Effect of Automation on GRR in Tactile Measurement

Gage Repeatability and Reproducibility (GRR) is an inevitable exercise in any precision production environment. The importance of GRR increases manifold when we are carrying out some result oriented quality improvement exercise like a Six Sigma project, where under measure stage we need to validate our measurement system for performance characteristic. Tactile measurement technique is one of the most commonly used measurement technique in industry to ascertain the quality of a manufactured product. The present work is a comparative study to calculate GRR of tactile measurement process, in two different ways, on a co-ordinate measurement machine (CMM). In the present study, GRR has been calculated with four appraisers and four parts and the measurement data has been obtained by operating CMM in manual mode as well as automatic (programmable) mode. Experimental results conclude that GRR improves in a very significant way when measurements are done in automatic mode. This study is especially relevant in R&D environment as in R&D many a times measurement has to be carried out on one or two components only where we avoid writing a program of measurement on CMM and measurement is mostly carried out in manual mode.     

Measurement Uncertainty of Dew-Point Temperature in a Two-Pressure Humidity Generator

This article describes the measurement uncertainty evaluation of the dew-point temperature when using a two-pressure humidity generator as a reference standard. The estimation of the dew-point temperature involves the solution of a non-linear equation for which iterative solution techniques, such as the Newton?CRaphson method, are required. Previous studies have already been carried out using the GUM method and the Monte Carlo method but have not discussed the impact of the approximate numerical method used to provide the temperature estimation. One of the aims of this article is to take this approximation into account. Following the guidelines presented in the GUM Supplement 1, two alternative approaches can be developed: the forward measurement uncertainty propagation by the Monte Carlo method when using the Newton?CRaphson numerical procedure; and the inverse measurement uncertainty propagation by Bayesian inference, based on prior available information regarding the usual dispersion of values obtained by the calibration process. The measurement uncertainties obtained using these two methods can be compared with previous results. Other relevant issues concerning this research are the broad application to measurements that require hygrometric conditions obtained from two-pressure humidity generators and, also, the ability to provide a solution that can be applied to similar iterative models. The research also studied the factors influencing both the use of the Monte Carlo method (such as the seed value and the convergence parameter) and the inverse uncertainty propagation using Bayesian inference (such as the pre-assigned tolerance, prior estimate, and standard deviation) in terms of their accuracy and adequacy.     

周期测量误差对周期信号时域平均处理结果的影响

时域平均处理是从混有噪声的复杂周期信号中提取简谐分量的有效方法之一。本文从时域平均处理的基本原理出发,探讨了时域平均处理中周期测量误差对简谐分量幅值和相位的影响,并给出了时域平均处理后信号各阶简谐分量幅值衰减量和相位变化与周期测量误差、平均次数以及分量阶次之间的关系式。该关系式较复杂不便于工程应用,本文进一步用简单函数线性组合逼近的方法,得出了简化关系式。仿真和工程实例表明,该简化关系式适合工程应用     

Measurement of duty cycles of photoresist grating masks made on top of multilayer dielectric stacks

We present a novel and nondestructive method for measuring the duty cycles (ratio of ridge width to period) of submicrometer rectangular photoresist gratings made on top of multilayer dielectric stacks. The method exploits the fact that the effective index of the leaky mode that has a strong evanescent tail in the cladding changes with the duty cycle of the grating situated at the interface between the top dielectric layer and the cladding. By comparing measured coupling angles of the leaky mode with a theoretical or experimentally calibrated relationship between coupling angles and duty cycle, one can determine the duty cycle of the grating. This method is applicable even when the grating period is less than the measurement wavelength. It is simple because it does not require any power measurement. Most importantly, it is virtually independent of groove depth. The physical principle of the method and the results of experimental verification are presented.     

Measurement of Nonlinear Phase Distortion in Microwave Limiters under Dynamic Conditions

Nonlinear phase distortion (amplitude-modulation to phase-modulation conversion) in microwave limiters can be different under static and dynamic conditions. A technique for measurement of dynamic phase distortion is described in which a two-tone test signal is used to simulate amplitude modulation with modulating frequencies of the order of megahertz. The two-tone test signal is generated by linearly summing two equal-amplitude sine waves. The result is a constant-frequency amplitude-modulated signal whose envelope varies as a rectified cosine wave at the beat frequency of the two sine waves. There is no phase deviation except at the envelope zeros, where the phase jumps 180°. Measurements are made by splitting the output signal from the limiter into two identical signals and delaying one relative to the other by approximately an odd multiple of one-half the envelope period. The two signals, when displayed on an X-Y cathode-ray tube, produce a pair of filled-in ellipses with major axes at 45° and and 135°. Peak phase deviation is obtained by direct measurement of either ellipse. Measurement data in E band are given for two tunnel-diode amplifier-limiters, a balanced mixer-limiter, and a traveling-wave-tube amplifier followed by a balanced mixer-limiter.     

A Universal Method of Determining the Period of a Multifrequency Signal,Represented in Digital Form

A universal method of determining the period of a complex multifrequency signal and a method of generating a signal with a specified period are described. The use of the method to determine the period of a wattmeter diagram when monitoring and diagnosing rod pump equipment is considered.     

Measurement of ammonia in human breath with a liquid-film conductivity sensor

Measurement of breath NH3 is of interest in clinical applications as it can be used as a measure of kidney/liver functions as well as halitosis. We have developed a liquid-film conductivity sensor to measure NH3 in human breath. A film of dilute H2SO4 is formed on the top of two metal capillary tubes placed in a concentric annular arrangement. The tube exterior has been specially treated to render it hydrophilic. As breath passes over the sensor tip, the film collects NH3 and the solution conductivity (measured by the concentric capillaries functioning as electrodes) decreases accordingly. This initial rate of conductivity decrease was determined to be the best metric (most rapid and least dependent on breath pCO2) for ammonia, relative to time to attain complete neutralization (conductivity minimum) or the final rate of conductivity increase as more ammonia dissolves after neutralization. The absorbing solution composition was optimized so that CO2 does not interfere. Both dynamic measurement using mask sampling and offline balloon sampling were performed. Ammonia readily absorbs on surfaces when significant concentrations of water vapor are present. As such, memory effects are common when analyzing human breath for ammonia. This problem was successfully eliminated. The results from this sensor agreed well with data obtained by a solution-phase fluorometric technique using a porous membrane diffusion scrubber and o-phthalaldehyde derivatization chemistry. For breath CO2 measurement, the applicability of a similar sensor that relies on a NaOH film was also demonstrated.     

激光跟踪仪测量曲面的测量不确定度研究

针对激光跟踪仪用于曲面轮廓度测量的不确定度评定问题,在论述了激光跟踪仪的标定和面向任务的测量不确定度的基础上,重点研究了Monte-Carlo模拟方法评价面向任务的不确定度的基本思想,并提出了虚拟激光跟踪仪的概念.最后通过实验研究,验证了采用Monte-Carlo模拟方法评价激光跟踪仪测量曲面轮廓度的不确定度是可行的.     

2m比长仪纳米级精度线间距测量系统的研究

介绍了2 m比长仪系统的组成,对其采用光电显微镜动态瞄准刻线和激光干涉测长原理进行了分析,研究了提高刻线瞄准精度和激光干涉测长精度的方法及利用现代电子技术实现刻线信号和干涉信号自动同步快速处理方法。自动信号处理系统基于FPGA现场可编程电路技术和计算机技术。通过对金属线纹尺测量的实验表明,依据JJG 331—1994激光干涉比长仪检定规程进行实验,2 m比长仪单次最佳刻线瞄准精度优于10 nm(1σ),对其测量的不确定度分析表明,对于测量高质量的高等别线纹尺,其测量不确定度U=（20+40 L）nm（k=2）。     

压力式气浮测力传感器静特性研究

为了避免多维力测量过程中的耦合现象,提出了一种气浮测力的方法。研究建立了压力式气浮测力传感器的特性方程,研制了一种压力式气浮测力传感器静特性实验装置,对理论研究的结果进行了实验验证。实验结果表明,气腔内气体绝对压力Pd在0.5~3.5kg/cm²范围时,气浮测力传感器的线性度为0.8%,回程误差为0.02%,重复性误差为0.1%。     

Application of Time-Domain Reflectometry for Measurement of Moisture Profiles in a Drying Experiment

The time-domain reflectometry (TDR) method is used for the measurement of moisture profiles in calcium silicate during a drying experiment. The specimens are saturated at first by water, and their lateral sides and one of the face sides are water- and vapor-proof insulated to ensure one-dimensional (1-D) water transport. Then, the drying process is started in an environment with a relative humidity of 20%. Moisture profiles are measured at specified time intervals using the TDR method. The experiment is stopped when the moisture content along the whole length of the sample is lower than the maximum hygroscopic moisture content. The obtained results can be used for the determination of moisture diffusivity in the drying phase of moisture transport.     

多边法位姿测量系统中跟踪方式对测量精度的影响研究

为了精确测量大尺寸位姿,建立了一种由7台激光跟踪干涉仪组成的大尺寸位姿测量装置。根据测量各反射镜的激光跟踪干涉仪数量的不同,采用322和331两种跟踪方式对位姿测量精度的影响进行仿真实验,从而发现被测点位置与基站构成平面的距离相关,由坐标解算公式推导被测点坐标值与测量基站之间的相对位置与测量误差间的误差模型,通过分析x、y、z 方向上误差对距离变化的敏感程度,发现z方向距离变化引起的误差最为敏感。当被测点与测量基站的距离由1300.8mm减小到0mm时,测量误差由2.2μm增大到2626.1μm。实际姿态测量结果表明:当采用一种跟踪方式时可以避免被测点与测站点平面过近,有利于提高系统测量精度,所提出的误差模型可为多边法位姿测量系统的优化布局提供一种量化的理论分析方法。     

一种基于残周期正弦波拟合的相位差测量方法

针对不足一个波形周期的相位差测量,提出使用残周期正弦波拟合算法实现的技术方法,给出了原理和实现过程。针对该条件下相位差的测量不确定度,给出了使用波形局域失真和噪声信号比方式,以实际估计参数条件下的仿真计算进行评估的模式。最后,使用激光测振仪校准中的三个相位之间的相位差进行了实验验证,结果表明,在约0.5个周期条件下获得的相位差与多周期条件下的相位差仅仅相差1°左右,证明了该方法的有效性和可行性,为正弦相位差测量提供了一种新的实现方式。     

坐标测量机面向任务的测量不确定度评定

基于产品几何技术规范,分析了坐标测量机面向任务的测量不确定度主要来源;重点讨论了量值特性指标测量复现性的定义与特点,并针对坐标测量机的测量任务,提出引起坐标测量复现性的主要因素,研究了进行复现性指标评价的实验方案,建立了复现性评定的数学模型;通过孔径测量实例分析,介绍了坐标测量机面向任务的测量不确定度评定方法。结果表明,孔径测量结果的合成标准不确定度为3.2 μm,其中测量复现性的不确定度分量高达2.5μm,在测量结果不确定度中所占比重最大。     

轻型车颗粒物质量排放测量影响因素分析

本文通过对称重环境、滤纸预处理时间、背景颗粒物质量和空气浮力等因素进行对比试验，分析这些因素的变化对颗粒物质量测量结果的影响。结果表明：相对湿度越靠近45%，颗粒物质量测量的偏差越小，结果越稳定；在6～10小时的预处理时间段对滤纸进行称量，既能节约时间成本，又能保证测量精度；适当增加日常背景颗粒物测量频率，并绘制当日背景颗粒物质量变化图，能及时修正背景颗粒物影响；空气浮力对颗粒物质量的影响主要是由大气压力的波动造成的，应及时对试验前后滤纸质量进行浮力修正。     

Precise Measurement of Thermal-Induced Refractive-Index Change in BaTiO(3) on the Basis of Anisotropic Self-Diffraction

We propose a method for precise measurement of the temperature-dependent refractive-index change in BaTiO(3) by use of anisotropic self-diffraction (ASD). In this method the refractive-index change corresponds to the angle deviation of the diffraction pattern. Because only the geometry of the ASD is used for measuring, the precision of measurement is independent of crystal thickness and environmental perturbation. The accuracy of the refractive-index change achieved is 10(-4) when the resolution of the measurement of the angle is ~0.04 degrees . Both the theory and the experiment are demonstrated.     

一种新的复介电常数自由空间测量技术研究

提出了一种新的复介电常数的自由空间测量方法,该方法将介质周期结构引入到复介电常数的测量中。运用多模网络理论与严格的模匹配技术,系统分析了加损耗样品层的介质周期结构的散射特性,详细研究了样品复介电常数对反射峰幅度和中心频率的影响。该测量方法不仅克服了传统自由空间法的不稳定性和相位模糊性问题,而且具有谐振法可以对低损耗介质精确测量且测量过程简单的优点,为复介电常数的精确测量提供了一种新的测量方法和重要的理论指导。     

Rocket Vehicle Surface Reflectance Measurement during Retro-Rocket Firing

This paper describes an experiment and presents data on the reflectance variation of a painted surface during the period when a solid propellant rocket is being fired on the surface. The measurement was made with a helium-neon laser, and the data can be used for heat-transfer calculations.     

基于模糊可能性测量理论零件的合格测量

在考虑零件样本不足的情况下,根据可能性理论,将零件尺寸视为模糊变量,给出了表征它的模糊约束和模糊可能性分布函数。基于模糊可能性测量理论,分析了当零件的尺寸公差带为清晰区间（普通集）和模糊允许区间（模糊集）时,测量零件合格与不合格的模糊可能性测量方法。提出了测量零件合格模糊可能性测量、零件可修复不合格模糊可能性测量和和零件不可修复不合格模糊可能性测量的计算公式,并给出了零件合格模糊可能性测量的变化规律。最后进行了实例计算。     

无转速同步叶尖定时预处理方法及误差分析

提出了一种无转速同步叶尖定时信号预处理方法,通过同一叶片到达不同叶尖定时传感器的振动位移差进行振动参数辨识和转速测量。误差分析表明,该方法可以降低转速测量误差以及转速误差对振动位移测量的影响。分析了振动位移差的测量误差,并与采用转速同步的方法进行了比较。实验结果表明,该方法能够有效地实现叶尖定时测量并具有良好的测量精度。