School of Engineering (SEng.) Collections

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    Design, simulation, and Financial Analysis of a Hybrid Solar PV - Biogas system for Dairy Farms in Uganda case study: Mutanoga Dairy Farm.
    (Makerere University, 2026) Mukabaikaliza, Mukwenda Rosemary
    Lack of reliable electricity, rising energy costs, insufficient waste management and over dependence on firewood for milk pasteurization and cooking has led to environmental issues such as pollution, health issues and deforestation. Therefore, this study aimed to design, simulate and conduct the financial analysis of a hybrid solar PV-biogas energy system for Mutanoga diary farm as an alternative source of energy to meet the demands of the farm. The objectives were to determine the energy profile and energy resources of the dairy farm, to determine the appropriate size of the hybrid solar-biogas energy system components to meet the energy demand of the dairy farm and to conduct the financial analysis of the solar-biogas hybrid system to evaluate its feasibility. The solar GIS software and the solar radiation meter were used to determine the solar resource data. Cow dung used in the biodigester to produce energy is collected by a group of workers and transported from the farm using donkeys. HOMER software was used to perform technical and financial analysis. The energy demand of the farm was 278.404kWh/day with a peak load of 14.55 kW, yearly average global horizontal irradiation of 5.145 kWh/m2 per day. The designed hybrid energy system comprised of 53.374 kW PV modules, a 10 kW biogas generator, battery storage with capacity of 5,043.78 Ah, and a 11.2 kW sized Inverter. The hybrid energy system generated annual electricity of 117,352kWh/year producing excess electricity of 15,735kWh/yr equivalent to 15.5%. The levelized cost of energy (LCOE) of 403 Ushs/kWh and a total net present cost (NPC) of Ushs 488,002,900. The LCOE is about 1.62 and 1.196 times lower than the average electricity end-user tariffs for households and commercial consumers in Uganda. With a lifespan of 25 years, the return on investment (ROI), internal rate of return (IRR), simple and discounted payback period (PBP) of this renewable energy project is estimated at 62.8%, 29.7%, 7.09 years, and 7.09 years, respectively. This research has provided an insight that the hybrid solar PV-biogas system is a valuable investment for dairy farms aiming to reduce their operating costs while ensuring a stable energy supply. Its adoption could play a vital role in advancing sustainable agriculture for dairy farms and fostering renewable energy transitions in rural communities. However, there is a need for further studies to be done on the comprehensive Life Cycle Assessment (LCA) of the hybrid energy system to evaluate its full environmental impact.
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    Key factors for the current state of occupational safety, health, and environment management in the cement manufacturing industry
    (Springer Nature, 2025-12-09) Ssemuddu, Jeffy Briton ; Olupot, Peter Wilberforce ; Kirabira, John Baptist ; Okure, Mackay
    Despite the inherently high-risk nature of cement manufacturing, the performance of Occupational Safety, Health, and Environment (OSHE) remains suboptimal, particularly in developing countries. This study investigated the key determinants influencing safety management in two Ugandan cement production facilities using a quantitative research design. Perception-based survey data were collected from 223 participants in Plant A and 186 participants in Plants B and analyzed at univariate, bivariate, and multivariate levels using IBM SPSS Statistics (Version 2020). The results revealed that in Plant A, the presence of a dedicated OSHE budget significantly influenced safety performance (p < 0.005), while in Plant B, the existence of a formal safety policy and specialized worker training were critical determinants (p < 0.05). Across both plants, active worker participation in OSHE programs and heightened hazard awareness consistently emerged as pivotal factors shaping the current state of safety management in the cement industry. These findings highlight the importance of targeted investment in reward systems, recognition mechanisms, continuous education, training, and accountability frameworks to enhance safety outcomes. The study recommends that stakeholders in Sub-Saharan Africa’s cement industry adopt proactive and performance-driven OSHE strategies. These should include embedding OSHE metrics into labor contracts and appraisal systems to improve compliance, accountability, and overall industrial competitiveness. The findings contribute directly to the advancement of Sustainable Development Goals (SDGs) 3, 8, and 9, supporting health and well-being, decent work, inclusive economic growth, and sustainable industrial innovation.
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    Advancing safety and sustainability through occupational safety, health, and environment integration in Uganda’s cement manufacturing industry
    (Makerere University, 2026) Ssemuddu, Jeffy Briton
    Cement manufacturing poses significant risks due to inadequate Occupational Safety, Health, and Environment (OSHE) performance, a challenge that remains insufficiently examined despite the industry’s rapid expansion. This study, therefore, aimed to evaluate OSHE management practices, assess workplace risks, analyze the integration of safety management, and the mediating effect of production pressure on safety performance across two major cement plants. A mixed methods approach was employed. For objective (i), perception surveys involving 233 participants in Plant A and 186 in Plant B were analyzed using SPSS 2020, while hazard checklists and site inspections engaged over 400 respondents. Risk assessment tools, including a 6×6 risk assessment matrix and risk modeling algorithms such as Artificial Neural Fuzzy Interface Systems (ANFIS), and Structural Equation Modeling (SEM) using AMOS, were applied to strengthen analysis and prediction. The results revealed that an OSHE budget was critical in Plant A, whereas OSHE policy and specialized training were essential in Plant B (p < 0.05). In both plants, worker involvement and hazard awareness were key drivers of safety management, highlighting the need for rewards, recognition, education, training, and accountability programs. Hazard assessments identified confined spaces, unsafe behaviors, and mechanical and electrical hazards as major threats, with baseline risk ratings exceeding 30/36. ANFIS models predicted escalation under production pressure and during irregular shifts, underscoring the need for dynamic risk assessment, predictive tools, and advanced Personal Protective Equipment. Further analysis demonstrated a strong positive correlation between safety integration and safety performance, with Labor Safety Accountability (LSA) and Management Safety Accountability (MSA) exerting the most significant influence (p < 0.001). Contractor Safety Management (CSM) and Safety-Based Labor Management (SBLM) also made substantial contributions. However, Structural Equation Modelling (SEM) revealed that production pressure manifested through Production Pressure Intensity, Disruptions in Safety Protocols, and Normalization of Unsafe Practices, negatively mediated the safety integration-performance relationship, with Production Pressure Intensity (p = 0.014) and Disruptions in Safety Protocols (p = 0.026) significantly reducing safety outcomes. Overall, the study confirms that safety integration enhances safety performance, but its benefits are undermined by production pressure. These findings underscore the need for proactive, data-driven OSHE strategies to improve worker safety in Uganda’s cement industry.
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    Performance analysis of an aerial assisted cellular network
    (Makerere University, 2026) Mugala, Sheila Ndoboli
    An Aerial Assisted Cellular Network (AACN) using Unmanned Aerial Vehicles (UAVs) as Aerial Base Stations (ABSs) is envisioned as a cost-effective way to provide network connectivity especially in rural and remote areas. Performance analysis of AACNs often considers dense deployment of ABSs, ignores low power ground BSs and does not quantify the effect of ABSs on ground BSs. Additionally, interference mitigation for AACNs deserves attention because of the strong LineOf-Sight (LoS) links from the ABSs. This thesis, therefore, formulated a downlink analytical model for the coverage probability, average rate and energy efficiency of an AACN. It also compared the performance of three Joint Transmission Coordinated Multipoint (JT CoMP) schemes and Dynamic Point Selection (DPS) for interference mitigation. Since ABSs are size, weight and power limited, it was imperative to investigate low complexity Coordinated Scheduling/Coordinated Beamforming (CS/CB) techniques for a multi-antenna system under imperfect channel state conditions. An analytical model based on Poisson Point Processes (PPPs) and Monte Carlo (MC) simulations were used to establish the performance of an AACN with low density of ABSs in a rural environment. The analytical results were closely matched by the simulation results hence validating the analytical model. Both results show that the coverage probability initially increases with ABS altitude due to increasing probability of LoS, reaches an optimum and then drops due to the high path loss. At a Signal-to-Interference Ratio (SIR) threshold of -15 dB and UAV density of 2 / km2 , the optimum ABS altitude is 100 m which gives a coverage probability of 0.97. However, at 100 m, the optimum density is 5 / km2 with coverage probability of 0.98. The simulation results show that interference aware JT CoMP gives the best performance compared with fixed number and fixed region. It inherently chooses the strongest interferers and includes them in the cluster. Three low complexity CS/CB techniques with proportional fair scheduling are compared. Block diagonalisation using Householder transformation (BD HH) gives the lowest overall complexity and strong resilience to CSI error. Therefore, it is the most pragmatic beamforming technique for an AACN. Through performance analysis for an AACN, performance bounds are established and inherent trade offs revealed. The results will contribute to the establishment of UAV operational parameters developed by UAV manufacturers, network operators, network regulators and airspace regulators to ensure their safe and efficient integration into cellular networks. Keywords: Aerial Base Stations, Block Diagonalisation, Coordinated Multipoint, Coverage Probability, Unmanned Aerial Vehicles
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    Structural Equation Modeling of Safety Integration and Production Pressure Effects On Safety Performance in Cement Manufacturing
    (Scientific Reports, 2026) 1. Jeffy Briton Ssemuddu, 2. Derrick Kajjoba, 3. Peter Wilberforce Olupot, 4. John Baptist Kirabira, 5. Mackay Okure,
    The cement industry continues to experience substantial production pressure driven by steadily increasing global demand. In this context, the present study investigates the relationship between safety integration and safety performance, with production pressure examined as a mediating variable. Structural Equation Modelling (SEM) was employed to analyze these relationships within the cement industry. Safety Integration included Labor Safety Accountability, Management Safety Accountability, and Contractor Safety Management, while Safety Performance was categorized into incident measurements (SPx), management actions (SPy), and continuous improvement efforts (SPz). Production pressure encompassed the Normalization of Unsafe Practices, Disruptions in Safety Protocols, and Production Pressure Intensity. Data from 238 participants, collected over 3 months were analyzed using SPSS and AMOS (version 23). Labor Safety Accountability consistently influenced safety performance (p<0.001 on SPx, p<0.001 on SPy, p=0.001 on SPz), while Contractor Safety Management and Management Safety Accountability also showed significant effects (p=0.011 on SPx, p<0.001 on SPz). Production Pressure Intensity and Disruptions in Safety Protocols negatively affected safety performance (p=0.014 on SPx, p=0.026 on SPy) respectively, while Normalization of Unsafe Practices exhibited a weak influence. The findings confirm that safety integration significantly enhances safety performance, whereas production pressure exerts a substantial negative impact, diminishing overall safety outcomes in the cement industry. Unlike prior studies that largely examine safety performance in isolation, this research uniquely demonstrates how production pressure mediates the link between safety integration and safety outcomes in the cement industry, highlighting the dual challenge of maintaining productivity while safeguarding workers and offering new insights for both scholars and practitioners in high demand industrial sectors.