基于观测器的混沌系统的同步研究

提出了一类混沌系统的观测器同步方法.利用混沌系统的状态观测器，给出了一类混沌系统 观测器的同步的简单有效的方法，并分析了系统的稳定性，通过对Lorenz混沌系统的分析和 数值模拟研究，验证了该方法在混沌同步中的优良性能. 关键词： 混沌系统 混沌同步 状态观测器     

基于Lyapunov方程的分数阶新混沌系统的控制

新混沌系统是一种不同于Lorenz混沌系统、Chen混沌系统以及Liu混沌系统的新的三阶连续自治混沌系统.本文基于波特图的频域近似方法,提出了一种混合型电路单元来近似实现分数阶算子,并设计电路实现了2·7阶新混沌系统.基于Lyapunov方程的系统稳定性判定理论,设计了相应的控制器,实现了对分数阶新混沌系统的控制.     

保守系统的混沌控制

保守系统的混沌控制是一个重要而富有挑战性的研究课题。由于Liouville定理的限制和初始条件的特殊作用 ,使得适用于耗散系统的混沌控制方法不能直接用于保守系统。本文通过对耗散系统和保守系统混沌运动的特征进行分析和比较 ,阐述了保守系统混沌运动的规律 ,总结了近期研究过程中一些典型的基本理论和方法 ,综述了近年来保守系统混沌控制的相关进展和我们在保守系统的混沌控制方面所做的工作 ,并对保守系统混沌控制的应用和发展方向进行了展望。     

广义Birkhoff系统的两类广义梯度表示

提出了两类广义梯度系统, 即广义斜梯度系统以及具有对称负定矩阵的广义梯度系统. 分别讨论了这两类梯度系统与动力学系统稳定性的关系. 研究了广义Brikhoff系统的两类广义梯度表示, 分别给出条件和表达式. 给出了广义Brikhoff系统稳定性的梯度判别法, 利用广义梯度系统的性质来研究广义Birkhoff系统的稳定性. 并举例说明了方法的应用.     

Birkhoff系统的Hojman定理的几何基础

研究了Birkhoff系统的Hojman定理的几何基础.建立了系统的运动微分方程和Hojman守恒 定理，利用现代微分几何给出了Birkhoff系统的Hojman定理的一个证明. 关键词： Birkhoff系统 Hojman定理 对称性 微分几何     

一类切换混沌系统的实现

构建了一类可切换的三维自治混沌系统，通过系统选择器实现这类系统间的切换.这类系统都由七项组成，且都包含三项系统变量乘积的二次非线性项.详细地分析了这类三维系统平衡点的性质、混沌吸引子的相图和Lyapunov指数等特性，设计了实现这类可切换系统的实际电路并进行了电路实验. 关键词： 混沌系统 Lyapunov指数 切换     

激光偏振主动探测及成像系统的误差研究以及系统的改进

利用Mueller矩阵,以三种典型目标为模型,全面分析了主动偏振成像系统的误差来源。在实验系统典型参数下,对偏振度误差进行了模拟。提出了利用标准偏振度目标校准系统参数的方法,提高了实验系统的精度。以仿真结果为基础,对实验系统进行了进一步的改进。通过对实验元件参数和位置的合理配置,该实验系统能够提供高精度的目标偏振度探测。误差分析结果为偏振成像实验系统元件参数的选择提供了重要的参考依据,同时也为实验系统的改进提供了理论支持。     

一个基于Chen系统的新混沌系统的分析与同步

通过在Chen系统的第一个方程中加入一个可变系数的乘积项, 构造了一个新的三维自治混沌系统.新系统可通过调节其可变系数实现不同系数组合下系统的混沌产生或混沌抑制, 即调节该乘积项的可变系数, 可使不出现混沌的Chen系统产生混沌现象, 同时也可使产生混沌运动的Chen系统不再产生混沌现象.详细分析了新系统的特性, 研究了新系统的混沌同步问题, 并给出了相应的仿真结果.     

星间激光通信中复合轴系统的带宽设计研究

星间激光通信中,由粗跟踪系统和精跟踪系统组成的复合轴系统完成了系统的大范围、高精度跟踪任务。对复合轴系统进行了基于Z变换的数字模拟以研究其带宽设计。根据计算的卫星轨迹和粗跟踪系统机械误差,得到了粗跟踪系统的带宽设计结果;给出了粗跟踪系统和精跟踪系统的配合工作关系;得到了精跟踪系统的带宽设计结果;最后研究了在中高频扰动下,复合轴系统的带宽设计。以上结果为星间激光通信中的复合轴系统控制系统设计提供了重要依据。     

分数阶统一混沌系统的投影同步

改变系统参数计算了分数阶统一系统的最大Lyapunov指数和关联维数,研究了分数阶统一系统的动力学行为.基于线性系统的稳定判定准则,设计了一种同步方案,实现了分数阶统一混沌系统的投影同步.通过对分数阶Chen系统、分数阶Lü系统和分数阶类Lorenz系统投影同步的数值模拟,进一步验证了所提出方案的有效性.     

Bragg型声光双稳系统的调制效应

从理论上分析了Bragg型声光双稳系统的线性稳定性及调制效应.由系统的动力学方程、稳态方程出发,给出了出现双稳态的参数范围,并计算出稳区与非稳区的边界.对输入光作简谐调制时,预言了稳区输出光的共振效应和共振峰的偏移以及非稳区的频率锁定等现象.     

Real-Time Quantum Feedback Control: ManipulatingQuantum State in Non-Markovian System

In this paper, we propose a closed-loop real-time feedback design for manipulating a quantum state to a target eigenstate via sequential measurements. To this end, based on the Lyapunov stability theorem, considering the controllability and convergence of the system, we select one measured observable and two control channels, which feedback part of the output signal to the input end, forming a closed-loop control. By dynamical programming, we find the optimal parameters to achieve state transfer with a high probability by real-time feedback control. Numerical simulation experiments show that, in a stochastic quantum system with non-Markovian noise, the real-time control strategy moves the system from initial state to the target eigenstate with fast convergence.

     

Controlling cooperativity of a metastable open system coupled weakly to a noisy environment

The notion of cooperativity comprises a specific characteristic of a multipartite system concerning its ability to demonstrate a sigmoidal-type response of varying sensitivities to input stimuli in transitions between states under controlled conditions.From a statistical physics viewpoint,in this work we attempt to describe the cooperativity by the stability of a metastable open system with respect to irreversibility.To treat the evolution of a system weakly coupled to the environment in a kinetic framework,we consider two fluctuating energy levels of different dimensionalities,initial population of one level,reversible transitions of population between the levels,and irreversible depopulation of another level.An average is made over level fluctuations and environment vibrations so that an inter-level transition rate can be obtained accounting for the influences of external control on level position and dimensionality.It is found that the cooperativity of the two-level system is bounded approximately between 0.736 and unity,with the lower bound indicating worsening system stability.     

用于ICF驱动器的全LD泵浦高增益放大系统研究

四个LDA侧面泵浦的Nd3+YLF激光放大器构成的高增益放大系统,采用双通放大结构,有效抑制了自激辐射,具有较高的信噪比和能量转化效率,实现了对nJ量级注入脉冲的106以上的高增益放大,具有良好的近场分布与能量稳定性.对系统的工作特性进行了研究,实现了工程化设计,已成功应用于大型ICF驱动器的能量预放大级.     

Nonlinear modes in rotating double well potential with parity–time symmetry

We investigate the nonlinear modes in a rotating double well potential with 79T symmetry. Focus on the existence and stability of the nonlinear PT modes in this system, we found that five types of PT modes can stably exist by given certain parameter settings. The multistable area between these modes are studied numerically and the bistable and tristable areas are delimited. With different input trial wavefunctions, five types of solitary wave modes are identified. We found that the rotating of the potential can significantly affect the power flow of the fundamental harmonic mode, whose effect is absent for the other modes.     

Actuator saturation control of uncertain structures with input time delay

This paper presents a robust saturation control approach for active vibration attenuation of building structures involving parameter uncertainties and input time delay. The parameter uncertainties are described in both polytopic and norm-bounded forms and represent the variations of floor masses, stiffnesses and damping coefficients. The input time delay can be time-varying within a known bound. In terms of the feasibility of certain delay-dependent linear matrix inequalities (LMIs), a state feedback controller can be designed to guarantee the robust stability and performance of the closed-loop system in the presence of parameter uncertainties, actuator saturation, and input time delay. The effectiveness of the proposed approach is investigated by numerical simulations on the vibration control of a three-storey building structure subject to seismic excitation. It is validated that the designed robust saturation controller can effectively suppress the structural vibration and keep the system stability when there are parameter uncertainties and input time delay.     

Adaptive synchronization control of coupled chaotic neurons in an external electrical stimulation

In this paper we present a combined algorithm for the synchronization control of two gap junction coupled chaotic FitzHugh-Nagumo (FHN) neurons in an external electrical stimulation. The controller consists of a combination of dynamical sliding mode control and adaptive backstepping control. The combined algorithm yields an adaptive dynamical sliding mode control law which has the advantage over static sliding mode-based controllers of being chattering-free, i.e., a sufficiently smooth control input signal is generated. It is shown that the proposed control scheme can not only compensate for the system uncertainty, but also guarantee the stability of the synchronized error system. In addition, numerical simulations are also performed to demonstrate the effectiveness of the proposed adaptive controller.     

A novel robust proportional-integral （PI） adaptive observer design for chaos synchronization

In this paper, chaos synchronization in the presence of parameter uncertainty, observer gain perturbation and exogenous input disturbance is considered. A nonlinear non-fragile proportional-integral (PI) adaptive observer is designed for the synchronization of chaotic systems; its stability conditions based on the Lyapunov technique are derived. The observer proportional and integral gains, by converting the conditions into linear matrix inequality (LMI), are optimally selected from solutions that satisfy the observer stability conditions such that the effect of disturbance on the synchronization error becomes minimized. To show the effectiveness of the proposed method, simulation results for the synchronization of a Lorenz chaotic system with unknown parameters in the presence of an exogenous input disturbance and abrupt gain perturbation are reported.     

基于USB总线的离散量接口设计与实现

为了满足航空电子仿真系统对离散量输入输出控制的需求,设计开发了一种基于USB总线的离散量输入输出接口。该接口采用USB芯片CH375完成板卡与主机数据通信,51单片机作为主控制器,CPLD实现地址译码和逻辑控制,光耦和继电器分别为输入和输出隔离器件,具有采集56路光耦输入信号和56路继电器输出信号的功能。论文详细探讨了系统总体设计、硬件实现、软件配置和工作流程,给出了系统硬件的框架结构、软件架构,详细讨论了系统的驱动软件开发。该接口满足不同仿真系统离散量输入输出的需要,具有稳定性高、可热插拔、通道数目可变的特点,在工程应用中收到了很好的效果。     

Curvature instability in passive diffractive resonators

We study the stability of localized structures in a passive optical bistable system. We show that there is a critical value of the input field intensity above which localized structures are unstable with respect to a curvature instability. Beyond this instability boundary, a transition from the localized branch of solutions to stable hexagons is found.