Precise Measurement of Isotope Ratios with a Double-Focusing Magnetic Sector ICP Mass Spectrometer

The potential of a commercially available double-focusing magnetic sector ICP mass spectrometer (Element, Finnigan MAT, Bremen, Germany) for precise isotope ratio measurement at the low-resolution setting (R = 300) was evaluated. Optimization of scanning conditions led to a relative standard deviation for a set of 10 consecutive 2 min measurements of ～0.1% ((206)Pb(+)/(207)Pb(+)) at signal intensities of ～200?000 counts/s (peak height). This compares favorably with the best values ever reported for quadrupole ICPMS and barely exceeds the theoretical value (counting statistics). Increasing the signal intensity to values ≥500?000 counts/s (peak height) resulted in a further reduction of the RSDs obtained (for both (25)Mg(+)/(26)Mg(+) and (206)Pb(+)/(207)Pb(+)) to typically 0.04%. These figures are remarkably better than those reported for commercially available quadrupole ICPMS systems. This improvement significantly reduces the difference between isotope ratio precision of ICPMS on one hand and those of thermal ionization mass spectrometry and plasma source multiple collector mass spectrometry on the other.     

高精度直径测量技术研究的新进展

直径是几何量测量的重要参量之一,无论工业应用还是在计量研究领域,探索高精度圆柱直径的测量方法具有重要的科学价值和应用前景。本文介绍了国内外研究机构在高精度直径测量技术领域取得的新成果,及各种测量方法的关键技术及其仪器在结构设计、光学设计等方面的特点。并根据目前直径测量技术的发展状况讨论了未来高精度直径测量技术的发展和研究趋势。     

精密多功能恒流源

本阐述精密恒流源的工作原理、性能特点以及用该恒流源和数字电压表代替比较电桥检定直流电阻仪器不确定度的理论分析和结果比对。     

弹簧管式精密压力表测量结果不确定度评定

本文根据JJF1059-1999《测量不确定度评定与表示》的要求,对弹簧管式精密压力表测量结果的不确定度进行评定,为精密表的校准工作提供方法。     

精密时间测量技术

时间间隔的测量是时频信号研究的基础,已经被越来越广泛的应用于科学试验和工程实践等各个领域,测量精度的提高是迫切需要解决的问题。本文介绍了脉冲计数法以及用于测量其原理误差的国内外常用精密时间间隔测量方法,分析了各自的优缺点以及误差,并指出其发展趋势,为新方法的研究提供参考。     

温曲率精密测量技术及自动化装置的研制

根据相关国家检测标准要求,以光栅位移传感器为基础,设计了自动金属复合材料精密测量装置.实现了对金属复合材料温曲率的自动测量,通过RS-232接口实时传输数据到计算机,并分析、处理检测结果和自动生成检测报表.测试结果表明温曲率准确度达到4μm.     

高精度高分辨力时间间隔测量的技术实现

介绍1 ns分辨力时间间隔测量的技术实现和总体方案设计,并对高分辨力频率测量所采用的模拟内插技术和实现的技术途径进行了简要分析.研究证明采用模拟内差计数方法能够满足高精度、高分辨力的时差测量,提高实现1 ns的时间间隔测量能力.     

Precise Current Regulation with a Transductor

It has been possible to achieve five parts per million current stability for at least 10 minutes in a 10 kW power supply by using a four-core transductor as a current-sensing device. This fourcore transductor circuit eliminates excitation and magnetization ripple from the output terminals and has a transfer function which is flat up to several kilocycles. The transductor has wide range and is able to regulate current over more than a hundred-to-one range. The transductor assembly is simple, rugged, relatively inexpensive, and requires no special construction techniques.     

光谱法精密测厚的应用设计

介绍了利用激光光谱分析法测量介质厚度的一种高精度测量方法,与一般的测厚方法不同,测量越薄的介质.精度越高,并解释了其原理.通过激光垂直照射平板基体上的介质,利用光谱仪分析仪来精确测定相邻带波数差△(1/λ),利用简洁、方便的检测过程和计算,精确地得到介质的厚度.     

盲孔深度的精确测量方法研究

当盲孔深度允差在微米量级,且其深度是相对某基准面而言时,这种深度测量一直是当前精密测量中的一个难点。根据被测对象的实际安装工况,设计出一种非接触式的多传感器组合测量法。组合测量克服了单一传感器数据的片面性和不确定性,利用多传感器对环境敏感所产生漂移的同向性抑制了单一传感器数据的漂移,提高了测量的稳定性,克服了单一传感器无法进行形位误差测量的缺陷。实验证明了该方法的可行性,测量精度优于2μm。     

直流偏移的测量不确定度

介绍了用4参数正弦波最小二乘拟合法评价线性测量系统直流偏移指标时,测量不确定度分析和评价过程．通过使用国军标GJB 3756-1999“测量不确定度的表述及评定”中推荐的方法,讨论了影响评价结果不确定度的几个主要误差来源,包括信号源误差、采集序列的谐波失真、采集序列的噪声及非谐波失真、采集序列中信号周期的抖动、软件拟合运算误差的影响等,给出了直流偏移的测量不确定度及减小直流偏移指标评价不确定度的主要措施．在一个实际评价例子上,给出了直流偏移指标不确定度评价结果,表明该过程的正确性和切实可行性．该过程及结论可应用在对于计量标准进行直流偏移指标的不确定度分析上,也可用于估计直流偏移指标本身的不确定度．     

The Application of the Compensated Current Comparator to the Calibration of Current Transformers at Ratios Less than Unity

A technique is described for extending the range of the compensated current comparator so that it may be used for calibrating current transformers at ratios both greater and less than 1/1. The concept of providing compensation windings for both the primary and secondary ratio windings is introduced and a new method of correcting for the capacitance error due to burden is presented. Details on how a compensated current comparator previously developed for ratios from 1/1 to 240/1 may be adapted for this purpose are discussed and results of measurements at ratios down to 0.01/1 with this comparator are given.     

The Precise Measurement of RF Power and Voltage Using Coaxial Calorimeters and Microcalorimeters

Automated calorimeters and microcalorimeters used by the CSIRO Division of Applied Physics as primary standards of radio frequency power and voltage and for measuring the effective efficiency of bolometer mounts are described. Methods for evaluating corrections from computer models of the thermal and electrical circuits and results of measurements and intercomparisons are presented.     

金属箔汽化电流的测量

目的　提供一种冲击电流的测量方法并用实际测量结果验证有关经验模型的实用性 .方法　采用了罗果夫斯基线圈 ,为保证测量结果的有效性 ,对测量线圈进行标定的同时 ,采取了抑制干扰的措施 ,并对短路放电条件下的测量结果进行了理论验证 .结果　对金属箔的汽化电流进行了测量 ,并与经验模型的计算结果进行了对比 .结论　证实了测量结果的有效性和所述经验模型的实用性     

The Application of Current Comparators to the Calibration of Current Transformers at Ratios up to 36000/5 Amperes

The design and construction of a multiratio, 36 000-ampex e compensated current comparator and the technique by which it may be cascaded with a second multiratio comparator to calibrate, with a single balance, power frequency current transformers at ratios up to 7200/1 are described. The first comparator has a distributed, single-turn primary winding and a sectionalized 1200-turn secondary winding that may be series-paralleled to obtain eight ratios from 120/1 to 1200/1. A 300-kVA 1100-volt transformer is included in the single primary turn to provide the power required for the calibrations. In size the device is 40 inches in diameter and 20 inches in height, and its weight is 2700 lb. The two comparators are cascaded at nominal currents up to 30 amperes by connecting the secondary winding of the first comparator to the primary winding of the second and by making corresponding interconnections between the two compensation windings. At balance, the actual current ratio of the standard composed of the two comparators in cascade, or the first comparator alone, differs from the corresponding turns ratio by no more than a part per million (ppm).     

基于激光干涉法精密测量材料线膨胀系数装置的研究

阐述了中国计量科学研究院自行设计和研制的基于激光干涉法材料线膨胀系数测量的装置.该装置采用单频激光干涉法测量样品长度变化.为了消除样品自重带来的影响,进行了新的光路设计,以实现材料线膨胀系数的绝对测量,其分辨率小于1 nm.在常温下采用美国国家标准技术研究院(NIST)标准参考物质硼硅酸玻璃进行了测试,测得材料线膨胀系数与NIST公布值的相对偏差在1.2%以内,结果证明,该测量装置的性能是可靠的.     

A Standard Attenuator and the Precise Measurement of Attenuation

An attenuator calibration system is described consisting of a waveguide-beyond-cutoff attenuator operating at 31.25 Mc and electronic equipment designed for parallel-substitution, series-substitution, and heterodyne measurements. Radio-frequency power is supplied by a crystal-controlled signal generator, stabilized so that variations in the power output do not exceed 0.001 db per hour. Measurements of a 10-db step made by the standard attenuator, and by two other methods, agree to within 0.001 db. A number of possible sources of error are examined including nonlinearity in microwave mixers.