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With the continuous advancement of technology many embedded and real time systems require increasingly larger amount of information to be handled and managed in a timely manner. Thus, an efficient data management mechanism is necessary and that is why there is a noticeable interest in merging standard database technology and real-time technology recently. It is very difficult to achieve guaranteed real-time database services because various components can compete for system resources. Our objective is to design an experimental real-time database system which would be suitable enough to study the most important real-time database issues. Proposed system can help us to understand the cffcct of various database components on system performance and to identify the most important factors

Real-time control systems are often distributed, with complex data sharing requirements. A method is proposed using a distributed real-time database, extended with active rules that react to changes in the system. This database is fully replicated and nodes communicate using only the database distribution facilities. Temporal constraints at individual nodes may be met at the expense of temporary inconsistencies in the database. This paper investigates the effects of using a rulebased representation and the replicated database as a distribution mechanism for certain classes of real-time systems. Particular attention is paid to the effect of reduced consistency, assuming eventual consistency.

The paper is trying to present a distributed control system as a real-time database, based on the fact that, for computer controlled systems, state, inputs and outputs are known at some discrete moments, multiples of the system sampling period. First, some presumption are made over industrial networks on which the database could rely. Afterwards, a data classification is given. The main part of the paper describes the database architecture, data structures, internal operations, services provided, transaction and internal mechanisms for data management Finally, proofs are given that the described mechanisms ensure database consistency and prevent deadlocks.

The goal of this paper is to describe the components of our system INCOSOFT, the hard and software requirements, some implementation aspects, the differences between the software-systems of small and medium sized companies and large sized companies and the data model. Programming was done in the 4 th generation language SQLWindows, data administration was handled by SQLBase. The CIM-software runs on a PC-LAN with a central fileserver and a database-server. After the indroduction which focus the differences between software-systems for small and medium sized companies and large sized companies, the first part of the paper is dedicated to the specification of our system INCOSOFT. A description of the components of the system is given in chapter 3. The focus of the following chapter is on the implementation aspect. An overview of the result and further activities is given in the last chapter.

The need for database support for design applications has long been identified. The requirement is for a system in which the designer can efficiently and easily manage information from a variety of sources and integrate with existing and new Computer-Aided Control System Design (CACSD) tools. The problem with traditional database systems is that they do not readily support design data, which consists of many different types of information with complex relationships between these types. The object-oriented model can represent complex design components more directly than traditional systems and the user view of the world is similar to the higher level of abstraction provided by an object-oriented system. This not only allows the designer to set up the database simply in the first instance, but to extend the database setup for his particular needs. It is important that the database functions do not need to be re-written each time a change is made to the functionality of existing software and that new tools can be incorporated into the model with relative ease. To standardise on a data exchange method would help to alleviate this problem. One emerging ISO standard in this area is STEP. This paper describes an object-oriented data management system which has been designed for CACSD. The emerging STEP data exchange standard is discussed and how this can be implemented in an object-oriented database.

Real-time database systems (RTDBS) are database systems in which transactions have timing constraints such as deadlines. Paradigms used in conventional database systems are not suitable for real-time database systems. In this paper, we present an optimistic concurrency control algorithm for real-time tran-saction scheduling and a new parallel processing paradigm for real-time database operations.

The database system named DIPOS intended for use in computer-aided electric power system expansion planning is presented. The CAD system containing the DIPOS database is briefly explained in the context of the transmission network expansion planning. There are many reasons that in CAD applications we should rather think about specialized or problem-oriented databases, which would give unique solutions in particular situations, than general purpose databases with maintenance and operation overheads. In the paper the user's view of data, user interface, database data model and physical database organization are discussed. The system is the relational database from the user's point of view but it employs the network database data model at the system level. This allows the user to have well known natural relational data model with its correctness and ability to perform Profitable relational operations, whereas the DIPOS database network data model gives additional advantages in the pre-definition of possible use patterns of the data. An example of database application is also presented.

This paper presents the design concept of an intelligent information system for verification, validation, association, and conversion of test data which are gathered at various workcells in CIM environment. The technician at each workcell enters test data into a central database. Experience has told us that the database may be erroneous due to wrong entry, wrong unit, wrong format, wrong code, and wrong scale. Thus the database must be verified and validated before it becomes useful. The data in the validated database are then grouped and categorized for the well-defined hierarchical structure. To facilitate the use of the database, the data will be dynamically reorganized to meet the needs of various users.

A small batch manufacturing system testbed, currently under construction at the U.S. National Bureau of Standards (NBS), is designed to support research in factory automation standards. One of the expressed goals of the NBS Automated Manufacturing Research Facility (AMRF) project is the specification of the interfaces which must exist between component systems of automated factories. Undoubtedly, factories will eventually be constructed from modules that are offered as "plug conlpatible" products by different systems vendors. These vendors will need a standard factory model or system architecture for planning and implementing external interfaces to their proprietary systems. This paper discusses the AMRF factory architecture in terms of five major groups of subsystems: User Data Interface Devices, Hierarchical Manufacturing Management, Network Communications, Distributed Data Administration, and Shop Floor Hardware. Fundamental concepts and implementation architecture is presented for each group of subsystems