computerized fabrication of photomasks for thin-film hybrid microcircuits. The amount of data required for specifying a photomask is kept to a minimum and in addition the techniques expedite the preparation of artwork for such masks. The system is suitable for use with both the Gerber and the CalComp 718 plotters. A CDC6600 is currently used for running the Fortran programs which, with overlays, requires 65 000 octal words of core store.
Walter, N . A . 74.35 'Circuit optimization techniques using a computer', Admiralty Surface Weapons Est., Portsmouth, Hants, UK (October 1972) 70pp The report considers the methods of circuit optimization and compares the advantages and disadvantages of using a computer. One of the most important effects on equipment reliability is accurate design and tolerancing of circuits. The use o f the simplest circuit with adequate performance and tolerancing helps achieve this reliability. Tolerancing can be achieved using Monte Carlo techniques, but some means of circuit optimization is desirable. Williams, S. and Smith, I . R . 74.36 'Fast digital computation of 3-phase thyristor bridge circuits', Proc. Inst. Elect. Eng., Vol 120, No 7 (July 1973) pp 7 9 1 795 The paper describes a computer program, using a tensor analysis method, based on Kron, for the analysis of thyristor circuits under both normal and abnormal conditions. Considerable savings in computer time accrue by the use of a technique for automatically determining a step-length which ensures accuracy and stability of the adopted Runge-Kulta-Merson model. This approach can be extended to the analysis of more complex thyristor networks. The author supports the theory with typical experimental results. The program is written in Egtran for running on a KDF9.
General Bonney, M. C. and Schofieid, N . A . 74.37 'NULISP - A computer-aided design system', Work Study and Manage. Serv., Vol 17, No 9 (September 1973) pp 6 1 6 633 F~kazawa, Y. and Ishilmwa, Y. 74.38 'CADS (Conversational Anaiyser and Drafting s y s t e m ) d e v e l o p e d by IHI' IHI Eng. Rev., Vol 6, No 1 (March 1973), pp 2 5 - 3 7 A standardization technique and automatic piping program have been developed at IHI for the rationalization o f design work and pattern processing. The savings expected from this rationalization are in manpower, reduction of design schedule and integration of design work throughout n.c. engineering. The requirements could not be satisfied f r o m both practical and economic viewpoints. The paper on CADS mainly describes piping design but it can be applied to other fields, for instance, ships, cars and chemical plants. it is a pattern processing system comprising a minicomputer equipped with additional storage, a pencil type input device and high speed automatic drafting equipment.
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Hoare, C. A . R . 74.39 'Computer programming as an engineering discipline', Electron. and Power, Vol 19, No 14 (August 1973) pp 3 1 6 - 3 2 0
listed together with a description and a schematic of the program. A calculation printout is given together with the advantages of using the proposed method.
McKinlay, J . T . 74.40 'Two NEL papers presented at International conferences on man-machine interaction and computer aided design' National Engineering Laboratory, East Kilbride, Glasgow, UK (August 1972), 20 pp Two papers organized by the lEE. They are; 'Further conversational techniques developed for remote access c.a.d.' and 'Demand time V batch processing in the engineering design field'.
Fearn, R.W. 74.45 'Computer programs for ventilated buildings' Heating and Ventilating Eng., Vol 47, No 553 (August 1973) pp 57--60 The author describes an Algol program and deals with the prediction of internal summertime temperatures in rectangular rooms. The effect o f various design changes can be rapidly assessed. The optimum design for limiting internal temperature can then be determined. The program is particularly useful for open plan offices, ventilated either naturally or mechanically.
Penn, R. F. and Davies, D . G . 74.41 'SYTLYN - A program for sight line calculation', Applied Ergonomics, Vol 4, No 1 (March 1973) pp 34--43 The problem considered is that of visibility in a steelworks. The siting of work stations permitting operatives a good view of the machine they control, is a major problem. The SYTLYN program was developed to draw on an incremental plotter a view of the line from any point. The drawings produced were in a form that gave a 360 ° view. The program's advantages and limitations are compared with the use o f manual techniques, together with a discussion of the specification of the shape of objects and interpretation of the plots. Rogers, P.H. 74.42 'SHIP - Simplified Heimholtz-lntegral Program. A fast compact program for calculating the acoustic radiation and radiation impedance for free flooded-ring and finitecircular-cylinder sources.' Naval Research Laboratory, Acoustics Division, Washington, USA. NRL-REP-T240 (June 1972), 6 4 p p , 10 ref. A finite element method based on a onedimensional version of the surface Helmholtz integral equation is used. Axial symmetry is assumed in all cases. Van Dam, A. 74.43 'Some implementation issues relating to datastructures for interactive graphics' Int. J. Comput. Info. Sci., Vol 1, No 4 (December 1972) pp 2 8 7 - 3 1 4 A tutorial paper relating the datastructure and the rest of an interactive graphics system. The distinction between datastructures and storage structures is made together with the problem of datastructure segmentation. A typical graphical application is given, such as a three-dimensional pipe design program and an analysis o f various trade-off decisions. Various highlevel datastructure specification languages are discussed.
Heating, Ventilating and Lighting Brendel, T. and Giittler, G. 74.44 'Computer calculation o f cooling load and amount of heating needed', Gesundbing, Voi 94, No 1 (January 1973) pp 1 - 7 (in German) A Fortran 4 program is presented for calculating the heating and cooling loads of airconditioning installations in buildings. Data collated for compiling the program is
Fitzgerald, D. 74.46 'The computer in the HEVAC industry', Steam Heat. Eng., Vol 42, No 493 (December 1972) pp 1 8 - 2 1 The likely increase in use of the computer in the HEVAC industry in the next few years is considered. Specific applications are described, namely; pipe sizing, air conditioning loads and program organization. Great scope for application in district heating is seen.
O'Connor, L. 74.47 'Computerized pipe-sizing of HWS and CWS networks', Building Services Eng., Vol 41 (May 1973) pp 36--44 A computer program is presented for dimensioning pipes for hot and cold water supply systems. The demand-unit method of flow quantity calculation is used together with the Colebrook-White equation for determining pressure losses as used in the IHVE guide.
Mechanical engineering F a w k e , A. J., S a r a v a n a m u t t o o , H. J. H.
and Holmes, M. 74.48 'Experimental verification o f a digital computer simulation method for predicting gas turbine dynamic behaviour'. Proc. Inst. Mech. Eng., Vol 186, 27/72, pp 3 2 3 - 3 2 9 The dynamic behaviour of an engine may be modelled by describing it by a set o f algebraic and differential equations. A computer programmed to provide a continuous solution to these equations simulates the behaviour of the real engine. This paper describes a method for simulating the transient response o f a gas turbine engine using a digital computer. The simulation technique was validated by comparing predicted transients with a wide range o f engine transients carried out on a fully instrumented twinspool turbojet engine. Kovarik, M.
74.49 'Constrained optimization in the design of duct-work' Fifth Australian Comput. Conf., Brisbane, 1973 The paper discusses the design o f economically optimal system of ducts for supply of air as a problem of constrained optimization. Cost criterion, quantities of material used in the construction, value of occupied space and the cost of energy dissipated in the system are all considered.
COMPUTER AIDED DESIGN