共查询到20条相似文献,搜索用时 125 毫秒
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从电磁流量计理论出发,建立插入式电磁流量计的物理模型,求出相应的电势、磁势和权函数的分布,并进行了定量计算,分析不同流场下插入式电磁流量计的输出电势差。计算研究表明,如果把电极放置于平均流速点位置,这种流量计可以测得通过管道的流量,电极位置偏差所产生的测量相对误差约为1%~2%。 相似文献
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关于污水处理厂电磁流量计在线检测方法的探讨 总被引:1,自引:0,他引:1
电磁流量计目前大多采用离线检定法,为探知现场使用条件下流量测量的准确性,需对电磁流量计进行在线检测。通过现场试验来说明采用超声波流量计对电磁流量计进行在线检测的可行性,并阐述了提高在线检测准确性的方法和在线检测的应用前景。 相似文献
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《工业计量》2017,(1)
为了研究高精度电磁流量计在不同温度下的特性变化,以山东省计量院的DN50~DN400热水流量标准装置为实验平台,对横河DN40、科隆DN80、西门子DN100三块0.2级电磁流量计进行研究。采用热水流量标准装置质量法测试电磁流量计在不同温度及流速下的仪表系数和重复性。通过实验分析得出:电磁流量计的仪表系数随介质温度的升高逐渐降低;仪表系数在高温以及低温处受影响明显,DN40电磁流量计的仪表系数本次实验高低温处最大变化量约为0.7%;在电磁流量计对应的流量范围内,仪表系数受介质流速变化的影响不超过±0.2%等。通过实验分析,对电磁流量计的特性有了深入的了解,对流量计量器具的标定以及相关的实验工作有着积极的作用。 相似文献
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醋酸生产工艺具有高温、强腐蚀性的特点,腐蚀介质种类多,腐蚀环境复杂,为满足计量需要,大多数的醋酸装置采用电磁流量计代替传统的流量计,对电磁流量计在测量过程中出现的故障,进行分析并提出一些日常维护方法。 相似文献
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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. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
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. 相似文献
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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. 相似文献
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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。 相似文献
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M. M. Gadenin 《Inorganic Materials》2013,49(15):1352-1356
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. 相似文献
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V. T. Kornienko 《Strength of Materials》1991,23(7):760-765
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. 相似文献
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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. 相似文献
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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)。 相似文献