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Two interpolatory cubic splines
Software - Practice and h'xperience Vol 5 No 2 (April-June 1975) pp 115-122 Two algorithms are described for solving the windowing problem in computer graphics. The algorithms described are the midpoint algorithm developed by Sproull and Sutherland and the other is designed for use in the IMP interactive mask design program. Implementations have been made on two minicomputer systems, the PDP-I 1 and the PDP-9, and the algorithms are compared for size and execution times. Kershaw, D. 75.76 'Two interpolatory cubic splines' J of the lnst of Matb. and Its Applications Vol 11 No 3 (June 1973) pp 329-333 Two interpolatory cubic splines are developed which have more favourable con-
vergence properties than the natural one, but which require no additional information. Using as a basis, three preliminary lemmas, the third-order cubic spline is a direct consequence of Hcrmite's two-polnt interpolation formula, the author gives a clear definition and motivation for the two interpolatory cubic splines. Misra, K.B.
7.5.77
'Reliability optimization through sequential simplex search' lntJ. of Control Vol 18 No 1 (July 1973) pp 173-183 The author considers a reliability design problem in which it is desired to find the number of system components of known reliability, weight, and cost at each stage of a system such that overall reliability is maxi-
mized while keeping total system weight and cost within specified bounds. Stoneman, P.
75.78
'Effect of computerization on the demand for labour in the UK' Warwick Univ., Economics Dept, UK 19pp, 15ref. (1974) Presents the results of an exercise, based on some tentative estimates of labour saving in computer use and construction, designed to illustrate how the effects of technological change ought to be considered, not only in terms of comparative statics but also in terms of the effects during the process of change technique, that is, along the transition path. The study concentrates on demand for labour aspects because these can be most readily observed.
Books and Publications Computer-aided lay-planning and cutting for knitted fabrics H A T R A , Research Centre for Knitting, Dyeing and Making-up of Knitted Textiles, Nottingham, UK. 37 pp Special publication 13, (1974) £5.00 This publication, the proceedings of a H A T R A conference of the same title, consists of seven papers from people concerned with the a u t o m a t i o n of clothing production. It is a b o u t the process of lay-planning different size pattern pieces for garments and numerical control cloth cutters in the production process. Lay-planning by computer - efficiently planning the organization of pattern shapes and automated cutting from EDP systems are discussed. The first paper, by G. M. Coles, HATRA, acts as an i n t r o d u c t i o n and gives a breakdown of the clothing m a n u f a c t u r i n g process and makes comparisons between this and other automated industries. Additional system uses are m e n t i o n e d such as fully a u t o m a t e d lay-planning (at present this utilizes interactive graphics) and integrated m a n a g e m e n t systems. The second, seventh and eighth papers by L. Abrahams, H. T. Helfct and R. A. Payn, present users' descriptions and opinions of current systems. These describe system advantages such as consistent and grading accuracy, efficient data access and use and prospectivc user pitfalls. F u r t h e r advantages m e n t i o n e d include lay-planning w i t h o u t patterns, thus eradicating the
Volume 7
Number 3
July 1975
need to initially digitize basic pattern shapes and general waste reduction through online calculation of laymaking efficiency. Production costing is also seen to be a useful system facility The experience of planning for and introducing these systems to c o m p a n y production areas, is discussed. Production and personnel organizational changes through system introduction is referred to with regard to production planning and management decision making. Specific references are made to each c o m p a n y ' s experience in the specification patterns for input, their efficient online use and n.c. data conversion. Longer-term advantages, such as improved garment fit, design and product consistency through rapid responses to fashion demands and easier alteration and access of pattern information is m e n t i o n e d with specific reference to the alteration of the c o m p a n y ' s grading rules by a fashion designer (c.a.&?). The third paper by D. Koener, is a review of logic solutions for economics and scheduling produced by IBM. This has specific reference to cut-scheduling within the total production process and lists relevant production terminology. IBM cut planning solutions are describcd by matrices with size and production limitation combinations. Optim u m solutions for cutting can be computed by IBM programs. The fourth paper b y A. A. Fousoul, describes the Gerberutter system 90, an n.c. knife cutting system. It is stated that control is off- or online and that a vacuum system for cloth compression is included. The system
operation is described and an illustration is included. The fifth paper, b y H. R. Whittle, describes a laser cutting system developed by the UKAEA Culham Laboratory. The development of industrial laser cutting systems is reviewed and a description of the requirements of a cloth cutting system specified. The Culham machine is illustrated showing a fixed position laser and work table and a moveable reflecting mirror. This system and a controller is described and conclusions are drawn on the use of n.c. lasers cutting cloth. This publication reflects the developing (and not finalized) state-of-the-art. As such, it presents a realistic overall picture of most value to prospective users of a u t o m a t e d clothing production system users.
R. N..lerrard Re.~earch Fellow Textile Research Unit, Royal College o f Art, London
Basic questions of design theory Edited by William R. Spillers, North llolland/A merican Elsevier, at 90 Dfl (about £15.00) Like m a n y other books relevant to c.a.d., this is a collection of papers delivered at a conference. It forms a very formidable collection too, and one suspects that the topics and speakers may have been selected with the eventual book very much in mind.
207
vergence properties than the natural one, but which require no additional information. Using as a basis, three preliminary lemmas, the third-order cubic spline is a direct consequence of Hcrmite's two-polnt interpolation formula, the author gives a clear definition and motivation for the two interpolatory cubic splines. Misra, K.B.
7.5.77
'Reliability optimization through sequential simplex search' lntJ. of Control Vol 18 No 1 (July 1973) pp 173-183 The author considers a reliability design problem in which it is desired to find the number of system components of known reliability, weight, and cost at each stage of a system such that overall reliability is maxi-
mized while keeping total system weight and cost within specified bounds. Stoneman, P.
75.78
'Effect of computerization on the demand for labour in the UK' Warwick Univ., Economics Dept, UK 19pp, 15ref. (1974) Presents the results of an exercise, based on some tentative estimates of labour saving in computer use and construction, designed to illustrate how the effects of technological change ought to be considered, not only in terms of comparative statics but also in terms of the effects during the process of change technique, that is, along the transition path. The study concentrates on demand for labour aspects because these can be most readily observed.
Books and Publications Computer-aided lay-planning and cutting for knitted fabrics H A T R A , Research Centre for Knitting, Dyeing and Making-up of Knitted Textiles, Nottingham, UK. 37 pp Special publication 13, (1974) £5.00 This publication, the proceedings of a H A T R A conference of the same title, consists of seven papers from people concerned with the a u t o m a t i o n of clothing production. It is a b o u t the process of lay-planning different size pattern pieces for garments and numerical control cloth cutters in the production process. Lay-planning by computer - efficiently planning the organization of pattern shapes and automated cutting from EDP systems are discussed. The first paper, by G. M. Coles, HATRA, acts as an i n t r o d u c t i o n and gives a breakdown of the clothing m a n u f a c t u r i n g process and makes comparisons between this and other automated industries. Additional system uses are m e n t i o n e d such as fully a u t o m a t e d lay-planning (at present this utilizes interactive graphics) and integrated m a n a g e m e n t systems. The second, seventh and eighth papers by L. Abrahams, H. T. Helfct and R. A. Payn, present users' descriptions and opinions of current systems. These describe system advantages such as consistent and grading accuracy, efficient data access and use and prospectivc user pitfalls. F u r t h e r advantages m e n t i o n e d include lay-planning w i t h o u t patterns, thus eradicating the
Volume 7
Number 3
July 1975
need to initially digitize basic pattern shapes and general waste reduction through online calculation of laymaking efficiency. Production costing is also seen to be a useful system facility The experience of planning for and introducing these systems to c o m p a n y production areas, is discussed. Production and personnel organizational changes through system introduction is referred to with regard to production planning and management decision making. Specific references are made to each c o m p a n y ' s experience in the specification patterns for input, their efficient online use and n.c. data conversion. Longer-term advantages, such as improved garment fit, design and product consistency through rapid responses to fashion demands and easier alteration and access of pattern information is m e n t i o n e d with specific reference to the alteration of the c o m p a n y ' s grading rules by a fashion designer (c.a.&?). The third paper by D. Koener, is a review of logic solutions for economics and scheduling produced by IBM. This has specific reference to cut-scheduling within the total production process and lists relevant production terminology. IBM cut planning solutions are describcd by matrices with size and production limitation combinations. Optim u m solutions for cutting can be computed by IBM programs. The fourth paper b y A. A. Fousoul, describes the Gerberutter system 90, an n.c. knife cutting system. It is stated that control is off- or online and that a vacuum system for cloth compression is included. The system
operation is described and an illustration is included. The fifth paper, b y H. R. Whittle, describes a laser cutting system developed by the UKAEA Culham Laboratory. The development of industrial laser cutting systems is reviewed and a description of the requirements of a cloth cutting system specified. The Culham machine is illustrated showing a fixed position laser and work table and a moveable reflecting mirror. This system and a controller is described and conclusions are drawn on the use of n.c. lasers cutting cloth. This publication reflects the developing (and not finalized) state-of-the-art. As such, it presents a realistic overall picture of most value to prospective users of a u t o m a t e d clothing production system users.
R. N..lerrard Re.~earch Fellow Textile Research Unit, Royal College o f Art, London
Basic questions of design theory Edited by William R. Spillers, North llolland/A merican Elsevier, at 90 Dfl (about £15.00) Like m a n y other books relevant to c.a.d., this is a collection of papers delivered at a conference. It forms a very formidable collection too, and one suspects that the topics and speakers may have been selected with the eventual book very much in mind.
207