Aloysius Cornelio

A tool for integrating conceptual schemas and user views

An interactive tool has been developed to assist database designers and administrators (DDA) in integrating schemas. It collects the information required for integration from a DDA, performs essential bookkeeping, and integrates schemas according to the semantics provided. The authors present the capabilities of this tool by discussing the integration methodology and the user interface of the tool.<<ETX>>

Integration and cataloging of engineering design information

An engineering design database system that consists of a query interface, a knowledge representation structure called the semantic association graph (SAG), and a design store is presented. SAG classifies existing design specifications by exploiting the common capabilities of a set of designs. The SAG generation algorithm computes the subsumption relations among design specifications (if they exist). The creation, evolution, and querying of the SAG structure are presented. The designer simply states the input requirements in the form of a simple declarative query which is mapped into the SAG structure. The system then suggests a set of designs that partially match the input requirements. The designer then takes these suggestions and retrieves the detailed design knowledge from the design store. The resulting scheme resembles KL-ONE, but has additional properties such as node sharing to model overlapping concepts.<<ETX>>

Extending object-oriented concepts to support engineering applications

A presentation is made of a structure-function (S-F) paradigm for representing engineering designs. The S-F paradigm treats structures and functions as first-class objects by modeling the physical configuration of the design as structural objects and the behavior of the design as functional objects. The paradigm supports engineering designs by using the associative knowledge between structures and functions to help in the design process and to support simulation by providing for a run-time interaction between structures and functions. The S-F paradigm would be generally applicable to model the passive and active information in any complex system. It may be implemented as a layer on top of any object-oriented model.<<ETX>>

Modeling physical systems by complex structural objects and complex functional objects

This paper describes the general properties of complex objects in engineering designs. There are two types of complex objects: (i) the complex structural objects which describe the physical composition of the design, and (ii) the complex functional objects which describe the behavior of the design and its components. Data manipulation operations on complex structural objects are governed by a set of structural invariants. Similarly, the validation of functional abstraction is governed by a set of functional invariants. The structure-function interactions are represented by interaction objects that describe a set of mappings. These three object types constitute the Structure-Function paradigm. The S-F paradigm can be used to represent engineering designs and active environments, monitor manufacturing operations and industrial processes, and carry out simulations.

Database support for engineering CAD and simulation

An integrated database architecture is presented to support the diverse requirements of a CAD environment. The resulting CAD system consists of a design representation database, an existing-design database, and a parts catalog database. The design representation database stores and manages designs currently being developed. The existing-design database and the parts catalog database serve as suggestion systems. The first suggestion system helps the designer by recommending an existing design that closely satisfies the input specifications. In the second suggestion system, the user provides an incomplete component specification and the system suggests a set of standard components that fit these descriptions. A structure-function CAD modeling paradigm is used to represent designs, to perform simulations, and to let designs evolve over time. The structural information represents the physical or the logical aspects of the design, whereas the functional information represents the behavioral aspects of the design.<<ETX>>

Using active database techniques for real time engineering applications

An active database model for representing engineering design, simulation and monitoring applications is described. The physical aspects of these applications are modeled by structural objects. The functions of the application are modeled by functional objects. The interaction between structures and functions is modeled by interaction objects. Events relate structures and functions such that any state change will cause the functional model to compute the new consistent state of the application. Ways to model event correlation, event recall, and ways to define schemas for continuous systems are presented. A parallel computing architecture and a set of guidelines on task distributing that make the model applicable to real-time application are discussed.<<ETX>>

A database approach to engineering design by selection

Design processes can be classified based on the nature and frequency of a design problem. Designers possess the knowledge of the structure of design objects, and the techniques needed to perform design. Engineering design objects in general consist of assemblies of components and involve the design of the components through satisfaction of constraints between them. In this paper we propose a formal object-oriented approach to the description of engineering designs, and the management of design objects. The concepts of design objects, primitive design, design constraints and dependencies have been formalized. Factors outside the domain of the target design object determine what technique is used by the designer to solve the design problem. We discuss the representation of design techniques themselves using a graph-based approach and illustrate a methodology for design and its use by a designer. Design objects and design techniques are mapped into the relational model because of its wide acceptance and the current availability of relational database management systems. We point out how this environment may be used for conducting the design process by selection of components.

Applying active database models for simulation

Complex physical systems require the support of data models to define and manipulate the data generated during simulation. These models should have the expressive power to represent the static and temporal relationships among data and they should have the capability to initiate actions to enforce these relationships when the application state is changed. Most commercial databases are passive, i.e., they do not take action or enforce a constraint when the data undergoes a state change. Object oriented database systems have taken the technology one step further by encapsulating operations with the data. In this paper we propose a data model for simulation which builds on object oriented and active database principles to represent physical systems in terms of its structure and function. This model is called the structure-function paradigm, or SF-paradigm for short.

Organizing engineering designs and design techniques

The authors present an approach to organizing engineering designs and design techniques in a database system. This database system stores existing designs and provides a mechanism for capturing the design process in the database. The authors develop the notions of assembly objects and component objects, define the idea of design dependencies among objects and explain dependencies in terms of constraints. They also develop a representation of design techniques, show a representation of design objects, techniques, and dependencies, and present a scenario for performing designs. Dependencies between objects are recognized and treated uniformly as objects in a database. It is pointed out how this environment may be used for conducting the design process by selection of components.<<ETX>>