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PhD (Business Administration), North-West University, Potchefstroom Campus, 2019 Small and Medium Enterprises (SMEs) are increasingly becoming the productive drivers of economic growth and development in South Africa. This is so because SME sector is the engine of employment creation and the key contributor to the GDP of the country. Despite their contribution to the development of the economy, the rate of failure and discontinuity of SMEs in South Africa is still one of the highest in the world. A lot of business scholars have addressed the issue plaguing the sector by identifying the causes of SME failure but have not provided a solution on what needs to be done for these business ventures to become sustainable. The purpose of this study therefore was to develop a framework for enhancing the sustainability of SMEs in municipalities of the North West province of South Africa. A number of objectives were set to accomplish the purpose of the study that built up to the development of the proposed framework to enhance the sustainability of SMEs in this region. In order to attain the objectives of this study, the study used five principal theories that address the sustainability of SMEs: the financial gap theory, the resource dependence theory, the theory of mergers and acquisitions, investment theory and trickle-down theory. The pragmatist research paradigm underpinned supported the adoption of a sequential explanatory mixed method approach for collecting and analysing quantitative data in a first phase, while the qualitative phase was built on the outcomes of the preliminary quantitative results. The target population of this study was drawn from the current number of formal (duly registered) SMEs in the North-West province as indicated by the Central Supply Database of the Provincial Department of Finance. This population was chosen from the four district municipalities of the North-West province of South Africa and a non-probability sampling method was used to select a sample size of 400 small business owners and managers for the quantitative phase and 20 for the qualitative phase. The Statistical Package for Social Science was used to analyse quantitative data and Atlas-Ti software was used to analyse qualitative data. The findings of the study indicate that the major causes of SME failure and discontinuity in the North West province is due to various factors such as lack of strategic business planning, lack of sufficient finance, poor management, lack of innovation, lack of business research and low level of human capital education and training. Therefore, it is imperative for SME owners and managers to formulate and pursue a strategic business plan for their businesses, seek for measures to foster an improved flow of finances and implement strategic management in their businesses. More so, it is necessary for SME owners and managers to be innovative in business, conduct business research and upgrade the level of education and training of their human capital to ensure successful and sustainable business enterprises. More importantly, because of their contribution to economic growth of the country, the government should endeavour to support and encourage this sector to develop by offering financial and technical assistance to small business enterprises through relevant departments and agencies. Doctoral

We model the retail market with dynamic pricing as a Stackelberg game where both retailers (leaders) and flexible consumers (followers) solve an economic cost-minimization problem. The electricity retailer optimizes an economic objective over a daily horizon by setting an hourly price-sequence, which is then communicated to the end-consumers. In turn, on the basis of such price sequence, consumers optimize a utility function that accounts both for energy procurement costs and for the benefit loss resulting from deferring consumption. The game is formulated as a Mathematical Problem with Equilibrium Constraints (MPEC) and cast as a Mixed Integer Linear Program (MILP), which can be solved using off-the-shelf optimization software. In an illustrative example, we consider a retailer associated with both flexible demand and wind power production. Such an example shows the efficiency of dynamic pricing as a way to control the load for minimizing the imbalances due to wind power, assesses the overall economic results for the retailer and the consumers as well as the dynamic properties of consumer flexibility.

This report presents an analysis of sensors data leading to an initial assessment of the power performance from sea trails of the DEXA D05 Wave Energy Converter (WEC). The sea trails where performed approx. 1 nautical mile offshore from Hanstholm, Denmark during 2011. The converter was 1:5 scale model of the planned full scale DEXA WEC with a hydraulic Power Take Off (PTO). The converter had sensors to measure mooring forces, motions, as well as pressure and displacement sensors in the PTOs. The report gives the calculated power production efficiency and an analysis of the mooring forces. The DEXA D05 WEC was built, deployed and operated by the client DEXAWAVE ApS and the analysis of the sensor data, given here, has been carried out by John Lavelle under supervision by Jens Peter Kofoed in the Wave Energy Research Group at the department of Civil Engineering, Aalborg University (AAU).

The integration of Variable Renewable Energy Sources (VRES) creates challenges for meeting load demand. The lack of on-demand power generation of these VRES effectively threatens energy security. Therefore, storage facilities, especially hydrogen, have been broadly researched for potential implementation in our energy system, enabling on-demand power "generation". This thesis adds to this research by providing a framework on how VRES and long-term storage technologies can be most optimally utilized to ensure weekly or monthly energy security. This framework is explicitly applied to the Netherlands and reviews the opportunities of a VRES dominated future energy system. The framework consists of a VRES generation model and load model and identifies the optimal load coverage using single- and multi-objective genetic algorithms. The VRES generation model is designed for a weekly and monthly timeframe by using 31 years of available weather data (1988-2018), specifically average wind speeds and solar irradiance, for a number of locations in the Netherlands. Using the available weather data, power generation per MW of onshore wind, offshore wind, and solar PV are calculated. Subsequently, this calculated VRES power generation is compared to available real-world VRES power generation data and a correction factor is determined. Applying the correction factor to the more extensive weather data set allows to effectively create a VRES power generation model, based on the weather circumstances as in these 31 years. Additionally, a weekly and monthly 31-year load profile is determined, using available data for load demand in the Netherlands. Thereafter, both a single and multi-objective algorithm is tasked to provide load coverage in two main scenarios at minimum cost. First, load coverage is achieved exclusively utilizing VRES capacity. Secondly, a variety of long-term storage facilities are introduced in combination with VRES capacity to acquire energy security. Furthermore, these two methods for achieving energy security ...

Thesis (MEng)--Stellenbosch University, 2018. ; ENGLISH ABSTRACT: The development of a prototype variable valve duration reciprocating steam expander was undertaken. A variable valve duration system was developed which could vary the cut-off ratio from 15 % to 90 %. An existing internal combustion engine was converted into the prototype reciprocating steam engine. Thermodynamic models were developed to determine the theoretical power output and working fluid consumption of the manufactured prototype engine. Proof of concept tests were performed on the engine. The engine was operated at 500 rpm where the output power and air consumption were measured. Tests were performed for various cut-off ratios to determine the influence on output power and air consumption. The experimental results showed a strong correlation to the theoretical effect of cut-off ratio on power output and air consumption. The maximum experimental output achieved was 1.396 kW at an 80 % cut-off ratio. The experimental power output was lower than the theoretical results which neglected mechanical losses in the system. The thermodynamic model over predicted the air consumption due to the assumption of instantaneous valve events. ; AFRIKAANSE OPSOMMING: Die ontwikkeling van 'n prototipe veranderlike klep duur wederkerige stoom uitsitter is onderneem. 'n Veranderlike klep-duurstelsel is ontwikkel wat die afsnyverhouding van 15% tot 90% kan wissel. 'n Bestaande verbrandingsmotor was omskep as die bewys van konsep wederkerige stoom-enjin. Termodinamiese modelle was ontwikkel om die teoretiese kraguitset en werkvloeistofverbruik van die vervaardigde prototipe-enjin te bepaal. Bewys van konseptoetse is op die enjin uitgevoer. Die enjin is teen 500 rpm bedryf en die uitlaatkrag en lugverbruik was gemeet. Toetse is uitgevoer vir verskillende afsnyverhoudings om die invloed op die uitsetkrag en lugverbruik te bepaal. Die eksperimentele resultate het 'n sterk verband getoon met die teoretiese effek van afsnyverhouding op kraguitset en lugverbruik. Die ...

Spider webs must be able to absorb the energy of impacting insects, and similarly, rock support must absorb the energy of ejected rock in rockbursts. A consideration of the properties of spider webs shows that spider silks (threads) are extremely strong, typically three times as strong as common steel. Spiders also construct their webs with yielding mechanisms to enhance their energy-absorbing capability. In this paper, the techniques employed in web construction are compared with those used in rock support in excavations prone to rockbursting. It is shown that the design of rockburst support could benefit from some of the capabilities used by spiders in the construction of their webs.

Metadata only record Within the last thirty years in the West African Sahel, farmers have started to implement agroenvironmental practices which have allowed them to improve the soil quality and increase crop yields. Using two examples of land rehabilitation in Africa, this paper examines the technical and institutional innovations and their impacts on the ability to meet food demand for the growing population. Agroenvironmental techniques incorporate trees into the agricultural landscape, which improves water retention in the soil, increases the supply of nutrients, reduces wind erosion, and provides other marketable tree products. This large-scale effort has created income opportunities for farmers, benefited women, and increased food supply for many African families.