基于拓扑优化的微带天线奇异方向图设计

拓扑优化方法避免了结构的参数化扫描,直接优化材料排布,用于无源微波器件设计,可极大程度拓展设计解域。文中基于拓扑优化方法研究了微带天线的奇异辐射方向图设计。首先分析了具有奇异辐射方向图的伴随敏感度,其次构建了基于过渡边界条件的二维金属优化模型,再次提出了针对奇异辐射的多种目标场函数,分别实现了高增益定向指向波束、等幅双波束和任意方向线极化波束等奇异方向图。为验证算法有效性和准确性,最后加工并测试了具有高增益指向偏转方向图的微带天线,测试结果与拓扑优化结果吻合较好。此方法特别适合具有复杂目标的无源电磁器件设计。     

频变耦合双工器的快速综合方法

为了解决频变耦合双工器的快速综合问题，提出了一种耦合矩阵优化综合方法.该方法分通道滤波器综合和优化两个阶段.首先应用推导的双工器特征多项式迭代求解出各通道滤波器的特征多项式，并应用耦合矩阵综合法计算出各通道滤波器的规范耦合矩阵.然后，根据指定的频变耦合拓扑结构，优化逼近规范耦合矩阵.最后，反归一化双工器的频变耦合矩阵得到最终设计参数.电路仿真结果与理论综合结果一致，表明了所提方法的正确性和有效性.该频变耦合双工器快速综合方法保持了较好的通带等波纹特性，且可以根据设计需要，任意指定各通道滤波器的频变耦合拓扑结构.     

基于拓扑优化的4 m 望远镜底座结构设计

为满足4 m望远镜底座结构高刚度和轻量化的需求,研究了考虑结构变形和模态约束下的拓扑优化问题。首先,基于连续体结构拓扑优化的思想,以单元虚拟密度为设计变量,以位移变形和一阶频率及质量为优化约束,应变能最小为优化目标,建立了底座设计的拓扑优化数学模型,并详细推导目标函数及约束条件的灵敏度;然后,对底座结构应用拓扑优化设计,并以所得的理想概念构型为基础,进行底座结构的详细设计;最后,采用有限元法对优化模型进行静刚度和动刚度的分析与校核。设计结果表明,底座质量从27.66 t减至22.15 t;最大变形量由0.0377 mm减小为0.014 mm;一阶频率从217.1 Hz提高至247.45 Hz;在减小质量的同时,有效提高了底座结构的静刚度和动刚度,验证了拓扑优化方法的有效性。该方法将对4 m望远镜跟踪架的其他部件设计提供帮助。     

Design evolution and synthesis of multi-domain engineering systems using artificial immune system

A multidisciplinary design method is developed in this paper to optimally evolve and synthesize multi-domain engineering systems. The design methodology utilizes two navigated optimization loops to handle the optimization of both topology and parameters. In the topology optimization, which is the outer loop, the proposed artificial immune system (AIS) tool, which contains a clonal selection algorithm (CLONALG) and negative selection techniques, is utilized to synthesize the number and the structure of the elements. A novel concept of “artificial vaccination” is developed, which is responsible for the incorporation of domain knowledge. In the inner loop, an optimization tool that incorporates simple AIS is utilized for parameter tuning in any generated topology. By acquiring knowledge and learning from prior trials, the evolution parameters are automatically and intelligently tuned to make the design model more reliable and to facilitate more effective navigation. Numerical study on the design of a hydraulic engine mount is presented. The results indicate that the proposed design flowchart enables the designers to successfully modify (specifically, extend or reduce) the initial colony in order to obtain the optimal solution.     

大口径反射镜水平集拓扑优化设计

为了设计适用于空间望远镜的具有质量轻、刚度高、高面形精度特点的大尺寸反射镜,提出了基于水平集方法的反射镜拓扑优化设计方法。首先,在口径1 m反射镜镜体初始结构模型的基础上建立有限元模型,基于SIGFIT采用DRESP2建立面形RMS的目标响应函数,将镜面面形精度直接作为目标函数,在重量约束条件下,基于变密度算法与水平集拓扑方法分别进行优化设计,并基于OSSmooth功能对设计结果分离阈值进行研究。通过对优化模型分离阈值进行分析,得到最优化的输出结构模型。采用水平集方法的拓扑优化设计方法的中间密度单元格数目远小于变密度方法,输出结构边界连接性更好。优化模型面形RMS值小于/50（=632.8 nm）,满足设计指标。     

拓扑优化方法的研究现状及在微机构设计中的应用

简要介绍了MEMS的设计现状和拓扑优化方法 ,并根据MEMS中微机构的特点 ,概述了拓扑优化方法在微机构中的应用。最后以微夹钳为例 ,对不同负载、不同约束情况下微夹钳结构进行了拓扑优化设计     

红外光电系统机械固定件的拓扑优化设计

红外光电系统机械件复杂度高,在满足稳定性要求的前提下,对结构的轻量化有着更急迫的需求。本文采用ANSYS拓扑优化方法对某红外光电系统进行拓扑优化设计,并以电源固定件为例,以结构柔度最小为设计目标,单元密度为设计变量,实现30%的体积约束,并对拓扑优化的结果进行模型重构。与初始经验设计方案对比,优化重构后的固定件减重37.8%,且结构的刚度和强度均得到了提升。进而表明,拓扑优化方法可以为红外光电系统结构的轻量化设计提供有利的借鉴。     

基于有限元法和色散COM模型的声表面波滤波器联合仿真

针对任意复杂膜系结构和电路拓扑结构的声表面波(SAW)滤波器的精确快速设计问题,该文基于声/电/磁多物理场耦合全波仿真平台,结合基因遗传优化算法和通用图形处理器(GPGPU)加速技术,利用有限元分层级联精确模型(HCT)优化设计梯形谐振器,色散COM模型优化设计纵向耦合谐振器,实现了任意复杂膜系结构和电路拓扑结构的SAW滤波器的正向设计与优化。通过42°Y-XLiTaO₃常规SAW滤波器的优化设计与研制,设计优化结果与实验结果吻合较好,验证了该方法的有效性和可行性。     

红外导引头稳定平台主框架拓朴优化设计

为了提高红外导引头稳定平台动态性能,减小振动环境对其稳定精度和光电载荷成像质量的影响,采用基于变密度法的拓扑优化理论,利用NX/TOSCA软件,以刚度最大化为目标函数,以体积比约束为设计响应约束,对红外导引头稳定平台主框架进行了拓扑优化设计。对比分析了经优化设计和经验设计的主框架结构形式的刚度及模态振型。结果显示,经拓扑优化的主框架在动态性能有所提高的情况下,结构质量大幅地减小,最大变形量由3.2m减小到2.8m,一阶固有频率由1567 Hz提高到1953 Hz,质量减小32.4%,有利于导引头轻量化水平的提升和整机性能的提高。最后,通过振动试验和稳定精度的检测数据验证了主框架的动态性能,说明了拓扑优化结果的正确性,这种拓扑优化方法可为其他重要件结构设计提供帮助。     

Design of a frequency selective structure with inhomogeneous substrates as a thermophotovoltaic filter

In this paper, the design of a thermophotovoltaic (TPV) filter with high-pass characteristics is presented. The filter is in the form of a frequency selective structure (FSS) with cascaded inhomogeneous dielectric substrates. The goal is to allow for more design flexibility using dielectric periodic structures to deliver a sharper filter response. Therefore, the primary focus is to design a periodic material substrate composition (supporting FSS elements) using a topology optimization technique known as the density method. The design problem is formulated as a general nonlinear optimization problem and sequential linear programming is used to solve the optimization problem with the sensitivity analysis based on the adjoint variable method for complex variables. A key aspect of the proposed design method is the integration of optimization tools with a fast simulator based on the finite element-boundary integral method. The capability of the design method is demonstrated by designing the material distribution for a TPV filter subject to pre-specified bandwidth and compactness criteria.     

A new 2-D image reconstruction algorithm based on FDTD and design sensitivity analysis

This paper proposes a numerical algorithm that reconstructs the complex permittivity profile of unknown scatterers by the design sensitivity analysis (DSA) and topology optimization technique. By introducing the DSA and adjoint-variable method, the derivatives of the error function with respect to the complex permittivity variables can be calculated, and the material property in each cell can be changed simultaneously using sensitivity information. The steepest descent method is used as an optimization technique. The proposed method is validated by applying it to reconstructions of unknown two-dimensional scatterers that are illuminated by TM/sup z/ with a Gaussian-pulsed plane wave.     

二氧化碳探测仪镜筒结构的多目标优化设计(英文)

为满足镜筒结构高强度、轻量化及良好的热环境适应性的要求,研究了多工况下同时考虑结构刚度和一阶固有频率的多目标优化问题。首先,基于变密度连续体结构拓扑优化方法,采用加权和法和靶向量法定义了多工况下多目标优化函数;然后进行了镜筒的优化设计。整个优化设计包括拓扑优化和厚度优化两部分。在拓扑优化中,以刚度和频率最大为目标函数,得到了满足要求的镜筒结构材料的最佳分布,并以此为依据,完成了镜筒结构的三维建模;以拓扑优化所得结构的柔度值和一阶频率为约束,质量最小为目标函数,对镜筒结构各厚度进行了优化。优化设计结果表明,镜筒质量由18.63 kg减少至12.46 kg;重力作用下最大变形由0.013 mm减少至0.001 9 mm;热载荷作用下最大变形由0.098 mm减少至0.062 mm;一阶固有频率从65.6 Hz提高至189.83 Hz。该优化设计方法有效缩短了设计周期,提高了镜筒结构的性能,满足了系统设计要求。     

大口径望远镜次镜系统的拓扑优化设计

针对地基大口径望远镜次镜系统加工精度和装调精度的要求，提出了基于拓扑优化的次镜系统结构设计方法。该方法利用变密度的拓扑优化思想，将次镜系统的Spider结构和Serrurier桁架的设计域限定为基结构，以期望方向的变形最小，通过材料的去留决定结构的最终形状和尺寸。首先，以相对密度为设计变量，Spider结构以1阶振型和重力方向变形为设计约束，桁架以X向和Y向变形为设计约束，建立各结构的拓扑优化模型；然后，以拓扑优化所得构型为基础，利用Workbench进行优化迭代；最后，设置优化参数，采用有限元法进行动静刚度分析和优化。结果显示4 m望远镜次镜系统的1阶谐振为22.7 Hz，光轴指向天顶和水平时重力方向偏移分别为-0.173 mm和-0.195 mm，并且Spider结构和Serrurier桁架的轻量化率超过30%。该结果验证了文中方法的有效性。     

基于负载均衡和流量优先级的网络拓扑设计

交换式以太网网络的拓扑结构设计是一个带约束的优化问题,需要同时考虑多种约束条件。本文中定义了两个主要的准则：交换机负载均衡和流量最短路径。根据设计目标而衡量每条准则的权重．对拓扑进行评分而进行网络的拓扑结构设计。该方法以终端节点间网络流量需求矩阵和终端设备间流量优先级矩阵为输入,利用遗传算法从所有的拓扑结构中找出最优拓扑,决定交换机生成树拓扑和终端节点的分布位置。通过网络仿真,可以证明此方法的有效性。     

Analog circuit design optimization based on symbolic simulation andsimulated annealing

A methodology for the automatic design optimization of analog integrated circuits is presented. A non-fixed-topology approach is realized by combining the optimization program OPTIMAN with the symbolic simulator ISAAC. After selecting a circuit topology, the user invokes ISAAC to model the circuit. ISAAC generates both exact and simplified analytic expressions, describing the circuit's behavior. The model is then passed to the design optimization program OPTIMAN. This program is based on a generalized formulation of the analog design problem. For the selected topology, the independent design variables are automatically extracted and OPTIMAN sizes all elements to satisfy the performance constraints, thereby optimizing a user-defined design objective. The global optimization method used on the analytic circuit models is simulated annealing. Practical examples show that OPTIMAN quickly designs analog circuits, closely meeting the specifications, and that it is a flexible and reliable design and exploration tool     

星敏感器支撑结构多目标拓扑优化设计与试验

针对微小卫星对星敏感器的特殊要求,结合星敏感器特殊的工作性能和环境,采用拓扑方法对星敏感器支撑结构进行多目标优化设计并进行有限元分析和试验。首先,对模态分析和随机振动响应的基本理论进行介绍,推导出多目标拓扑优化的表达公式;其次,以支撑结构的体积最小和星敏感器在支撑结构上的四个安装点RMS值最小为目标,以最低自振频率为约束,建立支撑结构的拓扑优化模型,利用OptiStruct软件对其进行拓扑优化设计;然后利用MSC.PatranNastran有限元分析软件对优化后的支撑结构进行模态分析和随机振动响应分析,得到基频为327 Hz ,安装点RMS值的放大率最大为1.55;最后,对支撑结构进行振动试验,试验结果和有限元分析结果的相对误差最大为6.68%,二者吻合较好,该星敏感器支撑结构满足微小卫星对其性能指标的要求。     

Topology Optimization‐Based Inverse Design of Plasmonic Nanodimer with Maximum Near‐Field Enhancement

The near‐field enhancement factor is one of the most significant parameters to evaluate the performance of plasmonic nanostructures. Numerous efforts have been made to maximize the enhancement factor through optimizing the size, shape, and spatial arrangement of metallic nanostructures with simple geometries, such as disk, triangle, and rod. This work implements topology optimization to inversely design a metallic nanoparticle dimer with the goal of optimizing the near‐field enhancement factor in its sub‐10 nm gap. By optimizing the material layout within a given design space, the topology optimization algorithm results in a plasmonic nanodimer of two heart‐shaped particles having both convex and concave features. Full‐wave electromagnetic analysis reveals that the largest near‐field enhancement in the heart‐shaped nanoparticle dimer is originated from the greatest concentration of surface charges at the nano‐heart apex. Inversely designed heart‐, bowtie‐, and disk‐shaped nanodimers are fabricated by using focused helium ion beam milling with a “sketch and peel” strategy, and their near‐field enhancement performances are characterized with nonlinear optical spectroscopies at the single‐particle level. Indeed, the heart‐shaped nanodimer exhibits much stronger signal intensities than the other two structures. The present work corroborates the validity and effectiveness of topology optimization‐based inverse design in achieving desired plasmonic functionalities.     

基于抗毁性和最小费用的网络优化设计方法

针对通信网网络优化设计提出了一种在网络抗毁性指标和网络最小费用之间进行均衡、折衷的优化设计方法。分析了通信网络的特点和设计要素,在此基础上提出了将通信网络进行模型化的方法,根据模型化后的图求出最小费用的连通网络结构,在尽量减少费用的前提下进行抗毁设计的修改。通信网络优化设计的最终设计目标是具有一定抗毁性指标且费用最少的网络拓扑结构。     

高体份SiC/Al复合材料空间相机框架的拓扑优化设计

为了提高空间相机在力/热双重环境条件下的系统稳定性,同时能够实现系统的轻量化目标,在某型空间相机的研制过程中选用了具有高比刚度和热稳定性的高体份SiC/Al复合材料。采用整体式框架结构,将基于变密度法的连续体结构拓扑优化方法应用到相机框架结构的初始设计中,通过设定相应的约束条件和目标函数,进行迭代求解,得到了相机框架分别在X、Y、Z三个方向重力作用下的结构拓扑优化结果,结合工艺要求,最终确定了空间相机框架的设计方案。通过与对比方案比较发现,经过拓扑优化所得到的框架结构在结构刚度及轻量化率上都有明显提高,实现了空间相机框架高刚度、轻量化的设计目标。     

Integrated model parameter extraction using large-scaleoptimization concepts

A robust approach to modelling parameter extraction in microwave circuit design is presented. The approach not only attempts to match DC and AC measurements under different bias conditions simultaneously, but also employs the DC characteristics of the device as constraints on Bias-dependent parameters, this improving the uniqueness and reliability of the solution. The approach is an expansion of the hierarchical modeling techniques recently proposed J.W. Bandler and S.H. Chen (1988). Based on J.W. Bandler and Q.J. Zhang's (1987) automatic decomposition concepts for large-scale optimization, a sequential model building method is proposed which can be combined with powerful l₁ optimization techniques to establish a model with simple topology and sufficient accuracy. Practical FET models are used to illustrate the formulation. A detailed numerical example is presented to show the effectiveness of the approach