On the eigenvalues and eigenvectors of an overlapping Markov chain

Starting with a sequence of i.i.d. [uniform] random variables with m possible values, we consider the overlapping Markov chain formed by sliding a window of size k through the i.i.d. sequence. We study the limiting covariance matrix B_k of this Markov chain and give algorithms for constructing the eigenvectors of B_k. We also discuss the applicability of the results in strengthening Pearsons ² test as well as the relation to approximate entropy and the usefulness in the area of testing the hypothesis of uniformity of random number generators.Mathematics Subject Classification (2000):Primary: 60J10; Secondary: 11K45     

光电经纬仪的跟踪误差及其检测

本文开头指出了跟踪性能是光电经纬仪第一重要技术指标，接着叙述了跟踪原理和跟踪误差的检测方法，并对跟踪误差进行了较深入的分析讨论文章最后，将跟踪误差分门别类，介绍了降低跟踪误差，提高跟踪性能的途径。     

Randomly generated polytopes for testing mathematical programming algorithms

Randomly generated polytopes are used frequently to test and compare algorithms for a variety of mathematical programming problems. These polytopes are constructed by generating linear inequality constraints with coefficients drawn independently from a distribution such as the uniform or the normal. It is noted that this class of ‘random’ polytopes has a special property: the angles between the hyperplanes, though dependent on the specific distribution used, tend to be equal when the dimension of the space increases. Obviously this structure of ‘random’ polytopes may bias test results.     

Two step-down tests for equality of covariance matrices

The classical problem of testing the equality of the covariance matrices from k ? 2 p-dimensional normal populations is reexamined. The likelihood ratio (LR) statistic, also called Bartlett’s statistic, can be decomposed in two ways, corresponding to two distinct component-wise decompositions of the null hypothesis in terms of the covariance matrices or precision matrices, respectively. The factors of the LR statistic that appear in these two decompositions can be interpreted as conditional and unconditional LR statistics for the component-wise null hypotheses, and their mutual independence under the null hypothesis allows the determination of the overall significance level.     

签字笔中油墨成分的检验方法研究进展

介绍了常见签字笔的分类,并综述了近十年中签字笔油墨成分检测方法的研究进展,包括光谱法(拉曼光谱法、红外光谱法、显微分光光度法、紫外-可见导数光谱法),色谱法(薄层色谱法、气相色谱-质谱法、高效液相色谱法、高效毛细管电泳法、裂解气相色谱法)和综合分析法等(引用文献19篇)。     

Active incremental Support Vector Machine for oil and gas pipeline defects prediction system using long range ultrasonic transducers

This work proposes a long range ultrasonic transducers technique in conjunction with an active incremental Support Vector Machine (SVM) classification approach that is used for real-time pipeline defects prediction and condition monitoring. Oil and gas pipeline defects are detected using various techniques. One of the most prevalent techniques is the use of “smart pigs” to travel along the pipeline and detect defects using various types of sensors such as magnetic sensors and eddy-current sensors. A critical short coming of “smart pigs” is the inability to monitor continuously and predict the onset of defects. The emergence of permanently installed long range ultrasonics transducers systems enable continuous monitoring to be achieved. The needs for and the challenges of the proposed technique are presented. The experimental results show that the proposed technique achieves comparable classification accuracy as when batch training is used, while the computational time is decreased, using 56 feature data points acquired from a lab-scale pipeline defect generating experimental rig.     

激光干扰扩束系统光机结构设计

针对常规红外干扰技术存在的能量无法集中、隐蔽性差且无法进行变倍切换等实际问题,提出一种离轴双反射式激光干扰扩束系统的设计方案,并对离轴双反射镜组,转向平面反射镜及支撑固定机构等主要组成部分进行了光机结构设计.为实现扩束比的变倍切换功能,采用新型离轴副镜组件设计;为减小镜面变形,离轴主副镜组均采用微应力设计.分析结果表明,在-20~+60℃温度范围内,主副镜组轴向最大位移小于等于0.01mm,主副镜组的反射镜面形误差小于等于71.9nm;系统一阶固有频率108.3Hz,其支撑结构应力响应远小于材料的屈服极限.实际测试发现,系统可实现1:10.02(19.92,25.02)扩束比,满足设计技术指标要求.分析及试验结果表明,系统光机结构设计合理,完全满足实际应用要求.     

基于USB3.0和FPGA的传动误差检测系统的设计

为提高机床传动误差检测的速度、实时性以及精度,同时为优化硬件电路的结构,并保证采样数据毫无损失地传至上位机系统,提出了一种高速实时检测方案。通过脉冲插补的思想,提出一种传动误差检测的方法。另外在一块高性能FPGA芯片内部搭建数据预处理以及控制模块,利用USB3.0芯片作传输媒介,有效地减少了该系统外围电路复杂程度,降低了开发难度。并对该系统进行模拟仿真试验。试验结果表明：根据设定的误差曲线换算后的数据,通过另一个FPGA发送至该系统,处理后得到的数据不需要经过后期补偿,其误差曲线很好地归零并形成一条闭合曲线,而低速端转速误差曲线也正确反映了仿真实验的情况。实验结果表明该系统实现了高速实时检测,为机床传动误差检测提供了技术上的支持。     

一种飞行器电气系统综合测试平台设计

为解决传统飞行器电气系统综合测试中存在的测试设备种类繁多、测试项目覆盖性差等诸多问题,在某飞行器测试覆盖能力改进项目中,提出一种基于PXI总线架构的综合测试平台设计思路,通过模块化的硬件与软件架构设计,完成飞行器电气系统的综合测试平台设计,并结合实际测试需求进行具体开发,实践表明该系统能够保证飞行器现场测试有序、规范、安全。