Institutional-Repository, University of Moratuwa
Welcome to the University of Moratuwa Digital Repository, which houses postgraduate theses and dissertations, research articles presented at conferences by faculties and departments, university-published journal articles and research publications authored by academic staff. This online repository stores, preserves and distributes the University's scholarly work. This service allows University members to share their research with a larger audience.
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Recent Submissions
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Investigating the effect of W/C ratio in producing cement blocks using BA from waste to energy plant
(IEEE, 2024) Walpitagama, WGAS; Baskaran, K
Bottom Ash (BA), a byproduct of coal or solid fuel combustion in power plants, poses environmental and health risks due to inadequate disposal methods. Utilizing BA in manufacturing cement blocks offers a promising solution. This study investigates the optimal water/cement ratio for producing blocks using BA as a partial substitute for fine aggregate. It assesses BA characteristics and examines the mechanical, and durability properties of the blocks. The research produces solid cement blocks measuring 300 mm × 100 mm × 150 mm, with water/cement ratios ranging from 0.8 to 1.4 in the conventional table vibratory method and 0.6 to 1.4 in the hydraulic compaction method. Results show that increasing the water/cement ratio leads to increased density, compressive strength, tensile strength, and moisture content up to 1.2 water/cement ratio and reduced after in conventional table vibratory method and up to 1.0 water/cement ratio and reduced after in hydraulic compaction method. The analysis suggests that, for small and medium-scale conventional cement block production for loadbearing walls of residential buildings up to four storeys the conventional table vibratory method can be used and it can be extended up to five storeys using the hydraulic compaction method.
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Motion control of an unmanned catamaran vessel for maritime environment
(IEEE, 2024) Sanjaya, HMS; Jayasekara, P
This study aims to check the behaviour of various controllers that can successfully control a catamaran vessel on the ocean surface for trajectory tracking. Unlike on the ground, the ocean surface has disturbances from water currents, wind forces and ocean waves. Therefore, trajectory tracking is challenging work. A 3D model of a catamaran vessel was simulated to check the vessel’s behaviour with the controllers: Polynomial recurrent neural network-based adaptive PID controller, first and secondorder sliding mode controllers, and first-order adaptive controller are among them. The control system is a combination of two controllers. The primary controller controls the vessel’s surge and yaw according to the velocity error. The secondary controller controls the velocity errors required by the primary controller, according to the displacement error of the catamaran vessel from the trajectory and the required forward velocity of the catamaran vessel. The simulation results show the comparison of different combinations of primary and secondary controllers. It is identified that the yaw control of the catamaran and the secondary controller was the most critical and, thus, candidates for further development.
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Capacitive response study of ZnO based metal-semiconductor-metal ultraviolet photodetector
(IEEE, 2024) Thalayarathna, DRC; Samintha, MMD; Attygalle, D; Amarasinghe, DAS
In the dynamic domain of sensor technology, the integration of customized ultraviolet (UV) light detectors utilizing easily synthesizable metal oxide presents a transformative advantage in the optoelectronic landscape. This research elucidates the promising potential of Zinc Oxide (ZnO) as a transducer material for integrated optical technologies, expanding the horizon of integrated optical sensor systems and offering a streamlined approach to embedding light detectors into optoelectronic devices. At the heart of this study lies the development of a capacitive metal-semiconductor-metal (MSM) ultraviolet photodetector (UVPD), harnessing the exceptional properties of ZnO as the foundational semiconductive material. The detector demonstrates a notable optical response, particularly prominent around 386 nm, aligning closely with ZnO's calculated optical band gap. The simplicity of fabrication renders this detector system highly suitable for industrial optoelectronic applications. The precise printing capability of ZnO within integrated systems facilitates the creation of builtin transducers, effectively converting light signals into electrical signals. This feature enhances sensitivity and accuracy while streamlining system miniaturization efforts.
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Automated voltage control for a distribution network using volt-var mode of smart inverters
(IEEE, 2024) Chandrasekara, AAU; Hettiarachchi, VS; Dinushan, HDK; Wadduwage, DP
Increasing penetration of Distributed Energy Resources into present-day distribution networks may introduce voltage issues, especially over voltage situations. Hence the power quality may be affected. The system can depend on slow-responding legacy devices such as on-load tap changing transformers and capacitor banks for voltage regulation. But they cannot be operated on regularly as it may reduce their lifetime. Therefore, a contribution from smart PV inverters can be obtained for a faster response. This paper focuses on obtaining a contribution from smart inverters along with dispatching of legacy devices optimally using a Deep Q Network agent. A modified IEEE 123 node test feeder is used to validate the suggested framework where PV systems are embedded in each and every node. It is compared with multiple cases to verify the effectiveness of the suggested technique. The results assure that the voltages of almost all the nodes are well within the acceptable range (0.95pu –1.05pu).
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A Comparative performance analysis of heaving point absorber and oscillating wave surge type wave energy converters in irregular Sri Lankan wave conditions
(IEEE, 2024) Manawadu, NHDS; Nissanka, ID; Karunasena, HCP
As an island surrounded by the Indian Ocean, Sri Lanka has significant potential to harness wave energy as a renewable energy source. However, limited research has been conducted on suitable wave energy converter (WEC) types under local wave conditions. This study analysed the performances of two main WEC types: Heaving Point Absorber (HPA) and Oscillating Wave Surge Converter (OWSC) in a sea location near Matara, a southern coastal area of Sri Lanka. The HPA performance was evaluated using a conventional cylindrical buoy and a novel super cuboid shape, which was found more efficient in previous studies. Similarly, for the OWSC, conventional rectangular flap was compared with a novel concaved flap geometry, also previously proven to be more efficient. The analysis employed Smoothed Particle Hydrodynamic (SPH) numerical simulations, with 266 simulations conducted under various operational conditions, including damping coefficients, Buoy Height to Wave Height Ratio (BHWHR), and buoy or flap widths. Results indicated that using a super cuboid buoy and concaved flap could increase the capture width ratio (CWR) by up to 25% compared to conventional geometries. The study concludes that HPA-type WECs are the best candidates for local wave conditions, considering CWR, hydrodynamic forces, and directional variations of the waves.