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一种高阶精度人工边界条件:出平面外域波动问题 被引量:13
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作者 赵密 杜修力 刘晶波 《工程力学》 EI CSCD 北大核心 2012年第4期7-14,共8页
针对无限外域中的出平面波动问题,提出一种用于近场波动有限元分析的高阶精度人工边界条件。首先,采用变量分离法求解远场初边值问题,建立了时空全局的精确动力刚度人工边界条件;然后,发展了一种由有理函数近似和辅助变量实现构成的时... 针对无限外域中的出平面波动问题,提出一种用于近场波动有限元分析的高阶精度人工边界条件。首先,采用变量分离法求解远场初边值问题,建立了时空全局的精确动力刚度人工边界条件;然后,发展了一种由有理函数近似和辅助变量实现构成的时间局部化方法,并将其应用于动力刚度人工边界条件,得到时间局部的高阶精度人工边界条件;最后,沿人工边界离散高阶精度人工边界条件,并将其与近场集中质量有限元方程耦合,形成对称的时间二阶常微分方程组,采用一种新的显式时间积分方法进行求解。数值算例表明:提出的高阶精度人工边界条件精确、高效、稳定并且容易在现有的有限元代码中实现。 展开更多
关键词 近场波动问题 显式有限元法 人工边界条件 出平面波动 无限外域
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Tunable nonlinear optical responses based on host-guest MOF hybrid materials 被引量:2
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作者 Hongjun Li Lin Zhang +3 位作者 Huajun He Yu Yang Yuanjing Cui Guodong Qian 《Science China Materials》 SCIE EI CSCD 2021年第3期698-705,共8页
The realization of tunable nonlinear optical(NLO)responses in a single nano-/micro-structure is extremely important.However,in lack of effective ways to integrate multiple performances,it still faces severe limitation... The realization of tunable nonlinear optical(NLO)responses in a single nano-/micro-structure is extremely important.However,in lack of effective ways to integrate multiple performances,it still faces severe limitations during applications.Herein,we demonstrate a wavelength-dependent NLO micro-structure based on host-guest metal-organic framework(MOF)materials through encapsulating linear dye molecules into periodic one-dimensional(1D)channels.The confinement to non-centrosymmetric polar dye molecules enhances the second-/third-order NLO responses of the hybrid crystals,causing obvious two-photon luminescence(TPL),second harmonic generation(SHG)and third harmonic generation(THG)responses in the as-prepared composites.The highly ordered structures of MOFs impart spatial regulation on the linear dye molecules to realize orientation alignment,resulting in the polarized anisotropy emission.NIR-to-NIR(NIR,near-infrared region)two-photon pumped lasing is realized with the natural whispering gallery mode resonance cavities of MOFs under the excitation of a 1200-nm fs laser.Furthermore,tunable NLO properties such as TPL,SHG and THG are achieved through switching the incident excitation wavelength from 800 to 1500 nm.Such hybrid materials with tunable NLO responses may open a new avenue toward designing multifunctional NLO devices in the future. 展开更多
关键词 nonlinear optical response metal-organic frameworks second harmonic generation two-photon luminescence
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