Development and validation of a dynamic primary standard for unsteady liquid flow calibration

LNE-CETIAT liquid flow laboratory is the French Designated Institute for liquid water flow rate from 1 g h⁻¹ to 50 t h⁻¹. Historically, its primary standards are based on the flying start and stop gravimetric method. The best relative expanded uncertainty for liquid mass flow rate is 0.05% (k = 2). In the scope of the Joint Research Project Metrowamet and its mission to maintain and develop the French standards for liquid flow, LNE-CETIAT has developed and validated a dynamic primary standard for unsteady liquid flow calibration. This paper will first present the developped system, which is composed of a dynamic flow generator and a dedicated measuring system together with its own software for data acquisition and processing. The validation, realized by intra and inter-laboratory comparisons for static and dynamic flows, is presented in the third chapter. Finally, the validation of the measurement and calibration capabilities, based on internal tests and inter-laboratory comparisons are presented.     

浅议电子衡器的非线性校正

采用非线性校正,可以改善衡器的计量误差。本文主要介绍使用二次曲线拟合法进行非线性校正的数学模型。     

A new approach to gas flow calibration

Primary gas flow standards create calculable flow rates using two different techniques. Displacement systems rely upon the accurate determination of the first order change in position of an object being displaced by gas flowing at a constant pressure. Pressure, volume, temperature and time (PVTt) systems provide a nearly constant mass flow of gas to an accumulation tank of known volume over a fixed time interval. Measurements of pressure, temperature and time are used to calculate flow rate.     

A prototype portable system for EEG measurements

In this study, a prototype EEG recording and analysis module for biomedical research applications is designed. The design of the system consists of an analog and a digital part. The system has two signal channels, but it can be extended to six channels construction. The analog module involves the following units; an input instrumentation amplifier, gain adjustable amplifier, band-pass filter, and a driven-right-leg- (DRL) circuit. The digital board consists of A/D converter and RS232 communication unit. In order to test system, the circuit simulation and the real-time EEG measurements are implemented. The proposed EEG system can be used in our department’s biomedical laboratory.     

Development of remote calibration system for pressure standard

A remote calibration technology for disseminating pressure standard has been developed. In the remote calibration, a transfer standard is transported from a calibration laboratory to a client’s site where a calibration item is used. Using the transfer standard and the internet, the calibration item is calibrated on site. For the remote calibration, integrated transfer standards were newly developed in different pressure ranges. Each transfer standard includes a pressure controller, two or three precise pressure transducers, environmental measurement devices and an inclinometer in one box. Also the calibration protocol was examined to perform the remote calibration efficiently using the transfer standard. In order to prove the effectiveness of the remote calibration, the demonstration experiments were performed domestically and internationally. Here, the calibration protocol for the remote calibration and the functional overview of the newly developed transfer standards are described. The experimental results are also shown.     

便携式舰船热工仪表校准装置设计

根据舰船热工参数仪表计量需求。研究设计了便携式计量校准装置。装置利用ARM嵌入式计算机系统作为中心控制器,完成了压力、温度信号的输出与测试,提高了校准装置的整体性能及便携性,为舰船仪表校准与测试工作的开展提供了技术支持。     

The set up of primary calibration system for shock acceleration in NML

This paper mainly describes Taiwan’s metrology National Measurement Laboratory (NML) to set up and evaluate a shock accelerometer calibration system which follows the ISO 16063-13:2001 standard. The environmental shock testing of electro-acoustics or electronic spare parts, the product packing falling impact, the automobile collision and the helmet impact test and so on are more and more important for quality and safety. In consideration of that, NML has started to establish the primary shock calibration system which calibrates the accelerometer sensitivity and trace to the metric unit since 2009. The shock machine structure comprises three parts; they are the electromagnetic high-speed hammer, airborne hammer and airborne anvil. The shock machine impact source of primary shock calibration system is excited by electromagnetic method.     

A relative calibration method for a valve leakage rate measurement system

This paper presents a relative calibration method for an internal valve leakage rate measurement system using both microcontroller and acoustic emission (AE) methods. An air jet was selected to calibrate because it provides a frequency spectrum similar to the AE spectrum obtained from the valve leak, especially in the frequency range of 100-300 kHz. Three AE sensors mounted on a valve were used to validate the system calibration. Ratios between the average energy (AErms) were obtained from each pair of sensors, and these ratios were used to transfer the leakage AErms value. Subsequence, its performance to predict the leakage rate in the laboratory and in the field was tested. The error is less than 5% in almost cases. Its benefit is to reduce the recalibration time when a part of measurement system is changed. Accordingly, inexpensive equipment including an AE sensor was built, and its system performance was revealed.     

二维旋转平台下的相机参数标定

针对可旋转相机的参数标定问题,提出了一种基于二维旋转平台的相机成像模型。首先,通过一对坐标系的变换与逆变换,将相机的旋转平移变换关系转换为二维旋转平台纯旋转关系;然后,借助旋转平台读数以及相机到旋转平台的固定变换关系,实现相机内参的精确标定以及任意位置间相机外参的相互转换;最后,利用标定出的相机与旋转平台间变换矩阵实现不同位置相机参数的转换。相比于传统固定相机的标定方法,本文提出的方法标定获得的相机内参具有更好的收敛性,而且能够标定出相机到旋转平台的变换矩阵,从而实现相机坐标系变换参数的精确计算。实验结果表明,在标定模板图像数量相同时,与常用的张氏标定法相比,本文提出的方法标定获得的相机内参具有更快的收敛速度。棋盘格角点重投影坐标与实际拍摄图像中棋盘格角点坐标相对比,平均误差约为0.12pixel,表明该方法具有较高精度。     

Stylus-laser surface calibration system

A stylus-laser surface calibration system was developed to calibrate the NIST sinusoidal roughness Standard Reference Materials (SRM) 2071-2075. Step height standards are used to calibrate the stylus instrument in the vertical direction, and a laser interferometer is mounted on the traversing unit of the stylus instrument to calibrate the instrument in the horizontal direction. The calibration uncertainty (±2δ) for SRM 2075 is ±1.2% for roughness calibrations ((R_a = 1 μm), and ±0.06% for spatial wavelength calibrations (S_m = 800 μm).     

基于特征吸收波长板的色散型高光谱传感器光谱定标技术

高光谱传感器的光谱定标是实现高光谱遥感定量化的关键。为了克服传统的基于单色仪扫描的光谱定标方法存在的设备昂贵、耗时等缺点,实现色散型高光谱传感器在野外或飞行中的实时、高精度定标,提出了一种基于特征吸收波长板的色散型高光谱传感器系统级光谱定标方法。分别对特征吸收波长板和漫反射参照体反射信号进行了比对测量,通过优化计算得到了传感器通道的中心波长和带宽。该方法消除了待定标传感器的光谱响应和光源的光谱能量分布带来的影响,能快速准确地实现色散型高光谱传感器的波长定位。运用该技术实现了对野外光谱辐射计FieldSpec(UV/VNIR的光谱定标,并对影响光谱定标精确度的因素进行了分析计算,结果表明,该方法实现的波长准确度0.5 nm,可满足色散型高光谱传感器实时、高精度光谱定标的需要。     

Approximate solution of limit angular speed for externally loaded rotating solid disk

The present work proposes a numerical method to investigate the stress and deformation states of rotating disks using variational method taking the radial displacement field as unknown variable. Assuming a series approximation following Galerkin's principle, the solution of the governing partial differential equation is obtained. The analysis is carried out for various disk geometries and the effect of geometry and loading parameters on the stress and deformation states is investigated. Limit angular speed of the disks is also calculated for various system parameters and reported in dimensionless form. The results are validated with those of other researchers for appropriate values of the system parameters and very good agreement is observed. It is observed that the present methodology is quite robust, stable and realistic and the documented tables and curves may be used by the practicing engineers as design monograms.     

一种结合 TCP 标定的深度相机手眼标定方法

手眼标定是机器人实现视觉引导下精准作业中的关键技术。传统手眼标定和机器人工具中心点(TCP)标定分开进行,存在较大累积误差,同时针对深度相机的手眼标定存在精度不足的缺点。本文提出了一种结合TCP标定过程同步标定深度相机手眼关系的新方法。方法基于深度相机观测和TCP标定相同的标定平面,相机坐标系下标定平面方程和机械臂坐标系下标定平面方程为对应关系,通过平面方程之间的变换来计算手眼关系。本文方法减少了TCP和手眼关系独立标定累积误差影响,节约标定时间和标定件成本。仿真和实测结果表明,本文方法提高了深度相机手眼标定精度,标定后实测位置误差平均为0.2 mm,为机器人视觉控制系统高精度作业所需标定提供了一种新的思路。     

自动气象站风速传感器自动化检定系统研发

自动气象站风速传感器自动化检定系统由广东省大气探测技术中心自主开发研制,用于全自动检定国内现用自动气象站所配套的各型风速传感器,并兼容对常规风速仪器的自动化检定／校准。本文从其工作原理、技术架构、系统组成及程序模块组成等对该系统做了简单的介绍。     

基于C8051F020单片机的底盘测功机速度标定仪设计

底盘测功机可实现在不同工况、不同负载下动力性能的连续测量,从而评定汽车的综合性能。而对底盘测功机的的检定仪器目前国内尚少。本文分析了对底盘测功机的检测原理。设计了一种基于C8051F020单片机的底盘测功机速度标定仪。该仪器已经在实质检测线上进行多次测试,达到了较为理想的检测效果,完全符合国家的测功装置的检定规程标准。     

紫外ICCD辐射定标的研究

国内至今尚未见有紫外增强型CCD(UV-ICCD)探测器定标的相关研究报道,为保证紫外测量数值结果的准确性和电力电晕探测等应用提供直接的技术支持,有必要对UV-ICCD的辐射定标技术进行研究,以建立输入辐照度和探测器数字化输出之间的响应特性。推导了辐射定标的原理,并对UV-ICCD探测器进行了基于标准氘灯的辐射定标,标准光源由美国国家标准和技术研究所(NIST)标定,其不确定度为5％。实验标定了在固定积分时间和MCP增益情况下UV-ICCD探测器的响应以及UV-ICCD探测器响应与MCP增益之间的关系。初步的定标数据显示,UV-ICCD探测器的响应是线性的,MCP增益与输出的图像平均灰度值成正比。最后,对影响定标结果的不确定度进行分析,分析结果表明辐射定标的最大误差约为7.94％,满足精度要求。     

Risø calibration quartz – A challenge for β-source calibration. An applied study with relevance for luminescence dating

Risø calibration quartz (RCQ) is used worldwide in luminescence laboratories to calibrate β-sources. RCQ is advantageous because the inherent γ-dose is determined conveniently with a blue light stimulated luminescence (BLSL) single aliquot regeneration (SAR) protocol and dose equivalents (D_Es) are highly reproducible with standard errors of the mean of usually <2%. We report on a series of tests on the recoverability of known β-doses from RCQ and on D_E-determination of γ-dosed RCQ with varying SAR-measurement parameters. Evaluated alone, these raise doubt whether the precise calibration results are systematically correct. However, it is likely that cutheat and preheat adjustment of ‘quick calibration’ as applied by staff members of the Radiation Research Division of the Technical University of Denmark when installing a new luminescence reader in a customer’s laboratory are appropriate to minimize systematic errors. This finding is suggested by comparative calibration of a β-source with RCQ and another γ-irradiated quartz.     

机器人视觉系统标定问题研究综述

在视觉反馈机器人的控制中,摄像机的标定是一个基本的、重要性的问题.该文首先对摄像机的成像模型进行分析,明确了视觉系统标定的主要任务,然后从离线标定和在线标定两方面阐述了相关的研究思路和方法,为机器人视觉系统的研究提供了参考.     

Development of low-pressure calibration system using a pressure balance

A new calibration system for low-pressure is now under development at NMIJ/AIST. The new system is designed to calibrate pressure transducers in the pressure range of less than 10 kPa in absolute mode. The pressure generation technique needs only a single pressure balance and the pressure in the bell-jar is used as a calibration pressure instead of the system pressure. In this paper, the outline of the calibration system and the measurement results are described.     

Optimal calibration for rotating analyzer ellipsometer

We have modeled most errors, which affect the measurement accuracy, with Jone’s matrix. From the simulation, we can characterize the errors and take good aids for selecting components and designing ellipsometer. The traditional residual method has good performance when there are only azimuth angle errors and extinction errors, but it has not good performance when there are other errors. We have proposed the optimal calibration method for overcoming the residual method. The optimal method selects error values to have the least square difference between the measured thickness and the simulated thickness. We can reduce the design variables to three, incident angle error, and azimuth angle errors of polarizer and analyzer. The optimization results are slightly different from the residual method, and have smaller standard deviation of errors than the residual method. The experiment shows good agreement with the simulations.