分布式光纤中的稳健时间延迟估计方法

在分布式光纤传感系统定位中,传统时延估计算法常由于噪声相关性较强而失效。采用一种削弱相关噪声的改进型广义相关法,并针对系统特点,为进一步改善分布式光纤传感定位的准确度与稳定度,提出了一种先对数据按事件信号进行分帧,再采用卡尔曼滤波器对分帧时延估计结果进行跟踪的时延估计方案。系统仿真实验与实际数据测试结果均表明:提出的时延估计方案能够有效抑制强相关性的噪声,提高时延估计的准确度与稳定度。经大量现场测试,本文的方案能够有效地将时延估计误差稳定地控制在0.2个采样间隔以内,能够满足系统实际定位精度要求。     

随机基因选择模型中的延迟效应

研究了噪声驱动的基因选择模型中的延迟效应. 据小延迟方法和随机等价法则得到相应的延迟Fokker-Planck方程, 给出稳态概率分布函数的近似表达式. 分析了在噪声驱动下, 延迟时间对系统稳态性质的影响. 结果表明: 延迟时间可以诱导系统从单稳态向双稳态转化, 发生相变; 在基因选择过程中, 延迟时间有利于从基因群体中选择出某一单倍体基因. 数值模拟结果与理论预测基本符合.     

利用短期心脏记忆消除螺旋波和时空混沌

在Luo-Rudy的心脏模型中引入了记忆效应, 该记忆效应表现为膜间电压的延迟耦合. 研究了记忆效应对螺旋波的影响, 数值模拟结果表明:心脏记忆可导致螺旋波无规则漫游;当延迟时间适当选取时, 增加记忆强度会导致螺旋波的频率减小, 如果记忆强度超过临界值, 心脏记忆效应还可以使螺旋波和时空混沌消失, 因为含时外行钾离子电流被心脏记忆过度抑制.     

Method to identify time delay of chaotic semiconductor laser with optical feedback

We propose a power spectrum analysis method to directly identify the time delay of a chaotic semiconductorlaser with optical feedback. By measuring the radio frequency (RF) power spectrum of the chaotic laserand performing an inverse Fourier transform, we can easily unveil all the time delay signatures, regardless ofwhether the chaotic output is induced by single or multiple feedback. This method successfully retrieves thetwo time delay signatures from the power spectrum of a semiconductor laser with double-cavity feedback.     

数字域时间延迟积分时间CMOS相机高分“凝视”成像设计分析

为实现凝视卫星高分跟踪成像,设计了数字域时间延迟积分(TDI)互补金属氧化物半导体(CMOS)传感器在凝视姿态下的成像匹配模型,推导了卫星凝视跟踪成像时相对轨道坐标系的姿态变化,采用坐标变换方法实时计算其在凝视过程中随姿态变化的行转移时间,利用蒙特卡罗方法统计计算了凝视模式下姿态指向精度和稳定度对成像的影响。利用数字域TDI CMOS原理样机和小卫星姿态控制系统全物理仿真平台对成像进行了仿真分析。结果表明,卫星的姿态控制精度在成像过程中会引起纵向的像移速度失配和横向匹配的残余像移,成像积分级数越高,图像信噪比越大。积分级数的增加对卫星姿态提出较高要求,仿真平台姿态角和姿态角速度控制精度分别优于0.05°,0.005°/s时,采用积分级数为48级能较好地满足成像质量要求。     

A new reduction-based LQ control for dynamic systems with a slowly time-varying delay

Time delays in the feedback control often dete- riorate the control performance or even cause the instability of a dynamic system. This paper presents a control strategy for the dynamic system with a constant or a slowly time-varying input delay based on a transformation, which sire-plifies the time-delay system the relation is discussed for into a delay-free one. Firstly, two existing reduction-based linear quadratic controls. One is continuous and the other is discrete. By extending the relation, a new reduction-based control is then developed with a numerical algorithm presented for practical control implementation. The controller suggested by the proposed method has such a promising property that it can be used for the cases of different values of an input time delay without redesign of controller. This property provides the potential for stabilizing the dynamic system with a time-varying input delay. Consequently, the application of the proposed method to the dynamic system with a slowly time-varying delay is discussed. Finally, numerical simulations are given to show the efficacy and the applicability of the method.     

ACTIVE CONTROL OF A FLEXIBLE CANTILEVER PLATE WITH MULTIPLE TIME DELAYS

Active control of a flexible cantilever plate with multiple time delays is investigated using the discrete optimal control method. A controller with multiple time delays is presented. In this controller, time delay effect is incorporated in the mathematical model of the dynamic system throughout the control design and no approximations and assumptions are made in the controller derivation, so the system stability is easily guaranteed. Furthermore, this controller is available for both small time delays and large time delays. The feasibility and efficiency of the proposed controller are verified through numerical simulations in the end of this paper.     

Controlling a time-delay system using multiple delay feedback control

In this paper multiple delay feedback control (MDFC) with different and independent delay times is shown to be an efficient method for stabilizing fixed points in finite-dimensional dynamical systems. Whether MDFC can be applied to infinite-dimensional systems has been an open question. In this paper we find that for infinite-dimensional systems modelled by delay differential equations, MDFC works well for stabilizing (unstable) steady states in long-, moderate- and short-time delay regions, in particular for the hyperchaotic case.     

TDI CCD成像系统的研究

采用IL E2TDICCD作为传感器 ,与计算机构成了成像系统 ,并在计算机CRT上显示出图像。解决了CCD的时序电路及功率驱动电路设计问题。采用相关双采样技术滤除CCD输出信号复位噪声 ,提高了视频信号的信噪比。CCD的数据传送速度达到 10MHz ,行扫描速度达到 3.5kHz。     

智能型高速CCD相机的时序电路的研制

首先详细地介绍了几种传统时序电路的实现方法与各自存在的优缺点 ,然后对 isp L SI器件的性能特点以及 TDI- CCD相机的组成结构、工作原理进行了简要地阐述 ,最后对采用 isp L SI器件实现 CCD相机时序电路的全过程进行了全面、细致地分析。本文结合实际课题 ,已由在线可编程大规模逻辑器件实现了高速 TDI- CCD相机的时序电路。此相机系统具有一些重要参数 (行周期、TDI级数、视频信号的增益、偏置参数 ) ,并可以灵活控制。同时该系统又具有高可靠性、高稳定性、低功耗等特点。