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
item: Article-Full-text
Why Traffic Signals Fail in Sri Lanka: Reviewing the Realities of Heterogeneous Traffic Dynamics
(The Institution of Engineers Sri Lanka) Salawavidana, SAST; Pasindu, HR; Bandara, JMSJ; Munasinghe, R
Traffic signal design in developing countries frequently underperforms due to the direct application of classical models—Webster's delay formula, HCM, ARR123, and ORN13— developed for homogeneous, lane-disciplined traffic conditions. Sri Lankan intersections exhibit fundamentally different characteristics: heterogeneous vehicle streams comprising motorcycles, threewheelers, non-motorized vehicles, and pedestrians operating without strict lane discipline under geometric constraints. This systematic review synthesizes empirical evidence explaining why conventional signal design methods fail in such contexts. Following PRISMA principles, 138 records were screened, yielding 41 high-quality references spanning foundational theory, classical assumptions, regional adaptations, and Sri Lankan empirical data. The review demonstrates that local intersections systematically violate foundational assumptions regarding lane usage, headway uniformity, start-up behavior, and pedestrian compliance. Observed saturation flows reach 2574 pcu/h/lane—substantially exceeding HCM benchmarks—while behaviors such as motorcycle seepage, lateral filtering, initial surge, and dynamic clustering create discharge patterns that static PCU values cannot capture. A mathematical framework is presented mapping these deviations to quantifiable variables: lateral efficiency, surge discharge dynamics, dynamic vehicle equivalence, headway expansion, and geometric constraints affecting intersection capacity. The paper concludes by proposing context-sensitive design pathways incorporating dynamic PCU factors, behavioral modeling, and simulation-based calibration using SIDRA and SUMO to support locally relevant signal control methodologies..
item: Article-Full-text
Mineralogical Evolution and Geo-mechanical Characterization of Weathering Profiles Along the Central Expressway (CEP 3), Sri Lanka
(The Institution of Engineers Sri Lanka) Sanjeewa, KWD; Nawagamuwa, UP; Abeysinghe, AMKB
This research investigates the mineralogical and geo-mechanical factors influencing slope stability along Section 3 of the Central Expressway Project (CEP 3), Sri Lanka. Through a combination of borehole logging, petrographic analysis, and X-ray diffraction (XRD), a comprehensive weathering profile was established. Results delineate a transition from stable, fresh metamorphic gneissic rocks to highly unstable residual soils (SM and ML types). Petrographic data reveal the progressive alteration of primary minerals, specifically Feldspar, Biotite, and Hornblende, into secondary Clay phases. XRD analysis identified the presence of Smectite and Kaolinite, with the former presenting significant risks for moisture-induced volume changes and rotational slides in high-cut sections. The study concludes that the thickness and stability of the residual mantle are directly governed by the modal mineralogy of the metamorphic parent rock, providing a critical framework for geotechnical risk mitigation in hilly terrains
item: Article-Full-text
Mineralogical Evolution and Geo-mechanical Characterization of Weathering Profiles Along the Central Expressway (CEP 3), Sri Lanka
(The Institution of Engineers Sri Lanka) Nikaweratiya, IPTPDB; Perera, LAHS; Karunadasa, JP; Madawala, RRTWMRAI
Accurate modelling of power system components is essential for reliable power system analysis, particularly in excitation system and AVR studies. While IEEE Std. 421.5–2016 defines how generator saturation factors should be obtained, practical modelling often continues to use standard or factory data, with limited measurement-based updates for aged generators in actual service. This is a key research gap, since saturation characteristics may vary over time due to aging and operating stresses. Accordingly, this study presents the experimental determination of saturation factors of a 20 MW synchronous generator at Sapugaskanda Power Station, Sri Lanka. An open-circuit test was selected because it provides the direct terminal voltage–field current characteristic required for IEEE-based saturation-factor calculation. With the AVR in manual mode, the field current was varied within specified protection limits, and steady-state terminal voltage and field current were recorded using a Hioki data acquisition system and analysed in Excel to construct the open-circuit saturation curve and air-gap line. The saturation factors at 1.0 pu and 1.2 pu were then calculated using the IEEE method. The results provide updated field-based inputs for improved AVR and exciter model accuracy.
item: Book
Fiction wonderland : a comprehensive guide to creating children's fiction books
(2025) Samarawickrama, Sumanthri
Fiction Wonderland: A Comprehensive Guide to Creating Children’s Fiction Books is a research-informed and practice-oriented guide developed to support the creation and publication of quality children’s fiction in Sri Lanka. Grounded in research undertaken through the development of the National Policy for Children’s Books, the book brings together knowledge on child development, inclusive and culturally relevant storytelling, narrative construction, visual development, book design, and publishing practice. It guides authors, illustrators, designers, publishers, educators, and other stakeholders through the interconnected processes of developing children’s fiction—from understanding the child reader and shaping stories to visualising narratives and moving collaboratively from script to publication. The guide translates research and policy principles into practical frameworks, tools, and processes intended to strengthen Sri Lanka’s children’s book ecosystem.
item: Thesis-Abstract
Development of a thermoplastic vulcanizate from natural rubber and polyethylene as a competitive material for roofing sheets
(2026) Wickramaarachchi, WVWH; Walpalage, S; Egodage, SM
In Sri Lanka, roofing materials are commonly manufactured from clay, metal, plastic, wood, and asbestos, each associated with specific limitations. Despite well-documented health risks, asbestos roofing remains widely used due to its low cost. However, extensive scientific evidence linking asbestos exposure to severe health hazards has prompted the Government of Sri Lanka to initiate measures toward banning asbestos-based roofing materials. This has created an urgent need for safer, durable, and cost-effective alternatives. Thermoplastic vulcanizates (TPVs), produced through dynamic vulcanization in which a rubber phase is selectively crosslinked and dispersed within a thermoplastic matrix, offer a promising solution. In this context, the present study focuses on developing a sustainable TPV roofing material using natural rubber (NR) and polyethylene (PE).
Initially, NR/PE blends were prepared via melt blending using a twin-screw extruder with three polyethylene grades, namely low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), at varying compositions to identify the most suitable PE grade for roofing applications. Based on mechanical, physical, and water absorption performance, HDPE was identified as the optimal thermoplastic component. Subsequently, TPVs from NR and HDPE were further optimized by varying blend composition and incorporating particulate fillers to improve performance and reduce cost. Six fillers, including dolomite, calcium carbonate, barium sulfate (BaSO₄), snobrite clay, talc, and kaolin, were evaluated, with BaSO₄ showing the best overall compatibility and reinforcement. Further optimization involved adjusting the loadings of dicumyl peroxide (DCP) as the vulcanizing agent, BaSO₄ filler, and a zirconate coupling agent to enhance interfacial adhesion. Mechanical, thermal, and physical properties were evaluated in accordance with international standards, and morphology was examined using scanning electron microscopy. Prototype roofing sheets (40 cm × 40 cm × 0.6 cm) were fabricated by compression moulding and assessed against relevant PVC-based roofing specifications.
NR/HDPE-based TPVs showed higher tensile strength, tear strength, and hardness than those made with LDPE and LLDPE. Although none reached the 25 MPa tensile strength of commercial PVC-based roofing sheets, all exceeded the 3 MPa minimum required for roofing, with impact strength surpassing that of PVC-based roofing sheets. NR/HDPE-based TPV exhibited the lowest water absorption (0.04%), nearly matching PVC-based roofing sheets and significantly better than asbestos sheets. Based on overall performance, HDPE was identified as the most suitable PE grade for NR/PE roofing applications. The 20/80 (NR/HDPE) composition offers the best balance of mechanical strength and impact resistance, making it ideal for roofing applications. The TPV prepared with BaSO₄ filler demonstrated the highest overall performance, with optimal results observed at a filler loading of 50 phr and 1 phr of DCP. A zirconate loading of 1.5 phr resulted in optimum mechanical properties and refined phase morphology, indicating enhanced interfacial compatibility between the NR and HDPE phases in the TPV. The prototype sheet prepared using the optimized formulation showed comparable impact strength, elongation at break, density, and thermal conductivity to that of conventional PVC-based roofing sheets