Collage of Pure and Applied Sciences (COPAS)

Agronomic activities and Seasonal Variations on Abundance and Diversity of bee Species and the state of knowledge of pollinator importance in Loitokitok Sub-County, Kenya

2026-05-28T10:22:31Z

Agronomic activities and Seasonal Variations on Abundance and Diversity of bee Species and the state of knowledge of pollinator importance in Loitokitok Sub-County, Kenya Aika, Charles Omari Honey bees are prone to agronomic activities such as misuse of agrochemicals, land fragmentation, alteration of natural habitats and change in land use patterns. Understanding how bee species respond to habitat destruction is significant towards development of effective measures to ensure that the environment is protected and conserved. The study sought to assess the effects of agronomic activities and seasonal variations on abundance and diversity of bee species and the state of knowledge of pollinator importance in Loitokitok sub-county, Kenya. Experimental research design comprising of three different habitats was conducted in order to establish effects of agronomic activities on bee abundance and diversity and state of knowledge of pollinator importance in Loitokitok Sub-County, Kenya. The study aimed at evaluating the effect of agronomic practices on the diversity and abundance of bee species, determining the impact of seasonal weather variations on abundance and diversity of bee species and assessing the state of knowledge of pollinator importance among small-holder farmers in Loitokitok sub county, Kenya. The study area was stratified into three habitats (1) cultivated farm, (2) rangeland (3) natural forest. A survey of the study area was done and the habitats identified. A sample area of 1 × 1 km square was picked at random from each of the three study areas. The selected areas were further sub-divided into 0.5 × 0.5 km smaller study areas and a total of 3 belts were laid down randomly within the small study areas. Sampling of the bees was done for 3 months using a sweep net and pan traps to collect the bee species. Shannon Weiner diversity index was used to compute diversity and richness of honey bee species. One way ANOVA was used to compute the statistical significance of bee species abundance across the three habitats. A total of 1,106 bee specimens from 2 families and 7 species were collected from the three study habitats. Apis mellifera, was the most abundant bee species followed by Pseudapis spp., Lasioglossum spp., Xylocopa spp., Braunsapis spp., Ceratina spp. while Heriades spp. was the least abundant bee species. Natural edge habitat had the highest bee species abundance followed by rangeland while cultivated habitat had the least bee species abundance. Cultivated habitat recorded highest diversity index, H/= 1.511 followed by rangeland with H/= 1.424 while the natural habitat had the least at H/= 1.351. However, the overall diversity index was H/= 1.43. There was a statistical significance (p<0.05) between cultivated habitat & rangeland, cultivated habitat & natural forest edge and also between rangeland & natural forest edge respectively. Seasonal weather changes influenced bee species abundance and diversity in the study area. The bee species abundance and diversity were greater during the rainy season as compared to the dry season. This study reveals that agronomic activities had an influence on bee species abundance and diversity. Farmers demonstrated substantial knowledge of bees, with about 90% identifying different species and recognizing nest sites and food resources. More than 86% had experience in honey harvesting, while most understood the importance of bee visits to crops and live fence flowers. Notably, 90.9% expressed willingness to promote bee populations on their farmlands. Therefore, the local community, farmers and other stakeholders should be sensitized on the importance of bee conservation and its contribution to their welfare and on utilization of cost-effective approaches towards bee management and conservation. Master of Science in Zoology (Conservation Biology)

Optimizing Wso2 Api Manager for Improved Graphql Query Performance in a Distributed Setup

2026-05-26T10:54:05Z

Optimizing Wso2 Api Manager for Improved Graphql Query Performance in a Distributed Setup Ondero, Stanley Makori In the rapidly evolving landscape of API management, GraphQL has emerged as a powerful query language that enables efficient data retrieval. However, optimizing GraphQL query performance within the context of distributed WSO2 API Manager remains a significant challenge. This research aimed to address this challenge by investigating the performance bottlenecks of GraphQL queries in WSO2 API Manager and proposing a comprehensive optimization model. The study begins by conducting a thorough literature review to identify existing performance challenges and potential optimization techniques. Through empirical testing and analysis, a baseline performance profile is established, highlighting key areas for improvement. The proposed optimization model encompasses three main components: JVM optimization, query splitting algorithm, and caching mechanisms. JVM optimization focuses on tuning parameters such as heap size and garbage collection settings to enhance resource utilization. The query splitting algorithm which exploits parallel execution to enhance performance was applied. Caching mechanisms, implemented using Redis, enable efficient storage and retrieval of frequently accessed data, minimizing redundant database queries. The effectiveness of the optimization model was evaluated using the M-PESA Payment API as a real-world test case. Experiments were conducted under various concurrency levels, measuring key performance metrics such as response time, throughput, and error rate. The optimized performance was compared against the baseline, revealing significant improvements. The model achieves an average response time reduction of 4.62% and throughput growth of 5.89%, demonstrating its efficacy in enhancing GraphQL query performance. This study evaluates three complementary techniques in a distributed WSO2 API Manager: (i) server-level optimization (OS TCP tuning and JVM G1GC with fixed heap), (ii) query splitting for parallel sub‑resolution of GraphQL fields, and (iii) Redis-based distributed caching for tokens and hot query results. Master of Science in Computer Systems

Analysis of Power System Network Stability In Rwanda

2026-05-21T12:33:26Z

Analysis of Power System Network Stability In Rwanda Bizimungu, Silas Power system stability is a critical requirement for ensuring reliable and secure electricity supply, particularly in developing power systems experiencing rapid demand growth and increasing penetration of renewable energy sources. This study evaluates the stability of Rwanda’s electricity grid with a focus on transient, voltage, and frequency performance under realistic operating and disturbance conditions. A detailed model of Rwanda’s national power system was developed using Power System Simulator for Engineering (PSS®E), incorporating actual network parameters for generation, transmission, substations, and load centres. The model was verified and validated against available SCADA measurements before being subjected to steady-state power flow analysis and time-domain dynamic simulations. Stability performance was assessed under peak and off-peak loading conditions, generator and line outages, and renewable generation disturbances. The results show that the transmission network is generally lightly loaded, with maximum line loading of approximately 25% during off-peak and 46% during peak conditions; however, localised infrastructure constraints exist at critical substations, where transformer loading reaches up to 96% under normal operation and exceeds 130% under N-1 contingencies. Voltage stability analysis reveals widespread off-peak overvoltage, with several 110 kV busbars exceeding 120 kV, while dynamic simulations indicate slow voltage recovery following disturbances. Transient stability assessment demonstrates adequate stability margins, with critical clearing times ranging from approximately 200 ms to over 1000 ms, exceeding typical protection clearing times. Frequency stability analysis identifies limited spinning reserve as a major vulnerability: system frequency drops to 48.83 Hz following loss of 6.5 MW of solar generation when only 4 MW of reserve is available, necessitating under-frequency load shedding for recovery. The study further demonstrates that targeted mitigation measures significantly improve stability. The installation of shunt reactive power compensation reduces overvoltage and improves post-fault voltage recovery, while increased local generation or reserve capacity mitigates frequency excursions and reduces dependence on load shedding. Overall, the findings confirm that while Rwanda’s electricity grid possesses adequate transient stability, its operational performance is constrained by reactive power management challenges, low reserve margins, and topology sensitivity. The study provides practical insights for system operators and planners on improving voltage and frequency stability through targeted network reinforcement and operational strategies Master of Science in Energy Technology

Attenuation of Irradiance by Water for Potential Solar Photovoltaic Systems Applications

2026-05-21T11:21:34Z

Attenuation of Irradiance by Water for Potential Solar Photovoltaic Systems Applications Raduk, Sally Awuor This study explores the feasibility of submerged photovoltaic (PV) systems as a supplementary energy source for autonomous underwater vehicles (AUVs), which are widely used in ocean exploration, remote sensing and marine monitoring. Given the limited operational durations of conventional energy sources like lithium-ion batteries and piezoelectric propulsion, the integration of PV systems offers potential for extended deployment by harnessing solar irradiance in the upper water column. The research combines theoretical modeling and experimental analysis to investigate irradiance attenuation through water samples with varying densities (1036, 1025 and 1000 kg/m^3), represented by attenuation coefficients of 0.2,0.1 and 0.04 m^(-1) respectively. A submerged polycrystalline photovoltaic (PV) system was tested under these conditions, and water properties for all samples, including pH (7.65), salinity (0.03 psu), total dissolved substances (TDS) (25.6 ppm), conductivity (51.3 μS/cm), and resistivity (19.3 kΩ.cm) - were measured for their influence on irradiance attenuation as it propagates through the media. Potassium and sodium concentrations were inferred as 2.8 ppm and 12 ppm using emission intensity calibration. Results showed a notable irradiance drop from 1000 W/m^2 (air mass AM 1.5) to 450 W/m^2 at the surface and 360 W/m^2 at 18 cm depth, with a maximum power output of 37 W, which is sufficient for many shallow-water AUVs requiring 20-200 W. These findings highlight the critical role of water composition and depth in optimizing underwater solar energy harvesting, supporting the advancement of sustainable power solutions for persistent marine operation. Master of Science in Physics