机械式温湿度表不确定度评定

由于机械式温湿度表测量误差不可避免,其测量不确定度的评定是计量检定工作的重要内容。为确保测量数据的准确可靠,文章依据JJF 1059.1-2012《测量不确定度评定与表示》的要求,介绍了机械式温湿度表测量结果不确定度评定的一般方法和详细步骤。以精密露点仪、LF-300X温湿度检定箱和自校式铂电阻数字测温仪为标准器,以WS-1型机械式温湿度表为被检表,通过实例具体说明评定方法,并给出具体的扩展不确定度评定值。     

干涉测距仪测量不确定度评估

本文对与干涉测距仪（IDM）测量不确定度有关的参数进行了讨论。采用一个简单、鲁棒装置测量了约12cm距离,扩展不确定性为±16．4,um,发现测量不确定度受波长测量精度制约。该设置可测量距离达56m,它也能够轻松确定测量臂和参考臂之间等光程差的点。LabVIEW程序用于条纹的计数,快速傅立叶变换（FFT）对噪声按频率进行选择性过滤。虽然本文对不确定性的测定不能代表同类测量距离的最高不确定度,但该测量方法提供了可溯源于长度单位为米的测量值。     

基于SR7265硬件的虚拟锁相放大器、频谱仪、阻抗计和半导体参数分析仪

锁相放大器是用来测量微弱信号的专用仪器.即使噪音上千倍于被测信号,通过锁相放大器,也能得到精确结果.随着数字信号处理技术在仪器中的应用,可编程仪器变得越来越灵活.结合虚拟仪器的技术,论文通过对SR7265的硬件重新编程,在同一个硬件上实现了虚拟锁相放大器、虚拟频谱仪、虚拟阻抗计和虚拟半导体参数分析仪等等功能.本虚拟仪器采用了4层的逻辑结构.同样的功能也在一个FPGA板上成功地部署.     

基于可见光和近红外光图像的浊度分析

传统的光电检测系统需要复杂的电路和分光系统,以及需要专业人员进行操作。为了取而代之,结合数码摄像头的成像特点和计算机的高速信息处理能力,提出了一种利用摄像头测量浊度的方法。设计了两种基于可见光和近红外光摄像头的浊度测量装置和一个恒定光强的光源驱动电路。利用自主开发的图像处理软件获取浊度图像中的RGB数据,并将其转换为CIE Lab颜色空间。根据亮度、色差与浊度之间的关系,建立了0-1000 NTU、小于100 NTU、大于100 NTU范围内的可见光和近红外装置的亮度和色差的浊度检测模型。对所提出的模型进行对比分析,选择综合性能最好的两个测量模型进行融合,生成了一个新的测量模型。实验结果表明,三种模型与商用浊度仪的测量结果之间的相关性均大于0.999,融合模型的误差在1.05%以内,均方误差为1.14。可见光装置在低浊度测量时表现出的误差较小,受图像颜色影响较小。近红外装置在全量程和高浊度测量时更稳定、准确,更适合此类测量。     

Multiphase flow measurements using coupled slotted orifice plate and swirl flow meter

Multiphase flow metering is a major focus for oil and gas industries. The performance of a modified version of a close coupled slotted orifice plate and swirl flow meter for multiphase flow was evaluated to provide further development of a new type of multiphase flow meter. The slotted orifice provides well homogenized flow for several pipe diameters downstream of the plate. This characteristic provides a homogeneous mixture at the inlet of the swirl meter for a wide range of gas volume fractions (GVF) and flow rates. In order to evaluate the performance of the designed flow-meter, its response was investigated for varying pressures and water flow rates. The proper correlations were established to provide high accurate two-phase flow measurements. The new proposed approach provides the GVF measurement with less than ±0.63% uncertainty for GVF range from 60% to 95%.     

超声波式数字测距仪的研究

介绍了超声波式数字测距仪的原理，主要论述了在测量中存在超声波的传播速度随着温度的变化和其它干扰信号对测量的影响问题，对这些存在的问题提出了解决的方法。     

浅谈砝码对烘干法水分测定仪装置和测量结果的影响及不确定度评定

水分测定仪是目前实现食品、药品、谷物水分含量快速检测的唯一测量仪器。砝码是其必备的测量设备之一。根据水分测定仪的显示方式和衡量装置的不同,目前市场上的烘干法水分测定仪分为模拟显示水分测定仪和数字显示水分测定仪。本文详细阐述砝码在烘干法水分测定仪运用,进一步阐述烘干法水分测定仪测量结果不确定度评定。     

Digital filtering of acceleration data acquired during the intervention of a lift safety gears

In this paper two digital filters are applied to elaborate acceleration data acquired from two accelerometers fixed in a lift frame during safety gears tests. The experimental tests consist in free falls of a test lift car and the subsequent gripping phases initiated by the safety gears activation due to over-speed condition. Unfortunately, the reliability of acceleration data is heavily impaired by measurement noise, which needs to be suppressed to the largest extent possible in order to use the data for comfort evaluation. To this end, two classes of digital filters are tested: the Savitzky–Golay and the Butterworth filters. This choice is motivated by the key features of these filters, including their computational simplicity and high suitability to represent time varying features in acceleration measurements. A tuning procedure is proposed for these filters, such that the measurement noise corrupting the experimental data is maximally dumped.     

国外CCD检测技术在工业中的应用与发展

CDD图像传感器以其光谱响应宽、动态范围大、灵敏度和几何精度高、噪声低、便于进行数字化处理和与计算机连接等优点,在工业测控中得到广泛应用。该文简要介绍了CCD图像传感器的检测原理和它在工业检测中的应用现状,分析了现有CCD检测技术在应用中存在的问题和局限,指出了CCD传感器在工业检测应用中的发展方向。     

In-process out-of-roundness measurement probe for turned workpieces

A new in-process and non-contact probe is proposed to measure the diameter and the roundness of turned workpieces. The initial probe discussed in previous publications exhibited diameter measurements with good accuracy (uncertainty 5 μm over 100 mm). This paper discusses the implementation of roundness measurement into the initial probe and its performance. The principle of the roundness measurement is based on the relationship between the displacement and the light intensity. The probe delivers a maximum error of 0.5 μm with an uncertainty of 1 μm for roundness measurement over a range of 100 mm diameter.     

Rhodamine WT tracer experiments to check flow measurements in sewers

Flow meters are widely used in urban hydrology to assess discharges, volumes and transport of pollutant loads but may deliver wrong or biased results if they are not checked appropriately. In order to help operators to check flow meters and their discharge values, an operational protocol based on Rhodamine WT tracer experiments is proposed, tested and applied to various case studies. It includes a detailed uncertainty assessment, the reduction of the uncertainty in the injected mass of tracer and a complete data processing. Using Rhodamine WT as a tracer offers the following advantages: (i) low injection volume and mass, allowing tracer experiments even for high flow conditions, (ii) absence of Rhodamine WT in wastewater, which ensures low and stable background signal, (iii) on-line data acquisition at short time step with a portable fluorimeter. Tests show that the protocol provides accurate flow measurements when compared to reference values (electromagnetic flow measurements and salt tracer experiments), with repeated tracer injections giving discharge values with relative standard uncertainties of approximately 5%. Field applications confirm it is an efficient approach to improve the quality of flow measurements in sewers. After an in situ flow meter is checked for various values of discharge, a correction function can be established if necessary for each specific measurement site if there is no alternative solution to improve the measurements by changing the location and position of the sensor or by replacing it by a more appropriate technology. In its present state, the protocol can be applied as a routine method. As a complement, CFD modeling is applied to one of the case studies to explain the causes of bias in flow meter measurements.     

Correction of Dynamic Error Result from Measurement System Limitations

The main cause of dynamic errors is due to frequency response limitation of measurement system.One way of solving this problem is designing an effective inverse tilter.Since the problem is ill-conditioned,a small uncertainty in the measurement will cause large deviation in reconstructed signals.The amplified noise has to be suppressed at the sacrifice of biasing in estimation.The paper presents a kind of designing method of inverse filter in freqtency domain based on stabilized solutions of Fredholm integral equations of the first kind in order to reduce dynamic errors.Compared with previous several work,the method has advantage of generalization.Simulations with different Signal-to-Noise ratio (SNR) are investigated.Flexibility of the method is verified.Application of correcting dynamic error is given.     

A new correlation method for high sensitivity current noise measurements

The properties of a differential transconductance amplifier coupled with a four channel measurement system are exploited in order to reach a very high sensitivity in current noise measurements. In particular, it is demonstrated that, in proper conditions, the noise contributions coming from the active and passive devices that make up the transresistance amplifier can be virtually eliminated. Moreover, the proposed measurement method allows the evaluation of the impedance of the device under test from noise measurement data. Actual measurement results are also reported that demonstrate the effectiveness of the proposed approach.     

Non-contact measurement technique for dimensional metrology using optical comb

This paper proposes a non-contact pulsed interferometer for dimensional metrology using the repetition frequency of an optical frequency comb. A compact absolute-length measuring system is established for practical non-contact measurement based on a single-mode fiber interferometer. The stability and accuracy of the measurements are compared with those from a commercial incremental laser interferometer. The drifts of both systems have the same tendency and a maximum difference is approximately 0.1 μm. Subsequently, preliminary absolute-length measurements up to 1.5 m were measured. The signal-to-noise ratios of the small signals are improved by a frequency-selective amplifier. It is apparent that the noise is rejected, and the intensity of the interference fringes is amplified, achieving a maximum standard deviation of measurement approximately 1 μm. The proposed technique can provide sufficient accuracy for non-contact measurement in applications such as a simple laser-pulse tracking system.     

Diagonal in space of coordinate measuring machine verification using an optical-comb pulsed interferometer with a ball-lens target

This paper presents a new optical method of coordinate measuring machine (CMM) verification. The proposed system based on a single-mode fiber optical-comb pulsed interferometer with a ball lens of refractive index 2 employed as the target. The target can be used for absolute-length measurements in all directions. The laser source is an optical frequency comb, whose repetition rate is stabilized by a rubidium frequency standard. The measurement range is confirmed to be up to 10 m. The diagonals of a CMM are easier to verify by the proposed method than by the conventional artifact test method. The measurement uncertainty of the proposed method is also smaller than that of the conventional method because the proposed measurement system is less affected by air temperature; it achieves an uncertainty of approximately 7 μm for measuring lengths of 10 m. The experimental results show that the measurement accuracy depends on noise in the interference fringe, which arises from airflow fluctuations and mechanical vibrations.     

A novel laser wavelength meter based on the measurement of synthetic wavelength

The accuracy of the current wavelength meter using optical interferometry is limited by the numbers of fringe counted. To solve this problem, a novel laser wavelength meter based on the measurement of synthetic wavelength is proposed. The unknown wavelength is obtained by measuring the value of synthetic wavelength produced by the unknown and reference wavelengths, and half of this value corresponds to 2π variation of the phase difference between the interference signals of the unknown and reference wavelengths. The optical configuration of the wavelength meter is designed and the measurement principle is analyzed theoretically. To verify its feasibility, three helium-neon lasers' wavelengths were determined experimentally, and a relative uncertainty on the unknown wavelength of the order of 10(-8) was realized. Accuracy analysis shows that this wavelength meter has the advantage of high accuracy when the unknown wavelength is around the standard laser wavelength recommended by CIPM.     

In-situ density measurement for plastic injection molding via ultrasonic technology

Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization. Therefore, in-situ density measurement is of great interest and has significant application value. The existing methods, such as pressure−volume−temperature (PVT) method, have the shortages of time-delay and high cost of sensors. This study is the first to propose an in-situ density measurement method using ultrasonic technology. The analyses of the time-domain and frequency-domain signals are combined in the proposed method. The ultrasonic velocity is obtained from the time-domain signals, and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals. Experiments with different process conditions are conducted, including different melt temperature, injection speed, material, and mold structure. Results show that the proposed method has good agreement with the PVT method. The proposed method has the advantages of in-situ measurement, non-destructive, high accuracy, low cost, and is of great application value for the injection molding industry.