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G. N. Solopchenko 《Measurement Techniques》1996,39(10):988-992
We compare two distribution-independent methods for determining confidence intervals for the characteristics of systematic
and random error and for interquantile intervals of complete error, the methods compared are the bootstrap and L0 methods. We compare the properties of computational difficulty and reliability. Both methods have approximately the same
reliability, but the bootstrap methods requires 4–5 times as much work.
Translated from Izmiritel'naya Tekhnika, No. 10, pp. 9–12, October, 1996. 相似文献
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采用Kane方法建立风力机系统动力学模型,并使用假设模态离散化方法对其进行柔性化。结合修正的BEM理论计算得到的风轮气动载荷,并在Fortran环境下编程建立风力机整机的系统动力学数学模型,完成对风力机的随机响应分析。以某型2.5MW风力发电机组为研究对象进行分析计算,将分析数据同国际权威计算软件GH Bladed数据比较。比较表明,该分析模型可以较好的模拟风力机的动力学特性,同时兼顾了较少建模计算时间和较高分析精度两个优点,近而验证采用假设模态法进行风力机动力学分析是一种行之有效的方法。 相似文献
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统计能量分析(SEA)是解决复杂结构高频动力学问题的有效方法,正确估计统计能量分析参数则是利用该方法得到可靠分析结果的关键。论文基于特征系统实现算法(ERA)提出一种确定统计能量分析参数的方法,首先应用ERA辨识统计能量分析系统的最小阶功率流模型,然后利用辨识模型的特征对修正初始统计能量分析模型,进而得到较精确、可靠的参数。三子系统SEA模型的仿真结果验证了利用该方法得到的统计能量分析参数的正确性,而且在一定测量噪声干扰下仍能保持较好的精度。最后,对铝蜂窝夹层结构小卫星的SEA模型进行了仿真,进一步验证了算法可应用于复杂结构的统计能量分析参数识别。 相似文献
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《中国测试》2016,(6):90-94
工程实际中测得的滚动轴承信号往往含有大量的噪声,这使得轴承故障特征淹没在噪声中难以被提取。针对这一问题,提出一种基于随机噪声统计特性与局部均值分解(local mean decomposition,LMD)理论相结合的滚动轴承故障诊断方法。首先,利用LMD将原信号分解,得到若干乘积函数(production function,PF)分量;其次,将第一阶PF分量随机排序,与剩余PF分量相加;然后,对第2步进行P次循环,求平均;最后,把第3步得到的信号作为原信号,重复第1、2步Q次,对得到的信号进行频谱分析,提取故障特征。通过对仿真信号和实验台轴承实验信号进行分析研究表明,该方法可准确诊断滚动轴承元件故障,具有有效性。 相似文献
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The present practice for uncertainty expression and estimation in measurement, endorsed in the IEC-ISO Guide to the Expression of Uncertainty in Measurement, is based on a statistical approach, which is also the basis for the Monte Carlo method generally employed to overcome the problems met in the strict application of the guide. More recently, methods based on the fuzzy theory have been proposed too, with encouraging results. This paper compares the results obtained, in the expression of uncertainty, by the use of the Monte Carlo method and the random-fuzzy variable method. Both methods are applied to a real, digital signal processing-based instrument for electric power quality measurement, and the obtained results are compared and discussed. 相似文献
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Norbert Büchter Ekkehard Ramm Deane Roehl 《International journal for numerical methods in engineering》1994,37(15):2551-2568
Conventional shell formulations, such as 3- or 5-parameter theories or even 6-parameter theories including the thickness change as extra parameter, require a condensation of the constitutive law in order to avoid a significant error due to the assumption of a linear displacement field across the thickness. This means that the normal stress in thickness direction has to either vanish or be constant. In general, these extra constraints cannot be satisfied explicitly or they Sead to elaborate strain expressions. The main objective of the present study is to introduce directly a complete 3-D constitutive law without modification. Therefore, a 7-parameter theory is utilized which includes a linear varying thickness stretch as extra variable allowing also large strain effects. In order to preserve the basic features of a displacement formulation the extra strain term is incorporated via the enhanced assumed strain concept recently proposed by Simo and Rifai to improve the performance of finite elements. Since the extra strain parameter can be eliminated on the element level after discretization, the formulation preserves the formal structure of a 6-parameter shell theory. The resulting hybrid-mixed shell formulation is applied to large deformation problems with hyperelasticity, small and large strain plasticity. 相似文献
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A combination of phase-shift with gray-code light projection into a three-dimensional vision system based on the projection of structured light is presented. The gray-code method is exploited to detect without ambiguity even marked surface discontinuities, whereas the phase-shift technique allows the measurement of fine surface details. The system shows excellent linearity. An overall mean value of the measurement error equal to 40 microm, with a variability of approximately +/-35 microm, corresponding to 0.06% of full scale, has been estimated. The implementation of the technique is discussed, the analysis of the systematic errors is presented in detail, and the calibration procedure designed to determine the optimal setting of the measurement parameters is illustrated. 相似文献
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Measurement Techniques - 相似文献
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Results are presented from an evaluation of the accuracy of the solution of an inverse heat-conduction problem for an infinite plate with nonsymmetrical heat-transfer boundary conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 3, pp. 400–403, March, 1989. 相似文献