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Investigation of Cross-Correlation Characteristics for Multi-Link Channels in High-Speed Railway Scenarios 被引量:1
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作者 Tao Zhou Cheng Tao +1 位作者 Liu Liu Kai Liu 《China Communications》 SCIE CSCD 2018年第8期108-117,共10页
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
关键词 high-speed railway communications multi-link channel CROSS-CORRELATION large-scale parameters small-scale fading.
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Dynamic analysis of multi-link spatial flexible manipulator arms with dynamic stiffening effects 被引量:1
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作者 Sijia Chen Dingguo Zhang Jun Liu 《Theoretical & Applied Mechanics Letters》 2012年第6期25-30,共6页
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
关键词 flexible manipulator arm multi-link flexible joint flexible link dynamic stiffening
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Finite-time complex projective synchronization of fractional-order complex-valued uncertain multi-link network and its image encryption application
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作者 Yong-Bing Hu Xiao-Min Yang +1 位作者 Da-Wei Ding Zong-Li Yang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第11期244-255,共12页
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
关键词 multi-links network fractional order complex-valued network finite-time complex projective synchronization image encryption
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A Humanoid Robot Gait Planning and Its Stability Validation
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作者 Jian Zeng Haibo Chen +1 位作者 Yan Yin Yan Yin 《Journal of Computer and Communications》 2014年第11期68-74,共7页
Gait planning based on linear inverted pendulum (LIPM) on structured road surface can be quickly generated because of the simple model and definite physical meaning. However, over-simplifi- cation of the model and dis... Gait planning based on linear inverted pendulum (LIPM) on structured road surface can be quickly generated because of the simple model and definite physical meaning. However, over-simplifi- cation of the model and discontents of zero velocity and acceleration boundary conditions when robot starts and stops walking lead to obvious difference between the model and the real robot. In this paper, parameterized gait is planned and trajectories’ smoothness of each joint angle and centroid are ensured using the 3-D LIPM theory. Static walking method is used to satisfy zero velocity and acceleration boundary conditions. Besides, a multi-link model is built to validate the stability. Simulation experiments show that: despite of some deviation from the theoretical solution, the actual zero-moment point (ZMP) is still within the support polygon, and the robot walks steadily. In consequence, the rationality and validity of model simplification of LIPM is demonstrated. 展开更多
关键词 HUMANOID Robot GAIT Planning 3-D LIPM STABILITY VALIDATION multi-link Model
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Preparation of Microcapsules Containing Water and Effect of Water Content on Expansion Behavior
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作者 Yoshinari Taguchi Natsukaze Saito +1 位作者 Kenji Oda Masato Tanaka 《Journal of Encapsulation and Adsorption Sciences》 2017年第4期127-139,共13页
The research work was conducted in order to establish the optimum conditions for preparing the expanded polystyrene beads without harmful substances and was aimed at the preparation of the microcapsules containing wat... The research work was conducted in order to establish the optimum conditions for preparing the expanded polystyrene beads without harmful substances and was aimed at the preparation of the microcapsules containing water and investigation of the effect of the water content on the expansion behavior of microcapsules. Microcapsules were prepared with the suspension polymerization method and the suspension polymerization in parallel with interfacial polycondensation method using the multiple emulsion (W/O)/W and adding a few additives. With increasing the crosslinking agent concentration in the suspension polymerization method, the water content increased from R = 5.8 wt% (CT = 0) to R = 8.2 wt% (CT = 4 wt%) and then, decreased to R = 7.5 wt% (CT = 9.0 wt%), while the expansion ratio increased from E = 1.01 (CT = 0) to E = 2.20 (CT = 4 wt%) and then, decreased to E = 1.01 (CT = 7.0 wt%). With increasing the added amount of wax in the suspension polymerization method, the water content gradually increased from R = 2.5 wt% to R = 8.0 wt%, while the expansion ratio increased from E = 1.01 to E = 1.5 and then, decreased. The water content and the expansion ratio could be increased by conducting suspension polymerization in parallel with interfacial polycondensation reaction from R = 5.0 wt % to R = 8.0 wt % and from E = 1.01 to E = 1.3, respectively. The maximum expansion ratio of E = 2.58 in this work was obtained under the conditions of crosslinking agent concentration of CT = 4.0 wt %, the added amount of wax of 3.0 g, addition of Agarose and the expansion temperature of T = 150°C. 展开更多
关键词 WATER CONTAINING MICROCAPSULES BLOWING Agent Expanded POLYSTYRENE sus-pension Polymerization Interfacial POLYCONDENSATION
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Operational-space wrench and acceleration capability analysis for multi-link cable-driven robots 被引量:1
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作者 SHENG XinJun TANG Lei +3 位作者 HUANG XinJia ZHU LiMin ZHU XiangYang GU GuoYing 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第10期2063-2072,共10页
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
关键词 multi-link cable-driven robots operational space capability analysis ZONOTOPE
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A Smooth and Efficient Gait Planning for Humanoids Based on Human ZMP 被引量:3
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作者 YANG Tianqi ZHANG Weimin +3 位作者 HUANG Qiang CHEN Xuechao YU Zhanguo MENG Libo 《机器人》 EI CSCD 北大核心 2017年第5期751-758,共8页
Based on the ZMP(zero moment point)trajectory and the walking data of human,a new method is proposed to improve the robot walking smoothness as well as to save energy.Firstly,a measurement system is designed to measur... Based on the ZMP(zero moment point)trajectory and the walking data of human,a new method is proposed to improve the robot walking smoothness as well as to save energy.Firstly,a measurement system is designed to measure the data of humans including the ZMP trajectory and the waist trajectory.Secondly,a new gait planning method which includes presetting the allowable ZMP region is proposed through analyzing human data.Thirdly,the new planning method is applied to the multi-link model based gait planning method.Finally,the feasibility of the proposed method is verified by simulation and experiments. 展开更多
关键词 gait planning multi-link model allowable ZMP(zero moment point) region ZMP planning algorithm
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