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991.
992.
Entropy‐Based Optimal Sensor Placement for Model Identification of Periodic Structures Endowed with Bolted Joints
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Tao Yin Ka‐Veng Yuen Heung‐Fai Lam Hong‐ping Zhu 《Computer-Aided Civil and Infrastructure Engineering》2017,32(12):1007-1024
The number of sensors and the corresponding locations are very important for the information content obtained from the measured data, which is a recognized challenging problem for large‐scale structural systems. This article pays special attention to the sensor placement issues on a large‐scale periodically articulated structure representing typical pipelines to extract the most information from measured data for the purpose of model identification. The minimal model parameter estimation uncertainties quantified by the information entropy (IE) measure is taken as the optimality criterion for sensors placement. By utilizing the inherent periodicity property of this type of structure together with the Bloch theorem, a novel tailor‐made modeling approach is proposed and the computational cost required for dynamic analysis to form the IE with respect to the entire periodic structure can be dramatically reduced regardless of the number of contained periodic units. In addition, to avoid the error of dynamic modeling induced by conventional finite element method based on static shape function, the spectral element method, a highly accurate dynamic modeling method, is employed for modeling the periodic unit. Moreover, a novel discrete optimization method is developed, which is very efficient in terms of the number of function evaluations. The proposed methodology is demonstrated by both numerical and laboratory experiments conducted for a bolt‐connected periodic beam model. 相似文献
993.
Yong Yin Yinfeng Hao Yu Bai Huichun Yu 《Sensing and Instrumentation for Food Quality and Safety》2017,11(1):24-32
Fisher discriminant analysis (FDA) is a very useful pattern recognition technique widely used in electronic nose system (e-nose). However, due to its linear characteristic, the classification problems of multi-class and high-dimensional e-nose data cannot be handled effectively. Therefore, a Gaussian-based kernel FDA (KFDA) method is proposed to solve multi-class and high-dimensional classification problems of complex samples such as food classification using e-nose. The key point of the method is how to determine the Gaussian kernel parameter. Firstly, according to distance discriminant analysis viewpoint, a desired kernel matrix adapted to Gaussian kernel function can be given successfully. Secondly, an evaluation function based on Euclidean distance is established for measuring the degree of approximation between actual kernel matrix containing an unknown Gaussian kernel parameter and the desired kernel matrix so as to get an optimal solution of the parameter, and then the actual kernel matrix can be definitely determined. Finally, the principal component analysis (PCA) for the actual kernel matrix is carried out. Meanwhile, FDA for the principal component matrix generated by PCA is also implemented in succession, and the KFDA is completed. Six kinds of Chinese spirit and six kinds of Chinese vinegar samples as two classification applications were respectively carried out accurately with the KFDA method; and the KFDA method is tested to be very simple and effective. The KFDA method may be promising for complex samples classification dataset of e-nose. 相似文献
994.
995.
Fabrication of ZnS/C microsphere composites with enhanced electromagnetic wave absorption properties
Xing Honglong Wang Yin Bai Linghan Ji Xiaoli Yang Ping 《Journal of Materials Science: Materials in Electronics》2022,33(25):20021-20034
Journal of Materials Science: Materials in Electronics - For electromagnetic wave-absorbing materials, organic-derived carbon materials and metal sulfides are highly preferred. In this paper, ZnS/C... 相似文献
996.
为提高温和地区已建工程水工混凝土的抗冻性检验水平,结合该类地区广泛应用的设计抗冻等级(F50和F100),以及泵站、闸坝等典型水工建筑物普遍使用的强度等级(C25、C30和C35),设计了硬化含气量梯度变化的多种二级配混凝土。通过硬化气孔参数测试、冻融循环试验和回归分析,探讨了各参数之间的关联性和硬化含气量的控制标准;并在扬州市某泵站工程取芯试验对该标准进行可行性论证。室内试验表明,混凝土相对动弹模量与硬化含气量有着较好的对数相关关系;对于C25、C30和C35水工混凝土,F50抗冻等级的硬化含气量应分别不低于1.4%、1.1%和1.1%;F100抗冻等级的硬化含气量应分别不低于2.4%、2.4%和2.0%。工程现场取芯试验结果表明,该标准具有较强的实用性。 相似文献
997.
Wai Chung Yeong Ping Yin Lee Sok Li Lim Khai Wah Khaw Michael Boon Chong Khoo 《Quality and Reliability Engineering International》2021,37(5):2014-2033
Control charts for monitoring the coefficient of variation (γ) are useful for processes with an inconsistent mean (μ) and a standard deviation (σ) which changes with μ, by monitoring the consistency in the ratio σ over μ. The synthetic-γ chart is one of the charts proposed to monitor γ, and its attractiveness lie in waiting until a second point to fall outside the control limits before a decision is made. However, existing synthetic-γ charts do not differentiate between the points falling outside the upper control limit (UCL) and lower control limit (LCL). Hence, this paper proposes a side-sensitive synthetic-γ chart, where successive nonconforming samples must either fall above the UCL or below the LCL. Formulae to compute the average run length (ARL), the standard deviation of the run length (SDRL) and expected average run length (EARL) are derived using the Markov chain approach, and the algorithms to obtain the optimal charting parameters are proposed. Subsequently, the optimal charting parameters, ARL, SDRL and EARL values for various numerical examples are shown. Comparisons show that the side-sensitive synthetic-γ chart consistently outperforms the existing synthetic-γ chart, especially for small shifts. The proposed chart also consistently outperforms the Shewhart-γ chart, while showing comparable or better performance than the Exponentially Weighted Moving Average (EWMA) chart for most shift sizes, except for very small shifts. Finally, this paper shows the implementation of the proposed chart on an industrial example. 相似文献
998.
Mobile Networks and Applications - With the rapid development of Internet of things, the traditional city model is no longer applicable. Therefore, the emerging concept of smart city meets the... 相似文献
999.
Liu Wei Zhao Fusheng Kong Meiling Yin Songfeng Wang Huiying Liu Xiaoying 《Fire Technology》2022,58(5):2811-2823
Fire Technology - The use of perfluorinated hexanone as a fire extinguishing agent for lithium-ion batteries (LIBs) has been steadily increasing in China in recent years. It successfully handles... 相似文献
1000.