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U n i v e r s i t y of P e r a d e n i y a

The Institutional Repository of the University of Peradeniya is the University's digital gateway to scholarly knowledge and research excellence. Established as the next phase of the Digital Library initiative launched by the University Library in 2011, it preserves, showcases, and provides open access to the intellectual output of the University community.

Through a rich collection of research articles, conference proceedings, theses, dissertations, and other scholarly works, the repository enhances the visibility, accessibility, and long-term preservation of knowledge, extending the global reach and impact of the University of Peradeniya’s academic and research contributions.

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Recent Submissions

Application of the coupled energy simulation and computational fluid dynamics approach for predicting energy performance of buildings
(University of Peradeniya, Sri Lanka, 2015-11-06) Bandara,R.M.P.S.; Attalage,R.A.
Buildings account for nearly 40% of the global energy consumption and hence presently high emphasize is placed on improving the energy performance of buildings. Energy Simulation (ES) is the most popular approach in predicting the energy performance of buildings during their conceptual design stage. However, it is observed that this methodology shows certain inherent deficiencies in predicting the energy performance of buildings. Energy Simulation tools do not have the capacity to model air circulation through the building space explicitly. ES tools mainly rely on the simplifying assumption that air within a thermal zone of a building is well-mixed. Furthermore, convective heat transfer coefficients of building surfaces are calculated using set empirical correlations. Literature also reveals that most Energy Simulation tools under-predict energy consumption in buildings, especially under sunny conditions. On the other hand, Computational Fluid Dynamics (CFD) tools can predict airflow field, velocities, relative humidity and contaminant concentrations within an occupied space of a building extensively and accurately. Also, they are capable of determining the temperature distribution within the building space and convective heat transfer coefficients of the building envelope. However, CFD simulations need to be provided with the corresponding boundary conditions of the computational domain, which are readily available in the Energy Simulation approach. On this basis, the paper explains how Energy Simulation can be coupled with Computational Fluid Dynamics in predicting the energy performance of a building more accurately through complementary data exchange between the tools. The office building considered in the study is to be constructed in the suburbs of Colombo. The analysis uses ENERGYPLUS 8.0 and ANSYS FLUENT 6.3 as the tools for conducting Energy Simulation and Computational Fluid Dynamics respectively. MATLAB R2012a establishes the coupling platform. The study shows that the coupled approach predicts considerably higher energy consumption for the building compared to that given by conventional Energy Simulation using ENERGYPLUS.
Runoff model development for Nilambe catchment in Sri lanka using hec-hms
(University of Peradeniya, Sri Lanka, 2015-11-06) Priyankara,W.M.S.; Weerakoon,S.B; Nandalal, K.D.W.
Assessment of catchment runoff plays a vital role in catchment management. Hydrologic models are used as tools to simulate hydrologic processes and estimate catchment runoff parameters. But it is a challenging task to calibrate such models to represent real situation due to the limited data availability. In this study, Hydrologic Modeling System (HEC-HMS), developed by the Hydrologic Engineering Center, USA has been used to set up run off simulation model for the Nilambe catchment of the Mahaweli River located upstream of Polgolla reservoir in Sri Lanka. The Nilambe catchment was selected due to its importance to hydropower generation by Nilambe Hydropower Plant installed utilizing the runoff of the catchment. The Nilambe catchment was divided into 17 sub-catchments considering the hill-slopes and stream network. Clark unit hydrograph was selected as transport method with relevant time of concentration values for sub-catchments. Initial and constant loss method was used for flow calculation and constant loss value and imperviousness were used as calibration parameters. Recession base flow method with ratio to peak threshold method was selected to calculate base flow. The model was calibrated for a period of one year from 01 April 1992 to 30 March 1993. The validation of the model was carried out for the period from 01 November 1993 to 31 October 1994. Calibrated model suggests a constant loss rate of 5 mm/h and percentage imperviousness of 28% for the initial and constant loss method. The recession constant of 0.98 and the peak to ratio of 0.18 of the threshold method was used. The calibrated model is a useful tool for water resources development planning in the Nilambe catchment or similar hilly catchment in the Mahaweli basin. The model was used to generate daily runoff of the Nilambe catchment for 20 years period from 1976 to 1996, and the flow duration curve was developed. It is found that the energy output from the Nilambe hydropower plant can be increased by about 18% with a Plant factor of 30% by increasing the design discharge to 6.3 m3/s from present 3.6 m3/s.
Effect of dietary supplementation of yeast fractions (Safmannan®) on growth performance and nutrient digestibility in broiler chickens fed adulterated rice bran
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Samarakoon, S. M. R.; Vidanapathirana, V. S. A.; Jayawardana, B. C.; Karunaratne, N. D.; Munasinghe, V.; Weththasinghe, P.
This study investigated the effects of dietary supplementation of yeast fractions (Safmannan®) on growth performance and nutrient digestibility in broiler chickens fed rice bran adulterated with paddy husk. A total of 96 one-day-old Cobb 500 broiler chicks were randomly allocated to four treatment groups (n = 4 replicates, 6 birds per replicate) and fed one of four isonitrogenous and isoenergetic diets: T1 – corn-soybean-based control diet, T2 – control diet + 0.05% Safmannan®, T3 – control diet + paddy husk adulterated rice bran, and T4 – control diet + paddy husk adulterated rice bran + 0.05% Safmannan®. Growth performance was assessed weekly, and ileal nutrient digestibility was evaluated on day 33. At the end of the 35-day feeding period, carcass yield, breast muscle yield, and weights and lengths of digestive organs were measured. Dietary supplementation with 0.05% Safmannan® (T2) increased (P < 0.05) the final body weight (1691 g per bird), weight gain (1651 g per bird), and improved the feed conversion ratio (1.36 g/g). Inclusion of paddy husk adulterated rice bran (T3) reduced (P < 0.05) the growth performance, while the combination of Safmannan® with paddy husk (T4) showed partial recovery. Safmannan® supplementation also improved (P < 0.05) the carcass yield (72%), breast muscle percentage (32%), and digestive organ development when fed paddy husk adulterated diets. Apparent ileal dry matter digestibility was higher (P < 0.0001) in T2 (82%), with the lowest values observed in T3 (75%). Safmannan® supplementation enhanced growth performance and nutrient digestibility, while mitigating the adverse effects of adulterated rice bran in broiler diets.
Factors contributing to the adoption of recommended dairy management practices among small-scale dairy farmers in Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Gunarathna, S.; Shah, J. A.; Buda, M.; Kaka, U.; Dissanayeke, U.
Sri Lanka continues to face a shortfall in dairy production, despite its high livestock production potential. Understanding the production environment of dairy farmers, is essential for enhancing productivity . Therefore, this study was designed to identify factors contributing to the adoption of recommended management practices. The study employed a cross-sectional research design and a quantitative research method. The study was conducted in the Central Province and utilized a questionnaire as the research instrument. A total of 393 small-scale dairy farmers were selected using a multistage sampling method. Adoption of Recommended Management Practices was assessed, based on breeding and reproductive management, feed and fodder management, and clean milk production. The conceptual model was developed by integrating the Unified Theory of Acceptance and Use of Technology, the Theory of Planned Behavior, and the data, information, knowledge, and wisdom framework. Data were collected on demographics of dairy farmers, knowledge, attitude, performance expectancy, effort expectancy, social influences, facilitation conditions, voluntariness, intention to adopt, and adoption of recommended management practices. Partial Least Squares Structural Equation Modeling was employed to analyze the structural relationships between multiple variables. Results revealed that knowledge, effort expectancy, social influence, facilitating conditions, voluntariness, and adoption intention significantly contribute to the adoption of recommended dairy management practices. These findings highlight the need of government interventions to enhance facilitating conditions and leverage social influence for improving national dairy productivity.
Paddy husk adulterated rice bran in broiler diets: impact on growth performance, nutrient digestibility and gut health
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Samarakoon, S. M. R.; Konthasinghe, K. H. M. N. B.; Weththasinghe, P.; Karunaratne, N. D.; Jayawardan, B. C.
This study evaluated the impact of dietary inclusion of paddy husk-adulterated rice bran on growth performance, nutrient digestibility, and the occurrence of intestinal lesions in broiler chicken. Five isoenergetic and isonitrogenous diets were formulated: a corn-soy-based control diet containing unadulterated rice bran and four diets containing rice bran adulterated with paddy husk at 3% (3PH), 5% (5PH), 8% (8PH) and 10% (10PH). One hundred and twenty Cobb 500, one-day old chicks were randomly fed with one of the five experimental diets (n=4 and 6 birds per replicate). The birds were provided with ad libitum water and feed for 35 days. Growth performance, relative organ weights and lengths, ileal dry matter digestibility and occurrence of small intestine lesions of the birds were assessed. Body weight gain (1483-1710 g per bird), feed intake (3137-3210 g per bird), and feed conversion ratio (1.86-2.19 g/g), showed no significant differences among dietary groups (P>0.05). Apparent ileal dry matter digestibility was also not significantly affected by the diets (P>0.05). Carcass yield and breast muscle yield remained unaffected, though gizzard and caecum weights were higher (P<0.05) in birds fed 8PH compared to those fed control diet, suggesting enhanced digestive function. Notably, birds fed 3PH reduced duodenal lesion odds (OR = 0.020, P<0.05), indicating a protective effect on gut integrity, while higher levels (5PH, 8PH and 10PH) showed no impact on intestinal lesions (P>0.05). In conclusion, rice bran adulterated with up to 10% paddy husk can be included in broiler diets without impairing growth performance or nutrient digestibility.