Browsing by Author "Mhlanga, S."

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    Academic staff development strategies in engineering fields of study: case study of Zimbabwe
    (2013-06) Mhlanga, S.; Matope, S.; Mugwagwa, L.; Phuthi, N.; Moyo, V. S.
    Higher education is the basic instrument of economic growth and technological advancement in any society. The economic meltdown in Zimbabwe which climaxed 2008 with an inflation level of 231million % exacerbated the brain drain. After the economic meltdown, Zimbabwe is in the process of rebuilding the quality of staff and the staffing levels in its higher education institutions. The challenge has been the decision on the mode of study: whether to go via taught masters or master's by research; where to allow the faculty members to study: in the region, or beyond; on a fulltime or on a part-time basis or on a split-site basis. These challenges have been due to the need to have a quick but quality programme of staff development, while maximising on the resources available for staff development. A survey was undertaken of the engineering related departments in Zimbabwe universities focusing on the existing staffing levels, their qualifications, current numbers undergoing study and their levels. The challenges faced by each institution from the administrative side and from the staff side are summarised. Recommendations on staff development strategies are given in conclusion.
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    Development of a condition based maintenance system for a sugar producing company
    (2014-07-14) Chindondondo, B.; Nyanga, L.; Merwe, A. V.; Mupinga, T.; Mhlanga, S.
    With globalisation taking centre stage in almost every market; traditionally monopolistic manufacturing companies in Zimbabwe are struggling to compete with international companies whose operations are optimised. This paper focuses on maintenance practises of a Zimbabwean sugar manufacturer with an aim to improve the company’s asset care plans. The company’s current maintenance philosophy and its shortcomings on certain equipment in the plant were identified together with the associated annual maintenance costs. A Pareto analysis on the equipment’s breakdown history was used to determine the conditions that can be monitored using Condition Based Maintenance (CBM); and experiments to establish the feasibility of monitoring these conditions were done. The paper then recommends and proposes a CBM system replete with its three main elements of data acquisition, data processing and maintenance decision making to reduce breakdowns on the subject equipment by at most 76%.
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    Implementation Of A Computerized Balanced Scorecard (BSC) System In A Manufacturing Organisation In Zimbabwe
    (2013) Gwangwava, N.; Mhlanga, S.; Goriwondo, W.
    This modern era’s high technological improvements present manufacturers and other organizations with a plethora of Management Information Systems (MISs) which makes them face challenges when choosing a corporate information system. High initial investment in setting up the information systems make it very difficult for companies to adopt new systems as they come into market before realizing a reasonable return from the previous system. In line with these concerns, a methodology for building a Balanced Scorecard module as a strategic management platform that can be integrated smoothly into already existing information system such as MRP/ERP is presented. The paper uses a case study of a manufacturing company based in Zimbabwe. Various manufacturing based metrics are reviewed with the main intent of showing how these can be tracked in a computerized platform. Sample data extracted from the production system is used to test the built system. The paper shows a methodology for software design, setting up and adopting a BSC system. The proposed approach is used to design a computerized BSC system for the case study company, which incorporates a BSC dashboard for the four main perspectives derived from various operational metrics.
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    Industrial Management & Data Systems POM: a highly visual production and operations management environment
    (Emerald, 1997) Onwubolu, G. C.; Mhlanga, S.
    Reports the development and successful implementation of a computer‐integrated production and operations management system (POM), encompassing schedule activities such as aggregate production plan, master production schedule and material requirements plan, and capacity activities such as financial plan, resource requirements plan, rough‐cut capacity plan and capacity requirements plan, at the planning level. POM’s icon‐menu driven system which associates icons with decision model spreadsheets makes it very user‐friendly, and facilitates the integration of decisions encountered by industrial/ manufacturing engineers and operations managers.
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    INVESTIGATION OF THE EFFECTS OF LUBRICANT FAT CONTENT ON DRAWN COPPER WIRES
    (2013-07) Chiduwa,A.C.; Nyanga, L.; Mhlanga, S.; van der Merwe, A.F.; Kanyemba, G.
    The Lean Manufacturing goal of reducing waste and increasing productivity has made it a necessity to produce good quality products in manufacturing industries at a low cost. In the cable manufacturing companies this can be achieved by optimising the wire drawing process. One way to meet the desired quality of the drawn wires is to improve lubricant efficiency through installation of an automatic, continuous lubricant fat content control system on the drawing machine. The paper shows a method of finding the optimum lubricant concentration for producing good quality copper wires using Taguchi experiments. Taguchi experiments are employed to analyse the effects of different lubricant fat content levels on the tensile strength and lubricant temperature. The results from the experiments indicated that the tensile strength of the wire is affected by low lubricant fat content. The lower the lubricant fat content: the lower the tensile strength drawing lubricant resulting in numerous wire breakages that affect the quality of the final product, namely the cable
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    Major challenges for commercialization of perovskite solar cells: A critical review
    (ELSEVIER, 2025-01-09) Seyisi, T.; Fouda-Mbanga, B.G.; Mnyango, J.I.; Nthwane, Y. B.; Nyoni, B.; Mhlanga, S.; Hlangothi, S. P.; Tywabi-Ngeva, Z.
    Global electricity consumption increases rapidly creating strain on the grid. In contrast, the primary sources of electricity are fossil fuels such as gas, coal, and oil which are non-renewable and limited, resulting in energy crises. Therefore, the global energy crisis remains a big challenge that requires renewable and sustainable solutions. Perovskite solar cell is a type of solar cell that uses a perovskite-structured compound, usually a hybrid organic-inorganic lead or tin halide-based material as the light-harvesting active layer. In the development of perovskite solar cells spanning 2009–2024, exceptional power conversion efficiencies ranging from 3.8 % to 26.1 % have been reported. As such, perovskite solar cells hold significant promise as the next generation of affordable and effective photovoltaic solar cell technology. Moreover, perovskite solar cells have recently gained popularity and presented an excellent commercial opportunity because they are made from readily available and inexpensive raw materials. However, the commercial production and utilization of perovskite solar cells remains immature. It has been shown that perovskite solar cells containing titanium dioxide as the electron transport layer exhibit poor stability, degrading quickly under prolonged exposure to sunlight and humid conditions. These instability concerns are the major drawbacks that threaten efforts that are directed at the commercialization of perovskite solar cells. As such, there are significant efforts to improve the development of scalable fabrication of perovskite solar cells and the establishment of industrial production lines. The main objective of this review is to outline the primary obstacles that hinder the commercialization of perovskite solar cells. Firstly, a brief discussion on the principles of perovskite solar cells is done. Secondly, challenges associated with the commercialization of erovskite solar cells and counterstrategies are discussed. The review concludes by looking at perspectives and prospects highlighting the importance of continued research and collaboration in overcoming challenges to commercialization. We hope that this review will provide useful insights for future research on improving the stability of cutting-edge perovskite devices as they approach commercialization.
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    Performance analysis of immigration operation by discrete event modelling and simulation
    (2009) Gandure, J.; Mhlanga, S.
    Discrete event modelling and simulation were used to analyse the performance of immigration operation in Botswana. The relationships between length of queues of immigrants, queuing time, service time and engagement of duty officer were investigated. Data collected by direct observation and clock-timing of processing immigrant request at an inland office on a normal working day was used to determine whether to increase or reduce the number of serving officers to balance the operations. The findings indicated that the system of operation was balanced or fairly matched by 75 % utilization of the officer, average immigrant queuing time of 4.2 min, and required no changes. The pilot study could be replicated at other boarder posts and airports prior to the expected influx of tourists during the 2010 World Cup Football Competition in South Africa.
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    Reducing maternal mortality: a 10-year experience at Mpilo Central Hospital, Bulawayo, Zimbabwe.
    (De Gruyter, 2023) Ngwenya, S.; Mhlanga, S.; Moyo, S.; Lindow, S.W.
    Objectives: Maternal mortality is one of the major Sustainable Development Goals (SDGs) of the global health community. The aim of the SDG 3.1 is to reduce global maternal mortality ratio considerably by 2030. The objective of this study was to document the epidemiological trends in maternal mortality for Mpilo Central Hospital. Methods: This was a 10 year retrospective study using readily available data from the maternity registers. The International Classification of Diseases-Maternal Mortality (ICD-MM) coding system for maternal deaths was used. Results: The maternal mortality ratio (MMR) declined from 655 per 100,000 live births in 2011 to 203 per 100,000 live births by 2020. The commonest groups of maternal mortality during the period 2011–2020 were hypertensive disorders, obstetric haemorrhage, pregnancy-related infection, and pregnancies with abortive outcomes. There were 273 maternal deaths recorded in the period 2011–2015, and 168 maternal deaths in the period 2016–2020. There was also a decline in maternal deaths due to obstetric haemorrhage (53 vs. 34). Maternal deaths due to pregnancy-related infection also declined (46 vs. 22), as well as pregnancies with abortive outcomes (40 vs. 26). Conclusions: There was a 69% decline in the MMR over the 10 year period. The introduction of government interventions such as malarial control, the adoption of life-long Option B+ antiretroviral treatment for the pregnant women, the training courses of staff, and the introduction of strong clinical leadership and accountability were all associated with a significant decline in the causes of maternal deaths.
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    Scheduling linearly deteriorating jobs on parallel machines: a simulated annealing approach
    (2001) Hindi, K.S.; Mhlanga, S.
    Scheduling deteriorating jobs on parallel machines is an NP-hard problem, for which heuristics would be the ®rst solution option. Two variants of linearly deteriorating jobs are considered. The ®rst is that with simple linear deterioration, i.e. where there is a deterioration rate only, which is meaningful only if the jobs are assumed to be available at a positive time t0 . In the second variant, there is a basic processing time and a deterioration rate and all jobs are available at time t ˆ 0. In both cases, we seek to minimize the makespan. Starting from simple heuristics, both steepest descent search and simulated annealing are designed and implemented to arrive at optimal or near-optimal solutions. Computational results for randomly generated problem instances with diåerent job/machine combinations are pre sented.
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    Towards the implementation of e-manufacturing: design of an automatic tea drying control system.
    (2014) Mabvuu, N.; Nyanga, L.; van der Merwe, A. F.; Matope, S.; Mhlanga, S.
    Many of the production costs for producing tea are attributable to the process of drying the tea. E-manufacturing can assist companies to reduce these production costs by making crucial information available to decision-makers so that they can make informed decisions. This paper presents an application of e-manufacturing to the design of an automatic tea drying control system. This control system will ensure that the multiple drying parameters such as temperature, dryer-exit tea moisture content, and fuel consumption are maintained at optimal states during the course of the drying of tea. The additional aim of this system is to balance the cost of production and the quality of the final product. Using the Guggenheim-Anderson-De Boer (GAB) model, the optimum drying temperature was found to be 100-110°C, while maintaining a dryer-exit tea moisture content of 3 to 3.12 per cent, at a drying rate of 3 per cent per minute. A Barix control application to control the system’s activities, using the web user interface (WUI), was also developed.