Critical Success Factors for Implementing a Configuration Management System

Companies must deliver quality products to market in the shortest possible time in order to remain competitive in today’s business environment. One technology tool which is emerging as a key to reducing time to market is configuration management. This paper discusses why configuration management is important and the the critical success factors for the effective implementation of a configuration management system.

Implementing the CAM-I Application Interface Specification With UNIX Interprocess Communication

The CAM-I Application Interface Specification (AIS) allows applications to access a geometric modeler for model analysis using a standardized interface. This is accomplished by linking the source or object codes of the application and modeler together at compile time along with the AIS implementation for the modeler. This methodology requires at least the object code of both programs and results in a single, large executable program dedicated to the use of the specific application and modeler only. By using interprocess communication (IPC) with the AIS, the two programs can remain separate and be used with other modelers and applications rather than only with each other. The approach used in defining the AIS/IPC adaptation issues and developing and testing concepts to address those issues resulted in successfully implementing AIS using the messaging routines of IPC. This allowed an independent application to invoke and interface with an independent geometric modeler and perform analyses on representative models. The implications of the approach used and the implementation of AIS with IPC in engineering are broad. Using a modified form of the AIS/IPC, an application could theoretically interface with a modeler on a remote system far from the host.

Testing CALS Standards for Engineering and Manufacturing Applications

Standards verification in a CALS environment can be a complex and demanding process requiring not only a complete understanding of the standard but also the planned application and software implementation. An area of particular concern is the adequacy of vector or geometry based standards such as IGES to represent engineering and manufacturing applications. In such cases the visual similarity of geometry can be an inadequate test of the validity of a data exchange. Analytically oriented use of the geometry representation of some design and manufacturing applications may require very precise exchange of geometric entities. This paper will focus on testing strategies to provide comprehensive evaluations of vector based geometry standards such as IGES for engineering analysis, design and manufacturing use. The tests will show effective ways to measure whether vendor translators adequately capture key behavior needed in such applications. Results will be illustrated through tests at the Georgia Tech CALS Research Center which includes several different workstations and associated CAD software systems. CALS Class II test suites taken from representative aerospace applications are used to illustrate these concepts. The results show the importance of such testing in the verification of future CALS standards built around the PDES/STEP efforts. Finally the paper will outline the role and importance of an analytic testing facility in a comprehensive academic research program on information technology for engineering and how it influences current and future engineering education.

Information Management to Support Concurrent Engineering Environments

The development of products in large industrial organizations involves numerous engineers from different disciplines working on inter-dependent components of the product with objectives that are sometimes in conflict. The need for overall coordination, consistency, control and integrity of data, design ideas and design rationale is critical. The information generated by each designer must be viewed in the context of information generated by other designers, and the enterprise as a whole. In this paper, we discuss a model of concurrent engineering that focuses on the ability of collaborating designers to proceed independently, co-relate inter-dependencies, utilize existing information (data, knowledge and processes), and negotiate conflicts arising from design inconsistencies. To provide information based support for such environments, we introduce several design schemas to support the concurrent, collaborative and historical aspects of CE environments. The need for a data dictionary that supports these schemas and its different dimensions is also recognized. The dictionary must also provide conceptual centralization of design information relative to the enterprise. This includes data, as well as its definition (meta-data), and must allow the design process to interact with a global enterprise perspective. These discussions lead to a list of research issues that must be addressed by the engineering data management research community.

A Product Data Model for Design Support Using Functional Skeletons

This paper presents a new method called Functional Skeletons and its usage for a product data model for the design process. The Functional Skeletons represent the main functional flows in a product and allow the efficient storage of designs as well as the generation of verified (in respect to their specification) products. The Functional Skeletons can be used as the basis of a new type of product data models.

Environment for Application Software Integration and Execution

The Environment For Application Software Integration and Execution (EASIE) is a methodology and a set of software utility programs developed at the NASA Langley Research Center for coordinating the use of engineering design and analysis computer programs. Under user direction, EASIE controls the execution of independently developed programs and manages the flow of data to and from a common relational data base in order to accomplish design or analysis objectives. The process is highly automated. For example, a utility program generates a DATA DICTIONARY, describing the contents of the data base and the various subsets of data used by the application programs. Other utilities automatically generate FORTRAN or C subroutines to link the application programs with the database or to pre- and post-process the data. EASIE is also “user friendly,” providing “windows” into the data base to view subsets of the data and the means to modify the data at any time A key feature is the degree of independence it provides to the programmer and user from the details of the operating system and Data Base Management System. EASIE has been used successfully in the integration of several design systems at Langley and within the aerospace industry. This paper discusses the application of EASIE to these specific systems, emphasizing the advantages it has provided to both programmers and users. Significant improvements made as a result of these experiences will also be discussed.

The Use of Application Model Validation in Testing a Proposed Standard

From an information system development perspective, logical data modeling techniques have traditionally served in two roles. The first role is as a method of describing the information requirements of an application system. The second role is as a mechanism for integrating the requirements from a number of applications into a single logical and consistent schema so that data can be shared by multiple applications. The Standard for the Exchange of Product Model Data (STEP) project is developing an international standard1 which uses data modeling as the basis for a multi-national and multi-enterprise integration effort. STEP is designed to provide a complete, unambiguous, computer-readable definition of the characteristics of a product throughout its life cycle. STEP product definition specifications are implementation independent, though implementation interface techniques provide the communication mechanisms for applications using file exchanges2 or shared databases. Because of the diversity of applications that are within the scope of STEP, the integration generally causes extensive changes but the changes are justified if all of the information requirements are supported.

The Design of Object-Oriented Software for the Representation of Mechanical Parts

The objective of this paper is to present a design of the software for the representation of a simple mechanical part using object oriented software construction techniques. The object oriented method of software construction is particularly suitable for representing complex mechanical parts, their dimensions and tolerances since modular and reusable software can then be obtained. The focus of this paper is to demonstrate through a simple example the software quality advantages that are obtained when abstract data types are used to describe classes of objects. The notion of inheritance is employed to show how a general software architecture can be designed for mechanical part representation. Finally, the Eiffel language is utilized as a design and specification tool to write the software specifications for the simple example studied. The software specification is developed using the axioms notion of the theory of abstract data types to specify the semantic properties of the object oriented software.

PDES/STEP: A Status Report

This status report provides a current overview of the work that is progressing toward the development of an international Standard for the Exchange of Product model data (STEP). STEP has the potential for revolutionizing the exchange of product definition data. The current state of the art in product data exchange requires knowledge of both the sending and receiving system in order to expect a reliable exchange to occur. The basic premise that STEP is built upon is to support the exchange and sharing of product model data without the need to know the sending or receiving system. The first release of STEP as a Draft International Standard will occur in 1992. The capability of that release will provide a strong basis for system designers and integrators to develop STEP compliant products that can support a significant portion of the product definition data that is exchanged today between and within businesses.

An Automated Database System for Preliminary Spacecraft Design

Spacecraft preliminary design is usually fast-paced and occasionally hectic. Decisions on configuration, propulsion systems, primary structure, cost, safety, reliability, and other disciplines are made almost daily. Keeping the design team informed of the decisions and the reasons for them in a timely fashion is a formidable task — one that is greatly facilitated by an automated database. This paper describes the scope, applications, and benefits of an automated base system that is currently in use on a spacecraft preliminary design project.