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全站仪测距精度的校准需要在标准基线场上进行,由于野外环境不可控和气象条件波动剧烈,因此判断全站仪的测量结果的可靠程度具有重要意义。为了解决全站仪测距不确定度评定模型的非线性和输入量强相关等问题,本文首先采用了自适应蒙特卡洛法进行不确定度评定,然后与GUM的不确定度评定结果进行对比,当测距距离为1 176 m时,自适应蒙特卡洛法评定的不确定度结果为2.2 mm,GUM为2.6 mm,结果显示两种不确定度评定方法的测量结果均在合理预期之内,且自适应蒙特卡洛法评定的不确定度置信区间更窄。自适应蒙特卡洛法结合了大量数据样本和自适应优化仿真次数的优势,不仅对全站仪测距过程中的各项误差源引入的不确定度分量评估更为全面,而且在保证了全站仪测距不确定度评定结果准确的同时,相比于蒙特卡洛法节约了70%的样本数量。 相似文献
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在350kHz~30MHz频段内,为了准确得到环天线所处位置的场强,环天线的天线系数需要校准。三天线法是一种校准天线系数的绝对方法,需要3个环天线,两两组对测量,且不需要任何参考标准。介绍了三天线法校准环天线的原理,基于矢量网络分析仪建立校准系统,并评定校准系统的测量结果不确定度。基于K(i,j)的计算公式复杂,很难计算出其引入的不确定度,因此采用数字电磁学代码(NEC)建模评定K(i,j)的不确定度。评定结果表明,在350kHz~30MHz频段内4个典型频点的扩展不确定度小于0.81dB(k=2)。 相似文献
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温度试验箱的校准包括温度均匀度、温度波动度和温度偏差三个基本项目。测量系统由若干支铂电阻传感器和数据采集器构成,测量系统的测量不确定度必须满足国家有关规定。由于铂电阻都有自己的电阻-温度特性,并且需要考虑它们之间的相关性,造成测量不确定度的计算比较复杂,GUM的框架式分析法(Analytical Method)对于非线性测量很不实用,蒙特卡洛法(Monte Carlo Method)可以通过模型仿真避免这些困难。 相似文献
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当采用蒙特卡洛法评定测量不确定度考虑输入量相关性时,需基于Nataf逆变换产生服从任意边缘概率分布的相关多维随机变量。为了解决Nataf逆变换过程中输入量相关系数矩阵非正定时,无法产生线性变换矩阵的问题,提出了基于Barzilai-Borwein梯度法的迭代修正算法。进而探讨了输入量服从非正态分布且相关的蒙特卡洛法实施步骤。最后,采用提出的迭代修正算法并基于Nataf逆变换的蒙特卡洛方法,对高速轮轨试验台轮轨纵向蠕滑率不确定度进行了评定,验证了该算法的可行性及有效性。 相似文献
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为准确测量、计算得到烟气再循环率,在燃气组分及浓度不变的情况下,基于化学反应平衡方程式推导得到烟气再循环率的计算公式,进而提出测量燃气锅炉烟气氧浓度和烟气-空气混合气氧浓度的双氧法。为定量分析测量结果的质量,基于国标中的GUM法对双氧法进行不确定度评定,并根据不确定度要求为仪器选择提出指导意见。研究发现,当烟气氧浓度测量结果为1.91%、混合气氧浓度测量结果为18.64%时,通过双氧法计算烟气再循环率R为13.45%,扩展不确定度为1.56%。混合气氧浓度测量不确定度对双氧法扩展不确定度影响很大,在选择测量仪器时,混合气氧浓度测量仪器的扩展不确定度可小于烟气氧浓度测量仪器。 相似文献
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Augutis V.S. Nakutis Z. Ramanauskas R. 《IEEE transactions on instrumentation and measurement》2009,58(2):337-341
Barkhausen emission (BE) is a well-known phenomenon used in nondestructive testing techniques of ferromagnetic materials. The weaknesses of methods based on BE are related to the difficulties of ensuring measurement reproducibility because of the influence of the specimen on the measurement channel. In this paper, we propose a method of sensor calibration prior to measurement. To implement the calibration, a BE sensor is equipped with an additional calibration coil. The electrical pulse induced in the calibration coil is then used to reconstruct measured magnetic field pulses at the specimen surface. 相似文献
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Bertocco M. Sona A. Zanchetta P. 《IEEE transactions on instrumentation and measurement》2007,56(4):1165-1170
This paper discusses issues in the uncertainty of power measurement performed with a superheterodyne spectrum analyzer. In particular, the channel power technique is considered, and an original and effective method is proposed based on the "Guide to the Expression of Uncertainty in Measurement" for the uncertainty evaluation of channel power measurement. The method is based on the measurement of some suitable parameters associated to the input signal's spectrum and the use of a proper postprocessing formula. It allows a user to greatly simplify the computation of measurement uncertainty without loss of accuracy. The effectiveness of the method is verified experimentally. In particular, experiments are performed involving both laboratory- generated signals and some typical real-world digital communication signals. Helpful information and hints for the optimization of the spectrum analyzer setup and the reduction of uncertainty are Anally provided. 相似文献
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J. V. Pearce P. M. Harris J. C. Greenwood 《International Journal of Thermophysics》2010,31(8-9):1517-1526
Two methods for evaluating thermocouple calibration uncertainty over the temperature range of the calibration are presented, when the thermocouple is calibrated at only a few temperatures. The evaluation of the uncertainty at fixed-point temperatures is well established, but it is often not clear how the uncertainty arising from interpolation between fixed points can be determined. We present a conventional method, based on that described in the “Guide to the expression of uncertainty in measurement” (GUM), and a numerically-based Monte Carlo method, for quantifying the calibration uncertainty arising from the use of an interpolating polynomial defined by calibration data. The two methods are compared and found to be in excellent agreement, but the Monte Carlo method is, in general, more flexible, e.g., when measurements are described by non-normal distributions. 相似文献
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KNAPP W BRINGMANN B 《纳米技术与精密工程》2005,3(4):249-256
机床轴沿轴向运动的直线度是最重要的性能指标.描述了不同的直线度测量方法(直尺法、钢丝绳法、激光干涉仪法、局部垂直度测量及球板和球杆法等),并讨论了这些方法对测量移动长度超过2000 mm的机床的适用性.详细叙述了无重叠的球板拼接,估计了测量的不确定度,测量结果不确定度U为3.4μm(因子κ=2).给出了减小主要影响测量不确定度,也就是影响机床轴重复性的主要因素的一些可能性.示出了500mm×500mm球板拼接测量,并且和轴向移动量900mm的比较仪进行了比对,两种测量结果的偏差小于0.6μm.因此不会超出原有的测量不确定度范围.球板拼接法也可应用于大距离移动中的垂直度测量.无论是利用垂直平面进行测量或者用近来引进的精密三维机床检测,无重叠的球板拼接均可用于水平和垂直的直线度测量,还可用于定位、倾斜、俯视及偏转等方面的测量. 相似文献
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A new method to calibrate the autocollimator with small angle measurement range has been developed. This method used a system based on rotary encoder for angle measurements with self-calibration function (SelfA47). The SelfA47 has 18,000 graduation lines with angle interval of 0.02°, corresponds to 72 arcsec. Thereby this system cannot be used to calibrate the autocollimator with measurement range <72 arcsec. On the other hand, SelfA47 can be used to calibrate an electronic level. The deviation of electronic level shaped linear gradient. Therefore a small nominal gradient of electronic level can be approximated by interpolation. Since the gradient of a curve corresponds to the angle quantities, it is feasible to calibrate the autocollimator with nominal angle <72 arcsec using SelfA47 and an electronic level. In this proposed method, SelfA47 is placed horizontally on the same plane with electronic level and mirror reflector position. The electronic level value that have been corrected by SelfA47 is used as a reference. This reference value was converted to the angle, thus the angle deviation of autocollimator can be determined. The prominent uncertainty of angle measurement using this new technique derived from the uncertainty of electronic level and rotary encoder. Using this method, the expanded uncertainty of 0.36 arcsec is obtained from calibration of autocollimator with measuring range of ±20 arcsec and it is consistent statistically with the manufacturer calibration result shown by E n value is <1. In conclusion, this approach method can be applied to calibrate the autocollimator with a resolution smaller than SelfA47 as standard, but it is not recommended for the calibration of highly accurate autocollimator. 相似文献
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研究了坐标测量机(CMM)尺寸测量的不确定度评定方法。建立了符合ISO国际标准的测量不确定度评定黑箱模型。利用测量系统分析的方法,对6项量值特性指标引入的不确定度分量进行量化分析或实验标定,依据产品几何技术规范给出了各不确定度分量的评定模型。最后,通过工件直径测量的不确定度评定实例验证该方法的可行性。实验结果表明CMM尺寸测量的不确定度主要来源是偏倚和线性,不确定度分量为1.88μm,是所有其他分量合成的2倍以上,而温度补偿引入的不确定度分量仅为0.04μm,在实际测量中可忽略不计。 相似文献
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激光跟踪仪测量曲面的测量不确定度研究 总被引:4,自引:0,他引:4
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. 相似文献