Browsing by Author "Chepkwony, Isaac"

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    Investigating the Impact of TB or COVID-19 Infections on a Population Suffering from TB/COVID-19 Coinfection
    (Asian Journal of Probability and Statistics, 2024) Githinji, Mary Ng’endo; Chepkwony, Isaac
    The discovery that the spread of tuberculosis reduced significantly in the last two years has been associated with the preventive measures placed to combat the spread of COVID-19. This shows a string correlation between the spread of COVID-19 and tuberculosis in any population. It is worth noting that tuberculosis and COVID-19 are among the leading most deadly diseases in the world today. The correlation in their spread also leaves us to believe that the spread of one can enhance the spread of the other. Hence, we propose the situation where a population is co-infected with the two diseases. The mathematical model is formulated using conservative laws and the resulting model analysed. The stability of the co-infection is analysed and the non-negativity conditions for the solution is established. It is found that tuberculosis sub-population reaches the highest capacity when the recruitment into the COVID-19 subpopulation is the lowest while the COVID 19 sub-population is attained when the rate of recruitment into the COVID-19 subpopulation is the highest.
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    A Mathematical Model of Rabies Transmission Dynamics in Dogs Incorporating Public Health Education as a Control Strategy -A Case Study of Makueni County
    (Sciencedomain International, 2020) Musaili, Jane S.; Chepkwony, Isaac
    Rabies is a zoonotic viral disease that affects all mammals including human beings. Dogs are responsible for 99% of human rabies cases and the disease is always fatal once the symptoms appear. In Kenya the disease is still endemic despite the fact that there are efficient vaccines for controlling the disease. In this project, we developed SIRS mathematical model using a system of ordinary differential equations from the model to study the transmission dynamics of rabies virus in dogs using public health education as a control strategy. The reproduction number R0 was calculated using the Next Generation Matrix. Both disease free and endemics equilibrium points were determined and their stability analysis performed. From the stability analysis results it was found out that the disease free equilibrium point is both locally and globally asymptotically stable when R0 < 1 and the endemic equilibrium point is both locally and globally asymptotically stable when R0 > 1. Numerical simulations done using Matlab indicated that education of the public on administration of both pre and post exposure vaccines to dogs and responsible dog ownership
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    Thermal Applications of Carbon Nanotubes in Polyethylene Glycol in the Presence of Magnetic Field on Electronic Devices
    (IOSR Journal of Mathematics (IOSR-JM), 2025-04) Muteti, Winfred; Chepkwony, Isaac
    Background: In this study, the thermal management of electronic devices, specifically CPUs, using carbon nanotubes (CNT) dispersed in polyethylene glycol (PEG-400) under the influence of a magnetic field was studied. The research aims to optimize cooling performance by enhancing efficiency, extending the operating temperature range, and improving the reliability of such systems. Materials and Methods: The study modeled impingement cooling using a Darcy-Brinkman-Forchheimer approach and considered the effects of viscous dissipation. The governing nonlinear partial differential equations were converted into nonlinear ordinary differential equations (ODEs) by utilizing similarity variables and solved using numerical methods. CNT-PEG-400 nanofluid flowing via a porous metal foam CPU cooler with a fan and a heated CPU surface was simulated. Results: The investigation of key parameters like Hartmann number, Reynolds number, Darcy number, and porosity revealed that increasing the Darcy number significantly enhances heat transfer. The Hartmann number’s effect varies with porosity, where stronger magnetic fields are advantageous for highly porous metal foams, ultimately improving cooling efficiency. Conclusion: CNTs increase both the density and viscosity of PEG-400, leading to enhanced heat transfer characteristics, which improve overall cooling performance. These findings contribute to optimizing cooling strategies for CPUs and other electronic devices, especially when using CNT-PEG-400 nanofluids in the presence of magnetic fields.