Response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control

We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.     

A minimax optimal control strategy for uncertain quasi-Hamiltonian systems

A minimax optimal control strategy for quasi-Hamiltonian systems with bounded parametric and/or external disturbances is proposed based on the stochastic averaging method and stochastic differential game. To conduct the system energy control, the partially averaged Ito stochastic differential equations for the energy processes are first derived by using the stochastic averaging method for quasi-Hamiltonian systems. Combining the above equations with an appropriate performance index, the proposed strategy is searching for an optimal worst-case controller by solving a stochastic differential game problem. The worst-case disturbances and the optimal controls are obtained by solving a Hamilton-Jacobi-Isaacs （HJI） equation. Numerical results for a controlled and stochastically excited DulTlng oscillator with uncertain disturbances exhibit the efficacy of the proposed control strategy.     

负反馈控制混沌系统的实现

永磁同步电动机在一定工作情况下将呈现混沌运动,这种现象可能是有害的.该文采用负反馈控制方法对永磁同步电动机混沌模型进行控制,将系统控制到指定的平衡态.详细介绍了应用Maflab编程求解方程和数值仿真的结果,以此证明了此控制简单有效.     

On stochastic optimal control of partially observable nonlinear quasi Hamiltonian systems

A stochastic optimal control strategy for partially observable nonlinear quasi Hamiltonian systems is proposed.The optimal control forces consist of two parts. The first part is determined by the conditions under which the stochastic optimal control problem of a partially observable nonlinear system is converted into that of a completely observable linear system. The second part is determined by solving the dynamical programming equation derived by applying the stochastic averaging method and stochastic dynamical programming principle to the completely observable linear control system. The response of the optimally controlled quasi Hamiltonian system is predicted by solving the averaged Fokker-Planck-Kolmogorov equation associated with the optimally controlled completely observable linear system and solving the Riccati equation for the estimated error of system states. An example is given to illustrate the procedure and effectiveness of the proposed control strategy.     

On stochastic optimal control of partially observable nonlinear quasi Hamiltonian systems

INTRODUCTION Since many actual control systems such asthose in structural engineering are subjected torandom excitations and the system states are esti-mated from measurements with random noise,stochastic optimal control of partially observablesystems is a research subject of much significance.One basic approach to this problem is to convert itinto the stochastic optimal control of completelyobservable systems using separation theorem(Wonham, 1968; Fleming and Rishel, 1975; Ben-so…     

Nonlinear stochastic optimal bounded control of hysteretic systems with actuator saturation

A modified nonlinear stochastic optimal bounded control strategy for random excited hysteretic systems with actuator saturation is proposed. First, a controlled hysteretic system is converted into an equivalent nonlinear nonhysteretic stochastic system. Then, the partially averaged Itoe stochastic differential equation and dynamical programming equation are established, respectively, by using the stochastic averaging method for quasi non-integrable Hamiltonian systems and stochastic dynamical programming principle, from which the optimal control law consisting of optimal unbounded control and bang-bang control is derived. Finally, the response of optimally controlled system is predicted by solving the Fokker-Planck-Kolmogorov （FPK） equation associated with the fully averaged Itoe equation. Numerical results show that the proposed control strategy has high control effectiveness and efficiency.     

差分“食物有限”反馈控制生态系统持久性的一个注记

研究具有反馈控制变量的时滞离散单种群模型的持久性问题,得到了一组新的保证该系统持久的充分性条件.所得结果实质性的改进了吴丽萍[具有反馈控制和时滞的＂食物有限＂离散种群模型的持久性]一文的主要结果.     

捕食者具有反馈控制的Leslie-Gower捕食-食饵模型的稳定性研究

研究一类捕食者具有反馈控制的Leslie-Gower捕食食饵模型,通过构造Lyapunov函数方法,可以得到系统的唯一正平衡点是全局稳定的结论.这表明反馈控制变量只改变平衡点的位置-捕食者密度增加而食饵密度降低,但不会改变系统的稳定性态.     

一类具有反馈控制和反应扩散的Logistic种群模型的全局稳定性

研究一类具有反馈控制和反应扩散的Logistic种群模型,通过构造适当的Lyapunov函数,得到了该生态种群系统的正平衡点是全局渐近稳定的,所得结论表明扩散对该生态种群系统正平衡点的稳定性没有影响。     

Optimal state feedback control of brushless direct-current motor drive systems based on Lyapunov stability criterion

This paper develops a unified methodology for a real-time speed control of brushless direct-current motor drive systems in the presence of measurement noise and load torque disturbance. First, the mathematical model and hardware structure of system is established. Next, an optimal state feed back controller using the Kalman filter state estimation technique is derived. This is followed by an adaptive control algorithm to compensate for the effects of noise and disturbance. Those two algorithms working together can provide a very-high-speed regulation and dynamic response over a wide range of operating conditions. Simulated responses are presented to highlight the effectiveness of the proposed control strategy.     

基于变周期采样模型的网络控制系统的随机最优状态反馈控制

本文研究变周期采样的网络控制系统模型的随机最优反馈控制。假设网络诱导延时服从某一个区间的均匀分布,设计一个依赖延时的状态反馈控制器,使得所建立的变周期采样的NCS模型指数均方稳定。利用动态规划思想结合Bellman方程通过优化所给定的性能指标,得到了随机最优反馈控制器设计方法,并通过仿真实例验证了本章提出方法的有效性。     

基于电控发动机氧传感器闭环反馈机制的研究

通过对电控汽油机燃油反馈系统中起关键作用的氧传感器的故障实验,在不同工作条件下,研究氧传感器正常工作或模拟失效时对汽油机的各项运行参数及排放物的影响。通过对实验结果的统计与分析,提出基于氧传感器的燃油反馈系统在电控汽油机不同运行阶段的控制方法和控制策略。     

具有反馈控制和时滞的"食物有限"离散种群模型的持久性

研究了具有反馈控制和时滞的“食物有限”离散种群模型： {N（n＋1）=N（n）exp{r（n）[k（n）-N（n-m）/k（n）＋λ（n）N（n-m）-d（n）μ（n）]} △μ（n）=-a（n）μ（n）＋b（n）N（n-m）},得到了保证该系统永久持续生存的充分条件．     

论武术教学中的反馈联系

在武术教学中,教师利用武术教学时,所掌握的信息（即刻反馈信息和滞后反馈信息）,对武术教学进行信息处理。通过学生学习武术动作时的同步反馈信息,在武术课教学中即刻进行反馈信息的处理,帮助学生学习提高武术动作和套路动作技能;再利用学生学习武术后的滞后反馈信息进行统计分析,来修订武术学科教学计划和武术学科课时计划。更好地完善武术学科的教学。     

Effects of simultaneous auditory feedback on reading accuracy during reading development

Five groups of twelve right-handed male children from the second to the sixth grade with normal reading efficiency were tested under three conditions of simultaneous amplified auditory feedback, binaurally, to the left and to the right ear, on reading aboud two separate classes of words, nouns and nonwords. Lateralized feedback was supposed to shift auditory attention towards the source of input and modify as a consequence, the functionality of the contralateral hemisphere. Right ear feedback improved reading accuracy with respect to the control (binaural) or left ear condition in the first three grades. No effect was observed in the fifth grade whereas in the sixth grade, the condition of left ear feedback improved only the reading of nouns. Changes in reading accuracy are interpreted according to an hypothesis of a decrement of the left hemisphere involvement during the course of reading development. These changes are discussed in relation to Frith's (1985) psycholinguistic model of reading acquisition.     

Quantitative feedback theory and zero phase error tracking control combined robust control for radar truck leveling simulator

Radar leveling system is the key equipment for improving the radar mobility and survival capability. A combined quantitative feedback theory(QFT)controller is designed for the radar truck leveling simulator in this paper, which suffers from strong nonlinearities and system parameter uncertainties. QFT can reduce the plant uncertainties and stabilize the system, but it fails to obtain high-precision tracking. This drawback can be solved by a robust QFT control scheme based on zero phase error tracking control(ZPETC)compensation. The combined controller not only possesses high robustness, but greatly improves the system performance. To verify the effectiveness and the potential of the proposed controller, a series of experiments have been carried out. Experimental results have demonstrated its robustness against a large range of parameters variation and high tracking precision performance, as well as its capability of restraining the load coupling among channels. The combined QFT controller can drive the radar truck leveling platform accurately, quickly and stably.     

On the stochastic dynamics of molecular conformation

An important functioning mechanism of biological macromolecules is the transition between different conformed states due to thermal fluctuation. In the present paper,a biological macromolecule is modeled as two strands with side chains facing each other,and its stochastic dynamics including the statistics of stationary motion and the statistics of conformational transition is studied by using the stochastic averaging method for quasi Hamiltonian systems. The theoretical results are confirmed with the results from Monte Carlo simulation.     

反馈调节在技术基础课教学中的运用

该文从《液压传动》这门工程机械类各专业重要的技术基础课的特点出发,论述了运用反馈调节的教学法是行之有效的.在具体操作中,则要处理好突出重点、循序渐进、深入浅出、前后呼应、环节配合这五个方面的问题.     

串联负反馈放大器基本放大倍数Ao的计算方法问题

分析了串联负反馈放大器基本放大倍数Ao两种计算方法的差异,证明了负反馈作用会掩盖理论计算和实验测量Ao产生的误差.     

反馈极性的基础理论研究

文章用方框图明确了输入信号、反馈信号等概念 ,分析了反馈极性的决定因素和直接效果 ,改进了传统的“瞬时极性法”。