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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Eskom nuclear generation : risk mitigation through quality management development of small suppliers

Van Reenen, Olaf Pieter January 2009 (has links)
Thesis (MTech (Quality)--Cape Peninsula University of Technology, 2009 / There is a South African Government initiative to use State-owned Enterprises (SOE’s) to roll out a programme for the development and stimulation of local small businesses in South Africa. The state has requested SOE’s to set targets on a voluntary basis to increase trade with small businesses, with the purpose of developing small enterprises to eventually enhance skills transfer, training and employment. However, when large customers such as Eskom Nuclear Generation require ISO certification as a prerequisite for a supplier to provide goods and/or services to them, most small businesses are unable to comply. The requirement of ISO9000 compliance inhibits the ability of most small businesses to compete with their larger counterparts. Small businesses constitute as much as 90% of most world economies. They have many advantages to offer customers, such as a high level of flexibility, innovation and responsiveness to customer needs. These attributes can introduce healthy competition to the supply chain. Small businesses, by their very nature experience more risks, such as a higher vulnerability to volatile market forces and skills loss. In addition, they are generally less specialised. They are under continuous competitive pressure, and are generally not able to provide assurance of a sustainable product over a longer period. Although there is an imperative to develop and use small suppliers, they introduce higher risk to the supply chain. The primary research objective of this dissertation is to develop a robust model to identify risks inherent to small businesses, and to propose measures to mitigate such risks. A classification of problems with small suppliers that have occurred at Koeberg Nuclear Power Station over a period of 3 years (from June 2005 to May 2008), will form the basis of the research methodology. The anticipated findings of the research include the following. _ Several common critical issues of failure will be identified in the internal processes of small suppliers, with variations between types of suppliers, which will indicate which elements within the context of ISO9000 can be applied to address shortcoming in the suppliers’ processes. _ A matrix will be compiled from this by which the customer can identify the type of supplier, the types of risks inherent to that supplier, and which elements of ISO9000 the customer should insist upon to be adopted into an elementary quality management system of that small supplier. This should be executed as part of a larger supplier development programme.
22

Short term load forecasting using quantile regression with an application to the unit commitment problem

Lebotsa, Moshoko Emily 21 September 2018
MSc (Statistics) / Department of Statistics / Generally, short term load forecasting is essential for any power generating utility. In this dissertation the main objective was to develop short term load forecasting models for the peak demand periods (i.e. from 18:00 to 20:00 hours) in South Africa using. Quantile semi-parametric additive models were proposed and used to forecast electricity demand during peak hours. In addition to this, forecasts obtained were then used to nd an optimal number of generating units to commit (switch on or o ) daily in order to produce the required electricity demand at minimal costs. A mixed integer linear programming technique was used to nd an optimal number of units to commit. Driving factors such as calendar e ects, temperature, etc. were used as predictors in building these models. Variable selection was done using the least absolute shrinkage and selection operator (Lasso). A feasible solution to the unit commitment problem will help utilities meet the demand at minimal costs. This information will be helpful to South Africa's national power utility, Eskom. / NRF
23

Probabilistic solar power forecasting using partially linear additive quantile regression models: an application to South African data

Mpfumali, Phathutshedzo 18 May 2019 (has links)
MSc (Statistics) / Department of Statistics / This study discusses an application of partially linear additive quantile regression models in predicting medium-term global solar irradiance using data from Tellerie radiometric station in South Africa for the period August 2009 to April 2010. Variables are selected using a least absolute shrinkage and selection operator (Lasso) via hierarchical interactions and the parameters of the developed models are estimated using the Barrodale and Roberts's algorithm. The best models are selected based on the Akaike information criterion (AIC), Bayesian information criterion (BIC), adjusted R squared (AdjR2) and generalised cross validation (GCV). The accuracy of the forecasts is evaluated using mean absolute error (MAE) and root mean square errors (RMSE). To improve the accuracy of forecasts, a convex forecast combination algorithm where the average loss su ered by the models is based on the pinball loss function is used. A second forecast combination method which is quantile regression averaging (QRA) is also used. The best set of forecasts is selected based on the prediction interval coverage probability (PICP), prediction interval normalised average width (PINAW) and prediction interval normalised average deviation (PINAD). The results show that QRA is the best model since it produces robust prediction intervals than other models. The percentage improvement is calculated and the results demonstrate that QRA model over GAM with interactions yields a small improvement whereas QRA over a convex forecast combination model yields a higher percentage improvement. A major contribution of this dissertation is the inclusion of a non-linear trend variable and the extension of forecast combination models to include the QRA. / NRF
24

The perceived visual impacts and attitudes of the Grahamstown community towards the Waainek Wind-Farm

Cruickshank, Kyle Mark January 2014 (has links)
Renewable energy has become an important feature of most modern economies with clean and non-exhaustible sources of power being given a greater significance. Wind energy is one of the favoured renewable, as it is (2013) generally the cheapest and most mature technology available for commercial use. The South African government, as outlined by the Department of Energy's Integrated Resource Plan (IRP), aims to install 5 GW (Gigawatts) of wind energy by 2020. However, South Africa has had little experience in the wind energy industry which is limited to two projects, Klipheuwel (2002) and Darling (2008). Much effort has been dedicated to calculating balance sheet costs, which carries uncertainty due to the high reliance on country specific and site specific variables. An aspect which deserves more attention, and is often ignored, is the public‟s attitudes towards local wind farm developments, which have been known to "make or break" a project during the planning stages. Public backlashes have mostly been concerned with the visual "intrusiveness" of wind farms in the landscape. Detrimental effects on scenery, while seemingly innocuous, are acknowledged as being the single largest barrier to successful wind farm development. Individuals within an area become sentimentally attached to their surroundings, where significant rapid changes in the landscape are viewed as "damage". Economics recognises such declines in scenic resources as market failures, where an externalised cost is passed on to the public and is often not accounted for by private parties responsible for the liability. The primary objective therefore was to measure the magnitude of the visual impact, caused by the Waainek Wind Farm, on the Grahamstown community. Conventional NIMBY¹ (not in my back yard) reasoning, which seeks to explain local wind farm resistance, has attracted criticism with regard to its simplistic approach to wind farm problem identification. Contemporary arguments propose that NIMBY is a poor explanation for the trouble experienced on the local level because it groups problems into one all-encompassing term, leaving much of the discontent unexplained. Instead, the NIMBY explanation is really a broad set of unattended problems, largely resulting from the unsound practices present in the public participation process. Insufficient community involvement and disparities in the negotiation power structures have become the recent focus in wind farm literature. Essentially, these disparities force opposition groups to select factors which may seem more serious to developers, leading to ineffective remedial measures because the core underlying problems are not being remedied. Thus these considerations formed an additional area of investigation. No NIMBY effect was found for the Grahamstown community, as support for both the local and general level was roughly 80%. The public participation process on the other hand revealed that while many found the practices of the developer to be unfair, attitudes towards the wind farm were not adversely affected, especially for the lower income Grahamstown East areas. While the public participation process in this instance did not have any effect on people’s attitudes, careful inspection of the circumstances need to be given. Wind farms are new to South Africa, where the novelty and benefits are the focus of enthusiasm. Job opportunities as well as clean energy are positive drivers for attitudes; however given time, once the anticipation for wind farms dulls, real problems may be revealed. Thus it is crucial to implement good practice procedures during the public participation process, especially when national adoption rates of wind energy are low. Early implementation of an effective public participation process system will ensure that when major problems do arise in future projects, experience and institutional processes would have had ample opportunity to evolve appropriately over a period of time. The double bounded Contingent Valuation Method was used to value the impact of the wind farm on the Waainek scenery through a hypothetical scenario based procedure which presented pictures of the landscape before and after the wind farm had been installed. Based on the perceived impact of the wind farm, respondents were asked their Willingness to Pay to relocate the development, based solely on visual impacts. Learning design Contingent Valuation (Bateman et al., 2008) is a novel technique employed to familiarize respondents with the hypothetical market institution as well as the scenic goods being valued. Average Willingness to Pay was found to be R67 per month, with a final total monthly negative visual impact of R104,000 to R121,000 per month for the entire Grahamstown community. Grahamstown Central (middle-high income) residents were more likely to pay than Grahamstown East (low-middle income) East residents because of socio-economic differences present in each area. A ranking exercise determined that while negative visual impacts are present, the overall benefits derived from the wind farm are potentially much higher. Additionally, positive scenic improvements were found, but were not measured due to time constraints, and would have worked to reduce the net visual impact of the Waainek Wind Farm. ¹Problem where individuals support the general concept of wind power, but when it comes to local implementation, opposition to the development arises within the same group.
25

Evaluation of the suitably of proposed site for construction of photovoltaic solar facility at Kakamas in the Northern Cape of South Africa

Tshilate, Lindelani 18 May 2019 (has links)
MESMEG / Department of Mining and Environmental Geology / Solar energy development is experiencing significant growth due to national interest in increasing energy efficiency, reducing dependence on fossil fuels, increasing domestic energy production, and curbing greenhouse gas emissions. Northern Cape is generally known to be one of the preferred areas for the generation of solar energy in South Africa, and even in the world, due to its abundant solar radiation. Although this area has abundant potential for solar power generation, not all the areas are suitable for construction of solar plant facilities especially those that are prone to sand storm and dust accumulation. Consequently, site evaluation is very crucial for planning, design and construction of the solar facility. The main objective of this study was to determine the suitability of a proposed site at Kakamas in the Northern Cape for construction of a photovoltaic solar facility. The specific objectives of this research were to assess and establish all the geotechnical aspects that may have an impact on the development of the site, to explore the surface conditions at the proposed site and to establish the soil properties and comment on the use of the on-site soils in the construction of the solar facility. Other specific objectives included to determine the variability of ground conditions and effects of such variability on the proposed development and to provide foundation recommendations for the design and construction of the solar facility. In order to obtain this information, methods such as desktop studies, geological survey, soil survey, magnetic survey and soil profiling were employed to obtain information about the geotechnical aspects of the study area and properties of the on-site soil. Field tests such as cone penetration and resistivity survey and laboratory tests such as foundation indicator test, California Bearing Ratio, pH and permeability test were also performed in order to determine the engineering, behavioral and hydraulic properties of the soil. The results of the geologic and magnetic survey indicated that the study area is underlain by mainly igneous and metamorphic rocks such as gneiss, quartzite, pegmatite, gneiss and calcrete. The results of the soil profiling and the resistivity survey showed that the study area is comprised of sandy soil with either two or three horizons while the cone penetration results revealed high variable soil consistency and stiffness which ranged from very loose to very stiff soils. The particle size distribution, atterberg limits and grading modulus indicated that the study area is characterized mainly by dry, cohesionless and non-plastic to slightly plastic coarse-grained sandy soil with sand content ranging from 71- 96%. From the CBR results, it was found that the soils in the study area generally classifies as G6 material and can be used as base, sub base and backfilling material in accordance with the TRH 14 specifications. The permeability test results indicated moderately permeable sandy silt soils with coefficient of permeability ranging between 1x10-3 to 8x10-3 cm/sec and ground water was encountered at 1.3 m depth. The material excavatability indicated variable material on site ranging from soft calcretes with soft excavation to highly competent material such as quartz and dorbank which require hard excavation while the side wall stability of trial pits indicated stable pit walls during the investigation giving an indication of stability of long pit excavations. The foundation analysis showed that driven piles and earth screws are the ideal foundation types for this site and that the site is generally suitable for construction of the solar facility provided all the recommendations are implemented. / NRF

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