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.
 Research Publications |  Thesis & Dissertation |  E- Books |
 UoM Journal Publications |  UoM Conference Proceedings |  Articles published in Scimago's Q1 journals |  UoM Research Reports |  Other Articles authored by UoM staff |
Recent Submissions
item: Thesis-Full-text
Visual composition; evolution of thematic postage stamps as cultural artefacts, reference to Vesak stamps of Sri Lanka
(2024) De Silva, DLNS; Samarawickrama, S
Postage stamps are official documents issued by governments as a part of a communication system, the postal service of the country. Whether attached to an envelope as evidence of postal prepayment, or acquired as a collectable item, postage stamps are primary sources of global material and visual culture. Being a product made by a group of people for intentional communication, a postage stamp can be viewed as an artefact of the culture it was produced. As the World Association for the Development of Philately sees it today, in addition to being a piece of art, and a medium for advertising and promotion, a stamp offers a window into diverse cultures across the world; a calling card from each country. Postage stamps bought, collected and discussed by an estimated 30 million collectors worldwide, are important as revenue raisers. To meet the demands of the global philatelic market, the Philatelic Bureau of Sri Lanka intends to improve the quality and novelty of their stamps, but it is ambiguous what needs to be done. During the long history of philatelic production in Sri Lanka, neither a systematic study analysing the postage stamps as a graphical composition, nor a review of feedback from users/stamp collectors is done. Therefore, time seems fit to reflect on what has been in production, and apply what is learnt, in future work. Based on historical research as a method, this study documents the variations in visual composition on the postage stamps of Sri Lanka, over time. To retain the coherence of the study, it is focused on thematic stamps. The longest continuing sequel of thematic stamps of Sri Lanka is issued commemorating Vesak festival annually. A sample of 28 Vesak commemorative issues accounting for a 100 individual Vesak stamps, issued from 1969-2022 are considered for this study. The visual content on the sample of stamps is analysed in two phases. First, the variation of each visual component on the stamps namely; Name of the country, Denomination, Image, Colour scheme, Typography, Title, Border, Shape, Size and Layout are studied through observational data. Secondly, semiotic meaning-making of the stamps through their function & connection to the world, style, iconic associations, cultural allusions, connection to the social groups, individual experiences of people and additional meanings made in specific contexts are discussed through observational data and qualitative data from interviews with the focus groups made of individuals from the issuing authority, stamp designers, collectors and the general public, incorporating the views of all stakeholders into the study. The findings would present knowledge for visual communication designers and the authorities regulating stamp design programs, which could be referred to when planning the visual content on postage stamps.
item: Thesis-Full-text
Graph neural networks for accelerated 2d truss optimization
(2025) Ariyasinghe, GNC; Herath, S; Mallikarachchi , C; Weeratunga, H
Structural optimization of skeletal forms plays a crucial role in weight-sensitive applications, but conventional iterative methods often demand significant computational effort, especially under varying design parameters and constraints. This dissertation introduces a novel Graph Neural Network (GNN)-based surrogate model designed for real-time structural optimization, offering a computationally efficient alternative. By representing trusses (composed of pin joints and members) as mathematical graphs, where nodes correspond to joints and edges denote member cross-sectional areas, the GNN predicts topology and size-optimized truss structures based on input parameters such as geometry, loading conditions, and boundary constraints. The model eliminates the need for iterative processes by learning from a dataset of problem definitions and their corresponding optimized solutions, significantly reducing computational costs while maintaining high accuracy. Testing across various initial design domains with node configurations of 24, 45, and 60 demonstrated robust per- formance. For topology optimization, the recall rate consistently reached unity or near-unity, and the Jaccard similarity index exceeded 0.95 in all cases with 60 nodes trained on 9600 data points, with minor exceptions of 0.94 and 0.87, still indicating reliable predictions. In size optimization, the Mean Absolute Percentage Error and Symmetric Mean Absolute Percentage Error remained below 8% across all results for cantilever and simply supported loading scenarios. It is important to highlight that these highly accurate optimization results were generated using the GNN-based framework, which reduces the computational time by over 95% compared to traditional optimization methods. These results highlight the model's ability to generalize across diverse design scenarios, enabling rapid, accurate, and material-efficient op- timization. By offering near-optimal solutions with minimal computational effort. this GNN-based approach holds significant potential for sustainable and resource efficient structural design across various applications.
item: Thesis-Abstract
Evaluating the competitiveness of a port for container transshipment operation : a case study of Hambantota Port
(2024) Gunawardhana, JA; Sigera, LCI; Gamage , AIT
The Port of Hambantota is strategically located along the East-West main sea route, with an approximate deviation of ten nautical miles. Most of the current business at the Port of Hambantota relies on automobile roll-on/roll-off, breakbulk, bulk, and project cargo operations. Furthermore, container ship handling operations are also expected to start at the port of Hambantota. Therefore, this study evaluates the competitiveness of the Port of Hambantota as a container transshipment hub in the South Asian region. The study considers both mainline-to-feeder and mainline-to-mainline transshipment operations. The six competing ports that were considered for the study are the Port of Jebel Ali and Port of Salalah in Southwest Asia; the Port of Colombo in South Asia; and the Port of Singapore, Port of Tanjung Pelepas, and Port Klang in Southeast Asia. The competitiveness analysis is based on market share using an extended version of the generalized cost approach combined with a discrete choice model. Senior managers attached to the main container line agency officers in Sri Lanka evaluated the selection criteria for transshipment hub ports and the performance of competing hubs. Further scenario analysis was conducted to understand the potential implications for the transshipment business at the Port of Hambantota. The results indicate that the Port of Singapore has the highest potential to become the market leader in the South Asian region for both types of transshipment operations, despite the presence of the Port of Hambantota. However, the findings also suggest that the Port of Hambantota possesses significant potential for both types of transshipment operations, provided there are continuous improvements in port performance.
item: Thesis-Full-text
Purification of Rutile in Sri Lankan beach sand for the extraction of TIO2 by reducing iron content
(2024) Weerasinghe, WDC; Guluwita, SP; Rohitha, LPS
The Pulmuddai region in Sri Lanka is characterized by key constituents: 55-60% ilmenite, 6-8% rutile, and 5-6% iron. Iron's presence emerges as a critical impurity necessitating pre-extraction removal for titanium dioxide extraction from rutile. Attaining a TiO2 purity exceeding 99% within rutile is attainable through targeted iron elimination and meticulous optimization of the purification process. The methodological approach commences with the initial screening and separation of beach sand, utilizing the Humphrey spiral technique to selectively isolate high-density minerals enriched with rutile and ilmenite. Subsequent separation of rutile from ilmenite employs a magnetic separator. The conclusive step involves the strategic removal of iron from rutile via leaching with hydrochloric acid (HCl). Optimization of leaching parameters, including the solid-to-liquid ratio (S/L ratio), HCl concentration, and reaction time, maximizes iron removal from rutile. A comprehensive analysis of samples before and after leaching employs a UV-visible spectrophotometer and scanning electron microscopy utilizing Energy Dispersive X-Ray Spectroscopy on the samples. Results indicate 83.3% reduction in iron content within rutile from the initial raw mineral, achieved under optimized conditions of 1:3 S/L ratio, 80°C, 4-hour reaction time, and 4M HCl concentration.
item: Thesis-Full-text
Establishing BIM framework for Integrating passive design strategies for designing energy-efficient residential high-rise buildings in Sri Lanka
(2024) Perera, PWUS; Lewangamage, CS; Weerasuriya, AU; Ruparathna, R
Sri Lanka expects a surge in demand for residential high-rise buildings (RHBs). Energy-intensive heating, ventilation, and air conditioning (HVAC) systems are relied on for the indoor thermal comfort of these buildings. The HVAC dependency can be minimized by integrating Passive Design Strategies (PDS) that leverage natural resources to control heat transfer and ventilation. Despite their potential, the efficacy of PDS is sparsely studied for Sri Lankan buildings. Addressing this knowledge gap, this study introduces a novel Building Information Modeling (BIM)-based Building Performance Analysis (BPA) framework for an energy-efficient building design workflow. Eight popular PDS were identified through a questionnaire survey among local building designers. These strategies were then applied to a typical RHB in three distinct sub-climates in Sri Lanka. The comparison between the survey findings and simulation results highlights a discrepancy between the popularity of PDS and their actual performance, emphasizing the need for enhanced awareness among Sri Lankan building designers. The local and global sensitivity analyses revealed low e-coating glasses and solar reflective wall paints as the energy-efficient PDS for Colombo and Kandy. In contrast, low conductivity walls and multiple/thick glazing are the most effective PDS for Nuwara Eliya. The multi-objective optimization of this study demonstrated that the optimum PDS design could substantially reduce operational energy consumption by 41.4%, 61%, and 29.4% and investment costs by 7.5%, 4%, and 4% compared to original designs in Colombo, Kandy, and Nuwara Eliya. Importantly, prioritizing low operational energy PDS design over the investment cost proves crucial for achieving sustainable metrics, such as carbon emission reduction and green rating scores. While the output of this study sets basic guidelines for Sri Lankan building designers in integrating passive design strategies for RHBs, the novel BIM-based BPA framework stands as a solution for existing technical gaps in BIMbased building design workflows.