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Mitigation of EDFA transient effects in Variable duty cycle pulsed signals

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Defence Technology（防务技术） 2019年第3期15卷 276-281页

作者： D. Meena K.T. Sarath Fredy Francis E. Dipin T. Srinivas Electronics and Radar Development Establishment (LRDE) DRDO Bangalore Karnataka 560093 India Model Engineering College Thrikkakara Cochin Kerala 682021 India Indian Institute of Technology Madras Chennai Tamil Nadu 600036 India

We report the transient effects in Erbium Doped Fiber Amplifier (EDFA) systems for pulsed signals with different duty-cycles. The work includes the analysis using three different duty-cycles, 10%, 20% and 50%. A curve fitting technique is also proposed to predict the transients of any lesser duty-cycled pulse, once the transients of a larger duty-cycled pulse is known. Mathematical evaluation confirms the double exponential shape of transient distorted signal. Further, EDFA transient effect is experimentally verified on a Wavelength Division Multiplexed (WDM) link by multiplexing high and low bitrate modulated optical signals. We conclude the paper by proposing a transient suppression technique for Variable dutycycle signals and analyzing its effectiveness with different wavelength spacing.

关键词： EDFA Transients WDM Variable duty cycle Suppression

Latent Variable Regression for Supervised Modeling and Monitoring

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IEEE/CAA Journal of Automatica Sinica 2020年第3期7卷 800-811页

作者： Qinqin Zhu Department of Chemical Engineering University of WaterlooON N2L 3G1Canada

A latent Variable regression algorithm with a regularization term(r LVR) is proposed in this paper to extract latent relations between process data X and quality data Y. In rLVR,the prediction error between X and Y is minimized, which is proved to be equivalent to maximizing the projection of quality Variables in the latent space. The geometric properties and model relations of rLVR are analyzed, and the geometric and theoretical relations among r LVR, partial least squares, and canonical correlation analysis are also presented. The rLVR-based monitoring framework is developed to monitor process-relevant and quality-relevant variations simultaneously. The prediction and monitoring effectiveness of rLVR algorithm is demonstrated through both numerical simulations and the Tennessee Eastman(TE) process.

关键词： Data analytics inferential monitoring latent Variable regression regularization

A novel Variable topology design for a multi-flexible ejection mechanism

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Defence Technology（防务技术） 2020年第2期16卷 432-438页

作者： Hao Liu Jun Zhou Zong-lai Mo Shi-wei Zhang School of Astronautics Northwestern Polytechnical UniversityXi'an710072China School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China Luoyang Opto-Electro Technology Development Center 471009China

The airborne missile launch mechanism often subjects to significant deformations induced by the large ejection force during high-speed actuations in missile ejection process,leading to a substantial deviation of separation parameters from designed values that threats safety of the carrier.This study proposes a novel Variable topology design for launch mechanism,achieved via a Prsmatic-Revolute-Revolute pair(PR-R)motion formed by the structural gap with a specific direction.It enables launch mechanism variability during missile ejection process and optimizes the ejection force given by the front and back ejection arms,and greatly optimizes the separation parameters during missile ejection.The kinetics simulation analysis is conducted under working conditions of the original ejection mechanism and the novel mechanism with Variable topology design,respectively.The results show that the novel Variable topology design is more befitting for the launch process in terms of system safety and controllability,effectively improving the separation posture,restraining the flexible effect of the mechanism,and fulfilling the effectiveness of the design value of multi-rigid body.

关键词： Variable topology Gap dynamics Multi-flexible body Flexible control Ejection mechanism

Analysis of the mass of behind-armor debris generated by RHA subjected to normal penetration of Variable cross-section EFP

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Defence Technology（防务技术） 2019年第3期15卷 390-397页

作者： Boyang Xing Dongjiang Zhang Zhenyan Guo Yunhui Hou Rui Guo Rongzhong Liu Liang Chen Hao Zhou Yongliang Yang Jianhua Luo School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 Jiangsu China Xi'an Modern Control Technology Research Institute Xi'an 710065 Shanxi China School of Electronic and Optical Engineering Nanjing University of Science and Technology Nanjing 210094 China

Analyzing the mass of behind-armor debris (BAD) generated by Rolled Homogeneous Armor (RHA) subjected to normal penetration of Variable cross-section Explosively Formed Projectile (EFP) is the purpose of this paper. So theoretical analysis, numerical simulation and experimental data are combined to analyze the influence of Variable cross-section characteristic on the time history of crater radius. Moreover the relationships between time history of crater radius (as well as mass of BAD) and the thickness of RHA (from 30mm to 70 mm) and the impact velocity of EFP (1650 m/s to 1860 m/s) are also investigated. The results indicate that: 1) being compared to the Variable cross-section characteristic is ignored, the theoretical time history of crater radius is in better agreement with the simulation results when the Variable cross-section characteristic is considered;2) being compared to the other three conditions of plug, the theoretical mass of BAD is in the best agreement with the simulation results when the shape of plug is frustum of a cone and the angle between generatrix and bottom is 45- and the axial length of mushroom is considered.

关键词： Explosively formed projectile Behind-armor debris Variable cross-section characteristic Shape of plug Axial length of mushroom Theoretical model

Pythagorean Uncertain Linguistic Variable Hamy Mean Operator and Its Application to Multi-attribute Group Decision Making

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IEEE/CAA Journal of Automatica Sinica 2019年第2期6卷 527-539页

作者： Huidong Wang Shifan He Chengdong Li Xiaohong Pan IEEE the School of Management Science and Engineering Shandong University of Finance and Economics the School of Information and Electrical Engineering Shandong Jianzhu University

Pythagorean fuzzy set(PFS) can provide more flexibility than intuitionistic fuzzy set(IFS) for handling uncertain information, and PFS has been increasingly used in multi-attribute decision making problems. This paper proposes a new multiattribute group decision making method based on Pythagorean uncertain linguistic Variable Hamy mean(PULVHM) operator and VIKOR method. Firstly, we define operation rules and a new aggregation operator of Pythagorean uncertain linguistic Variable(PULV) and explore some properties of the operator.Secondly, taking the decision makers' hesitation degree into account, a new score function is defined, and we further develop a new group decision making approach integrated with VIKOR method. Finally, an investment example is demonstrated to elaborate the validity of the proposed method. Sensibility analysis and comprehensive comparisons with another two methods are performed to show the stability and advantage of our method.

关键词： Hamy mean(HM) operator multi-attribute group decision making(MAGDM) Pythagorean fuzzy set Pythagorean uncertain linguistic Variable

Switching disturbance rejection attitude control of near space vehicles with Variable structure

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Journal of Systems Engineering and Electronics 2019年第1期30卷 167-179页

作者： GONG Ligang WANG Qing DONG Chaoyang School of Automation Science and Electrical Engineering Beihang University School of Aeronautic Science and Engineering Beihang University

A switching disturbance rejection attitude control law is proposed for a near space vehicle(NSV) with Variable structure.The multiple flight modes, system uncertainties and disturbances of the NSV are taken into account based on switched nonlinear systems. Compared with traditional backstepping design methods,the proposed method utilizes the added integrals of attitude angle and angular rate tracking errors to further decrease the tracking errors. Moreover, to reduce the computation complexity, a rapid convergent differentiator is employed to obtain the derivative of the virtual control command. Finally, for disturbance rejection, based on the idea from the extended state observer(ESO), two disturbance observers are designed by using non-smooth functions to estimate the disturbances in the switched nonlinear systems. All signals of the closed-loop system are proven to be uniformly ultimately bounded under the Lyapunov function framework. Simulation results demonstrate the effectiveness of the proposed control scheme.

关键词： near space vehicle (NSV) Variable structure switched nonlinear system extended state observer (ESO).

Environmental Adaptive Control of a Snake-like Robot With Variable Stiffness Actuators

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IEEE/CAA Journal of Automatica Sinica 2020年第3期7卷 745-751页

作者： Dong Zhang Hao Yuan Zhengcai Cao IEEE College of Information Science and Technology Beijing University of Chemical TechnologyBeijing 100029China

This work investigates adaptive stiffness control and motion optimization of a snake-like robot with Variable stiffness actuators. The robot can vary its stiffness by controlling magnetorheological fluid(MRF) around actuators. In order to improve the robot's physical stability in complex environments, this work proposes an adaptive stiffness control strategy. This strategy is also useful for the robot to avoid disturbing caused by emergency situations such as collisions. In addition, to obtain optimal stiffness and reduce energy consumption, both torques of actuators and stiffness of the MRF braker are considered and optimized by using an evolutionary optimization algorithm. Simulations and experiments are conducted to verify the proposed adaptive stiffness control and optimization methods for a Variable stiffness snake-like robots.

关键词： Adaptive control snake-like robot Variable stiffness

Littlewood–Paley Operators on Spaces with Variable Exponent on Homogeneous Groups

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Acta Mathematica Sinica,English Series 2020年第5期36卷 535-558页

作者： Dong Li LIU Ji Man ZHAO Key Laboratory of Mathematics and Complex Systems Ministry of Education Institution of Mathematics and Mathematical Education School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

In this paper,on homogeneous groups,we study the Littlewood–Paley operators in Variable exponent spaces.First,we prove that the weighted Littlewood–Paley operators are controlled by the weighted Hardy–Littlewood maximal function,and obtain the vector-valued inequalities of the Littlewood–Paley operators,including the Lusin function,Littlewood–Paley g function and gλ* function.Second,we prove the boundedness of multilinear Littlewood–Paley gψ,λ* function.

关键词： Littlewood–Paley operators Variable Lebesgue spaces homogeneous groups

New normalized LMS adaptive filter with a Variable regularization factor

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Journal of Systems Engineering and Electronics 2019年第2期30卷 259-269页

作者： LI Zhoufan LI Dan XU Xinlong ZHANG Jianqiu School of Information Science and Technology Fudan University

A new normalized least mean square(NLMS) adaptive filter is first derived from a cost function, which incorporates the conventional one of the NLMS with a minimum-disturbance(MD)constraint. A Variable regularization factor(RF) is then employed to control the contribution made by the MD constraint in the cost function. Analysis results show that the RF can be taken as a combination of the step size and regularization parameter in the conventional NLMS. This implies that these parameters can be jointly controlled by simply tuning the RF as the proposed algorithm does. It also demonstrates that the RF can accelerate the convergence rate of the proposed algorithm and its optimal value can be obtained by minimizing the squared noise-free posteriori error. A method for automatically determining the value of the RF is also presented, which is free of any prior knowledge of the noise. While simulation results verify the analytical ones, it is also illustrated that the performance of the proposed algorithm is superior to the state-of-art ones in both the steady-state misalignment and the convergence rate. A novel algorithm is proposed to solve some problems. Simulation results show the effectiveness of the proposed algorithm.

关键词： adaptive filtering normalized least mean square (NLMS) minimum-disturbance (MD) constraint Variable regularization Variable step-size NLMS