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.     

“数据库回收站”的工作原理和实现方法

该文分析了数据库安全性的缺憾,创造性地提出了“数据库回收站”的数学模型、工作单元和实现方法。它方便易行,可移植性强,不仅适用于信息管理系统,也适用于数据库管理系统及其前台开发工具的开发。     

A Data Manager for Engineering Applications

Efficient data management is crucial to the success of a CAD/CAM system.Traditional databas systems,designed to deal with only regular and structural data,cannot efficiently manage design data.In this paper,we present a data manager called EDBMS/2,which has been developed by our laboratory for engineering support applications.EDBMS/2 has a data model that combines features of both relational and semantic ones and owns flexible abilities for modeling engineering data,such as variable-length data processing,integrated management of structuresd data and unstructured data,and composite object handling.Mechanisms based on DBV and DBV graph concepts,proposed in EDBMS/2 ,make EDBMS/2 own powerful abilities for version management and run efficiently.By now,EDBMS/2 has been used successfully in EDCADS(integrated Electronic Devices CAD environment)project and as a lower level support to develop and object-oriented DBMS for mechanical engineering.     

化工工艺CAD数据库设计

本文对化工工艺辅助设计中的数据库及其管理系统的功能，构成和发展趋势作了较为全面的论述，并在此基础上提出化工工艺ＣＡＤ数据库及其管理系统的设计原则，方法，同时开发了此数据库及其管理系统。     

Query triggers for XML DBMS: Efficient implementation based on shadow mechanism

Active database systems extend functionality of traditional database systems with powerful mechanisms of triggers (or active rules) support. Triggers provide a uniform and convenient base that can be used for realization of internal DBMS functions, such as support of integrity constraints, representations, access authorization, statistics gathering, monitoring and notifications and for higher efficiency of external applications. Among representative examples of external applications that can be based on the usage of properties of active DBMS are data-intensive expert systems and workflow management systems. Today, the majority of industrial relational DBMS already support triggers, while XML DBMS, which are comparatively new, lack such functionality. Expansion of the XML DBMS application field and its usage in constructing complex application system stimulates appearance of new research works aimed at extending the functionality of XML DBMS by trigger support.In this paper, the authors define a special type of triggers for XML DBMS—XML triggers responding to data retrieval—and propose methods for their implementation. The paper also discusses examples of applications where XML query triggers occur to be useful and gives review of existing research works in this area.     

An integrated data base management system for engineering applications based on an extended relational model

Engineering analysis and design of complex systems require the use of large software components. Development, maintenance, and extension of such a software system needs modern design and implementation techniques. Usually a large amount of data is generated. Flow of data is also quite complex, adding further complications in maintenance and extension of the software. A sophisticated data base management system (DBMS) is needed to support data handling during the run-time environment as well as for the integration of various software components. Design and development of such a DBMS needs new concepts and ideas such that efficiency of calculations is not sarcrificed. Degradation in efficiency due to the use of a DBMS can hinder large-scale applications. The paper describes a generalized relational model to handle large matrices and tables that are encountered in numerous engineering applications. A DBMS based on the model is designed and implemented. The system supports run-time data management as well as data sharing among software components. A preliminary evaluation of the system against some existing ones reveals the new concept and design to be quite appropriate for engineering applications. The system is very efficient and compact. Some details of design and performance of the system are given and discussed.     

Seeking intelligent product development—an integrator environment based on STEP

Rapid Prototyping (RP) is an emerging technology with different applications in the cycle of product and process development used during the conceptual and specification phases. To support it, the usage of a Data Base Management System (DBMS) and an Expert Systems (ES) are important to manage the data, support the identification of errors and check product conformance and production viability during this cycle, seeking intelligent product development. The underlying concept of RP and ES is very straight forward, but still exists a major problem that concerns the integration in the CAD/CAM environment. CAD data can have a variety of formats depending on the model used in the CAD system, as well as on ES' data and knowledge structure, that usually relies on the expert system shell's where it was developed. To support and speed up the integration process of these tools in a manufacturing environment, is essential to have an integrator environment where a standard is adopted for the data and knowledge exchange process, providing the software applications with a neutral format interface, becoming these tools open and standard compliant, ready to be used in any other standard environment. UNINOVA, in the scope of European and National projects, developed a STEP-based Platform for Integration of applications (SIP) to support and aid the software integration in industrial environments using the standard ISO10303-STEP, already used in different industrial domains. This paper addresses the integration aspects using STEP within industrial environments from the technical point of view, and proposes an architecture and a toolkit for the integrator environment, highlighting the implementation efforts required to have RP technology, ES and DBMS focused towards a STEP-based intelligent product development.     

Data structures and DBMS for computer-aided design systems

The structures for the storage of data in CAD systems influence to a large extent the effectiveness of the system. This paper reviews the wide range of data structures and database management systems (DBMS) available for structuring CAD data. Examples of basic data types are drawn from the MODULA-2 language. The relationship between these basic data types, their composite structures and the classical data models (on which many DBMS are based) is discussed, and the limitations of existing DBMS in modelling CAD data highlighted. A set of requirements for CAD database management systems is drawn up and the emerging role of product models (which seek to encapsulate the totality of data elements required to define fully an engineering artefact) is explored.     

SUN工作站电网调度系统中数据库管理系统的设计与实现

本文介绍以电网调度自动化为背景，基于ＳＵＮ工作站设计并实现的一个数据库管理系统，该系统使数据根据存取速度要求被选择以内存共享段形式或磁盘文件形式存储，由系统提供统一的定义模式和操纵模式，本文主要从数据库词典管理，内存数据管理，磁盘数据管理三方面介绍系统设计的实现方法，并从中探讨在ＳＵＮ／Ｕ－ＮＩＸ环境下实现记录实时，快速存取的技术和方法。