排序方式: 共有54条查询结果,搜索用时 15 毫秒
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基于梁横向开裂纹的线性扭转弹簧模型,给出了具有任意裂纹数目的简支外伸梁弯曲挠度的显式解析解,研究了集中载荷作用下简支外伸梁裂纹诱导弦挠度函数的性质,给出了裂纹位置和裂纹等效扭转弹簧柔度的近似表达式,从而实现了梁横向裂纹位置及裂纹损伤程度的识别.在此基础上,为利用裂纹梁的测量挠度识别裂纹损伤,提出了分段线性函数的最佳拟合法,实现了简支外伸梁裂纹的损伤参数识别.通过数值试验验证了该识别方法的适用性和可靠性,考察了识别结果对梁挠度测量误差和裂纹深度的敏感性,结果表明随着挠度测量误差的增大,裂纹损伤参数识别误差增大,但裂纹损伤识别方法具有较强的鲁棒性,在工程实际中具有一定的应用性. 相似文献
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弦长度分布(chord length distribution, 简称CLD)可以用来描述几何对象(球形颗粒、柱状孔、薄片等)的大小、形状和空间排布等特点. 原理上, 弦长度分布正比于由小角散射所得的相关函数的二次微分, 因此可以由相对散射强度进行计算. 在结构研究中, 将实验所得弦长度分布与理论计算某种确定几何体所得高度准确的弦长度分布进行比较, 可以获知对象的特征几何结构. 本文以中孔氧化硅分子筛为研究对象, 介绍了弦长度分布的计算方法, 以此精确计算了中孔分子筛的孔径分布, 得到了分子筛表面有机官能化对孔径的影响规律. 相似文献
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为研究轴对称凸域的包含测度,以等腰梯形域为例,采用直线的广义法式方程,给出了等腰梯形域的广义支持函数与限弦函数的解析式。采用限弦函数法,得到了等腰梯形域的包含测度,并取消了“等腰梯形的高不超过梯形的最短底边长”这一限制条件。 相似文献
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Planar graphs with maximum degree Δ ⩾ 8 and without 5- or 6-cycles with chords are proved to be (δ + 1)-totally-colorable.
This work was supported by Natural Science Foundation of Ministry of Education of Zhejiang Province, China (Grant No. 20070441) 相似文献
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Polycrystalline spherulites of L‐glutamic acid have been crystallized by pH‐shift precipitation from stirred aqueous solutions. The time dependent behaviour of the spherulites has been studied during the crystallization process and batch filtration tests have been performed. It has been shown that the FBRM mean chord length of the investigated spherulites decreases in the course of time. The fact that the size reduction progresses faster at higher temperature and the solubility of resuspended polycrystalline particles decreasing with time, implies an ageing mechanism to be responsible for the observed changes in the particle size. It has been shown that the surface area decreases with time, ruling out particle breakage as a possible explanation for the decrease in particle size. XRD and Raman studies of L‐glutamic acid, however, show only marginal differences in the crystalline structure of particles obtained from different time stages. The ageing may occur due to several different mechanisms like phase transformation and Ostwald ripening. L‐glutamic acid spherulites after 3 h exhibit a 3‐fold higher value for the cake resistance as compared to particles after 0.5 h. However, particles obtained after 22 h exhibit an 8‐fold lower cake resistance as compared to the initially obtained spherulites, The increase in the cake resistance is attributed to the appearance of small plate‐like crystals and a change in the interaction between the crystal surface and the solution. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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讨论了音乐识别领域中和弦的四种不同识别方法,给出了基于PCP特征的和弦识别算法.使用PCP作为和弦的特征作为输入送至隐马尔可夫模型中训练,利用Baum-Welch算法估计模型参数,通过Viterbi算法得到正确和弦.通过实验获得了76%的识别率,验证了该算法的可行性. 相似文献
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Norbert Kail Heiko Briesen Wolfgang Marquardt 《Particle & Particle Systems Characterization》2007,24(3):184-192
In the past decade the use of focused beam reflectance measurements (FBRM) has been established as an on line and in situ particle characterization technique. However, a model is required to obtain full information from the FBRM signal and to compare the results to other measurement techniques. Different modeling approaches can be found in the literature. All of these assume a laser focus of zero extension, motionless particles and fully opaque particles. It is shown in this work that these assumptions do not hold even for ideally spherical particles. For large, opaque particles, the particle velocity and a depth dependent laser velocity have to be considered. For highly transparent particles, backscattering only occurs near the edges of a crystal. Consequently, two more refined modeling approaches – the velocity model and the edge scattering model – based on Monte‐Carlo techniques are developed and verified in this work. 相似文献