An information system, in the form of a local area network (LAN), was designed for a video cassette recorder (VCR) manufacturing environment. This system uses the Ethernet approach, with hardware components satisfying IEEE Standard 802.3. The database component can produce reports, graphs and statistical quality control charts. The network communications component allows message sending, screen capture and remote control of test computers. This system provides management with meaningful information in various forms. In addition, it aids VCR boards troubleshooting by making all board measurements available.
This article examines the development of computer aids within manufacturing industry and proposes an alternative approach to the way we design and the designer's role within manufacturing. A feature-based generative design-by-constraints approach is applied, which requires the designer to specify solutions in terms of manufacturing data, which is captured by means of an interactive simulation of machining processes, in which the constraints of equipment, materials and tools are displayed to the designer. The effect of this approach on the integration of all areas within a manufacturing environment is explored, as is the simultaneous design nature of this approach.
It is frequently necessary to machine a contour which has been defined by discreet co-ordinate information. Traditionally, this had been achieved by contour-fitting procedures such as mathematical, parametric or B-splines. A technique has been established for fitting circular arcs to such data to give smooth curves. This article describes how that technique may be used on a PC to generate numerical control (NC) data. A successful machining exercise is detailed
Presents scheme for developing expert systems in hypertext. Hypertext applications are object-oriented environments, which store information in knowledge-based structures. They offer flexibility and speed in information retrieval problems, and are suitable for filing referenced works in a digitised format. Hypertext is also a convenient means of storing interactive technical documentation on-line. However, the application of hypertext to computer-aided engineering has not been realised. The article is based on experience drawn from an expert system developed in hypertext and used for the complete design and evaluation of squirrel-cage induction motors. The project was carried out in the Department of Electrical Engineering at Imperial College
This article describes the effective use of CAD/CAE in the design and analysis of a rocker arm cover system. Non-linear finite-element analysis (FEA) is used to predict the behaviour of the rocker arm cover and the associated sealing system under applied load. The geometry of the cover, which is relatively complicated, is generated with state-of-the-art commercial software and then transferred to the FEA package. The computer simulation is compared with the experimental results, and the agreement is quite satisfactory
Methods for automated process planning and NC programming are surveyed and classified into generic categories. Aspects of CAPP investigated include part definition methods, reasoning and search techniques used to generate process plans, both Al-based and traditional, and process planning languages. NC programming techniques have been categorised into those based on cell decomposition, volume/delta volume decomposition, sectioning, and geometric reasoning. Methods for simulation and verification of NC programs are also surveyed. The current state of the technology and the advantages and shortcomings of each of the CAPP and NC programming generic methods are also discussed
The finite-element method is used to establish a mathematical model of heat transfer in arc welding. The 800-500°C cooling time (the t8/5 time) of the metal adjacent to the weld junction can be precisely calculated by the model. The quantitative relationships between the welding process parameters, the value of t 8/5, the microstructures and the properties of a welded joint are set up, based on experiential formulae and data. A microcomputer-aided system for selecting the arc-welding process parameters has been developed, based on these relationships. The system is designed to run on an IBM-PC or compatible computer
The tasks of analysing and designing knowledge-based systems (KBS) are put into a structured framework. In order to do this, a structured lifecycle for knowledge-based systems is introduced, as well as some tools that allow both the taking of a structured approach and the production of appropriate structured models of the knowledge domain. The authors look first at the process of KBS design to compare and contrast one of the most commonly used design methods, i.e. prototyping, with a structured design method. Making use of terminology introduced by Yourdon (1989) to characterise system projects, the author shows how the adoption of the more formal structured approach need not lead to any loss of the `freshness' that is claimed as the characteristic of a prototyping approach. The various stages of analysis and design are analysed in order to introduce the tools needed to construct the structured models of the knowledge-based system. A very simple example is used to illustrate the ideas expressed
The purpose of the work described was to explore the utility of the Smalltalk/V object-oriented language in prototyping an application that would form just one module of a potentially much more extensive and complex system, a complete VLSI design system. The author also wanted to investigate issues arising from the fact that the application itself and the development methodology would have to anticipate the integration of a series of processes that would extend both up- and downstream; for example, logical and functional design stages, circuit synthesis and testing etc. Others have applied OOP to logic circuit design and to logic simulation. Here OOP is applied to the physical layout of the mask-level geometrical entities that go to make up the silicon realisation of an IC design. >
Verification that the various parts of an assembly fit together correctly is an important use of CAD systems. This can also extend to mechanism simulation. It can, however, be time-consuming if the CAD system is not sufficiently sophisticated. An alternative is to perform the assembly using separate software based on simpler models of the individual parts. The assembled version can then be transferred to the CAD system, using transformation data and the full models of the parts put together. This article looks at the problem of handling the task of assembling the various parts of an overall design. It is important to check that mating features really do fit together before manufacture takes place. It looks at the case where the CAD capabilities are limited
This article outlines a project that forms part of a Teaching Company Scheme involving the simulation of manufacturing systems. Particular emphasis has been given to the process of developing a simulation model capable of evaluating the operational characteristics of a material handling system operated within a Just-in-Time (JIT) environment. The main objective is to identify operational problems specific to the material handling system which may become apparent due to changes in operational methods under JIT. The complex nature of operations and large amounts of initial data created a set of techniques which can be used in further simulation studies. The Teaching Company programme is between Unisys Ltd., Livingston, and Napier Polytechnic, Edinburgh. This article does not attempt to describe current operating conditions.
Traditionally, CAD systems have been algorithm-based and have only played a passive role in the design process. However, if the full potential of the VLSI processing capability is to be realised, it is necessary to evolve tools that are more active in the design process; so that designs may not only be produced quickly, but also be correct first time. Furthermore, the use of tools that make intelligent decisions about various aspects of a design and are aware of their implications in the physical implementation of the circuit will abstract the engineer from the overall complexity of the design process, allowing him/her to be more creative. The introduction of expert systems techniques into CAD tools is an approach currently being explored to make CAD tools more active. Applications of these techniques to various aspects of the design of VLSI circuits are described
The application of computer modelling can involve considerable savings, with a reduction in costs, time taken to manufacture products and the amount of floor space occupied; thus optimising the process. The article examines the use of computer modelling in a sheet-metal manufacturing process, at DCE Ltd., Leicester, and demonstrates the savings to be made. The modelling package used was Simcon's PC MODEL linked to a database held on LOTUS 123 spreadsheet software
Discusses a knowledge-based expert system IPDOTS implemented for the preliminary design of offshore topside superstructures. This study is an extension of the study, described in an earlier article into using an expert system for the preliminary design of offshore jacket structures see ibid., vol.7, no.1, p.7-11 (1991). This article concentrates on the architecture of IPDOTS and how it can assist in the design of offshore topside superstructures
Describes a CAE package, supplemented by a powerful database handler for storing geotechnical data of any given geo-map for the design, analysis and management both rigid and flexible pavements. Pavement design and analysis are based on the American Association of State Highway and Transportation Officials (AASHTO) guide. The cost and performance of different maintenance strategies on flexible pavements can be undertaken and evaluated. The database is based on a hierarchical data structure which provides speed and flexibility of information access as well as expansibility. The menu-driven package guides the user through the different steps involved in the design, analysis graphs, and maintenance strategies for pavement rehabilitation. Throughout the design stage, the user has the option of using the information stored in the database or relying on their own data. The design and analysis of pavements, complemented by a geotechnical database makes this package a powerful CAE tool for civil engineering pavement designers
The development of integrated computer systems in the fields of architecture, engineering and construction (AEC) requires a viable scheme for data exchange between professional groups. Data exchange capability has two essential components: representation standards and feature extraction. A representation standard is an agreement among AEC professions about a common problem description language. Feature extraction is a process by which a particular professional entity derives a domain specific representation i.e. an interpretation, from a common representation. The roles of standards and feature extraction can be understood in terms of their relation to the overall problem-solving structure. This article presents a communication architecture for integrating AEC design data based on the principle of local interpretation of a low-level graphic exchange language. A prototype implementation is described
