Browsing by Author "Gamachchige, N.T.S.G."

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    Algorithmic Aspects of Trees in Graph Theory: Identification and Application
    (Uva Wellassa University of Srilanka, 2011) Gamachchige, N.T.S.G.; Udagedara, D.T.
    Note: See the PDF Version With the rapid advances of the computer technology, Mathematics and Computer Science have developed into two entirely separate disciplines. Since graphical approach lend themselves naturally as model for a variety of situations, including the hardware of computer and certain aspects of computer software, Graph Theory plays an increasingly important role within Computer Science. In the study of graphs, it soon becomes evident that efficient algorithms are necessary for solving problems of any significant magnitude. It has become fashionable to mention that there are applications of Graph Theory to some areas of Physics, Chemistry, Computer technology, Electrical and civil engineering, Sociology and Economics. Computers have made our daily activities easier with fast and highly accurate outcome. Since we find the applications of Graph Theory in almost all areas, using the computer to solve practical problems makes our task easy. Transforming of our problems into a form that can be understood by the computer is the task of a computer language. Algorithms are used for that purpose. This research consists of Algorithmic aspect of Trees in Graph Theory and is designed to emphasize the close tie between the theoretical and algorithmic aspect of Trees in Graph Theory. Rather than employing a specific computer language for presenting algorithms, the steps were used that are common to many languages. This research has introduced few algorithms, based on properties of Trees in Graph Theory, for practical problems which we often come across. A complexity analysis is also given for each algorithm. The main objective is to recognize the algorithms to solve real world problems using the properties of Trees in Graph Theory and the other objective is to apply these algorithms to solve some problems in day to day life.
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    Saltwater Intrusion into Freshwater Lagoons in Jaffna Peninsula
    (Uva Wellassa University of Sri Lanka, 2019-02) Gajenthiran, A.; Udagedara, D.T.; Gamachchige, N.T.S.G.
    Surface water and groundwater are scares and hence highly demanded resources in the Jaffna peninsula causing the communal water supply is an extreme challenge. In order to ease the burden, barrages were constructed closing fresh water lagoon envisaging the accumulation of rainwater during the monsoon periods. Though the initial expectation was the lagoons to act as freshwater ponds, due to malfunctioning of barrages the anticipation wilted. The barrages were reconstructed expecting the same purpose early this decade. However, the salinity has been unexpectedly high even since then irrespective to the climatic patters viz dry and wet seasons in the peninsula. This research focuses on understanding the behaviour of salinity variation in the Upparu lagoon and in the Thondamanaru lagoon which is under the spot light nowadays. Several investigations of the salinity variations across the Upparu barrage showed that there are subsurface linkages with high saline water from the Jaffna lagoon. In addition to that, the evaporation during dry season increases the salinity away from the barrage toward the mainland. The electrical conductivity (EC), salinity, sodium and chloride concentrations were measured in 58 groundwater wells around the lagoon as the lagoon water recharge the nearby groundwater table. The EC varies between 954 µS cm-1 to 13450 µS cm-1 in the wet season and it is between 673 µS cm-1 to 18570 µS cm-1 during the dry season. The salinity varies from 0.63 to 10.32 in the wet season, where as it is 0.92 to 12.3 in the Dry season. Chloride concentrations vary between 49.70 mg L-1 and 3012 mg L-1 in wet season and between 33.5 mg L-1 and 5538 mg L-1 in dry season. Sodium concentrations vary between 43.1 mg L-1 and 5324.3 mg L-1 in wet season and between 17 mg L-1 and 4124 mg L-1 in dry season. The groundwater quality far from the barrage is comparatively good to the areas closer to the barrage. This observation has been appearing with promising prospectus over last six years. Yet, it is not convinced whether this is due to the less effectiveness of the barrage or subsurface movement of brackish water from the Jaffna lagoon to the south Kopai area. Additionally, the dry period of this year was longer than usual. Thus, it is recommended to continue the research focusing more on south Kopai area.