African Journals Online
South African Journal of Industrial Engineering

Volume 13, Issue 1, 2002

Constraint programming and university timetabling
Groves, G.W.Van Wijck, W. 1-12

Abstract: The technology of Constraint Programming is rapidly becoming a popular alternative for solving large-scale industry problems. This paper provides an introduction to Constraint Programming and to Constraint Logic Programming (CLP), an enabler of constraint programming. The use of Constraint Logic Programming is demonstrated by describing a system developed for scheduling university timetables. Timetabling problems have a high degree of algorithmic complexity (they are usually NP-Complete), and share features with scheduling problems encountered in industry. The system allows the declaration of both hard requirements, which must always be satisfied, and soft constraints which need not be satisfied, though this would be an advantage.

Hierdie artikel beskryf 'n familie van probleem-oplossingstegnieke bekend as “Constraint Programming”, wat al hoe meer gebruik word om groot-skaalse industriële probleme op te los. Die nut van hierdie tegnieke word gedemonstreer deur die beskrywing van 'n skeduleringsisteem om die roosters vir 'n universiteit te genereer. Roosterskeduleringsprobleme is in praktiese gevalle NP-volledig en deel baie eienskappe met industriële skeduleringsprobleme. Die sisteem wat hier beskryf word maak gebruik van beide harde beperkings (wat altyd bevredig moet word) en sagte beperkings (bevrediging hiervan is wel voordelig maar dit is opsioneel.)

Optimal training policy for promotion - stochastic models of manpower systems
Yadavalli, V.S.S.Natarajan, R.Udayabhaskaran, S. 13-23

Abstract: In this paper, the optimal planning of manpower training programmes in a manpower system with two grades is discussed. The planning of manpower training within a given organization involves a trade-off between training costs and expected return. These planning problems are examined through models that reflect the random nature of manpower movement in two grades. To be specific, the system consists of two grades, grade 1 and grade 2. Any number of persons in grade 2 can be sent for training and after the completion of training, they will stay in grade 2 and will be given promotion as and when vacancies arise in grade 1. Vacancies arise in grade 1 only by wastage. A person in grade 1 can leave the system with probability p. Vacancies are filled with persons in grade 2 who have completed the training . It is assumed that there is a perfect passing rate and that the sizes of both grades are fixed. Assuming that the planning horizon is finite and is T, the underlying stochastic process is identified as a finite state Markov chain and using dynamic programming, a policy is evolved to determine how many persons should be sent for training at any time k so as to minimize the total expected cost for the entire planning period T.

Six sigma as a total quality management tool
Odendaal, C.E.Claasen, S.J. 25-33

Abstract: The ultimate goal of most companies is to make money and even more money in the future. Part of increasing profits means reducing costs, improving quality and increasing throughput. This paper describes the use of Six Sigma methodologies as a tool in achieving Total Quality Management in the manufacturing environment, with specific emphasis on power transformer manufacturing. The concepts encompassed by Six Sigma are included, their relevance explained and some early results are shared. The measure, analyse, improve and control cycle is the main emphasis of this paper. It is concluded that by adopting Six Sigma as a Total Quality Management tool, company bottom lines are improved.

Improving the effectiveness and image of the building and civil engineering process by using an award point system in the award of contracts
Grobler, K.Pretorius, L.Strauss, A. 35-44

Abstract: One of the main causes leading to the perceived ineffectiveness and poor image of the building and civil engineering process seems to be the fact that clients often use lowest price as the only selection criterion in the award of contracts. One of the main recommendations of the doctoral research thesis of Grobler [1] is the introduction of an award point system that not only compares bidders on price, but also on their previous records of: quality of work, management ability and relations with other role players.

Een van die hoof oorsake wat aanleiding gee tot die persepsie dat die bou-en siviele ingenieursweseproses oneffektief is en `n swak beeld het, is die feit dat kliënte gereeld laagste prys as die enigste maatstaf gebruik in die toekenning van kontrakte. Een van die hoof voorstelle van die doktorale proefskrif van Grobler [1] is die instelling van `n toekenningspuntesisteem wat nie net tenderaars beoordeel op prys nie, maar ook op vorige rekords van: kwaliteit van werk, bestuursvermoë en verhoudinge met ander rolspelers.

Capital investment criterion for bulk electricity transmission infrastructure: a consumption approach
Smith, R.D.Joubert, R.J.O. 45-67

Abstract: The primary technical function of an electric utility company is to supply electrical energy to its customers economically and at acceptable levels of reliability. The aspects of economics and reliability are however, competing constraints, since increased reliability of supply generally requires increased capital investment, which leads to higher prices for electricity. Traditional capital budgeting criteria, such as positive net present value, have been found to inhibit sound economic capital investment decision-making within the bulk electricity transmission environment. It is submitted that the results of this investigation will enable the operators of bulk electricity transmission systems to match the level of investment in reliability related infrastructure, with customers' reliability preferences. To do this it is necessary to incorporate the economic value-of-service reliability to customers into the economic evaluation used by utility planners.

Applying the theory of constraints to increase economic value added: Part 1-Theory
Smith, M.Pretorius, P. 69-80

Abstract: This article, presented in two parts, explains how to apply the Theory of Constraints (TOC) in a business to increase Economic Value Added (EVA). The first part deals with the theory, while the second part deals with the implementation. The goal of a business, the measurements of the goal and the priority of the measurements are discussed. The future reality of a company which implements TOC principles is shown through cause and effect to lead to an increase in EVA. The increase in EVA is caused by an increase in return on investment and a reduction in the cost of capital. The actions the company must take to increase EVA is presented.

Hierdie artikel, aangebied in twee dele, verduidelik hoe om die Teorie van Beperkinge (TVB) in 'n besigheid toe te pas om Ekonomiese Toegevoegde Waarde (ETW) te vermeerder. Die eerste gedeelte verduidelik die teorie, terwyl die tweede gedeelte die toepassing hanteer. Die doel van 'n besigheid, die maatstawwe van die doel en die prioriteit van die maatstawwe word bespreek. Deur middel van oorsaak en effek word gewys dat die toekomstige werklikheid van 'n besigheid wat TVB beginsels toepas lei tot 'n toename in ETW. Die toename in ETW word veroorsaak deur 'n toename in opbrengs op belegging en 'n afname in die koste van kapitaal. Die aksies wat 'n besigheid moet neem om ETW te vermeerder, word genoem.

A review of technology transfer mechanisms
Le Grange, L.I.Buys, A.J. 81-100

Abstract: This paper gives a review of the theory of technology transfer mechanisms. It is intended as an overview for practitioners. Technology transfer is defined and the technology transfer process discussed. Various technology transfer management tools are presented, such as technology reviews, technology space maps, and technology balance sheets. It concludes with the application of the theory in the form of a new proposed model for technology transfer. The aim of the model is to introduce the basic activities involved in a technology transfer project. The model can be used in a formal technology transfer strategy from the early planning stages, through the measuring of progress and output of the project to the post review of the project.

Hierdie artikel gee `n oorsig van tegnologie-oordrag meganismes. Dit word aangebied as `n oorsig vir praktisyns. Tegnologie-oordrag word gedefineer en die tegnologie-oordrag proses word in bespreek. Verskeie tegnologie-oordrag bestuursgereedskap, soos tegnologie oorsigte, tegnologie ruimtekaarte en tegnologie balansstate word voorgehou. Ter afsluiting word die toepassing van die teorie in die vorm van `n nuwe voorgestelde model vir tegnologie-oordrag voorgehou. Die doel van die model is om die basiese aktiwiteite waaruit `n tegnologie-oordrag projek bestaan duidelik na vore te bring. Die model is geskik vir gebruik as deel van `n formele tegnologie-oordrag strategie vanaf die vroeë beplanningsfases, deur die meting van vordering en die uitset van die projek, tot die nabetragting na afloop van die projek.

Technology management in the public health sector: professional view from equipment maintenance experts
Kachieng'a, M.O. 101-119

Abstract: South Africa has tried various strategies to improve access, quality and cost-efficiency in the health care delivery systems. However it is clear that the optimal approach has yet to be found. It has been recognised that health technology is an important element of this transformation, and will continue to play a vital role. It is almost evident that the way health technology is managed in health care institutions directly affects the quality of treatment patients receive. Although strategic importance of technology in health care has been documented widely in scientific literature; technology planning, procurement and management have not received the attention they deserve in the transformation of health care services in the country. The survey discussed in this paper investigated health care equipment maintenance problems and associated technological constraints from point of view of health technology managers, biomedical and clinical engineers. It also provides recommendations for competitive utilisation of technology in the public health sector.

A model for telecommunication technology transfer and diffusion into the rural areas of South Africa
Pieterse, H.L.Pretorius, M.W. 119-129

Abstract: Telecommunication is one of the keys to sustainable economic development in South Africa. Mobile operators are already reaching people in rural areas without roads, rail or a stable power supply. Telecommunication is also a fast moving high-technology field where technology transfer occurs regularly. Technology transfer is however a complex subject where governmental regulations, social and cultural aspects, needs, expectations, aspirations, financial abilities and technological capabilities play their part. Transfer models that neglect these aspects, often cause ineffective utilisation of technology. Technology transfer between two parties at different hierarchical levels of technology, often occur with limited advantages to the lesser-developed party. A transfer model is needed to improve the transfer process. This research attempts to provide such a model and guidelines.

Telekommunikasie is een van die belangrike insette tot voortgesette ekonomiese groei in Suid Afrika. Mobiele telekommunikasieverskaffers voorsien reeds dienste aan mense in afgeleë gebiede sonder paaie, spoornetwerke of stabiele elektrisiteitstoevoer. Telekommunikasie is `n tegnologies gevorderde veld waar ontwikkeling vinnig plaasvind en tegnologie-oordrag algemeen voorkom. Die oordrag van tegnologie is egter `n komplekse onderwerp wat aspekte soos regulatoriese maatstawwe, sosiale- en kulturele aspekte, behoeftes, verwagtinge, aspirasies, finansiële aspekte en tegnologiese vaardighede insluit. Oordragsmodelle wat nie hierdie aspekte in ag neem nie, lei tot sub-optimale aanwending van die tegnologie. Tegnologie-oordrag tussen partye op verskillende vlakke van tegnologiese vermoë vind dikwels plaas, met beperkte voordeel aan die minder-ontwikkelde party. `n Oordragsmodel is nodig om die oordragsproses te verbeter. Hierdie navorsing het dit ten doel om so `n model te verskaf.

High velocity thermal gun for surface preparation and treatment
Gorlach, I.A. 131-143

Abstract: Many surface preparation and treatment processes utilise compressed air to propel particles against surfaces in order to clean and treat them. The effectiveness of the processes depends on the velocity of the particles, which in turn depends on the pressure of the compressed air. This paper describes a thermal gun built on the principles of High Velocity Air Fuel (HVAF) and High Velocity Oxy Fuel (HVOF) processes. The designed apparatus can be used for abrasive blasting, coating of surfaces, cutting of rocks, removing rubber from mining equipment, cleaning of contaminations etc.