Theses and dissertations (Engineering and Built Environment)
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Item Crash modeling of a light composite aircraft(2014) Moletsane, Moeletsi Augustinus; Jonson, DavidABSTRACT The study presented here was focused on the crash analysis of light composite aircraft on relatively survivable accidents. The crash analysis approach was based on the numerical simulation using the finite element software (MSC.Dytran). The aircraft crash environment, impact terrain, impact angles and material properties were identified, and later introduced into the aircraft crash model. The background on composite materials is discussed and more focus was given to their response at high strain rates. The modeling methodology is also discussed with more emphasis on the finite element analysis approach and the failure theories behind composite materials. The failure criteria are based on assumptions considered for the classical lamination theory, and each of the failure theories in MSC.Dytran were evaluated before being introduced into the crash model. The Tsai-Wu failure criterion was found to be capable of predicting the progressive ply failure of the composite lamina. The Ravin 500 light composite aircraft model was used for the purpose of this study and four crash scenarios of impacting the aircraft onto the soil model were considered. The aircraft was impacted at the same crash velocity but different flight path angles were considered. The 10⁰, 15⁰, 20⁰ and 30⁰ crash angles together with a crash velocity of 22m/s were used. The impact approach was influenced by the previous literature; it shows that the structural damage of an aircraft during crash accident is affected largely by the crash angle. The results of each crash scenario are presented and mainly focused on the failure response of the aircraft structure. The conclusion on the crashworthiness of the Ravin 500 light composite aircraft is also drawn based on the numerical work. Details regarding the future work or recommendations for the design philosophy and means of improving the crashworthiness of the light composite aircraft are also presented. In addition, more emphasis is focused in the occupant’s space within the aircraft.Item Resolution of management issues with mega projects(2019-05-25) Mhlongo, Scelo; Aiyetan, Olatunji AyodejiSouth Africa is a developing country with many construction projects that are being undetaken. The study aims to contribute to the resolution of issues around the management of projects. Previous studies have revealed that there are many failures in the erection of mega projects. This study was based in three provinces in South Africa - KwaZulu-Natal, Gauteng and Western Cape. A mixed method research approach incorporating both qualitative and quantitive methods was used to collect empirical data from stakeholders working on mega projects. The data was collected using a structured questionnaire and focused individual interviews. The study established that management issues such as the lack of stakeholder engagement and poor logistics planning play a role in the failure of mega projects. The level of use of this research targeted companies which are at 8GB and 9GB and within those companies, professionals such as project managers, architects, quantity surveyors, foremen and site agents. The study recommends that in order for mega projects to be successful, stake holders must mitigate turnaround time on taking decisions. Also, sound decisions must be taken for effective delivery of mega projects. Findings suggests that plant down time contributes to the failure of a project. Regular plant schedule checking is done daily prior to plant operation. Findings on logistic management revealed that the leading factor is public safety. It is recommended that safety of public around projects needs to be managed closely by responsible site agents and safety officers. The change of designs during construction must be avoided since this brings unexpected material expenditure which impacts on the project costing. All cost occurring during design changes must be charged to the architect fees, unless the changes were unforeseen.Item A study of biogas generation from poultry litter and its impurity removal(2019-01) Osagie, Ighodaro; Lazarus, I. J.; Reddy, G.K.; Singh, RamkishoreThis study is focused on the anaerobic digestion of poultry waste to produce biogas. Waste was collected from three different poultry farms (Sekela farm, Emarldene and Parkside poultry industry) in Kwazulu-Natal, South Africa. The aim is to assess energy from poultry waste in Kwazulu-Natal and to enhance the process of biogas production by treating the impurities of sulphur content, moisture and carbon dioxide in the biogas. The objectives are: to determine the energy potential of poultry waste in Kwazulu-Natal region, to increase the energy density of the biogas by the removal of moisture content, incombustible and corrosive gas and to assess techno-economic feasibility of biogas generation from poultry waste. 1 kg of each waste was thoroughly mixed with 3 L of water and loaded into ten digesters with each water bath (thermal conductor) bearing two digesters. The slurry was investigated using water displacement method to determine biogas produced for a period of 21 days and at an average temperature of 30 0C, 31 0C, and 32 0C respectively. Production started on the 3rd day for each digester at different temperatures (30 0C, 31 0C, and 32 0C), and attained maximum value on the 14th and 15th days. The maximum amount of biogas produced was 265.6 ml at a temperature of 32 0C from waste A (Sekela farm). At 32 0C, an optimal biogas yield of 421.6 ml/g VS was observed from Sekela farm (poultry waste A) compared to Emarldene (370.10 ml/g) and Parkside poultry industry (349.10 ml/g) in KwaZulu-Natal. Biogas was collected from the digester with the maximum volume of biogas produced using 100 µʟ gas syringe and was taking to Gas chromatography for characterization. The result showed that it was composed of about 57.71 % methane (CH4), 26.8 % carbon dioxide (CO2), 0.8 % nitrogen (N2), traces of hydrogen sulfide (H2S), fractions of water vapor, and other impurities which the detector was unable to quantify with an energy potential of 0.028 MJ/ml. Purification and Upgrade system was comprised of one column charged with steel wool (iron sponge), and two cylinders charged with pressurized water and silica gel to treat H2S, CO2, and water vapor in the biogas for improvement of its energy density. Biogas was collected from the purified system using gas syringe to the Gas chromatography for characterization and result showed that it is composed of about 84.56 % CH4 and energy potential of 0.046 MJ/ml. The result confirmed that the biogas heating value/energy density was improved/increased using steel wool, pressurized water and silica gel as biogas contaminants removal. Techno-economic studies were carried out to assess the techno-economic feasibility of a small-scale biogas plant using poultry waste in KwaZulu-Natal. A fixed dome digester was selected as the most convenient technology for the community. Result showed that 2,160 kWh per year of energy could be produced from about 4,000 kg of poultry waste and the payback time was eleven years and nine months. It showed that it is techno-economically feasible to use a fixed dome digester for energy generation for domestic usage and is cost-effective. In conclusion, poultry waste as a feedstock is suitable for anaerobic digestion, producing methane which can be used as an energy source and which can be purified to improve its energy potential. Biogas optimization is dependable on: temperature, physio-chemical characteristics of waste, pH and retention time e.g. at same temperature (either 30 0C, 31 0C or 32 0C) and time, waste A production is higher than waste B and C because of its favorable physio-chemical characteristics and pH-value. It is deduced that the energy potential in poultry waste could be determine by treating the waste via anaerobic digestion and the increase in the energy density of the waste is dependable on temperature, pH, retention time and physio-chemical characteristics of the waste.Item Comparative analysis, design and optimisation of a 48 channel DWDM system using various design parameters(2019) Mohan, Jerrin Zachariah; Sokoya, Ayodeji SokoyaIn the current era, there is an ever-growing demand for data hungry applications and services that need large amounts of bandwidth to send digital information at very high speeds. In order to meet this challenge for higher bandwidth capacity, Dense Wave Division Multiplexing (DWDM) is used as the strategy to transmit multiple high-bit rate channels at extremely narrow channel spacings over a single fiber core. However, this gives rise to detrimental transmission impairments such as linear effects and non-linear effects. The dissertation minimises the impairments by optimally designing a new DWDM system that produces a detectable and acceptable quality of signal at the receiver. In this dissertation, a comparative analysis is performed on the simulative design of a 48-channel DWDM system that has a 25 Gb/s bit rate and a 100 km transmission distance. The research mitigates the effects of transmission impairments such that an error-free matched communication link is produced for equally spaced (ES) channels of 100 GHz, 50 GHz, 25 GHZ and 12.5 GHz and 6.25 GHz. Various design parameters are used to create the comparative analysis model to optimise the 48 channel DWDM network. The design is simulated using the Optisystem simulation platform and the signal analysis is based on the bit error rate (BER) and quality (Q) factor of the received signal’s eye diagrams. It is established in the desertion that modified networks with matched active components has ES frequency channels that are aligned to each other and has a higher optical signal to noise ratio (OSNR) than mismatched networks. The maximum signal power and OSNR of the 3-erbium doped fiber amplifier (EDFA)-post symmetric compensation technique is always higher than the 1-EDFA post compensation technique for all channel spacings in any type of network. Modified duobinary return to zero (MDRZ) when compared to non-return to zero (NRZ) and return to zero (RZ) has a greater dispersion tolerance, higher fiber non-linearity tolerance and a higher acceptable signal transmission over longer distances with the least amount of errors. The optimised design parameter configurations produce the highest signal performance (highest Q factor > 6 and lowest BER > 10-9) and the highest bandwidth efficiency for the RZ Modulation (at 100 GHz, 50 GHz and 25 GHz channel spacings) and MDRZ Modulation (at 12.5 and 6.25 GHz channel spacing).Item Technical analysis mitigation of electricity theft for domestic and commercial end users(2019-08) Jiyane-Tshikomba, Salome; Davidson, Innocent Ewaen; Ojo, Evans EshiemogieUtility services are experiencing common problem of power losses, which impose a big impact on their annual budget. Practically, power losses consist of technical losses and non-technical losses. Technical losses are due to operations and ageing of infrastructure, while non-technical losses (NTL) are due to non-metered energy. The focus is on managing non-technical losses using an automation wireless method. The wireless ZigBee technique is proposed and further investigated for communication failure over long distances, while solving the problem of stealing of electricity. Advance-metering infrastructure (AMI) technique and smart meters are feasible for system integration that is why they are chosen to be part of this study. The success of the study depends on quality data of the Utility, meaning the more accurate the data, the easier the analysis of outliers. The operation and planning of revenue protection contains large amount of data that needs to be worked on, so data mining assist in that regard. Then the load profiling method assist in illustrating the variation in demand/electrical load over a specific time. The wireless communication technique will be used as a viable solution in curbing electricity theft. The uniqueness of the proposed ZigBee system is that it recognizes the common act of stealing electricity through tempering with the meter box and tapping of the supply. The survey and the pilot project was utilized to achieve the goal of the study. The survey conducted is in tandem with the objective of the thesis. The research questions that were developed and tested provided a proven percentage score of positive responses to the questionnaire. Though some respondents were dodgy because they were still happy with the fact that they were still indulging in theft of electricity, therefore, they saw the thesis as an avenue to rob them of freedom to continue the pilferage of electricity without any legal penalties imposed on them. The cost associated with energy losses that are caused by illegal electricity connections will decrease by upgrading the infrastructure, installing the ZigBee technique, and by giving attention to the communication system and its problems. The wellness and workshops need to be conducted so that communities at least once a month will learn the basics of the danger associated with connecting electricity illegally. The pilot project also showed good results, whereby the cost of 3000 units (meters) piloted expense was R8.5Million but the return on investment was R24Million.The proposed ZigBee technique is feasible, and will improve revenue of the Utilities.Item An investigation into the structural suitability of standard grade Expanded Polystyrene (EPS) as an innovative building material(2019-11) Mncwango, Bonke; Allopi, DhirenRapid urbanization has brought numerous economic, cultural and political development in South Africa; however, it has also led to some parts of the country turning into slums. The spread of slums is mainly driven by the lack of adequate housing provision by the Government. Although it has been twenty-five years since South Africa had its first democratic elections, millions of citizens still continue to live under squalid conditions as a result of lack of housing. The South African government cites numerous reasons for not being able to eradicate the housing backlog, including insufficient housing budget allocation as well as the worsening global economic climate. It is evident from the current housing backlogs that more building solutions that can reduce cost and construction time are needed. Further, new building materials should be explored in order to alleviate the environmental pressures that conventional building materials cause on the environment. This research investigates the properties of standard grade Expanded Polystyrene (EPS) as a potential contributor in low-cost housing provision. Currently the construction of EPS dome houses using modified EPS is only occurring outside of South Africa and it requires the possession of intricate moulding equipment. Existing suppliers require a minimum order, for instance, Japan Dome House Company supplies dome houses at a minimum order of three-hundred units. This research examines the potential of carving standard grade EPS into a form of dwelling using a hot-wire tool to re-create a model similar to a commercially produced EPS dome house. EPS components were assembled and left exposed to the elements since the main method of analyses of the live model was through exposure, particularly against rain and wind experienced within the jurisdiction of Pietermaritzburg, South Africa. Analyses of the live model was supplemented by testing of compression, flexural and thermal qualities of EPS under laboratory conditions. With wind speeds of thirty-nine km/hr and a rainfall intensity of twenty-eight mm, the model was found to still be in its original state of composure after six-months even without having been permanently anchored to the ground. Existing industry models such as Moladi, Khaya ReadyKit and Fischer Housing were examined to provide a standard of comparison for this investigation. This was done in order to distinguish how EPS dome houses differ to current existing alternative building technologies within the sector of low-cost housing. Observation of the model revealed that it is possible to successfully re-create an EPS dome house without complex moulding equipment. Some of the main findings from the laboratory analysis were that, contrary to expectations, thermo-gravimetric analyses of three different densities (fifteen kg/m3, twenty kg/m3 and thirty kg/m3) revealed that as the density of EPS increases, the maximum degradation value decreases. A study of the interaction of the polystyrene beads through microscopic analysis revealed that in higher EPS densities beads can rupture, leading to a compromise in both structural integrity and form. A water absorption test on EPS revealed that the percentage of water absorbed by EPS is similar to that absorbed by clay bricks over a 24-hour period, which makes the materials comparable in this regard. In terms of the outcomes of the study, the researcher has already published articles in three journals and two conference proceedings. This research will be of value to design professionals in alleviating the environmental impacts of commonly used conventional materials through the inclusion of EPS where low compressive loads are permissible.Item Viability of supercapacitors for energy storage to mitigate renewable energy sources intermittency(2019-10) Thakoordeen, Renesh Rajan; Ojo, Evans EshiemogieEnergy storage is seen as a solution to assist in the integration of renewable energy by meeting intermittency. Such energy sources suffer from the widely known obstacle of intermittency. To overcome this issue, a formidable energy storage system is required. While large scale energy storage systems such as pumped-storage schemes and compressed air energy storage systems exist, renewable energy sources such as solar and wind power use batteries as a form of energy storage. Additionally, these large scale energy storage systems suffer from a number of drawbacks such as specific location and geophysical requirements. Photovoltaic arrays and wind turbines almost exclusively use batteries as the preferred method of energy storage. Recent years has seen a surge in the advancement of supercapacitor technology. The two main characteristics of supercapacitors are: high power density and low charging time. This has drawn considerable attention to the technology and has thus been implemented in electric buses and hand tools. Other desirable characteristics, as compared to electrochemical batteries, include: smaller weight; lifespan and fewer toxic materials. The last characteristic mentioned is of notable concern since lead-acid batteries are known to emit dangerous gases such as hydrogen and also use sulphuric acid and lead in their production which can lead to laryngeal carcinoma. Latest developments have seen an increase in the overall capacitance (and decrease in cost price) of supercapacitors which may allow supercapacitors to be used as energy storage system, either in a stand-alone or hybrid capacity or both. This study attempts to prove that supercapacitors can replace electrochemical batteries on a domestic scale through simulation where the number of supercapacitors required to supply a domestic load for 24 hours is determined. The time required to charge these supercapacitors is also ascertained. However, it was found that supercapacitor technology is limited to smaller applications or a hybrid design working in conjunction with batteries as protection surge currents.Item A roadmap for improving the manifacture of automotive heat exchangers through value stream mapping(2019-07-05) Lusiba, Kate; Dewa, MendonLean manufacturing is an optimum approach for the reduction and elimination of waste within an organization. The case study company is based in South Africa and produces heat exchangers through main processes or fractals, which include pre-assembly, core building, brazing and final assembly. A walk through the plant showed that there was a large amount of inventory awaiting final assembly and that the brazing furnace often waited for material from core building. This was an indication that there could be an imbalance between the three fractals in terms of cycle time. Thus, the aim of this study was to improve the manufacturing processes for heat exchangers at the automotive manufacturing company through the deployment of value stream mapping, subsequent line balancing and developing a roadmap for reduction of waste. The case study research strategy was adopted for the study since it provided an in-depth view of phenomena. The first objective was to outline the production flow for the manufacture of automotive heat exchanger parts. The method used was a walk through the plant and observations were made to gain an understanding of the production steps from logistics production planning to shipping of the finished goods, and subsequently to a mapping-out of the production process flow was undertaken. The results showed that there was a large amount of inventory awaiting final assembly and that the brazing furnace often waited for material from core building. It was concluded that there was need to conduct a detailed process analysis to identify sources of waste. The second objective was to conduct value stream mapping for assessing the value- and non-value-adding activities in the manufacture of automotive heat exchangers components. A value stream map was developed through walking to Gemba and mapping out the production process, collecting data and pinpointing waste activities or areas to be improved. The kaizen flashes from the value stream map also revealed that operators were not fully utilizing the capacity of the bottleneck workstations. It was concluded that two instead of one planning points, and inefficiency at assembly were root causes of the high work-in-process level. The third objective was to conduct a line balancing analysis for the three production fractals. The method used was a Pareto analysis for evaluating the products, analysing the product mix and line balancing analysis of the production line. The results revealed that the furnace was run on two shifts while the subsequent assembly and preceding core building were running on three shifts causing a work-in-process build-up, thereby resulting in line imbalance. It was concluded that it was imperative to change the scheduling approach, and adopt one that prioritised and spread the cores that had relatively short cycle times, and also reduce downtime, change-over time as well as additional time for scrap and defects, and a future-state balance chart revealed that the fractals imbalance had been reduced. The fourth objective was to develop a roadmap for reduction of waste in the manufacture of car heat exchangers components. The method used was to develop proposals and assess the feasibility and cost implications of implementing each option. Recommendations were made for continuous process improvement and a roadmap for reduction of waste was proposed. In order to improve the output of assembly, training for the operators was recommended since it would also enable the removal of the second planning point at assembly. Further research could also be conducted to develop an optimal scheduling algorithm for allocation of products to work centres to ensure high utilization of work centres and reduce work-in-process inventory.Item The impact of poor power quality and harmonics on the performance of an electrical power network(2019) Nkonyane, Mfanasibili Stanley; Ojo, Eshiemogie; Rigby, BrucePoor power quality has a negative impact on electrical protection systems, rotating machines, transformers, control circuits, electronics, and power electronics equipment. The demand from industries to use power electronics equipment leads to more poor power quality issues – especially relating to harmonics. Determining the level of harmonics in an electrical network has become a necessity, as most electrical equipment are susceptible to harmonics. Previously, electrical networks on the customer side consisted mostly of direct current and induction motors, which resulted in simple networks that were easy to model using various types of simulation software. Today’s electrical network is considered complex due to power electronic equipment such as variable frequency drives (VFDs), uninterruptible power supplies (UPSs), switch mode power supplies (SMPSs) and other electronics equipment. Power electronic equipment are primary source of harmonics and are also susceptible to harmonics. To protect the electrical network infrastructure, it is very important to identify the level of harmonics content in an electrical network, so that solutions can be developed to minimise the harmonic level to acceptable limits – as determined by power quality or harmonics standards. This dissertation presents an analysis of the performance of an island electrical network for an offshore crude-oil drilling ship. A real-time digital simulator was used as a systematic analytical tool to study the level of harmonics in a reduced-scale electrical network model, used to represent the real drilling ship power network. The study objective was to evaluate the behaviour of the power network when direct on line (DOL) starters and variable frequency drives are used to run induction motors coupled with mechanical loads. The waveforms from a limited number of field measurements on the actual network are compared to those obtained from the reduced-scale real-time simulation model of the plant. The study reviews the theory and literature of power quality, generators, transformers, variable frequency drives, and induction machines, and focuses on poor power quality as contributed to by harmonics. The investigation was based on 12 pulse rectifiers for all variable speed drives, which are standard for drilling ships and other offshore installations – as they offer advantages in reducing the fifth and seventh harmonics. Both the field measurements and real-time simulation results in the dissertation indicate the presence of similar harmonic waveforms, and with comparable frequencies – but with different amplitudes. Unfortunately, the simulation results could not be closely matched to the field results, as most operating parameters that are needed for better representation of the plant in the simulation model, could not be obtained within the limited time available for field measurements. Nevertheless, the model developed could be used with a greater degree of accuracy to demonstrate the level of harmonics for an offshore drilling ship power network, provided all operating conditions’ parameters are available.Item Development of a project delivery model for Umgeni Water : infrastructure projects(2019-05-05) Naidoo, Ashok Deenadayalan; Aiyetan, Olatunji AyodejiProject delivery challenges encountered within the built-environment is a global phenomenon. Factors causing project delivery challenges in construction projects differ between countries, due to various fundamental reasons. The fundamental reasons that could exert an influence on project delivery challenges could extend into numerous causes relating to; the client, project planning, risk management, cost estimating, communication, quality and project management approach. The construction industry is a key component to the economy, however many construction infrastructure projects are hindered because of project delivery challenges and fail to be delivered successfully. This study aims at identifying lack of performance and its effects on project delivery for construction infrastructure projects and to develop a project delivery model to mitigate or minimise these challenges for Umgeni Water. A typical Likert Scale using a five-point gauge statistical tool was used for the data analysis. The sample population derives from Umgeni Water employees involved in the planning and implementation of construction infrastructure projects. The sample group consists of qualified and experienced professionals that are project managers, civil engineers, planning engineers, quantity surveyors, servitude administrators and environmental project managers. Findings that were identified as major project delivery challenges at Umgeni Water include the following; • Insufficient planning and designing done during the project, communication problems within the project; • Inadequate attributes and capabilitii;is endorsed by the project manager that hinder the implementation of a good project management approach; • Inadequate participation and contribution by the client during the project; • Project risks that are poorly identified assessed, mitigated and controlled during the project; • Unsatisfactory cost estimating resulting in errors and oversights, and • Oversight of critical quality factors during the project. Recommendations include: (1) the project team must ensure that ample effort is applied at the beginning of the project, sufficient time must be allocated to successfully complete the planning and designing process and consultants must be selected on their experience rather than low bidding; (2) the following courses / modules are recommended for inclusion in built environment tertiary education programmes for all disciplines. They are: design management, quality management, cost management, operational management, resource management and project management; and (3) the model developed should be adopted for use at Umgeni Water for the delivery of projects to minimise project delivery challenges.