Social and psychological aspects of computer-aided design systems

A study was performed among design employees in three large companies to investigate the psychosocial effects of computer-aided design (CAD) work. The study included all technical employees of the departments selected, of whom about two-thirds worked with CAD systems. The results demonstrate that 90% of the CAD users have a positive attitude to CAD-work. No significant differences were found between CAD users and non-CAD users in terms of work load, autonomy, social support, job satisfaction, personal development, or degree of co-operation. Within the group of CAD users, those spending a larger number of weekly working hours with the CAD system reported lower work complexity, lower autonomy of work methods, and less job satisfaction. CAD users with a relatively higher number of years of CAD experience reported a greater work load, fewer CAD difficulties, and lower autonomy of work methods. Among draftspersons and designers, there were no significant differences in work activities between CAD users and non-CAD users.     

Social systems that marginalize the psychological and organizational aspects of information technology

This polemical paper is concerned with identifying the factors which serve to marginalize the psychological and organizational aspects of the development, implementation and use of information technology. Five sets of factors are delineated, those associated with: end-users; suppliers, 'experts' and the development process; management and organizations; research and development; and education and understanding. The analysis points to the presence of a complex, mutually reinforcing set of social systems acting to marginalize psychological and organizational concerns, and helps explain the massive difficulties in achieving change. It also reveals that psychological and organizational expertise tends to be supply-pushed rather than demand-pulled into the community. This may help explain why many working in this field fail to practise the user-centred approaches that we preach.     

Social systems that marginalize the psychological and organizational aspects of information technology

Abstract

This polemical paper is concerned with identifying the factors which serve to marginalize the psychological and organizational aspects of the development, implementation and use of information technology. Five sets of factors are delineated, those associated with: end-users; suppliers, ‘experts’ and the development process; management and organizations; research and development; and education and understanding. The analysis points to the presence of a complex, mutually reinforcing set of social systems acting to marginalize psychological and organizational concerns, and helps explain the massive difficulties in achieving change. It also reveals that psychological and organizational expertise tends to be supply-pushed rather than demand-pulled into the community. This may help explain why many working in this field fail to practise the user-centred approaches that we preach.     

Data structures and DBMS for computer-aided design systems

The structures for the storage of data in CAD systems influence to a large extent the effectiveness of the system. This paper reviews the wide range of data structures and database management systems (DBMS) available for structuring CAD data. Examples of basic data types are drawn from the MODULA-2 language. The relationship between these basic data types, their composite structures and the classical data models (on which many DBMS are based) is discussed, and the limitations of existing DBMS in modelling CAD data highlighted. A set of requirements for CAD database management systems is drawn up and the emerging role of product models (which seek to encapsulate the totality of data elements required to define fully an engineering artefact) is explored.     

Multiobjective insensitive computer-aided design of aerospace control systems

A multiobjective CAD method for aerospace control systems has been developed which can meet requirements on disparate objectives over a set of flight conditions, using constrained minimization algorithms with objective functions in the constraint vector. This paper summarizes results of research on four increasingly sophisticated versions of the method: the basic method, an extension which finds Pareto optimal designs which are well-balanced in all objectives, an extension which finds stochastic-insensitive (SI) designs to minimize the sensitivity to uncertain parameters, and a tradeoff method which designs for a compromise between decreased sensitivity and improved nominal objective values. Examples presented are lateral stability augmentation system (SAS) designs to meet multiple handling qualities requirements for a fighter airplane over a range of flight conditions, and similar SAS designs for several flight conditions of the Shuttle entry vehicle. The method requires strong interaction with experienced designers, who must define the objectives and requirements, choose the design flight conditions and the form of the control systems, adjust parameters in the program to get well-balanced designs, and evaluate the design solutions.     

Development of computer-aided design systems for metal-forming processes

Computer-aided forging die design system FACT and roll pass design system DIAGNO have been developed for immediate use in small- and medium-size metal-forming industries. Some illustrative graphics and printouts of these systems appropriate for process evaluation are presented to describe their capability.     

Color-mapping techniques for computer-aided design and verification of VLSI systems

Color raster-scan displays are often equipped with hardware for color transformation. Because the transformation can be redefined much more quickly than a full image can be computed (in a host) and subsequently displayed, it is preferable when possible to perform image operations by simply changing the mapping. Here an interactive layout system for NMOS VLSI is described which gives immediate feedback in color. Viewing modes are emphasized; opaque and translucent modes are discussed which allow the flexibility required for efficient understanding of the design by the designer. The color table is also used to help the designer detect violations of design rules; design rule violations can be readily detected when the transformation unit is used to highlight overlaps of selected VLSI layers or fringe structures derived from them. These color-mapping methods for man-machine interaction promise to enhance the productivity of the designer considerably, and they point the way to VLSI design systems of the future.     

Knowledge engineering in the computer-aided design of control systems

Abstract: MAID is an expert system for the computer-aided design of control systems. It is developed in conjunction with the successful application of a systematic control system design technique. The design problem has been decomposed into sub-problems, resulting in good modularity of design knowledge. Interactive design and the designer's intuition are emphasized. MAID, which acts as a designer's assistant, was developed using the expert systems development facility provided within a control system design package. The coupling of symbolic and numerical processing was carried out in a natural way.     

A computer-aided design system for microelectromechanical systems(MEMCAD)

The authors describe the MIT microelectromechanical computer-aided design system (MEMCAD), in which selected commercial software packages are linked with specialized database and numerical programs to allow designers to quickly perform both mechanical and electrical analyses of structures either described directly, or derived from the design specification (mask data plus process flow). The system architecture, the various modules, and their present status are described, and present system performance is demonstrated with several examples     

Interactive computer-aided formwork design

While disciplines such as structural analysis are reaping the benefits of computer implementation, temporary works design lags well behind. Some of the reasons given by temporary works designers are that their designs are very practical and depend largely on the designer's experience and engineering judgement. By designing a highly interactive user friendly interface, a comprehensive program that runs on IBM compatibles has been developed. The program can be used to design formwork for walls and soffits using traditional timber and/or proprietary formwork components. The program incorporates many features commonly associated with business oriented software interfaces, placing special emphasis on the ease of use and at the same time allowing users to incorporate their own engineering judgement. The user interface features include the use of bar menus, windows and data entry screens. Formwork design may involve the use of material components from different sources, therefore, it is highly data dependent. Consequently, a database management system (DBMS) is used to manage a database of material properties, costs and other attribute data. Formwork members are designed using a rational approach to BS5975: 1982 and the recommendations of the Concrete Society's book Formwork: A Guide to Good Practice. The program produces design details, a schedule of quantities, a cost comparison between purchased and hired proprietary formwork and a cost estimate.     

A framework for the integration of computer-aided design and computer-aided process planning

This paper gives a procedure for integrating Computer-Aided Design (CAD) and Computer-Aided Process Planning (CAPP) systems, a key step in integrating CAD to Computer-Aided Manufacturing (CAM). The three modules required for this integration are a genetic part definition data structure, a preprocessor, and a postprocessor: all three are discussed in some detail. An evaluation of a prototype demonstration system which successfully integrated IBM's CAD package (CADAM) to the United Technologies Computer Managed Process Planning (CMPP) software is discussed.