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排序方式: 共有1005条查询结果,搜索用时 31 毫秒
71.
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Jun Feng YanLin Ye Biao Yang ChengJian Lin HuiMin Jia DanYang Pang ZhiHuan Li JianLing Lou QiTe Li XiaoFei Yang Jing Li HongLiang Zang Qiang Liu Wei Jiang ChenGuang Li Yang Liu ZhiQiang Chen HongYi Wu ChunGuang Wang Wei Liu Xiang Wang JingJing Li DiWen Luo Ying Jiang ShiWei Bai JinYan Xu NanRu Ma LiJie Sun DongXi Wang 《中国科学:物理学 力学 天文学(英文版)》2019,(1)
The inelastic excitations and cluster decay of ~(13)C have been measured using the reaction,9Be(~(13)C, ~(13)C* →~9Be + α)~9Be. We observe strong excitation to the 14.3-MeV(1/2-) resonant state from the cluster-decay channel, leading to an enhanced monopole matrix element of(6.3 ± 0.6) fm~2. This large cluster-related monopole strength is a clear indication of the cluster-structure domination of this state and is consistent with the recent prediction of the orthogonality condition model(OCM). It would be interesting to further explore the three-center molecular rotational band that is initiated from the observed band-head. 相似文献
73.
为了深入研究反应堆结构中诸如燃料棒、蒸汽发生器传热管束等的流致振动问题,利用有限体积法离散大涡模拟的流体控制方程,利用有限元方法离散结构动力学方程,并结合动网格技术建立了模拟双向流固耦合作用的三维数值模型,实现了弹性管与弹性管之间以及弹性管与湍流流场之间的交互作用。利用该模型分别研究了节径比P/D为1.2、1.6、2.0、3.0、4.0的两交错排列弹性管在横向湍流作用下的振动响应及流场特性。通过分析发现:两交错排列弹性管的运动轨迹和尾涡结构与其间距、流速密切相关;两交错管的临界节径比为2.0;P/D=3.0时双管的临界流速Upr=2.2,P/D=1.6时双管的临界流速Upr=4.0。 相似文献
74.
Laser-induced Fluorescence Spectroscopy of NiS: Identification of a Low-lying Electronic State 下载免费PDF全文
Laser-induced fluorescence excitation spectra of jet-cooled NiS molecules were recorded in the energy range of 12200-13550 cm-1. Four vibronic bands with rotational structure have been observed and assigned to the [12.4]3∑0- -X3∑0- transition progression. The relevant rotational constants, significant isotopic shifts, and (equilibrium) molecular parameters have been determined. In addition, the lifetimes of the observed bands have also been measured. 相似文献
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Combined neural network and reduced FRF techniques for slight damage detection using measured response data 总被引:2,自引:0,他引:2
Summary This paper deals with structural damage detection using measured frequency response functions (FRF) as input data to artificial
neural networks (ANN). A major obstacle, the impracticality of using full-size FRF data with ANNs, was circumvented by applying
a data-reduction technique based on principal component analysis (PCA). The compressed FRFs, represented by their projection
onto the most significant principal components, were used as the ANN input variables instead of the raw FRF data. The output
is a prediction of the actual state of the specimen, i.e. healthy or damaged. A further advantage of this particular approach
is its ability to deal with relatively high measurement noise, which is a common occurrence when dealing with industrial structures.
The methodology was applied to detect three different states of a space antenna: reference, slight mass damage and slight
stiffness damage. About 600 FRF measurements, each with 1024 spectral points, were included in the analysis. Six 2-hidden
layer networks, each with an individually-optimised architecture for a specific FRF reduction level, were used for damage
detection. The results showed that it was possible to distinguish between the three states of the antenna with good accuracy,
subject to using an adequate number of principal components together with a suitable neural network configuration. It was
also found that the quality of the raw FRF data remained a major consideration, though the method was able to filter out some
of the measurement noise. The convergence and detection properties of the networks were improved significantly by removing
those FRFs associated with measurement errors.
Received 9 March 2000; accepted for publication 12 December 2000 相似文献
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Synthesis and Crystal Structure of Mercury(II) Metal Crown Ether with N‐Heterocyclic Carbene Linkage
The mercury(II) metal crown ether ( 2a ) was obtained in high yield by reaction of the carbene precursor 1,2‐bis[N‐(1‐naphthylmethylene)imidazoliumethoxy]benzene dihexafluorophosphate ( 1 ) and Hg(OAc)2. Addition of NaI to the acetone solution of 2a resulted in precipitation of pale yellow solid 2b . The structures of 2a and 2b were determined by single‐crystal X‐ray diffractometry. Both molecules display a helical conformation with a torsional cycle. The mercury atom in complex 2a is tricoordinated by two intramolecular carbene carbon atoms and an acetate oxygen atom. The mercury atom in complex 2b is tetracoordinated by two intramolecular carbene carbon atoms and two cis‐iodine atoms. 相似文献
80.