To shorter product development time, this paper proposed an approach to developing feature based parametric product modeling systems which are suitable for integrated engineering design in CIMS environment. The archit...
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ISBN:
(纸本)0780331044
To shorter product development time, this paper proposed an approach to developing feature based parametric product modeling systems which are suitable for integrated engineering design in CIMS environment. The architecture of ZD-MCADII and the characteristics of its each module are introduced in detail. ZD-MCADII's product data is managed by an object-oriented database management system OSCAR, and the product model is built according to the standard STEP. For the product design is established on a unified product model, all product data are globally associated in ZD-MCADII. ZD-MCADII provides various design features to facilitate the product design, and supports the integrity of CAD, CAPP and CAM.
For a complex object model, a form of range restriction, called specialization constraint (SC), has been proposed, which is associated not only with the properties themselves but also with property value paths. The do...
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For a complex object model, a form of range restriction, called specialization constraint (SC), has been proposed, which is associated not only with the properties themselves but also with property value paths. The domain and range of an SC, however, were limited to single classes. In this paper, SCs are generalized to have sets of classes as their domains and ranges. Let SIGMA be a set of SCs, where each SC in SIGMA has a set of classes as its domain and a non-empty set of classes as its range. It is proved that an SC is a logical consequence of SIGMA if and only if it is a finite logical consequence of SIGMA. Then a sound and complete axiomatization for SCs is presented. Finally, a polynomial-time algorithm is given, which decides whether or not an SC is a logical consequence of SIGMA.
The paper concerns with the application of object-oriented modelling to the development of real-time control software for FMS. object- oriented model integrates the features of object-oriented database, features of re...
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The paper concerns with the application of object-oriented modelling to the development of real-time control software for FMS. object- oriented model integrates the features of object-oriented database, features of real-time system and features of artificial intelligence aspects. The goal is to develop intelligent decision making logic for automatic creation of the control actions in both the standard and the nonstandard (error) situations. The knowledge is represented by the rules and the constraints. Three type of rules are described in the paper: process rules (create the dynamic model of the devices), production plan rules (define the production sequence of the technological operations), and expert knowledge rules (create reasoning model for solving the fault situations). The cooperation among these rules is also discussed in the paper.
The hypermedia work discussed here is derived from our participation in the DeVise project at Aarhus University in Denmark. Developing tools to support cooperative design in a variety of application areas including la...
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The hypermedia work discussed here is derived from our participation in the DeVise project at Aarhus University in Denmark. Developing tools to support cooperative design in a variety of application areas including large engineering projects is one of the project's goals. The primary user organization in the Esprit projects EuroCoOp and EuroCODE, from which the DeVise group receives partial funding, is constructing one of the world's largest tunnel and bridge ''links.'' The use settings for our tools are characterized by cooperative work distributed over time, space and hardware platforms. Cooperative work in engineering projects raises several requirements for hypermedia, such as: shared databases, support for awareness among users of shared materials, access from multiple platforms, open architecture for integration of applications, portability, extensibility and tailorability. The possibility for integrating applications already developed for the engineering domain with hypermedia facilities was a particularly important requirement to meet. For a detailed discussion of our use setting, the engineering project, and its CSCW and hypermedia requirements, see [5],
We propose a visual query language object query diagram (OQD) for object-oriented databases (OODBs). Unlike other approaches for OODBs, in which a class is used as a primitive entity for query specification, in OQD we...
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We propose a visual query language object query diagram (OQD) for object-oriented databases (OODBs). Unlike other approaches for OODBs, in which a class is used as a primitive entity for query specification, in OQD we specialize a class as a number of object sets, each of which is a domain of an attribute in the class. An object set is the primitive entity of designation in a query. OQD helps make queries simple by specifying a query without a complex path expression and give a better support for query optimization by removing the repetitive use of path expression and grouping the conditions which apply to a single class. Moreover, the basic structure of OQD derived from a schema graph can be easily extended to express a complex query because the entities of designation in a class, i.e. object sets, are isolated from each other.
The objective of a multidatabase system is to provide a single uniform interface to accessing multiple independent databases being managed by multiple independent, and possibly heterogeneous, database systems. One cru...
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The objective of a multidatabase system is to provide a single uniform interface to accessing multiple independent databases being managed by multiple independent, and possibly heterogeneous, database systems. One crucial element in the design of a muitidatabase system is the design of a data definition language for specifying a schema that represents the integration of the schemas of multiple independent databases. The design of such a language in turn requires a comprehensive classification of the conflicts (i.e., discrepancies) among the schemas of the independent databases and development of techniques for resolving (i.e., homogenizing) all of the conflicts in the classification. An earlier paper provided a comprehensive classification of schematic conflicts that may arise when integrating multiple independent relational database (RDB) schemas into a single multidatabase (MDB) schema. In this paper, we provide a comprehensive classification of techniques for resolving the schematic conflicts that may arise when integrating multiple RDB schemas, or RDB schemas and object-oriented database (OODB) schemas, or multiple OODB schemas. The classification of conflict resolution techniques includes not only those necessary for resolving schematic conflicts identified in the earlier paper, but also additional conflicts that arise when OODBs become part of the databases to be integrated. Most of the conflict resolution techniques discussed in the paper have already been incorporated into SQL/M, a multidatabase language implemented in UniSQL/M, a commercially available multidatabase system from UniSQL, Inc. which integrated SQL-based relational database systems and the UniSQL/X unified relational and object-oriented database system.
C++ objects of types that have virtual functions or virtual base classes contain volatile ('memory') pointers. We call such pointers 'hidden pointers' because they were not specified by the user. If su...
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C++ objects of types that have virtual functions or virtual base classes contain volatile ('memory') pointers. We call such pointers 'hidden pointers' because they were not specified by the user. If such C++ objects are made persistent, then these pointers become invalid across program invocations. We encountered this problem in our implementation of 0++, which is a database language based on C++. O++ extends C++ with the ability to create and access persistent objects. In this paper, we describe the hidden pointers problem in detail and present several solutions to it. Our solutions are elegant in that they do not require modifying the C++ compiler or the semantics of C++. We also discuss another problem that arises because C++ allows base class pointers to point to derived class objects. C++ has emerged as the de facto standard language for software development, and database systems based on C++ have attracted much attention. We hope that the details and techniques presented will be useful to database researchers and to implementors of object-oriented database systems based on C++.
In this tutorial paper, the basic concepts of applying an object-oriented database (OODB) system, called ORION, to the management of a bill of materials (BOM) is addressed. The illustration attempts to demonstrate the...
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In this tutorial paper, the basic concepts of applying an object-oriented database (OODB) system, called ORION, to the management of a bill of materials (BOM) is addressed. The illustration attempts to demonstrate the linkage between the needs of a CAD/CAM environment and the production planning environment with specific reference to the material requirements planning (MRP) system of the future. The structure of a composite object made up of objects is the major consideration of the proposed object-oriented BOM (OOBOM). The concentration is on composite objects in the OOBOM schema evolution, their propagations of changing object instances, and the unique object identity of each manufacturing part. The proposed OOBOM system is rudimentary, and may be embodied by using the Itasca(TM) system, which is a commercial OODB system whose prototype is ORION, or by using the C++ language. In this paper, both viewpoints, ORION and C++, are discussed.
database systems that can efficiently manage complex objects are increasingly needed in many different fields, such as office automation, knowledge processing, CAD/CAM, CASE, etc. A lot of recent complex object databa...
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database systems that can efficiently manage complex objects are increasingly needed in many different fields, such as office automation, knowledge processing, CAD/CAM, CASE, etc. A lot of recent complex objectdatabase systems support the concepts of object identity and object identifier. Following an object identifier to access the referenced object is called navigation operation and is an essential operation in dealing with complex objects. Navigation operation is a difficult operation to implement efficiently since every navigation operation inherently causes one disk access operation. This paper proposes a scheme to notably accelerate the navigation operation among a sea of complex objects, by increasing the effective number of objects in one disk page. The main concept of the presented technique is threefold. The first idea is to store a cached value within a complex object that is referencing another complex object. The second is that when the referenced object is to be updated the update propagation is delayed until the time when the cached value is referenced. The third is to utilize a hashed table on main memory to efficiently validate the consistency between the cached values and the original values.
This paper describes a database capable of supporting a diverse set of power system simulation applications ranging from harmonics and transients analysis to conventional load flow and short-circuit calculations. The ...
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This paper describes a database capable of supporting a diverse set of power system simulation applications ranging from harmonics and transients analysis to conventional load flow and short-circuit calculations. The wide range of applications requires that the data be modeled in a more basic, or lower-level, form than is required for many traditional power systems analysis programs. The need for the database, the design objectives, and evolution of the design are described. A strictly relational database was attempted at first. Difficulties in modeling complex data structures resulted in changing the database to a more object-oriented form. Several of the key data structures are presented as well as typical programming techniques for accessing the database.
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