动态测量光栅测长仪的位置误差

介绍了一种光栅测量系统动态位置精度评定的方法,以现有的光栅测长仪为研究对象,高精度HP5529A双频激光干涉仪作为校准系统.利用光栅测长仪编码器产生的A-quad-B脉冲信号触发激光干涉仪进行同步动态数据采集,由激光干涉仪软件来获取和显示位置误差数据,并绘制更真实详细的动态误差图.最后对动态误差实验结果进行分析和讨论.     

数控机床电机-斜齿轮齿条耦合进给系统动态特性分析#br#

数控机床进给系统动态误差是影响加工精度的一个重要因素。针对大型镜像铣床斜齿轮齿条进给系统,通过势能法和切片积分法获得时变啮合刚度,同时考虑啮合误差引入的内部激励建立斜齿轮齿条动力学模型。针对矢量控制电机,建立交流同步伺服电机的双闭环控制动力学模型。将电机模型与齿轮齿条动力学串联构成机电耦合系统动力学模型,通过Simulink 仿真和实验研究,分析啮合误差、电机动态特性对于进给系统动态传递误差的影响,明确了齿轮齿条误差是进给系统的主要误差源。研究成果可为高动态精度的进给系统设计提供参考。     

数控机床电机-斜齿轮齿条耦合进给系统动态特性分析#br#

数控机床进给系统动态误差是影响加工精度的一个重要因素。针对大型镜像铣床斜齿轮齿条进给系统,通过势能法和切片积分法获得时变啮合刚度,同时考虑啮合误差引入的内部激励建立斜齿轮齿条动力学模型。针对矢量控制电机,建立交流同步伺服电机的双闭环控制动力学模型。将电机模型与齿轮齿条动力学串联构成机电耦合系统动力学模型,通过Simulink 仿真和实验研究,分析啮合误差、电机动态特性对于进给系统动态传递误差的影响,明确了齿轮齿条误差是进给系统的主要误差源。研究成果可为高动态精度的进给系统设计提供参考。     

光栅莫尔条纹信号正交误差的补偿

为了补偿在作用微处理器对光栅莫尔条纹信号进行相位细分时，由于两路莫尔条纹信号不正交所引起的误差，推导了正交误差方程并给出了求解方法和相应软件。实验证明，引入相应补偿程序之后，细粉数明显提高。     

粗光栅位移测量系统细分误差的来源与消除分析

本文从粗线纹光栅位移测量系统的原理出发，对里周期性变化的细分误差作了详细的理论分析，并得到了实验的验证．同时提出了从硬件上和软件上消除细分误差的方法，为进一步研制高精度数显系统打下基础。     

求解厚壁筒动态应力强度因子的累进积分法

将累进积分法引入动态应力强度因子的求解过程中，并分别用该方法和有限元法求 了厚壁筒的动态应力强度因子比较两者的结果，可见累进积分法具有公式简单，编程易于实现等优点，可极大地方便于工程应用。     

直流电路系统测试圆光栅的分析与应用

分析了采用直流电路系统测试圆光栅直径误差 Φi(或刻线误差 θi)时所产生的差异等问题 ,讲述了能较真实准确地得出圆光栅 Φi(或 θi)这一单项误差指标的测试与数据处理方法。此方法已在实验与实际检测结果中得到了充分验证     

双光栅准直测量系统及其精度分析

本文基于双光栅法测量准直性原理，在550mm的平行光管上完成了一系列的实验研究，相对测量精度达到0．036％，并对误差源及提高测量精度的方法作了一定的分析。     

圆光栅检测仪的研制

介绍了一种高精度、精密、自动化、动态测量的光栅检测仪,测量光栅盘的扩展不确定度为０．０８”。该仪器采用了高回转精度的空气静压轴承及多头均化技术,减小了参考盘刻划误差的影响,同时,采用了计算机系统控制测量过程,进行数据处理,实现了自动化测量,检测结果和误差曲线由打印机打印输出。     

双光栅准直测量系统及其精度分析

本文基于双光栅法测量准直性原理，在５５０ｍｍ的平行光管上完成了一系列的实验研究，相对测量精度达到０．０３６％，并对误差源及提高测量精度的方法作了一定的分析。     

Multi classifier-based score level fusion of multi-modal biometric recognition and its application to remote biometrics authentication

Biometric recognition has become a common and reliable way to authenticate the identity of a person. Multimodal biometrics has become an interest of areas for researches in the recent past as it provides more reliability and accuracy. In multimodal biometric recognition, score level fusion has been a very promising approach to improve the overall system's accuracy. In this paper, score level fusion is carried out using three categories of classifiers like, rule classifier (fuzzy classifier), lazy classifier (Naïve Bayes) and learning classifiers (ABC-NN). These three classifiers have their own advantages and disadvantages so the hybridization of classifiers leads to provide overall improvements. The proposed technique consists of three modules, namely processing module, classifier module and combination module. Finally, the proposed fusion method is applied to remote biometric authentication. The implementation is carried out using MATLAB and the evaluation metrics employed are False Acceptance Rate (FAR), False Rejection Rate (FRR) and accuracy. The proposed technique is also compared with other techniques and by employing various combinations of modalities. From the results, we can observe that the proposed technique has achieved better accuracy value and Receiver Operating Characteristic (ROC) curves when compared to other techniques. The proposed technique reached maximum accuracy of having 95% and shows the effectiveness of the proposed technique.     

基于间歇励磁和信号重构的电磁水表变送器研制

针对电磁水表低功耗的要求,提出间歇励磁方式,每周期进行一次三值波励磁;针对电磁水表需要在励磁电流小、传感器输出信号非常微弱的条件下实现极低测量下限的要求,提出信号重构滤波的处理方法,将幅值解调后的信号重构为矩形波信号,以便对信号进行梳状带通滤波,从而保证电磁水表的测量准确度.研制了基于MSP430低功耗单片机的变送器,...     

光纤准白光干涉信号数字化处理方法

提出一种光纤准白光干涉信号数字化处理方法。该方法采用干涉条纹脉冲实现干涉包络信 号同步采集,克服了导轨移动速度不均匀造成的影响;通过高斯函数曲线拟合方法高精度确定干涉信号零光程差点;大大提高了准白光干涉信号定位精度。为消除包络信号采样边界点不确定性带来的误差,采用外插法进行补偿。实验表明,采用该方法对光纤准白光干涉信号零光程差位置的定位精度优于0.5个干涉条纹。     

50th Anniversary Article: Comparison Studies of Full Wavefield Signal Processing for Crack Detection

The signals acquired by measurements of elastic wave propagation have been used for damage detection since the 1970s. The measurements have been carried out mostly by using piezoelectric transducers of various types. Many different sensor configurations and data processing have been proposed to detect and localise structural defects, both for real‐time and off‐line testing. Nevertheless, in the last decade, significant progress in the measurement techniques such as scanning laser Doppler vibrometry and shearographic interferometry has been made. These techniques enable measurement of a full wavefield of elastic waves. This opens up new possibilities and solutions for the problems of the damage detection in structures. Many researchers successfully applied this type of measurements for the damage detection and localisation in thin‐walled structures. Moreover, advanced signal processing techniques, such as wavenumber filtering, give the possibility of damage size estimation, by filling the gap between damage detection and damage prognosis. The aim of this paper is to give a comprehensive review of methods used for the full wavefield measurement. It also describes and compares selected signal processing algorithms developed for damage detection and visualisation based on these measuring techniques. Criticism aspects, as well as advantages of each algorithm, are denoted based on the authors' expertise in the field.     

基于小波包变换的内燃机气阀漏气诊断方法

探讨了利用缸盖振动信号诊断内燃机气阀漏气的一种新方法－－小波包方法。诊断机理分析和实验研究表明,缸盖 振动信号中关于气阀漏气的特征信息集中在高频段,故选用了小波包变换作为信号处理的基本方法,因为小波包变换较之小波变换在中高频段具有更高更均匀的频率分辨率;对实测信号的分析和处理结果表明了小波包在该领域的适用性;建立了基于马氏距离法的气阀漏气多指标诊断模型;进行了实机诊断,取得了预期的效果。     

A digital signal-processing instrument for impedance measurement

A digital signal processing (DSP)-based instrument for impedance measurement is proposed. It implements two measurement techniques: the first technique allows the tracking of a time varying impedance to be carried out, and the second assures that good accuracy is obtained in reasonable measurement times. Both the software and the hardware of a prototype model are described in detail. The measurement rates and accuracy are evaluated and compared with those obtained using a reference Digibridge for a wide range of impedance values     

Genetic programming-based perceptual shaping of a digital watermark in the wavelet domain using Morton scanning

Digital watermarking is gaining a lot of acceptance as a solution to the problem of copyright protection and authentication of multimedia data while working in a networked environment. In this article, an adaptive discrete wavelet transform-based watermarking technique is proposed. The technique exploits perceptual masking properties to embed the watermark in an invisible manner. Genetic programming (GP) is used to make a tradeoff between the two conflicting properties, namely robustness and imperceptibility by choosing an optimum watermarking level for each coefficient of the cover image. Extensive experiments have been carried out, which show that our proposed technique is more resistant against common signal processing operations and geometric attacks than some well-known existing techniques while it preserves the quality of the original image.     

面向批料流测量的科氏质量流量计正交解调方法实现

为了提高科氏质量流量计在批料流工况下的测量精度,根据正交解调算法具有快速响应的特点,选取该算法作为批料流下的信号处理方法,并解决实现过程中的技术难点。利用正弦信号周期性的特点,实现解调信号单周期有限点数据循环调用;采用FIR陷波器和IIR低通滤波器级联完成对解调后信号的滤波,在保证滤波效果的同时降低了算法运算量;为了去除计算结果中的奇异点同时减小稳态波动,在相位差后期处理中加入两级平均;优化了算法实现过程中的资源分配。在此基础上,研制了科氏质量流量变送器,并进行了单相流和批料流标定实验,其测量误差小于0.1%,重复性小于0.05%。实验结果表明,正交解调算法在批料流下具有较好的测量精度,同时所研制的变送器具有较好的性能。     

Reliability of signal processing technique for pavement damages detection and classification using ground penetrating radar

Ground penetrating radar (GPR) signal processing is a nondestructive technique, currently performed by many agencies involved in road management and particularly promising for soil characteristics interpretation. The focus of this paper is to assess the reliability of an optimal signal processing algorithm for pavement inspection. Preliminary detection and subsequent classification of pavement damages, based on an automatic GPR analysis, have been performed and experimentally validated. A threshold analysis of the error is carried out to detect possible damages and check if they can be predicted, while a second threshold analysis determines the nature of the damage. An optimum detection procedure is performed. It implements the classical Neyman-Pearson radar test. All the settings needed by the procedure have been estimated from training sets of experimental measures. The overall performance has been evaluated by looking at the usual receiver's operating characteristic. The results show that a reasonable performance has been achieved by exploiting the spatial correlation properties of the received signal, obtained from an appropriate analysis of GPR images. The proposed system shows that automatic evaluation of subgrade soil characteristics by GPR-based signal analysis and processing can be considered reliable in a number of experimental cases.     

计量光栅信号质量综合评价系统

光电轴角编码器中的莫尔条纹信号质量决定了整个系统的细分精度。计量光栅信号质量综合评价系统由编码器、数据采集卡和相应的软件组成，采用一种以莫尔信号离散采集和数据处理为主的数字化检测方法，实现了莫尔条纹信号质量各项指标的评价，对提高测量精度以及光栅系统的设计具有一定意义。