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Adaptive recurrent-functional-link-network control for hypersonic vehicles with atmospheric disturbances

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Science china(Information Sciences) 2011年第3期54卷 482-497页

作者： DU YanLi 1, WU QingXian 2 , JIAng ChangSheng 2 & XUE YaLi 2 1 college of astronautics, nanjing university of aeronautics and astronautics, nanjing 210016, china 2.college of automation engineer.ng, nanjing university of aeronautics and astronautics, nanjing 210016, china college of astronautics Nanjing University of Aeronautics and Astronautics Nanjing China college of automation engineer.ng Nanjing University of Aeronautics and Astronautics Nanjing China

The controller design for a near-space hypersonic vehicle (NHV) is challenging due to its plant uncertainties and sensitivity to atmospheric disturbances such as gusts and turbulence. This paper first derives 12 states equations of NHVs subjected to variable wind field, and presents a novel recurrent neural network (RNN) control method for restraining atmospheric disturbances. The method devises a new B-spline recurrent functional link network (BRFLN) and combines it with the nonlinear generalized predictive control (ngPC) algorithm. Moreover, the proportional-derivative (PD) correction BRFLN is proposed to approximate atmo- spheric disturbances in flight. The weights of BRFLN are online tuned by the adaptive law based on Lyapunov stability theorem. Finally, simulation results show a satisfactory performance for the attitude tracking of the NHV in the mesosphere, and also illustrate the controller's robustness to wind turbulence.

关键词： near-space hypersonic vehicle atmospheric disturbances nonlinear predictive control adaptive control B-spline recurrent functional link network

A Raw Signal Simulator for Bistatic SAR

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Chinese Journal of aeronautics 2009年第4期22卷 434-443页

作者： Xia Weijie,Zhou Jianjiang college of Information Science and Technology,nanjing university of aeronautics and astronautics,nanjing 210016,china college of Information Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

This article proposes a new efficient raw signal simulator for the bistatic synthetic aperture radar （SAR） based on 2D fast Fourier transform （FFT） to deal with cases of both ideal trajectory and trajectory deviation. It begins with analyzing the geometric configuration and the range history of the bistatic SAR in side-looking and squint modes of ideal trajectory as well as trajectory deviation. Then a detailed and mathematical study is conducted on the equivalence relation of bistatic-to-monostatic applications （BTMA） in the case of ideal trajectory and trajectory deviation. Also a set of formulas are derived for the equivalence relation between bistatic SAR and monostatic SAR on some reasonable assumptions. Therefore, the application of the simulation method based on the 2D FFT for the monostatic SAR can be extended to the case of bistatic SAR. Finally, the simulation results prove the validity of this method. By comparing the efficiency of the proposed method with that of the time domain method, it is shown that the former is a few orders of magnitude higher.

关键词： bistatic synthetic aperture radar raw signal simulation fast Fourier transform

Three vortex motion in the slightly viscous flow

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 735-744页

作者： ZHU Hao & CHEng KeMing college of Aerospace engineer.ng, nanjing university of aeronautics and astronautics, nanjing 210016, china college of Aerospace engineer.ng Nanjing University of Aeronautics and Astronautics Nanjing China

The dynamics of three vortices moving in an ideal fluid in a plane can be expressed in Hamiltonian form. However, when viscosity can not be ignored, the system of point vortices has not this delicious structure. This investigation focuses on the viscosity effect on the motion of three vortices. Since the viscous diffusion of vortices is simulated by Brownian motion, the equations of intervortical distances are obtained by Ito formula. These equations show that there exist two viscosity effects on intervortical distances: stable expansion and random impulse. Furthermore, via employing the asymptotic solution to these equations, these two viscous effects have been shown to destroy the self-similar process of collapse and make it into a new configuration, which is similar to the near collapse in the ideal case.

关键词： point vortex slightly viscous flow Fokker-Planck equation collapse Ito formula

Resolution method for overlapping peaks based on the fractional-order differential

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Science china Chemistry 2007年第6期50卷 797-805页

作者： LI YuanLu1, YU ShengLin2 & ZHEng Gang2 1 college of Information & Control, nanjing university of Information Science & Technology, nanjing 210044, china 2.college of automation engineer.ng, nanjing university of aeronautics and astronautics, nanjing 210016, china college of Information & Control Nanjing University of Information Science & Technology Nanjing China college of automation engineer.ng Nanjing University of Aeronautics and Astronautics Nanjing China

Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at different orders. Also, equations between the differential order and the zero-crossing of the fractional-order differential of the specified peak signals are proposed according to the variation of the zero-crossing of the specified peak signals at different orders. Characteristic paramters of the Gaus- sian peak, Lorentzian peak, and Tsallis peak can be estimated using estimator I and estimator II which are obtained by the equations above. As a result, a new method is presented to resolve the overlapped peaks signal. Firstly, a fractional-order differential of the specified peak signals is obtained with the fractional-order differentiation filter. Then, characteristic paramters of the specified peak signals can be extracted using estimator I and estimator II. Finally, the Tsallis peak is used as a model to assign the overlapping peak signals correctly. Experimental results show that the proposed method is efficient and effective for the simulated overlapping peaks and detected overlapping voltammetric peak signals.

关键词： fractional-order differentiation filter, fractional-order differential, overlapping peaks, voltammetric peak

Online-SVR-compensated nonlinear generalized predictive control for hypersonic vehicles

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Science china(Information Sciences) 2011年第3期54卷 551-562页

作者： CHEng Lu , JIAng Chang Sheng & PU Ming college of automation engineer.ng, nanjing university of aeronautics and astronautics, nanjing 210016, china college of automation engineer.ng Nanjing University of Aeronautics and Astronautics Nanjing China

This paper is concerned with the problem of hypersonic vehicle (HSV) attitude control system in uncertain flight conditions. The problem can be expressed as the adaptive robust control for a class of uncertain nonlinear systems. Based on the description of the aerodynamic structure and the model of flight control system of a certain kind of HSV, the ideal nonlinear generalized predictive control (ngPC) law based on uncertain nonlinear model is raised first to optimize the receding-horizon criterion of tracking errors. Then the online support vector regression (SVR) is employed to identify the uncertain item in the ideal control law. It is the compensating part of the controller. In addition, the stability of the close-loop system is analyzed using the Lyapunov method. The developed control strategy is well-implemented in this HSV attitude control system, and the simulation results compared with both nominal ngPC and RBF neural network disturbance observer show the good robustness and disturbance attenuation ability of this strategy and demonstrate the efficiency of online SVR algorithm.

关键词： hypersonic vehicle flight control nonlinear generalized predictive control online support vector regression

Partial discharge-induced crack growth in dielectric materials

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Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 886-891页

作者： LUO JiaCheng,GAO CunFa & DAI XiangHua college of Aerospace engineer.ng,nanjing university of aeronautics & astronautics,nanjing 210016,china college of Aerospace engineer.ng Nanjing University of Aeronautics & Astronautics Nanjing China

Partial discharge(PD) of an air-filled semi-permeable crack in a dielectric material is studied based on the streamer-type discharge mechanism to explore the effects of applied mechanical-electric fields on crack *** the frame of two-dimensional deformation,the electric field inside the crack is first derived by taking the crack deformation into ***,the effects of electric field before PD are discussed through considering the contribution of the induced electric field inside the deformed crack space to the total energy release ***,PD and its effects on crack growth are *** is found that:(1) before PD,the applied electric field always retards crack growth;(2) during PD,the applied electric field can induce crack growth in dielectric materials.

关键词： crack dielectric materials partial discharge electric field effects

Modal identification based on Hilbert-Huang Transform of structural response with S VD preprocessing

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Acta Mechanica Sinica 2009年第6期25卷 883-888页

作者： Min Zheng Fan Shen Yuping Dou Xiaoyan Yan college of Civil Aviation,nanjing university of aeronautics and astronautics,210016 nanjing. china college of Civil Aviation Nanjing University of Aeronautics and Astronautics Nanjing China

In recent years, Empirical mode decomposition and Hilbert spectral analysis have been combined to identify system parameters. Singular-Value Decomposition is pro- posed as a signal preprocessing technique of Hilbert-Huang Transform to extract modal parameters for closely spaced modes and low-energy components. The proposed method is applied to a simulated airplane model built in Automatic Dynamic Analysis of Mechanical Systems software. The results demonstrate that the identified modal parameters are in good agreement with the baseline model.

关键词： Modal identification . Hilbert-Huang Transforms - Singular-value decomposition . Signal processing

Robust adaptive backstepping control for a class of uncertain nonlinear systems based on disturbance observers

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Science china(Information Sciences) 2010年第6期53卷 1201-1215页

作者： MEI Rong 1,2, WU QingXian 1 & JIAng ChangSheng 1 1 automation college, nanjing university of aeronautics and astronautics, nanjing 210016, china 2 Criminal Investigation Department, nanjing Forest Police college, nanjing 210042, china automation college Nanjing University of Aeronautics and Astronautics Nanjing China Criminal Investigation Department Nanjing Forest Police College Nanjing China

In this paper, a novel robust adaptive control scheme for a class of uncertain nonlinear systems is proposed using disturbance observer and backstepping ***, a disturbance observer is developed using radial basis function(RBF) neural *** parameter updated law of the RBF neural network is given for monitoring subsystem disturbance *** robust adaptive control scheme is then presented with backstepping method based on the designed disturbance *** uniform ultimate boundedness(SGUUB) of all signals in the closed-loop uncertain nonlinear system is *** closed-loop system stability analysis shows that semiglobal uniform boundedness of all signals is guaranteed by appropriately choosing design ***, two examples are taken to illustrate the effectiveness of the proposed control scheme.

关键词： uncertain nonlinear systems disturbance observer RBF neural network backstepping control robust adaptive control

On the general expressions of finite Hankel transform

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2125-2130页

作者： JIAng Quan 1,2 & GAO CunFa 1 1 college of Aerospace engineer.ng,nanjing university of aeronautics and astronautics,nanjing 210016,china 2 School of Civil engineer.ng,Nantong university,Nantong 226019,china college of Aerospace engineer.ng Nanjing University of Aeronautics and Astronautics Nanjing China School of Civil engineer.ng Nantong University Nantong China

The general expressions of finite Hankel transform are naturally deduced with the help of the property of Bessel *** equations in this paper can degenerate into three kinds of boundaries since all the coefficients in the boundary conditions are taken into *** results can be adopted in solving physics problems involving the finite Hankel transform.

关键词： hankel transform bessel function finite integral