The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructi...The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.展开更多
石墨烯自被成功制备以来,就以其优异的材料性能在众多领域受到了广泛关注,特别是其具备快速光电响应、宽光谱吸收、尺寸优势等特性,是制备微纳光电探测器的理想材料之一。目前,石墨烯光电探测器已经实现,但基于传统结构的石墨烯探测器...石墨烯自被成功制备以来,就以其优异的材料性能在众多领域受到了广泛关注,特别是其具备快速光电响应、宽光谱吸收、尺寸优势等特性,是制备微纳光电探测器的理想材料之一。目前,石墨烯光电探测器已经实现,但基于传统结构的石墨烯探测器存在光吸收效率低、光电响应差的问题。利用等离激元实现光吸收增强是一种可行的技术路线,但其存在微纳结构过于复杂、成本过高、性能不足等问题。本文提出了一种基于Au光栅/石墨烯/h-BN/SiO_(2)的异质结构,利用h-BN与红外光相互作用产生的声子极化激元效应,将红外光局域在石墨烯中,增强石墨烯与异质结构整体的吸收率;同时,石墨烯与h-BN的晶格常数相近,该异质结构可最大程度地发挥石墨烯优异的光电性能。通过有限元(Finite element method,FEM)方法对吸收率和电磁场分布进行分析,发现在入射光频率为1550 cm^(-1)时,Au光栅/石墨烯/h-BN/SiO_(2)混合结构石墨烯层的功率耗散密度是Au光栅/石墨烯/SiO_(2)对照组结构的4.4倍,光吸收率是对照组的6.5倍。同时,通过控制h-BN的厚度、Au电极的厚度及栅宽可以实现对吸收强度的调控。该研究为实现基于石墨烯的中红外光电探测器提供了理论依据。展开更多
基金Project(51978585)supported by the National Natural Science Foundation,ChinaProject(2022YFB2603404)supported by the National Key Research and Development Program,China+1 种基金Project(U1734207)supported by the High-speed Rail Joint Fund Key Projects of Basic Research,ChinaProject(2023NSFSC1975)supported by the Sichuan Nature and Science Foundation Innovation Research Group Project,China。
文摘The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.
文摘石墨烯自被成功制备以来,就以其优异的材料性能在众多领域受到了广泛关注,特别是其具备快速光电响应、宽光谱吸收、尺寸优势等特性,是制备微纳光电探测器的理想材料之一。目前,石墨烯光电探测器已经实现,但基于传统结构的石墨烯探测器存在光吸收效率低、光电响应差的问题。利用等离激元实现光吸收增强是一种可行的技术路线,但其存在微纳结构过于复杂、成本过高、性能不足等问题。本文提出了一种基于Au光栅/石墨烯/h-BN/SiO_(2)的异质结构,利用h-BN与红外光相互作用产生的声子极化激元效应,将红外光局域在石墨烯中,增强石墨烯与异质结构整体的吸收率;同时,石墨烯与h-BN的晶格常数相近,该异质结构可最大程度地发挥石墨烯优异的光电性能。通过有限元(Finite element method,FEM)方法对吸收率和电磁场分布进行分析,发现在入射光频率为1550 cm^(-1)时,Au光栅/石墨烯/h-BN/SiO_(2)混合结构石墨烯层的功率耗散密度是Au光栅/石墨烯/SiO_(2)对照组结构的4.4倍,光吸收率是对照组的6.5倍。同时,通过控制h-BN的厚度、Au电极的厚度及栅宽可以实现对吸收强度的调控。该研究为实现基于石墨烯的中红外光电探测器提供了理论依据。
