序列二次规划在结构动力优化中的应用

本文将序列二次规划应用于受到多阶固有频率与动力响应约束的结构动力优化设计,构造了一种交替执行调频步与减重步的迭代算法,可以有效地处理不可行设计。同时采用粗糙一维搜索确定步长并求出自适应的运动极限,使算法稳定收敛到最优点,旋翼和各种断面的梁结构动力优化数值实验证明了算法的有效性。应用序列二次规划求解组合结构静力优化已取得显著效果。对受到多频率约束的动力优化设计,序列二次规划也是有效的,但实践表明动力优化设计有其特殊性,需要我们对基本的序列二次规划算法加以修改,以适应频率、动应力和动变位约束非线性程度较高、初始设计往往不可行的特点。文[4]分析了数学规划法和结构优化中处理一维搜索的不同策略,指出应当引入粗糙一维搜索以保证算法的稳定收敛及数学的严谨性,本文将这一方法应用到动力优化中。     

先进复合材料格栅圆柱壳优化设计的混合遗传算法

复合材料格栅加筋结构优化设计是一个属于多工况、多约束、连续变量和非连续变量混合的优化问题。对遗传算法与单纯形法作了相应的改进, 利用外罚函数法将受稳定性约束和应变约束的多约束优化问题转化为无约束优化。在此基础上, 提出了一种遗传算法与单纯形法相结合的混合遗传算法, 通过与其它文献结果和传统遗传算法结果对比, 证实了混合遗传算法的有效性。以受均匀侧压时复合材料格栅圆柱壳优化设计为例,分别讨论了不同格栅类型和有、无强度约束时的优化结果。分析表明, 整体稳定性是控制该结构安全度的最主要约束因素。本算法具有高效和方便的特点。      

多类约束下U型装配线平衡建模研究

现有针对U型装配线平衡问题的研究假设除了节拍约束和任务间的优先顺序关系外,不存在其它约束,实际上受生产环境、产品设计、工艺要求以及人因等多种因素的制约,在对U型装配线进行优化设计时还需满足其它约束,将各种表象不同的约束抽象为相连、相斥、相关以及工作站属性约束四类,针对多类约束下U型装配线平衡问题建立了整数规划模型,通过...     

基于Newmark法敏度计算的刚架结构动力优化

提出一种有效的求解结构最小质量设计,同时满足动位移和动应力约束的二阶优化设计方法。在有限元法和纽马克法基础上导出一种高效的动应力、动位移对设计变量一阶导数和二阶导数的算法。建立含时间参数,以结构质量最小化为目标,同时满足动位移、动应力和设计变量约束的优化数学模型,通过积分型内点罚函数将含时间参数的不等式约束优化问题转变为一系列不含时间参数的无约束优化问题。利用动位移、动应力对设计变量一阶导数和二阶导数的信息计算内点罚函数的梯度和海森矩阵,利用梯度和海森矩阵构造求解优化设计问题高效有效的二阶优化算法。算例结果表明该文的优化设计方法能获得刚架结构的局部最优设计,优化的效率高于增广拉格朗日乘子法。     

基于粒子群算法的高黏度大比重物料无轴螺旋输送机构优化设计

 为解决高黏度大比重物料无轴螺旋输送机的螺旋叶片变形问题,利用粒子群优化算法,以无轴螺旋叶片刚度变形最小为优化设计目标,构建了基于粒子群算法的无轴螺旋叶片优化设计模型.应用构建的理论模型,进行了实例设计,并通过实验研究进一步证实该设计方法具有先进性和实用性．将智能算法应用于机械优化设计,为该领域研究提供新思路．     

面向安全卫生壁垒的食品包装机械设计技术

安全卫生规定成为技术壁垒将是食品包装机械发展的新趋势。分析和探讨了以安全卫生为核心目标,食品包装机械设计需掌握和运用的安全设计技术、卫生设计技术、绿色设计技术、现代高新技术和计算机仿真设计技术,并指出了提高安全卫生设计水平是影响我国食品包装机械在新一轮竞争中成败的重要因素。     

离散变量结构优化设计的拟满应力遗传算法

以力学准则法为基础,提出了一种求解离散变量结构优化设计的拟满应力方法;这种方法能直接求解具有应力约束和几何约束的离散变量结构优化设计问题。通过在遗传算法中定义拟满应力算子,建立了一种离散变量结构优化设计的混合遗传算法拟满应力遗传算法。算例表明:这种混合遗传算法对于离散变量结构优化设计问题具有较高的计算效率。     

基于自由度分析的三维模型几何约束求解

针对三维几何约束模型的求解问题,在充分研究了二维几何约束模型自由度分析技术的基础上,采用几何推理的方法,给出了一种三维模型几何约束求解的自由度分析算法,该算法可归纳为活动分析和场所分析两个过程.算法为三维几何约束模型提供了一种求解方案,解决了过约束和欠约束状态时的约束求解问题,并展示了一个实例.     

基于粗糙熵的电信客户行为推理研究

如何利用电信客户的行为数据来对电信客户的流失进行预警一直是电信客户流失管理的重点与难点。对电信客户的行为特点进行了分析,给出了电信客户的行为属性以及状态属性,提出了基于粗糙熵的电信客户行为推理算法,并对湖北某电信运营商的客户行为数据进行了实证分析,得到了电信客户行为属性与状态之间的关联规则。证明了该算法可以有效地利用电信客户的行为数据对客户的状态进行有效的知识推理。     

含静、动力约束的复合材料结构的优化设计

本文利用序列二次规划准解析法,解决了含几何角度变量和厚度变量的复合材料层板的结构优化问题.设计约束包括结构的位移约束,应力约束和固有频率约束.基于虚功原理,对有限元分析中刚度矩阵和几何角度变量成非线性关系的情况,给出了统一的应力,位移约束的灵敏度计算公式,对固有频率的导数计算也作了推导.计算结果表明,序列二次规划准解析法对于解决含静,动力约束的复合材料层板的优化设计问题,具有较高的计算效率;并且,在复合材料层板的优化设计中增加何几角度寻优(即层板直三维空间的最佳几何位置)能获得更为新意的减重效果.      

多约束下的载人潜器舱内计算机辅助工效设计系统研究

为了能使载人潜器舱内工效设计人员加深对多约束条件下舱内人员的生理、心理和环境约束条件的理解,有效地辅助设计方案的智能生成与优化.提出了基于虚拟人体模型参数作为布局设计解空间的参数获取方法、基于遗传算法的舱内人-机界面布局设计方案计算智能求解方法、基于知识推理的舱内色彩工效设计方案获取方法和基于粒子群算法的载人舱工效设计方案智能优化方法,以此为基础,应用UG二次开发和数据库技术,开发了载人潜器舱内人机工效设计计算机辅助系统.通过设计实例的人机工效布局和色彩设计与方案优化验证了该系统的可行性.     

二叉树型知识获取与推理技术研究

通过应用计算机可视化技术、二叉树表达技术、XML数据库技术和推理技术,开发了基于可视化技术的专家知识采集与知识推理系统.其推理机利用了无状态连续推理技术,提高了有害生物知识采集和系统推理的效率.系统具有简单易用的特点,植保专家可以方便地利用该系统构建有害生物调控知识库.     

基于模块化设计思想的镀膜机快速设计研究

以大规模定制思想为背景,提出了一种镀膜机快速设计方法,阐述了镀膜机模块化设计的方法,研究了镀膜机的模块划分方法、知识工程的应用、实例的推理技术,通过镀膜机的设计流程分析,说明了模块化设计形成的特点。证明了运用模块化设计思想能很好地解决客户的个性化定制需求与产品开发周期较长的矛盾。     

Determination of ranged sets of design specifications by incorporating design-space heterogeneity

Setting design specifications (targets) is a critical task in the early stages of the design process. Flexible targets can accommodate uncertainty and changes in design by postponing design commitments and preserving design freedom. In this article, a new method is developed for obtaining a ranged set of design specifications that meets design criteria whilst incorporating design-space heterogeneity; meaning some areas in the design attribute space are more achievable than the others. The proposed method has two notable features. First, a quantization algorithm based on rough-set theory is used to decompose a design attribute space into sub-regions on the basis of how well they meet design criteria. Second, a new design-flexibility measure is used as a metric to select the most desired ‘target region’ on the bases of both the size of the region and the influence of potential design alternatives on overall achievability. The proposed approach enhances the capacity of a design system to adapt to evolving design knowledge, as well as to unexpected changes. The proposed method is demonstrated by a numerical example and the design of a domestic blender.     

药筒精密成形工艺数字化设计系统

介绍了药筒工艺数字化设计系统的特点、设计流程和各功能模块的主要功能。该系统在药筒成形工艺和模具设计过程中融合了基于规则的推理与基于实例的推理,可智能完成工艺参数计算,半制品与模具参数化建模,同时为设计者提供有效的精密成形工艺设计知识和经验帮助,大幅提高了该类零件成形工艺和模具设计效率。     

基于案例的文化创意产品设计方法研究

针对文化产品的造型设计,将与产品造型相关的设计元素细分为功能、行为、文化、情感和构造法五个方面,结合基于案例的设计(case-based design,CBD)技术、遗传算法以及形状文法知识,建立文化创意产品设计概念原型系统并对文化创意产品进行引导设计。提出产品造型相关设计元素多目标优化模型,对用户需求进行匹配操作。提出文化产品造型设计方法模型,结合产品基因树交叉操作与形状文法知识,将现代类产品与文化器物类产品的设计元素进行交叉重组。通过对产品造型相关设计元素进行深入研究,并在文化创意产品设计概念原型系统中融入基于案例的设计技术、遗传算法和形状文法的知识,辅助设计师对文化产品进行创意设计。以小音箱为例,验证了该方法的可行性,为文化产品设计提供了一种有效方法。     

Research on cultural and creative product design method based on case北大核心CSCD

Aiming at the design of cultural product modeling,design elements related to product modeling were subdivided into five aspects, including function, behavior, culture, emotion and structure method. Cultural and creative product concept prototype system was built to design culture creative products by combining case-based design technology, genetic algorithm and shape grammar knowledge. The system was built to guide designers to design some cultural products. A multi-objective optimization model of design element oriented on product modeling was proposed, and the matching operations on the user demand was made. The design method model of cultural products modeling was presented, which combined with the knowledge of product gene tree crossover operation and shape grammar, and a crossing and recombinant of design elements between modern products and cultural artifacts was made. Through the in-depth study of product modeling design elements, and integrating case-based reasoning, genetic algorithm and the shape grammar knowledge into cultural and creative product concept prototype system, it was proved that the system was able to aid the designers to make some creative designs. An example of the design on small speakers was used to verify the feasibility of this method. An effective design method on cultural product design is provided.     

A performance evaluation of three inference engines as expert systems for failure mode identification in shafts

This paper aims to present performance evaluation of three different inference engines (rule based reasoning, fuzzy based reasoning and Bayesian based reasoning) for failure mode identification in shafts. This research was done with a focus on the validation cases and results after their use in failure cases from several industries where the three systems were tested under the same conditions.Each system was implemented using the same user interface and knowledge base, with different frameworks and techniques as follows: rule based inference reasoning (prolog, C#), Mamdani-fuzzy based reasoning (C, MATLAB®) and Bayesian based reasoning with a variable elimination algorithm (C, MATLAB®).The best performance was obtained using the Bayesian inference engine. The conditional probabilities give flexibility when evidence is not listed, while the fuzzy and classical IF-THEN systems depend on the rules in the inference engine.The process presented in this paper could be used for validation of any expert system or for comparison with other expert systems (inference engines) when the knowledge base is the same.     

A scheme for functional reasoning in conceptual design

An ideal functional reasoning environment should support designs of any nature, routine or innovative, at any level of detail, as well as through varying levels of detail. In this paper, three existing functional reasoning models are reviewed in this perspective. It has been found that none of these models support all of these requirements. It has been shown that a functional reasoning approach cannot guarantee the generation of solution concepts, which are combinations of known solutions, unless guided by the knowledge of existing solutions. A new model which can support design both across a level of detail and down through levels of detail has been proposed, which, using a divide and rule approach and using recursive problem redefinition while incorporating existing solutions, could support conceptual design. It is also shown that, although the generation of completely new solutions is not supported by the model, the model, when aided by a framework allowing a sustained progress of its knowledge base by transfer of knowledge from existing designs in the form of basic structures and rules of combination, could support generation of designs which otherwise would be considered unsupportable in a systematic way (innovative).     

逆向学习耦合多属性查询的图像排序/检索优化算法研究

目的提出逆向学习耦合多属性查询的图像同步排序/检索优化算法,以解决当前算法检索效率与精度不高等问题。方法引入逆向学习概念,利用复杂无损函数,设计图像检索机制,优化训练误差。考虑查询项属性相关性,将训练图像分割成多个子集,联合权重因子,构造图像排序模型。对于给定的多属性查询,文中算法可以利用查询项中隐含的单词属性完成检索。结果文中算法支持多标记查询,与当前图像排序搜索机制相比,在多属性查询条件下,文中算法具有更高的检索精度(当查全率为80%时,精度较对照组分别提高了8.3%和13.2%)与效率。结论文中算法能够支持多属性查询,能进一步增加检索精度。