Showing papers in "Computer-aided Design in 1974"
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TL;DR: The concepts and application of graph theory to practical problems involving networks are discussed and examples are given from digital system design.
Abstract: The concepts and application of graph theory to practical problems involving networks are discussed. Examples are given from digital system design. The paper was presented at a one-day symposium on Networks, organized by the Computer-Aided Design specialist group of the British Computer Society and held on the 18th March 1974.
86 citations
31 citations
TL;DR: A description is given of the BERSAFE computer system together with a set of associated computer programs which enable the thermal and stress analysis of arbitrary structures.
Abstract: A description is given of the BERSAFE computer system together with a set of associated computer programs which enable the thermal and stress analysis of arbitrary structures. The finite element method is used, and particular attention is given to user aids, such as automatic mesh generation and computer plotting of meshes and results.
26 citations
TL;DR: A more flexible version of a proven technique by using a set of end conditions suggested by Nutbourne is presented, of greatest interest to users of inexpensive, computer graphics equipment who are interested in improving passive graphical output.
Abstract: Several approximate methods for cubic spline curve fitting have been developed and successfully used. This paper presents a more flexible version of a proven technique by using a set of end conditions suggested by Nutbourne. The advantages and disadvantages of several techniques are clarified and sample graphical output is given. The results should be of greatest interest to users of inexpensive, computer graphics equipment who are interested in improving passive graphical output.
18 citations
TL;DR: The application of two new algorithms for minimax optimization due to Charalambous and Bandler to the problem of finding the coefficients of a recursive digital filter to meet arbitrary specifications of the magnitude or the group delay characteristics is investigated.
Abstract: The application of two new algorithms for minimax optimization due to Charalambous and Bandler is investigated. The application is to the problem of finding the coefficients of a recursive digital filter to meet arbitrary specifications of the magnitude or the group delay characteristics. Unlike the original minimax algorithm due to Bandler and Charalambous in which a sequence of least p th optimizations as p tends to infinity is taken, the two new algorithms do not require the value of p to do this. Instead, a sequence of least p th optimization problems is constructed with finite values of p in the range 1 . A criterion is given under which the order of the filter can be increased by growing filter sections. A general computer program has been developed, based on the ideas presented.
18 citations
TL;DR: In this paper, the vertical and lateral plane motions and applied loads of a ship in waves are calculated using the SCORES digital computer program, where the ship can be at any heading, relative to the wave direction.
Abstract: : Information necessary for the use of the SCORES digital computer program is given. This program calculates both the vertical and lateral plane motions and applied loads of a ship in waves. Strip theory is used and each ship hull cross-section is assumed to be of Lewis form for the purpose of calculating hydrodynamic forces. The ship can be at any heading, relative to the wave direction. Both regular and irregular wave results can be obtained, including short crested seas (directional wave spectrum). All three primary ship hull loadings are computed, i.e. vertical bending, lateral bending and torsional moments. All the basic equations used in the analysis are given, as well as a description of the overall program structure. The input data requirements and format are specified. Sample input and output are shown. The Appendices include a description of the FORTRAN program organization, together with flowcharts and a complete cross-referenced listing of the source language.
17 citations
TL;DR: This paper describes generally two computer-aided design systems, DRAM and IMP, which have been developed for this design area and discusses some of the program features required for effective computer- aided design.
Abstract: This paper is a perspective on the adaptation of computer techniques as a resource for the design of mechanical dynamic machinery. It describes generally two computer-aided design systems, DRAM and IMP, which have been developed for this design area and discusses some of the program features required for effective computer-aided design.
13 citations
9 citations
TL;DR: In this article, a FORTRAN 4 computer program for calculating critical speeds of rotating shafts is described, which uses continuous integration of the differential equations of beam flexure across different shaft sections.
Abstract: A FORTRAN 4 computer program, written for the IBM DCS 7094/7044 computer, that calculates the critical speeds of rotating shafts is described. The shaft may include bearings, couplings, extra masses (nonshaft mass), and disks for the gyroscopic effect. Shear deflection is also taken into account, and provision is made in the program for sections of the shaft that are tapered. The boundary conditions at the ends of the shaft can be fixed (deflection and slope equal to zero) or free (shear and moment equal to zero). The fixed end condition enables the program to calculate the natural frequencies of cantilever beams. Instead of using the lumped-parameter method, the program uses continuous integration of the differential equations of beam flexure across different shaft sections. The advantages of this method over the usual lumped-parameter method are less data preparation and better approximation of the distribution of the mass of the shaft. A main feature of the program is the nature of the output. The Calcomp plotter is used to produce a drawing of the shaft with superimposed deflection curves at the critical speeds, together with all pertinent information related to the shaft.
8 citations
6 citations
Journal Article•
TL;DR: A method is proposed which allows local responses to be specified by means of a state diagram description of the interactive process which is held on backing-store on the back-up machine and passed to the satellite at run-time under control of the applications program.
Abstract: The problems of providing fast response to user actions in a small satellite graphics processor attached to a timeshared back-up computer are discussed, and a method is proposed which allows local responses to be specified by means of a state diagram description of the interactive process. This description is held on backing-store on the back-up machine and passed to the satellite at run-time under control of the applications program. Examples are given and the advantages of the method discussed.
TL;DR: The currently fashionable method of calculating first order sensitivity coefficients via the analysis of the original circuit and its adjoint network is an inefficient process which should now be abandoned in favour of more efficient direct methods of calculation.
Abstract: The currently fashionable method of calculating first order sensitivity coefficients via the analysis of the original circuit and its adjoint network is an inefficient process which should now be abandoned in favour of more efficient direct methods of calculation. Apart from its greater efficiency, this direct approach would also lead to clearer understanding, by students and non-specialist engineers, of the essential principles involved.
TL;DR: The development of computers in a production environment in the building industry has so far been slow, but it is suggested that developments have reached the stage where there are real economic benefits as mentioned in this paper.
Abstract: The development of computers in a production environment in the building industry has so far been slow, but it is suggested that developments have reached the stage where there are real economic benefits. There are now reasonable prospects of a greatly increased use.
TL;DR: This paper describes the development of CAPS and is illustrated by some practical examples and the main features of the PROTRAN system are also presented.
Abstract: CAPS (Computer Aided Project Study) is a computer based system which has been developed to assist engineers and designers engaged in aircraft project studies. It has a modular organization encompassing a wide range of topics including mass, aerodynamics, performance and cost estimation. The data flow and module execution is controlled by the PROTRAN system which has been specially developed for CAPS but has other potential applications. Jobs are specified in simple statements using the PROTRAN language. People without programming knowledge rapidly become proficient in its use, but Fortran programmers can use all their experience since it is an extension of that language. This paper describes the development of CAPS and is illustrated by some practical examples. The main features of the PROTRAN system are also presented.
TL;DR: In this article, a method for measuring the efficiency of circulation of traffic within buildings has been developed, applicable to buildings for which the traffic flows are known, and a method has also been developed for placing lift banks or escalators so as to maintain an efficient circulation in buildings covering a large ground area.
Abstract: A method for measuring the efficiency of circulation of traffic within buildings has been developed, applicable to buildings for which the traffic flows are known. A method has also been developed for placing lift banks or escalators so as to maintain an efficient circulation in buildings covering a large ground area.
TL;DR: In this article, the use of finite element methods for the design of piston crowns, cylinder liners and exhaust valves is described and a marked correlation exists between predicted and measured results.
Abstract: Computer-aided design techniques are being increasingly used in the development of diesel engines. The paper describes the use of finite element methods for the design of piston crowns, cylinder liners and exhaust valves and it is shown that a marked correlation exists between predicted and measured results. Hence factors such as piston ring groove distortion, exhaust valve temperatures and liner stresses can be readily evaluated at reasonable cost.
TL;DR: In this paper, a method of computer simulation useful for analysis of an axially symmetrical magnetic circuit with exciting coils, magnetic poles, and permanent magnets is presented, and the vector magnetic potential is obtained by the use of the well-known successive over-relaxation method, so that devices having magnetic hysteresis characteristics can be analyzed easily and accurately.
Abstract: This paper presents a method of computer simulation useful for analysis of an axially symmetrical magnetic circuit with exciting coils, magnetic poles, and permanent magnets. The vector magnetic potential is obtained by the use of the well-known successive over-relaxation method, so that devices having magnetic hysteresis characteristics can be analyzed easily and accurately. In this program, the magnetization intensity distribution within the magnet is taken into account. The new computer programming system is applied to a magnetic shielding hollow sphere, a bar magnet, a ring magnet, and a periodic permanent-magnet structure for traveling-wave tubes, and the flux distribution for these magnetic circuits is shown. The results are seen to be in good agreement with theoretical and experimental values.
TL;DR: Efficient and fast techniques are outlined for achieving this analysis of a network, based on the Gauss elimination technique for solving the simultaneous equations describing the system's behaviour, which can form an integral part of the overall c.a.d. problem.
Abstract: An application of computer-aided design is to the design or optimization ofa physical problem which, if not already a network-type problem, can often be mathematically modelled as such. The c.a.d. aspect is, in part, concerned with the analysis of this network. Efficient and fast techniques are outlined for achieving this analysis and examples are given of application. These techniques are based on the Gauss elimination technique for solving the simultaneous equations describing the system's behaviour. These software techniques can form an integral part of the overall c.a.d. problem. The paper was presented at a one-day symposium on Networks, organized by the Computer-Aided Design specialist group of the British Computer Society and held on the 18th March 1974.
TL;DR: The method described is an efficient way of optimizing in the presence of nondifferentiable constraints and is not affected by random noise.
Abstract: In the adaptive control of machine operations, the optimal working conditions are determined by using an online computer unit to adjust the control systems. Previously used self-optimizing strategies either failed or worked very inefficiently in the present of transducer noise or random movement of the response surface about the mean position. The method described is an efficient way of optimizing in the presence of nondifferentiable constraints and is not affected by random noise.
NEC1
TL;DR: In this paper, an integrated circuit layout design system is presented, combining with a combinatorial optimization technique and man/machine interaction, which allows wiring and placement of components to be determined simultaneously.
Abstract: An integrated circuit layout design system is presented. The system is effectively combined with a combinatorial optimization technique and man/machine interaction. This optimization technique allows wiring and placement of components to be determined simultaneously. By means of a c.r.t. display, the layout design of an integrated circuit chip is finally improved.
TL;DR: The design of a successful concert hall continues to be a difficult task, but recent applications of computer model studies combined with new methods of quantifying personal preference and subjective quality promise to make “the acoustics” of future halls more predictable and satisfactory.
Abstract: The design of a successful concert hall continues to be a difficult task. But recent applications of computer model studies combined with new methods of quantifying personal preference and subjective quality promise to make “the acoustics” of future halls more predictable and satisfactory.
TL;DR: In this article, a fine mesh is used to produce more accurate boundary conditions, and the uncoupling transformations also reduce the computer time to about one-tenth of that by other methods.
Abstract: The technique of finite elements has brought about a new era in the field of structural analysis of ship structures. The application of this technique, however, is limited by the cost and capacity of the computer. Straightforward appli- cations of the finite element method to the whole or to a major portion of the ship have so far been inaccurate and too expensive for design purposes. The method presented combines the advantages of the finite element technique and the uncoupling by coordinate transformation. A fine mesh may now be used to produce more accurate boundary conditions. The uncoupling transformations also reduce the computer time to about one-tenth of that by other methods. The critical assumptions and the basic theories have been verified with experimental test results from the tanker "JOHN A. MCCONE." This report discusses three computer programs; one for the longitudinal strength analysis, one for transverse strength analysis, and one for the local stability check of the structure. The programs themselves appear in subsequent reports.