Data structures and software tools for the computer aided design of control systems: a survey.

CAD software can be structured as a set of modular 'software tools' only if there is some agreement on the data structures which are to be passed between tools. Beyond this basic requirement, it is desirable to give the agreed structures the status of 'data types' in the language used for interactive design. The ultimate refinement is to have a data management capability which 'understands' how to manipulate such data types. In this paper the requirements of CACSD are formulated from the point of view of Database Management Systems. Progress towards meeting these requirements in both the DBMS and the CACSD community is reviewed. The conclusion reached is that there has been considerable movement towards the realisation of software tools for CACSD, but that this owes more to modern ideas about programming languages, than to DBMS developments. The DBMS field has identified some useful concepts, but further significant progress is expected to come from the exploitation of concepts such as object-oriented programming, logic programming, or functional programming.

An evaluation of a new product data model

Engineering companies face many challenges today such as increased competition, higher expectations from consumers and decreasing product lifecycle times. This means that product development times must be reduced to meet these challenges. Concurrent engineering, reuse of engineering knowledge and the use of advanced methods and tools are among the ways of reducing product development times. Concurrent engineering is crucial in making sure that the products are designed with all issues considered simultaneously. The reuse of engineering knowledge allows existing solutions to be reused. It can also help to avoid the mistakes made in previous designs. Computer-based tools are used to store information, automate tasks, distribute work, perform simulation and so forth. This research concerns the evaluation of tools that can be used to support the design process. These tools are evaluated in terms of the capture of information generated during the design process. This information is vital to allow the reuse of knowledge. Present CAD systems store only information on the final definition of the product such as geometry, materials and manufacturing processes. Product Data Management (PDM) systems can manage all this CAD information along with other product related information. The research includes the evaluation of two PDM systems, Windchill and Metaphase, using the design of a single-handed water tap as a case study. The two PDMs were then compared to PROSUS/DDM. PROSUS is the Process-Based Support System proposed by [Blessing 94] using the same case study. The Design Data Model is the product data model that includes PROSUS. The results look promising. PROSUS/DDM is able to capture most design information and structure and present it logically. The design process and product information is related and stored within the DDM structure. The PDMs can capture most design information, but information from early stages of design is stored only as unstructured documentation. Some problems were found with PROSUS/DDM. A proposal is made that may make it possible to resolve these problems, but this will require further research.

Optimal design of Functionally Graded Materials using a procedural model and Particle Swarm Optimization

A new method for the optimal design of Functionally Graded Materials (FGM) is proposed in this paper. Instead of using the widely used explicit functional models, a feature tree based procedural model is proposed to represent generic material heterogeneities. A procedural model of this sort allows more than one explicit function to be incorporated to describe versatile material gradations and the material composition at a given location is no longer computed by simple evaluation of an analytic function, but obtained by execution of customizable procedures. This enables generic and diverse types of material variations to be represented, and most importantly, by a reasonably small number of design variables. The descriptive flexibility in the material heterogeneity formulation as well as the low dimensionality of the design vectors help facilitate the optimal design of functionally graded materials. Using the nature-inspired Particle Swarm Optimization (PSO) method, functionally graded materials with generic distributions can be efficiently optimized. We demonstrate, for the first time, that a PSO based optimizer outperforms classical mathematical programming based methods, such as active set and trust region algorithms, in the optimal design of functionally graded materials. The underlying reason for this performance boost is also elucidated with the help of benchmarked examples. © 2011 Elsevier Ltd. All rights reserved.

LSIS-III VLSI CAD 系统集成的研究

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

The design and verification of FPGA CAD toolset

This paper introduces a complete CAD toolset for the implementation of digital logic in a Field-Programmable Gate Array (FPGA) platform. Compared with existing academic toolsets, this toolset introduces formal verification in each step of the tool flow, especially the formal verification of the configuration bitstream. The FPGA CAD tool verification flow using Formality is presented in detail. Using plug-in technology, we have developed an integrated FPGA design kit to incorporate all tools together.

基于知识重用的服装CAD系统

针对当前CAD软件对设计知识重用支持不足且大多基于WIMP交互方式等问题,设计并实现一个基于知识重用的服装工艺设计系统。该系统框架主要包括知识推荐和知识编辑2个模块。针对知识推荐和知识编辑,分别提出基于草图相似性的实时知识推荐算法和基于笔手势的知识编辑方法,给出系统的应用实例。该系统已应用于北京某羊绒企业的生产中,实践表明该系统能改善人机交互,提高设计效率。

风光互补发电系统的优化设计（I）CAD设计方法

给出了一整套利用CAD进行风光互补发电系统优化设计的方法。为了精确确定系统每小时的运行状态，采用了更精确地表征组件特性及评估实际获得的风光资源的数学模型。为了寻找出以最小设备投资成本满足用户用电要求的系统配置，首先在风力发电机容量固定不变的前提下，计算了与该容量风力发电机匹配的不同容量的PV方阵和蓄电池所组成的风／光／蓄组合的全年功率供给亏欠率LPSP，根据总的设备投资成本最小化的原则筛选出一组与该容量风力发电机对应的满足用户给定系统供电可靠性即LPSP值的风／光／蓄组合；然后通过改变风力发电机的容量，优选出多个与不同容量风力发电机对应的既能满足用户用电要求同时总的设备购置成本又是最低的风／光／蓄组合，比较它们的成本最终唯一确定出以最小投资成本满足用户用电要求的优化的系统配置。

干旱胁迫对杨树幼苗叶片内ABA和CaM含量的影响

不同浓度PEG 6000(水势分别为-0.2、-0.6-、1.2 MPa)处理两种杨树幼苗,结果表明:随着水势的降低,叶片内ABA和CaM含量都明显增加,说明它们在植物抵抗干旱胁迫的过程中发挥重要作用。