Encapsulation of geometric functions for ship structural CAD using a STEP database as native storage

It is difficult to support collaborative design with a conventional ship CAD system that manages design information using files. The file storage, however, can be replaced with a commercial database management system. This paper describes OpenDIS, which is an interface between the geometric modeling kernel and the DBMS. The main purpose of OpenDIS is to implement a CAD system that has the STEP database as the native storage. A prototype CAD system has been implemented using the OpenCascade geometric modeling kernel and ObjectStore, a commercial object-oriented DBMS. The STEP methodology is used for the database schema. This CAD system has been applied to the hull design process of a ship in order to verify the usefulness of the interface.     

CAD-integrated engineering-data-management system for spring design

In an iterative design process, a large amount of engineering data needs to be processed. Owing to the limitations of traditional software, the engineering data cannot be handled simultaneously and are usually divided into geometric and non-geometric data in order to be managed by separate systems. In the spring industry, which requires repeated definition of complicated shapes, design engineers need special interfaces for efficient product design and drafting. In this paper, the CAD-integrated engineering-data-management system is developed and implemented for spring design, in order to simplify the drafting and data-management processes. This research focuses on three main issues that can be also applied to other applications, particularly for component designs. These issues include: (1) product model definition, (2) CAD-database communication, and (3) human-machine interface development. With the definition of product model, the system identifies which data should be accessed from data files to generate the proper drawings, and which database structure should be constructed for the application domain. By the use of CAD-database communication, when engineers modify the geometric or non-geometric parameters of a product design, these parametric values can be simultaneously updated in the database. Furthermore, the support of human-machine interface enhances the efficiency in routine manipulation of support engineering data management and design/redesign processes.     

基于三维实体模型的钢结构工业厂房CAD/CAM软件后处理系统

为提高钢结构工业厂房设计的准确性、精确度和工作效率,为某钢结构工业厂房CAD/CAM软件研制出基于三维实体模型的后处理系统.该系统基于面向对象的编程技术,抽象出描述实际结构零件几何信息、结构特征和设计条件的智能型实体对象.将对象以及对象之间的层次关系和逻辑关系存储在AutoCAD图形数据库中,形成三维实体模型,用于直观、准确和完整地表现具有复杂空间关系和细部构造的真实结构;实现数据库对象的建立、编辑、查询、显示和数据整理等操作.该系统结合具体结构形式的特点,实现用于施工图设计和深化设计的全部关键功能.     

A feature-based database evolution approach in the design process

Design data are assigned in geometric and non-geometric form in order to meet design requirements. These data and information must be encapsulated in a data structure that has significance for design applications in each design process phase. The main goal of this research is to find design data groups that represent each mechanical design phase, which will be called phase's design signature. In addition, current data should be an evolution of the geometric and non-geometric information of the previous design phase. In this paper, the purpose is to identify and model a set of design features that encapsulate the design data and their transformations which occurred during the mechanical design phases. This database must capture the designer's intents that can be modeled and implemented using feature-based model in the conventional CAD systems, object-oriented modeling, and Java classes.     

Five Steps to Construct a Model of Data Allocation for Distributed Database Systems

The allocation of data to nodes in a computer communications network is a critical issue in distributed database design, specially in wide area network where optimizing the distributed queries is the main objective. Numerous models of data allocation have been presented so far (Ceri and Pelagatti, 1986; Lee et al., 1994; Apers, 1988; Mahmood et al., 1994; Theel, 1994; Saha and Mukherjee, 1994; Walfson and Jajodia, 1995), but no optimal or universally accepted algorithm exists yet, and very few algorithms have been implemented to date (Rob and Cornonel, 1993). In this paper a method to construct a model of data allocation for distributed database system has been proposed. The adopted method for the construction of the data allocation model leads to an efficient model of its kind. The proposed model not only solves distributed database design problem, but also solves distributed database maintenance problem by covering initial allocation and post allocation of the data. The efficiency of proposed model has been proved by comparing proposed model with other relevant models.     

An object-oriented database management system for computer-aided design of tall buildings

An effective database and database management system is the key to the success of an integrated approach to software engineering applications in general, and Computer-Aided Design (CAD) for structural applications in particular. Due to the inherent nature of CAD data such as dynamic modeling, a wide range of data types, large data volume, etc., the traditional database models, such as hierarchical, network and relational models, are unable to handle the aforementioned applications satisfactorily. An object-oriented data modeling is known to be the most effective approach. However, many of the commercial object-oriented databases are designed for information management, and they are inadequate for CAD application due to the different features of the object-hierarchy and varying data management objectives during the design cycles. This paper presents a hierarchical index-based object-oriented database management model for CAD applications. To deal with the object hierarchy encountered in CAD for the design of tall buildings, the proposed database consists of several salient features: a hierarchical object model, its related storage structure, a data dictionary, a class factory and an index system. The proposed database management model has been implemented into an integrated CAD system for design application of tall buildings.     

船舶产品设计(SPD)系统

为打破国外船舶设计系统对我国船舶设计的垄断,提高我国船舶设计、建造的创新能力,开发具有我国自主知识产权的船舶产品设计(Shipping Product Design, SPD)系统. 该系统基于OpenGL开发具有自主知识产权的三维CAD图形平台,具有船体结构设计、管系设计、风管设计、电气设计、铁舾件设计和涂装生产设计等功能. SPD系统具有如下特点:能保持三维模型与二维图纸的高度一致;通过生成完整的加工制造信息实现CAD/CAPP/CAM集成,基本打通"壳、舾、涂一体化"的数字化生产线;通过生成壳、舾、涂完整的制造和管理信息,为实现船舶"设计、制造、管理一体化"奠定基础;通过实体和参数化技术为建立具有完整拓扑关系的船舶产品模型提供有力手段;并通过与其他系统的数据接口实现异构CAD的数据和信息集成,为厂、所协同设计创造技术条件等. SPD系统推广应用表明它有助于现代造船模式的推进和数字化造船目标的实现.     

新一代几何造型系统—GEMS4.0

ＧＥＭＳ４．０是清华大学ＣＡＤ中心在工作站上用Ｃ语言开发的新一代几何造型系统。和９０年代初问世的第三代几何造型系统相比，它具有如下特点：基于线框，表面，实体和特征表示的非流形造型；具有参数化设计，变量几何，尺寸驱动；扫描面，自由曲面和雕塑面用非均匀有理Ｂ样条（ＮＵＲＢＳ）表示，几何数据及属性的文件传送和数据库存取基于国际标准ＳＴＥＰ；基于窗口环境，面向对象的事件驱动和数据表格驱动的系统结构有利于开     

分布式飞行器气动数据库系统的设计与实现

在飞行器概念及初步设计中,气动数据库起着非常重要的作用,利用它可以快速而经济地估算出飞行器结构设计中的各种气动特性.根据飞行器设计和飞行仿真的实际需要,基于COM/DCOM技术,采用模块化的设计方法,完成了飞行器气动数据库系统框架的设计与开发.实现了飞行器气动数据的管理,同时也实现了飞行器数据在局域网环境下多个应用程序或用户共享.     

Generalized Query-By-Rule: a heterogeneous database query language

This paper describes the design and implementation of a high-level query language called Generalized Query-By-Rule (GQBR) which supports retrieval, insertion, deletion and update operations. This language, based on the formalism of database logic, enables the users to access each database in a distributed heterogeneous environment, without having to learn all the different data manipulation languages. The compiler has been implemented on a DEC 1090 system in Pascal.     

基于GIS的灾害应急管理系统的数据集成研究

常用的关系数据库缺乏直接管理空间数据的成熟通用方案。借助于空间数据库引擎(SDE)技术,扩展关系数据库功能,使关系数据库成为业务数据和空间数据的统一存储管理平台,并在此基础上建立基于Geodatabase模型的灾害应急管理系统数据库,对系统数据整体结构进行研究设计,解决了空间数据和业务数据的关联问题,实现灾害应急管理系统空间数据和业务数据的无缝集成和一体化存储。该方法已在省级应急管理信息示范平台上成功应用。     

Increasing capabilities of geometric modelling systems

Geometric modelling is the basis for design and technological planning. The integration of these tasksis the goal of the Norwegian-German APS project (Advanced Production System). In this project, the geometric model is created as a module within a solid model that handles analytic and nonanlytic geometry. The module has two interfaces: to the object-oriented operational database and to applications via a geometry-definition interface that will be enlarged to become an application interface. The geometric module can be integrated into vendor environments which normally have two-dimensional capabilities. The functional capabilities are based in COMPAC and the GPM-sculptured surface system. Both systems are merged in such a way that the data structures are integrated and one database management system is used.     

The Database Designer's Workbench

The Database Designer's Workbench is a graphics-oriented decision support system for database design, providing designers with a convenient environment for specifying database structures and experimenting with different design strategies. A prototype version has been implemented on the Honeywell Multics system using the IBM Personal Computer as the interface. Tools for conceptual design and distributed data allocation are provided. This paper describes the Workbench design objectives, system architecture, and current status.     

The effect of graphic style on data model interpretation

Abstract. Graphic data models are commonly used as a tool for presentation of information structures in the design, implementation, use and maintenance of the databases that support information systems. The methods proposed for database design assume that the use of graphic data models will enhance understanding of system specifications by both the end-users and the implementers of the system. For this assumption to hold, the information presented in the graphic data model must be readily comprehensible so that the design, represented by the model, can be confirmed and implemented correctly. The lack of standard representations for graphic models has led to a variety of graphic styles. To date, there has been little focus on studying the effect graphic style has on model comprehension. We have studied the effect of three graphic styles proposed for data models on model legibility and interpretation. Our study shows a significant variation in model interpretation that can be attributed to the graphic syntax used. Graphic style appears to influence which model elements are included in the interpretation, as well as the way data models are read.     

TRIBON系统中船舶管系产品的产品结构管理

在面临机遇和挑战的今天,各造船强国大力发展先进制造技术,我国造船业也迫切需要自己的PDM系统;本文在PDM的功能理念基础上,建立了符合STEP标准的产品结构数据模型,研究了从造船集成系统TRIBON中提取管系产品数据的几种方法．并实现了基于图视化产品结构树和表格化产品结构数据多功能视图（不同应用的BOM表）对设计过程中的船舶管系产品数据的组织和管理,对实施我国的PDM技术具有重要的意义。     

Implementation of an interactive relational graphics database

The benefits that accrue from the use of design database include (i) reduced costs of preparing data for application programs and of producing the final specification, and (ii) possibility of later usage of data stored in the database for other applications related to Computer Aided Engineering (CAE). An INTEractive Relational GRAphics Database (INTERGRAD) based on relational models has been developed to create, store, retrieve and update the data related to two dimensional drawings. INTERGRAD provides two languages, Picture Definition Language (PDL) and Picture Manipulation Language (PML). The software package has been implemented on a PDP 11/35 system under the RSX-11M version 3.1 operating system and uses the graphics facility consisting of a VT-11 graphics terminal, the DECgraphic 11 software and an input device, a lightpen.     

A database system of mechanical components based on geometric and topological similarity. Part I: representation

A database of mechanical components is an important issue for some manufacturing activities such as cost estimation, process planning, and design by case-based reasoning. In this paper, we give the representation scheme of the CAD model in such a database. Components are represented using attributed graphs in which the nodes correspond to the surfaces of the component and the links correspond to the edges of the component. The graph is based on the standard for the exchange of product information (STEP) physical file of the component. STEP file should be unique for a single component regardless of the underlying CAD system. The process of creating the graph of a component constitutes two sub-tasks: (i) importing the CAD model from the CAD system in STEP format and (ii) transforming the STEP data into attributed graph-based representation. The graph and its attributes describe the topology of the component completely together with some geometric data that are not dependent on any coordinate system such as surface type and curve type. These geometric data are helpful in the retrieval and matching processes in the database.     

非正则精确模型的布尔操作

为了加强造型系统的表达能力,实现对线框模型、曲面模型和实体模型的统一表示和操作,该文采用非正则精确模型作为几何对象表示的数据结构,并给出了相应的布尔操作实现算法,在保证效率和精确性的同时确保鲁棒性是算法的目标.作为一个特征造型系统的几何核心,该算法已经在基于NT平台的特征造型系统GS-CAD98中实现.     

Generalisation log for managing and utilising a multi-representation spatial database in map production

This paper describes a data model for logging map generalisation process information to facilitate data authentication and update propagation in a multi-representation spatial database environment. Generalisation is modelled as a directed acyclic diagram of prioritised generalisation process instances, which is further divided into independent operations as the atomic functional unit for generalisation. Generalisation parameter values and the roles of features in operations are stored. The full generalisation history of each feature may be traced for data authentication and quality analysis, or for update propagation. This model also includes the design of a feature versioning mechanism. In addition, OSGenLog, a set of platform-independent APIs to create generalisation logs, has been implemented in Gothic object-oriented database management system.     

基于元数据和XML的信息抽取与集成技术研究

为了得到统一的数据形式以利于数据操作和处理,提出了采用基于元数据的模板定制技术以实现信息抽取的方法．该方法有效地实现对非结构化文本的信息提取,将抽取信息转换为统一的XML格式,然后将XML格式的信息集成到关系数据库中．本方法在某造船厂的企业信息化中得到成功应用,为解决企业的信息集成问题提供了一种面向Word文档的新方案．