http://ir.mu.ac.ke:8080/jspui/handle/123456789/61 2026-07-21T01:21:23Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10358 Modification of automobile shock absorbers thickness and weight parameters for adaptation on poorly maintained roads via mathematical modelling Owino, Benard Ouma; Kweyu, Cleophas M.; Rotich, Titus Chebion Uneven oscillatory forces applied to an object cause vibration, which can lead to noise, discomfort, and mechanical wear. The optimization of shock absorber thickness and weight is critical for enhancing vehicle performance on poorly maintained roads. In automobiles, vibrations due to irregular road surfaces have been mitigated using shock absorbers to enhance performance, comfort, and control. The main aim of this study was to determine the effect of automotive weights and shock absorber thickness on automobile vibrations. The objectives of this study were; to formulate a mathematical model describing the effect of automobile weight on unsteady vibrations; to generate numerical solutions of the mathematical model equations for the shock absorber modified to reduce vibrations at the mounting points; and to analyze from the numerical solution the effects of increase in velocity and weight on the automobile unsteady spring vibration. A mathematical model was developed, utilizing the central difference scheme for discretization and solved using the Jacobian iterative method, with stability conditions implemented. Through computational simulations, various thickness and weight configurations were tested under diverse road conditions. The results indicate a significant improvement in shock absorber performance, with optimized configurations that increasing shock absorber thickness reduced vibration amplitude by approximately 35%, while increased vehicle weight amplified vibrations by 20%, necessitating thicker shock absorbers for stability. Higher speeds above 80 km/h intensified unsteady vibrations on poorly maintained roads. The study concludes that modifying shock absorber thickness and optimizing weight distribution can effectively minimize automobile vibrations. 2026-02-01T00:00:00Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10353 Techno-economic analysis of local manufacturing of perovskite photovoltaic modules for electricity generation in Ethiopia Meheretu, Getnet; Worku, Ababay Ketema; Yihunie, Moges T.; Koech, Richard K; Wubetu, Getasew A Perovskite solar cells can be potential contenders for future photovoltaic technologies due to their high efficiency, affordability, and simple manufacturing process. This study focuses on the techno-economic analysis of local manufacturing of perovskite solar panels in Ethiopia. The total manufacturing costs were found to be $0.29 /wp or $/69.6/m2. The Minimum Sustainable Price was calculated to be $0.38 /wp or $91.2/m2. Using a Monte Carlo simulation, the techno-economic metrics such as Net Present Value, Pay Back Period, Rate of Return, Profitability Index, and Levelized Cost of Energy were evaluated to determine project viability. The analysis showed a positive Net Present Value, a Payback Period of 7 to 8 years, an Internal Rate of Return of about 12 % with its average rate of return greater than the weighted average cost of capital, and a profitability index of 1.22, indicating project viability. The levelized cost of energy was estimated to be $0.019/kWh, which is lower than the selling price of electricity by the Ethiopian electric power authority, suggesting economic viability. 2025-10-01T00:00:00Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10348 Enhancing stability and efficiency in perovskite solar cells: insights into inorganic HTL deposition and interface defect passivation Amune, Daniel I.; Koech, Richard; Dahiru, Muhammad Sanni; Botsoa, J.; Anye, Vitalis Chioh; Fidel, W. The perovskite solar cell (PSC) as an emerging and promising type of solar cell has been extensively studied, but instability is still a major challenge. Replacing the hygroscopic organic hole transport layer (HTL) in PSCs can result in an improvement in the device stability. However, it is still difficult to deposit inorganic HTLs onto the underlying perovskite layer without eroding or distorting it in the regular n–i–p architecture, thereby inducing defects at the interface and reducing the performance of the device. In this study, the performance of PSCs with an inorganic HTL is modelled using SCAPS-1D. The perovskite-HTL interface defect density was varied from 1.0 × 1012 to 1.0 × 1020 cm−3. We realized that, for PSCs based on some hole transport materials (HTMs), the effect of interface defect density was not significant. We observed that the HTL/perovskite valence band offset (VBO) plays a significant role in the phenomenon observed. In particular, a zero or slightly positive VBO results in an increase in both the defect tolerance and device efficiency. This information provides insights into the fabrication of PSCs with improved interface defect passivation and also enables the fabrication of perovskite solar cells based on physically deposited inorganic charge transport materials. 2026-03-01T00:00:00Z http://ir.mu.ac.ke:8080/jspui/handle/123456789/10343 Mathematical modeling of the amplitude dynamics of saturated sludge in a landslide wave surge Karugutiang, David Pkiach; Kweyu, Cleophas; Kaneba, Christopher Mathematical model is formulated using Partial differential equations, and analyzed to describe the dynamics of wave propagation with application to landslide. Its occurrence leads to loss of lives of people and their properties. This study aims at understanding the dynamics of landslide wave propagation, in order to make adequate projection in an attempt to mitigate the risks involved in the occurrence. The objective of this study is; to develop a mathematical model to describe the dynamics of a landslide wave propagation. Numerical solutions were carried out using Runge-Kutta algorithm’s inbuilt in MATLAB, to simulate the current and future dynamics of the model. The mathematical model was used to simulate and analyze landslide wave propagation phenomena in affected areas. The results of this study showed that the maximum amplitude of 0.49m is achieved at an inclination of 50° and gradually drops down to 0.45m at a slope of 19.2°. This defines the region where inhabitants should be relocated to avoid loss of lives and destruction of property during the occurrence of landslide. The high amplitude occurs in the wave propagation region, necessitating the implementation of control strategies along the same region. 2026-04-01T00:00:00Z