Scielo RSS <![CDATA[South African Journal of Industrial Engineering]]> http://www.scielo.org.za/rss.php?pid=2224-789020160004&lang=en vol. 27 num. 4 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Note from the editor</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Probability management and the flaw-of-averages</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400002&lng=en&nrm=iso&tlng=en Uncertainty is ever-present and is an integral part of life. Recognising the existence of uncertainty and its possible effects on decision-making may be important for the profitability, financial success, or even survival of an organisation. A relatively new discipline, - known as probability management, - has recently emerged as part of operations research/management science. This paper will attempt to provide a brief introduction to the concepts of probability management and the motivation behind its development. One of the major driving forces resulting in this development is the phenomenon known as the 'flaw-of-averages'. The flaw-of-averages has important consequences in industrial engineering, financial, business, and economic models. The classic newsvendor problem will be used as an illustrative example. However, the main purpose of this paper is to discuss the most important characteristics of the flaw-of-averages. It will investigate and attempt to quantify some of the generic factors that may have an influence on the existence and severity of the flaw-of-averages and its expected consequences. Various models will be developed, and experiments will be conducted using Microsoft Excel as a modelling tool and an experimental approach based on Monte Carlo simulation modelling.<hr/>Onsekerheid is altyd teenwoordig, en is 'n integrale deel van die lewe. Die herkenning van die bestaan van onsekerheid en die moontlike gevolge vir besluitneming mag belangrik wees vir die winsgewendheid, finansiële sukses en selfs die voortbestaan van 'n organisasie. 'n Relatief nuwe konsep het onlangs verskyn as deel van operasionele navorsing / bestuurswetenskap bekend as waarskynlik-heidsbestuur. Hierdie artikel sal poog om 'n kort inleiding te verskaf tot die konsep van waarskynlikheidsbestuur en die motivering agter die ontwikkeling daarvan. Een van die belangrike dryfvere agter hierdie ontwkkeling is die fenomeen bekend as die 'gemors-vangemiddeldes'. Die gemors-van-gemiddeldes het belangrike gevolge in bedryfsingenieurswese, finansiële, ekonomiese en besigheids-modelle. Die klassieke koerantverkoperprobleem sal as n illustratiewe voorbeeld gebruik word. Die hoofdoelwit van hierdie publikasie is egter om die mees belangrike eienskappe van die gemors-van-gemiddeldes te bespreek. Dit sal sommige van die belangrikste generiese faktore wat 'n invloed mag hê op die bestaan en die erns van die gemors-van-gemiddeldes ondersoek, en poog om die verwagte gevolge daarvan te kwantifiseer. Verskeie modelle sal ontwikkel word, en eksperimente sal uitgevoer word deur gebruik te maak van Microsoft Excel en 'n eksperimentele benadering gebaseer op Monte Carlo simulasie modellering. <![CDATA[<b>Knowledge- sharing within the project-based organisation: a knowledge-pull framework</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400003&lng=en&nrm=iso&tlng=en This paper examines mechanisms to use lessons learned on individual projects within an organisation. A Delphi study highlighted the organisation's responsibility for incorporating knowledge from projects into a project management methodology. Knowledge from a project should be transferred through a centralised knowledge management function that should evaluate codified knowledge within the context in which it was generated, determine how the knowledge should be used, and maintain the explicit knowledge database and the knowledge flow process. Based on a literature review, structured interviews, archived data, and a Delphi survey, a framework for transferring knowledge to the organisation is proposed. The framework enables the organisation to motivate and guide knowledge transfer within a methodology that indicates where, when, and how knowledge transfer and use should take place.<hr/>Meganismes om lesse wat op projekte geleer is in 'n organisasie te gebruik, is ondersoek. 'n Delphi studie het die verantwoordelikheid van die organisasie t.o.v. die inkorporering van kennis in 'n projekbestuur-metodologie uitgelig. Kennis vanuit 'n projek behoort via 'n sentrale kennisbestuur-funksie oorgedra te word. Hierdie funksie moet gekodifiseerde kennis evalueer in die konteks waarin dit ontwikkel is, bepaal hoe die kennis gebruik behoort te word, en die databasis asook die kennis vloeiproses instand hou. Op grond van die literatuur, gestruktureerde onderhoude, geargiveerde data en 'n Delphi opname, word 'n raamwerk vir die oordrag van kennis na die organisasie voorgestel. Die raamwerk stel die organisasie in staat om die oordrag van kennis te motiveer en te lei in 'n metodologie wat aandui waar, wanneer en hoe kennisoordrag en benutting behoort plaas te vind. <![CDATA[<b>A normative model for assessing competitive strategy</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400004&lng=en&nrm=iso&tlng=en The hyper-competitive nature of e-business has raised the need for a generic way to appraise the merit of a developed business strategy. Although progress has been made in the domain of strategy evaluation, the established literature differs over the 'tests' that a strategy must pass to be considered well-constructed. This paper therefore investigates the existing strategy-evaluation literature to propose a more integrated and comprehensive normative strategic assessment that can be used to evaluate and refine a business's competitive strategy, adding to its robustness and survivability.<hr/>Die hiper-mededingende aard van e-besigheid het bygedra tot 'n groter behoefte vir 'n generiese manier om die meriete van 'n ontwikkelde besigheidstrategie te evalueer. Alhoewel daar alreeds vordering gemaak is in die strategie evaluering domein, wissel die bestaande literatuur beduidend in verband met die verskeie 'toetse' wat 'n strategie moet slaag om as 'goed' beskou te word. Hierdie artikel het daarom die bestaande strategie evaluering literatuur ondersoek en stel 'n meer geïntegreerde en omvattende normatiewe strategiese evaluering voor. Dié evaluering kan gebruik word om die kompeterende strategieë van besighede te evalueer en te verfyn, en dra daardeur by tot die besigheid se robuustheid en oorlewing. <![CDATA[<b>A technologically-driven asset management approach to managing physical assets - a literature review and research agenda for 'smart' asset management</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400005&lng=en&nrm=iso&tlng=en The concept of 'smart' is increasingly used in the commercial environment, and relates to a perception of technological intelligence. The concept of 'Internet of Things' (loT) has also become a reality that makes a different approach to managing physical assets necessary. With this technological intelligence come vast quantities of asset data and the analysis thereof, which has proven to add value to asset management. To capitalise on and expand this value creation, smart asset management (SAM) came into being by incorporating proven methodologies and applying these in real-time management structures. This article offers a review of the existing literature, and aims to create industry awareness about the business potential of incorporating SAM into automated asset environments for strategic management decision-making.<hr/>Die uitdrukking 'slim', wat met die persepsie van tegnologiese intelligensie verband hou, is 'n konsep wat toenemend binne die kommersiële omgewing gebruik word. Die 'loT' ("Internet of Things") konsep dra verder by tot die behoefte aan verskillende benaderings tot batebestuur. Meer waarde word aan batebestuur geheg as gevolg van hierdie tegnologiese intelligensie wat binne batebestuur analise toegepas word. Vanuit hierdie agtergrond is 'slim batebestuur' ontwikkel. Dit is 'n nuwe benadering wat bestaande metodes inkorporeer en terselfdertyd binne eietydse bestuurstrukture toegepas word. Hierdie artikel gee 'n oorsig van die slim batebestuur literatuur, en poog om uit te brei op die voordele van slim batebestuur binne geoutomatiseerde bate-omgewings met die doel om strategiese bestuursbesluite te neem. <![CDATA[<b>Modelling the impact of mining on socio-economic infrastructure development - a system dynamics approach</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400006&lng=en&nrm=iso&tlng=en The contribution of mining activities to social infrastructure and human development is a complex socio-economic development issue in South Africa. Complexity theory has introduced a new approach to solving problems in social systems, recognising them as complex systems. The socio-economic development system in South Africa falls into this category of complex systems. Analysing such a system requires that a number of feedback loops and details about the issues be analysed simultaneously. This level of complexity is above a human's ability to comprehend without the aid of tools such as systems thinking and system dynamics. The causality between investment in infrastructure capacity and socio-economic development is dynamic. The relationship is influenced by exogenous feedback that, if not managed, is likely to reverse itself. This paper presents the results of a system dynamics modelling of the relationship, based on the principle of relative attractiveness developed in previous system dynamics research. A Monte Carlo analysis is used to determine the sensitivity of the system to changes in feedback. The paper concludes that the limits to growth in a socio-economic environment are determined by more factors than the availability of capital, and also include land capacity constraints and skills shortage.<hr/>Die bydrae van mynbou-aktiwiteite tot sosiale infrastruktuur en menslike ontwikkeling is 'n komplekse sosio-ekonomiese ontwikkeling kwessie in Suid-Afrika. Die kompleksiteitsteorie het 'n nuwe benadering tot die oplossing van probleme in sosiale stelsels gebring deur hulle as komplekse stelsels te benader en die sosio-ekonomiese ontwikkeling in Suid-Afrika val binne hierdie kategorie van komplekse stelsels. Die ontleding van so 'n stelsel vereis dat 'n aantal terugvoerlusse en besonderhede rondom die kwessies gelyktydig ontleed word. Hierdie vlak van kompleksiteit is bo menslike vermoë om te verstaan sonder die hulp van gereedskap soos stelsel denke en -dinamika. Die verwantskap tussen belegging in kapasiteit infrastruktuur en sosio-ekonomiese ontwikkeling is dinamies. Die verwantskap word beïnvloed deur eksterne terugvoer, en indien dit nie bestuur word nie is die verwantskap geneig om ook in die omgekeerde rigting neerslag te vind. Die artikel bied die resultate van 'n dinamiese stelsels-modellering van die verwantskap wat gebaseer is op die beginsel van relatiewe aantreklikheid en wat ontwikkel is vanuit vorige stelseldinamika navorsing. 'n Monte Carlo analise word gebruik om die sensitiwiteit van die stelsel ten opsigte van verandering in terugvoer te bepaal. Een van die gevolgtrekkings in die navorsing is dat die grense van groei in 'n sosio-ekonomiese omgewing bepaal word deur meer faktore as die beskikbaarheid van kapitaal, wat die land kapasiteitsbeperkings en vaardigheidstekorte ook insluit. <![CDATA[<b>A framework for establishing a human asset register for the improved management of people in physical asset management</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400007&lng=en&nrm=iso&tlng=en People are fundamental to the success of managing physical assets. Line managers are increasingly becoming responsible for people-management activities that were traditionally placed within the human resources function, while often lacking effective people-management skills. A framework was developed to establish a human asset register to support asset managers in improving the management of people. The proposed framework provides a generic step-based approach to establishing a structured reflection of human dimensional information to facilitate the application of people management through asset managers. Structured expert interviews validated the proposed framework as providing a pragmatic method to solve the identified problem.<hr/>Mense is krities tot die suksesvolle bestuur van fisiese bates. Lynbestuurders word toenemend verantwoordelik vir menslike bestuursaktiwiteite, wat tradisioneel binne die menslike hulpbronbestuur afdeling geplaas is, maar daar is gereeld 'n tekort aan effektiewe menslike bestuursvaardighede. 'n Raamwerk is ontwikkel om 'n menslike bateregister saam te stel om sodoende batebestuurders te ondersteun om die bestuur van mense te verbeter. Die voorgestelde raamwerk verskaf 'n generiese stapsgewyse benadering om 'n gestruktureerde weerspieëling van menslike dimensionele informasie te bewerkstellig om sodoende die toepassing van menslike bestuur deur batebestuurders te fasiliteer. Gestruktureerde kenneronderhoude het die voorgestelde raamwerk gevalideer as 'n pragmatiese metode om die geïdentifiseerde probleem aan te spreek. <![CDATA[<b>A multi-period group technology method for dynamic cellular manufacturing systems</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400008&lng=en&nrm=iso&tlng=en A dynamic cellular manufacturing system is a system where cell configurations change in order to respond to changing production requirements. This paper proposes methods for multi-period cell and part family formation. The method of fuzzy C-means clustering is used for part family formation while balancing the part load between cells in each period; a genetic algorithm is presented to solve the model. An integer programming model is presented for multi-period cell formation with the objective of determining an optimal trade-off between reconfiguration cost and the cost of deficit capacity.<hr/>'n Dinamies sellulêre vervaardigingstelsel is 'n stelsel waarbinne selkonfigurasies verander in reaksie op veranderende produksie vereistes. 'n Metode van multi-periode sel en onderdeel familie formasie word voorgestel. Die wasige C-gemiddelde groeperings-metode word gebruik vir onderdeel familie vorming terwyl die onderdeel vereiste tussen die selle in elke periode gebalanseer word. n Genetiese algoritme word gebruik om die model op te los. n Heelgetal programmeringsmodel word voorgehou vir die multiperiode selformasie om die optimale kompromie tussen herkonfigurasie koste en die koste van tekorte in kapasiteit te bereik. <![CDATA[<b>Industrial engineering curriculum in Industry 4.0 in a South African context</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400009&lng=en&nrm=iso&tlng=en With its potential to change significantly the knowledge and skill-set requirements for industrial engineers (IEs), Industry 4.0 creates a need to reassess the place of IEs to avoid a greater shock than that caused by the information technology identity crisis of the 1990s. This article examines the likely impacts of Industry 4.0 on industrial engineering (IE) and proposes enhancements to IE curricula in South Africa. Research methods include a literature review, a study of IE curricula, and a questionnaire survey of IE programmes. Results indicate that several IE functions might become somewhat transformed, less visible, or downright diminished in Industry 4.0. Emphasis has shifted from traditional IE methods to data-driven functions and cyber-physical systems. The developing mismatch needs correcting by emphasising skills such as 'big data' analytics and novel human-machine interfaces in IE curricula. Only one university in South Africa has made progress towards the adoption of an Industry 4.0 infrastructure. The authors propose a set of curriculum enrichment items as the basis for reform.<hr/>Industrie 4.0 het die potensiaal om op 'n beduidende wyse die kennis en vaardigheid vereistes vir bedryfsingenieurs (BI) te verander. Dit skep ook 'n behoefte om die posisie van bedryfs-ingenieurs te herevalueer, om sodoende die informasie tegnologie identiteitskrisis van die 1990's te vermy. Hierdie artikel ondersoek die waarskynlike impak van Industrie 4.0 op BI met 'n voorgestelde verbeterde kurrikulum in Suid-Afrika. Navorsingsmetodes sluit in literatuuroorsig, BI kurrikulum studie, en 'n vraelys opname van BI programme. Die resultate dui daarop dat Industrie 4.0 sommige BI funksies ietwat sal transformeer, minder sigbaar maak, of selfs totaal verminder. Klem verskuif van die tradisionele BI metodes na meer data-gedrewe funksies en kuber-fisiese stelsels. Die ontwikkelingswanaanpassing vererger regstelling deur die beklemtoning van kurrikulum vaardighede soos byvoorbeeld groot datastel analise en nuwe mens-masjien koppelvlakke. Slegs een universiteit toon vordering in die aanvaarding van en implementering van Industrie 4.0 infrastruktuur. Die skrywers stel 'n stel kurrikulum verryking items as basis vir die hervorming voor. <![CDATA[<b>The effect of cutting parameters on surface integrity in milling Ti6Al4V </b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400010&lng=en&nrm=iso&tlng=en The objective of machining performance is to reduce operational costs and to increase the production rate while maintaining or improving the required surface integrity of the machined component. Together with industrial partners, several benchmark titanium components were selected and machined to achieve this. Titanium alloys are used extensively in several industries due to its unique strength-to-weight ratio and corrosion resistance. Its properties, however, also make it susceptible to surface integrity damage during machining operations. The research objectives of this study were to understand the effect of cutting parameters on surface integrity to ensure that machined components are within the required surface quality tolerances. The effect of cutting speed and feed rate on surface roughness, micro-hardness, and the microstructure of the work piece were studied for milling Ti6Al4V. The surface roughness increased with a greater feed rate and a decrease in cutting speed. The maximum micro-hardness was 23 per cent harder than the bulk material. Plastic deformation and grain rotation below the machined surface were found with the rotation of the grain lines in the direction of feed. There was no evidence of subsurface defects for any of the cutting conditions tested.<hr/>Die masjineringsvermoë doelwit bly steeds om operasionele kostes te verminder en om die produksietempo te verhoog, terwyl die vereiste oppervlakafwerking van die komponent gehandhaaf of verbeter word. Ten einde hierdie doelstelling te bereik is verskeie komponente in samewerking met industrievennote, as maatstaaf komponente gekies en gemasjineer. Titaan allooie word op groot skaal in verskeie industrieë gebruik vanweë sy unieke sterkte-tot-digtheid verhouding en korrosiebestandheid. Hierdie eienskappe maak die allooi egter ook vatbaar vir oppervlakafwerking skade tydens die masjineringsproses. Die navorsingsdoelstelling van hierdie studie was om die effek van die snyparameters op die oppervlakafwerking te verstaan, om sodoende te verseker dat die komponente binne die vereiste oppervlak toleransies vervaardig word. Die effek van snyspoed en voertempo tydens freeswerk op die oppervlak grofheid, mikrohardheid en mikrostruktuur van die Ti6Al4V werkstuk is bestudeer. Die oppervlakgrofheid het verhoog met 'n toename in voertempo en vermindering in snyspoed. Die maksimum mikrohardheid was 23 persent harder as die basismateriaal. Plastiese vervorming en korrel rotasie onder die gemasjineerde werkstuk oppervlak is gevind met die korrelgrein in die rigting van die voer. Daar was geen aanduiding van suboppervlak defekte onder enige van die toets kondisies nie. <![CDATA[<b>Critical review of the levelised cost of energy metric</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400011&lng=en&nrm=iso&tlng=en The purpose of this paper is to critically review the 'levelised cost of energy' metric used in electricity project development. This metric is widely used, because it is a simple metric to calculate the cost per unit of electricity for a given technology connected to the electricity network. However, it neglects certain key terms such as inflation, integration costs, and system costs. The implications of incorporating these additional costs would provide a more comprehensive metric for evaluating electricity generation projects, and for the system as a whole. It is therefore recommended to refine the metric for the South African context.<hr/>Die doel van hierdie artikel is om krities te kyk na die 'levelised cost of energy' meeteenheid wat gebruik word in die ontwikkeling van elektrisiteit projekte. Die meeteenheid word wyd gebruik, want dit is 'n eenvoudige manier om die koste per eenheid elektrisiteit te bereken vir 'n gegewe tegnologie wat verbind is aan die elektrisiteitsnetwerk. Maar dit laat sekere sleutelterme, soos inflasie, integrasie koste, en stelselkostes, na. Die implikasies van die uitvoering van hierdie bykomende kostes sal 'n meer omvattende meeteenheid daarstel vir die evaluering van elektrisiteit-opwekkingsprojekte, en die totale elektrisiteitstelsel. Dit word dan aanbeveel om die meeteenheid vir die Suid-Afrikaanse konteks te verfyn. <![CDATA[<b>Residual stress in Ti6Al4V objects produced by direct metal laser sintering</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400012&lng=en&nrm=iso&tlng=en Direct Metal Laser Sintering produces 3D objects using a layer-by-layer method in which powder is deposited in thin layers. Laser beam scans over the powder fusing powder particles as well as the previous layer. High-concentration of laser energy input leads to high thermal gradients which induce residual stress within the as-built parts. Ti6Al4V (ELI) samples have been manufactured by EOSINT M280 system at prescribed by EOS process-parameters. Residual stresses were measured by XRD method. Microstructure, values and directions of principal stresses inTi6Al4V DMLS samples were analysed.<hr/>Direkte laser metaal sintering vervaardig driedimensionele voorwerpe deur gebruik van 'n laag-op-laag metode waar poeier in dun lae gedeponeer word. Die laser straal skandeer die poeier en smelt die deeltjies en die vorige laag aan mekaar. Die hoë konsentrasie van laser energie inset lei na hoë termiese gradiënte wat veroorsaak dat daar res-spanning in die onderdele is. Tot op hede is monsters vervaardig deur die EOSINT M280 sisteem teen voorgeskrewe EOS proses paremeters vir Ti6Al4V (ELI) poeier. Argon is gebruik as die beskermingsatmosfeer. Res-spanning is gemeet met die XRD (bestraling diffraksie) metode. Mikrostruktuur, waardes en rigting van hoof spanning in Ti6Al4V monsters is ontleed. <![CDATA[<b>A decision-making framework for effective maintenance management using life cycle costing (LCC) in a rolling stock environment</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400013&lng=en&nrm=iso&tlng=en In this paper, a life cycle costing (LCC) framework for effective maintenance management is investigated and developed for use in a railway rolling stock environment. The framework consists of combining typical mission-critical components together with their failure and maintenance history. All costs related to the operation and maintenance of these components throughout their life cycle are also determined. The next step involves considering different scenarios under which the components can be used in relation to operations, maintenance, and replacements. The decision about which scenario to take is based on the one with the most favourable net present value after life cycle costing is performed over a specified period of time. A typical railway rolling-stock maintenance organisation in South Africa was used to highlight the practical implications of such a framework and how the company could make informed and appropriate decisions. The conclusion of this study is that such a framework is useful, and that it can be used as a basis for estimating LCC across a spectrum of critical assets found in the rolling stock environment.<hr/>In hierdie artikel is 'n lewenssikluskoste raamwerk ondersoek en ontwikkel om instandhoudingsbestuur in 'n spoorweg rollende materiaal omgewing te verbeter. Die raamwerk bestaan uit 'n kombinasie van tipiese missie-kritiese komponente saam met hulle falings- en instandhoudingsgeskiedenis. Alle koste verbonde aan die bedryf en instandhouding van hierdie komponente gedurende hulle lewenssiklus is ook bepaal. Deur verskillende bedryfscenario's se lewenssikluskoste te vergelyk in terme van netto huidige waardes, kan 'n besluit oor die beste scenario geneem word. 'n Suid-Afrikaanse gevallestudie is gebruik om die waarde van hierdie raamwerk te illustreer. Resultate toon dat die raamwerk wel bruikbaar is oor 'n wye spektrum van scenario's. <![CDATA[<b>An approach to evaluating alternatives for wind power plant locations</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400014&lng=en&nrm=iso&tlng=en Multi-criteria decision approaches are preferred for achieving multidimensional sustainable renewable energy goals. A more critical issue faced by the wind power industry is the selection of a location to tap prospective energy, which needs to be evaluated on multiple measures. In this paper, the aim is to assess and rank alternative wind power plant locations in Saudi Arabia. The approach presented here takes multiple criteria into consideration, such as wind speed, wind availability, site advantages, terrain details, risk and uncertainty, technology used, third party support, projected demand, types of customers, and government policies. A comparative analysis of feasible alternatives that satisfy all multi-criteria objectives is carried out. The results obtained are subjected to sensitivity analysis. Concepts such as 'threshold values' and 'attribute weights' make the approach more sensitive.<hr/>Multikriteria besluitnemingsbenaderings word verkies om multi-dimensionele, volhoubare en hernubare energie doelstellings te bereik. 'n Belangrike kwessie vir die windkragindustrie is die identifisering van 'n geskikte ligging wat onderhewig is aan verskeie kriteria. Hierdie artikel assesseer en rangskik verskeie potensiële windkragopwekking liggings in Saoedi-Arabië. Die voorgestelde benadering neem meervoudige kriteria, onder andere wind spoed en wind beskikbaarheid, ligging voordele, terrein detail, risiko en onsekerheid, die tegnologie wat gebruik word, derdeparty ondersteuning, geprojekteerde vraag, die tipe kliënte en regeringsbeleide, in ag. 'n Vergelykende analise van uitvoerbare alternatiewe wat aan al die kriteria doelstellings voldoen is uitgevoer. Die daaropvolgende resultate is dan aan 'n sensitiwiteitsanalise onderwerp. Konsepte soos drempelwaardes en eienskapgewigte maak die benadering meer sensitief. <![CDATA[<b>Investigating a green economy transition of the electricity sector in the Western Cape Province of South Africa: a system dynamics approach</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400015&lng=en&nrm=iso&tlng=en The Western Cape Government in South Africa has identified the concept of a green economy as a way to transform the Province's economy to one that is more sustainable from an economic, social, and environmental perspective. System dynamics modelling was used to develop a better understanding of the implications of different green economy policies and investments in the electricity sector of the Western Cape Province. The results suggest that continuing on the current policy path would increase the gap between demand and supply, increase the carbon footprint of the electricity sector, and not provide growth in employment in the sector. Strategic green economy investments are therefore expected to impact positively on a number of indicators across a number of sectors.<hr/>Die Wes-Kaapse Regering van Suid-Afrika het die konsep van die groen ekonomie geïdentifiseer as 'n werktuig om die provinsie se ekonomie te omskep in een wat meer volhoubaar is van 'n ekonomiese, sosiale, en omgewings perspektief af. Stelseldinamika modellering was gebruik om 'n beter begrip te ontwikkel van die moontlike voordele en impakte wat verskillende groen ekonomie beleide en beleggings in die elektrisiteits-sektor van die Wes-Kaap kan bewerkstellig. Die resultate van die modellering stel voor dat die voortsetting van die huidige beginsels en beleid sal lei tot 'n groter gaping tussen die aanvraag en die verskaffing van elektriese krag, 'n groter koolstofvoetspoor van die elektrisiteits-sektor, en geen groei in die werkverskaffing van die sektor nie. Daar word verwag dat strategiese groen ekonomie beleggings 'n positiewe impak sal bewerkstellig in menigte aanwysers. <![CDATA[<b>Regional economic assessment of the planned De Beers Pass Road project in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400016&lng=en&nrm=iso&tlng=en This article analyses the magnitude of the possible regional economic impacts that might stem from the proposed De Beers Pass Route (DBPR) project in South Africa. The regional income multiplier and income accelerator analysis are used to estimate the gross and net once-off increase in regional income during construction, and the recurring increases in regional income during road use. The difference between a cost-benefit analysis and a regional economic income analysis is indicated. To end, guiding pointers are supplied on the appropriate use of independent variables when applying the regional income multiplier-accelerator model.<hr/>In hierdie artikel word die moontlike streekontwikkelingsimpakte wat uit die voorgestelde De Beerspas-padprojek in Suid-Afrika kan spruit, ontleed. 'n Werkswyse word getoon waardeur die bruto en netto eenmalige verhoging in streeksinkomste tydens konstruksie deur vermenigvuldiger-ontleding en die herhalende streeks-inkomste tydens padgebruik deur versneller-ontleding beraam kan word. Onderskeid word getref tussen 'n kostevoordeelontleding en 'n streeksekonomiese-inkomste-ontleding. Laastens word aanwysings verskaf oor die gepaste toepassing van onafhanklike veranderlikes by die berekening van die streeksinkomste-vermenigvuldiger en -versnellermodel. <![CDATA[<b>The analysis of human error as causes in the maintenance of machines: a case study in mining companies</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400017&lng=en&nrm=iso&tlng=en This paper describes the two-step method used to analyse the factors and aspects influencing human error during the maintenance of mining machines. The first step is the cause-effect analysis, supported by brainstorming, where five factors and 21 aspects are identified. During the second step, the group fuzzy analytic hierarchy process is used to rank the identified factors and aspects. A case study is done on mining companies in Serbia. The key aspects are ranked according to an analysis that included experts who assess risks in mining companies (a maintenance engineer, a technologist, an ergonomist, a psychologist, and an organisational scientist). Failure to follow technical maintenance instructions, poor organisation of the training process, inadequate diagnostic equipment, and a lack of understanding of the work process are identified as the most important causes of human error.<hr/>'n Twee-stap metode om die faktore en aspekte wat menslike foute gedurende die instandhouding van mynmasjinerie beïnvloed, word beskryf. Die eerste stap is die oorsaak-gevolg analise, wat met 'n dinkskrum ondersteun word, waartydens vyf faktore en een-en-twintig aspekte identifiseer word. Tydens die tweede stap word die groep-wasigheid-hiërargie analise proses gebruik om die geïdentifiseerde faktore en aspekte te rangskik. 'n Gevallestudie is op mynondernemings in Serwië geloods. Die sleutelaspekte is rangskik volgens 'n analise wat mynonderneming risiko kenners ('n instandhoudingsingenieur, 'n tegnoloog, 'n ergonoom, 'n sielkundige en 'n organisatoriese wetenskaplike) ingesluit het. Nalating om tegniese instandhoudingsinstruksies te volg, swak organisasie van die opleidingsproses, onvoldoende diagnostiese toerusting en n tekort aan die verstaan van die werksprosesse is geïdentifiseer as die belangrikste oorsake van menslike foute. <![CDATA[<b>The effect of scope definition on infrastructure projects: a case in Malawi's public and private implementing agencies</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400018&lng=en&nrm=iso&tlng=en This research was carried out to determine the effect of scope definition on public building projects that are implemented by project implementing agencies (PIAs) in Malawi. The research sought to investigate the relationship between the level of scope definition and the corresponding performance of infrastructure projects. The study demonstrated the correlation between the level of project scope definition and the success of infrastructure projects. A project scope definition tool called the 'project definition rating index' (PDRI) was used in this research to measure the level of project scope definition. The research concluded that there is a significant direct correlation between scope definition and the corresponding performance of the sampled infrastructure projects in Malawi's PIAs. Projects that were well-defined tended to exhibit good project performance indicators, while those that were poorly-defined tended to exhibit poor project performance indicators.<hr/>Hierdie navorsing is uitgevoer om die effek wat omvang definisie het op openbare bouprojekte wat deur projek uitvoering agentskappe (PIA) in Malawi geïmplementeer word, te bepaal. Die navorsing poog om die verhouding tussen die vlak van omvang definisie en die ooreenstemmende prestasie van infrastruktuur-projekte te ondersoek. Die studie toon verder die korrelasie tussen die vlak van die projek omvang definisie en die sukses van infrastruktuurprojekte. 'n Projek omvang definisie instrument genoem 'Project Definition Rating Index' (PDRI) is in hierdie navorsing gebruik om die vlak van die projek omvang definisie te meet. Die navorsing se gevolgtrekking is dat daar 'n beduidende direkte korrelasie tussen omvang definisie en die ooreenstemmende prestasie van die tersaaklike groep infrastruktuurprojekte in die PIA van Malawi is. Projekte wat goed gedefinieer is was geneig om goeie projek prestasie-aanwysers te toon, terwyl diegene wat swak gedefinieer is geneig was om swak projek prestasie-aanwysers te toon. <![CDATA[<b>A multi-objective coal inventory management model using Monte Carlo computer simulation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400019&lng=en&nrm=iso&tlng=en The ability of a coal-fired power station to meet its generation targets is influenced by periods of coal shortage. In this article, we propose a multi-objective inventory model to assist with the management of coal stockpiles. The model is applicable to power utilities with a network of two or more coal-fired power stations. The aim is to determine the near-optimal amount of coal inventory to stockpile at each station in the network. A Monte Carlo coal stockpile simulator is used to incorporate stochastic uncertainty into the stockpile levels, while a metaheuristic uses the simulator as an estimator of two objective functions. The metaheuristic finds good values for the coal stockpile level at each power station in the network. The algorithm for multi-objective optimisation using the cross-entropy method is proposed as a suitable metaheuristic. A hypothetical case study is used to validate the inventory model and to showcase the optimisation results.<hr/>Die vermoë van 'n steenkool-aangedrewe kragsentrale om sy opwekkingteikens te bereik word beïnvloed deur periodes van 'n steenkooltekort. In hierdie artikel stel ons 'n meerdoelige voorraadmodel voor om te help met die bestuur van steenkoolvoorraad. Die model is van toepassing op elektrisiteitsverskaffers met 'n netwerk van twee of meer steenkoolaangedrewe kragsentrales. Die doel is om die naby-optimale steenkoolvoorraadvlak te bepaal wat by elke kragsentrale in die netwerk gestoor moet word. 'n Monte Carlo steenkool voorraad-simulator word gebruik om stogastiese onsekerheid in die steenkoolverbruik te inkorporeer, terwyl 'n metaheuristiek die simulator gebruik as 'n beramer vir twee doelfunksies. Die metaheuristiek vind goeie waardes vir steenkoolvlakke by elke kragsentrale in die leweringsnetwerk. Die algoritme vir meerdoelige optimering met die kruis-entropie metode word voorgestel as 'n geskikte metaheuristiek. 'n Hipotetiese gevallestudie word gebruik om die voorraadmodel te valideer en optimeringsresultate te toon. <![CDATA[<b>An efficiency reporting system for organisational sustainability based on work study techniques</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-78902016000400020&lng=en&nrm=iso&tlng=en This article aims to demonstrate that work study techniques must be used to determine standard times for operations and to develop efficiency reporting systems to sustain organisations. Many organisations do not measure their efficiencies and do not have reporting systems. This article presents an efficiency reporting system designed and based on work study techniques that can be used to measure performance. The empirical results of the research instrument supported the need for the system. The existence of a dedicated efficiency reporting system ensures that employee performance and outputs in line with set targets are measured and sustained.<hr/>Hierdie artikel demonstreer dat werkstudietegnieke gebruik moet word om die standaard tye vir operasies te bepaal asook vir die ontwikkeling van doeltreffende rapporteringstelsels sodat organisasies volhoubaar kan wees. Baie organisasies meet nie hulle doeltreffendheid nie en het nie stelsels wat terugvoer akkommodeer nie. Hierdie artikel bied 'n doeltreffende rapporteringstelsel ontwerp aan wat gebaseer is op werkstudietegnieke wat gebruik kan word om prestasie te meet. Die empiriese resultate van die navorsingsinstrument bewys die noodsaaklikheid vir hierdie stelsel. Die bestaan van 'n doeltrefferede rapporteringstelsel verseker dat werknemer prestasie en uitsette gemeet en volgehou kan word volgens 'n stel voorafbepaalde teikens.