Engineering
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- ItemDesign of Yb3+ doped laser for industrial application.(The University of Zambia, 2021) Simpungwe, MosesThe design and development of ytterbium-doped fibre lasers (YDFLs) operating around 1018nm laser wavelength and pumped around 976nm has advanced in technology since the first ytterbium laser was tested in 1988. The fiber lasers are used in various sectors such as communications, material processing, medical to mention but a few. Laser designers have the great objective of ensuring that the parameters such as pump power, active fibre cable and ion concentration are optimized for better quality laser output power. Further, the right choice of the output coupling between the Dichroic mirror (DM) and Fibre Bragg Grating (FBG) help eradicate the challenges faced in laser device design in terms of power output. Previous studies have reported use of diode lasers operating around 976nm as pump sources and lasing around 1018nm. There are, however, few reports on pump source use of 980nm on ytterbium doped laser fibre in the literature. This study therefore sought to contribute to improving on the power output of the YDFLs operating in continuous wave (CW) mode. In this modeling, a 980nm wavelength pump source with a lasing value at 1018nm wavelength and Dichroic couplers are deployed. In modeling the Yb3+ doped Laser, a quantitative approach was used. Linear differential equations were solved in order to determine the optimized values for the variables. Simulations using Computer software simulation -MATLAB were conducted. Power output of 59.64W was achieved against pump power of 68W, giving a slope efficiency of 87.71%. The operational characteristics of this Yb3+ doped fiber laser device in bidirectional pumping promises significant applications in radar, laser machining, free space communication and medical treatment. The results, further, show that the fiber cable length, the ion concentration and the choice of reflectivity on the OC and HR are critical when designing a fiber laser. Based on the results from the model, this study recommends that a study of the model be conducted experimentally to ascertain if the theoretical results will match with the experimental results.
- ItemCapability of Zambian industries to manufacture grid-scale wind turbine blades and towers.(The University of Zambia, 2020) Banda, AmosThe Zambian electricity grid system has been dominated by hydropower at 96 %, 2.1 % thermal and 1.7 % renewable (Kaluminiana, n.d.). During the 2014 - 2015 rainy season, Zambia received very low rains which led to reduced electricity production at the two major power plants. In the light of this situation, there was a push towards diversification in the power generation mix to achieve a more resilient energy system. This quest for diversification has led to the inception of grid-scale wind power feasibility studies at ten sites distributed around the country. These feasibility studies were aimed at establishing the availability of the wind resource for grid-scale power generation. This will lead to the development of the wind power industry in Zambia. However, these studies did not investigate the capability of local support industries, this research intends to bridge that knowledge gap. The purpose of this study was to investigate and profile the capability of Zambian industries to manufacture wind turbine (WT) blades and towers. The study used a mixed-method approach to collect data, both qualitative and quantitative approaches were employed in a complementary manner. The population of Zambian industries was collected from the Zambia Association of Manufacturers (ZAM) based on the 2018 registered members. This data was used to define the population for the study. The population was arranged in three strata whose characteristics are homogeneous within each stratum. Due to the low population, the study was conducted on the whole population. The quantitative data was collected from each stratum using a quantitative data collection tool developed for each stratum and analysed. A review of the wind resource assessment projects has demonstrated that there are Class III and Class IV sites in certain parts of Zambia. The results from this study have revealed that on an as-is basis there are no companies in Zambia which can manufacture WT blades and towers.
- ItemInformation and knowledge sharing using information communication technology (ICT) application amongst small scale farmers in Lusaka province of Zambia.(The University of Zambia., 2019) Shawa, CatherineEvolution of Information Communication Technology (ICT) has led to various tools and methods being developed enabling communities and individuals to create online social networks known as Social Media platforms. Online social networks are platforms for sharing information and knowledge in real time. The main objective of the study was to evaluate current Social Network platforms being accessed by Small Scale Farmers in Lusaka Province of Zambia and develop an integrating small scale farmers’ information and knowledge into a single online support system. The research study design was qualitative, quantitative method and empirical study was conducted using questionnaires. The target population was 46,000 of which a sample size of 397 (at 95% confidence level) was calculated using Epinfo start calc. Stratified sampling method was applied. Statistical analysis was performed using SPSS and Excel. Inclusive, are views from Small Scale farmers’ partners. In this study 91% of people who took part were successful respondents. Using detailed literature review, questionnaire and structured interviews, the study deduced that 97% of small scale farmers searched for information using ICT applications. Of the successful respondents, 51% cited none availability of required searched information. Notably, 61% of information available was believed not to be authentic. However, only 52% of respondent who believe information not being authentic said they required expert advice on available information. Incidentally, 84% of respondents agreed to the idea of having a single integrated information support system.. The study yielded that farmers face various challenges including inadequate information, difficulty in accessing information, none availability of searched material, lack of authenticity and lack of expert advice respectively. The study recommends that deliberate Agriculture ICT policy be in place on small scale farmers’ information. Through this, implementation of single online support system with expert presence be effected. This will lead farmers to access different agricultural information needs.
- ItemEnhanced local contractor participation in the Zambian water supply and sanitation sub-sector.(The University of Zambia., 2024) Katotobwe, Chanda A.B.Water supply and sanitation (WSS) construction projects involve the construction of specialized infrastructure such as water treatment plants, pumping stations, pipelines, reservoirs, and sewage treatment facilities. These type of construction projects present unique technical, regulatory, and societal challenges, often executed by foreign contractors in developing countries like Zambia, with limited local participation. This disparity sparks debates on dependency and sustainability. Existing theories insufficiently address this issue. The overarching research inquiry investigates the dynamics surrounding the low dominance of local contractors in executing WSS projects in Zambia. Additionally, the study delves into the primary barriers confronting local contractor participation in Zambia as they compete for and secure contracts within WSS projects. Employing a Straussian Grounded Theory methodology, the study developed thick descriptors for the underlying issues explaining local contractor participation (LCP) in the WSS sector, which led to the development of theory and a framework advocating for enhanced LCP. Initially, a variety of emerging issue clusters and their corresponding phenomena were delineated and categorized into thematic descriptors. These encompassed clusters relating to procurement and taxation, funding sources, constraints on plant and equipment resources, specialized financial support, contractor technical capacity, governmental capacity building efforts, and regulatory enforcement. Based on these identified issue categories and their observed phenomena, an LCP theory was introduced as a primary contribution of the study within the theoretical proposition framework. This theory encapsulated the theoretical propositions and strategies advocating for enhanced LCP. It posited that a comprehensive approach, tax incentives, affirmative procurement actions, and specialized financial support, could significantly enhance the involvement and competitiveness of local contractors, particularly in the construction industry, specifically within the WSS sector. Tax incentives and leniency policies reduce financial burdens on local contractors, allowing for reinvestment in business growth and improved financial stability. Simultaneously, affirmative actions in procurement ensure equitable competition, levelling the playing field against larger foreign competitors and addressing inherent disadvantages. Furthermore, integrating specialized financial support tailored to the unique needs of local contractors within the sector addresses financial barriers and facilitates their participation in projects. Following the consequential phenomena and strategies upon which these theories were based, holistic strategies and reforms associated with these three theoretical propositions included: revamping taxation policies and procurement practices; diversifying funding sources for sustainable growth; creating equitable opportunities through procurement strategies; establishing specialized financial support institutions; establishing specialized financial support institutions; strengthening policy frameworks and enforcement mechanisms; bridging the knowledge gap for local contractors; mitigating political interference for fair competition; and enhancing government capacity building initiatives. The study advocates for policy, legal and institutional restructuring based on this theory to enhance local contractor participation in WSS projects in Zambia and other developing countries.
- ItemStudy on compressive, tensile and bond properties of used tire rubber reinforced concrete.(The University of Zambia, 2021) Bwalya, TheresaConcrete is one of the most widely used construction material in the world and the construction industry is looking for ways of making concrete using greener methods so as to reduce ecological effects on the environment that come as a result of large scale exploitation of natural aggregates. The construction industry is also in need of finding cost-effective materials to enhance the properties of concrete. Cement and aggregate, which are the major constituents in concrete production are the vital materials needed in the construction industry. This has inevitably led to a continuous and increasing exploitation of natural materials to produce the constituents for concrete production. The result has been the depletion of virgin raw materials and increased effects of environmental degradation. Parallel to the need for the utilization of the natural resources emerges a growing demand to protect the environment and preserve natural resources such as the aggregates and stone for cement production, by use of alternative materials such as recycled or waste materials. In this research, a study was carried out on the use of recycled rubber tyres as a partial replacement for coarse aggregates in concrete production. Recycled waste tyre rubber is a promising material in the construction industry due to its reduced weight, elasticity, energy absorption, sound and heat insulating properties. However, literature suggests that there is a significant loss in the strength of rubberized concrete with increasing tyre content. Further, workability and bond properties have been reported to reduce as well. Therefore, it is necessary to lower or control this loss of strength and other parameters in concrete in the replacement process of natural aggregates. This research aimed at studying the compressive, tensile and bond properties of used tyre rubber reinforced concrete. The research also aimed at establishing whether the use of rubber reinforced concrete (rubberized concrete) is technically and economically viable in Zambia. Rubber modified concrete was compared to normal concrete produced from natural coarse aggregates and Portland cement. The research involved literature review, laboratory testing on natural raw materials and used rubber as aggregates (to determine their properties and suitability for use in concrete), concrete mix design, concrete trial mixes, and tests on both wet and hardened concrete. Test results from laboratory experiments enabled determination of mechanical, physical and durability properties, as well as establishment of the extent of substitution of normal aggregates with waste rubber as aggregate in concrete production. Three classes of concrete, C15, C20 and C25 were produced by substitution of selected percentages of aggrgates by treated chopped waste tire rubber. The chopped rubber, whose surfaces were first roughened by use a wire brush, was later soaked in clean water and then left to dry completely in the sun. This was done to increase the inter-phase bonding between the rubber particles and cement. The percentage replacement of coarse aggregates was 5, 15 and 25 per cent. The size of the chopped rubber aggregates varied from 20 mm to 19 mm. Slump, permeability and bulk density tests were conducted on fresh concrete mixes for both the normal and treated rubber modified concrete. Similarly, compressive strength, tensile splitting strength, bond test and durability against acid attack tests were conducted on hardened concrete. The research established that rubber modified concrete compares favourably with standard concrete, with up to 15 per cent replacement of coarse aggregate. At 15 per cent replacement, only 0.1 per cent loss of strength was established. There was observed reduction in properties with 25 per cent replacement. Rubber modified concrete performed better by gradual cracking at elevated temperatures. There is potential for rubber modified concrete products in Zambia which in turn mitigates adverse impacts resulting from over exploitation of natural aggregates and disposal of used rubber tires.