Extending Database Management Systems for Engineering Applications

During the design of a manufactured component, large amounts of information pertaining to all aspects of the design must be stored, accessed, and operated upon. A database management system (DBMS), composed of a central repository of data and the associated software for controlling accesses to it and operations on it, provides one way to uniformly store, manage, and use this information. This paper presents a framework for an extension to relational database management systems that combines a set of engineering constraints with a database of engineering data items. The representation requires a database that is able to store all of the data normally associated with engineering design as well as the constraints imposed upon the engineering design process. A powerful and flexible constraint processing system is needed to adequately ensure that engineering data conforms to the limitations imposed upon it by the design process. Such a system must be capable of allowing constraints to be invoked at a variety of times, and provide numerous options for the user when violations are detected. This paper introduces a concept called structured constraints that integrates state- of-the-art advances in DBMSs and current research in engineering constraint processing to further enhance CAD system capabilities. It discusses the extensions to relational database theory that are needed to achieve such a constraint handling capability for mechanical engineering applications. The goal sought is a managed repository of data supporting interfaces to a wide variety of application programs and supporting processing capabilities for maintaining data integrity by incorporating engineering constraints. The Structured Constraint model is a general method for classifying semantic integrity constraints. It is based on the structure of the relational model and is therefore independent of any particular query language. In addition, it is a formalism that possesses conceptual clarity and generality which make it useful for representing and communicating arbitrary constraints. The key contribution of this formalism is its basis for a completely definable implementation of an engineering integrity syste

Relational Database Modeling of Building Design Data

This paper discusses the use of a relational database for representing the data gathered and derived during the building design process. In doing so, it considers the complexity of the relationships among a structure's topology, geometry, and attributes, and the critical requirements they impose on the development of a building design database. In the broad arena of computer-aided design, relational database management systems are establishing themselves as useful engineering tools. This is occurring at a time when engineers and architects are moving toward centralized and integrated databases of design information. In such a database, information is directly and readily available to all members of the design team, allowing them to work concurrently on an accurate representation of a wide variety of engineering design data. This paper presents the use of a relational database to model building design data and shows that the relationships among topology, geometry, and attributes can be successfully modeled relationally. The feasibility of interaction between engineering applications programs and the database is also indicated. Although the paper concentrates on structural design data for buildings, the relational model can also be used to represent the data of other engineering design disciplines as well as the data for other structures, assemblies, systems, and processe

Expert Systems and Engineering Design Knowledge

 Of all the contributions of artificial intelligence (AI), expert systems show some of the most significant promise for engineering applications. An expert system provides a framework for acquiring, representing, and using knowledge about a particular application's domain. The role of knowledge in engineering design merits closer attention so that AI-oriented computer-aided engineering (CAE) systems can be developed and maintained systematically. Because'knowledge'in engineering applications is loosely defined, it is necessary to identify knowledge types and the correlations between them before widespread engineering design applications can be achieved. The types of domain knowledge, facts, procedures, judgments, and control, differ from the classes of that knowledge, creative, innovative, and routine. Feasible engineering tasks for expert systems can be determined based on these types and classes of knowledge. Prototype expert systems have been developed for civil engineering applications to assist with interpretation, design, planning, diagnosis, control, and other engineering system functions. A number of these are described herein. Interpretive tasks require reasoning about a task in light of the knowledge available, while generative tasks create potential solutions to be tested against constraints. Only after classifying the domain by type and level can the engineer select an appropriate knowledge-engineering tool for the domain being considered. The critical features to be weighed after problem classification are knowledge representation techniques, control strategies, interface requirements, compatibility with traditional systems, and economic considerations. After considering all of these factors in the selection of the expert system took, the engineer can then proceed with the acquisition of knowledge and the construction and use of the expert syste

Natural Language Prototypes for Analyzing Design Standards

CADLINE has abstract only. This paper addresses the use of natural language processing for acquiring, processing, and representing knowledge from design standards. A standard is a set of provisions providing principles, models, rules, limits, and particulars that are established by some authority for some purpose. In their textual form as written documents, design standards cannot directly be used in computer-aided design (CAD) systems. This paper demonstrates how standards can be transformed, using natural language processing techniques, from their textual form to alternative representations that more readily lend themselves to use in computer-aided design systems, supporting a variety of design applications. The language being transformed is the Building Officials and Code Administrators Building Code, one set of requirements that govern the design of buildings. Prototype computer subsystems have been developed that transform natural language sentences to case-grammar format and finally to subject-relationship- object triplets. The three prototypes that achieve these transformations are described: a parser, a semantic analyzer, and a query system. During one processing cycle, the system identifies that data items in a provision and the relationships between the data items. It also interacts with the user to add new data items to its knowledge bases, to verify data items found, and to add to its vocabulary. Alternatively, it responds to natural-language questions about the contents of the standard by identifying the relevant provisions within the standards. Processing formal documents requires knowledge about vocabulary, word-order, time, semantics, reference, and discourse. Despite the relative clarity of formal writing as it occurs in standards, the difficulties of implied responsibility, multiple meanings, and implied data items remain. A long-term research program at North Carolina State University has been defined that builds on these prototypes to further investigate knowledge acquisition and representation for standard

Role of Database Management Systems in Structural Engineering

Presented at International Association of Bridge and Structural Engineers Symposium on Informatics in Structural Engineering. (1982: Bergamo, Italy). The future integration of structural engineering application programs will depend critically on integrated databases which provide access to information in essentially arbitrary sequences, and which automatically perform a large portion of integrity checking on the data. One source of such design databases are the database management systems (DBMS) evolving from management applications. The paper surveys such systems and presents some extensions neede

CDIS: an Engineering Constraint Definition and Integrity Enforcement System for Relational Databases

Database management systems (DBMS) are an essential component of the computer integrated manufacturing (CIM) environment. A database management system provides a powerful functionality for the storage, management, and use of engineering data. It is lacking, however, in its ability to deal with engineering constraints. In the past, constraint checking was performed by application programs. More recently DBMS's have been incorporating into their structure specifications for enforcing a limited set of integrity constraints and the mechanisms for invoking them automatically. To ensure the correctness of engineering data, an effective constraint management capability must be incorporated into any proposed engineering DBMS. This paper demonstrates how this can be done, proposes a systematic way to classify constraints so that integrity can be maintained efficiently, and discusses a prototype called CDIS which implements the concepts. This paper uses the relational database model to represent both engineering data and engineering constraints. Data integrity is defined and its enforcement through the use of engineering constraints is described. Existing methods for handling constraints are discussed. A new model that enables the engineer to associate design constraints with a relational database is presented and an example is given that demonstrates the model. Extensions to a DBMS to implement the concepts presented are described. No currently available DBMS provides the much needed capabilities proposed her

Spike: a Generic Design Standards Processing Expert System

Standards, codes, and specifications play an important role in the design of buildings, bridges, and other engineering systems. A design configuration must be checked against all standards to ensure that it is acceptable. This process of design conformance checking using standards is often very tedious. The successful automation of conformance checking is one of the components of a comprehensive computer-aided design system. In that past, standards were interpreted and converted into application programs written in procedural programming languages such as FORTRAN. This approach is extremely inflexible and often error-prone. To support a fully automated computer-aided design system, standards must be incorporated into the design process in a more generic and flexible manner. This paper investigates the feasibility of alternatively casting standards in a form suitable for processing in a knowledge-based expert system environment. The emergence of expert systems from artificial intelligence research has provided a technology that readily lends itself to the automation of design standards. Knowledge-based expert systems have become a powerful tool in tackling domains like design where some of the problem-solving knowledge is diverse and ill-structured. Using an expert system tool, a standard can be represented and processed independent of a CAD application program. Two prototype standards processing systems utilizing the production system approach have been constructed and are presented herein. Although the obvious direct translation casting the provisions of a standard as rules in a production system has its advantages, a more generic and flexible representation scheme is proposed herein. The approach advocated in this paper is to represent standards as databases of facts which can be readily and generically processed by an expert system. The database representation is derived from a unified view of standards obtained by using the standards modelling tools proposed by previous researchers in this field during the past decade. Building on this existing technology resulted in a knowledge- based standards processing architecture which is generic, modular, and flexible. An implementation of this architecture is presented and describe

Design Specification Representation and Analysis

The conventional structures of decision tables, information networks, and outlines define the current methodology for the representation and use of design specifications. This paper explores the relationships at the interfaces between these three representational tools. New analysis strategies are presented that provide flexibility at the lower boundary of the information network by converting decision tables to subnetworks within the information network and by compressing multiple subtables into larger tables representing higher- level nodes in the network. Both generation and compression of the information network provide flexibility in organizing a specification. The ability to both generate and compress nodes and subnodes establishes a mean of representing all the relations among the data items of a specification and gives one more direct control over the level of detail of the information network. As a direct consequence of the ability to generate new nodes, new classifiers can be progressively attached to the nodes of the subnetwork, as well as to the nodes in the information network. As a result, specification requirements are more logically identified by the outline and requirements and data items which were previously hidden within decision table conditions and actions are now directly accessible from the outline. Conversely, items inconsequential to the outline can be compressed into nodes and removed from the outline. A computer program is presented that implements these network transformations. The program accurately represents the interface between the network and the decision tabl