共查询到20条相似文献,搜索用时 62 毫秒
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一、瞬时开关动作特性校验台内部结构的回路电阻分析瞬时开关动作特性校验台(以下简称"校验台")的回路电阻主要是由开关动、静触头的固有电阻和接触电阻产生的,其中固有电阻是指无接触部件的导电回路的电阻,接触电阻是指连接部件的附加电阻,而且它对整个回路电阻影响最大。接触电阻又分为表面 相似文献
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在ZF6—252GIS4000A共箱母线(改进型)新产品试制的过程中,通过对温升试验结果的分析,结合参考文献中介绍的知识及以往的设计经验,对共箱母线导电回路的组成零部件,进行了一些改进。这些改进以降低导体和电接触位置的电阻为侧重点,并且改进的效果得到试验的验证,简要的说明了设计结构与产品回路电阻以及温升之间的一些关系。 相似文献
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通过分析接触电阻产生的原因及其影响因素来认识准确测量接触电阻的意义。从理论出发介绍接触电阻的测量方法,介绍了四线端子法的测量原理及优势。 相似文献
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大面积导电材料的电阻测量多用四线制伏一安法,如图1所示。表面看,准确测量Ⅰ和Ux不应该有什么困难。但是当被测材料的几何尺寸不能满足有关电流端与电位端之间距离的规定时,按常规方法测出民的数值可能不准确,这里很关键的一点是需要正确选择测试点的位置。当不考虑材料的厚度,则在一块板状材料上可供选择作为测试点的方案之一,如图2所示。由于不仅沿材料的PQ方向存在横向电阻,而且活P-M方向也有纵向电阻。因此,由电流入B端通人电流Ⅰ后,由于A、P(Q、B)之间的距离有限,纵向电阻的存在造成了导体中电流密度呈不均匀分布,… 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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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
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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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