Department of Physics

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Development and validation of an anti-leakage least-squares spectral analysis-based zenith tropospheric delay model for the East African region.
(Busitema University, 2026) Matsukuni, Nicholas
Accurate estimation of Zenith Tropospheric Delay (ZTD) remains challenging over East Africa because of strong spatial and seasonal atmospheric variability and the limited distribution of continuous GNSS observations. Existing empirical models such as GPT3 and GTrop mainly describe temporal ZTD variability using predefined harmonic terms, which may not adequately represent the more complex regional seasonal behaviour. This study developed a regional ZTD model for East Africa using Anti-Leakage Least-Squares Spectral Analysis (ALLSSA) and ERA5 reanalysis data from 2013 to 2020. Unlike fixed-harmonic approaches, the developed model represents temporal ZTD variability using statistically significant frequencies identified adaptively from the time series, allowing the spectral structure to respond to regional differences in atmospheric behaviour. ERA5 atmospheric profiles were used to derive ZTD, while the vertical dependence was represented using a reference ZTD and a height-dependent decay parameter. Sensitivity analysis showed that increasing the number of ALLSSA iterations beyond N=40 produced little further reduction in RMSE, and this value was adopted for model development. Internal evaluation against ERA5-derived ZTD yielded a mean correlation coefficient of 0.99 and a mean RMSE of 25.19 mm, showing that the model retained the dominant variability represented in ERA5. Independent validation using GNSS-derived ZTD from the Nevada Geodetic Laboratory at nine stations in Uganda, Kenya, and Tanzania gave a mean RMSE of 21.99 mm and a mean bias of -5.30 mm. Compared with GTrop and GPT3, ALLSSA reduced the mean RMSE by approximately 29-32% and the absolute mean bias by approximately 48-62%. The improvement was not uniform across the region. It was greatest in the equatorial sub-region, where ZTD exhibits a bimodal seasonal cycle, and became smaller farther south where the temporal behaviour is predominantly annual. Seasonal bias showed a less consistent pattern, with GPT3 or GTrop producing smaller absolute biases under some conditions despite their larger RMSE. The results show that allowing the temporal representation of ZTD to adapt to the frequencies present in the regional signal provides an advantage over fixed-harmonic empirical models, particularly where seasonal atmospheric variability is more complex. The developed approach therefore provides a basis for improved regional ZTD estimation over East Africa.
Design and construction of a simple battery level indicator.
(Busitema University, 2026) Kirya, Dauson
This study focused on the design and construction of a simple and low-cost battery level indicator using locally available electronic components. The study was carried out because many users of battery-powered devices cannot easily determine the remaining battery charge level before complete discharge, leading to sudden power failure and reduced battery lifespan. The project therefore aimed at developing an affordable and reliable battery monitoring device. The battery level indicator was designed using components such as LEDs, resistors, transistors, diodes, and an LM358 operational amplifier. The study adopted an experimental research design involving circuit design, construction, calibration, and testing of the device. The circuit was first assembled on a breadboard and later soldered onto a circuit board after successful testing. The results showed that the constructed device successfully indicated different battery charge levels. When the battery voltage was high, the yellow LED illuminated brightly to indicate a fully charged battery. At medium voltage levels, the yellow LED became dim, while at low voltage the red LED turned on to indicate low battery condition. The system responded effectively to voltage changes and consumed low power during operation. The study concluded that a reliable and effective battery level indicator can be constructed using simple and inexpensive electronic components. The device can help users monitor battery conditions, prevent over-discharge, and improve battery lifespan. The study recommends further improvement of the system through the use of microcontrollers, digital displays, and alarm systems for more accurate batter
Optimization of sound absorption using a combination of different locally available materials.
(Busitema University, 2026) Okiror, Jonathan
Noise pollution has emerged as a significant environmental and health concern in urban areas of Uganda, necessitating the development of effective and sustainable sound absorption solutions. This study investigated the optimization of sound absorption through the combination of different locally available materials. The research aimed at determining the physical properties (density and porosity) of selected materials, evaluate their individual sound absorption characteristics, and assess the absorption performance of combined material configurations. Three materials wood, polyester cloth, and sponge were selected for investigation based on their availability and acoustic potential. The density of each material was determined using dimensional measurements and mass weighing, while porosity was determined through the saturation method. Sound absorption was measured using an experimental setup comprising a signal generator, microphone, and cathode ray oscilloscope, following procedures adapted from ISO 10534-2 standards. Results revealed that sponge exhibited the highest porosity (85.3%) and lowest density (0.042 g/cm³), while wood showed the highest density (0.586 g/cm³) and lowest porosity (28.7%). Individual material testing demonstrated that sponge achieved the highest sound absorption, particularly at higher frequencies, while wood showed better absorption at lower frequencies. Combined material configurations demonstrated superior absorption across broader frequency ranges compared to individual materials. The wood-sponge combination showed the most promising results, achieving an absorption coefficient of 0.82 at 2000 Hz. These findings confirm that combining materials with complementary acoustic properties can optimize sound absorption performance. The study contributes valuable information on the acoustic properties of locally available materials and provides a foundation for developing sustainable, cost-effective sound absorption solutions for noise pollution control in Uganda.
Design and construction of a paper cutting device incorporating a charging system using locally sourced components.
(Busitema University, 2026) Wesonga, Emma
This project focused on the design and construction of a low cost paper cutting device incorporating a rechargeable charging system using locally sourced materials and electronic components. The study was motivated by increasing need for affordable and portable paper cutting equipment in schools, offices and small printing business enterprises, especially in areas with unstable electricity supply. The most available electric paper cutting Machines are expensive and difficult to maintain, while manual cutting tools require a lot of human effort and often produce inaccurate cuts. The device was constructed using a DC motor, rechargeable battery, charging circuit components such as resistors, capacitors, LEDs, diodes, USB charging port, breadboard, switch, double-edged blade, timber frame, wires, and adhesive materials. The charging system enabled the device to operate continuously even during power interruptions. A design and experimental research approach was adopted during the construction and testing of the prototype. Performance evaluation was conducted based on cutting efficiency, portability, safety, durability, and reliability of the charging system. The findings revealed that the constructed device was capable of cutting ten sheets of paper measuring 24 cm × 16 cm into smaller pieces of 2 cm × 2 cm within approximately three minutes. This was faster compared to ordinary manual scissors, which required about five minutes to complete the same task. The device also reduced direct hand contact with cutting blades, thereby improving user safety. The total cost of construction was approximately UGX 64,000, which is relatively cheaper than commercially available electric paper cutting machines. However, the device showed reduced efficiency when cutting thicker stacks of paper and lacked advanced safety guarding mechanisms. The study concluded that locally sourced materials can successfully be used to construct an affordable and functional paper cutting device with an integrated charging system. The study recommends further improvements such as incorporation of speed control mechanisms, protective blade covers, and automated paper feeding systems to improve efficiency and safety.
Analysis and testing of an improved charcoal stove with high thermal efficiency.
(Busitema University, 2026-09-05) Butuma, Elisaphani
In this study, an improved charcoal stove with high thermal efficiency was designed and tested as a cooking system that utilizes charcoal as its primary fuel while minimizing heat loss and fuel consumption. The system focuses on improving energy utilization rather than eliminating fuel use, making it a cost-effective and environmentally friendly alternative to traditional charcoal stoves. The constructed improved charcoal stove comprised of a combustion chamber, insulation layer, air inlet vents, pot support, outer casing, and other locally sourced materials. The stove was designed to enhance heat retention, regulate airflow, and improve combustion efficiency. An experimental setup was developed where two charcoal stove models were tested simultaneously using equal quantities of charcoal and water. Temperature measurements were taken at regular time intervals using thermometers inserted into the cooking pots to monitor heat transfer performance. The results obtained were recorded and analyzed to evaluate the efficiency of each stove. The improved charcoal stove demonstrated better performance by achieving a higher temperature of 60°C compared to 47°C from the other stove within 30 minutes of operation. This indicates improved heat transfer, reduced heat loss, and better fuel utilization. The efficiency improvement is attributed to enhanced insulation and controlled airflow, which ensure more effective combustion of charcoal. The study concludes that improved charcoal stoves can significantly reduce fuel consumption while increasing cooking efficiency. This technology is suitable for household use, particularly in areas where access to modern energy sources is limited. It provides a practical solution for reducing energy costs, minimizing environmental impact, and improving cooking performance among households and small-scale users.
Validation of Dst Prediction Model Run By Busitema University Space Science Center
(Busitema University, 2026-09-03) Onangole, Nathan
The Disturbance Storm Time (Dst) index is a critical measure of geomagnetic activity serving as a key indicator for space weather monitoring and forecasting. Accurate prediction of the Dst index is essential for mitigating the destructive effects of geomagnetic storms on technological infrastructure including satellite operations, power grids, communication systems and navigation networks. This research is about evaluation of Busitema University Space Weather Tool that has a capability of forecasting the Dst index among other metrics of space weather. Model data from Busitema University Space Weather Tool is evaluated against observation data obtained from OMNIweb run by NASA. The performance of the model was evaluated during quiet and disturbed days. The model demonstrated excellent predictive capability across both categories. A key observation is that the model achieved exceptional performance during intense storm conditions indicating almost perfect tracking of storm dynamics from onset to recovery. However a systematic negative bias was identified across the majority of events indicating a consistent tendency for the model to underestimate the magnitude of Dst extremes. This bias was more pronounced during disturbed days and quiet days with negative values for the daily average Dst index, suggesting that while the model effectively captures the trend of geomagnetic activity, it tends to under predict extreme values. This means that it is necessary to implement correction techniques to address the systematic underestimation. The strong correlation coefficients observed across all categories confirm the model's ability in tracking the overall trends and dynamics of the Dst index. The results of this research strongly indicate that the Busitema University Space Weather Tool is able to provide valuable information to support stakeholders affected by geomagnetic disturbances hence contributing to the protection of critical technological infrastructure against space weather hazards.
Fabrication of an electronic soil moisture sensor for efficient water management in crop production.
(Busitema University, 2026) Kajubi, Paul
This research presents the development and evaluation of an electronic soil moisture sensor designed to measure soil moisture content in a practical and accurate manner. The sensor utilizes a resistive sensing mechanism, where changes in soil moisture affect the electrical resistance between two probes, resulting in a corresponding voltage output. To ensure accuracy, the sensor was calibrated using a gravimetric method, where soil samples were weighed before and after oven drying to determine the moisture content percentage. The sensor demonstrated a linear relationship between soil moisture content and voltage output, with a high degree of accuracy and repeatability. The sensor employs a resistive sensing mechanism, where changes in soil moisture alter the electrical resistance between two embedded probes resulting in a corresponding voltage output. The sensor was constructed using two galvanized nails as the sensing probes, a 10k ohm resistor and a 5v power supply. Testing was conducted using soil samples prepared at five moisture levels that’s 0,25,50,75 and 100% moisture content by weight. Results showed that the sensor could clearly distinguish between dry soil and moist soil.
Design and construction of a fire sensor alarm using heat and flame detection.
(Busitema University, 2026-08-25) Namisano, Herbert
This study focused on the design and construction of a simple fire sensor using readily available electrical components to provide an affordable and efficient early fire detection system. The main objective was to develop a low-cost prototype capable of detecting fire conditions such as heat or flame and triggering an alarm to enhance safety in homes, schools, and small institutions. The study followed experimental procedures involving circuit design, construction, and performance testing under controlled conditions. The sensor was evaluated based on temperature variation, response time, sensitivity, accuracy, and reliability. The results showed that the system responded progressively to increasing temperature level, the findings further revealed that the use of locally available components significantly reduced construction cost while maintaining effective performance. In conclusion, the study demonstrated that a simple fire sensor can be effectively designed and constructed using basic electronic components, making it suitable for low-cost fire detection applications in resource-limited environments. Overall, the research contributes to the development of affordable safety technologies aimed at reducing fire-related risks and improving emergency response in developing regions.
Design and implementation of an automatic solar lighting system using basic electronic components.
(Busitema University, 2026) Watoboko, Samuel
Access to reliable electricity remains a challenge in many parts of Uganda, especially in rural areas where households rely on kerosene lamps and candles. Even where solar lighting systems exist, many require manual switching, leading to energy wastage and reduced battery life. This project aimed to design and implement an automatic solar lighting system using basic, affordable electronic components that can be locally sourced and repaired. The system consisted of an 8V solar panel, LM7805 voltage regulator, 1N4007 diode, 3.7V 18650 rechargeable battery, IRFZ44N MOSFET, resistors, and a 3V LED. The solar panel's own voltage was used to control the MOSFET, eliminating the need for a separate light sensor. During the day, the panel charged the battery while the LED remained off. At night, when panel voltage dropped, the MOSFET turned on, allowing current to flow to the LED. Testing was conducted at the Busitema University Physics Laboratory on 15th April 2025. Under bright sun (12:30 PM), the panel produced 8.2V, the battery charged at 4.1V, and the LED remained off. At dusk (6:45 PM), the LED began glowing dimly, and by 8:30 PM it was fully bright. The LED stayed lit for approximately 8 hours on a full battery. This project demonstrates that a functional, automatic solar lighting system can be built using basic components available in Ugandan local markets. The design eliminates manual switching, prevents energy wastage, and offers an affordable alternative to kerosene lighting for off-grid community.
Design and construction of a rain detector system using a BC148 transistor.
(Busitema University, 2026) Buyera, Eve Esther
Due to the rate of damages that occur to our industrials and homes possessions during rainfall. This rain alarm will give you an alarm indication the instant it starts to rain, hopefully giving you time to close windows and bring in possessions in our homes and to keep so many of our industrial machines in a proper place. The alarm has also the ability to indicate when it stops raining, by that time the alarm will stop. This project was designed to indicate when it is raining and also to indicate when the rain has stop. Apart from these two applications, there are other applications that this alarm has which would be mentioned in this work.
Construction of a simple electrochemical cell using carbon rods and zinc plates from used dry cell.
(Busitema University, 2026-05) Ongago, Shaffi Okonyo
This study focused on the design and construction of a simple electrochemical energy source for household lighting using carbon rods and zinc plates extracted from used dry cells. The study was motivated by the limited access to reliable electricity in many Ugandan households, especially in rural areas, and the increasing disposal of used dry cells which contribute to environmental pollution. The project aimed at recycling useful battery materials to construct a low-cost source of electrical energy for lighting purposes while demonstrating practical application of electrochemical principles. The specific objectives were to design an electrochemical cell using recycled zinc and carbon electrodes, integrate the constructed cell with a 24 V rechargeable battery and inverter to increase voltage output, and evaluate the performance of the system by measuring voltage, current, power output, and lighting duration. Carbon rods and zinc plates were extracted from used dry cells, cleaned, and immersed in a sodium chloride electrolyte solution prepared using distilled water and common salt. The electrodes were connected to an external circuit, charged using a 24V battery, and linked to an inverter to power LED bulbs. Measurements were taken using a digital multimeter to determine system performance. Findings indicate that recycled dry cell materials can generate usable electrical energy for low-power household lighting. The study demonstrated the practical application of electrochemical energy conversion and practical learning of electrochemistry concepts in physics education
ANALYSIS AND TESTING OF AN IMPROVED CHARCOAL STOVE WITH HIGH THERMAL EFFICIENCY
(Busitema University, 2026-06-06) Butuma, Elisaphani
In this study, an improved charcoal stove with high thermal efficiency was designed and tested as a cooking system that utilizes charcoal as its primary fuel while minimizing heat loss and fuel consumption. The system focuses on improving energy utilization rather than eliminating fuel use, making it a cost-effective and environmentally friendly alternative to traditional charcoal stoves. The constructed improved charcoal stove comprised of a combustion chamber, insulation layer, air inlet vents, pot support, outer casing, and other locally sourced materials. The stove was designed to enhance heat retention, regulate airflow, and improve combustion efficiency.An experimental setup was developed where two charcoal stove models were tested simultaneously using equal quantities of charcoal and water. Temperature measurements were taken at regular time intervals using thermometers inserted into the cooking pots to monitor heat transfer performance. The results obtained were recorded and analyzed to evaluate the efficiency of each stove.The improved charcoal stove demonstrated better performance by achieving a higher temperature of 60°C compared to 47°C from the other stove within 30 minutes of operation. This indicates improved heat transfer, reduced heat loss, and better fuel utilization. The efficiency improvement is attributed to enhanced insulation and controlled airflow, which ensure more effective combustion of charcoal.The study concludes that improved charcoal stoves can significantly reduce fuel consumption while increasing cooking efficiency. This technology is suitable for household use, particularly in areas where access to modern energy sources is limited. It provides a practical solution for reducing energy costs, minimizing environmental impact, and improving cooking performance among households and small-scale users.
DESIGN AND DEVELOPMENT OF A PORTABLE SOLAR MOBILE CHARGER.
(Busitema University, 2026-06-06) Soita, Jonathan
The increasing dependence on mobile phones for communication, education, and business has created a growing demand for reliable charging solutions, especially in areas with limited or unreliable electricity supply. This study focused on the design and development of a simple and cost-effective battery-less solar mobile charger powered by solar energy. The system was developed using a 7 V solar panel, an LM7805 voltage regulator, capacitors, resistors, a diode, and a USB charging interface to provide a regulated output suitable for mobile phone charging. The performance of the system was evaluated under varying sunlight conditions by measuring the input voltage, output voltage, and output current at different times of the day. The results showed that the charger performance depended strongly on solar radiation intensity, with output voltage and current increasing toward midday. The maximum output voltage and current obtained were 4.89 V and 117.7 mA, respectively, recorded at 2:00 PM. Although the system successfully converted solar energy into electrical energy, the output current was lower than the charging requirements of most modern smartphones, resulting in slow charging. Nevertheless, the study demonstrated the potential of solar energy as a sustainable and environmentally friendly source of power for low-power electronic devices in off-grid areas. The study recommends the use of larger solar panels, improved voltage regulation methods, and energy storage systems to enhance charging efficiency and system reliability.
Design and construction of a mortor-based DC volatage step-up system
(Busitema university, 2026) Masawo, David
This study presents the design and construction of an electromechanical DC Voltage step-up system that converts low-voltage direct current (DC) inputs into higher output voltage using coupled vibrational and DC motors. The system operates by converting electrical energy from a low-voltage source into mechanical energy through vibrational motor, which in turn drives a DC motor functioning as a generator to produce a higher output voltage The developed prototype demonstrated the ability to increase an input voltage of approximately 3.7V to a maximum output voltage of about 20V under no-load conditions. Under load conditions (12V load), the output voltage was observed to be approximately (12.5V) indicating the effect of load resistance on system performance. The efficiency of the system was evaluated based on the ratio of output power to input power and was found to be in the range of (40%-50%) depending on operation conditions. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow (Forouzesh et al. 2017). Additionally, the system exhibited voltage fluctuations attributed to the nature of mechanical coupling between the vibrational motor and the DC motor. Overall, the proposed system provides a simple and cost-effective approach to voltage step-up through electromechanical energy conversion. The findings demonstrate its potential for educational applications and low-power systems, while also identifying key limitations related to efficiency and stability that can be improved in future work. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques (Hsieh et al. 2013) . The findings of this research provide valuable insights into energy conversion technologies and offer a practical solution for educators and developers seeking to utilize low-voltage power sources. This project lays the groundwork for future advancements in simple voltage boosting systems, promoting innovation in the fields of electronics and renewable energy applications. However, the operation of these system is affected by various factor such as unstable power supply (weak battery), (Gurgi, Abdalla, and Hassan 2023).
Design,construction and perfomance evaluation of a Non-contact AC voltage detector
(Busitema university, 2026-06-05) Mande,Emmanuel
This study presents the design and construction of a non-contact AC detector capable of identifying live conductors without physical contact. The device operates on the principle of electromagnetic induction whereby a varying electric field around an energized conductor induces a small signal in a sensing probe. The induced signal is amplified using a transistor-based circuit to activate visual and audio indicators (LED and buzzer). The detector was constructed using discrete components and tested at various distances from AC conductors within the range of 110–220 V. Experimental results showed that the device successfully detected AC voltage up to 14 cm with output voltage ranging from 0.03 V to 0.24 V from a live Ac carrying conductor demonstrating its usefulness as a low-cost safety tool for electrical maintenance.
Extraction and preparation of a low-cost functional dye sensitized solar cell.
(Busitema University, 2026) Watsena, Silva
This report explores the development of Dye-Sensitized Solar Cells (DSSCs) using natural dyes as low-cost, eco-friendly alternatives to expensive and toxic synthetic sensitizers. Various natural pigments, including anthocyanins from rosella and guinea sorrel, battalions from beetroot, and curcumin from turmeric, were extracted and analyzed. Research indicates that the extraction solvent, pH levels, and the use of dye combinations significantly influence the efficiency of the solar dye. The highest reported efficiency for a natural dye combination was 2.71% for a beetroot and turmeric mixture at an acidic
DESIGN AND EVALUATION OF PHYSIO-MECHANICAL, THERMAL, AND BIODEGRADABILITY PROPERTIES OF BIOBOXES FOR SUSTAINABLE DOMESTIC FOOD STORAGE
(BUSITEMA UNIVERSITY, 2026-06-03) MWESIGWA SIMEON
This study aimed to design and evaluated biodegradable bio-boxes using locally available materials for sustainable domestic food storage in Uganda. The research investigated physio mechanical properties, thermal performance, and biodegradability of the fabricated bio-boxes. Materials such as cassava starch, banana fibers, and paper pulp were used to produce bio-boxes. Mechanical tests showed moderate tensile strength suitable for domestic use, while thermal analysis revealed low thermal conductivity, indicating good insulation properties. Biodegradability tests demonstrated decomposition within 4–8 weeks under soil burial conditions. The study aligns with Uganda’s environmental policies, including the National Environment Act (2019), promoting sustainable alternatives to plastic packaging. The findings confirm that bio-boxes are a viable ecofriendly solution for reducing plastic waste in domestic food storage.
Analysis of the radiological content in selected floor tiles and cement brands commonly used in building construction in Tororo, Uganda.
(Busitema University, 2024) Waiswa, Salimu
In this study, cement and floor tiles that are frequently used in building construction were investigated using a NaI (TI) detector in gamma ray spectrometry to identify the gamma ray emitting radionuclides of Ra-226, Th-232, and K-40 as well as radiological parameters of radionuclide activities concentration, radium equivalent activity, absorbed gamma dose, annual effective dose, external and internal hazard indices, excess lifetime cancer risk, and annual gonadal equivalent dose. In the study, samples of cement and floor tiles from different cement and tile manufacturers were evaluated. Using the NaI (TI) detector, naturally occurring radionuclides of radium (Ra-226,), thorium (Th-232) and Potassium (K-40) were found in all the analyzed samples. The radionuclide activity concentration of Ra-226, Th-232, and K-40 in cement were in the range of 10.2± 0.7 Bqkg-1 to 86.1± 4.3 Bqkg-1, 28.9± 1.3 Bqkg-1 to 105.3±, 2.5 Bqkg-1 and 334.2± 6.4 Bqkg-1 to 508.5± 7.9 Bqkg-1, with average values of 31.2± 1.7 Bqkg-1, 61.9± 1.9 Bqkg-1 and 463.1± 7.5 Bqkg-1 respectively. Save for Ra-226 whose average activity concentration was less than 40 Bqkg-1 the global average value, the activity concentrations of Th-232 and K-40 recorded were higher than 35 Bqkg-1 and 400 Bqkg-1, the global recommended dose limits respectively. The average value of the absorbed dose rate, annual effective dose, radium equivalent activity, external and internal indices in the analyzed cement samples were 71.1± 2.2 nGyhr-1, 0.349± 0.011 mSvy-1, 155.3± 5.1 Bqkg-1, 0.42 and 0.50 below the maximum permissive dose limit of 84 nGyhr-1, 1.0 mSvy-1, 370 Bqkg-1 and 1(unity) respectively. The recorded average values of the excess life time cancer risk and annual gonadal equivalent dose were and 0.50 mSvy-1 which are above the recommended dose limit of and 0.3mSvy-1 respectively. In the floor tile samples, the concentration of radionuclide activity for Ra-226, Th-232, and K-40 ranged from 13.2± 0.8 Bqkg-1 to 49.0± 2.4 Bqkg-1, 38.7± 1.3 Bqkg-1 to 149.5± 3.7 Bqkg-1, and 192.9± 2.6 Bqkg-1 to 526.7± 8.0 Bqkg-1, with average values of 30.8± 1.4 Bqkg-1, 95.8± 2.3 Bqkg-1, and 388.6± 6.2 Bqkg-1, respectively. Th-232 was found to have average activity concentration above the global recommended dose limits of 35 Bqkg-1, with the exception of Ra226 and K-40, whose average activity concentrations were less than the global average value of 40 Bqkg-1 and 400 Bqkg-1, respectively. In the examined floor tile samples, the average values of the absorbed dose rate, annual effective dose, radium equivalent activity, external and internal indices were 88.3± 2.3 nGyh-1, 0.43± 0.011 mSvy-1, 197.7± 5.2 Bqkg-1, 0.534, and 0.458, respectively, which are below the maximum permissive dose limit of 84 nGyhr-1, 370 Bqkg-1 and 1(unity). The average reported values of the excess life-time cancer risk and the annual gonadal equivalent dose were 1.52x10-3 and 0.619 mSvy-1, respectively beyond the suggested dosage limit of 0.29x10-3 and 0.3 mSvy-1. Due to some samples showing higher activity concentrations than the global average, further studies are recommended to confirm these findings and assess additional radiological parameters like alpha and gamma indices. Future research should include more types of building materials. High radionuclide activity in some samples poses significant health risks, such as increased cancer rates, radiation sickness, genetic damage, respiratory problems, reproductive issues, and cardiovascular disease, particularly for those living in buildings made with such materials.
Optimizing density, water absorption and compressive strength of paving blocks molded from plastic waste to address plastic pollution
(Busitema University, 2024) Ronald, Henry Kibiina
The production and usage of plastics are rapidly increasing in our daily lives, leading to significant disposal challenges, including landfill overflow, environmental pollution, microplastic formation, emissions from incineration, and increased economic costs associated with waste management. This study, therefore, aims to mitigate these effects by investigating the optimization of the physical properties of paving blocks molded using plastic waste as a binding material, thus offering a sustainable solution for plastic disposal through construction. Two types of waste plastic materials were used: Polyethylene Terephthalate (PET) and Polyvinyl Chloride (PVC). Additionally, two sand particle sizes, 0.5 mm and 1.2 mm, were selected to comprehensively evaluate their impact on the physical properties of the paving blocks and to identify the optimal mixture for enhanced performance. These particle sizes represent a range of fine and coarse sand, allowing for a thorough investigation of how varying sizes influence the response variables. PET plastic was collected from disposal points, dustbins, and surroundings in Tororo municipality while PVC from construction sites still in Tororo municipality, Eastern Uganda, while the sand was sourced from a construction site at Tororo Girls’ School in Tororo municipality. The molten waste plastic and sand were mixed in different proportions based on Central Composite Design (CCD), a statistical method within Response Surface Methodology (RSM) that systematically explores multiple factors affecting response variables, ensuring the optimal combination for the desired physical properties. RSM was employed to analyze the experimental data and model the relationships between the variables, enabling the identification of optimal conditions for achieving the desired physical properties, (density, water absorption, and compressive strength) of the paving blocks. Models were developed to fit the experimental results, with all density models being successful. The water absorption model for PET was successful for both sand particle sizes, the water absorption model for PET was successful for both sand particle sizes; in contrast, no model could be established for PVC molded pavers, as absorption values consistently registered at 0.000 across all composition ratios. This outcome indicates that the hydrophobic nature of PVC not only contributes to its resistance to water absorption but also facilitates effective bonding of sand particles, without pore spaces formation. Only the combination of PET with a sand particle size of 1.2 mm produced a successful model for compressive strength, while other combinations did not yield satisfactory results. This combination exhibited successful models for all evaluated responses, highlighting its potential as the optimal combination for molding the desired paving blocks. Using the Response Surface Methodology (RSM), the optimal combination for molding the paving blocks was determined to be 148.28 g of sand and 50.0 g of PET plastic, which meets the parameters of low density, low water absorption, and high compressive strength. The results imply that utilizing plastic waste as a binding material in paving blocks not only offers a sustainable solution for reducing plastic waste but also producing high performance pavers, thereby addressing the critical issue of plastic pollution while creating durable paving blocks.
Weighted Mean Temperature Models for estimating Global Navigation satellite System Precipitable Water Vapor over East Africa
(Busitema University, 2024) Peter, Mbayo
The weighted mean temperature (Tm) is an important parameter in deriving accurate and reliable Global Navigation Satellite System (GNSS) Precipitable Water Vapor (PWV) values especially in tropical regions. However, the accuracy of GNSS - PWV in the East African region is limited by the availability of precise and reliable meteorological data for computing accurate Tm values. To address this limitation, this study developed site-specific regional Tm models for East Africa (E.A) using radiosonde and Ozonesonde profiles from 1971 to 2019. The models were validated using radiosonde profiles from two stations 63741 (Dagoretti) and 63894 (Dares-salaam) based on Root Mean Square Error (RMSE) and Mean Bias Error (MBE) values of Tm. The Tm values from the established models were compared with the two global (Bevis and Yao) and one Tropical regional (Raju) Tm models in order to assess their performance. At station 63741, the RMSE of the E.A model, the site-specific Tm model, the Bevis, Yao, and Raju Tm models are 2.01 K, 1.76 K, 1.79 K, 2.54 K, 2.74 K, and 2.47 K, respectively. At station 63894, the RMSE of the E.A model, the site-specific Tm model, the Bevis, Yao, and Raju Tm models are 1.66 K, 1.63 K, 1.70 K, 2.52 K and 2.64 K, respectively. At both stations, the site-specific Tm models have higher accuracy followed by the E.A model as compared to Raju Tm model and the two global T of Tm models (Bevis and Yao). The study further evaluated the accuracy models in the retrieval of PWV by computing PWV values at three GNSS sites (ARSH, DODM, and RCMN). The GNSS - PWV values computed from different Tm models were compared with PWV values derived using Tm from ERA5 reanalysis dataset from 2013 to 2020. The use of GNSS-PWV from ERA5-Tm as the reference values was due to the limited Tm values from Radiosonde during the same periods of available GNSS data required for PWV estimation. In terms of RMSpwv, the site-specific models exhibit values ranging from 0.107 mm to 0.11 mm, with a mean value of 0.109 mm, which is the lowest among the five models. This is followed by, the E.A regional model with mean value of 0.127 mm, Yao Tm with a mean value of 0.129 mm, Bevis with a mean value of 0.130 mm, and Raju with a mean value of 0.148 mm. The results show that the E.A regional Tm model and site-specific models perform better than the global and other tropical regional Tm models. Therefore, the established Tm models are the preferred choices for estimating for GNSS - PWV retrieval in the East African region. Overall, the study provides improved Tm models for accurate estimation of GNSS - PWV in the East African region, which could improve weather and climate forecasts.

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