共查询到20条相似文献,搜索用时 46 毫秒
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基于实测扫频响应反推管路卡箍支承刚度及阻尼 总被引:1,自引:0,他引:1
为了建立管路系统动力学模型并分析其振动特性,需获取动载荷下卡箍支承刚度及阻尼等力学特性参数。该研究提出一种基于实测扫频响应的响应面法来反推上述参数的方法;提出了基于响应面反推管路卡箍支承刚度和阻尼的辨识算法;利用自编有限元创建了管体-卡箍系统的动力学模型,推导了管路系统振动响应;在利用响应面法的匹配计算中,进行了卡箍刚度及阻尼关于频率和对应响应的多项式拟合,并采用基本遗传算法进行了优化。在实例研究中,用提出的方法辨识出了所研究管路卡箍的具有频率依赖性的支承刚度和阻尼;将辨识值回代到分析模型中,通过比较预测的与实测的频域响应,共振频率及响应偏差均小于3%,证明了辨识结果的合理性。 相似文献
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本文研究多自由度支承系统动刚度的计算方法,并用于计算轴系临界转速。由两个自由度支承系统出发,导出求解动刚度曲线的正则化滤波方法,以获得近似最优解,推广至多自由度系统获得解析形式的三次样条和经验解,实例证明了计算方法是正确和有效的. 相似文献
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通过实测交叉梁系低阶的固有频率,以传递矩阵法为基础,由计算机代数语言推导出含待识别支承刚度的高次方程或非线性方程组,解此方程就能识别出支承刚度,并通过实验来验证该方法的有效性. 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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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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V. T. Bublik A. I. Voronin E. A. Vygovskaya V. F. Ponomarev N. Yu. Tabachkova O. V. Toropova 《Inorganic Materials》2011,47(14):1563-1568
An analysis of anisotropy of the properties of a Bi2Se0.3Te2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal
expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological
fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained
using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied. 相似文献
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O'Brien RS 《Radiation protection dosimetry》2003,105(1-4):95-100
Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides. 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