Research Publications Authored by SLIIT Staff

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This collection includes all SLIIT staff publications presented at external conferences and published in external journals. The materials are organized by faculty to facilitate easy retrieval.

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    PublicationOpen Access
    Effect of hot ethral-dip treatment for improving peel colour development and reducing stem-endrot of ‘Karuthacolomban’mango
    (Sri Lanka Department of Agriculture, 2004) Sarananda, K. H; Wijesinghe, W. A. J. P; Dulani, H. N; Peiris, C. N
    Poor colour development of the peel and high incidence of stem-end-rot development are the major reasons for excessive postharvest losses in mango, variety” Karuthacolomban ‘. Experiments were conducted to investigate the effect of artificial ripening by application of ethral at ambient (26ºC), 48º and 52ºC on reducing postharvest losses. Time taken for ripening was shortened when the treated temperature was increased. Peel colour development was improved when fruits were treated at 52 C. Total soluble solids and titratable acidity of induced fruits remained similar to those of control at table ripe stage. No difference observed in the sensory evaluation of ripe mango indicated that the taste, smell and flavour were not affected by the application of ethral. Fruits inoculated with Lasiodiplodia theobromae showed less severity of stem-endrot when those fruits were induced for ripening at 52 C with ethral. When inoculated fruits were allowed to ripen naturally a high disease severity was observed. Therefore, after harvesting, mature” Karuthacolomban ‘mangoes could be treated with hot ethral (1 ml/l H2O) at 52 C for 3 minutes to induce ripening resulting in an attractive peel colour and a low severity of stem-end-rot.
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    PublicationOpen Access
    Entrance zone effect on the sediment trapping efficiency in desilting tanks of run-of-river type mini-hydropower plants
    (The University of Peradeniya, Peradeniya, Sri Lanka, 2007-11-30) Rathnayake, U. S; Harishchandra, M. R. T. S; Weerakoon, S. B
    Development of run-of-river type minihydropower plants is receiving increased attention in Sri Lanka at present owing to the incentives announced for developers of renewable power generation projects during the last decade by the Sri Lankan government. The sources for most of the run-of-river type mini hydropower plants are mountainous streams where the discharges experience significant seasonal variation with frequent flash floods. The catchments of these streams are generally steep and face an increasing trend of soil erosion due to cultivation and other human activities. Therefore, the stream flows carry high sediment loads during seasonal floods. This sediment-laden flow enters the headrace canals feeding water to the turbines of the rninhydropower plants. Sediment in the water passing through the turbines with high velocity erode the contact surfaces of turbine components. The erosion of turbine components leads to a drop in hydraulic efficiency and to a high maintenance cost of the turbines. Removal of sand carried with the flow in the headrace canals of run-of-river mini hydropower plants is therefore an important issue for the developers to reduce the maintenance cost of the turbines (Singal and Ranendra, 2006). Introduction of a de-silting tank in series with the headrace canal is one of the commonly used techniques for this purpose. De-silting tanks are designed as settling basins to settle sediment greater than a targeted size (Janssen, 2004). The shape and the size of the de-silting tank are major factors affecting the sand trapping efficiency of the desilting tank. Several empirical and semiempirical relations for the efficiency of …
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    PublicationOpen Access
    Effect of the entrance zone on the trapping efficiency of desilting tanks in run-of-river hydropower plants
    (Department of Civil Engineering, University of Peradeniya, Peradeniya, 2007-10-22) Weerakoon, S. B; Rathnayake, U. S
    Run-of-river mini hydropower plants are generally installed in mountainous streams where the catchments are generally steep and vulnerable to high soil erosion. Seasonal heavy rains, especially in tropics and monsoon regions produce large sediment yield from these catchments and the streams experience high sediment concentrations during seasonal floods. Therefore, removal of sand entering into headrace canal in run-of-river mini hydropower plants is an important issue in the run-f-river mini hydropower schemes to reduce the erosion of turbines and other components in contact with water. The desilting tanks constructed in series with the headrace canal play an important role here. The shape and the size of the desilting tank are major factors on the sand trapping efficiency of it. This paper presents a series of laboratory experiments carried out to investigate the effect of the entrance zone on the sand trapping efficiency of the desilting tanks using a scale model of a desilting tank with varying entrance expansion angles. The sand trapping efficiency is found to vary from 50% to 85% with the reduction of espansion angle from 30o to 10o .
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    PublicationEmbargo
    Effect of point defect injection on diffusion of boron in silicon and silicon–germanium in the presence of carbon
    (American Institute of Physics, 2005-06-01) Karunaratne, M. S. A; Willoughby, A F W; Bonar, J M; Zhang, J; Ashburn, P
    Boron diffusion in Si and strained SiGe with and without C was studied using point defect injection. Interstitial-, vacancy- and noninjection conditions were achieved by annealing Si capping layers which were either bare, with Si3N4 film or with Si3N4+SiO2 bilayers, respectively. Concentration profiles of B, Ge, and C were obtained using secondary-ion-mass spectrometry and diffusion coefficients of B in each type of matrix were extracted by computer simulation. Under inert annealing, we find that C strongly suppresses B diffusion in SiGe:C, but the effect of C is less strong in Si:C, particularly at high temperatures. In contrast, C only weakly suppresses B diffusion in both Si:C and SiGe:C under interstitial injection. For inert anneal conditions, C reduces the B diffusion coefficient in Si:C by factors of 4.2, 5.9, and 1.9 at 940, 1000, and 1050 °C respectively, whereas for interstitial injection the factors are 2.1, 1.3, and 1.1, respectively. The equivalent factors for SiGe:C are 8.4, 5.9, and 8.0 for inert anneal conditions and 2.2, 3.4, and 1.6 for interstitial injection conditions. The degree of B diffusion suppression achieved in both Si:C and SiGe:C is dependent on the level of C retained during annealing. Diffusion of C is shown to be faster in Si:C and hence less C is retained there after annealing than in SiGe:C. Interstitial injection is shown to strongly enhance C diffusion in both Si:C and SiGe:C and hence decreases the effectiveness of C for B diffusion suppression. These findings illustrate that the retarding effect of C on B diffusion in both Si:C and SiGe:C is strongly reduced when the anneal is carried out under conditions where interstitials are injected from the surface.