含U型腔MDM波导传感特性研究

为实现结构紧凑且具有较高品质因数的纳米级折射率传感器,文章提出了一种含金属挡板的金属-电介质-金属(MDM)波导与U型谐振腔侧边耦合的等离激元波导结构。利用有限元分析法,定量分析了结构参数和介质折射率对该结构透射谱线及折射率传感品质因数(FOM)的影响。研究结果表明,U型腔中的二阶谐振模式产生谱宽较窄的离散态透射谱,而带有金属挡板的MDM波导形成较宽的连续态透射谱,两者相干叠加激发具有反对称线型法诺(Fano)共振。经过结构参数扫描分析得到优化后的波导结构折射率传感灵敏度可达800 nm/RIU,FOM可达47382。该结构可以为纳米尺度的折射率传感器设计提供有效参考。

基于光纤U形腔的马赫-曾德尔干涉仪的磁场传感器

本文研制了一种光纤磁场传感器,使用涂有磁流体(MF)的全光纤马赫-曾德尔干涉仪(MZI)的U形腔体进行实验验证。光纤磁场传感器是在两段单模光纤(SMF)之间拼接一段单模光纤形成U型光学腔制造而成的,该设计具有光纤几何关系。由于几何对称性MZI对周围折射率(RI)具有很强的敏感性,灵敏度高达−13588 nm/RIU,且磁流体的折射率对磁场敏感,因此所提结构实现了磁场传感功能。实验结果表明,该传感器磁场灵敏度高达137 pm/Oe,磁场范围从0~250 Oe几乎呈线性。本文所设计的光纤磁场传感器具有体积小、成本低、易于制造、坚固耐用、灵敏度高、重复性好、易于与光纤系统集成等相关优势。

声学覆盖层内嵌空腔的一种数值优化方法

给定材料参数的条件下,如何确定最优声腔结构是声学覆盖层设计中的关键问题。针对去耦型声学覆盖层,提出一种轴对称模型与拓扑优化相结合的方法,可以快速寻得最优的声腔结构。文中采用轴对称简化模型来描述周期性覆盖层的声学特性,通过与正方形模型、六边形模型以及实验结果的对比,验证了有限元模型的正确性。采用基于密度的拓扑优化方法,对覆盖层的不同区域进行了优化,以此为基础,获得一种含U型腔的覆盖层结构,在常压和静压下,其隔振性能均优于典型的圆柱空腔覆盖层的隔振性能。

Pressure impact characteristic of vane type continuous rotary motor under different buffer structures

In order to solve the problem of pressure shock on the continuous rotary electro-hydraulic servo motor,the mathematical models of pressure gradient under the structure of pre-compressed chamber and U-shaped groove were established.The optimal structure dimensions of the pre-compressed chamber and the U-shaped groove were determined.The fluid models were established by Solidworks under the four structures of triangular groove,triangular groove with pre-compression chamber,U-shaped groove and U-shaped groove with pre-compression chamber.Simulation analysis of depressurization process of fluid models was performed based on FLUENT.The pressure nephograms of different buffer structures were compared and analyzed,and the pressure change curves and pressure gradient change curves in the process of depressurization were obtained.The results show that the optimal edge length of the pre-compressed chamber of continuous rotary electro-hydraulic servo motor is 20 mm in the process of decompression.The pressure reduction effect is the best when the width of the U-shaped groove is 1.5 mm and the depth is 1.65 mm.The U-shaped groove structure with pre-compression chamber is more conducive to alleviate the pressure shock phenomenon of the motor compared with different combine buffer structures.

新型多频蝶形微带天线

微带天线工作频带较窄,若能同时激励多个谐振点,可以变相拓展带宽,因此设计一种多频蝶形微带天线。3块介质基板构成“U”型半封闭腔体,天线的辐射臂采用1 4周期正弦轮廓结构,在辐射臂上开取3对“工”字型缝隙,同时在馈电端口处加载枝节。实验结果表明,蝶形微带天线在5个雷达波段(S,C,X,Ku,K)各有1个谐振频点,分别为2.6 GHz,6.8 GHz,11.7 GHz,16.5 GHz,18.45 GHz。通过对比分析可知:在不改变天线整体尺寸的情况下,正弦边结构可调节谐振频点位置;加载的矩形枝节有利于改善天线的阻抗匹配度,降低回波损耗;“U”型半封闭腔体可有效提高增益,其中C波段的增益由0.71 dB可提升到4.30 dB。