An adaptive tracking problem for a family of retarded time-delay plants

Most of the existing switching control techniques are developed specifically for finite-dimensional linear time-invariant (LTI) systems. In many practical applications, however, it is essential to take time delay into consideration in the modelling as the control system can be highly sensitive to delay. In this paper, a multi-model switching control algorithm is proposed for retarded time-delay systems. It is assumed that the plant is represented by a family of known multi-input multi-output, observable, LTI models with multiple delays in the states, and that corresponding to each model in the known family, there exists a high-performance finite-dimensional LTI controller. In addition, it is supposed that a bound on the magnitude of the external inputs and disturbances is available. It is then shown that the proposed switching controller can stabilize the uncertain system, and that under some mild conditions, output tracking can be achieved in the given problem setting. Copyright © 2007 John Wiley & Sons, Ltd.     

自适应电子镇流器控制器IR2520原理及应用

IR2520是自适应镇流器控制器与600V半桥驱动器单片IC ,可用来驱动半桥配置中的荧光灯。文中介绍了IR2520的主要特点和基本原理 ,给出了它的典型应用电路。     

基于可重构FPGA技术的自适应FIR滤波器的实现

有限冲激响应(FIR)滤波器设计遇到的难题是滤波要进行大量乘法运算,即使是在全定制的专用集成电路中也会导致过大的面积与功耗.对于用硬件实现系数是常量的专用滤波器,可以通过分解系数变为应用加、减和移位而实现乘法.FIR滤波器的复杂性主要由用于系数乘法的加法器/减法器的数量决定.而对于自适应FIR滤波器,大多数场合下可用数字信号处理器(DSP)或CPU通过软件编程的方法来实现,但是对于要求高速运算的场合,VLSI实现是很好的选择.基于这一考虑,可以用符号数的正则表示(CSD)码表示系数, 再利用可重构现场可编程门阵列(FPGA)技术实现.可重构结构的应用,能保证系统的其余部分同时处于运行状态时实现FIR滤波器系数的更新.文中利用CSD码和可重构思想,提出了用FPGA实现自适应FIR滤波器的一种方案.     

250W带功率因数校正整流电源模块的研制

功率因数校正技术越来越成为电源行业研究的热点。文中介绍了适用于雷达等设备的250W带功率因数校正整流电源模块的设计，分析了其中升压电感器设计、主开关管保护、控制电路消振、散热设计和表面贴装等关键技术，完成了实验研究，获得了满意的试验结果。     

信道粒度可变的分块自适应OFDM传输系统

满足不同服务质量(QoS)业务是Beyond 3G系统必须考虑的一个问题。本文提出一种可变信道粒度的分块自适应OFDM系统。系统能够根据不同用户多样化的速率需求，自适应地改变分块的大小，并且在每个分块上进行自适应调制，在满足用户速率要求的基础上降低了对子载波分配信息(SAI)和自适应调制信息(AMI)的需求。仿真结果表明，本文提出的系统在系统容量和频谱效率上比固定分块自适应OFDM系统有更好的性能。     

一种基于TV模型的自适应图像修复方法

图像修复是数字图像处理的重要内容，可用于被损坏的图像和视频修复、视频文字去除以及视频错误隐藏等。基于TV模型的修复方法有较好的恢复效果，但对参数的选取比较敏感，且运算量较大。本文提出了一种基于TV模型的自适应图像修复方法，与原方法相比可以有效提高该算法的稳健性，并能显著的减少运算时间。     

New developments in CdTe and CdZnTe detectors for X and γ-ray applications

There has been considerable recent progress in II-VI semiconductor material and in methods for improving performance of the associated radiation detectors. New high resistivity CdZnTe material, new contact technologies, new detector structures, new electronic correction methods have opened the field of nuclear and x-ray imaging for industrial and medical applications. The purpose of this paper is to review new developments in several of these fields. In addition, we will present some recent results at LETI concerning first the CdTe 2-D imaging system (20 × 30 mm² with 400 × 600 pixels) for dental radiology and second the CdZnTe fast pulse correction method applied to a 5 × 5 × 5 mm³ CdZnTe detector (energy resolution = 5% for detection efficiency of 85% at 122 keV) for medical imaging.     

Adaptive control of siso plants with unmodelled dynamics

In this paper we pursue a twofold aim. First we want to simplify the complexity of the classical Monopoli's scheme, the so-called ‘Augmented error signal control scheme’. Then we also wish to cope with the realistic situation in which the presence of unmodelled dynamics has to be taken into account. This latter problem has been faced in the literature by suitably modifying the adaptation mechanism in order to avoid undesired phenomena as well as to obtain an attractive stability region for the state trajectories starting from any point in a predefined initial condition set. In our case the necessity of introducing any sort of modification in the adaptation mechanism is completely avoided, but we still obtain asymptotic stability of the output error signal.     

掺气减蚀设施水力计算的改进

结合小湾工程泄洪洞模型试验进行了11种挑跌坎型和6级流量的试验观测，据此提出了特别适用于大单流量条件的射流出射角修正式，提出了射流近底流速的选取原则.与实验资料对比证明本文计算方法有足够精度。