capability representation,a threshold is put forward to reduce redundant vertices and faces with little volume loss.Finally,simulations on a 24 DOFs MCDR are performed to verify the effectiveness of the developed method.The results demonstrate that our iterative algorithm can easily generate the capability zonotope with a few MB ROM,while traditional operational wrench capability evaluation without our iterative algorithm needs 18432 GB ROM.Furthermore,our simplified representation reduces the vertices and faces from 1260 and 2516 to 88 and 172,respectively,but with only 3.3%volume loss,which decreases the constraints of the robot and is conducive to manipulability optimization and motion planning.展开更多
基金supported by the Beijing Municipal Natural Science Foundation under Grant 4174102the National Natural Science Foundation of China under Grant 61701017+1 种基金the Open Research Fund through the National Mobile Communications Research Laboratory, Southeast University, under Grant 2018D11the Fundamental Research Funds for the Central Universities under Grant 2018JBM003
文摘This paper investigates the cross-correlation characteristics of large-scale parameters(LSPs) and small-scale fading(SSF) for high-speed railway(HSR) multilink propagation scenarios, based on realistic measurements conducted on Beijing to Tianjin HSR line in China. A long-term evolution-based channel sounding system is utilized in the measurements to obtain the channel data. By applying a proposed time-delay based dynamic partition method, multi-link channel impulse responses are extracted from the raw channel data. Then, the statistical results of LSPs, including shadow fading, K-factor, and root-mean-square delay spread are derived and the cross-correlation coefficients of these LPSs are calculated. Moreover, the SSF spatial correlation and cross-correlation of SSF are analyzed. These results can be used to exploit multi-link channel model and to optimize the next-generation HSR communication system.
基金supported by the National Natural Science Foundations of China (10772085,11272155 and 11132007)333 Project of Jiangsu Province,China(BRA2011172)NUST Research Funding,China(2011YBXM32)
文摘The dynamics for multi-link spatial flexible manipulator arms is investigated. The system considered here is an N-flexible-link manipulator driven by N DC-motors through N revolute flexiblejoints. The flexibility of each flexible joint is modeled as a linearly elastic torsional spring, and the mass of the joint is also considered. For the flexibility of the link, all of the stretching deformation, bending deformation and the torsional deformation are included. The complete governing equations of motion of the system are derived via the Lagrange equations. The nonlinear description of the deformation field of the flexible link is adopted in the dynamic modeling, and thus the dynamic stiffening effects are captured. Based on this model, a general-purpose software package for dynamic simulation of multi-link spatial flexible manipulator arms is developed. Several illustrative examples are given to validate the algorithm presented in this paper and to indicate that not only dynamic stiffening effects but also the flexibility of the structure has significant influence on the dynamic performance of the manipulator.
文摘Multi-link networks are universal in the real world such as relationship networks,transportation networks,and communication networks.It is significant to investigate the synchronization of the network with multi-link.In this paper,considering the complex network with uncertain parameters,new adaptive controller and update laws are proposed to ensure that complex-valued multilink network realizes finite-time complex projective synchronization(FTCPS).In addition,based on fractional-order Lyapunov functional method and finite-time stability theory,the criteria of FTCPS are derived and synchronization time is given which is associated with fractional order and control parameters.Meanwhile,numerical example is given to verify the validity of proposed finite-time complex projection strategy and analyze the relationship between synchronization time and fractional order and control parameters.Finally,the network is applied to image encryption,and the security analysis is carried out to verify the correctness of this method.
基金the China National Key R&D Program(Grant No.2019YFB1311204)the Shanghai Jiao Tong University Scientific and Technological Innovation Funds。
文摘Multi-link cable-driven robots(MCDRs)have potential advantages in confined spaces exploration because of their redundancy and flexibility.Operational space wrench and acceleration capability analysis of MCDRs is important for their design,manipulability optimization,and motion planning.However,existing works mainly focus on capability analysis in the joint space.In this paper,we present a zonotope-based iterative method and a simplified capability zonotope to analyze the operational-space wrench and acceleration capability of MCDRs.In the iterative method,the capability generated by some cables can be iteratively added to the initial capability zonotope based on the Minkowski sum.In the simplified zonotope capability representation,a threshold is put forward to reduce redundant vertices and faces with little volume loss.Finally,simulations on a 24 DOFs MCDR are performed to verify the effectiveness of the developed method.The results demonstrate that our iterative algorithm can easily generate the capability zonotope with a few MB ROM,while traditional operational wrench capability evaluation without our iterative algorithm needs 18432 GB ROM.Furthermore,our simplified representation reduces the vertices and faces from 1260 and 2516 to 88 and 172,respectively,but with only 3.3%volume loss,which decreases the constraints of the robot and is conducive to manipulability optimization and motion planning.
