一个基于约束图的参数化设计模型

基于图论的约束求解方法是目前参数化设计的主要方法,此方法已经应用于许多商品化软件中。该文提出了一个基于几何约束图的参数化设计模型,并给出了参数化模型的数据结构和约束求解算法。此算法可以有效地检查系统的过约束和欠约束情况。     

基于图形数据库的变量化设计方法

文章针对参数化技术中过约束和欠约束的求解和图形设计问题,提出了一种新的基于图形数据库的变量化设计方法。该方法依据一组变量化基本规则,采用人工智能方法,对过约束与大约束问题判断、求解,扩大了模型图的自由度,提高了图形设计的效率和可靠性。     

复杂陈述式仿真模型的相容性分析

模型的相容性分析是复杂产品多领域建模面临的一个关键问题.研究了陈述式基于方程仿真模型的方程系统过约束或欠约束判定、检测与修正策略.首先,将方程系统表示为二部图,通过二部图分解判定模型的相容性,并分离出方程系统的过约束和欠约束部分.然后,通过检测、判定与缩减过程,自动判别出过约束或欠约束发生的大致范围,并给出修正方案.所提出的策略与算法能够显著地提高用户发现与排除过约束或欠约束问题的效率,已在多领域物理系统混合建模与仿真平台MWorks中实现.     

一种欠约束草图求解方法的研究

基于约束的参数化描述及求解是计算机辅助设计研究的一个热点，欠约束图的求解是参数化设计的基本问题，为了提高欠约束草图求解的参数化设计效率，提出了一种基于隐式约束优先级的欠约束草图求解方法，并首先给出了欠约束图求解的一般方法以及欠约束图的基本特征，提出了利用隐式约束去匹配缺少的显式约束；然后将隐式约束按照一定的规则分成不同的优先级，再利用优先级高的隐式约束去匹配变动约束图中的欠约束，直到完成约束图的有向化；最后，探讨了无尺寸约束图有向化过程中的基本特点，并给出了无尺寸约束图的求解算法和应用实例。实例应用结果表明，效果较好。     

自由特征模型约束求解研究*

在对自由特征模型参数化基础上,提出一种约束求解的新方法。该方法对自由特征形体定义点进行参数化,建立几何约束图,将约束问题分解为三角形约束和四面体约束两大类,分别进行求解,定义手向性规则,利用该规则将子问题组合为全局解。在自主开发的HUST-CAIDS（哈尔滨理工大学计算机辅助工业设计系统）中实现了本算法,并得到满足设计者需求的模型。     

密集标志点集的拓扑保持变换方法*

在对自由特征模型参数化基础上,提出一种约束求解的新方法。该方法对自由特征形体定义点进行参数化,建立几何约束图,将约束问题分解为三角形约束和四面体约束两大类,分别进行求解,定义手向性规则,利用该规则将子问题组合为全局解。在自主开发的HUST-CAIDS（哈尔滨理工大学计算机辅助工业设计系统）中实现了本算法,并得到满足设计者需求的模型。     

基于有向超图的参数代表示模型及其实现

本文提出了一种基于有向超图的参数化图形表示模型．它不仅能够表示图形的尺寸约束和几何约束，而且能够支持图形拓扑结构变化和工程设计约束的表示．在交互绘制图形对象的同时直接建立参数化图形约束模型．由于在图形构造的每一步都保证约束的一致性，因此，不会出现过约束或欠约束的情况．经实践表明，该模型具有实用方便、高效可行的特点，适合于系列化产品的参数化ＣＡＤ系统建模和绘图．     

基于有向超图的参数化表示模型及其实现

本文提出了一种基于有向超图的参数化图表表示模型。它不仅能够表示图形的尺寸约束和几何约束，而且能够支持图形拓扑结构变化和工程设计约束的表示，在交互绘制图形对象的同时直接建立参数化图形约束模型。由于在图形构造的每一步都保证约束的一致性，因此，不会出现过约束或欠约束的情况。经实践表明，该模型具有实用方便、高效可行的特点，适合于系列化产品的参数化ＣＡＤ系统建模和绘图。     

一个基于图基约束集映射的参数化设计模型

文中提出了一个基于图基约束集映射的参数化设计模型 .对图基的概念作了阐述 .提出了一个适合于图基参数化的数据模型和约束集的多元组表示与映射方法 .给出了基于图基实例的约束求解方法和定位算法 ,并对计算方法作了归纳 .在此基础上 ,给出了一个基于图基的一致联动方法 .实践证明 ,基于图基联动的设计方法摆脱了传统的基于点、线、圆、圆弧低层次线素繁琐的交互设计工作 ,提高了 CAD系统的自动化程度 ,使设计人员对产品的设计、维护以及后续分析等过程都具有十分重要的意义 .     

几何因果定性推理的基本原理和算法

因果定性推理是一种通过分析描述物理系统行为和关系的约束找出系统内部各个成分之间的因果结构的推理方法．本文提出一种基于约束和变量分析的因果定性分析模型和算法．该方法在产品设计中有广泛的应用，利用这个模型和算法可较好地解决参数化设计中的几何推理问题，还可用作概念设计的工具，用于完成复杂系统设计任务的划分及定序、设计变量之间相互依赖关系分析等工作．算法具有应用性强、效率和稳定性好、支持欠约束和多解问题等优点.     

Cost optimization of composite beams using genetic algorithms

This paper presents a genetic algorithm model for the cost optimization of composite beams based on the load and resistance factor design (LRFD) specifications of the AISC. The model formulation includes the cost of concrete, steel beam, and shear studs. Two design examples taken from the literature were analyzed in order to validate the proposed model, to illustrate its use, and to demonstrate its capabilities in optimizing composite beam designs. The results obtained show that the model is capable of achieving substantial cost savings. Hence, it can be of practical value to structural designers. A parametric study was also conducted to investigate the effects of beam spans and loadings on the cost optimization of composite beams.     

Hierarchical Geometric Constraint Model for Parametric Feature Based Modeling

A new geometric constraint model is described,which is hierarchical and suitable for parametric feature based modeling.In this model,different levels of geometric information are repesented to support various stages of a design process.An efficient approach to parametric feature based modeling is also presented,adopting the high level geometric constraint model.The low level geometric model such as B-reps can be derived automatically from the hig level geometric constraint model,enabling designers to perform their task of detailed design.     

Scheduling for a share of the machine

This paper describes the mechanism used to schedule jobs and control machine use on the IBM 370/165 at Cambridge University, England. The same algorithm is currently being used in part at the University of Bradford, and implementations are in progress at the Universities of Leeds, Salford and Liverpool for the ICL 1900 series machines. The mechanism relies on allocating a share of the machine to each user (or project), and then varying the turnround time for jobs according to whether the project in question is over- or under-using its share of the machine. The approach is believed to be an original one, having a number of advantages over more conventional scheduling and control algorithms.     

Discrete cost optimization of composite floor system using social harmony search model

This paper presents a social harmony search algorithm model for the cost optimization of composite floor system with discrete variables. The total cost function includes the costs of concrete, steel beam and shear studs. The design is based on AISC load and resistance factor design specifications and plastic design concepts. Here, six decision variables are considered for the objective function. In order to demonstrate the capabilities of the proposed model in optimizing composite floor system designs, two design examples taken from the literature are studied. It is shown that use of the presented model results in significant cost saving. Hence, it can be of practical value to structural designers. Also the proposed model is compared to the original harmony search, its recently developed variants, and other meta-heuristic algorithms to illustrate the superiority of the present method in convergence and leading to better solutions. In order to investigate the effects of beam spans and loadings on the cost optimization of composite floor system a parametric study is also conducted.     

Untangling parameters: A formalized framework for identifying overlapping design parameters between two disciplines for creating an interdisciplinary parametric model

Employing an interdisciplinary approach in design is an important part of the future of architecture. Therefore, taking a step toward better understanding the overlaps between disciplines, and formalizing the process of integration between disciplines accelerates progress in the field. In examining an interdisciplinary design approach using computational design and simulation tools, while considering shell structures as a special case for spanning large-span roofs, structural and daylighting discipline are considered. The aim is to understand what are the design parameters that co-exist in the structural and daylighting design disciplines, and how may these parameters be implemented in a parametric model created by designers. The parametric model that includes discipline specific parameters can later be used for interdisciplinary performance-based design. Implementing design parameters calls for an understanding of the ways in which parameters affect design and performance. This research considers the application of parametric design methods at the early stages of design for designing high-performance buildings.     

On capacity allocation for operating rooms

This paper studies capacity planning decisions that allocate surgical specialties to operating-room (OR) days with the objective of minimizing total expected costs due to penalties for any patients who are not accommodated and for under- (i.e., idleness) and over- (i.e., overtime) usage of OR capacity. It presents a prototypical non-linear, stochastic programming model to structure relevant and practical features of the problem and four adaptations, along with associated solution approaches, with the goal of facilitating solution by overcoming the computational disadvantages of the prototype. Each of these adaptations offers advantages but is also attended by disadvantages. Computational tests compare the four adaptations and solution approaches with respect to solution quality and run time.     

基于UG二次开发的参数化建模方法

对于目前有关UG二次开发中零件的常用参数化建模方法,论文提出了两种更为简单快速的建模方法.第一种方法是以内齿圈参数化设计为例,通过先建立零件的模板模型,然后在其对话框的回叫函数中,编写代码更改参数,最后更新,实现零件的参数化.第二种方法是以超声变幅杆为例,利用UG建模环境中的JA文件录制功能,将零件的建模过程进行录制,用得到的代码在对话框的回叫程序中替代原本用API或grip开发的零件建模程序,然后将对话框的输入值与代码中模型的参数进行关联,实现零件的参数化.这两种方法的应用能有效减少设计人员的重复劳动,提高设计效率.     

基于HPGL文件的图元优化排序

HPGL文件的图形元素是以绘图人员设计的先后顺序记录于文件中,导致以此为基础进行的绘图或加工过程的无效行程大量增加且效率低下,且HPGL文件曲线图元均自动插补为大量小线段,以简单查找排序的方法处理耗时长.针对此问题,以HPGL文件记录的图形元素为对象,提出了一种利用哈希思想动态改变图元始末点及图元绘制顺序的优化算法,使其转化为DXF文件图元优化问题,进而实现了HPGL中图形元素及其控制点的优化排序并生成优化后的HPGL文件,使得以此文件为基础的绘图或加工路径得到优化.     

Parametric and semiparametric methods for mapping quantitative trait loci

Most statistical methods for mapping quantitative trait loci (QTLs) have been extensively developed for normally distributed and completely observed phenotypes. A survival model such as Cox’s proportional hazards model, or an accelerated failure time model, is the natural choice for regressing a phenotype onto a maker-type when the primary phenotype belongs to failure time. This study proposes parametric and semiparametric methods based on accelerated failure time models for interval mapping. In the parametric model, the EM algorithm (expectation maximization algorithm) is adopted to estimate regression parameters and search the entire chromosome for QTL. In the semiparametric model, the error distribution is left unspecified, and a rank-based inference is developed for the effect and location of QTL. Simulated data are used to compare the mapping performance of the semiparametric methodology with that of the parametric method, which separately selects the correct and incorrect error distribution. Analytical results reveal that the parametric estimators may be more efficient in determining the effect and location of QTL, but have obvious bias when selecting the incorrect error distribution. In contrast, the semiparametric inference is robust to the error distribution.     

跟踪对象族模型拓扑结构变化研究

提出了跟踪对象族模型拓扑变化的新算法,以建立参数和拓扑结构之间的关系,计算参数的临界值,确定模型的依赖实体,计算出模型参数的稳定区间和参数区间,最终系统准确地跟踪对象族模型拓扑结构的变化。该算法运用于自主研发的HUST-CAID系统中,提高了系统的智能性,为设计者确定参数范围提供了依据。