2026-02-25
K. M. Muditha Dassanayake, Jayamini Henapola
Aluminum ingot feeding systems are vital for ensuring efficient and controlled melting processes in aluminum production. This work presents a novel CAM-controlled ingot feeding unit specifically designed for furnaces employing non-oxidation melting technology. The system is composed of two primary units: a conveyor system for feeding to the input unit, and an input unit that consists of chucking (vice) units, conveyor chain, and a CAM unit with a special profile. When using 5 kg ingots, the system is capable of feeding up to 900 kg per hour. Spring-tensioned two-jaw vices are used to securely clamp the ingots during feeding. Up to three vices can be employed simultaneously, and they can be easily mounted onto the conveyor chain as required by the application. The conveyor chain speed of the input unit is adjustable via a motor inverter, allowing precise control of the ingot feeding rate to the furnace. The clamping and unclamping mechanisms are actuated by a cam unit with a specially designed profile, ensuring synchronized and reliable operation. The entire unit is engineered for easy installation onto the furnace structure. After fabrication, the system was tested continuously over a six-day period, and the results demonstrated that it is highly suitable for use in a production environment.
2026-02-25
P. A. K. Karunananda
No abstract available
2026-02-25
Isuru Munasinghe, Ashen Rodrigo, J. P. Karunadasa
The increasing demand for compact, efficient, and cost-effective power conversion systems across sectors such as renewable energy, industrial automation, and telecommunications has highlighted the need for high-performance DC-DC converters. This paper presents the design, implementation, and experimental validation of a 500 W half-bridge LLC resonant DC-DC converter for 63-75 V input and a regulated 14.5 V output. A key feature of the design is resonant-tank optimization to maintain inductive-region operation and allow soft switching, with experimental evaluation of the soft-switching margin that identifies where ZVS degrades near high-load operation. The incorporation of GaN FETs allows 100 kHz operation with peak efficiency above 90%, and a controlled GaN-versus-MOSFET comparison on the same platform under identical conditions shows a load-dependent efficiency improvement that increases toward higher output power, ranging from approximately 1% to 10%. Practical high-frequency hardware effects, including gate-drive and auxiliary-winding oscillations, are characterized and mitigated using a simple decoupling-and-gate-tuning approach. In addition, an adaptive protection framework is integrated, including configured input over- and under-voltage thresholds and multi-level over-current protection, to provide safe operation. Experimental validation through efficiency measurements and dynamic-load testing confirms stable behaviour over the tested operating range.
2026-02-25
L. G. C. Madhushan, U. P. Nawagamuwa, M. D. J. P. Wickramasooriya
Riverbank protection is becoming a significant environmental challenge in Sri Lanka. Although structural solutions have been commonly applied for slope stabilisation, many approaches using Nature-based Solutions (NbS) have been employed by humans for a long time to enhance riverbank stability as sustainable and ecologically practicable solutions. As an NbS, this research investigates the mechanical stabilisation potential of Hibiscus tiliaceus through field assessments and numerical modelling. Hibiscus tiliaceus is a native species that has been traditionally used in Sri Lanka. Field observations along the Kelani River (Hanwella to Kaduwela) showed that sections with Hibiscus tiliaceus displayed enhanced stability compared to non-vegetated areas. Numerical analysis was conducted using SLOPE/W software, simulating three slope geometries (1V:1H, 1V:1.5H, 1V:2H) under four hydraulic conditions: low flow, mid flow, full flow, and rapid drawdown in the river. The root reinforcement was modelled by incorporating depth-varying apparent cohesion based on literature-derived parameters. Results showed that vegetated slopes have consistently higher Factors of Safety (FoS), particularly on steep slopes under rapid drawdown. The findings highlight the importance of Hibiscus tiliaceus as a sustainable, cost-effective NbS for riverbank protection and offer a pathway for integrating tree vegetation into riverbank failure control strategies in Sri Lanka.
2026-02-25
M. S. S. Perera, B. G. L. T. Samaranayake, W. A. N. I. Harischandra
This paper presents a comparative study of eight visual servoing control schemes for robotic manipulation involving complex star-shaped object tracking. Three main approaches—Image-Based Visual Servoing (IBVS), Position-Based Visual Servoing (PBVS), and hybrid methods are analysed under fixed and adaptive gain configurations. Novel techniques include smoothing, adaptive blending, and damped least squares (DLS) inversion. Experiments were conducted in MATLAB using a 6-DOF PUMA-560 manipulator with an eye-in-hand camera tracking a 16-point asymmetric star-shaped target. Evaluation metrics covered convergence, computational efficiency, positioning accuracy, trajectory smoothness, and stability. Results show that the hybrid adaptive smoothing method outperforms others, achieving 23 − 31% faster convergence, lowest final error (0.0008 m vs. 0.0015–0.0025 m), 45% lower velocity variation, 38% fewer control discontinuities, and a 35% lower condition number, while maintaining computation time within 5% of fixed-gain schemes. The improvement stems from sigmoidbased adaptive blending—transitioning from IBVS (adaptive smoothing factor − 𝛼 = 0 ) under large errors to PBVS (𝛼 > 0.8) near convergence and exponential moving average filtering of control velocities. These results advance adaptive visual servoing for high-precision industrial automation.
2026-02-25
N. P. H. Abeyagunawardana, I. U. Atthanayake, T. M. D. N. Tennekoon
Accurate prediction of the pipe pressure loss is important for engineering applications. But the Reynolds number does not definitively determine whether the flow is laminar or turbulent. Therefore, relying solely on Reynolds number to select the specific equation can be inaccurate, as the actual flow regime might differ from prediction. In this study, computational fluid dynamics (CFD) simulations were conducted using the ANSYS fluent 2023 R2 with the standard k–ε turbulence model and standard wall functions to analyze fully developed pipe flow across Reynolds numbers from 2,000 to 200,000, with varying wall roughness values. A mesh-independence study verified convergence beyond approximately 0.7x106 cells. The investigation systematically varied the inlet velocity and the surface roughness to quantify their effects on pressure loss; this simulated result was compared against theoretical predictions using the Darcy–Weisbach and Colebrook–White equations for transitional and turbulent flow. The findings revealed that CFD consistently predicted below 20% pressure losses in turbulent flow than theoretical models, particularly in the transitional regime where more than 200% difference was observed, highlighting limitations of conventional methods. Pressure loss was found to increase significantly with the inlet velocity, while the surface roughness exhibits comparatively minor influence. These results emphasize the importance of velocity control that minimizes energy loss in piping systems and demonstrate the capability of CFD to provide deep insight into pipe flow.
2026-02-25
M. W. S. B. Piyarathna, P. G. C. R. Gallage, L. K. T. Srimal
Automation of agricultural machines is an essential thing for improving productivity, product quality, and labour efficiency. This study focuses on design, fabrication, and testing an automated bag-feeding unit to enhance the performance of the existing mushroom grow media filling machine. In theindustry, small-scale machines are available for filling mushroom-growing media, but they still require manual labour to load the bags. Throughout this project, we automated that the bag feeding system includes a bag mouth opening system, gripper and moving mechanism, automated bag holder mechanism, PLC (Programmable Logic Controller) control panel, and auxiliary components. A key enhancement is the rack-and-pinion mechanism for bag holder movement and sealing of the mixing chamber for better efficiency. Performance was evaluated by over 50 feeding cycles. The average cycle duration was 73.9 seconds, with a success rate of 84%. Failures were due to conveyor issues (6%), gripper insertion failures (6%), and vacuum bag pickup failures (4%). These results indicate why we need to improve the conveyor and gripper systems in the small-scale mushroom grow media filling machine. PLC-based control and modular automation will improve scalability and adaptability for these kinds of agricultural applications. As future work, we will address failure modes, optimize components, and explore system adaptation for other farming protocols, advancing precision agriculture through cost-effective methods and trying to achieve a fully automated small-scale mushroom-growing media filling machine.