Reduction of delayed optimal control problems to nondelayed problems

A method is exhibited which transforms a large class of optimal control problems with fixed delays to nondelayed problems, thus permitting classical results to be used in their analysis.     

On Brunovský's example

The example due to Brunovský [Eq. (1)] is analyzed, and further paradoxical properties are exhibited.     

合肥光源逐圈束流位置监测系统中的定时系统

 定时系统是合肥光源逐圈束流位置监测和相空间测量系统中的重要组成部分,其主要目的是为数据采集卡提供与环内电子束团同步的时钟信号。该系统包含高速ECL时钟成形、分频电路、程控延时电路、控制模块等部分。可实现延时范围0～220ns,最小延时步距0.5ns,调整精度0.1ns,时钟抖动小于200ps。系统控制软件基于客户/服务器结构,操作灵活、方便。     

Nonlinear Boundary Stabilization of Nonuniform Timoshenko Beam

In this paper, the stabilization problem of nonuniform Timoshenko beam by some nonlinear boundary feedback controls is considered. By virtue of nonlinear semigroup theory, energy-perturbed approach and exponential multiplier method, it is shown that the vibration of the beam under the proposed control actiondecays exponentially or in negative power of time t as t→∞.     

A queueing system with linear repeated attempts,bernoulli schedule and feedback

We analyse a single-server retrial queueing system with infinite buffer, Poisson arrivals, general distribution of service time and linear retrial policy. If an arriving customer finds the server occupied, he joins with probabilityp a retrial group (called orbit) and with complementary probabilityq a priority queue in order to be served. After the customer is served completely, he will decide either to return to the priority queue for another service with probability ϑ or to leave the system forever with probability =1−ϑ, where 0≤ϑ<1. We study the ergodicity of the embedded Markov chain, its stationary distribution function and the joint generating function of the number of customers in both groups in the steady-state regime. Moreover, we obtain the generating function of system size distribution, which generalizes the well-knownPollaczek-Khinchin formula. Also we obtain a stochastic decomposition law for our queueing system and as an application we study the asymptotic behaviour under high rate of retrials. The results agree with known special cases. Finally, we give numerical examples to illustrate the effect of the parameters on several performance characteristics.     

Langford系统Hopf分叉的线性反馈控制

分析Langford系统的Hopf分叉现象，并研究采用线性反馈控制方法控制该系统的Hopf分叉.从理论上推导出受控系统产生Hopf分叉的条件，给出了某些极限环的解析表达式，对该系统进行了分叉点的转移与极限环的稳定性控制.数值模拟说明本文采用的方法对Langford系统的Hopf分叉控制是有效的. 关键词： Langford系统 反馈控制 Hopf分叉 极限环     

双频氦氖激光回馈位移测量系统的实验与应用研究

研究了一种全新的纳米尺度位移测量系统。将双折射元件插入He-Ne激光器谐振腔内产生频率分裂效应，使原本单模谐振的激光器输出变成了频差可调的2个正交偏振频率（o光和e光），而形成双频激光器。在激光谐振腔外放置沿激光轴线位移的反射表面，将输出的激光束反射回腔内，以便对激光的光强进行调制，可实现高分辨率非接触式可判向位移测量。提出了一种细分方法，该方法突破了传统干涉系统的衍射极限（1/2波长）。对于633nm波长He-Ne激光，本系统的理想分辨率为1/8波长（约为79nm）。     

Gibbs光学双稳系统的状态反馈控制

基于稳定性理论,提出了一种状态反馈控制混沌的方法。介绍了该方法的控制原理以及各个预期的周期轨道反馈系数的选取原则。以Gibbs光学双稳系统为例,验证了该方法的有效性。数值结果表明,通过调节反馈系数,可以将系统控制在所需的目标轨道上。     

Detecting positive feedback in multivariate time series: The case of metal prices and US inflation

The objective of this paper is to examine causality and feedback relationships between primary commodity prices and US inflation. To this end, the bivariate noisy Mackey–Glass process recently developed by Kyrtsou and Labys [Evidence for chaotic dependence between US inflation and commodity prices, J. Macroecon. 28(1) (2006) 256–266] has been applied to assess this relationship. Results obtained support evidence in favour of causality, which can help to identify the influences of speculative price behaviour on inflation.