Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Neck pain is a common phenomenon that occurs in a large percentage of the population every day. While many occurrences are not deemed critical such as those from muscle strain which can be treated with rest and pain medication, others due to sports injuries, whiplash from car accidents, bad posture or degeneration of the intervertebral disc can be quite severe. In extreme cases failure of the vertebra(e) or the intervertebral disc requires surgery and possibly the use of cervical implants. Where intervertebral discs fail due to herniation or Degenerative Disc Disease (DDD), Anterior Cervical Discectomy and Fusion (ACDF) is a common surgical method used to remove the a ected disc and replace it with a cervical cage implant. These implants are designed to restore the height between the vertebrae, allowing bone from both vertebrae to grow through them and mineralise. Additive Manufacturing (AM) technologies can produce parts with complex geometries not possible using conventional manufacturing methods. This design freedom, coupled with CT scans of a patient, allow for tailoring an implant to the speci c anatomy of the a ected vertebrae using CAD software. Such an approach must be regulated and shown to be technically and commercially feasible before it can be implemented in industry. This study sought to develop a framework for manufacturing customized cervical cage implants using additive manufacturing. The e cacy of customization to reduce the risk of subsidence was investigated by means of non-destructive and destructive mechanical testing on six cadaver specimens, using readily available PEEK cage implants as a benchmark. The results showed that the customized implant was comparable to the PEEK, with no statistically signi cant di erence between the two. In extreme cases, where PEEK implants cannot be used, customized implants could be a suitable alternative to reduce the risk of subsidence. A manufacturing cost analysis was conducted to determine economic feasibility. The estimated cost and selling price of the customized implants under various utilization scenarios and mark-ups was compared to readily available PEEK implants. The estimated selling prices of the customized implants compared favourably to the PEEK verifying the economic viability of using AM. / AFRIKAANSE OPSOMMING: Nek pyn is 'n algemene verskynsel wat daagliks na tevore kom in die bevolking. Baie gevalle word nie as krities geklasi seer nie soos byvoorbeeld spier pyn wat behandel kan word deur genoegsame rus en pyn medikasie. Pyn wat deur sportbeserings, sweepslag beserings 'whiplash' tydens motor ongelukke, verkeerde postuur, of deur slytasie van 'n intervertebrale skyf veroorsaak is, word dikwels as ernstig geklasi seer. In ekstreme gevalle waar die werwel(s) of die inervertebrale skyf(we) faal, sal chirurgie en servikale inplantate moontlik nodig wees. Waneer intervertebrale skywe faal weens herniatie of Degeneratiewe Skyf Siekte (DDD) kan 'n algemene chirurgiese metode, Anterieure Servikale Discectomie en Fusie (ACDF), gebruik word om die gea ekteerde skyf te verwyder en dit te vervang met 'n servikale samesmelting implantaat. Hierdie implantate herstel die hoogte tussen rugwerwels en is ontwerp sodat die been deur dit kan groei en mineraliseer. Komplekse geometrieë kan vervaardig word deur toevoegingsvervaardiging (AM) tegnologieë. Die ontwerp vryheid, gepaard met CT-skanderings en CAD-sagteware stel mens in staat om die geometrie van die implantaat aan te pas tot die spese eke anatomie van die gea ekteerde vertebra. So 'n benadering moet gereguleer word en eers tegnies en kommersieel uitvoerbaar bewys word voordat dit in die bedryf geïmplementeer kan word. Hierdie studie poog verder om 'n raamwerk vir die vervaardiging van persoonlike servikale implantate deur middel van toevoegingsvervaardiging te ontwikkel. Die doeltre endheid van persoonlike implantate om te verhoed dat die chirurg die eind-plaat beskadig, en sodoende die risiko van insakking te verminder, is ondersoek deur middel van meganiese toetse op ses kadawer monsters. Hierdie toetse is gedoen met behulp van geredelik beskikbaar PEEK servikale implantate as 'n maatstaf. Die resultate het getoon dat die persoonlike- en PEEK implantate vergelykbaar is. In moontlike gevalle waar PEEK implantate nie geskik sou wees nie, kan persoonlike implantate 'n alternatiewe opsie wees om die risiko van insakking te verminder.

Thesis (PhD (Industrial Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The crucial role of innovation in creating sustainable competitive advantage is widely recognised in industry today. Likewise, the importance of having the required information accessible to the right employees at the right time is well-appreciated. More specifically, the dependency of effective, efficient innovation processes on the availability of information has been pointed out in literature. A great challenge is countering the effects of the information overload phenomenon in organisations in order for employees to find the information appropriate to their needs without having to wade through excessively large quantities of information to do so. The initial stages of the innovation process, which are characterised by free association, semi-formal activities, conceptualisation, and experimentation, have already been identified as a key focus area for improving the effectiveness of the entire innovation process. The dependency on information during these early stages of the innovation process is especially high. Any organisation requires a strategy for innovation, a number of well-defined, implemented processes and measures to be able to innovate in an effective and efficient manner and to drive its innovation endeavours. In addition, the organisation requires certain enablers to support its innovation efforts which include certain core competencies, technologies and knowledge. Most importantly for this research, enablers are required to more effectively manage and utilise innovation-related information. Information residing inside and outside the boundaries of the organisation is required to feed the innovation process. The specific sources of such information are numerous. Such information may further be structured or unstructured in nature. However, an ever-increasing ratio of available innovation-related information is of the unstructured type. Examples include the textual content of reports, books, e-mail messages and web pages. This research explores the innovation landscape and typical sources of innovation-related information. In addition, it explores the landscape of text analytical approaches and techniques in search of ways to more effectively and efficiently deal with unstructured, textual information. A framework that can be used to provide a unified, dynamic view of an organisation‟s innovation-related information, both structured and unstructured, is presented. Once implemented, this framework will constitute an innovation-focused knowledge base that will organise and make accessible such innovation-related information to the stakeholders of the innovation process. Two novel, complementary text analytical techniques, Latent Dirichlet Allocation and the Concept-Topic Model, were identified for application with the framework. The potential value of these techniques as part of the information systems that would embody the framework is illustrated. The resulting knowledge base would cause a quantum leap in the accessibility of information and may significantly improve the way innovation is done and managed in the target organisation. / AFRIKAANSE OPSOMMING: Die belangrikheid van innovasie vir die daarstel van „n volhoubare mededingende voordeel word tans wyd erken in baie sektore van die bedryf. Ook die belangrikheid van die toeganklikmaking van relevante inligting aan werknemers op die geskikte tyd, word vandag terdeë besef. Die afhanklikheid van effektiewe, doeltreffende innovasieprosesse op die beskikbaarheid van inligting word deurlopend beklemtoon in die navorsingsliteratuur. „n Groot uitdaging tans is om die oorsake en impak van die inligtingsoorvloedverskynsel in ondernemings te bestry ten einde werknemers in staat te stel om inligting te vind wat voldoen aan hul behoeftes sonder om in die proses deur oormatige groot hoeveelhede inligting te sif. Die aanvanklike stappe van die innovasieproses, gekenmerk deur vrye assosiasie, semi-formele aktiwiteite, konseptualisering en eksperimentasie, is reeds geïdentifiseer as sleutelareas vir die verbetering van die effektiwiteit van die innovasieproses in sy geheel. Die afhanklikheid van hierdie deel van die innovasieproses op inligting is besonder hoog. Om op „n doeltreffende en optimale wyse te innoveer, benodig elke onderneming „n strategie vir innovasie sowel as „n aantal goed gedefinieerde, ontplooide prosesse en metingskriteria om die innovasieaktiwiteite van die onderneming te dryf. Bykomend benodig ondernemings sekere innovasie-ondersteuningsmeganismes wat bepaalde sleutelaanlegde, -tegnologiëe en kennis insluit. Kern tot hierdie navorsing, benodig organisasies ook ondersteuningsmeganismes om hul in staat te stel om meer doeltreffend innovasie-verwante inligting te bestuur en te gebruik. Inligting, gehuisves beide binne en buite die grense van die onderneming, word benodig om die innovasieproses te voer. Die bronne van sulke inligting is veeltallig en hierdie inligting mag gestruktureerd of ongestruktureerd van aard wees. „n Toenemende persentasie van innovasieverwante inligting is egter van die ongestruktureerde tipe, byvoorbeeld die inligting vervat in die tekstuele inhoud van verslae, boeke, e-posboodskappe en webbladsye. In hierdie navorsing word die innovasielandskap asook tipiese bronne van innovasie-verwante inligting verken. Verder word die landskap van teksanalitiese benaderings en -tegnieke ondersoek ten einde maniere te vind om meer doeltreffend en optimaal met ongestruktureerde, tekstuele inligting om te gaan. „n Raamwerk wat aangewend kan word om „n verenigde, dinamiese voorstelling van „n onderneming se innovasieverwante inligting, beide gestruktureerd en ongestruktureerd, te skep word voorgestel. Na afloop van implementasie sal hierdie raamwerk die innovasieverwante inligting van die onderneming organiseer en meer toeganklik maak vir die deelnemers van die innovasieproses. Daar word verslag gelewer oor die aanwending van twee nuwerwetse, komplementêre teksanalitiese tegnieke tot aanvulling van die raamwerk. Voorts word die potensiele waarde van hierdie tegnieke as deel van die inligtingstelsels wat die raamwerk realiseer, verder uitgewys en geillustreer.

Thesis (PhD (Industrial Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Injection moulding of polymer components is subject to ever increasing demands for improved part quality and production rate. It is widely recognised that the mould cooling strategy employed is crucial to achieving these goals. A brief overview of injection moulding units and different types of injection moulds is given. The modern Additive Manufacturing (AM) technology for processing metal powders such as Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) offers almost full freedom to the mould designer. Some of these modern manufacturing methods based on metal powders, which are able to produce complex cooling channels are analysed. A drastic change has entered the mould design domain - shifting the paradigm from design for manufacture to manufacture for design. In combination with suitable AM methods the concept of surface cooling moulds can now be efficiently implemented. This study presents a new approach of predicting the minimum cooling time required for the produced part. Different cooling layouts are analysed taking the heat transfer into consideration. The lumped heat capacity method is implemented in this research in order to determine the minimum cooling cycle time required. A new approach was developed to determine the most suitable cooling layout configuration, such as conventional cooling, conformal cooling or surface cooling, required for a moulded part based on its characteristics such as shape complexity, space available for the cooling layout, part quality requirements, production volume, and product life cycle. A mould cooling design process including simulation, reverse engineering and manufacturing of the mould insert was implemented in this study. In order to validate the generic model developed during the course of this research comparative experiments were carried out to determine the difference in performance of injection moulding using conventional or surface cooling methods. The experimental results showed a significant improvement in part quality produced with reduced cycle times using the surface cooling method. / AFRIKAANSE OPSOMMING: ‘Injection Moulding’ van polimeer komponente word al meer gedruk vir verbeterde kwaliteit en vinniger produksie tyd. Dit is orals bekend dat die gietvorm afkoeling strategie ‘n groot rol speel om hierdie twee doelwitte te bereik. Eers word ‘n kort oorslag gegee van ‘Injection Moulding’ eenhede en van verskillende ‘Injection Moulding’ vorms. Die moderne Aditatiewe Vervaardigingstegnologie vir die prosessering van metaal poeiers soos bv. Direkte Metaal Laser Sintering (DMLS) en Selektiewe Laser Smelting (SLM) bied basies volle vryheid ten opsigte van gietvorm ontwerp. Party van die moderne vervaadigings metodes, wat op metaal poeiers gebaseer is, wat komplekse koelings kanale kan produseer word geanaliseer. Die ontwerpers arena het ‘n groot verandering ondergaan deurdat die fokus van ontwerp vir vervaardiging verskuif het na vervaardiging vir ontwerp. In kombinasie met toepaslike aditatiewe vervaardigings metodes kan oppervlak verkoeling nou effektief geïmplementeer word. Hierdie studie bied a nuwe manier om die minimum verkoelings tyd benodig vir ‘n part te voorspel. Verskeie verkoelings uitlegte word geanaliseer waar hitte oordrag in ag geneem word. Die “lumped heat capacity” metode word gebruik om die minimum siklus tyd te bepaal. ‘n Nuwe benadering is ontwikkel om die mees geskikste verkoelings uitleg soos bv. konvensionele verkoeling, konvorme verkoeling of oppervlak verkoeling te bepaal vir ‘n spesifieke part gebaseer op die part se vorm kompleksiteit, spasie beskikbaar vir verkoelings kanale, kwaliteit vereistes en produk lewensiklus. Die volgende is in die studie geïmplementeer: ‘n vorm verkoelings ontwerp proses met simulasie, ‘reverse engineering’ en vervaardiging van die vorm insetsel. Om die generiese model te verifieer gedurende die studie is vergelykende eksperimente uitgevoer om die verskil in prestasie te bepaal tussen die gebruik van konvensionele en oppervlak verkoelings metodes. Die eksperimentele resultate het ‘n beduidende verbetering in part kwaliteit getoon met ‘n verkorte siklus tyd tydens die gebruik van die oppervlag verkoelings metode.

Thesis (PhD)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: A telemedicine service is a healthcare service (-medicine) that is delivered over a distance (tele-). The interest in the potential of telemedicine to increase the quality, accessibility, utilization, e ciency and e ectiveness of healthcare services is fuelled by the rapid development of information and communication technology (ICT) and connectivity. Despite this potential, the success rate of telemedicine services disappoints. Many mistakes in the implementation of telemedicine services are repeated over and over again and best practices are not captured and replicated. This study responds to the need for reference models for the assessment and optimization of telemedicine services in a consistent, systematic and systemic way. Maturity models are reference models that describe typical patterns in the development of organizational capabilities and depict a sequence of stages towards the desired state. Many reference models exist that are applicable to telemedicine services, but none of these provide guidance for the optimization of services, like a maturity model does. Many maturity models exist within a health systems context, but none of these can be applied "as is" to telemedicine services. In this study an iterative top-down design approach is followed to develop a Telemedicine Service Maturity Model (TMSMM). This model facilitates the assessment of a telemedicine service on micro, meso, and macrolevel along all the domains that comprise the telemedicine health system. Sets of capability statements are de ned, which follow each other in a cumulative manner, hence providing a maturation path towards the desired maturity state. These sets of capability statements provide yardsticks according to which quantitative values are allocated to an intangible concept, such as maturity. Once an individual service is assessed, further actions towards the optimization of the service can be derived from these yardsticks. The multidimensional design of the TMSMM, as well as the fact that capability statements facilitate the consistent quanti cation of maturity, makes it possible to analyze the aggregated results of cohort of services. To accomplish this, principles of business intelligence and data warehouse design are applied together with online analytic processing (OLAP) procedures. The TMSMM addresses the previously unful lled need for a reference model to assess and optimize telemedicine services in a consistent, systematic and systemic way. This study spans several academic and professional domains and thereby contributes to the scienti c world of telemedicine and ehealth. / AFRIKAANSE OPSOMMING: 'n Telegeneeskunde diens is 'n gesondheidsdiens (-geneeskunde) wat oor 'n afstand gelewer word (tele-). Met die snelle ontwikkeling van inligtings-en kommunikasietegnologie hou telegeneeskunde die potensiaal in om die kwaliteit, toeganklikheid, benutting, doelmatigheid en doeltre endheid van gesondheidsdienste te verhoog. Ten spyte van hierdie potensiaal, stel die aantal onsuksesvolle telegeneeskunde dienste teleur. Heelwat foute in die implementering van telegeneeskundedienste word oor en oor gemaak, terwyl die beste praktyke nie vasgevang en herhaal word nie. Hierdie studie is onderneem in reaksie op die behoefte aan 'n verwysingsmodel vir die assessering en optimering van telegeneeskunde dienste op 'n konsekwente, sistematiese en sistemiese manier. Volwassenheidsmodelle is verwysingsmodelle wat tipiese patrone in die ontwikkeling van organisatoriese vermoeëns beskryf. Dit stip 'n aantal fases neer wat uiteindelik behoort te lei na die ideale organisatoriese toestand. Daar bestaan verskeie verwysingsmodelle wat van toepassing is op telegeneeskunde dienste, maar geeneen daarvan gee leiding met die oog op die optimering van die diens, soos in die geval van 'n volwassenheidsmodel nie. In hierdie studie word 'n iteratiewe van-bo-na-onder ontwerpsbenadering gevolg om 'n telegeneeskunde volwassenheidsmodel (TMSMM) te ontwikkel. Hierdie model fasiliteer die assessering van 'n telegeneeskunde diens op 'n mikro-, mesoen makrovlak en met betrekking to al die fasette waaruit 'n telegeneeskunde stelsel bestaan. 'n Aantal vermoeëstellings is gede nieer. Hierdie stellings volg op mekaar en akkumuleer om sodoende 'n volwassenheidspad na die verlangde toestand aan te dui. Hierdie vermoeëstellings verskaf maatstawwe waarvolgens kwantitiewe waardes toegeken kan word aan 'n ontasbare konsep, soos volwassenheid. Sodra 'n individuele diens geassesseer is, kan verdere aksies met die oog op die optimering van die diens afgelei word. Die multidimensionele ontwerp van die TMSMM, tesame met die feit dat die vermoeëstellings volwassenheid op 'n konsekwente manier kwanti seer, maak dit moontlik dat die data van 'n kohort dienste saamgevoeg kan word met die oog op analise. Beginsels van besigheidsintelligensie, datastoorontwerp asook aanlyn analitiese prosessering (OLAP) word hiervoor ingespan. Die TMSMM spreek tot die voorheen onvervulde behoefte aan 'n verwysingsmodel waarmee telegeneeskunde dienste geassesseer in geoptimeer word in 'n konsekwente, sistematiese en sistemiese manier. Hierdie studie strek oor verskeie akademiese en professionele domeine en lewer sodoende 'n bydrae tot die multidissiplinêre wetenskapswêreld van telegeeskunde en e-gesondheid.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The domination number of a graph is the cardinality of a smallest subset of its vertex set with the property that each vertex of the graph is in the subset or adjacent to a vertex in the subset. This graph parameter has been studied extensively since its introduction during the early 1960s and finds application in the generic setting where the vertices of the graph denote physical entities that are typically geographically dispersed and have to be monitored efficiently, while the graph edges model links between these entities which enable guards, stationed at the vertices, to monitor adjacent entities. In the above application, the guards remain stationary at the entities. In 2005, this constraint was, however, relaxed by the introduction of a new domination-related parameter, called the secure domination number. In this relaxed, dynamic setting, each unoccupied entity is defended by a guard stationed at an adjacent entity who can travel along an edge to the unoccupied entity in order to resolve a security threat that may occur there, after which the resulting configuration of guards at the entities is again required to be a dominating set of the graph. The secure domination number of a graph is the smallest number of guards that can be placed on its vertices so as to satisfy these requirements. In this generalised setting, the notion of edge removal is important, because one might seek the cost, in terms of the additional number of guards required, of protecting the complex of entities modelled by the graph if a number of edges in the graph were to fail (i.e. a number of links were to be eliminated form the complex, thereby disqualifying guards from moving along such disabled links). A comprehensive survey of the literature on secure graph domination is conducted in this dissertation. Descriptions of related, generalised graph protection parameters are also given. The classes of graphs with secure domination number 1, 2 or 3 are characterised and a result on the number of defenders in any minimum secure dominating set of a graph without end-vertices is presented, after which it is shown that the decision problem associated with computing the secure domination number of an arbitrary graph is NP-complete. Two exponential-time algorithms and a binary programming problem formulation are presented for computing the secure domination number of an arbitrary graph, while a linear algorithm is put forward for computing the secure domination number of an arbitrary tree. The practical efficiencies of these algorithms are compared in the context of small graphs. The smallest and largest increase in the secure domination number of a graph are also considered when a fixed number of edges are removed from the graph. Two novel cost functions are introduced for this purpose. General bounds on these two cost functions are established, and exact values of or tighter bounds on the cost functions are determined for various infinite classes of special graphs. Threshold information is finally established in respect of the number of possible edge removals from a graph before increasing its secure domination number. The notions of criticality and stability are introduced and studied in this respect, focussing on the smallest number of arbitrary edges whose deletion necessarily increases the secure domination number of the resulting graph, and the largest number of arbitrary edges whose deletion necessarily does not increase the secure domination number of the resulting graph. / AFRIKAANSE OPSOMMING: Die dominasiegetal van ’n grafiek is die kardinaalgetal van ’n kleinste deelversameling van die grafiek se puntversameling met die eienskap dat elke punt van die grafiek in die deelversameling is of naasliggend is aan ’n punt in die deelversameling. Hierdie grafiekparameter is sedert die vroeë 1960s uitvoerig bestudeer en vind toepassing in die generiese situasie waar die punte van die grafiek fisiese entiteite voorstel wat tipies geografies verspreid is en doeltreffend gemonitor moet word, terwyl die lyne van die grafiek skakels tussen hierdie entiteite voorstel waarlangs wagte, wat by die entiteite gebaseer is, naasliggende entiteite kan monitor. In die bogenoemde toepassing, bly die wagte bewegingloos by die fisiese entiteite waar hulle geplaas word. In 2005 is hierdie beperking egter verslap met die daarstelling van ’n nuwe dominasie-verwante grafiekparameter, bekend as die sekure dominasiegetal. In hierdie verslapte, dinamiese situasie word elke punt sonder ’n wag deur ’n wag verdedig wat by ’n naasliggende punt geplaas is en wat langs die verbindingslyn na die leë punt kan beweeg om daar ’n bedreiging te neutraliseer, waarna die gevolglike plasing van wagte weer ’n dominasieversameling van die grafiek moet vorm. Die sekure dominasiegetal van ’n grafiek is die kleinste getal wagte wat op die punte van die grafiek geplaas kan word om aan hierdie vereistes te voldoen. Die beginsel van lynverwydering speel ’n belangrike rol in hierdie veralgemeende situasie, omdat daar gevra mag word na die koste, in terme van die addisionele getal wagte wat vereis word, om die kompleks van entiteite wat deur die grafiek gemodelleer word, te beveilig indien ’n aantal lynfalings in die grafiek plaasvind (m.a.w. indien ’n aantal skakels uit die kompleks van entiteite verwyder word, en wagte dus nie meer langs sulke skakels mag beweeg nie). ’n Omvattende literatuurstudie oor sekure dominasie van grafieke word in hierdie verhandeling gedoen. Beskrywings van verwante, veralgemeende verdedigingsparameters in grafiekteorie word ook gegee. Die klasse van grafieke met sekure dominasiegetal 1, 2 of 3 word gekarakteriseer en ’n resultaat oor die getal verdedigers in enige kleinste sekure dominasieversameling van ’n grafiek sonder endpunte word daargestel, waarna daar getoon word dat die beslissingsprobleem onderliggend aan die berekening van die sekure dominasiegetal van ’n arbitrêre grafiek NP- volledig is. Twee eksponensiële-tyd algoritmes en ’n binêre programmeringsformulering word vir die bepaling van die sekure dominasiegetal van ’n arbitrêre grafiek daargestel, terwyl ’n lineêre algoritme vir die berekening van die sekure dominasiegetal van ’n arbitrêre boom ontwerp word. Die praktiese doeltreffendhede van hierdie algoritmes word vir klein grafieke met mekaar vergelyk. Die kleinste en groostste toename in die sekure dominasiegetal van ’n grafiek word ook oorweeg wanneer ’n vaste getal lyne uit die grafiek verwyder word. Twee nuwe kostefunksies word vir hierdie doel daargestel en algemene grense word op hierdie kostefunksies vir arbitrêre grafieke bepaal, terwyl eksakte waardes van of verbeterde grense op hierdie kostefunksies vir verskeie oneindige klasse van spesiale grafieke bereken word. Drempelinligting word uiteindelik bepaal in terme van die moontlike getal lynverwyderings uit ’n grafiek voordat die sekure dominasiegetal daarvan toeneem. Die konsepte van kritiekheid en stabiliteit word in hierdie konteks bestudeer, met ’n fokus op die kleinste getal arbitrêre lynfalings wat noodwendig die sekure dominasiegetal van die gevolglike grafiek laat toeneem, of die grootste getal arbitrêre lynfalings wat noodwendig die sekure dominasiegetal van die gevolglike grafiek onveranderd laat.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Business-to-business services relating to physical asset management are playing an increasingly important role in industry. This is in the midst of the current pressures which asset owning organisations are experiencing in realising optimal value from their assets. The pursuit of understanding and complying with asset management standards such as ISO 55000 as well as the potential value to be gained from successful and sustainable business relationships contributes towards the importance of these services. The problem is that there is little or no evidence regarding the critical success factors for collaborating successfully in asset management services. The study identi es these critical success factors and demonstrates how the factors can di er between role players, industries, global regions and service types. A decision support model is developed providing the asset management community with access to the critical success factors for decision-making purposes. Based on the synthesis from internationally conducted Delphi- and survey studies it is found that the continued and sustained commitment from the asset owning organisation's senior management in support of the asset management service is the most critical factor for a successful asset management service partnership. Open and e ective communication is also highlighted as being critical, while it is important to have a process in place to improve the service continuously. Laboratory and eld testing con rm the validity of the decision support model for facilitating the decision-making process to improve asset management services, and in addition it also formalises the commercial and contracting processes relating to these services. / AFRIKAANSE OPSOMMING: Besigheid-tot-besigheidsdienste met betrekking tot siese batebestuur speel 'n toenemende belangrike rol in die industrie. Dit is te midde van die druk wat batebesittende organisasies tans ondervind om optimale waarde uit hul siese bates te verkry. Die strewe na beter begrip en om te voldoen aan batebestuurstandaarde soos ISO 55000, asook die potensiële waarde wat verkry kan word uit suksesvolle en volhoubare besigheidheidsvennootskappe, dra by tot die belangrikheid van hierdie dienste. Die probleem is daar bestaan min of geen bewyse rakende die kritiese suksesfaktore vir suksesvolle samewerking in batebestuurdienste. Die studie identi seer die kritiese suksesfaktore en toon aan hoe hierdie faktore kan verskil tussen rolspelers, industrieë, wêreldstreke en dienstipes. 'n Besluitnemingsmodel is ontwikkel wat die batebestuurgemeenskap toegang gee tot die kritiese suksesfaktore vir besluitnemingsdoeleindes. Gebaseeer op die sintese van internasionale Delphi- en opnamestudies is daar bevind dat die mees kritieke faktor vir 'n suksesvolle vennootskap in batebestuurdienste die voortgesette en volgehoue toewyding deur die bate-besittende organisasie se senior bestuur, ter ondersteuning van die batebestuurdiens, is. Doeltre ende en openhartige kommunikasie is ook uitgewys as krities, terwyl dit belangrik is om 'n proses te volg om die diens voortdurend te verbeter. Laboratorium- en praktyk toetsing het bevestig dat die besluitnemingsmodel geldig is vir die fasilitering van die besluitnemingsproses om batebestuursdienste te verbeter asook vir die formalisering van die kommersiële en kontraktuele prosesse wat verband hou met hierdie dienste.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Reconfigurable Manufacturing Systems (RMSs) have the ability to reconfigure hardware and control resources at all of the functional and organizational levels. This allows for quick adjustment of production capacity and functionality in response to sudden changes in market or in regulatory requirements. This study evaluates the characteristics and operation of automated reconfigurable assembly lines using discrete event simulation. The assembly line uses a conveyor system which transports pallets to various machines to perform the assembly process. Different conveyor configurations are developed for the same assembly process using Simio simulation software. A part family consisting of five variants are assembled on the same assembly line with a large variation in the production quantities for each product. This requires the assembly system to be able to quickly adjust its functionality and capacity. Multi-objective optimization is performed on the models through the use of a Pareto exhaustive search experiment. The two contradicting objectives used are the throughput rate of the system and the average work in progress, with the aim of maximizing the former and minimizing the latter. From the Pareto exhaustive search experiment, a Pareto front is constructed showing which configuration is preferred under certain operation conditions. However it is concluded that the Pareto front can be tailored to fit the specific needs of the decision maker, depending on what the decision maker is willing to pay. An experiment that evaluates the effect of changing the conveyor speed is performed. It is established that under certain operating conditions, increasing the conveyor speed higher than the ceiling value will not improve the performance of the system. A production scenario was also developed which include different order sizes for each of the five parts of the part family. The configurations have to alter their capacities based on the order sizes to test which system performs the best under these operating conditions. For this experiment, the ramp-up time was of interest but the best system was chosen based on the combination of throughput rate and the average work in progress. From the results of the different experiments, it is recommended to first determine the maximum capacity and the operating logic before choosing one of the configurations. Once this is decided, the information gathered from the experiments can then be tailored for the decision maker to establish the best operating conditions for the chosen con guration. The developed simulation models are used as a Decision Support System for future research on the topic. It is recommended for future research to focus on using Automated Guided Vehicles (AGVs) instead of a conveyor system as transportation method. / AFRIKAANSE OPSOMMING: Herkonfigureerbare Vervaardigingstelsels (HVSs) het die vermoee om alle hardeware en beheer hulpbronne, op alle funksionele en organisatoriese vlakke te herkonfigureer. Dit maak dit moontlik vir vinnige verstellings aan produksie kapasiteit en funksionaliteit, indien daar 'n skielike verandering in die mark of wetgewing is. Hierdie studie evalueer die karakteristieke en werking van outomatiese herkon gureerbare monteerlyne met behulp van diskrete gebeurtenis simulasie. Die monteerlyne gebruik vervoerbande om pallette na verskeie masjiene te vervoer, sodat die parte aanmekaar gesit kan word. Simio simulasie sagteware is gebruik om verskillende vervoerband kon gurasies vir dieselfde monteringsproses te ontwikkel. 'n Part familie van vyf variante word op dieselfde monteerlyn aanmekaargesit. Daar is 'n groot variasie in die produksie hoeveelhede van elk van die vyf variante, dus moet die monteerlyne vinnig die kapasiteit en funksionaliteit kan aanpas. Multi-doelwitoptimering is toegepas op die modelle deur 'n Pareto alomvattende soek eksperiment uit te voer. Die twee teenstrydige doelwitte wat gebruik is, is die deurset tempo van die stelsel asook die gemiddelde werk-in-proses. Die doel is om die deurset tempo te maksimeer en terselfde tyd die gemiddelde werk-in-proses te minimeer. Die Pareto alomvattende soek eksperiment word verder gebruik om 'n Pareto front te skep wat uitwys watter vervoerband kon gurasies verkies word onder sekere bedryfstoestande. Die Pareto front kan egter aangepas word om die spesi eke behoeftes van die besluitnemer te pas. 'n Eksperiment is uitgevoer om die uitwerking van die vervoerbandspoed op die stelsel te toets. Resultate het getoon dat onder sekere bedryfstoestande die werkverrigting van die stelsel nie verbeter indien die spoed 'n maksimum grenswaarde oorskry nie. 'n Eksperiment wat 'n produksie scenario voorstel is ontwikkel waarin die vraag na die vyf part variante gevarieer word. Die vervoerband konfigurasies moet dan die kapasiteit aanpas gebaseer op die vraag na die parte. Die doel van die eksperiment is om te toets watter kon gurasie die beste vaar onder hierdie bedryfstoestande. Die tyd wat dit neem vir die stelsel om weer op dreef te kom na 'n verandering in kapasiteit is ondersoek in hierdie eksperiment, maar die beste stelsel is nog steeds gekies gebaseer op die kombinasie van deurset tempo en die gemiddelde werk-in-proses. Gegewe die resultate van die verskillende eksperimente, word dit voorgestel dat die besluitnemer eers die maksimum kapasiteit en die bedryfstoestande vasstel, voordat 'n vervoerband kon gurasie gekies word. Sodra dit besluit is, kan die inligting wat tydens die eksperimente ingesamel is, aangepas word om die beste bedryfstoestande vir die kon gurasie wat gekies is, vas te stel. Die simulasie modelle wat ontwikkel is word gebruik as 'n besluitnemingsondersteuningstelsel vir toekomstige navorsing oor die onderwerp. Dit word voorgestel dat toekomstige navorsing die moontlikheid van geoutomatiseerde begeleide voertuie (GBV), in plaas van vervoerbande as vervoermiddel, ondersoek.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The aerospace industry actively pursues innovation, especially in materials and their use in new applications, to improve their aircraft as well as their competitive position. Ti-6Al-4V has been available now for more than 50 years. Yet, in the new generation of aircraft using structural composites, a dramatic increase in the proportion of Ti-6Al-4V will be seen along with emerging application in automotive and chemical industries. This material possesses superior material properties compared to conventional materials such as steel and aluminium, although it is at the expense of machinability. Researchers are therefore actively searching for improved cutting technologies to improve production rates for Ti-6Al-4V. At higher cutting speeds than the industry norm of 60 - 90 m/min, machining becomes a challenge, resulting in low productivity on titanium parts. The limiting factor in the machining of Ti-6Al-4V is high tool temperatures of the order of 1000oC, caused by its resistance to absorb heat and good mechanical strength at elevated temperatures. The result is extreme temperatures that are concentrated on the cutting edge of the tool. The challenge to improve the tool life is therefore focused on removing heat from the insert. Liquid nitrogen was identified as a good candidate as coolant with the additional advantage of being environmentally friendly. The research presented investigates the use of a gravity feed enclosed liquid nitrogen cooling system to improve the tool life of the cutting inserts. The liquid nitrogen is contained on the insert rake face by means of a tool cap. To improve the effectiveness of the cooling method, a polycrystalline diamond (PCD) insert was used. This insert has a considerably higher thermal conductivity that aids in cooling the cutting edge. Tungsten carbide inserts are used for benchmark testing. The round tungsten carbide inserts with conventional cooling performed exceptionally well for machining titanium compared to square inserts, yielding exceptional tool life improvements while significantly increasing the material removal rate. Positive results were recorded with the liquid nitrogen cooling system when used with the polycrystalline diamond cutting insert. A number of far reaching performance issues are identified relating to the design of the tool cap that hindered clear scientific outputs. From a research perspective, the project makes a contribution to the knowledge base in this field. Additionally a new approach in cooling was investigated, resulting in clear indications of design changes required. / AFRIKAANSE OPSOMMING: Die lugvaart industrie streef aktief innovasie na, veral op die gebied van materiale en hul gebruike, om hul vliegtuie en kompeterende posisie in die mark te verbeter. Ti-6Al-4V is al vir meer as 50 jaar beskikbaar. ‘n Drastiese verhoging in die aanvraag na Ti-6Al-4V deur die lugvaart, motor en chemiese industrieë word verwag wanneer die volgende geslag vliegtuie wat koolstofvesel as strukturele materiaal begin gebruik, in produksie gaan. Die materiaal het beter materiaaleienskappe as konvensionele materiale soos staal en aluminium, maar dit kom egter teen die prys van masjieneerbaarheid. Ti-6Al-4V se masjienering bo die industrie norm van 60 – 90m/min is ‘n groot uitdaging. Navorsers soek daarom deurentyd na verbeterde sny tegnologieë om die produksie tempo van Ti-6Al-4V te verbeter. Die beperkende faktor vir Ti-6Al-4V masjienering is die temperatuur wat genereer word. Die weerstand van die materiaal om hitte te absorbeer en sy goeie meganiese eienskappe veroorsaak dat temperature in die beitel 1000oC bereik. Hierdie temperature word egter op die snykant van die beitel gekonsentreer. Die uitdaging is dus om hierdie temperature in die beitel te beheer. Vloeibare stikstof is geïdentifiseer as ‘n goeie kandidaat vir verkoeling met die bykomende voordeel dat dit omgewingsvriendelik is. Die navorsing wat hier uiteengesit word, ondersoek die gebruik van ‘n geslote kamer beitelverkoelingstelsel wat deur gravitasie met vloeibare stikstof voorsien word om die beitel leeftyd te verbeter. Die oppervlak van die beitel word in hierdie konsep direk aan die vloeibare stikstof blootgestel. Om die effektiwiteit van die stelsel te verbeter word van PCD beitels gebruik gemaak. Die beitel se verbeterde hittegeleidingsvermoë help om die beitel se snykant koel te hou. Tungstenkarbied beitels word gebruik om ‘n standaard te stel vir eksperimentele analise. Die ronde tungstenkarbied beitels en konvensionele verkoeling het verstommend goed presteer vir Ti-6A-4V masjienering in vergelyking met vierkantige beitels. Die materiaalverwyderingstempo is aansienlik verhoog sonder om die beitel se leeftyd in te boet. Positiewe resultate is waargeneem met die vloeibare stikstof sisteem saam met die PCD beitels. ‘n Aantal verreikende uitdagings is geïdentifiseer wat suiwer wetenskaplike afleidings bemoeilik. Hierdie probleme kan almal aan die ontwerp van die toerusting toegeskryf word. Die werk lewer egter steeds ‘n bydrae tot die kennis in die veld. ‘n Bykomende benadering vir verkoeling is ondersoek wat duidelik ontwerp-veranderings aandui.

Thesis (MScEng (Industrial Engineering))--Stellenbosch University, 2008. / This thesis reports on a research project conducted at Stellenbosch University, focusing on the field of information management, and contributing to the development of an approach for structuring information in such a manner that context becomes apparent, which on its part assists persons (and groups of persons) in selecting useful information from a larger whole, given a certain context. This document is composed of three general sections. The first section is a literature study focusing on the following topics: (1) Information overload: The amount of information in the world, as well as its rate of generation is discussed, together with the notion of information overload, its causes, symptoms and possible solutions. (2) Information utilisation in organisations: General concepts concerning the utilisation of information in organisations are discussed, together with the manners in which organisations fail in efficiently utilising information, but also some examples where organisations have succeeded. (3) Information modelling: Various well-known information modelling approaches currently employed to improve information utilisation are discussed and compared. It is however mentioned that none of these approaches are sufficiently general, flexible and simple enough to assist typical organisational knowledge workers in efficiently interacting with information. The second section of this thesis focuses on the conceptual framework information modelling approach currently being investigated at Stellenbosch University as a means for improving the information utilisation efficiency of organisational knowledge workers. The basic concepts of the approach are discussed, and it is compared with the more well-known information modelling approaches mentioned in the literature study. The research being conducted on the approach is further briefly discussed, which includes the purpose of this thesis (which is the development of a methodology for conceptual framework implementation in organisations), the research method followed, and the thesis hypothesis, which is: Information represented by a conceptual framework implemented through the use of the developed conceptual framework implementation methodology, offer a truthful view on information found in an organisation. The methodology developed is subsequently discussed in terms of its phases and activities, each of which is discussed in terms of its description, the rationale behind and prerequisites of its execution, details of the manner of its execution, and the eventual outputs thereof. The final section of this thesis provides information on the validation of the conceptual framework implementation methodology described in the previous section, which were done in two parts. A theoretical validation was done through a comparison of the developed methodology with existing methodologies for the implementation of other information modelling approaches. A practical validation was also done through two case studies by which conceptual frameworks were implemented at two separate organisations. The document is finally concluded through a summary of the contents of this thesis, the outcome of the hypothesis test, and some closing remarks.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The various applications of Information and Communication Technologies (ICTs) in healthcare are increasingly effective to improve the cost-effectiveness and quality of healthcare service delivery. Telemedicine is such an application, using ICTs to provide health services over a distance. Since 1997, the South African Department of Health has invested large amounts of capital to implement telemedicine systems in South Africa. Unfortunately, telemedicine programs have had little success since, leading to many workstations standing dormant. Telemedicine implementation decision making that is based on insufficient evidence is identified as one of the underlying problems that cause telemedicine programs to fail. It is proposed that implementation decisions should be based on quantifiable evidence regarding the potential benefits of telemedicine. A decision support system is developed that can be used to quantify potential benefits and plan telemedicine implementation programs accordingly. The decision support system is modelled and demonstrated using data from the Eastern Cape public health sector. The first phase of the system guides decision makers to identify potential telemedicine benefits as well as data sources that can be used to measure these benefits. The system is scoped to focus on the application of telemedicine to support patient referrals between hospitals. Data sources are considered accordingly, with electronic health record (EHR) data proving to be a feasible primary source for needs assessments, however limiting the benefits that can be quantified. The analysis of the needs assessment is included in the second phase of the decision support system. Data are extracted, transformed and loaded into a data warehouse from where it can be analysed. The system includes three analysis steps to: map referral patterns, analyse potential benefits of telemedicine programs and determine cost-effective telemedicine solutions by allocating equipment at different hospitals. Analysis techniques used in the system include Pareto analysis, economic analysis, linear programming and the use of a genetic algorithm. It is proposed that the potential benefit results and equipment allocation algorithm be used to plan telemedicine programs for continuous evaluation. The final phase of the system therefore guides decision makers to use the results for implementation planning as well as evaluability assessments, for future management and evaluation of telemedicine programs. The decision support system is validated using patient referral data from the Western Cape public health sector. The case study proved that the system is applicable to the real-world and could be a valuable tool for decision makers to base telemedicine implementation planning on quantifiable evidence. The limitation on size and quality of both the Eastern Cape and Western Cape data sets, caused that the full potential of the system could not be demonstrated and validated. It is recommended that the quality standards of EHR referral reports be improved, to ensure more accurate benefit results. Future work is recommended to include qualitative needs assessments in the scope of the decision support system, hereby increasing the amount of benefits to be assessed. Although it is expected that the developed system is capable to support even better resolution decisions with more detailed data sets, the system developed in this study proved already adequate for improved implementation decision making. This could lead to higher success rates of telemedicine programs and ultimately better quality healthcare for all. / AFRIKAANSE OPSOMMING: Die verskillende toepassings van Informasie en Kommunikasie Tegnologie (IKT) in gesondheidsorg, speel ʼn rol in toenemende doeltreffendheid om die koste-effektiwiteit en kwaliteit van gesondheidsorg dienslewering te verbeter. Tele-geneeskunde is een van hierdie toepassings, wat IKT gebruik om gesondheidsdienste oor ʼn afstand te kan voorsien. Die Suid-Afrikaanse Departement van Gesondheid belê sedert 1997, groot bedrae kapitaal in die implementering van tele-geneeskunde stelsels, in Suid-Afrika. Ongelukkig het tele-geneeskunde programme min sukses behaal sedertdien, wat veroorsaak dat vele werkstasies dormant is. Die basering van implementeringsbesluite op onvoldoende getuienis, is geïdentifiseer as een van die onderliggende probleme wat veroorsaak dat tele-geneeskunde programme misluk. Daar word voorgestel dat implementeringsbesluite gebaseer moet word op kwantifiseerbare getuienis ten opsigte van die potensiële voordele van telemedisyne. ʼn Besluitnemingsondersteuning stelsel is ontwikkel wat gebruik kan word om die potensiële voordele te kwantifiseer en dienooreenkomstig implementering van tele-geneeskunde programme te beplan. Die stelsel is gemodelleer en gedemonstreer aan die hand van data uit die Oos-Kaap publieke gesondheidsektor. Die eerste fase van die stelsel begelei besluitnemers om potensiële voordele van telegeneeskunde, sowel as data-bronne wat gebruik kan word om hierdie voordele te meet, te identifiseer. Die stelsel is beperk tot ʼn fokus op die ondersteuning wat tele-geneeskunde aan hospitaal pasiënt verwysingstelsels, kan bied. Data bronne is dienooreenkomstig oorweeg: elektroniese mediese rekords (EMR) word erken as ʼn gunstige primêre databron, maar veroorsaak egter beperkings op die aantal voordele wat gekwantifiseer kan word. Die behoeftebepaling word uitgevoer in die tweede fase van die besluitnemingsondersteuning stelsel. Data is onttrek, getransformeer is en gelaai in 'n data stoor, vanwaar dit ontleed kan word. Die stelsel sluit drie analisestappe in: verwysingspatroon analise, berekening van potensiële voordele vir tele-geneeskunde programme en die bepaling van koste-effektiewe oplossings deur toekenning van toerusting by verskillende hospitale. Die analise tegnieke wat in die stelsel gebruik word, sluit die volgende in: Pareto analise, ekonomiese analise, lineêre programmering en 'n genetiese algoritme. Die gebruik van potensiële voordeel resultate en die toerusting toekenning algoritme word voorgestel vir die beplanning vir deurlopende evaluering in tele-geneeskunde programme. Die finale fase van die stelsel is gestruktureer, om besluitnemers te begelei in die gebruik van analise resultate, vir implementering beplanning sowel as evalueerbaarheid studies, wat sodoende deurlopende evaluering en bestuur van tele-geneeskunde programme sal verbeter.Die besluitnemingsondersteuning stelsel is gevalideer deur pasiënt verwysings data van die Wes-Kaap publieke gesondheidsektor, te gebruik. Die gevallestudie het bewys dat die stelsel toepaslik is in die werklike wêreld en kan as ʼn waardevolle hulpmiddel vir besluitnemers dien om tele-geneeskunde implementering beplanning op kwantifiseerbare bewyse te baseer. Die beperkings op die grootte en gehalte van beide die Oos-Kaap en Wes-Kaap datastelle het veroorsaak dat die stelsel nie tot sy volle reg gedemonstreer en gevalideer kon word nie. Verbeterings in kwaliteit standaarde van EMR verwysing data word aanbeveel om meer akkurate resultate te bekom. Verdere studies wat die byvoeg van kwalitatiewe meetings in die stelsel ondersoek, sal die omvang van potensiële voordele verbeter en dus die algehele waarde van die stelsel verbeter. Alhoewel die ontwikkelde stelsel in staat is om beter resolusie besluite te kan ondersteun met meer gedetailleerde data, is dit bewys dat die huidige stelsel reeds voldoende is om besluitneming te verbeter. Beter besluitneming gevolglik lei tot hoër sukseskoerse van tele-geneeskunde programme en uiteindelik verbeterde gehalte gesondheidsorg vir almal.