The art of simulation modelling

It is the contention of the author that practising the “art” of modelling has been, and always will be, of great importance to the ultimate success of any project employing a simulation approach. Yet very few publications address this aspect of simulation modelling exclusively. This paper is an attempt to focus attention on some of these “softer” issues of simulation modelling. By using the concept of a Simulation Syndrome the paper endeavours to highlight some of these issues and to serve as a reminder to simulation modellers of some aspects of the “art” of modelling that are often taken for granted. “Advice is seldom welcome; and those who want it the most always like it the least” Lord Chesterfield.Die outeur is van mening dat die “kuns” van modellering van groot belang is vir die uiteindelike sukses van enige projek waar gebruik gemaak word van ’n simulasiebenadering. Nietemin bestaan daar weinig publikasies waar hierdie aspek van simulasiemodellering spesifiek aangespreek word. Hierdie artikel is ’n poging om die aandag te vestig op sommige van die “sagter” aspekte van simulasiemodellering en die doelwit word bereik deur gebruik te maak van die konsep van ’n Simulasie-Sindroom. Op hierdie wyse word die gebruikers van simulasiemodellering herinner aan somminge aspekte van die “kuns” van modellering wat dikwels as vanselfsprekend aanvaar word. “Advice is seldom welcome; and those who want it the most always like it the least” Lord Chesterfield.http://sajie.journals.ac.z

Industrial engineering : rooting for roots, hankering for heroes

The “roots” of Industrial Engineering are certainly extensive, diverse and deep. Similarly, there are numerous historical “heroes” that made significant contributions to the development of the Industrial Engineering discipline. For the sake of argument, this article will assume that Industrial Engineering has at least two identifiable main roots, namely Determinism and Stochastism. The article attempts to trace the early history of the stochastic root which is very closely linked to the history of probability and statistics and hence games of chance, gambling and divinity. Therefore, the life and times, contributions and personalities of some of the heroes and villains, champions and sad cases of the stochastic world, will be briefly discussed in a somewhat light-hearted, but not necessarily flippant, manner.Die “wortel en tak” van Bedryfsingenieurswese is sekerlik van groot omvang, van diverse aard en diep gesetel. Verskeie historiese “helde” het betekenisvolle bydraes gemaak tot die ontwikkeling van die Bedryfsingenieurswesevakgebied. Ter wille van betoogvoering sal in hierdie artikel aanvaar word dat Bedryfsingenieurswese uit minstens twee identifiseerbare sub-vakgebiede bestaan naamlik : Die Determinisme en die Stogasme. ’n Poging word aangewend om die vroeë geskiedenis van die stogasme na te speur wat op sy beurt aaneengesnoer is met die geskiedenis van die waarskynlikheidsleer en statistiek en dus toevalspelle, dobbelary en wiggelary. Die lewenswyse, tydsgewrig, bydraes en persoonlikheidseienskappe van ’n aantal helde en skurke, kampioene en prulle van die stogastiese wêreld word kortliks bespreek, op ’n ietwat lighartige maar nie noodwendig ligsinnige wyse.http://sajie.journals.ac.z

Simulation modelling as a tool for performing availability and sensitivity analysis

Simulation modelling is a general purpose tool that may be used to provide decision support in a number of application areas. It may be used to analyze, design or "optimize" manufacturing, materials handling, management, commercial and a wide variety of other systems. This paper will report on the design of a prototype decision support tool, based on a simulation model of a vehicle fleet availability problem. The primary purpose of the model is to serve as a tool for the evaluation of the availability of equipment under different conditions and to perform sensitivity analysis.Simulasiemodellering is 'n algemeendoelige tegniek wat gebruik kan word vir die verskaffing van besluitsteun in 'n aantal toepassingsgebiede. Dit mag gebruik word vir die analise, ontwerp of "optimisering" van vervaardiging-, materiaalhantering-, bestuur-, kommersieIe en 'n wye verskeidenheid ander stelsels. Hierdie referaat doen verslag oor die ontwikkeling van 'n prototipe besluitnemingshulpmiddel wat gebaseer is op 'n simulasiemodel van 'n voertuigvloot beskikbaarheidsprobleem. Die hoofdoelwit van die model is om te dien as 'n hulpmiddel by die evaluasie van die beskikbaarheid van toerusting onder verskillende omstandighede asook vir die uitvoer van sensitiwiteitsanalise.http://sajie.journals.ac.z

Using the Business Engineering approach in the development of a strategic management process for a large corporation: a case study

Most South African organisations were historically part of a closed competitive system with little global competition and a relatively stable economy (Manning: 18, Sunter: 32). Since the political transformation, the globalisation of the world economy, the decline of world economic fundamentals and specific challenges in the South African scenario such as GEAR and employment equity, the whole playingfield has changed. With these changes, new challenges ', appear. A significant challenge for organisations within this scenario is to think, plan and manage strategically. In order to do so, the organisation must understand its relationship with its environment and establish innovative new strategies to manipulate; interact with; and ultimately survive in the environment. The legacy of the past has, in many organisations, implanted an operational short-term focus because the planning horizon was stable. It was sufficient to construct annual plans rather than strategies. These plans were typically internally focused rather than driven by the external environment. Strategic planning in this environment tended to be a form of team building through which the various members of the organisation 's management team discussed and documented the problems of the day. A case study is presented of the development of a strategic management process for a large South African Mining company. The authors believe that the approach is a new and different way of addressing a problem that exists in many organisations - the establishment of a process of strategic thinking, whilst at the same time ensuring that a formal process of strategic planning is followed in order to prompt the management of the organisation for strategic action. The lessons that were drawn from this process are applicable to a larger audience due to the homogenous nature of the management style of a large number of South African organisations.http://sajie.journals.ac.z

Generic building blocks for simulation modelling of stochastic continuous systems

The key objective is to present the generic building blocks of a methodology that can be used to model stochastic continuous systems efficiently. The original simulation model of a real-world system is used as the basis for the development of a generic modelling methodology. The generic building blocks of the methodology are used to construct two new simulation models using two different simulation software packages (Arena and Simul8). The evaluation method, the determination of adequate sample sizes and the verification and validation of the models are discussed. The models and software packages are compared and conclusions are presented.Die hoofdoelwit is om die generiese boublokke van ‘n metodiek voor te hou wat gebruik kan word om stogastiese kontinue stelsels doeltreffend te modelleer. Die oorspronklike simulasiemodel van ‘n werklike-wêreld-stelsel word gebruik as die basis vir die ontwikkeling van ‘n generiese modelleringsmetodiek. Die generiese boublokke van die metodiek word gebruik om twee nuwe simulasiemodelle te konstrueer met twee verskillende simulasiesagtewarepakkette (Arena en Simul8). Die evaluasiemetode, die vasstelling van voldoende monstergroottes en die verifikasie en validering van die modelle word bespreek. Die modelle en sagtewarepakkette word vergelyk en gevolgtrekkings word voorgehou.This paper is a more detailed version of a paper titled: “Generic Modelling of a Stochastic Continuous System” that was presented at the 16th European Simulation Multiconference (ESM’2002) that was held from 3 to 5 June 2002 in Darmstadt, Germany.http://sajie.journals.ac.z

Manufacturing simulators

Simulation modelling has been identified as one of the most powerful techniques available for the analysis and design of complex manufacturing systems. A number of manufacturing simulators have been designed in an effort to make it easier to use the simulation approach in the manufacturing environment. This paper will attempt to describe and evaluate the characteristics of some of the available manufacturing simulators as well as possible ways to alleviate some of the inherent disadvantages. This paper will also report on the preliminary design philosophy and specifications of a manufacturing simulation program generator (FACSIM) presently under development.Simulasiemodellering is een van die mees kragtige tegnieke beskikbaar vir die analise en ontwerp van komplekse vervaardigingstelsels. In 'n poging om die gebruik van simulasiemodellering in die vervaardigingsomgewing te vergemaklik is 'n aantal vervaardigingsimulators ontwikkel. Hierdie artjkel sal poog om die eienskappe van sommige van die beskikbare vervaardigingsimulators te bespreek en te evalueer. Tegnieke wat moontlik gebruik kan word om die effekte van die inherente nadele van simulators te verminder sal bespreek word. Die voorlopige ontwerpfilosofie en -spesifikasie van 'n vervaardigingsimulasie programgenerator (FACSIM), wat tans ontwikkel word, sal ook beskryf word.http://sajie.journals.ac.z

Modelling of a stochastic continuous system

The key objective is to develop a method which can be utilized to model a stochastic continuous system. A system from the "real world" is used as the basis for the simulation modelling technique that is presented. The conceptualization phase indicates that the model has to incorporate stochastic and deterministic elements. A method is developed that utilizes the discrete simulation ability of a stochastic package (ARENA), in conjunction with a deterministic package (FORTRAN), to model the continuous system. (Software packages tend to specialize in either stochastic, or deterministic modelling.) The length of the iteration time interval and adequate sample size are investigated. The method is authenticated by the verification and validation ofthe defined model. Two scenarios are modelled and the results are discussed . Conclusions are presented and strengths and weaknesses of this method are considered and discussed .Presented at the 11th European Simulation Multiconference (ESM'97) in Istanbul. Turkey (1-4 June 1997) and included in the conference proceedings.http://sajie.journals.ac.z

Beyond re-engineering: de-engineering the corporation

This paper addresses the failure of re-engineering to deliver its promise of better organizational performance through radical change. It looks at the change in Hammer and Champy's own perceptions of what re-engineering really is and studies reasons for its failure - the problem of ubiquitous IT, the problem ofprocess integration and re-engineering's radical Marxist connotations. Newton's linear clock-like machine view of the world is seen as part ofthefailure ofre-engineering to deliver and is replaced by a quantum view ofcontinued, evolutionary change. Consequently, the chaos phenomenon is studied, especially with respect to the principle of self-organization. Lastly, the proposition of (evolutionary) de-engineering the organization as clean up after or beyond (revolutionary) re-engineering is discussed following on the principles of chaos theory and the emerging viewpoint ofthe organization as a living entity.http://sajie.journals.ac.z

The application of an engineering based methodology to organisational diversification and refocusing - an overview

An organisation is usually bound to the various life cycles of the industries that it serves. In order to ensure sustainability over the long-term, an organisation needs to align and continuously realign itself with its changing environment. According to Thompson [6] the external environment is defined as the macro system of which an organisation is a part. It is either an integral part of the macro system, or it plays a supportive role in the macro system. Although various leading authors, top business professionals and consulting groups have different opinions regarding the use of diversification and refocusing, these seem to be alternative ways of aligning with the changing environment of the industry if used correctly. This paper will present an overview of an integrated diversification and refocusing methodology that may be used to guide organisational transformation.http://sajie.journals.ac.z

Markovian modelling in business risk analysis

Risk analysis in a business context is largely intangible, allowing limited opportunity for the development of means by which the risk can be more securely assured, and in the long run, appropriately managed. This paper proposes that by means ofMarkovian analysis a basis can be established for the development of appropriate models. From the analysis, differential equations are established to solve into meaningful formulae for the system and solved via numerical methods . The use and development ofthis approach is' further illustrated by means of an example .Risiko-analise, in die besigheidsomgewing, is 'n relatiefwasige vakgebied wat beperkte geleentheid bied vir die ontwikkeling van prosedures waarmee die risiko met groter sekerheid bepaal kan word en oor die langtermyn toepaslik bestuur kan word . In hierdie artikel word voorgestel dat Markovanal ise gebruik kan word om 'n basis te verskafvir die ontwikkeling van bruikbare modelle. Uitgaande van die analise kan differensiaalvergelykings opgestel word waarmee die gedrag van die stelsel beskryfkan word . Hierdie differensiaalvergelyking Ian met behulp van numeriese metodes opgelos word. Die gebruik en ontwikkeling van hierdie metodiek word geillustreer deur ' n voorbeeld.http://sajie.journals.ac.z