液位计标准装置的计量性能评价

液位计标准装置用于液位计的量值传递,其计量性能直接决定了液位计的检定结果,进而影响液位计的使用。对建立的三套液位计标准装置的计量性能进行评价,从引入其不确定度的各个参量定量分析其影响量,建立测量模型并计算合成不确定度,进而评价其计量性能。结果得出三套液位计标准装置的扩展不确定度分别为:差压式Urel=0. 05%、静压式U=1. 5mm、反射式U=2. 0mm(k均取2),能够较好满足工业级液位计的量传需求。     

可动液槽式液位计检定装置的研制

目前石化企业使用液位计进行液位测量过程中存在着计量交接误差问题,而且国内现有液位计检定装置存在耗水量大、操作复杂、工作效率低等缺点.因此,本文在对液位计工作原理和检定方法分析研究的基础上,成功研制出可动液槽式液位计检定装置,并提出一种基于可动液槽式原理的液位计检定方法.通过对该装置的计量性能进行实验验证,表明该方法可行,装置稳定性良好.     

一种补偿法液位计检定装置的设计与不确定度分析

随着高精度液位测量仪表的广泛应用,对液位计的量值溯源尤其是液位计检定装置的整体不确定度也有更高的要求。为解决目前采用钢直尺作为主标准器无法满足高精度液位计在JJG971-2002《液位计》中规定(整个检定设备在内的扩展不确定度U95应不超过被检液位计最大允许误差绝对值1/4至1/5的溯源要求)的问题,设计一种采用补偿微压计原理,水准头进行液位精确定位,高精度直线式感应同步器测量水准头位移量,从而准确测出液位变化量的液位计检定装置。通过对装置各部件设计结构带来的不确定度进行综合评定,完全满足检定规程中最高0.02级高精度液位计的量值溯源要求,有效补充高精度液位计的量值溯源难题,保障液位计量值溯源的准确性。     

常见油罐液位计的性能特点及选用

油罐是炼油厂、油库、油田、油品码头及石化企业必不可少的储存设备 ,罐内液体 (石油化工产品 )的测量 ,通常采用液位计。应合理选用液位计 ,以求得最合理的性能价格比。下面简单介绍常见几种液位计的性能特点 ,适用范围及一般选用原则。1　常见液位计的性能特点1 1　浮子式钢带液位计这种液位计自国外 2 0世纪 30年代开始使用以来至今仍有较高的市场占有率 ,其优点是比较直观、价格便宜 ,缺点是传动部件多 ,易发生故障 ,维护量大 ,对安装要求比较高 ,安装时需生产厂家现场指导安装。在投资有限的项目中 ,中、小型罐仍可考虑选用该液位计 ,…     

成品油检尺与雷达液位计测量的误差分析

对人工检尺和雷达液位计的计量误差进行了对比研究,建立了两者的测量不确定度模型,并分别计算了两者的测量不确定度。分析了雷达液位计测量特点、局限及误差的主要影响因素,提出相应的改进措施,实践表明能够有效提高雷达液位计的测量不确定度。     

一种立式磁致伸缩液位计校准装置的研制

作为一种高精度液位测量装置,磁致伸缩液位计应用日渐广泛。针对现有磁致伸缩液位计校准装置存在的操作复杂、设备占地面积大、精度相对较低等问题,设计了一种立式磁致伸缩液位计校准装置,采用高精密光栅尺作为测量标准,应用机械定位方法实现液位计的快速装调,采用竖直导轨系统自动实现浮子的上下定点移动,通过专用控制软件实现液位计的自动精确测量。对该装置进行测量不确定度评定,证明其具有很好的准确性与可靠性,可有效满足紧凑空间下测量范围为0~2 m的磁致伸缩液位计的校准需求,具有技术推广价值。     

液位计检定装置的研究

2004年天津市计量技术研究所研制成功了“液位计检定装置”，结合该装置的使用情况，本文对该装置如何开展一些典型的液位计检定作介绍。     

液位计示值误差测量结果的不确定度评定

本文根据国家计量技术规范JJF1059-1999国家计量检定规程JJG971-2002《液位计检定规程》对液位计示值误差测量结果不确定度进行评定.     

雷达液位计用于油罐计量

立式计量金属罐的液位计量是油品日常核查和贸易结算最重要的依据,因此寻找各种先进的罐内液位高度测量手段是有效管理、准确计量、高效运行始终追求的目标。雷达液位计以其精度高、工作稳定可靠、布网方便、适用介质范围宽而受到青睐。本文针对辽河油田常用的几种雷达液位计的计量性能、原理和布网等做简单概述。     

雷达液位计示值误差不确定度评定

雷达液位计是一种新型的液位测量仪表,本文根据国家计量技术规范JJF1059[1]1-2012《测量不确定度评定与表示》及国家计量检定规程JJG971-2002《液位计检定规程》,详细分析了雷达液位计示值误差测量过程中引入的各不确定度因素,最后给出了测量结果的扩展不确定度。     

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.     

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.     

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.     

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)。