Volume 05 - 2010

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    Simulation of nitrate leaching in Yala season in Batticaloa - A modeling approach
    (University of Kelaniya, 2010) Bawatharani, T.; Mowjood, M.I.M.; Dayawansa, N.D.K.; Kumaragamage, D.
    The leaching behaviour of NO3--N was evaluated through field experiments with those predicted by LEACHM-N, a uni-dimensional, water flow, solute transport and plant uptake model. Therefore, the objective of this study was to evaluate the application of LEACHM-N for predicting nitrate leaching in Batticaloa during Yala 2005. Field experiments were carried out from April 12th 2005 to June 30th 2005. The experimental treatments were 3 nitrogen rates (0, 70 and 140 kg N/ha) together with 3 irrigation rates (7, 14 and 30 mm) which resulted in 9 treatment combinations. The treatments were arranged in a split plot design in 3 replicates. Twenty seven cylindrical lysimeters with 1 m height and 50 cm diameter were built in at the experimental site. Outlets from each lysimeters were fixed with outflow pipes, directed to an underground sampling point, from where the water samples were collected. Red onion (Allium cepa; var. Vethalan) was planted in the lysimeters. Nitrogen fertilizer was applied 3 times during the cropping season. Irrigation water was delivered using a micro sprinkler system. Leachates from individual outlets were collected separately and NO3--N was determined spectrophotometrically by the Cadmium reduction method. A moderately good agreement has been found out in between the measured and the predicted NO3--N losses, but the model overestimated the losses. The treatment combination 140 kg N/ha with 30 mm of irrigation showed better simulation accuracy. It was also found out that the model was unable to predict preferential flow.
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    Liquid junction photocells synthesized with dye coated zinc oxide films
    (University of Kelaniya, 2010) Samarasekara, P.
    Zinc oxide (ZnO) films fabricated using low cost methods were employed to synthesize a liquid junction photocell explained in this report. Methyl violet dye has been coated on ZnO films to enhance the light absorption. The thickness of the ZnO film and the separation between the Platinum electrode and ZnO film were varied in order to obtain the maximum efficiency of the photocell. The best photocurrent and photo-voltage could be measured for ZnO films coated with methyl violet dye for 12 hours. The optimum photocurrent obtained was 0.24 mA/cm2, which was a higher photocurrent for Methyl violet coated ZnO films. But the photo-voltage measured was comparable to the photo-voltage of ZnO films measured by some other researchers. Hence, a considerably higher optimum efficiency such as 2.4% could be obtained for these ZnO films consist of ZnO nanoparticles. The higher effective surface area provided by ZnO nanoparticles is the possible reason for this higher photocurrent.
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    Impact of family income and size on per capita solid waste generation: A case study in Manmunai North Divisional Secretariat Division of Batticaloa
    (University of Kelaniya, 2010) Sivakumar, K.; Sugirtharan, M.
    The generation of solid waste has become an increasing environmental and public health problem everywhere in the world, especially in developing countries. The rate of generation of solid waste in the society is increasing with an increase of population, technological development, and the changes in the life styles of the people. As family size and income are the most significant factors affecting the quantity of solid waste from household consumption, a study on the relationship among these is vital in the decision making on waste management strategies. Therefore, a study was conducted at Manmunai North Divisional Secretariat areas of Batticaloa district to find out the correlation among residential solid waste generation, family size and income. The household sector is one of the primary sources of solid wastes in the study area. This study covered 100 houses with different socioeconomic levels such as income level and family size. There were six components of solid waste; food waste, paper, polyethylene, plastic, glass and metal which were evaluated in this study. Present study revealed that residential solid waste generation showed non-significant positive correlation (r = 0.184, p>0.05) with monthly income whereas significant positive correlation (r = 0.476, p<0.01) was found with the family size. Based on monthly income, generation of food, paper, plastic and glass waste showed non-significant positive correlation while non-significant negative correlation was found with polyethylene waste. Further, residential waste generation such as food, paper, plastic and metal showed significant positive correlation with family size whereas generation of glass and polyethylene waste showed non-significant positive correlation with family size.
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    Effect of moisture stress at different growth stages of tomato plant (Lycopersicon esculentum Mill.) on yield and quality of fruits
    (University of Kelaniya, 2010) Vijitha, R.; Mahendran, S.
    There is a need to utilize the water efficiently and effectively because water availability is scarce in the dry zone of Sri Lanka. An experiment was conducted to determine the changes in fruit quality of tomato cv. KC-1 with moisture stress viz., determine the vitamin C, total soluble solids (TSS) and acid contents of tomato fruits during fruit ripening stage. Also, investigated in the present study was to find out the most critical stage/s of the plant growth to moisture stress in order to sustain the yield by efficient water management. Experiment was conducted at the agronomy farm of the Faculty of Agriculture, Eastern University, Sri Lanka. The experimental design was randomized complete block design with five treatments and four replications. Moisture stress was imposed during vegetative, flowering, early fruiting and fruit ripening stages of tomato for a period of four days in each growth stages. The control plants were watered daily to the field capacity. The stress cycle was single in which water was withheld completely at once. The result showed that moisture stress at fruit ripening stage reduced the vitamin C contents of fruits. The TSS and acid contents of the fruits were slightly affected by moisture stress when the stress was imposed during the fruit ripening stage but they were not significant. Vitamin C, TSS and acid contents of fruits were unaffected by moisture stress given during vegetative, flowering and early fruiting stages. Moisture stress reduced the yield of tomato and the stress during the flowering stage showed the highest yield reduction compared to the other growth stages. Hence, the flowering stage is the most critical stage of growth of tomato to moisture stress for the fruit yield.
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    Strong photoelectron emission from silver nanostructures
    (Journal of Science of the University of Kelaniya Sri Lanka, 2010) Hewageegana, P.
    Localized optically-nonlinear photoelectron emission from metal (silver) nanostructures under two-pulse emission has been developed for relatively low energy. For two-photon emission from random metal nanostructures, it has been shown that the coherent control allows one to move nanosize hot spots whose positions are controllable on a nanometer scale. It is proposed to use silver random planer composite and introduce this photoemission process as an ultrafast process, on femtosecond or subfemtosecond scale.