Modified Reynolds Equation for Squeeze-Film Air Damping of Slotted Plates in MEMS Devices

推导出了一个适用于槽板结构压膜空气阻尼的微分方程.该方程与传统雷诺方程的区别是在雷诺方程的左边增加了一个用以表示气体从槽流出所引起的阻尼效应的修正项,并考虑了槽中有限气流通道长度的端头修正.在适当的边界条件下,利用此方程可以求解槽板压膜阻尼的压强分布、阻尼力和阻尼力系数.该槽板结构压膜空气阻尼的微分方程对槽板的厚度和横向尺度没有限制,为分析有限尺寸和有限厚度槽板的压膜空气阻尼提供了一个有用的方法.     

微电子机械器件压膜空气阻尼的一般化雷诺方程

推导建立了一个用于微电子机械(MEMS)器件压膜空气阻尼的一般化微分方程.该方程很好地解决了分析有限尺寸孔板的边界和孔板的厚度对压膜阻尼的影响的困难.结合边界条件求解该方程可以得到各种压膜阻尼结构中的阻尼压强分布和阻尼力.以长条板为例得到了有限宽度和有限厚度孔板压膜阻尼的压强分布和阻尼力的解析解,在非孔板的条件下该解退化为一般传统雷诺方程的解,而在无限大薄孔板的极端条件下,该解也与传统雷诺方程在此条件下的解相一致,进一步证明了该方程的正确性.因此,该一般化的雷诺方程为MEMS器件的压膜阻尼设计提供了有效的手段.     

微电子机械器件压膜空气阻尼的一般化雷诺方程

推导建立了一个用于微电子机械(MEMS)器件压膜空气阻尼的一般化微分方程.该方程很好地解决了分析有限尺寸孔板的边界和孔板的厚度对压膜阻尼的影响的困难.结合边界条件求解该方程可以得到各种压膜阻尼结构中的阻尼压强分布和阻尼力.以长条板为例得到了有限宽度和有限厚度孔板压膜阻尼的压强分布和阻尼力的解析解,在非孔板的条件下该解退化为一般传统雷诺方程的解,而在无限大薄孔板的极端条件下,该解也与传统雷诺方程在此条件下的解相一致,进一步证明了该方程的正确性.因此,该一般化的雷诺方程为MEMS器件的压膜阻尼设计提供了有效的手段.     

硅微结构加速度传感器空气阻尼的研究

本文从理论上和实验上对硅压阻式加速度传感器的三种结构：悬臂梁、四梁和双岛－五梁的空气阻尼问题进行了研究．在这三种结沟中，四梁结构的质量块具有平行的运动方式，但是悬臂梁和双岛－五梁结构中的质量块既有平动又有转动，对这种非平动状态的空气阻尼的分析尚未见报道．本文从决定平板运动阻尼特性的Ｒｅｙｎｏｌｄｓ方程出发。在平板平动情况解的基础上推导了非个动板的阻尼力以及双面阻尼的阻尼力．用这些结果对三种结构进行了单面和双面阻尼设计，实验结果与理论分析相符．     

抗磁稳定悬浮结构的阻尼特性研究

研究了一种抗磁稳定悬浮结构的涡流阻尼力的阻尼特性。建立了求解涡流阻尼及阻尼系数的数学模型,借助MATLAB和COMSOL 5.6通过三维电磁场有限元仿真分析方法研究了涡流阻尼的特性以及外部激励频率、振幅、悬浮磁体厚度、导体板厚度等对涡流阻尼的影响,给出了其变化规律。结果表明:增大磁体半径与厚度、增大抗磁体边长和厚度以及减小悬浮间隙都可增大涡流阻尼。除此之外,增大外部激励的振幅与频率也可以增大涡流阻尼,但增大激励频率时涡流阻尼会出现相位滞后现象。该结果对于分析研究抗磁悬浮结构的振动特性具有一定的参考意义。     

MEMS陀螺中带孔结构空气阻尼建模分析

针对MEMS陀螺中带孔结构的空气阻尼问题,根据制作的微陀螺,利用MATLAB软件对模态匹配、Q值匹配与灵敏度之间的关系进行了仿真分析。仿真结果表明在驱动和检测模态匹配时灵敏度幅值最大,但工作带宽却随Qx与Qz乘积的增大而减小。建立了空气阻尼计算模型,并利用实验测试数据对空气阻尼计算模型进行了分析和检验。研究发现,微陀螺在驱动方向上,带孔平板结构的滑膜空气阻尼计算模型存在一定误差,经过系数修正后Q值的理论值与测试值具有较好的一致性,但仍需要进一步地修正和完善;在检测方向上,压膜空气阻尼模型比较准确,精度较高能控制在5%以内,可直接用于微陀螺的空气阻尼设计中。     

平面结场板结构表面场分布的二维解析

提出了基于二维泊松方程解的平面结场板结构的二维表面电场解析物理模型.在该模型基础上,分析了衬底掺杂浓度、场板厚度和长度对二维表面场分布的影响.解析预言的场分布与击穿电压的计算结果与先前的数值分析基本符合.该模型为场板结构的优化设计提供了理论基础.     

平面结场板结构表面场分布的二维解析

提出了基于二维泊松方程解的平面结场板结构的二维表面电场解析物理模型 .在该模型基础上 ,分析了衬底掺杂浓度、场板厚度和长度对二维表面场分布的影响 .解析预言的场分布与击穿电压的计算结果与先前的数值分析基本符合 .该模型为场板结构的优化设计提供了理论基础     

结构参数对微穿孔板结构声学特性的影响研究

微穿孔板结构声学特性与结构参数密切相关,该文讨论了这些结构参数对吸声性能的影响.采用传递矩阵法计算微穿孔板结构的声学特性,在验证理论计算结果可靠的基础上,研究结构参数(如穿孔率、微孔直径、板厚和空腔距离)对微穿孔板结构吸声性能的影响规律.结果表明,穿孔直径、板厚和穿孔率主要影响吸声结构的共振吸声峰值,空腔厚度主要影响共振基频;共振吸声峰值随穿孔率、微孔直径和空腔厚度增加而降低,随板厚增加而增大.增加穿孔率,共振基频向低频移动;而增加微孔直径、板厚和空腔厚度,共振基频向高频移动;吸声频带宽度随穿孔率增大而增加,随微孔直径、板厚和空腔厚度增加而变窄.     

有限厚度周期孔径阵列电磁特性的加速分析

将有限厚度周期结构的电磁散射问题分解为外部问题和内部问题,采用混合位积分方程（MPIE）,用Ewald变换对周期格林函数进行加速,提高计算效率;在内部问题的分析中,为简化积分方程,通过零厚度近似,并引入厚度修正项,完成了从有限厚度至零厚度的平滑过渡。与采用传统MOM—IE方法的结果对比,新方法的结果吻合良好,说明了此方法在有限厚度周期结构电磁散射分析中的有效性．     

Slotted waveguide directional coupler characteristics

A moment method (MoM) solution for slotted waveguide directional couplers which is sufficiently accurate for predicting the couplers' characteristics is demonstrated. The slot length in the waveguide directional couplers considered is about four wavelengths and the wall thickness is about 0.27 λ. To simplify the numerical computation, the formulation assumes a uniform field across the slot aperture and utilizes Galerkin's method with the entire domain sinusoidal basis. A self-consistent method taking the finite wall thickness into account avoids an additional matrix equation, as in other MoM formulations. The final solution forms the basis for an efficient computer code applicable to dielectric-loaded slotted waveguide directional couplers. The uniform field assumption restricts the present solution to narrow slots. Numerical results verify, by comparisons with published analytical and experimental data, that this solution is valid for slot lengths as long as 4λ. A detailed discussion of the characteristics of narrow-wall and broad-wall slotted waveguide directional couplers is presented     

Development of the Fel’d’s concepts on the slotted waveguide devices in the works of researchers from the Karazin National University

The development of the Fel??d??s concepts on the slotted waveguide emitters in various slot systems is presented. Various narrow slots (slots with coordinate boundaries and tilted slots whose length is comparable with one half of wavelength, electrically long slots whose length is no less than one hundred wavelengths, slots in waveguides that are uniformly or partially filled with insulator, infinite slots, slots with reflecting walls, and slots that are uniformly or partially filled with insulator) are considered. The analysis of the effect of the waveguide wall thickness, the selection of the approximating function for the electric field in the slot, the correctness of the representation of the tensor Green function, and the application of the potential vector eigen-functions of the Helmholtz equation in the study of the magnetic field in the slot region are discussed.     

The influence of vertical deflection of the supports in modeling squeeze film damping in torsional micromirrors

The objective of this work is to create an analytical framework to study the problem of squeezed film damping in micromirrors considering the bending of the supporting torsion microbeams. Using mathematical and physical justifications, nonlinear Reynolds equation governing the behavior of the squeezed gas underneath the mirror is linearized. The resulting linearized equation is then nondimensionalized and analytically solved for two cases of the infinitesimal and finite tilting angle of the mirror. The obtained pressure distribution from the solution of the Reynolds equation is then utilized for finding the squeezed film damping force and torque applied to the mirror. The results show that in the case of the infinitesimal tilting angle, the squeezed film damping can be modeled with a linear viscous damping in both torsional and lateral directions. It is also shown that when the mirror's rotation angle is small, with increasing the length of the mirror, the damping force and damping torque are increased. For the case of the finite tilting angle it was observed that the applied damping torque highly depends on the tilting angle of the mirror as well as the ratio of its vertical to angular velocity and as a result the effect of the vertical velocity of the mirror on the squeezed film damping force and torque applied to the mirror cannot be simply neglected. It is expected that the qualitative and quantitative knowledge resulting from this effort will ultimately allow the analysis, optimization, and synthesis of micromirrors for improved dynamic performance.     

On the analysis of slotted waveguide arrays

A strategy for the full-wave analysis of slotted waveguide planar arrays is presented and demonstrated. The core of the method is a suitable segmentation of the antenna into two fundamental regions: an "internal" one, formed by the waveguide circuit, and the "external" one, consisting of the half space above the plate where the radiating slots are located. The internal region is further segmented into several blocks, connected to each other via their generalized admittance matrices (GAMs). The latter are calculated by means of either a commercial or a home made tool. The front plate is considered as a whole and analyzed by the moment method, in terms of modes of the slots. The latter are considered as short sections of waveguide whose length is just the conductor thickness, connecting the internal and external regions. The approach has been applied with success to a number of large planar arrays, both in rectangular and ridge waveguide.     

采用两种信道接入机制的认知无线电网络

时隙Aloha和CSMA是有效的随机接入协议,它们能组成更先进的媒体接入协议。研究了采用时隙Aloha和CSMA的认知无线电网络。其中,主用户比次用户有更高的优先权,次用户需检测信道,避免干扰主用户。因此,主用户采用时隙Aloha接入信道,次用户采用CSMA感知时隙Aloha的时隙,在空闲时隙传输数据包。     

Slotted antenna array excited by a coplanar waveguide

The letter gives a new concept of exciting slotted antenna arrays. There both the slots and the feeder are etched on the same side of the printed circuit board. A channel is cut perpendicular to the slots and a coplanar waveguide for exciting the slots is inserted into the channel. The concept has been experimentally verified on a model.