No / The marginal cost approach for the analysis of repair/replacement models was introduced by Berg in 1980 and has since been applied to many maintenance policies of various complexity. All models hitherto analysed in the literature by the marginal cost approach have one single decision variable only, this being, typically, the age of the current item at the time of ordering or replacement. This paper is concerned with the extension of the marginal cost technique to maintenance policies with several decision variables. After addressing the general framework appropriate for the multi-parameter case, we exemplify the workings of the technique by analysing a two-variable maintenance model involving replacement and minimal repair. We demonstrate that the marginal cost approach is an attractive and intuitively appealing technique also for models with several decision variables. Just as in the single-parameter situation, the approach is amenable to economic interpretation, a welcome feature for users of maintenance models with a prime interest in its economic (rather than its mathematical) aspects. As an added bonus of the marginal cost approach, in our example, some otherwise necessary tools from the theory of stochastic processes are dispensable.

The various components of financial structure management are usually discussed in isolation with little concern for the other components. A unified model of financial structure management bridging these components has not yet been developed. This dissertation seeks to establish such an underpinning by combining Miller and Orr's cash management model with contemporary corporate finance theory, and is able to address a wide range of questions while retaining a comprehensible format. I simulate the proposed strategy to show the consequences of implementation, and to provide hypotheses about the behavior of financial variables characterizing the firm as a result of implementing this strategy. / Ph. D.

This dissertation explores the role of science and technology in democracy and the use of cost-benefit analysis (CBA) through an illustrative case on a uranium mining controversy in the US state of Virginia. Arguably, traditional STS scholarship has primarily served what we might call an unmasking function by working to expose political, cultural, gender, corporate, and other factors that get masked by the cultural authority of scientific expertise. Following the lead of other STS scholars seeking to move beyond an unmasking-only mode of scholarship, this dissertation offers a novel take on the relationship between expertise and public controversy over technoscience by suggesting that cost-benefit analysis might serve a beneficial pro-democratic ritual role. To explore this question of the role played by expertise and what we might learn and recommend from approaching CBA as a democratic ritual, I consider the case of a uranium mining and milling controversy in Virginia. This controversy surfaced in two distinct historical moments and prominently featured technical studies utilizing expert predictive methods. I analyze these texts from the perspective of the sociopolitical ritual theory developed in the dissertation and then suggest a set of recommendations regarding how we might humanize and deploy CBA within the context of enhancing rituals that serve to maintain liberal democratic political imaginaries. / Ph. D. / This dissertation explores the role of science and technology in democracy and the use of cost-benefit analysis (CBA) through an illustrative case on a uranium mining controversy in the US state of Virginia. Ultimately, this research offers a novel take on the relationship between expertise and public controversy over technical and scientific projects by suggesting that cost-benefit analysis might serve a beneficial ritual role. After articulating a conceptual framework and analyzing a series of technical studies, a set of recommendations regarding the use of cost-benefit analysis within the context of democratic policy-making is articulated.

No / Production of titanium is challenging and expensive due to the energy energy-intensive and time-consuming processes used at present. Current commercial production method reduces titanium tetrachloride with magnesium or sodium to produce titanium metal. Several researchers have attempted electro-deposition of titanium from ionic solutions but have faced difficulties in eliminating multivalent titanium ions and highly reactive dendrite products. In this paper, we report, for the first time, the solid-solid phase transformation of titanium dioxide with calcium metal, under suitable conditions, to form solid titanium metal powder (>98% pure) without any oxygen impurity. On phase characterisation, it was found that homogeneous alpha-titanium was produced. The paper also includes the results and interpretations obtained using quantitative analysis, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and phase diagram. The process is simple, green, rapid and cheap compared to the existing methods.

Carbon tax, increased reactive power charges, tariff increases and the Energy Conservation Scheme (ECS) are some of the worrying electricity cost risks faced by large South African industries. Some of these proposed cost risks are not enforced as yet, but once approved could threaten company financial viability and thousands of jobs. Managing multiple cost risks associated with electricity consumption at several mines can be laborious and complex. This is largely due to circumstantial rules related to each potential electricity cost risk and unique mine characteristic. To limit the electricity cost risks for a mining company, clear strategies and focus areas need to be identified. No literature was found that provides a simplified integrated electricity cost risk and mitigation strategy for the South African gold mining industry. Previous studies only focused on a single mine or mining subsystem. Literature pertaining to potential risks is available, however the exact impact and mitigation on the gold mining industry has yet to be determined. The aim of this study is to accurately predict the impact of electricity cost risks and identify strategies that could alleviate their cost implications. Electricity consumption and installed capacities were used to benchmark mines and categorise them according to investigated risks. The benchmarked results provided an accurate starting point to identify best practices and develop electricity cost saving strategies. This study will highlight the additional benefits that can be obtained by managing electricity usage for a group of mines or mining company. Newly developed models are used to quantify savings on pumping, compressed air and cooling systems. To manage and report on the potential risks and mitigation, an ISO 50001 based energy management system was developed and implemented. The applied and developed models can also be adjusted to review and manage the potential cost risks on other types of mines. Derived risk and mitigation models were further used to quantify the impact on one of the largest gold mining companies in South Africa. These models indicate a potential annual price increase of 12%, while mitigation strategies could reduce the electricity consumption by more than 7%. Mitigation savings resulted from proposed projects as well as behavioural change-induced savings due to improved management. Over a five-year period the projects identified could result in electricity costs savings of between R675-million and R819-million. / PhD (Electrical Engineering), North-West University, Potchefstroom Campus, 2014

Carbon tax, increased reactive power charges, tariff increases and the Energy Conservation Scheme (ECS) are some of the worrying electricity cost risks faced by large South African industries. Some of these proposed cost risks are not enforced as yet, but once approved could threaten company financial viability and thousands of jobs. Managing multiple cost risks associated with electricity consumption at several mines can be laborious and complex. This is largely due to circumstantial rules related to each potential electricity cost risk and unique mine characteristic. To limit the electricity cost risks for a mining company, clear strategies and focus areas need to be identified. No literature was found that provides a simplified integrated electricity cost risk and mitigation strategy for the South African gold mining industry. Previous studies only focused on a single mine or mining subsystem. Literature pertaining to potential risks is available, however the exact impact and mitigation on the gold mining industry has yet to be determined. The aim of this study is to accurately predict the impact of electricity cost risks and identify strategies that could alleviate their cost implications. Electricity consumption and installed capacities were used to benchmark mines and categorise them according to investigated risks. The benchmarked results provided an accurate starting point to identify best practices and develop electricity cost saving strategies. This study will highlight the additional benefits that can be obtained by managing electricity usage for a group of mines or mining company. Newly developed models are used to quantify savings on pumping, compressed air and cooling systems. To manage and report on the potential risks and mitigation, an ISO 50001 based energy management system was developed and implemented. The applied and developed models can also be adjusted to review and manage the potential cost risks on other types of mines. Derived risk and mitigation models were further used to quantify the impact on one of the largest gold mining companies in South Africa. These models indicate a potential annual price increase of 12%, while mitigation strategies could reduce the electricity consumption by more than 7%. Mitigation savings resulted from proposed projects as well as behavioural change-induced savings due to improved management. Over a five-year period the projects identified could result in electricity costs savings of between R675-million and R819-million. / PhD (Electrical Engineering), North-West University, Potchefstroom Campus, 2014

Fires within the built environment are a fact of life and through design and the application of the building regulations and design codes, the risk of fire to the building occupants can be minimised. However, the building regulations within the UK do not deal with property protection and focus solely on the safety of the building occupants. This research details the statistical analysis of the UK Fire and Rescue Service and the Fire Protection Association's fire incident databases to create a loss model framework, allowing the designers of a buildings fire safety systems to conduct a cost benefit analysis on installing additional fire protection solely for property protection. It finds that statistical analysis of the FDR 1 incident database highlights the data collection methods of the Fire and Rescue Service ideally need to be changed to allow further risk analysis on the UK building stock, that the statistics highlight that the incidents affecting the size of a fire are the time from ignition to discovery and the presence of dangerous materials, that sprinkler activations may not be as high as made out by sprinkler groups and that the activation of an alarm system gives a smaller size fire. The original contribution to knowledge that this PhD makes is to analyse the FDR 1 database to try and create a loss model, using data from both the Fire Protection Association and the Fire and Rescue Service.

Ensuring the resilience of self-adaptive systems used in critical infrastructure systems is a concern as their failure has severe societal and financial consequences. The current trends in the growth of the scale and complexity of society's workload demands and the systems built to cope with these demands increases the anxiety surrounding service disruptions. Self-adaptive mechanisms instill dynamic behavior to systems in an effort to improve their resilience to runtime changes that would otherwise result in service disruption or failure, such as faults, errors, and attacks. Thus, the evaluation of a self-adaptive system's resilience is critical to ensure expected operational qualities and elicit trust in their services. However, resilience benchmarking is often overlooked or avoided due to the high cost associated with evaluating the runtime behavior of large and complex self-adaptive systems against an almost infinite number of possible runtime changes. Researchers have focused on techniques to reduce the overall costs of benchmarking while ensuring the comprehensiveness of the evaluation as testing costs have been found to account for 50 to 80% of total system costs. These test suite minimization techniques include the removal of irrelevant, redundant, and repetitive test cases to ensure that only relevant tests that adequately elicit the expected system responses are enumerated. However, these approaches require an exhaustive test suite be defined first and then the irrelevant tests are filtered out, potentially negating any cost savings. This dissertation provides a new approach of defining a resilience changeload for self-adaptive systems by incorporating goal-oriented requirements engineering techniques to extract system information and guide the identification of relevant runtime changes. The approach constructs a goal refinement graph consisting of the system's refined goals, runtime actions, self-adaptive agents, and underlying runtime assumptions that is used to identify obstructing conditions to runtime goal attainment. Graph theory is then used to gauge the impact of obstacles on runtime goal attainment and those that exceed the relevance requirement are included in the resilience changeload for enumeration. The use of system knowledge to guide the changeload definition process increased the relevance of the resilience changeload while minimizing the test suite, resulting in a reduction of overall benchmarking costs. Analysis of case study results confirmed that the new approach was more cost effective on the same subject system over previous work. The new approach was shown to reduce the overall costs by 79.65%, increase the relevance of the defined test suite, reduce the amount of wasted effort, and provide a greater return on investment over previous work by a factor of two.

Thesis (MBA (Business Management))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: South Africa is on the verge of major changes in the private medical sector. The government’s planned National Health Insurance has far reaching implications for all role players in the industry, as well as for the general public. This paper looks at the changes that have been made since the ANC government came to power in 1994 and then continues to look at possible models for the new National Health Insurance plan. A proposal on practicing cost-effective cardiology within this new system is made. The data of a pilot project between a private service provider and a managed healthcare company is analysed as a basis of this discussion. / AFRIKAANSE OPSOMMING: Suid-Afrika se mediese bedryf staan op die vooraand van groot veranderinge. Die regering se beplande Nasionale Gesondheidsplan het verreikende implikasies vir alle rolspelers in die bedryf, sowel as die algemene man op straat. Die dokument kyk oorsigtelik na die veranderinge wat ondergaan is sedert die ANC regering aan bewind gekom het in 1994 en gaan daarna voort om na moontlike opsies te kyk hoe die nuwe gesondheidsmodel daarna gaan uitsien. Voorstelle word gemaak oor hoe privaat kardiologie in die nuwe sisteem koste-effektief beoefen kan word. ‘n Lootsprojek van ‘n privaat diensverskaffer en ‘n bestuurde gesongheidsorg maatskappy se data word ontleed as basis vir die bespreking.

published_or_final_version / Urban Planning and Environmental Management / Doctoral / Doctor of Philosophy