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41.
电路参数随时间变化的介观LC电路的波函数和压缩效应 总被引:2,自引:0,他引:2
本文通过正则变换,采用路径积分的方法,得出了电路参数随时间变化的介观LC电路的严格波函数,研究了含时相干态下电路中电荷和电流的压缩效应。 相似文献
42.
X.Y. Xu W.J. Liu M.L. Zhong X.L.Li S. Yang R. Z. Ba 《航空制造技术》2004,(Z1):73-78
对激光合成颗粒增强金属间化合物基复合材料进行了研究,包括Ni3Al/WC、NiAl/TiC、Ti3Al/TiC和MoSi2/SiC,用扫描电镜、能谱仪和X射线衍射仪对材料成分和组织特征进行了分析,提出并讨论了影响激光合成金属间化合物基复合材料的关键问题.激光合成具有多种强韧化方法协同、提高金属间化合物强度和塑性的特点,有利于金属间化合物性能的综合改善. 相似文献
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利用外辐射源(如调频广播、电视、GPS等的发射信号)的无源雷达探测技术一直是国内外研究的热点。在目标检测上,直达波信号的干扰不但对通道的动态范围提出了极高的要求,同时对微弱目标回波的检测构成了限制。文中利用二元阵的方法对直达波的干扰进行抑制,并对其对消性能进行了仿真分析和研究。 相似文献
45.
As a promising numerical tool of structural dynamics in mid-and high frequencies, the wave and finite element method (WFEM) is receiving increasingly attention and applications. In this paper, an enhanced WFEM has been developed with a reduced model and a new eigenvalue scheme. The reduced model is applicable for structures with piezoelectric shunts or local dampers;the new eigenvalue scheme can mitigate the ill-conditioning when the wave basis is calculated. The enhanced WFEM is applied to a thin-wall structure with periodically distributed piezoelectric mate-rials (PZT). Both free wave characteristics and forced response are analyzed and the influences of the suggested enhancements are presented. It is shown that if the control factors are properly cho-sen, these enhancements can improve the accuracy while accelerating the calculation. Resulting from the complexity of the application, these enhancements are not optional but imperative. 相似文献
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In this work, an enriched model describing the longitudinal wave propagation is established based on Mindlin’s Second Strain Gradient(SSG) theory, which can describe the heterogeneity caused by the micro-structure interactions in the frame of continuum mechanics. The governing equation and associated boundary conditions are derived based on Hamilton’s principle, then the dispersion relation of non-classical longitudinal wave together with the extra-waves appearing exclusively in SSG theory model... 相似文献
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A. Taori V. Kamalakar A. Jayaraman 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
We summarize two years of Mesosphere Lower Thermosphere Photometer (MLTP) operation of mesospheric OH and O2 emission monitoring. The deduced mesospheric OH and O2 temperatures show large variability. Nightly temperature variations over Gadanki (13.5°N, 79.2°E) are dominated by the short period wave features, while tidal amplitudes are relatively small. Our measurements are the first to report a long period seasonal variation at two upper mesospheric altitudes simultaneously over the Indian sector. Our observations reveal the presence of a dominant semi-annual oscillation (∼6 months periodicity) together with a shorter period (∼2.5 months periodicity) oscillation in both OH and O2 data. 相似文献
50.
Tai-Yin Huang Michael Hickey 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(9):1478-1487
Secular variations of OH airglow (8,3) band and of the intensity-weighted temperature induced by a gravity wave packet at three latitudes in the northern hemisphere in the Mesosphere/Lower Thermosphere region are investigated using a 2-D, time-dependent, fully nonlinear OH chemistry–dynamics model. A net-cycled average survives due to wave transience and dissipation. The integrated OH (8,3) volume emission rates show a 20 percent increase induced by the wave packet. The corresponding intensity-weighted temperature shows an initial increase up to 2 percent then a gradual decrease for the remainder of the simulation time by the same wave packet. These secular variations could be mistaken as long-period or short-period waves in the airglow observations. Therefore, care must be taken when analyzing the data from observations. 相似文献