University of Dar es Salaam Research Repository

Welcome to Online Research Repository of University of Dar es Salaam (UDSM).

The Research Repository of University of Dar es Salaam (UDSM) is the online/digital collection of research and publications from University of Dar es Salaam. The Research Repository UDSM collects preserves and makes available publications and conference papers, journals, books and other outputs created by UDSM researchers. Researchers can upload their CV while simultaneously updating their profiles. Participation in UDSM Research Repository helps to ensure that publications are more visible and highly cited.

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Recent Submissions

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Overview of optimal operations of renewable energy power systems in microgrid and virtual power plants
(Elsevier, 2023-11-23) Mushi, Aviti Thadei; Mnkeni, Godwin Elinazi; Justo, Jackson John; Mwasilu, Francis Avilus; Mwinyiwiwa, Bakari Mohamedi Mfaume
Renewable energy sources (RES) in microgrids and virtual power plants are considered to be the backbone of these power systems. The RESs have been shown recently to reduce the costs per kWh by 85% in South Africa, some viability to electrify airport in Tanzania [1,2], and rural villages [2 4] Some reported case studies show that investing in the same project five years later has a great impact on running costs [5] and can improve electrification rates as some other technologies can [6 8]. The RESs in microgrid configuration are considered to be the most costeffective power solutions to meet the load requirements of people that live in rural areas [9,10].
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Overview of Renewable Energy Power System Dynamics
(Elsevier, 2023-11-23) Mushi, Aviti Thadei; Suwi, Owdean; Justo, Jackson John
Depletion of fossil fuel, global warming, and environmental pollution clarify the importance of renewable energy sources (RESs). Renewable energy is derived from the Earth’s natural resources that are not finite or exhaustible, especially during human lifetime. Renewable resources include biomass energy (such as ethanol), microbial fuel cell [1], hydropower, geothermal power, wind energy, and solar energy [2]. Offline solar photovoltaic (PV) can power rural villages [3 5], or airports [6] at an equitable levelized cost of energy (LCOE) if the wind is not enough to give economies of scale [7 9].
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MPPT DC-DC Buck-Boost Converter for Off Grid Hybrid Solar-Wind-Battery System in Ikuza Island, Tanzania
(Tanzania Journal of Engineering and Technology (TJET), 2023-11-14) Nassoro, Nassoro Sadick; Msigwa, Consalva Joseph; Mushi, Aviti Thadei; Mwinyiwiwa, Bakari M.M.
Ikuza Island in Kagera-Tanzania faces lack of electricity due to cost challenges of extending the grid by marine cables and other transmission facilities. These makes such endeavour not appealing to the supply authority due to those higher charges. Therefore, this paper undertakes to design hybrid renewable energy sources for the island by specifically focusing on the buck-boost converter for the energy conversion from these renewable resources. The design of the bidirectional buck-boost converter for maximum power point tracking in off-grid hybrid renewable energy systems is multifaceted due to the inhomogeneity nature of the renewable energy sources. The bidirectional buck-boost converter, solar PV, wind-based generator, and energy storage system are designed and simulated in MATLAB/Simulink software. The designed system is tested with varying solar irradiance (750 to 1000 W/m2), temperature (20 to 25C) and wind speed (150 to 157.5 radians/s) at constant load of 260 A while load variation involved varying the load current from 0 to 260 A at solar irradiance, temperature, and wind speed of 1000 W/m2, 25 C and 157.5 radians/s, respectively. The variation of DC link bus voltage at different load conditions is reported. The simulation results show that the designed converter is able to maintain DC link voltage at 600 V. Moreover, the DC link voltage shows a maximum drop of approximately 0.67% during the constant load condition. Contrarily, a significant improvement is observed when the designed converter operates with the hybrid system of solar PV, PMSG-based wind generator and with energy storage system.
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Developing a Laptop Power Adaptor for 12 V and 24 V Solar PV Source
(IEEE, 2023-05-22) Chilumba, Lulu; Mushi, Aviti Thadei; Mwinyiwiwa, Bakari M.M.
Rural and urban areas of developing countries such as Tanzania suffer from lack of reliable electricity supply. This situation limits the usage of portable electronic gadgets such as laptops, and mobile phones. This paper designs and simulates a laptop charger adapter using a DC-DC single ended primary inductor converter (SEPIC). This charging adapter accepts two voltage levels of varying sources of solar photovoltaic (PV) power. Its output is constant DC at 19.5 V and maximum 100 W power while input is either the variable 12 V or 24 V solar PV power source. The maximum power point (MPPT) algorithm is integrated with proportional integral (PI) controller to achieve the desired output. This design was validated numerically using the MATLAB/Simulink environment. Several results are presented showing the performance with the cases of varying solar irradiation from 800 W/m 2 to 1000 W/m 2 or vice versa. These simulation results indicate possibility of future work of the viability to fabricate the adaptor and test it in laboratory and in field.
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Digitalization of Tanzania Health Care Services: Telemedicine Infrastructures to Link Rural and Urban Areas
(MUST Journal of Research and Development, 2023-08-10) Mushi, Aviti Thadei; Justo, Jackson John; Katemi, Richard Jackson; Wikedzi, Alphonce Wendelin; Bitebo, Ally Tahir; Mwakijale, Joseph Sisala; Chibwana, Fred Demetrius; Katandukila, Jestina Venance; Budeba, Mussa Daniel
The majority of people in Tanzania live in rural areas where decent medical care is still a challenge. Consultation with specialists located in cities where hospitals with modern facilities exist becomes impossible for patients living in the rural areas of Tanzania. Patients travel long distances from remote areas to cities and make appointments to see the specialist, for which they incur several costs, including accommodation and subsistence. These can be addressed using Information and Communication Technology (ICT) and mobile phones. However, developing an infrastructure for a platform for bringing specialists or a panel of specialists living in cities to offer consultation services to patients living in rural areas has remained a challenge. This research, therefore, is aimed at improving health care services for rural patients by developing telemedicine technology in the context of Tanzania. This will ensure that patients have access to the specialists as quickly as possible instead of travelling long distances to the cities and spending time and money waiting for appointments. With the proposed system, collection and delivery of samples and drugs using drone technology, real-time online consultation with remote specialist doctors, and telesurgery will be possible. This telemedicine platform has been developed and tested. Patients could register, and doctors could prescribe tests and medicine within the system. Both video and audio calls were possible. Payments using the NHIF cards were demonstrated. The drone carried dummy samples from Magufuli Hostels to the UDSM Health Centre in Dar es Salaam. Further improvements could be made by testing the system with a much larger population over longer distances.