基于ARM和FPGA的高扩展性超声检测模块设计与实现

介绍了一种以ARM和FPGA联合作为中央控制处理单元的4路超声探伤模块。给出了其整体结构方案,阐述了以4路超声模拟信号为一组的多路超声探伤模块硬件扩展的设计思路和实现方案,讨论了FPGA对高速LVDS数据的采集、处理、时序同步功能的实现,ARM与FPGA之间总线接口的实现,ARM嵌入式系统功能以及网络通信功能的实现。实际应用表明,该功能模块能达到预期的设计要求,并能方便地实现硬件扩展。     

基于贝叶斯最小错误率的一种新的指纹分割算法

指纹图像分割是自动指纹识别系统中非常重要的一步。本文介绍了一种新的基于贝叶斯最小错误率的指纹分割方法。首先,提出了一种新的基于方向信息的分割特征。然后,具体介绍了基于这种特征的分割算法。最后根据最小错误率的贝叶斯决策确定合适的阈值割除背景区域。这种方法在FVC2000指纹库中进行了测试,实验结果证明了它的有效性。     

汽车运行状态图像记录仪的研制

本文采用S3C2440A单片机研制了汽车运行状态图像记录仪,并设计了其硬件开发了其软件。该纪录仪采用JPEG算法进行图像压缩,FAT格式进行图像存储,能够实时记录汽车运行时的图像,通过对图像的回放实现了解汽车的运行历史状态,交通事故的判定等功能。     

Adaptive backstepping control of a class of uncertain nonlinear systems with unknown backlash-like hysteresis

In this note, we consider the same class of systems as in a previous paper, i.e., a class of uncertain dynamic nonlinear systems preceded by unknown backlash-like hysteresis nonlinearities, where the hysteresis is modeled by a differential equation, in the presence of bounded external disturbances. By using backstepping technique, robust adaptive backstepping control algorithms are developed. Unlike some existing control schemes for systems with hysteresis, the developed backstepping controllers do not require the uncertain parameters within known intervals. Also, no knowledge is assumed on the bound of the "disturbance-like" term, a combination of the external disturbances and a term separated from the hysteresis model. It is shown that the proposed controllers not only can guarantee global stability, but also transient performance.     

Adaptive backstepping control of uncertain systems with unknown input time-delay

In this paper, we establish the robustness of adaptive controllers designed using the standard backstepping technique with respect to unmodeled dynamics involving unknown input time delay. While noting that some results on robust stabilization of non-minimum phase systems using the backstepping technique are available, we realize that the standard adaptive backstepping technique has only been shown applicable to unknown minimum phase systems. Another significance of our result is to enable the class of systems stablizable by adaptive backstepping controllers to cross the boundary of minimum phase systems, since systems with input time delay belong to non-minimum phase systems. Moreover, the L₂ and L_∞ norms of the system output are also established as functions of design parameters. This implies that the transient system performance can be adjusted by choosing suitable design parameters.     

基于改进的BP神经网络入侵检测方法研究

针对遗传算法局部搜索能力弱和收敛速度慢,在选择操作之后加上了禁忌搜索算法,并对交叉操作进行改进,最后用禁忌搜索作为变异操作,从而加快算法的收敛速度,并用此改进的遗传算法来优化BP神经网络的权值。实验证明,采用该方法优化BP神经网络权值,能克服BP神经网络收敛速度慢、局部极小问题。     

基于国半LM3886的高保真合并式音频功率放大器

顺应当前节能减排的原则,开发了一款性价比极高、性能较完善的基干国半LM3886的高保真合并式音频功率放大器,该合并武音频功率放大器能匹配绝大多数书架音箱.实测指标与实际试听都达到较高水平.     

RTD/HEMT单片集成中RTD直流参数与材料结构的关系

为了研究器件参数与材料结构的关系,设计了三种不同的GaAs基RTD材料结构。通过完全相同的器件制造工艺,研制出三种RTD器件,并测量了它们的9个直流参数。对测量结果进行了对比和分析。最后针对RTD与HEMT集成时,如何处理RTD与HEMT间的电流匹配问题提出了建议。     

A new chaotic secure communication system

The paper proposes a digital chaotic secure communication by introducing a magnifying glass concept, which is used to enlarge and observe minor parameter mismatch so as to increase the sensitivity of the system. The encryption method is based on a one-time pad encryption scheme, where the random key sequence is replaced by a chaotic sequence generated via a Chua's circuit. We make use of an impulsive control strategy to synchronize two identical chaotic systems embedded in the encryptor and the decryptor, respectively. The lengths of impulsive intervals are piecewise constant and, as a result, the security of the system is further improved. Moreover, with the given parameters of the chaotic system and the impulsive control law, an estimate of the synchronization time is derived. The proposed cryptosystem is shown to be very sensitive to parameter mismatch and hence the security of the chaotic secure communication system is greatly enhanced.     

地面防空作战的多导弹-单目标信息对抗模型与仿真研究

在地面防空作战中，地空导弹和空中目标的对抗是一个动态的对抗过程。通过把模型分为自身状态和对敌方的估计状态，建立了防空作战多导弹－单目标的对抗模型，分析了不同阵地的导弹追击和目标逃避时的控制输入选择原则。通过仿真，得到了较好的结论，体现了导弹和目标之间的对抗性，对深入研究地面防空系统对抗性建模方法具有一定意义。