Theses and dissertations (Engineering and Built Environment)

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Analysis of the viability of additive manufacturing for rapid tooling: A case study for the plastic industry
(2022-05-13) Pancha, Uttam Bhana; Olanrewaju, Oludolapo Akanni
The current environment of changing market trends that include mass customization, sustainability, environmental impact and localized production drives the manufacturing industry to strive for additive manufacturing because of the versatility of the technology. Injection Moulding Company (IMC) is using traditional manufacturing approaches which compromise its competitiveness resulting in decreased production rate and high operational costs due to lengthy changeover times. The aim of the study was to investigate the viability of additive manufacturing technology for the manufacture of moulds to reduce operational costs. ABC mould demand classification analysis conducted for the top 16 moulds revealed that the moulds for the switch cover ranked highest in terms of the demand of moulds that were fabricated by IMC. The value stream map revealed that there was room for improvement in terms of push to pull and frequent lot transfer, standardising work, reducing cutting time and process scrap, as well as introducing poka yokes and cellular manufacturing, and it was proposed to reduce material movements and setup times. Through the deployment of group technology and rank clustering algorithm, three mould families and three machine cells were derived. As a result, the mould fabrication process was improved by reducing material movements and reducing setup times. Analytic hierarchical process was deployed as criteria for comparison and selection of the best 3D printing technology from among the recent additive manufacturing (AM) technologies that would meet surface finish, dimensional accuracy, cost, and manufacturing lead time requirements. Four AM options included Multilevel Concurrent Printing, MELD technology, Metal Jet 3D printer, and VELO3D. The final results indicated that the VELO3D is better than other additive manufacturing technologies for rapid tooling for the manufacture of moulds. The switch cover mould was then assessed for viability of fabrication through AM. The research proposed a process for evaluation of investment in VELO3D machine. A final decision was made through the comparison of AM technology, VELO3D versus traditional manufacturing capabilities in tool production. The traditional manufacturing was found to be characterised by a huge mould cost which was absent when additive manufacturing technology is adopted. The results demonstrated that VELO3D outperformed the traditional approach from a cost perspective leading to an 80% overall cost savings from the adoption of AM.
Application of optimal control for power systems considering renewable energy technologies
(2021-03) Chetty, Dhanpal; Sharma, Gulshan; Davidson, Innocent Ewaen
Over the last decade, power generation from renewable energy sources such as wind, hydro and solar energies have substantially increased globally and in South Africa. Of all the renewable energy sources, wind energy appears to be the most promising, considering design and costs. However, due to the intermittent nature of wind, the increased integration of wind energy into existing power systems raises several control challenges related to load frequency control (LFC) and tie-line power system stability. The stability of modern power systems, incorporating wind energy generations, will be significantly enhanced with the development of LFC strategies based on modern control theory, which is the focus of this research. This thesis presents the design, modelling and analysis, of two LFC control strategies for interconnected power systems, having wind power integrations. The first design is an optimal control strategy, based on error minimization through full state vector feedback, for a two-area interconnected power system consisting of hydro-thermal generations. The second design is a model predictive control (MPC) strategy, based output vector feedback of system state parameters, for a two-area interconnected power system consisting of thermal generations in each area. Both designs include the active power support from doubly fed induction generator based wind turbines (DFIG) in conjunction with the combined effort of a thyristor control phase shifter (TCPS) and super conducting magnetic energy storage unit (SMES). Both control strategies were simulated in MATLAB Simulink and positive results were obtained. The results show that the optimal control strategy is enhanced with power integrations using DFIG based wind turbines combined with the TCPS-SMES units and the MPC strategy is very robust and provides better dynamic performances even with parameter variations and generation rate restrictions.
An appraisal of building information modelling technology in building construction and maintenance in Africa : a case of Nigeria and South Africa
(2023-05) Toyin, James Olaonipekun; Mewomo, Modupe Cecilia
Building Information Modelling technology (BIM-T) continues to gain attention. Its adoption creates a platform that allows the built environment professionals to share project information through a common database. At the same time, there is an increased perception that implementing BIM on construction projects will positively influence building production throughout its lifecycle. Recent studies have revealed a low level of BIM implementation in the African construction industry. Currently, the utilisation of BIM for building production has received a significant acceptance rate in developed regions, while in African countries, it is still at an infant stage. Moreover, previous studies have established that BIM application comes with various barriers. These barriers contribute to its low adoption, application and implementation. Nevertheless, there are still some notable benefits and impacts on building production, which have been the main drivers for its continual adoption. Therefore, this study aimed to research BIM-T applications in African countries, focusing on the Nigerian and South African construction industries. The goals are to assess its level of awareness, usage, barriers hindering its application/implementation and benefits accruable with its adoption. BIM impacts the building production lifecycle and determines the strategies to promote its application among construction professionals for sustainable construction in developing countries. To achieve the objective of this research, an extensive review of the literature was conducted on usage, barriers to BIM adoption, application/implementation, benefits of adopting BIM, its impacts on building production, and strategies to promote its application/implementation. A structured questionnaire elicited constructive data from the Nigerian built environment professionals (NIA, NIOB, NIQS, and NSE) and the South African construction-related professionals (SACPCMP). The web-based (Google form) questionnaire was distributed online. According to the distribution among the professionals, 276 and 105 respondents indicated their willingness and availability to participate in the research from Nigeria and South Africa, respectively. The generated data was analysed using the following descriptive measures: mean item score (M.I.S), relative important index (RII), ranking and frequency and quantitative inferential analysis (factor analysis, pairwise comparison, one-way ANOVA and Kruskal-Wallis). It was found that there is a significant increase in the level of BIM awareness among Nigerian and South African construction professionals compared to previous findings. 98.55% and 96.19% of respondents, respectively affirmed that they are aware of BIM. Nevertheless, these findings established that there are still BIM-related barriers peculiar to both countries; the top common three barriers are low computer skills among some of the professionals, habitual resistance to change from the traditional style of design and build, and government's unwillingness to support BIM use. These barriers could be responsible for the professional’s low level of BIM tool usage. The study also revealed that all 13 identified BIM benefits are significantly important in both countries. From this, it could be concluded that BIM application has significantly improved the production of buildings through its contribution to performing tasks from building design to post-construction stages. Finally, the respondents identified the need for foundational knowledge in an educational institution on BIM tool use and its applications as a critical area of focus that could assist the promotion of BIM. This study has extensively documented the various research contributions carried out in this study's area of focus. The preliminary survey result concludes that the findings will assist the professional body in making intelligent decisions and adequate measures to advance the adoption, application/implementation of BIM among their members. It will also inform the institutions about what is required from their construction graduates to improve their employability in the industry.
Appraisal of career development among female professionals in the South African construction industry
(2022-05-13) Zungu, Hlumelo T.; Aiyetan, Olatunji Ayodeji; Mewomo, M. C.
Every human being aspires to attain to the top of his or her career. Failure results in dissatisfaction, poor productivity, and lack of interest and proper engagement in the career. The study aims to appraise career development (CD) among female professionals in the construction industry in South Africa. The study was conducted among registered female professionals in the SA construction industry. The purposive sampling technique was employed in reaching the sample. The sample frame comprised of registered female professionals within the South African Council for Project and Construction Management Profession (SACPCMP). The total number of registered professionals is 158 and the whole population was taken as the sample size. The questionnaire to the study was administered to the respondents online using Google forms survey. A total of 67 questionnaires were returned filled, representing 42.4% achieved rate.The inferential statistics was used for data analysis. The findings indicated that gender discrimination has a significantinfluence on females’ participation in CD in the construction industry. Training and continuing education in the construction industry’s influences contribution to CD for female professionals, family, and social commitments are impediments to career development for female professionals. Passion mostly motivates the interest in the career choice of females in the construction industry and the factor that most enhances the successof female professionals in career development is education. Recommendations include that policies put in place should be such that women are represented at all levels and the opportunities are granted fairly to ensure that females are not discriminated against. Provision for training programs be made and salaries for femaleprofessionals should be adjusted such that there is an allowance to cater for domestic assistance. Females should pursue or obtain higher degrees to be successful in career development in the construction industry. These qualifications are such that females couldbe placed in managerial positions. Therefore, the following post-graduate programs are recommended: Construction Management, Human Resource Management, Industrial Psychology, and many others
Assessing the current live fire training structure environment in Ethekwini using CFD
(2020-03-12) Clarke, Thomas Benjamin Bayliss; Walker, Mark; Mendham, Frank
eThekwini Fire and Emergency Services currently uses a repurposed structure to train their firefighters. This study identifies fire related hazards for trainee firefighters when using the ground and first floor of the existing structure. The purpose is to prevent shortcomings being repeated in the design of future firefighter training structures. The fire related hazards have been identified by using Computational Fluid Dynamics (CFD) to simulate fires in the existing structure. The fundamentals of CFD, as well as the selected CFD based fire model, have been summarized. CFD is selected due to its flexibility, accuracy, and cost effectiveness [1]. The Fire Dynamics Simulator (FDS) is the selected CFD based fire model as it has been extensively validated in the past decade [2], which is an important factor should the CFD code claim any credibility [3]. It was developed by the National Institute of Standards and Technology (NIST) to model fire driven fluid flow. It does this by numerically solving a form of the Navier Stokes equations appropriate for thermally driven low Mach flow [4]. Appropriate inputs required for FDS were investigated specifically for live fire training structures. A unique heat release rate (HRR) was investigated and subsequently proposed for a fire on both the ground floor and first floor. The HRR was assessed to find a rate that will be safe from inducing ventilation-controlled conditions and therefore preventing the occurrence of an explosive backdraught. This was investigated by monitoring the effect of the existing structure on a t-squared fire. A t-squared fire uses a selected growth coefficient to estimate the fire’s HRR when the data on the actual fire is not available. Also, the suitability of selecting the emissivity of soot for surfaces was investigated. This was done because it is expected that there would be residual soot deposits in the existing structure. The investigation used the soot modelling capabilities of FDS. This identified the soot density on exposed surfaces and provided an indication on the number of fires required to cover the majority of the exposed surfaces with soot. The simulations performed in this study were within the required validation range. This included using a selected numerical grid size that was within the validation range for the plume resolution index. There is a range of grid sizes that are valid for the plume resolution index and so to assist in the selection of a suitable grid size from the range of valid grid sizes, the implications of time constraints to complete a simulation were investigated. The investigation compared the accuracy of FDS results when having to restart the simulation multiple times due to limited computer access time, with the accuracy of FDS when using a coarser grid. From the fire induced environment, the heat flux and gas temperature were estimated to assess the safety of training firefighters. After examining past firefighter deaths, it was considered necessary to include normal civilian tenable limits in the study to identify the time to incapacitation should mistakes occur during training. The structure’s surface temperature was also measured to assess possible structural damage due to the concern that the existing structure has been damaged from repeated heating and cooling.
Assessment of emerging technologies enhancing project delivery among medium and large construction firms in Durban
(2022-07) Mchunu Johannes S’thembiso; Anugwo, Iruka C.
The objective of this research was to assess the potential of emerging ICT technologies to enhance construction project design, procurement, and delivery among medium and large construction firms registered on the Durban Construction Industry Development Board (cidb) under grade 4-6 and grade 7-9 c. The study explored how construction companies can use various emerging Information and Communication Technology (ICT) technologies such as Internet of Things (IoT), 3D Printing, Virtual Reality (VR), Building Information Modelling (BIM), Robotics and wireless sensor technology, to improve construction project delivery in the eThekwini region. This study focused on one province, KZN and the eThekwini District Municipality, located on the east coast of South Africa. The questionnaires were formulated to evaluate construction contractors’ level of awareness, understanding, knowledge, and commitment to advance business operations using new emerging technologies presently linked to the Fourth Industrial Revolution (4IR). Data collection instruments used for this study comprised an online survey as well as paper-based questionnaires. The data was analysed using percentages, mean scores, and standard deviations, and each question was ranked using the SPSS Statistical Package. The analysis shows that awareness, and knowledge of, new emerging technologies among construction companies in Durban was significantly high within offices. However, awareness, and knowledge of, new emerging technologies was significantly low on construction sites. The study revealed that a remarkable number of respondents were of the opinion that the implementation of emerging ICT technologies and the 4IR would benefit project design, procurement and construction delivery. The study concluded that there is a high level of commitment to implement new emerging technologies among construction companies in Durban. The study recommended that construction companies in Durban should acknowledge the need to enhance business processes in construction and improve levels of performance and competitiveness by implementing new emerging technologies on construction sites. The study proposed that construction companies in Durban should implement new emerging technologies to improve the performance of the sector in KwaZulu-Natal.
Automatic speech recognition of the isiZulu language
(2021-12-01) Shezi Nokwanda; Reddy, Seren
A key component of artificial intelligence is human-to-machine communication. Such communication has been realised through virtual assistants such as Apple's Siri, Google's Now, Amazon's Alexa, etc. This technology is made possible through Automatic Speech Recognition (ASR). Only in recent years have the previously marginalised or developing countries started researching ASR for their indigenous languages. This research focuses on ASR in isiZulu, which is one of South Africa's most spoken indigenous language. The research involves two main fields of study i.e., digital signal processing (DSP) and machine learning (ML). DSP was applied in word boundary estimation and feature extraction. Machine learning was used to convert the work boundary estimation and feature extraction. Machine learning was used to convert the word boundary estimation problem to a classification problem as well as for word recognition. Word boundary estimation achieved an accuracy of 68.4%, which is on par with the current research. the Mel-frequency cepstrum coefficient (MFCC) was used for the feature extraction of the speech and deep neural networks were chosen for the ML component. For the detection and classification of a word in a sentence, the trained neural network was tested by considering the effect of including and excluding explicit boundaries on the overall recognition. Word recognition accuracy with manually demarcated boundaries was 78.18%. In sentence recognition accuracy achieved without demarcated boundaries was 17.74% while a 23.28% accuracy was achieved without demarcated using classification. While in-sentence recognition accuracy for the two algorithms was both low, the accurately recognised words were determined by different heuristics. Other factors, such as the complex differences between the indigenous isiZulu languages and other more commonly spoken languages, are also highlighted and further research avenues are proposed.
Basic mathematical modelling for polymer woven fabric performance suitable for low energy filtration systems
(2019) Mncube, Blessing Thokozani; Rathilal, Sudesh; Pillay, Visvanathan Lingamurti
Water is one of the most important and essential resources that people usually misuse and take for granted until it is either gone or unsuitable to be utilized for domestic, industrial or agricultural purposes. The need to explore affordable purification technologies is essential. The filtration processes are innovative technologies that can be employed in water treatment systems or water purification technologies. However, the filtration technologies have one prime limitation factor of which is fouling and biofilm formed on the membrane surface sometimes internal. Recent advancements in polymer science and textiles have led to developing fabric material that can be used as membranes suitable for emerging economies. For years’ people do use fabric to purify river water especially women from rural areas. Yet non-woven materials are used as a membrane by industries as compared to woven fabrics. However, most non-woven fabrics are easily damaged when cleaned with a polymer brush and require periodical replacement. The tapeline and filter manufacture use a woven fabric as a backer before casting or putting a filter on the weave fabric. These prove the fact that any woven fabric can be modified for optimal use. On the other hand, most Engineers and scientists have not given much attention to woven fabrics as a result, woven fabrics are not employed as membranes. Some scientists and engineers believe that woven fabrics are not suitable for treating water for domestic use. Some believe that some woven fabrics can be used as membranes provided they are capable to remove unwanted materials like bacteria and pathogen. The aim of this study is to create a full understanding of the factors that affect the fabrics when used as membranes, especially when the polymer woven fabrics are used as filters to treat water and wastewater. It is essentially important to develop standardized procedures or models that accurately describe the textile woven fabrics behaviour when used as filters. The standardized models or procedures will assist engineers and scientists when developing filtration systems using woven fabrics. The first objective was to evaluate and compare the fabric types that can be used as filters or membranes in water and wastewater treatment processes. The second objective was to identify the applications for woven fabric membranes and evaluate the factors that play a critical role during the filtration process and relationship between those factors. The experimental investigations conducted were to evaluate the (1) main objectives; (2) effect of membrane orientation; (3) effect of feed quality on membrane performance; (4) effect on stable flux quality and quantity of the selected fabrics; (5) effect of fabric type on filtration or microfiltration processes; (6) effect of membrane fouling on membrane performance; (7) develop the basic model suitable in identifying the right fabric for any filtration system operating at low energy. The experimental investigations conducted were to evaluate the selected woven fabrics that were manufactured in South Africa, easy to clean with a polymer brush. Those woven fabrics were tested using South African river water and wastewater from treatment plants. When evaluating different feed solutions, bio-fouling was considered to be the major limiting factor of woven fabrics, but the feed with a lot of bio impurities can be modified for optimization processes. Laboratory apparatus and field apparatus was developed to analyze and evaluate the effect and behaviour of fabrics performance, and cake formed on the fabrics. The result clearly states that a solution or wastewater with a lot of biological organisms produce lower flux and also produces a lower critical/stable flux when compared with the solution with more incompressible solids or impurities. The result clearly shows that all selected fabrics can be used as filters however; the polyester fabric was the only fabric that can be used for microfiltration processes suitable to clean water for domestic use. This polyester fabric removes 99.995% of impurities from the polluted waters. The Permeate water quality coming from this polyester fabric was less than 1NTU, before and after stable flux. Other fabrics can be used as filters but not for microfiltration. These three fabrics are not capable of removing micro-impurities (less than 20 micrometres). The basic mathematical modelling Equation developed, proved that the membrane pore size, driving force, impurities size in polluted water, impurities nature and impurities concentration play major roles in the filtration process especially in stable flux formation. The simple Equation F = Ae−Bt + C was discovered to be suitable to evaluate the fabric performance, where C is the constant flux value, A is the maximum flux value and B is the part of the critical area or rate change. The Equation can be applied to most fabrics that are used as filters. Testing the maximum flux value was critical and achievable when using pure and clean water especially the distilled water. The results show that most solutions with high compressible impurities will take less time to reach a critical or stable flux. The solution or effluent or river water with more bio impurities and more bacteria will have less flux when compared with a solution with more incompressible impurities. Most polymer woven fabrics do not require any sophisticated technologies or additional chemicals to clean. It can be easily brushed with a polymer brush. Brushing the surface of the fabric with balanced tensile strengths in both warp and weft yarns will not rearrange, damage, or affect the pore size. Only sharp objects can damage the polymer fabrics. The knowledge of this report will assist in optimising the filtration system operation at low energy when using woven polymer fabrics as membranes for filtration. The basic mathematical model can be useful to engineers and scientists willing to use woven fabrics as membranes. Hence, mathematical modelling is one of the important tools of engineering optimization and design. This study focuses on the low energy (gravity-driven) systems that treat water and wastewater like Household Point of Use (POU) systems. Other POU systems were tested and compared to POU systems that are made of the Polymer woven fabric. Based on results, it can be concluded that POU's that uses polyester membranes (PWF-POU) are good prospects for area without sophisticated water or wastewater treatment systems since it removes almost all bacteria and impurities. Polyester woven fabrics can be used as a microfiltration membrane not only to process water or wastewater but also to process chemicals, oils, etc. The other selected fabrics that were made of polypropylene filaments need to be modification in order to operate at optimum when cleaning water for domestic and tertiary use. When modifying these polypropylene fabrics, the quality do improved.
Characterisation of concrete with expanded polystyrene, eggshell powder and non-potable water : a case study
(2023-05) Mncwango, Bonke; Allopi, Dhiren
Urbanisation has brought many benefits but it has also highlighted the global lack of housing alongside global natural resource scarcity. Lack of housing on the surface appears to be a singular problem, however in reality it represents a number of society’s biggest challenges such as crime, pollution (as a result of inadequate waste disposal strategies), unhygienic living conditions, as well as numerous health problems. Governments across the world have made various attempts at addressing the issue of lack of housing, including embarking on large scale social and public housing initiatives, building smaller homes for the homeless, as well as removing certain regulatory barriers to allow more houses to be built at a reduced timeframe. These advances have assisted many individuals and families globally, however, there are still many individuals and families that government housing-aid or housing initiatives have not yet reached. These individuals and families are faced with solving their housing crisis on their own, with their own resources. Globally, concrete remains a supreme building material in the construction industry and therefore is a primary factor of consideration for solving the housing crisis, especially for those who have no financial assistance or aid from government. Concrete’s composition is simple: cement, fine aggregate, coarse aggregate and water. The intricate interaction between all four components is meant to stand the test of time. Unfortunately, it is not only the earth’s diminishing natural resource reserves which are causing a decline in the popularity of conventionally produced concrete, but it is also the irreparable harm that it is causing to the environment. The process of concrete production requires large volumes of cement, and cement remains one of the biggest producers of carbon dioxide. Carbon dioxide is a greenhouse gas which in excessive amounts creates a cover that traps the sun’s heat energy in the atmosphere. Another major criticism of conventional concrete is the requirement that it be produced with clean water which is of a drinkable standard. This criticism is justified when considering the extreme water shortages that are experienced by many low to middle income countries around the world. The amount of financial and human resources that local authorities invest in cleansing water to bring it to a drinkable standard is often overlooked. It is obvious that it is less expensive to use water directly from a river in its natural state than using it after it has undergone numerous cleansing processes by local authorities. There have been a notable number of advances in making concrete more resource-efficient and environmentally friendly. These include the advent of lightweight concretes such as expanded polystyrene concrete. Expanded polystyrene concrete not only saves the amount of aggregate that would normally be required in conventional concrete, it also has excellent acoustic and thermal properties, thereby reducing energy consumption which in turn saves money. However, even with such excellent properties, expanded polystyrene concrete still fails to address two of concrete’s major criticisms which are related to the amount of cement used as well as the amount of clean potable water required for mixing. Therefore, by building on the qualities of expanded polystyrene concrete, this research investigates the potential of lowering the amount of cement required in a concrete mix through the use of eggshell powder. Eggshells are a waste product found everywhere in the world and are readily available in almost limitless quantities. The use of eggshells in concrete to lower the amount of cement required will not only achieve a reduction in the amount of carbon dioxide that is produced in the process of producing concrete, it will also assist in contributing toward solving the escalating waste disposal crisis that currently exists for many waste types such as eggshells. It is common for communities to reside close to a river or a natural flowing watercourse, so this research included river water as a variable. Four different concrete mix scenarios were tested to ascertain through experimentation whether the strength properties of concrete that contains expanded polystyrene, eggshell powder and natural river water in various proportions could in any way compare to a conventionally produced concrete mix. In order to comprehensively study material behaviour in this case, sieve analysis, bulk density, fineness modulus, moisture content as well as specific gravity tests were performed on all aggregates used. Furthermore, in order to achieve the required analytical depth for the materials being studied, x-ray diffraction and energy dispersive spectroscopy tests were conducted. As a means of conducting further trend analysis on the different experimental mixes, logarithmic regression models were developed. Through analysis of the output attained from the aforementioned strategies, this research study found that when cement was substituted by eggshell powder at a percentage of 5 % and simultaneously when coarse aggregate was also substituted by expanded polystyrene at a percentage of 5 %, all mixed with non-potable water, the compressive and flexural strength outcomes marginally differed from the strength outcomes of conventionally produced concrete. Furthermore, the substitution of stone by EPS at a percentage of 10 % when mixed with river water was comparable to the substitution of stone by EPS at a percentage of 10 % when mixed with potable water. The results showed that there was a difference of not more than 1.4 MPa and 0.3 MPa in compressive and flexural strength respectively amongst the averages obtained at each age tested. Study results show that the substitution of potable water by non-potable water reduced both the compressive and flexural strength of the concrete when the mix did not contain eggshell powder. However, when eggshell powder was included in the mix, the strength outcomes of the compressive and flexural strength of the concrete mix was comparable to that of conventionally produced concrete. There may be many reasons why it is important to not deviate from convention in the production of numerous products such as concrete; nevertheless, the value of experimentation as demonstrated in this research is that experimentation can give rise to a variety of innovations accompanied by a wealth of solutions to the environmental and socio-economic issues that the world is currently faced with.
A comparative study of the construction of road formation layers using labour-intensive versus traditional mechanistic methods on road 1264 in KZN
(2022-05-13) Mkhize, Mongezi S.; Walker, Mark; Mckune, Tom
The urgent need to upgrade and construct roads in South Africa is one of the many critical utility provision challenges faced by the municipalities, consultants and departments involved in road construction. The biggest challenge that is faced by the government is to minimise unemployment and increase skills transfer through the training of inexperienced local communities on road construction. The road can be constructed using traditional mechanistic methods (TMM), commonly known as plant machines, which makes more use of plant machine than labour. On the other hand, the road can also be constructed using the labour-intensive construction (LIC) method which utilises more labour involvement during construction and minimal machine usage. The purpose of this research is to provide insight into the time and cost comparison between LIC and TMM of constructing road formation layers. Road D1264 in Bergville, KwaZulu-Natal will be used as a case study in the research to compare the difference between labour-intensive and traditional mechanistic construction of road formation layers, using cost and time to reach the same quality. This research aims to promote the use of LIC roadbed construction to be used more frequently in the road construction industry in South Africa. The Expanded Public Works Programme (EPWP) encourages road construction to be undertaken using labour- intensive methods to allow unemployed people to be given more job opportunities. Municipalities, consultants and departments involved with road construction will be assisted through this research in making informed decisions and selections thereafter of the most reliable road formation construction method in terms of time and cost. Available cost, time and quality data from the Road D1264 will be used to compare the construction of road formation layers using LIC versus TMM in KZN. The decision making process will lie in the hands of the municipalities and consultants based on the cost and time required to complete the project. Furthermore, a quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at the road construction technical experts in the Department of Transport, Department of Works, consultants and the roads departments of districts and local municipalities. The results of the survey questionnaires revealed that the road construction experts agree with the finding of this study that LIC is more expensive when compared to TMM. LIC is also more time-consuming than TMM. LIC and TMM produce the same quality. The survey questionnaire revealed that South Africa may be advancing over the years in the use of LIC methods; however, more education in the form of training, seminars and other methds of marketing must be undertaken, starting at the universities, municipal level, the Department of Transport, Department of Works, and consultants. The comparative research in this study using the available data from Road D1264 revealed that during the construction of the road formation layers, using LIC is more expensive when compared to TMM. LIC is also more time-consuming than TMM. LIC and TMM produce the same quality. But it cannot be ignored that LIC creates employment particularly for women, youth and the disabled within the community. LIC maximises the use of local materials and plant owners as suppliers of goods and services. LIC can be the country’s solution to unemployment and porvety.
A comparative study of trenchless technologies versus traditional open trenching for the replacement of ageing potable water pipelines
(2014-06-13) Hay, Shanley; Macleod, Neil A.; Walker, Mark
The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.
Coordinated control of conventional power sources and plug-in hybrid electric vehicles for a hybrid power system
(2022-05) Adbul-Kader, Mohammed Ozayr; Akindeji, Timothy Kayode; Sharma, Gulshan
Globally, the requirement for renewable and clean energy technologies is becoming vastly popular. With the high implementation of solar and wind energy systems, together with plugin hybrid electric vehicle (PHEV) aggregators, energy costs can be minimised, greenhouse gas emissions decrease, and overall maintenance becomes reduced. The constant increase of load demand is becoming a challenge for the current power systems, with difficulties including stability concerns and excessive regulations by the government. Due to irradiance and wind speed fluctuations, the solar and wind energy system’s non-linearity affects the existing power system stability. The growth of the electric vehicle industry has also shed new light on potential auxiliary services that can be provided, as and when required, to the power system. Hence, this research examines the potential control strategies that are required to maintain the system in steady-state conditions after disturbances that occur with higher penetration of renewable energy systems (RESs) and PHEVs. The case study models a isolated two-area thermal type power system that is interconnected through an AC tie-line. Three scenarios are modelled, simulated and analysed. The first scenario models a isolated thermal power system with PHEVs with two areas which utilises a fractional order proportional integral derivative (FOPID) controller in each area. The resulting model is analysed to see the effects of PHEVs coupled with FOPID on the power system. The second scenario models a isolated two-area thermal power system with RES and utilises a fuzzy type-2 (FT2) FOPID controller in each area. The RES penetration istested for its non-linearity effect on the isolated power system, and the error is reduced by an advanced controller that uses artificial intelligence techniques. The third scenario is modelled as an isolated two-area thermal power system with PHEVs and RES coupled with neural network predictive controller (NNPC) in each area. The three scenarios are simulated in MATLAB/Simulink with results displayed graphically and numerically. The results show that the integration of PHEVs for load and/or storage in the multi-area power system, and the proposed control methods for each scenario, have the best dynamic response with the least error, no oscillations and the fastest response to steady state condition.
Development of a mathematical model for treatment of metal finishing wastewater
(2008) Mbongwa, Nkosinathi Wiseman; Telukdarie, Arnesh
The waste generated by metal finishers is rated as the most toxic and harmful to the environment. Metal finishing wastewater consists of heavy metals, cyanides, acids and alkalis. Formal treatment of waste generated has not been of primary importance to metal finishers. It would be ideal to develop a generic model to assist finishers to predict the effectiveness of wastewater treatment. The model must be able to predict effectiveness of treatment based on a variety of equipment, chemicals and concentrations.
Distributed generation optimization in future smart grids
(2022-09-29) Chidzonga, Richard Foya; Nleya, Bakhe
Ever-surging global power(energy) demands coupled with the need to avail it in a reliable, as well as efficient manner, have led to the modernization of legacy and cur-rent power system grids into Smart Grid (SGs) equivalents. This is mostly achieved by blending the existing systems with an information subsystem that will facilitate duplex communication, i.e., electrical power flowing towards the end users while information characterising the grid’s performance can also be relayed, mostly in the reverse direction. Thus, the information subsystem interconnects other core (key) entities such as generation, distribution, transmission, and end-user terminals to interrelate in real-time, and in the process, achieving a well reliable, robust as well as efficiently managed SG power system. As such, in the emerging distributed power systems of the future, Demand Side Management (DSM) will play an important role in dealing with stochastic renewable power sources and loads. A near-unity load factor can be secured by employing De-mand Response methods with storage systems as well as regulatory control mechanisms. Increasing deployment of Renewable Energy generation and other forms of unconventional loads such as Plug-In Electric Vehicles will aid DR implementation with attendant better results for both prosumers and the utilities. The central objective of DSM is to minimize peak-to-average ratio (PAR) and energy costs by switching to cheaper RES as well as reduction of CO2 emissions. This work focused on emergent techniques and microgrid optimization with special attention to load scheduling. Techniques for DSM, mathematical models of DSM, and optimization methods have been reviewed. State-of-the-art methodologies entering the DSM mainstream are data science, advanced metering infrastructure, and blockchain technologies. An improved atom search optimization technique is applied for DSM to substantially reduce power and energy costs in typical standalone or grid-tied microgrids. Further the day ahead dispatch problem of MGs with DEGs subject to a non-convex cost function is solved and simulated using quadratic particle swarm optimization. In the later case, the objective function includes the DEGs ‘valve-point’ loading effect in the ‘fuel-cost’ curve. The impact of DSM on convex and non-convex energy management problems with different load participation levels is investigated. Ultimately, it is demonstrated that the quadratic particle swarm optimization algorithm efficiently solves the non-convex energy management system (EMS) problem. In addition, we propose a hierar-chical optimal dispatch framework that relies on several objectives to achieve the overall design goal of a reliable and stable power supply, coupled with economic ben-efits to prosumers who elect to participate in power trading. Evaluation of the pro-posed framework is carried out analytically and by way of simulation. Overall, it is deduced from the obtained analytical as well as simulation results that the combination of appropriately sized battery storage systems (BESS) and renewable type generators such as PVs and WTs will help achieve a stable and reliable power supply to all users in the SG (or MG) and at the same time, it affords resilience. Final-ly, in our closing chapter, we also spell out possible future research directions.
Distribution network performance analysis with high penetration o RTPV and Bess
(2020-11) Reddy, Rodney; Davidson, Innocent Ewaen; Chetty, Dayahalan
The consequential effect of meeting electrical demands continues to burden the South African electrical infrastructure. Electrical violations tend to constrain a power system’s ability to supply suitable energy whilst meeting growth demands. Often optimization techniques are utilized to reduce violations, however; constrained networks in dense and radial distribution systems don’t have any quick or short-term solutions. This thesis explores solar rooftop photovoltaics (RTPV) and battery energy storage systems (BESS) as a distributed energy resource to alleviate violations which are currently constraining medium voltage (MV) networks. This research has studied the influential effect of hybrid RTPV systems, with and without BESS. The analysis, simulated with actual all-day load profiles, has uniquely considered RTPV installations for every residential customer connected to an MV network. For the identification of networks that experience violations; informative analysis-results from over eight hundred MV feeders have been studied. These results have been utilized to develop a methodological approach for a technical priority ranking system. This system helps to categorize the severity of network constraints for distribution networks. By modelling a case study, this thesis demonstrates what impact RTPV will have on a technically violated/constrained MV network. This thesis offers an alternative network optimization solution by using RTPV and BESS to address constrained/violated networks. This can assist Utilities to meet electrical demands while complying with statutory regulation limits.
The effect of heavy metal composition on the performance of sugarcane bagasse as an adsorbant in water treatment
(2021-04) Buthelezi, Nokulunga Priscilla; Isa, Yusuf Makarﬁ
Wastewater produced by the industries is potentially harmful to the ecosystem because of various contaminants like heavy metals that find their way into soil and water supplies. Industrial waste constitutes different kinds of metal which contaminate natural water. Heavy metals can build up in the environment and enter living organisms through chain elements such as the food chain and therefore, pose a major health risk to living organisms. The situation has been worsened by the absence of broadly accepted heavy metal treatment techniques, thus this challenge continues to receive considerable attention from stakeholders including scientists and researchers. While many technologies have been proposed such as reverse osmosis, flocculation, ion exchange and so on and so forth, they continue to suffer from a number of drawbacks including generation of secondary wastes and cost ineffectiveness. Thus, in the present study, adsorption was chosen as a cost effective, efficient, and environmentally friendly treatment process. Sugar cane milling production produces a lot of sugar cane bagasse which is considered as environmental waste if not disposed properly. It is imperative to remove heavy metals from polluted water before discharging it into the environment, rivers and lakes using sustainable techniques. Heavy metal removal from wastewater using low-cost adsorbents like sugarcane bagasse addresses two problems: removal of pollutants from water and utilization of agricultural waste. This study evaluated the performance of sugarcane bagasse in the removal of heavy metals. Sugarcane bagasse was characterized to determine the functional groups, the porosity and surface area, crystallinity and morphology using FTIR, SEM and XRD. One factor at a time (OFAT) approach was used to evaluate the effect of operating parameters on the removal of heavy metal ions. A 3-system component of the stock solution of synthesized wastewater namely single, binary and ternary were studied. The 3 metal ions evaluated were Copper, Chromium and Cadmium. The factors considered in the OFAT design of experiments were contact time (30-240 mins), adsorbent dosage (5-30g/L), initial concentration (50-500 mg/L), pH(2-9), and particle size (75-600 μm). It was observed that all adsorption parameters had an effect on the adsorption rate. However, an adsorption dosage had a greater impact on the adsorption rate. An increase in the adsorption dosage from (5-20 g) showed that the percentage removal efficiency for chromium, copper and cadmium increased from (40-72%, 44-75% and 39-59%) in a single metal system. In addition, the percentage removal increased from (34-62% for chromium, 47- 78% for copper, and 34-62% for cadmium) in a binary metal system. Furthermore, the percentage removal increased from (38-52%, 40-59% and 24-43%) for chromium, copper, and cadmium in a ternary metal system. Adsorption capacity of the adsorbent was determined using the optimal operating parameters obtained from the OFAT design of experiments. Langmuir and Freundlich isotherms were used to analyze the adsorption data. The OFAT design of experiments resulted in producing the optimum conditions for adsorption. The optimum conditions for maximum adsorption were, contact time (180 mins), initial concentration (50 mg/L), pH (7), dosage (20 g), particle size (340-450 μm) and a mixing speed of 150 rpm. Adsorption capacities differed between the 3 system components. Maximum adsorption capacities of 38.41 mg/L were registered for copper ions and was recorded for the single component system. Stock solutions containing copper ions registered the highest adsorption capacity. There was a significant decrease in the maximum adsorption capacities for copper ions of the binary and ternary system components which were 21.45 mg/L and 1.237 mg/L respectively. This was attributed to the co-metal ion dependence in both the binary and ternary system components. In conclusion, the study showed that sugarcane bagasse can be used as an adsorbent in the efficient removal of heavy metal ions present in wastewater.
Evaluation of Kaolinite and activated carbon performance for CO2 capture
(2021-03) Akpasi, Stephen Okiemute; Isa, Yusuf Makarﬁ
Global climate change is one of the major threats facing the world today and can be due to increased atmospheric concentrations of greenhouse gases (GHGs), such as carbon dioxide (CO2). There is also an immediate need to reduce CO2 emissions, and one of the potential solutions for reducing CO2 emissions is carbon capture and storage (CCS). This work investigated the performance assessment of kaolinite and activated carbon (AC) adsorbent for CO2 capture. In particular, the effect of operating parameters such as temperature, bed height, inlet gas flow rate etc. on CO2 adsorption behaviour of the adsorbents was also investigated. Extensive research on the development of adsorbents that can adsorb large amounts of CO2 with low energy consumption has recently been carried out. In CO2 adsorption technology, the challenge is to develop an adsorbent that is not only non-toxic, eco-friendly, and cost-effective, but also has the potential to extract CO2 gas from a mixed gas stream selectively and effectively. Due to the possibility of a potential adsorbent due to its low cost, rich natural abundance and high mechanical and chemical stability, this study proposes kaolinite. As the presence of clay minerals in soils serves as a pollutant collector to enhance the atmosphere, kaolinite has the potential to be an efficient adsorbent for CO2 capture. Kaolinite was investigated as an adsorbent in this research to confirm if it is suitable for CO2 capture. Kaolinite/activated carbon composite adsorbents were synthesized. Sugarcane bagasse was used in preparing the activated carbon (AC). ZnCl2 was impregnated onto sugarcane bagasse during the preparation of activated carbon (AC) to improve the physical properties (surface area, pore size and pore volume) and the CO2 adsorption capacity of the activated carbon (AC) adsorbent developed. The materials were characterized and tested for CO2 adsorption (activated carbon and kaolinite). BET, FTIR and SEM studies were used to classify the adsorbents for their surface area and pore properties, functional groups, and surface morphology, respectively. BET analysis was conducted and the pore volume, pore size and surface area of the adsorbent materials were reported. Functional groups were actively present in the adsorption process. This was verified using FTIR spectroscopy. The kaolinite adsorbent was not feasible for CO2 capture. BET, SEM, and custom-built CO2 adsorption equipment have confirmed this. In contrast to literature, the CO2 adsorption capacity of kaolinite was low. This is due to the fact that kaolinite used in this study is not suitable as adsorbent for CO2 capture as they exhibited a low CO2 adsorption capacity. The results obtained in this study show that temperature, bed height and inlet gas flow rate influenced the adsorption behaviour of activated carbon (AC), kaolinite and kaolinite/activated carbon composite adsorbent during CO2 capture. At 30 0C, activated carbon (AC) exhibited an adsorption capacity of 28.97 mg CO2/g, the highest capacity among all the adsorbents tested. Kaolinite-activated carbon composite adsorbent offered CO2 adsorption capacities of 18.54 mg CO2/g. Kaolinite provides the lowest capacity of 12.98 mg CO2/g. In conclusion, this research verified that CO2 adsorption with kaolinite and activated carbon is favoured at low temperatures, low operating CO2 flowrates and high column bed height.
Examining issues influencing effective facilities management practice on selected public sector buildings in South Africa
(2021-12-01) Ndlovu, Petronella Minenhle; Mewomo, M. C.
The facilities management (FM) industry has been confronted with a number of challenges and obstacles when it comes to the implementation of effective and efficient facilities management in public sector buildings. Thus, this study: investigates the current nature and extent of facilities management practice in public sector buildings; determines the technical roles of the facilities management team in the life cycle of public sector buildings; determines the competencies required for effective FM practices in public sector buildings; investigatesthe challengesinhibiting effective FM practice in public sector buildings, determines the drivers and enablers for effective FM practice in public sector buildings; and also recommends strategies for effective FM in public sector buildings in South Africa. The study utilized primary and secondary data. Primary data was obtained from the respondents through a questionnaire survey of 39 inspectors of the provincial Public Works department in KwaZulu-Natal, South Africa. The questionnaire elicited information on issues influencing effective facilities management practices on selected public sector buildings. The secondary data was generated from literature from which the research instrument was developed. Data analysis was carried out using mean item score, percentage, factor analysis and T-test. The research findings indicated that most organizations were predominantly utilizing unplanned maintenance strategies and as such, involved repair work and corrective maintenance rather than predictive and preventive maintenance. The study also found insufficient funding, irregular, or fixed budgeting and the absence of a policy guideline for infrastructural development and maintenance of buildings as the major challenge affecting FM practices in the study area. The predominant drivers of FM practices are design of organizational structure, spirit of teamwork and sharing of FM knowledge and skills. The availability of policy/regulations supporting the maintenance of public buildings, availability of funds, hiring of better skilled professionals and an increase in the level of awareness of FM benefits were found to be enablers of FM practices. Based on these findings, the study recommends the need to employ a planned maintenance strategy in the day-to-day maintenance of public sector buildings. Furthermore, there is a need to have a policy in place that stands as a guideline for all work, strategies and processes for FM in public sector buildings. This study adds to the existing body of knowledge by providing useful information on factors that could enhance the effectiveness of facilities management in public sectors buildings in South Africa and beyond.
An exploration of funds management by emerging contractors
(2018-01) Merana, Andisa Avuyile; Aiyetan, Olatunji Ayodeji
Finance is a critical aspect that needs to be closely monitored in a business and during the lifespan of a construction project. Emerging contractors need to develop and run sustainable businesses in the construction industry. The extent of expertise in funds management by emerging contractors directly relates to their development. Therefore, all efforts must be geared towards their expertise, development and sustenance. Emerging contractors need to manage their finances, be competitive, and deliver projects in the required quality, time and within the allocated budget. This study aims at determining challenges faced by emerging contractors, the root causes of challenges of emerging contractors in funds management, the impact of emerging contractor challenges on project delivery time. Further, the study aims to develop a flow chart that will mitigate emerging contractor challenges in funds management. The study was conducted in KwaZulu-Natal, South Africa using a questionnaire. Questionnaires were distributed in two phases and respondents to the study included emerging contractors and industry stakeholders. Random and systematic sampling techniques were employed in the selection of samples. A total of 85 questionnaires were analysed for the study. Inferential statistics was employed for analysis of data. Findings include late payment for completed work which ultimately causes delays; interference with project performance; inadequate planning; unskilled site manpower; late delivery of material; late identification of errors and resolution of drawings, specification errors and omissions; community unrest, militancy and communal crises and interference by political leaders are some of the key factors that negatively affect emerging contractors’ funds management. When adequate attention is given to these factors, it results in project success. In addition, improvement of contractor performance and quality of work; involvement of tribal authorities, provision of finances for project by funders, securing finances and materials credit; successfully managing project finances from inception to completion leads to profits being made and projects are completed successfully and within budget when payment for work done is effected on time. Recommendations include ensuring that sufficient finances are secured, allocated and properly managed from inception to completion of a project; payments are prepared, submitted and paid on time. Planning is improved to combat project delays including ordering materials in advance, identifying design and specification errors early, engaging all project stakeholders to avoid disputes and attending formal training courses to acquire skills that will assist in running projects and managing successful and sustainable businesses. It is also recommended that the new proposed programme and flowchart be adopted to assist the South African construction industry in improving the financial management practices and develop skill of emerging contractors; its adoption will alleviate challenges facing emerging contractors in funds management.
Exploring industry's contribution to the labour-intensive construction of low order rural community access roads
(2020) Jairam, Santosh; Allopi, Dhiren
The Government of South Africa supports labour-intensive work methodologies as a means of alleviating unemployment in South Africa. In 2004 the Expanded Public Works Programme (EPWP) was formed to promote labour-intensive work methods due to the high unemployment situation. The EPWP is a nationwide programme using public funds to encourage employment by using labour-intensive work methodologies with the intention of reducing national poverty. The programme covers four sectors. The four sectors are environment and culture, infrastructure, social and non-state. The largest component is infrastructure; roads being part of the infrastructure component provides the highest potential for employment creation. Both international and local experience has revealed that by having trained supervisory staff and a proper employment framework, labour-intensive work methods can be successfully used for projects such as roads, sidewalks, storm water drains, trenches, buildings, sanitation and water. The national government, based on this experience and due to high levels of unemployment, has encouraged the use of these type of infrastructure projects as a way of contributing to the alleviation of unemployment. “Only twelve per cent of the road sector budget is used for labour-intensive projects” (Public Works 2012b: 1). This implies that there have been no drastic changes in the extent to which labour-intensive work methodologies have been used in the road works programme. This study focused on exploring parastatals’, consultants’ and contractors’ contribution to the labour-intensive construction of low order rural community access roads in the Outer West region of eThekwini’s Municipality, KwaZulu-Natal, in accordance with the EPWP Guidelines. The population consisted of 101 individuals from the contracting, consulting and parastatal fields of employment who had worked on EPWP related labour-intensive road projects in this region. All 101 individuals were chosen as the sample size A qualitative and quantitative approach was used in this research to gather data on the contribution made by the civil engineering industry to the promotion of labourintensive road construction methods. This approach allowed for an understanding of the motivation and the experiences of consultants, contractors and parastatals regarding the design and construction management choices they have made. Data was collected via a questionnaire containing open-ended questions and rating scales from 87 civil engineering staff that were employed by parastatals, contractors and consultants who were involved in designing, constructing and managing labourintensive construction of low order rural community access roads in the Outer West region of eThekwini Municipality. In addition, interviews were conducted with same 87 civil engineering staff that were involved in designing, constructing and managing these labour-intensive road construction projects during the period from 2015 to 2019. Data collected overwhelmingly suggested that very little practically is being done to promote labour-intensive construction of low order community access roads. The nature of engagement that does occur is largely through the filling in of basic reporting forms and providing basic small scale informal training and work to labour. No standard specification document is in place to enforce labour-intensive construction of rural community access roads. The documents that are in place merely serve as guidelines and administrative data collection tools rather than helping to promote labour-intensive road construction.