Security Research on Engineering Database System

Engine engineering database system is an oriented C AD applied database management system that has the capability managing distributed data. The paper discusses the security issue of the engine engineering database management system (EDBMS). Through studying and analyzing the database security, to draw a series of securi ty rules, which reach B1, level security standard. Which includes discretionary access control (DAC), mandatory access control (MAC) and audit. The EDBMS implem ents functions of DAC, MAC and multigranularity audit. DAC solves the problems o f role inheritance, right contain, authorization identify and cascade revoke, et c; MAC includes subject and object security setup rule, security modify rule and multilevel relation access operation rule, etc; Audit allows making the sub ject, object or operation type as different audit object to implement flexible a nd multigranularity audit method. The model is designed act as a security agent to access daemon database. At present, the model is implemented which runs on th e Windows 2000 environments.

APPLICATION OF GENERAL SYSTEM CAD ON ENGINES

Using modern design theory and methods comprehensively, this paper investigates a model of parameterization of engine general plan design (PEGPD). On the basis of engineering database, parametric drawing of longitudinal and cross section of engine can be obtained from this mode. The model is significant for improving the efficiency and quality of engine general system design. (Author abstract) 6 Refs.

A Data Manager for Engineering Applications

Efficient data management is crucial to the success of a CAD/CAM system.Traditional database 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 structured 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 environ- ment)project and as a lower level support to develop an object-oriented DBMS for mechanical engineering.

STEP Based CAD/CAM System Integration

STEP is now the international standard for the representation and exchange of product data. This paperintroduces implementation of CAD/CAM system integration using STEP in our GHCADMIS integrated system. The paper focuses on the EXPRESS complier, VDAI & SDAI, STEP neutral file mechanism engineering database and othertools for STEP or database system integration.

On Model, Memory Management and Interface in EDBMS/3

Engineering application domains need database management systems to supply them with a good means of modeling, a high data access efficiency and a language interface with strong functionality. This paper presents a semantic hypergraph model based on relations, in order to express many-to-many relations among objects belonging to defferent semanic classes in engineering applications. A management mechanism expressed by the model and the basic data of engineering databases are managed in main memory. Especially, different objects are linked by different kinds of semantics defined by users, therefore the table swap, the record swap and some unnecessary examinations are reduced and the access efficiency of the engineering data is increased.C language interface that includes some generic and special functionality is proposed for closer connection with application programs.