Cape Peninsula University of Technology
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Voltage stability assessment and wide area protection/control using synchrophasor measurements
No full textThesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.Electric power systems are being operated closer to their designed stability limits due to the constraints caused by the continuous increase in system loading, and the lack of new power stations and transmission network infrastructure to support this increase in system loading. This coupled with the practice of long distance bulk power transmission and cascading contingencies, makes system instability and consequently blackouts inevitable. In such scenarios, system instabilities like voltage instability becomes a serious threat to the secure operation of the power system, and voltage collapse (system-wide blackouts) are prone to occur. This is often compounded by the unavailability of real-time system measurements for situational awareness from the existing Supervisory Control and Data Acquisition (SCADA)/Energy Management System (EMS) platforms which are usually based on unsynchronized SCADA measurements with a slow reporting rate of 1 measurement every 2-10 seconds. This Doctoral thesis proposes non-iterative algorithms and methods of solution based on the IEEE C37.118 synchrophasor measurements from Phasor Measurement Units (PMUs) with a high reporting rate of up to 200 measurements every second (200 fps) for voltage stability assessment and automated wide area Centralised Protection/Control (CPC) against catastrophic voltage instabilities/blackouts in power systems. Extended formulations are proposed for the Optimal Placement of PMUs (OPP) in power systems with respect to voltage stability assessment. The impact of zero injection buses, critical buses, and PMU redundancy is considered in the formulation of the OPP problem solution. The extended formulations made use of Binary Integer programming (BIP) and Modal Participation Factors (MPFs) derived from the eigenvalues of the power flow Jacobian
Integrated solar photovoltaic and thermal system for enhanced energy efficiency
No full textThesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.South Africa has raised concerns regarding the development of renewable energy sources such as wind, hydro and solar energy. Integration of a combined photovoltaic and thermal system was considered to transform simultaneous energy into electricity and heat.
This was done to challenge the low energy efficiency observed when the two solar energy conversion technologies are employed separately, in order to gain higher overall energy efficiency and ensure better utilization of the solar energy. Therefore, the notion of using a combined photovoltaic and thermal system was to optimize and to improve the overall PV panel efficiency by adding conversion to thermal energy for residential and commercial needs of hot water or space heating or space cooling using appropriate technology. The PV/T model constructed using water as fluid like the one used for the experimental work, presented a marginal increase in electrical efficiency but a considerable yield on the overall PV/T efficiency, because of the simultaneous operation by coupling a PV module with a thermal collectors
Graphic design students’ perceptions of work practice
No full textThesis (MTech (Graphic Design))--Cape Peninsula University of Technology, 2016.The aim of this study was to examine how students experience the transition
from the classroom to the workplace. This research explored what factors
students found problematic and which factors was helpful during the transition.
This research was qualitative and this study focused on the experiences of the
participants and all data was collected from their perception of work practice. I
used Activity Theory as a theoretical framework to compile and organize
relevant data. Data was gathered using video recordings, hand written journal entries and
individual interviews. The research was conducted in an on-campus design
studio that is situated within the Design Faculty at Cape Peninsula University of
Technology. The reason for choosing Design Logic as a site is the following;
the studio sits neatly between the classroom and the workplace, although the
studio is in a protected environment, most of the elements that are present in a
real world setup is reflected within Design Logic i.e. the stresses of satisfying
demanding clients, working with budgets, liaising with suppliers and the ever
present looming deadlines all form part of the daily make-up of Design Logic. Although the starting point of the study was to search for the problem areas
of the student’s transition into the work place, the analyzed data revealed the
dissimilarities between the two systems and how the participants overcame
the difference i.e. shifting identities and rules and norms to develop new skills
suited for the work place. The workspace opened a Zone of Proximal
Development (ZPD) and highlighted the value and importance of work practice
in preparation of graduates for industry
The co-design of a visual arts-based intervention within the community of the Olifants River valley in South Africa
No full textThesis (MTech (Design)--Cape Peninsula University of Technology, 2016.The research was motivated by my lived experience in the Olifants River community of Namaqualand. In this community there are many diverse ethnic and social groupings with considerable potential to contribute to indigenous knowledge and creative practices. These groupings are, however, fragmented, with no platform for their varied and rich cultural assets to be displayed and acknowledged. In addition, the research was motivated by the call for a platform for the arts in the region. It is argued that visual art practice is an instrumental tool in the advancement of both creativity and social cohesion in this community. The research commenced with a pilot study, comprising workshops, which were run by art practitioners from various sectors in the region. Primary literature that influenced the emerging research design was that of Solomon (2007) as well as the holistic cultural viewpoints of Schafer (2014). The organic process of qualitative research methods as described by Ellingson (2009) was a natural personal directive. Body mapping was used during a preparatory phase that led to the creative exploration of community members’ own identity. Storytelling and dance were included in the design methodology since they enabled a psychosocial process of validating art practice as an economic asset within the community as well as enhancing social cohesion in the community. Crystallisation methods implemented in the process-driven body map workshops were held for grassroots -, town – and township sectors in the Olifants River valley. Each of the workshops comprised ten participants who were invited to participate in a subsequent do-designed collaborative event
Design of a high efficiency S-band power amplifier for a Cubesat
No full textThesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.In all radio frequency (RF) electronic communication systems, power amplifiers (PAs) are used to generate the final transmitted signal. Specifically, these PAs are used to increase the output power of the transmitted signal. The PA accomplishes this by converting the applied direct current (DC) power to the PA into RF power, while being driven by a RF input signal. The portion of DC power that is not converted into RF power is dissipated as heat. The power conversion mechanism that takes place in a PA is described by the power conversion efficiency (PE) and the power added efficiency (PAE).
A CubeSat is a small satellite in the shape of a 10 × 10 × 10 cm cube, weighing less than 1 kg and contains a RF electronic communication system which allows communication with the satellite. A CubeSat requires a PA with high PE in order to increase the lifetime of the on-board battery, facilitate thermal management on-board the satellite, increase system reliability, and reduce the size and manufacturing cost of the satellite. To maximize the theoretical PE of a RF PA, several design techniques and classes of operation were investigated, the basis of which lies in the fulfilment of the necessary and sufficient conditions for a maximum PE. A PA, which uses the Class-F-1 (inverse Class-F) mode of operation, fulfils the necessary and sufficient conditions for a maximum theoretical PE, and therefore presents itself as a good option for a high efficiency PA.
This thesis presents the design of a Class-F-1 PA, using the Cree CGH40010F GaN power active device. An optimum output matching network is used to terminate the drain of the GaN power active device with the required load impedances at the fundamental, 2nd and 3rd harmonic frequencies of operation. The designed PA delivers a maximum PE of 95 % at an operating frequency of 2.2 GHz, a maximum PAE of 82 % at an operating frequency of 2.2 GHz and a maximum output power of 40.6 dBm at an operating frequency of 2.2 GHz
Bingham yield stress and Bingham plastic viscosity of homogeneous Non-Newtonian slurries
No full textThesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.This dissertation presents how material properties (solids densities, particle size distributions, particle shapes and concentration) of gold tailings slurries are related to their rheological parameters, which are yield stress and viscosity. In this particular case Bingham yield stresses and Bingham plastic viscosities. Predictive models were developed from analysing data in a slurry database to predict the Bingham yield stresses and Bingham plastic viscosities from their material properties. The overall goal of this study was to develop a validated set of mathematical models to predict Bingham yield stresses and Bingham plastic viscosities from their material properties.
The interaction of the non-Newtonian material properties is very complex at varying mass solids concentrations. The evaluation of these interactions in terms of constitutive equations is almost impossible and the relationship between material properties, mass solids concentration and rheology can only be modelled in a statistical manner. The validity of each model is checked to ensure that predictions and interpretations are unbiased and efficient. This is done by comparing the resulting models to experimental data generated from test work. An in-depth analysis was conducted to see the interrelationship between the material properties and how they affect the yield stress and viscosity values
The “suitcase hypothesis” – can eddies provide a pathway for gene flow between Madagascar and KwaZulu-Natal?
No full textThesis (MTech (Oceanography))--Cape Peninsula University of Technology, 2016.Similarities in marine fauna found off the coasts of southern Madagascar and KwaZulu-Natal (KZN, South Africa) led to the development of the “Suitcase Project”, with the aim of establishing whether eddies that form off southern Madagascar may package and transport biological material, as if in a suitcase, across the Mozambique Channel. In pursuit of this question, sampling was conducted on the southern Madagascan shelf and along a transect across a cyclonic eddy which originated off the southern tip of Madagascar, between the 15th and 23rd of July 2013. Bongo nets (300 and 500 μm-mesh) and a neuston net (900 μm-mesh) were used to collect zooplankton within the upper 200 m and at the surface, respectively. Samples were sorted for meroplankton (larval stages of fish and benthic invertebrates) under a stereo microscope, particularly seeking species known to be common to both the east coasts of Madagascar and South Africa and, thus potential indicators of connectivity between these regions. Larvae of crabs, rock lobster, and fish were used for DNA barcoding. Zooplankton biovolume and abundance were compared between the eddy core, eddy periphery and outer regions of the eddy, as well as stations from the Madagascan shelf. Mean neuston biovolume on the Madagascan (0.08 mL m-3) was not significantly higher than that in the eddy (0.06 mL m-3). Mean bongo biovolume in the upper 200 m was much higher on the Madagascan shelf (0.62 mL m-3) than in the eddy (0.16 mL m-3) although only 2 stations were sampled on the shelf. Highest biovolume in the eddy was recorded in the west eddy zone (0.25 mL m-3) and west outer zone (0.23 mL m-3), which was not statistically significantly higher than the eddy core (0.12 mL m-3) and east eddy zone (0.17 mL m-3). Meroplankton was comprised of coastal origin taxa and was most abundant on the shelf and in the eddy perimeters. Larval goat-fish, Parupeneus fraserorum was identified, a newly described mullid, and has been recorded on both the coasts of Madagascar and KZN, SA. Larvae of coastal invertebrate species identified, include the squat lobster Allogalathea elegans and camel shrimp Rhynchocinetes durbanensis. Other larval fish identified, but not found in high abundance include the families of reef associated fishes, for example: Apogonidae, Labridae, Pomacentridae, Priacanthidae, Serranidae and Sparidae. Higher zooplankton biovolumes, larval abundances and reef-associated larval assemblages found on the Madagascan shelf and in the periphery of the cyclonic eddy compared to the core in this study provide support for the suitcase hypothesis that planktonic organisms are entrained within eddies as they propagate south-westwards of the Madagascan shelf. However, further studies are required to determine whether planktonic larvae are able to cross the Mozambique Channel and reach the KZN coast in time to settle
Effect of Rooibos preparation on the total polyphenol content and antioxidant capacity of herbal tea and its consumer characteristics
No full textThesis (MTech (Consumer Science: Food and Nutrition))--Cape Peninsula University of Technology, 2016.Background: The different types and forms of rooibos and the ways in which it is prepared and
flavoured for consumption influences its total polyphenol content and total antioxidant capacity
(TAC) and hence depends on its consumer practices.
Design: Phase 1 of the study entailed the selection and preparation of different rooibos types
and forms; rooibos brewed for different times; and with different household and commercially
added flavourings to determine the total polyphenol content, TAC, flavonol and flavanol content;
and subsequent identification of the optimal cup of rooibos based on the first two biochemical
parameters. For Phase 2 a questionnaire was used to obtain information on the profile of the
adult rooibos herbal tea consumer, as well as of those consuming the optimal cup of rooibos.
Results: The following prepared rooibos samples delivered the higher biochemical parameter
content: green / unfermented (type representative); green / unfermented leaves and powdered
extract (form representatives); that brewed for 10 minutes or longer; and those with added
honey. The optimal cup of rooibos was identified as the one brewed for 10 minutes or longer.
The older respondents and those with a lower level of education consumed a higher daily
amount of rooibos (p < 0.05) and those who brewed rooibos in a teapot consumed the optimal
cup (p < 0.05). However, very few respondents consumed the advised number of cups per day
(< 1%) and the identified optimal cup (15.9%).
Conclusions: Rooibos consumers in this study did not consume it in sufficient amounts and did
not brew it for long enough to fully gain from its attributed health benefits
A framework for software patch management in a multi-vendor environment
No full textThesis (MTech (Information Technology))--Cape Peninsula University of Technology, 2016.Software often requires patches to be installed post-implementation for a variety of reasons. Organisations and individuals, however, do not always promptly install these patches as and when they are released. This study investigated the reasons for the delay or hesitation, identified the challenges, and proposed a model that could assist organisations in overcoming the identified challenges. The research investigated the extent to which the integration of software patch management and enterprise data security is an important management responsibility, by reviewing relevant documents and interviewing key role players currently involved in the patch management process. The current challenges and complexities involved in patch management at an enterprise level could place organisations at risk by compromising their enterprise-data security.
This research primarily sought to identify the challenges causing the management of software patches to be complex, and further attempted to establish how organisations currently implement patch management. The aim of the study was to explore the complexities of software patch management in order to enhance enterprise data security within organisations. A single case study was used, and data were obtained from primary sources and literature. The study considered both technological and human factors, and found that both factors play an equally important role with regard to the successful implementation of a patch management program within an organisation
Plastic waste gasification using a small scale IR reactor : experimental and modelling analysis
No full textThesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.The generation of municipal solid waste has increased significantly due to the exponential population growth and it has become a global issue. Gasification technology, an alternative method for waste treatment is a thermochemical process where carbon-based material are exposed to an environment deprived in oxygen, was used for this project.
The aim of this thesis is to study the gasification of plastic waste which is a potential alternative energy source using infrared heaters. To achieve this goal, fundamental studies have been numerically and experimentally conducted for an infrared gasifier and subsequently establishing the temperature profile for gasification using a small scale reactor.
A detailed study on low density polyethylene was conducted using Infrared Spectrometry and thermal decomposition techniques such as Thermogravimetry and Differential Scanning Calorimetry were performed to establish the temperature at which plastic pellets sample used for this research gasify. The gasification behaviour of pelletized low density polyethylene (plastic pellets) was tested and three case studies were done to evaluate the most suitable temperature profile for the reactor to gasify the low density polyethylene at high temperature for less amount of time. Subsequently, the reactor model was simulated and results validate the use of reactor at an optimum temperature of 800 °C for a gasification process with less residue content.
The reactor designed for this research is fully functional and validates the temperature behaviour predicted during simulation. The experimental results show infrared heaters are suitable for gas production using this gasification process