LED汽车前照灯散热结构设计与分析

针对LED汽车前照灯的散热问题,对比设计两款有/无散热槽的新型散热器结构形式,利用有限元分析软件ANSYS进行散热结构的热力学分析。针对初始设计的散热结构形式采用控制变量法进行参数优化,最后得出无槽结构的LED灯具最高温度为65.352℃,热应力为235.56 MPa;同等条件下有槽结构的LED灯具最高温度为62.712℃,最大应力为218.7 MPa。计算可知,具有散热槽LED灯具散热器优化后的温度相对无散热槽LED灯具散热器优化后的温度降低2.64℃,最大应力减小16.86 MPa。该仿真结果表明具有散热槽结构的散热器能够提高LED汽车前照灯的散热效果。     

大口径透镜混合柔性支撑结构优化设计

针对大口径透镜,提出了一种新型混合柔性支撑结构,能够使透镜同时满足面形精度及位置精度要求。首先利用卡氏第二定理对各柔性铰链进行分析,建立支撑组件整体柔度模型。然后以柔性支撑组件的总变形能为目标函数,以位置精度及实际使用空间要求为约束,建立结构优化设计模型。之后确定径向柔性支撑结构对组件整体柔度的敏感度最大并对其刚度进行验证。最后对优化后的透镜组件整体结构进行有限元分析,同时利用曲面拟合方法计算镜面面形精度。仿真结果表明,在该新型混合柔性支撑结构的作用下,透镜在各要求工况下的面形精度均优于λ/20 (λ=632.8 nm)。所设计的新型混合柔性支撑结构及其理论分析过程可为高精度大口径透镜的支撑技术提供参考。     

一种新型结构微波介质滤波器的设计及仿真

详细论述了一种新型结构微波介质滤波器的设计方法,分析了滤波器结构中耦合结构与谐振结构的相互影响关系,根据微波网络理论计算出的微波介质滤波器结构参数值,并采用高频结构模拟软件(HFSS)对滤波器结构进行仿真优化,得到了性能满足要求的仿真结果,根据仿真优化的结果制备出的微波介质滤波器其性能与设计要求相吻合。     

MEMS仿生矢量水听器封装结构的隔振研究

利用隔振原理,设计了矢量水声传感器系统中一种新型隔振封装结构模型,即加入橡胶减振器的新型封装结构。采用ANSYS软件对封装模型进行模态分析,研究模型结构和几何尺寸对其隔振性能的影响,确定最优隔振封装结构;对模型的几何尺寸及橡胶隔震材料力学参数进行优化,并对优化模型的隔振性能进行实验测试和评估。实验结果表明：所设计的新型橡胶减振结构具有一定的减振效果,隔离了一定程度的核心器件以外的外界振动干扰,提高了原有封装结构矢量水听器的探测灵敏度。再次验证了硅微MEMS仿生矢量水声传感器不但体积小、质量轻、结构简单,而且具有低频灵敏度高等优点。     

基于OptiStruct的床身结构尺寸优化策略研究

针对传统设计方法设计的床身结构笨重的问题,以某型数控外圆磨床床身为例,在轻量化设计过程中提出一种尺寸优化策略,运用OptiStruct软件对床身结构的垫铁位置进行优化设计,在基于灵敏度分析对床身结构进行尺寸优化设计。优化结果表明,优化后床身的第一阶固有频率提高5.74%,重量减轻7.15%,验证了该尺寸优化策略在床身结构轻量化设计中的可行性及有效性。     

运动训练中人体踝关节安全角度优化控制系统

为解决传统踝关节安全角度控制系统存在PWM控制单元稳定性较差、踝关节角度控制精确度较低等问题,设计了人体踝关节安全角度优化控制系统。通过判断踝关节在运动过程中生理特征的变化情况,完成人体踝关节安全角度的确定。通过电源模块设计、传感器模块设计、串口通信模块设计,完成新型优化控制系统的硬件部分设计。通过主程序设计、功能函数设计、PWM控制单元的加固设计,完成新型优化控制系统的软件部分设计。模拟系统运行环境,设计对比实验结果表明,优化后系统与传统系统相比,PWM控制单元的稳定性、踝关节角度控制精确度均得到大幅提升。     

空间光学遥感器长圆形反射镜组件优化设计与分析

为了减轻空间光学遥感器反射镜的镜体质量,并降低反射镜在恶劣空间环境下的面形误差,利用有限元技术对某长圆形反射镜组件进行了优化设计。首先在反射镜进行轻量化后,对其进行支撑点位置优化和结构拓扑优化;其次对柔性支撑进行优化设计,引入了一种新型柔性铰链,解决了因背板热变形导致反射镜径向变形的问题,改善了反射镜面形精度。优化后的反射镜面形RMS 最大值为14.6 nm,小于/30（=632.8 nm）,一阶固有频率大于100 Hz,满足了设计要求,证明了该优化设计方法合理可行。     

大功率变流器系统H桥低感叠层母线排设计

针对80kVA/400A变流器H桥母线排的设计要求,使用ANSOFT MAXWELL有限元分析软件比较了不同设计原则下杂散电感参数的变化,并提出了一种新型的优化母线排结构,较少了IGBT模块的关断过冲电压,并优化了高频电流的分布。通过仿真和实验分别证实了新型母线排的良好测试结果,最后给出了系统结构和实验波形。     

大功率变流器系统H桥低感叠层母线排设计

针对80KVA/400A变流器H桥母线排的设计要求,使用ANSOFTMAXWELL有限元分析软件比较了不同设计原则下杂散电感参数的变化,并提出了一种新型的优化母线排结构,较少了IGBT模块的关断过冲电压,并优化了高频电流的分布。通过仿真和实验分别证实了新型母线排的良好测试结果,最后给出了系统结构和实验波形。     

空间稳像系统摆镜的一种新型拓扑优化方法

针对于空间稳像系统摆镜的面型精度保持问题,实现摆镜的轻量化设计,在直径110 mm圆平面反射镜的设计过程中将机械结构拓扑优化引入到光学器件设计领域。对背部减重部分进行了拓扑优化设计。对拓扑优化设计的原理和方法做了较为详细的介绍。吸收了变密度法中的SIMP(Solid Isotropic Material with Penalization)插值算法和RAMP(Rational Approximation of Material Properties)插值算法的思想,提出了一种新型惩罚中心可调节的ASMP(Adjusted Solid Material with Penalization)插值算法,并对各种插值算法进行了仿真。仿真结果证明,基于本文提出的新型ASMP插值算法的拓扑优化结果正确可靠,有一定的优越性。同时使用新型方法对摆镜进行了优化,并与其他设计结果进行了比对,结果显示新型拓扑优化结果能够较大程度地提高面型精度,使用起来更加灵活方便。新型差值算法的提出是对现有拓扑优化的插值算法进行了补充完善,也为后续参数优化设计奠定了基础。     

一种新型一维微带PBG单元结构

通过对传统二维微带 PBG 结构的研究,针对微带线的传播常数是微带线相对于接地板上周期孔眼的两个主轴的位置和方向的敏感参数而不能根据实际情况任意布线的缺点,提出了一种新型一维微带 PBG(photonic bandgap)单元结构及其等效 L-C 电路模型。本文提出的 PBG 传输线可以应用于微波集成电路中,能够减小电路尺寸,且可以抑制高次谐波的产生。     

Novel Microstrip Photonic Bandgap Cell Structures

In general, a planar microstrip photonic bandgap (PBG) structure os a periodic array of holes etched in the ground plane of a microstrip line. To use a circuit with a PBG, the PBG structure cannot be fixed on a metal base and needs to be shielded. In this paper, two kinds of novel microstrip PBG unit cells with special patterns etched in the strip line, which can be used as the conventional microstrip circuits, are proposed and analyzed in detail. The results show that the transmission line theory is valid for the theoretic analysis of PBG circuits.     

共面紧凑型微波光子晶体在共面波导中的应用

提出一种地平面刻蚀共面紧凑型微波光子晶体(PBG)的共面波导结构,介绍了微波光子晶体的基本单元结构,并设计出具有90°弯折的共面波导样品.使用矢量网络分析仪测试该结构的散射参数,测量结果显示,其传输特性比普通的共面波导在高频部分具有较大的提高.同时,相比于传统的三维微波光子晶体,该结构具有导体损耗小,加工工艺简单,便于应用于光电封装和单片微波集成电路的特点.

Abstract：

A novel coplanar waveguide using coplanar compact microwave photonic-handgap (PBG) structure is proposed. The basic unit of microwave PBG structure is introduced and a waveguide sample with a 90 degree break is designed. Testing results obtained through vector network analyzer display an obvious promotion in transmission parameter, especially in the high frequency part. Meanwhile, compared with the common 3-dimension microwave PBG structure, this structure with a low conductor loss can be processed with standard planar fabrication technology, which makes it applicable in opto-electronic package and monolithic microwave integrated circuit (MMIC).     

一种新颖的PBG宽阻带低通滤波器

 本文首次提出综合PBG结构和微带线结构两因素,来设计滤波器的概念.与普通PBG结构滤波器不同的是,本文采用具有T形和十字形短截线的微带线代替直线微带线,在接地板上只需刻蚀一列PBG结构即可构成宽阻带低通滤波器.文中以T形短截线PBG结构的低通滤波器为例,运用时域有限差分法(FDTD),分析了在不同短截线长度和PBG结构方孔边长的情况下,该滤波器的传输特性.文中还给出了该滤波器和Rumsey方法与Kim方法设计的级联、并联两种PBG结构低通滤波器的传输特性的模拟结果及其对比分析.最后,文中给出了模拟结果和测试结果,来验证所设计的低通滤波器的有效性.     

A novel TEM waveguide using uniplanar compact photonic-bandgap(UC-PBG) structure

A novel waveguide using a photonic bandgap (PBG) structure is presented. The PBG structure is a two-dimensional square lattice with each cell consisting of metal pads and four connecting lines, which are etched on a conductor-backed Duroid substrate. This uniplanar compact PBG structure realizes a magnetic surface in the stopband and is used in the waveguide walls to provide magnetic boundary conditions. A relatively uniform field distribution along the cross section has been measured at frequencies from 9.4 to 10.4 GHz. Phase velocities close to the speed of light have also been observed in the stopband, indicating that TEM mode has been established. A recently developed quasi-Yagi antenna has been employed as a broad-band and efficient waveguide transition. Meanwhile, full-wave simulations using the finite-difference time-domain method provide accurate predictions for the characteristics of both the perfect magnetic conductor impedance surface and the waveguide structure. This novel waveguide structure should find a wide range of applications in different areas, including quasi-optical power combining and the electromagnetic compatibility testing     

Periodic bandgap and effective dielectric materials in electromagnetics: characterization and applications in nanocavities and waveguides

The main objectives of this paper are to characterize and develop insight into the performance of photonic bandgap (PBG) periodic dielectric materials and to integrate the results into some novel applications. A powerful computational engine utilizing the finite-difference time-domain technique with periodic boundary conditions/perfectly matched layers integrated with Prony's method is applied to provide an in-depth look at the physics of PBG/periodic bandgap structures. Next, the results are incorporated into two classes of applications in the areas of nanocavity lasers and guidance of electromagnetic (EM) waves in sharp bends. A two-dimensional PBG structure with finite thickness is presented to strongly localize the EM waves in three directions and design a high-Q nanocavity laser. It is shown that the periodic PBG/total internal reflections remarkably trap the EM waves inside the defect region. The effect of the number of periodic cells and defect's dielectric constant on the Q of structure is investigated. It has been found that a seven-layer PBG with a dielectric impurity defect can be used in the design of a laser with a Q as high as 1050. Additionally, potential applications of the PBG structures for guiding the EM waves in sharp bends, namely, 90/spl deg/ and 60/spl deg/ channels are demonstrated. It is shown that shaping the bend by introducing small holes can noticeably improve the guidance of the waves at the bends and channel the EM waves with great efficiency. A comparative study between PBG and effective dielectric materials in controlling the EM waves is also provided and it is observed that the novel characteristics of the PBG cannot be modeled using the effective material for the frequencies within the bandgap.     

A uniplanar compact photonic-bandgap (UC-PBG) structure and itsapplications for microwave circuit

This paper presents a novel photonic bandgap (PBG) structure for microwave integrated circuits. This new PBG structure is a two-dimensional square lattice with each element consisting of a metal pad and four connecting branches. Experimental results of a microstrip on a substrate with the PEG ground plane displays a broad stopband, as predicted by finite-difference time-domain simulations. Due to the slow-wave effect generated by this unique structure, the period of the PBG lattice is only 0.1λ₀ at the cutoff frequency, resulting in the most compact PEG lattice ever achieved. In the passband, the measured slow-wave factor (β/k₀) is 1.2-2.4 times higher and insertion loss is at the same level compared to a conventional 50-Ω line. This uniplanar compact PBG (UC-PBG) structure can be built using standard planar fabrication techniques without any modification. Several application examples have also been demonstrated, including a nonleaky conductor-backed coplanar waveguide and a compact spurious-free bandpass filter. This UC-PBG structure should find wide applications for high-performance and compact circuit components in microwave and millimeter-wave integrated circuits     

一种新型微带光子带隙结构

提出一种新型微带光子带隙结构.该结构直接在微带信号线上刻蚀周期性结构,解决了该结构的封装问题,且不增加微带结构的尺寸.采用时域有限差分法分析该结构的S参数,并研究了几何参数与S参数之间的关系,得出了禁带中心频率、带宽随几何参数变化的趋势.     

一种新颖的光子带隙平面螺旋天线

介绍了阿基米德螺旋天线的原理与设计方法,仿真了背腔式阿基米德螺旋天线,并与实际测试结果吻合;研究了一种新颖的光子带隙平面螺旋天线,这种天线用光子带隙代替金属反射腔作为反射面以得到单向波束,仿真与实验发现,光子带隙阿基米德螺旋天线的增益提高约有2dB,后瓣降低了10dB,在有效的工作带宽内天线的性能得到了改善.     

一种基于光子带隙结构的宽阻带低通滤波器

提出了两种新颖的基于光子带隙结构微带线的宽阻带低通滤波器,该滤波器分别采用了T形和十字形短截线来构造．文中还讨论了该滤波器的传输特性,该滤波器设计和制作简易．最后绐出的该低通滤波器的模拟结果和测试结果,表明了该滤波器设计的有效性．