如何实施计量标准的重复性试验问题的探讨

计量标准的重复性是计量标准考核的重要计量特性,本文主要讨论如何选择被测对象和重复性试验条件,合理地进行计量标准的重复性试验。     

A Principle for Capacitance Measurement, Suitable for Linear Evaluation of Capacitance Transducers

A principle for measurement of capacitance is shown, together with a practical realization. The inherent linearity of output voltage as function of capacitance makes the principle advantageous for the evaluation of capacitance transducers.     

Measurement of the S-Parameters of 2n-Terminal Microwave Devices

An algorithm for determining the S-parameters of 2n-terminal microwave devices from the S-parameters of six-terminal networks measured using a triple 12-terminal circuit analyzer is developed.     

Comparison of Different Measurement Protocols in Electrical Capacitance Tomography Using Simulations

A major problem in electrical process tomography is that there exist relatively few measurement variables, as compared with the desired resolution of the reconstructed image. This, in addition to the ill-behaved inverse problem involved, makes the image reconstruction problem difficult and severely underdetermined. Using more complex measurement protocols, in addition to an increased number of electrodes, introduces smaller rotational steps of the electric field. More information about the material distribution is obtained, and an increase in the image fidelity may be expected. In this paper, the image fidelity using protocol 3 is compared with the results using the conventional protocol 1. In addition, some performance metrics to assess the fidelity of the protocols are used in the final stage of the analysis. The results are based on simulations using COMSOL Multiphysics and MATLAB.     

Measurement of Refractive Index of Liquids Using Length Standards Traceable to SI Unit

Many workers have published various methods to measure refractive index of various liquids. Mostly, the measurement results are not traceable to SI units. A novel method is developed at CSIR-NPL, India (NPLI) to measure refractive of index of liquids using gauge blocks, metrological microscope and displacement laser interferometer. A vessel with flat bottom is chosen to hold the liquid under test. A pair of gauge blocks of different lengths is fixed in the vessel. The vessel is arranged under a vertically movable microscope. A calibrated displacement laser interferometer is attached to the microscope stage. The microscope is focused to the surface of gauge block before poring liquid. After poring liquid in the vessel, the microscope is moved vertically to regain the focussed image of surface of submerged gauge blocks. The measurement method is simulated mathematically. The refractive index of liquid medium is calculated using this mathematical model. Refractive index of water, isopropyl alcohol is measured. Various error contributing sources are identified. The measurement uncertainty is evaluated.     

二等雨量计量标准测量不确定度评定

本文结合自动气象站雨量传感器检定工作,运用不确定度评定与表示方法,分析其误差来源,对二等雨量计量标准测量不确定度进行了评定。     

Noncontact Material Identification and Distance Measurement Using Effective Capacitance With CdS Cells

We propose a novel noncontact sensing method for material identification and for detection of the distance between the sensor and the surface of a material by using its electrical and optical properties. In the proposed method, capacitance between the terminals of a pair of CdS cells, called the effective capacitance, is measured, and several capacitance values are obtained by changing the emission strength of the light emitting diode, thus changing the resistance value of the CdS cells. From these values, it is possible to identify the materials and to detect the distance between the CdS cells and the material. In this paper, we compare four kinds of effective capacitance measurement methods using a pair of CdS cells and describe the proposed measurement method. In addition, this paper discusses the measurement accuracy of effective capacitance values in the proposed method and demonstrates its ability to identify six material samples-clear, white, and black acrylic, clear vinyl chloride, brown bakelite, and aluminum-and to detect the distance between the CdS cells and the material.     

实施技术标准创新战略 推进企业技术进步(英文)

As a core subsidiary of China South Locomotive and Rolling Stock Industry Corporation(CSR),CSR Sifang Corporation Limited(CSR Sifang for short)is a high-speed train industrialization base,a leading design and manufacture enterprise     

恒流放电法测量超级电容器静电容量的影响因素分析与不确定度评定

静电容量是超级电容器的主要电气参数之一,相关标准中均推荐采用恒流放电法对超级电容器静电容量进行测量。介绍了恒流放电法的测量原理和测量电路,通过实验分析了放电电流、充电电流、初始电压对测量结果的影响,并对静电容量测量不确定度进行了评定。结果表明:放电电流对测量结果有较大影响,静电容量随放电电流的增大而减小;充电电流和初始电压对测量结果的影响影响较小;恒流放电法测量静电容量的相对扩展不确定度为2.2%(k=2)。     

Measurement Accuracy of Secondary Standards of Sound Pressure in Comparison to Primary Standards

The paper presents the measurement uncertainty achieved in realizing the primary standard of sound pressure at NPL, India and comparison of the uncertainties of secondary calibrations with that of primary standard. The uncertainty associated with calibration of acoustic calibrators, working standard microphones and sound pressure level measurements is discussed. A comparison of the actuator response with that taken from reciprocity setup for working standard microphones is also presented. The major focus of the present work is to highlight the traceability chain established in measurement of sound pressure level and propagation of measurement uncertainties directly from the national primary standard to field measurements, which are very rigorously conducted in transportation noise monitoring, machinery noise diagnostics, noise labeling of electrical appliances and environmental impact assessment studies w.r.t noise abatement and control.     

The Measurement of Load Coefficients of dc Resistance Standards Using ac Loading Currents

A new method of measuring the load coefficients of precision direct current standard resistors is described which has many advantages over the presently used direct current methods. Alternating current is used to provide almost all of the load required in the resistor under test while a small direct current is used in the measurement of direct current resistance changes. Problems of measuring circuit design are discussed relating to the simultaneous presence of alternating and direct currents and because of the alternating loading current supply circuit connected to the standard resistor under test. Possible sources of measurement error are considered and comparative curves of resistance change as a function of temperature and load are presented for several direct current resistance standards of differing resistance value and construction.     

Evaluation of a Capacitance Scaling System

An improved error analysis of an existing capacitance scaling system for supporting measurements of higher valued (10 nF to 100 ) ceramic-dielectric four-terminal-pair (4TP) capacitance standards over the 100-Hz to 100-kHz frequency range is described. The capacitance scaling system uses a commercial impedance (inductance-capacitance-resistance) meter and a single-decade inductive voltage divider as an impedance comparator. Four-terminal-pair capacitors in decade (10 : 1) steps from 10 nF to 100 F are measured. The system's 10 : 1 scaling error is determined using 100-pF and 1-nF air-dielectric 4TP capacitance standards with known capacitance and loss characteristics over frequency. This paper discusses the significant reductions in measurement uncertainty that were attained through the use of improved calibration standards and measurement method refinements. Details of the uncertainty analysis for a 10-nF capacitor (in the 100-Hz to 10-kHz frequency range) and verification data are presented.     

用于气固两相流在线测量的ECT电容测量电路

电容层析成像(ECT)技术是目前最具发展前景的多相流参数检测方法.介绍了12电极ECT成像系统的测量原理及设计方法.研制了一种交流激励的微电容测量电路,该电路具有较强的抗杂散电容性能、结构简单、容易实现等优点,较好地解决了电子开关的电荷注入效应对测量分辨力的影响问题.经试验证明可达到的实际分辨力为0.04fF.     

贯彻实施标准是企业标准化工作的主题

机电制造业是我国国民经济的支柱产业,是我国各行业重要的技术装备行业,其水平和能力直接影响着我国工业的总体水平。一直以来,机电行业标准化     

二维曲线自动跟踪测量的一种新算法

商品坐标测量机软件的二维曲线自动跟踪测量功能在应用中经常出现跟踪失败和采样信息不充分等问题。针对这些问题 ,提出了一种基于三次样条曲线基本性质的二维曲线自动跟踪测量算法 ,采用圆弧外插方法估算后续测量点并利用回溯方法提高跟踪测量的可靠性。这种方法还可以推广应用于曲面的扫描测量和一些特殊的三维曲线的自动跟踪测量中。文中还对测头补偿问题进行了分析 ,提出了相应的解决方法。     

Using Online Nominal Group Technique to Implement Knowledge Transfer

Presented in this study is an online Nominal Group Technique (NGT) platform for implementing knowledge transfer. A platform was developed to record the experimental experiences of thirteen Information Technology (IT) experts from academia and industry. We found that an online NGT platform could provide formal activities for promoting knowledge transfer in pursuit of consensus at a distance. Internalization of knowledge resulted from the review and rethinking process when applied to solution priorities. The results of this study have implications for users to initiate knowledge transfer at a distance for students conducting a capstone project with industry, for industry/academia research projects, and on industry projects between faculty and industry personnel. The processes of providing knowledge creation, interaction, and internalization were shown to lead to knowledge transfer for consensus building. The implementation efficiency was mainly contributed to by platform recognition, an important outcome when constructing information platforms for transferring knowledge among industry engineers, engineering students, and engineering educators.     

双谐振小电容测试方法研究

提出一种两次谐振的小电容测试方法,它能有效地抑制分布电容的影响。给出了测试系统结构和支持结论的实验数据。     

Automation and Evaluation of Two Different Techniques to Calibrate Precision Calibrators for Low Frequency Voltage Using Thermal Devices

Low frequency (LF) voltage and current are important parameters in electrical metrology. The standards for LF voltage and current are established by assigning AC–DC transfer difference to thermal devices, i.e. thermal converters or thermal transfer standard along with current shunts. Automated calibration systems have been developed based on Null method and measurement technique developed by Budovsky for calibration of precision calibrator in LF voltage and current against thermal devices. The technique based on the Algorithm developed by Dr. Ilya Budovsky (National Metrology Institute (NMI), Australia) has been compared with the conventional null technique. Indigenously developed software has been used to calibrate the precision calibrator in the entire LF voltage and current range using Holt thermal converters and current shunts. Calibration results at 1 V, 10 V in the frequency range from 10 Hz to 1 MHz as well as calibration results of 1 A in the frequency range from 40 Hz to 10 kHz are presented in this paper. These result shows that the measurement technique developed by Budovsky has reduced the complexity of AC–DC transfer measurements, measurement time and the uncertainty in measurement.     

GUM与基于观测方程的测量不确定度评估

比较了GUM系列文件与贝叶斯方法评估不确定度的过程,说明GUM是以测量方程为基础的前向分析方法,而贝叶斯分析是以观测方程为基础、以数据分析为主的一种后向不确定度评估方法。运用概率模型的描述方法对上述两种分析过程进行了分析与比较,说明了两种方法在线性测量模型的条件下,不考虑被测量先验分布时两种结果基本一致,对于非线性的测量模型,GUM S1得到的结果与一定先验分布条件下的贝叶斯分析的结果也基本一致。最后通过实例说明了该结论。     

校准件不完善对矢量网络分析仪单端口 S 参数测量引入的不确定度

通过对网络分析仪单端口 OSL 校准方法的研究,分析了校准件的不完善--开路器、短路器校准位置的不明确及校准负载的不理想等对单端口校准结果的影响,并推导出校准件实际值和理想值的偏差与校准结果之间的数学关系,结合实验数据与仿真结果对算法加以验证.