比长基线长度的测量不确定度评定

一、概述 比长基线是检定光电测距仪、全站型电子速测仪等测绘仪器的主要计量标准器。比长基线长度的测量依据是GB16789—1997《比长基线测量规范》。比长基线长度的测量采用6根24m因瓦基线尺将比长基线分为距离相等的3节进行测量，每一节用4根因瓦基线尺测量，2根用于往测，2根用于返测。各段每根因瓦尺读数之和加入温度改正系数，尺长改正数，倾斜改正后，即为每根因瓦线尺算得的段长。各段长度相加即为基线全长长度。     

野外大长度标准器—24 m因瓦基线尺量值的可靠性

野外主要标准基线场的长度量值,均采用24 m因瓦基线尺进行测量,其测量结果相对标准偏差一般优于5×10-7,基线场的长度量值(基线量值)的测量误差除野外的测量误差外,主要有基线尺本身的长度测量不确定度和温度线膨胀系数测量不确定度.24 m光学机械比较仪是利用比较测量的原理室内检测基线尺长度的标准装置,其测量结果不确定度U99优于15μm/24m.通过分析光学机械比较仪检测基线尺的不确定度和检测数据,评估基线尺量值的可靠性.     

全站仪测距常数分离检定研究

全站仪测距常数直接影响距离测量结果的准确度,传统的六段比较法解算的加乘常数是相瓦影响的.分离检定法分步解算加乘常数,避免了加乘常数解算的相互影响.结合测距常数的特点和检定方法,编写程序分别用六段比较法和分离检定法对某测距基线近一年的全站仪测距常数检定数据进行了计算,并分析了六段比较法和分离检定对测距常数的影响及其规律.     

基于光路折叠的室内基线场误差分析方法研究

为了有效开展长距离光电测距类仪器的室内检定工作,在50m高精度导轨上利用1组平面反射镜进行光路折叠,搭建了100m室内基线场。对基线系统的测量误差进行了分析,考虑各项误差的调整精度,将误差分析结果应用到实际光路调整过程中,分析得到对基线长度影响更显著的误差量,并对其进行了控制和调整,提高测量光路的平行性调整精度,最后选择双频激光干涉仪作为长度基准开展验证实验。实验结果表明:通过光路折叠方法可以实现2倍光程倍增,基线系统的精度较高,可进行连续测量,有效地解决了室内基线建立过程中所存在的检测效率低、可重复性差等技术问题。     

全站仪检定的一种新方法

依照JJG 703—2003的方法对全站仪测距部分进行检定,存在着标准器基线场选址建设困难、检定过程繁琐、数据后处理复杂等难点。本文在分析测距误差的基础上,提出了由基线场通过21段组合比较法量传到高等级全站仪,再通过直接比较法量传到低等级全站仪的检定方案。实验结果表明该方法检定效率高、操作方便,检定结果准确可靠。     

样条函数在激光跟踪仪测距补偿中的应用

激光跟踪仪测距精度取决于激光干涉仪(IFM)和激光绝对测距仪(ADM)的精度,就目前技术水平而言,IFM测距精度远高于ADM测距精度,因此需要对ADM测距误差进行修正。本文采用三次样条函数对激光跟踪仪全程ADM测距误差进行修正,并与线性误差修正方法进行了对比,结果显示三次样条函数能够更好地拟合误差曲线,改善修正后残余误差的均方差,均方差为0.007 mm,优于最小二乘直线拟合,从而提高激光跟踪仪测距精度和空间测量精度。     

论对全站型电子速测仪测距检测数据处理的合理性

JJG100-2003<全站型电子速测仪>检定规程规定,检定全站型电子速测仪(以下简称"全站仪")的"测距综合标准差",须先在基线场内测量21段不同的标准基线段的长度(以下简称"测量值"),然后根据它们与标准基线段长度(以下简称"标准值")的差计算加常数和乘常数.然后再用加、乘常数对这些测量值进行修正,再根据这些修正过的测量值与标准值的差,计算测距标准偏差的固定部分口和测距标准偏差的比例系数b,从而计算"测距综合标准差".     

1200米长度基线场设计和建造

为满足测绘仪器的检定包括常规测绘仪器长度的检定以及全站仪、全球导航卫星系统(GNSS)接收机等高科技测绘仪器,潍坊市计量测试所建立室外1 200米长度基线场。文章对基线场的设计和建造进行了概述,给出了长度基线场设计原则,依据要求对场地选址进行了探讨,并详细描述了基线场观测墩的布设规划和观测墩的具体规格,以及基线场设计达到的最终技术指标等。同时介绍了基线场建造过程为保证达到设计要求所运用的方法和技术,对设计和建造长度基线场具有参考意义。     

全站仪加乘常数的校准方法

现行的光电测距仪检定规程规定加乘常数的检定采用野外基线比较法进行,由于目前大量的全站仪需此方面的工作,强度很大。本文通过对基线比较法的分析和一些试验结果,提出了一种基线比较消去法来计算加乘常数及其测量标准偏差。在不影响其测量结果的情况下,对于给定的基线,可以减少测量基线段数,从而提高工作效率。     

全站仪周期误差检定的探讨

本文介绍了全站仪周期误差检定装置的因瓦标准尺长度最佳确定 ,及提高棱镜对中精度的方法     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。