一种图形图象混合的数据表示方法

工程图样的扫描处理方法是当今ＣＡＤ／ＣＧ中的一个迫切需要解决的问题。本文提出了一种适用于整体识别方法的数据结构，在对工程图样进行矢量转换的过程中，统一保存图形和图象的数据，从而在对图段进行跟踪时，能够保证获取图元的完整信息，并且可以确保图元之间拓扑结构的正确性。     

工程图信息系统——EDIS

介绍了ＥＤＩＳ（ＥｎｇｉｎｅｅｒｉｎｇＤｒａｆｔｉｎｇＩｎｆｏｒｍａｔｉｏｎＳｙｓｔｅｍ）系统的多层次处理工程图纸的方法以及在图形识别方面的新进展。ＥＤＩＳ通过对图纸数据的分层，使系统在处理图纸信息中能灵活结合自动处理、人工交互和智能辅助的方式，提高了处理的效率和实用性。文章还在图形识别的研究中提出了“轮廓匹配法”、推广的拓扑数据结构和图形矢量的鲁棒识别方法。     

图文自动分离的方法研究

本文给出了一种新的图文自动分离算法，可以将工程图中的文字符号信息与图形信息分割开来。该算法基于对“图”和“文”不同几何特性的分析，采用了不是直接提取文字而是尽量删除非文图形的新思路，对工程图中包含有的中西文、尺寸数字及特殊符号等非图文字均能处理，并且对工程图种类、噪声水平、字图粘连及书写方向等因素几乎不加限制。本算法可以应用于工程图自动输入系统、中西文处理与识别及其它ＣＡＤ／ＣＡＭ应用中。     

计算机图形智能评判技术研究与应用

研究了一种计算机图形智能评判技术，针对图形评判的特殊性，设计了对图形几何信息和拓扑信息提取与评判的特殊模块及智能推理机制，将 这种技术应用于全国注册建筑师试验系统的作图题评判系统，实现了对计算机图形准克、高效、智能的评分。     

水电站引水管道系统的三维重构

利用引水发电系统的平面布置与纵剖面CAD图,探讨了如何从平面图形中提取所隐含的三维信息.提出了图形分层、分色处理的基本思想与处理方法,包括对管道中心线及管道断面图层的命名规定、管道中心线交替颜色设置等.详细阐述了管道的编码规则、断面数据获取方法,以及经数据匹配生成三维构造所需几何与拓扑信息的基本原理.在KerenCAD图形系统中实现了水电站引水管道的三维重构.     

空间网格结构计算中图形输入信息数据的新的实现方法

空间网格结构计算必须输入大量的信息数据。借助ＡｕｔｏＣＡＤ图形环境,用ＶｉｓｕａｌＣ＋＋编译开发了图形输入信息数据的前处理模块,文中介绍了图形化信息的生成,着重介绍了通过对图形数据库的过滤操作实现图形化信息向数据文件转化的新方法。     

尺寸符号驱动的工程图重建方法研究

本文提出一种基于知识的高精度机械工程图二维重建方法，在研究中充分利用图纸中所蕴含的知识型信息，并注重模糊推理及模糊识别技术的应用，通过尺寸驱动及约束求解方法，实现了对图形的几何信息用拓扑信息和尺寸信息进行智能校正。     

非数值化产品形位描述模型

传统的形状及位置表示模型通常是建立在低层次的无应用意义的几何拓扑元素之上，因而无法很好地支持计算机辅助设计（ＣＡＤ）向实用化和智能化方向发展。本文提出了一种非数值化的基于约束的产品形位描述模型，并对该模型中存在的一些问题进行了深入的讨论。该模型符合设计人员实际设计思维与过程，同时也支持高层次产品设计信息以及产品的设计过程信息，因而为传统ＣＡＤ系统向新一代实用化智能化ＣＡＤ系统过渡提供了一个良好的产品形位表示模型。     

MECAD机械零件CAD软件包的研制与开发

本文介绍耻在微机上用ＡｕｔｏＣＡＤ及其智能化语言ＡｕｔｏＬｉｓｐ开发齿轮、轴系等八类常用机械零件ＣＡＤ系统。主要介绍在开发过程中采用模块化技术，人机交互技术、复杂数据库的处理、图形处理方法及图形编辑修改等技术。     

计算机辅助检验规程设计（CAIP）的研究与实现──符号信息与几何信息的过渡和集成

着重介绍了计算机辅助检验规程设计（ＣＡＩＰ）系统第二部分的开发方案、实现特色和使用优势。ＣＡＩＰ系统是ＣＡＱ与ＣＡＤ、ＣＡＰＰ、ＣＡＭ集成的纽带，该智能系统的实现融汇了面向对象、信息集成、专家系统、关系数据库管理系统、图形系统等多种技术。本文所述＂检验指导图生成＂部分，将ＣＡＱ与ＣＩＭＳ集成信息以图形方式直观地显示出来，是ＣＡＩＰ不可缺少的部分。     

基于骨架提取的拓扑优化最小尺寸精确控制

受到可制造性的约束,拓扑优化技术目前多用于结构的概念设计,因此,研究直接面向加工制造的拓扑优化方法很有必要。该文基于启发式BESO(Bi-directional Evolutionary Structural Optimization)算法,提出了一种高效的可精确控制结构最小尺寸的拓扑优化方法。通过灵敏度插值,细化边界单元,改进BESO算法,解决边界不光滑问题;采用拓扑细化方法,提取拓扑结构的骨架构型;以此为基础,判定结构中不满足最小尺寸约束的部位,基于改进的BESO算法,实现拓扑优化结构的最小尺寸精确控制;此外,在优化过程中,通过松弛施加最小尺寸约束的方法,有效避免优化早熟问题。数值算例表明了该拓扑优化方法的有效性。     

Robust topology optimization for cellular composites with hybrid uncertainties

This paper will develop a new robust topology optimization method for the concurrent design of cellular composites with an array of identical microstructures subject to random‐interval hybrid uncertainties. A concurrent topology optimization framework is formulated to optimize both the composite macrostructure and the material microstructure. The robust objective function is defined based on the interval mean and interval variance of the corresponding objective function. A new uncertain propagation approach, termed as a hybrid univariate dimension reduction method, is proposed to estimate the interval mean and variance. The sensitivity information of the robust objective function can be obtained after the uncertainty analysis. Several numerical examples are used to validate the effectiveness of the proposed robust topology optimization method.     

自适应网格方法在Stokes问题形状最优控制中的应用

为了求解流体力学中的形状最优控制问题,本文提出了一种与最优化准则方法相耦合的自适应网格方法.优化的目标是使得流体流动的能量耗散达到最小,状态方程是Stokes问题.本算法可以在减少计算量的情况下,保证流体的界面达到较高的分辨率.最优化算法采用的是非常稳定的经典最优化准则方法,自适应网格的指示函数是通过材料分布的信息得到的.虽然本文只是考虑了Stokes问题,但所得算法可以用来解决很广泛的一类流体动力学中的形状或拓扑最优化问题.     

A design method of spatiotemporal optical pulse using level-set based time domain topology optimization

Recently, two emerging areas of photonics research, ultrafast photonics, and nanophotonics have started to come together. One of the main problems in this field is the precise control of spatial and temporal profiles of the optical pulses. In this paper, we propose a design method for user-specified spatiotemporal optical pulses using a level set-based time-domain topology optimization method. In the proposed method, the optimization problem is formulated based on time domain Maxwell equations so that the spatiotemporal optical pulses can be treated directly. The objective function is defined using the envelope information of the pulses, and an efficient way to calculate this information, based on calculations of the complex electromagnetic field, is introduced. A level set-based topology optimization method is applied to obtain optimized configurations. Using the proposed method, the spatiotemporal user-specified pulse profiles can be designed by modifying the structural details of the nanostructures through which the pulses propagate. As a simple example, we demonstrate that the optimized structures focus optical pulses into a single or multiple focal points with a user-specified pulse-width. The results show that the proposed method is able to design highly controlled spatiotemporal optical pulses by engineering the nanophotonic structure.     

Robust topology optimization under load position uncertainty

The topology optimization problem of a continuum structure on the compliance minimization objective is investigated under consideration of the external load uncertainty in its application position with a nonprobabilistic approach. The load position is defined as the uncertain-but-bounded parameter and is represented by an interval variable with a nominal application point. The structural compliance due to the load position deviation is formulated with the quadratic Taylor series expansion. As a result, the objective gradient information to the topological variables can be evaluated efficiently in a quadratic expression. Based on the maximum design sensitivity value, which corresponds to the most sensitive compliance to the uncertain loading position, a single-level optimization approach is suggested by using a popular gradient-based optimality criteria method. The proposed optimization scheme is performed to gain the robust topology optimizations of three benchmark examples, and the final configuration designs are compared comprehensively with the conventional topology optimizations under the loading point fixation. It can be observed that the present method can provide remarkably different material layouts with auxiliary components to accommodate the load position disturbances. The numerical results of the representative examples also show that the structural performances of the robust topology optimizations appear less sensitive to the load position perturbations than the traditional designs.     

Optimal design of piezoelectric microstructures

Application of piezoelectric materials requires an improvement in their performance characteristics which can be obtained by designing new topologies of microstructures (or unit cells) for these materials. The topology of the unit cell (and the properties of its constituents) determines the effective properties of the piezocomposite. By changing the unit cell topology, better performance characteristics can be obtained in the piezocomposite. Based on this idea, we have proposed in this work an optimal design method of piezocomposite microstructures using topology optimization techniques and homogenization theory. The topology optimization method consists of finding the distribution of material phase and void phase in a periodic unit cell, that optimizes the performance characteristics, subject to constraints such as property symmetry and stiffness. The optimization procedure is implemented using sequential linear programming. In order to calculate the effective properties of a unit cell with complex topology, a general homogenization method applied to piezoelectricity was implemented using the finite element method. This method has no limitations regarding volume fraction or shape of the composite constituents. Although only two-dimensional plane strain topologies of microstructures have been considered to show the implementation of the method, this can be extended to three-dimensional topologies. Microstructures obtained show a large improvement in performance characteristics compared to pure piezoelectric material or simple designs of piezocomposite unit cells.     

Topology optimization of plate/shell structures with respect to eigenfrequencies using a biologically inspired algorithm

In this article, a novel approach is presented to perform topology optimization in a simple and explicit way. The method capitalizes on the use of a bio-inspired algorithm to represent topology, leading to more flexible optimization solutions along with explicit structure representation. To avoid remeshing upon design changes, a special treatment called the enhanced stiffness transformation approach (ESTA) is introduced to transform the stiffness and mass matrices of the growing stiffener into a set of equivalent stiffness and mass matrices. In this way, stiffeners are separated from the finite element mesh and can grow in an arbitrary direction to form an optimized layout solution. Notably, this approach incorporates more geometric information into topology optimization, which improves the clarity of stiffener layouts. Finally, the effectiveness of the proposed method is illustrated with two examples of maximum eigenfrequency design of plate/shell structures.     

Topology optimization of tensegrity structures under compliance constraint: a mixed integer linear programming approach

A tensegrity structure is a prestressed pin-jointed structure consisting of discontinuous struts and continuous cables. For exploring new configurations of tensegrity structures, this paper addresses a topology optimization problem of tensegrity structures under the compliance constraint and the stress constraints. It is assumed that a cable loosens and loses the elongation stiffness when its tensile prestress vanishes due to the applied external load. It is shown that the topology optimization problem can be formulated as a mixed integer linear programming (MILP) problem. The proposed method does not require any connectivity information of cables and struts to be known in advance. Numerical experiments illustrate that various configurations of tensegrity structures can be found as the optimal solutions.     

OPTIMAL STRUCTURAL TOPOLOGY DESIGN USING THE HOMOGENIZATION METHOD WITH MULTIPLE CONSTRAINTS

In applications of the homogenization method for optimal structural topology design the solution is obtained by solving the optimahty conditions directly. This reduces the computational burden by taking advantage of closed-form solutions but it restricts the optimization model to having only one constraint. The article develops a generalized class of convex approximation methods for mathematical programming that can be used for the optimal topology homogenization problem with multiple constraints in-eluded in the model, without substantial reduction in computational efficiency. A richer class of design models can be then addressed using the hotnogenization method. Design examples illustrate the performance of the proposed solution strategy.