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Browsing by Author "Kulatunga, D. D. S."

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    Adaptive green time allocation method for traffic congestion based on cell transmission model and genetic algorithm
    (Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Priyasad, H. A. D.; Kulatunga, D. D. S.
    Traffic congestion is defined as a physical phenomenon relating to the manner in which vehicles impede each other’s progression as demand for limited road space approaches full capacity. This makes trip time longer and increasing queuing. Also it causes serious problems for the day to day lives of people, massive financial and man-hour loss, environment pollution, some diseases etc. In Sri Lanka, traffic congestion in a given area occurs for many reasons. The main reason is that the demand of road does not match to road capacity. In Sri Lanka, although an increase of 10% per year road demand is expected, it can increase road capacity by around 2% to 3% per year. Other important reasons are the existing traffic control system and traffic intersections. Traffic control systems play a central role of traffic management in Sri Lankan cities. Existing traffic light system mainly controls the traffic light change in constant cycle time. But road conditions in a given area vary day by day. If the traffic control system does not deal with these variations, then traffic control system will create bottlenecks and delays. Therefore, the control of traffic requires adequate adjustments to these variations. This research focused on studying and applying cell transmission model to dynamic traffic signal controlling procedure. Basic cell transmission model is used to model the dynamic changes of vehicular traffic flow and to estimate the total delay of vehicles in a given region within a given time interval under different green time allocations. To find an optimal signal timing plan, the Genetic Algorithm is used. The proposed model is applied with certain assumptions to find an optimal time plan to a signalized intersection in main Kandy - Colombo road which has heavy traffic congestion in the morning hours in weekdays. A section of this region is selected to minimize the total delay and to find an optimal dynamic time plan for the signal lights analyzing the actual data collected in this region using four video cameras. The results are compared with the existing pre-timed signal time plan and the corresponding total delay. It is observed that the proposed dynamic signal timing plan will reduce average delay by 6.2675% and it can be proposed as an alternative for the existing system.
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    Economic determinants of suicides in Sri Lanka over the period 1975 – 2015.
    (International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Devindi, R. P. D. C. S.; Kulatunga, D. D. S.
    Suicide is a major public health problem in the world. According to the World Health Organization, every 40 seconds, a person commits suicide somewhere in the world. In Sri Lanka a steady increase of suicides has been reported and it stands in the fourth place among the countries with high occurrences of suicides in 2015. Further suicide is one of the major causes of death in Sri Lanka. There are many studies done in Sri Lanka to investigate the variations in suicide rates in relation to age, gender, method and reason specific trends and geographical distributions. But there are no previous studies done to identify the economic determinants using a dynamic econometric model of suicides on the basis of time series data. This study investigates the association of economic conditions with the suicide rates among male, female and general population in Sri Lanka over the period 1975-2015.The data for suicides from 1975 to 2015 was taken from the Registrar General Department and Police Department of Sri Lanka. The effective suicide rates were computed as the number of suicides per 100,000 population. The unemployment rate, GDP growth rate, inflation and fertility rates for 1975-2015 were taken from the Department of Census and Statistics. In our analysis, overall suicide rate, male suicide rate and female suicide rate are taken as dependent variables, and unemployment rate, GDP growth rate, inflation and fertility rate as independent variables in each case. Because of the time series nature of the variables, Autoregressive Distributed Lag (ARDL) regression model is employed to identify the long run relationship between the dependent variable and explanatory variables. The analysis reveals that, for the general population the incidence and rate of suicide increase with the increase in unemployment rate and inflation. Further, the male suicide rate increases with the increase in unemployment and inflation. The positive coefficient of the unemployment rate supports the increase in female suicides. In general, the ARDL models reveal the association between suicide and three economic variables; inflation, unemployment and GDP growth. The inflation and unemployment enhance the incidence of overall suicides and male suicides, while only inflation supports the incidence of female suicides in the long run in Sri Lanka. There are some limitations in the analysis due to the unavailability of information of several economic factors. The results obtained in this analysis would be helpful for a comprehensive work on economic determinants of suicides in Sri Lanka.

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