测试软件启动口令的简单实现

介绍了一种基于LabWindowsCVI测试软件启动口令的实现方法。这种方法简单有效,具有一定的实际应用价值。同时,还对这一方法所存在的问题及解决办法作了阐述。     

A general framework for efficient geographic routing in wireless networks

We propose a new link metric called normalized advance (NADV) for geographic routing in multihop wireless networks. NADV selects neighbors with the optimal trade-off between proximity and link cost. Coupled with the local next hop decision in geographic routing, NADV enables an adaptive and efficient cost-aware routing strategy. Depending on the objective or message priority, applications can use the NADV framework to minimize various types of link cost.We present efficient methods for link cost estimation and perform detailed experiments in simulated environments. Our results show that NADV outperforms current schemes in many aspects: for example, in high noise environments with frequent packet losses, the use of NADV leads to 81% higher delivery ratio. When compared to centralized routing under certain settings, geographic routing using NADV finds paths whose cost is close to the optimum. We also conducted experiments in Emulab testbed and the results demonstrate that our proposed approach performs well in practice.     

Two hybrid differential evolution algorithms for engineering design optimization

This paper presents two hybrid differential evolution algorithms for optimizing engineering design problems. One hybrid algorithm enhances a basic differential evolution algorithm with a local search operator, i.e., random walk with direction exploitation, to strengthen the exploitation ability, while the other adding a second metaheuristic, i.e., harmony search, to cooperate with the differential evolution algorithm so as to produce the desirable synergetic effect. For comparison, the differential evolution algorithm that the two hybrids are based on is also implemented. All algorithms incorporate a generalized method to handle discrete variables and Deb's parameterless penalty method for handling constraints. Fourteen engineering design problems selected from different engineering fields are used for testing. The test results show that: (i) both hybrid algorithms overall outperform the differential evolution algorithms; (ii) among the two hybrid algorithms, the cooperative hybrid overall outperforms the other hybrid with local search; and (iii) the performance of proposed hybrid algorithms can be further improved with some effort of tuning the relevant parameters.     

Improved sensitivity analysis using a complex variable semi-analytical method

The semi-analytical method (SAM) is a computationally efficient and easy to implement approach often used for the sensitivity analysis of finite element models. However, it is known to exhibit serious inaccuracy for shape sensitivity analysis for structures modeled by beam, frame, plate, or shell elements. In the present paper, we use a semi-analytical approach based on complex variables (SACVM) to compute the sensitivity of finite element models composed of beam and plate elements. The SACVM combines the complex variable method (CVM) with the semi-analytical method (SAM) to obtain the response sensitivity accurately and efficiently. The current approach maintains the computational efficiency of the semi-analytical method but with higher accuracy. In addition, the current approach is insensitive to the choice of step size, a feature that simplifies its use in practical problems. The method is applicable to any structural elements including beam, frame, plate, or shell elements and only requires minor modifications to existing finite element codes.     

基于混合总线的虚拟仪器教学实验系统设计

针对自动测试、虚拟仪器及总线设备类课程的试验设备不足,在VXI、GPIB及LXI混合总线的基础上构建了一个虚拟仪器教学实验系统,并以C#.NET结合虚拟仪器技术建立了整个系统的软件架构;介绍了该系统的硬件软件设计方法及其实现的关键技术;通过课程实践表明,该系统功能强且扩展性好,满足了实验的要求,节约了实验成本。     

基于FPGA的电路板自动测试技术研究

军用电子装备中含FPGA器件的电路板的测试诊断一般采用边界扫描技术、Ⅵ曲线测试技术以及边界扫描和外部输入矢量相结合的方法;边界扫描技术无法进行外围器件的测试;Ⅵ曲线测试技术由于不能测试器件的逻辑功能及内部节点,故障覆盖率相对不高;边界扫描和外部输入矢量相结合的方法无法判断FPGA器件工作是否正常,因而不能完成整板功能的测试;综合应用ATE技术、VITAL标准和LASAR仿真技术,提出一种含FPGA器件电路板的自动测试思路,解决含FPGA器件电路板的自动测试问题.     

基于微波透射法测量织物含水率

织物的含水率是染整生产过程中的重要指标;应用微波技术检测织物的含水率,能在线实时准确测量,且可靠性好,抗干扰能力强,不易受到织物的颜色、结构等影响,并可检测织物内部的含水率,结果更具代表性;为了快速、准确地检测织物中的水分含量,基于微波透射法,设计了一套织物含水率在线检测系统,实现了对织物含水率在线无损检测;重点讨论微波测湿原理及方法,采用最小二乘法拟合直线,获得织物湿度与衰减量之间相互关系的标定曲线;实验结果表明;设计的装置可对含水率为30%～70%的织物进行有效的测量;测量精度高于士1%.     

纯音听力计中纯音信号发生器的设计与实现

纯音听力计是进行听觉功能测试的基本声学仪器,而纯音信号发生器是其最重要的组成模块,它决定着可控声源的质量,直接影响测试结果的准确性;文章分析了现有纯音信号发生器存在的问题,提出了一种基于微处理器ATMEG128的设计与实现方法;该发生器可生成频率在125Hz~8kHz、听力级为-10~120dB的精密纯音信号;其中,频率按1/3倍频程输出,听力级的最小调节精度可达0.5 dB,符合国家标准。     

电离层垂测仪系统信号源设计与实现

为了克服传统电离层垂测仪射频信号软件延时的缺点,提高大气电离层垂测仪系统信号源产生信号的精度,更充分地研究电离层物理特性,利用DDS技术和嵌入μC/OS-Ⅱ操作系统的miniARM微处理器,给出了一个新型的电离层垂测仪系统信号源的架构方案;该系统利用了32位ARM嵌入式微处理器LPC2220的定时器匹配硬件功能,控制DDS芯片Q2368完成无延时的相位调制;实验结果表明,该信号源所产生的高频信号具有精度高,频率转换时间短等特点,其他信号也完全满足电离层垂测仪对信号源的技术要求.     

基于MATLAB/VB的网络故障诊断软件设计

将VB调用Matlab的方法应用到基于神经网络的网络故障诊断系统软件的设计中;以VB编写诊断系统的主界面,利用ActiveX技术调用Matlab神经网络工具箱完成对网络故障的诊断,将两者的优势有机结合,从而缩短了程序开发周期,减少了程序员的工作量;该软件具有良好人机交互界面,便于网管人员的学习和掌握,且实例验证表明利用VB调用Matlab方法开发的网络故障诊断系统,其诊断结果可靠,能够满足网络实时故障诊断的要求.