University of Peradeniya

About: University of Peradeniya is a education organization based out in Kandy, Sri Lanka. It is known for research contribution in the topics: Population & Poison control. The organization has 5970 authors who have published 7388 publications receiving 197002 citations.

Monitoring rainfall trends to predict adverse impacts—a case study from Sri Lanka (1964–1993)

Abstract: This paper describes an analysis of long-term rainfall trends in central mountainous region of Sri Lanka. A 30-year 60 rain gauge data set is analyzed to identify the trends in annual and seasonal rainfall. Inter-annual as well as intra-annual rainfall trends are investigated to understand the adverse impacts on water resources, floods and land degradation. It is found that there is a decrease in the annual rainfall in the region, while different seasons show mixed results. The March–April 1st inter-monsoon period shows the highest decrease in rainfall where almost all the rain gauges have recorded decreasing rainfall. In addition to the decreasing rainfall trend, the numbers of rainy days have reduced giving rise to an increasing rain intensity trend. In order to understand better the changes to rain intensity-frequency relation, a universal multifractal analysis was carried out where multifractal models calibrated to first and last decades of the rain series are used to estimate the intensity–frequency relations in the rainfall series. The results show that there is a decrease of inter-monsoon rainfall, while the intensities and return period of extreme events appear to become shorter. These changes could be associated with regional climate changes, and are consistent with projections related to Asia Brown Cloud phenomena.

Conditioning technique for multiinput-multioutput processes with input saturation

Abstract: The problems of controller windup and directional change in controls, in controllers for multiinput multioutput processes with input saturation, is considered. To avoid the windup problem, a generalisation is proposed for the conditioning technique based antiwindup compensator, by introducing a filtered setpoint. This provides a parameterisation to deal with situations where the original conditioning technique was not suitable. To reduce the effect of directional change in controls due to the multiple saturation, further modifications to the conditioning technique are proposed. An interesting outcome is that the generalised antiwindup compensator due to Astrom and Wittenmark is interpreted in terms of the conditioning technique; moreover, these interpretations are used to introduce modifications to their scheme in order to deal with the problem of directional change in controls.

Resolving conflicts in water sharing: A systemic approach

Abstract: [1] With industrial development and economic growth, conflicts over use and allocation of water have been increasing. Though diverse efforts have been made toward resolving conflicts through computer-based models, its clear understanding is prerequisite for models to be effective. A systems view illuminates how people think and consequences of their thoughts and actions on results and thus helps to achieve sustainable solutions. This paper presents a systemic approach to assist stakeholders in two different jurisdictions in a hypothetical water resource system to resolve a potential water-sharing conflict. A causal loop diagram developed provides an understanding of the conflict dynamics and feedback nature. A system dynamics simulation model developed fitting the causal diagram offers a significant opportunity to explore conflict's behavior and resolution with respect to final water allocations and time necessary to reach an agreement. The impact of initial aspiration, influence on system and struggle of stakeholders is discussed in detail.

Arsenic, cadmium, lead, and chromium in well water, rice, and human urine in Sri Lanka in relation to chronic kidney disease of unknown etiology.

Abstract: Chronic kidney disease of unknown etiology (CKDu) is spreading gradually in Sri Lanka. In the current research, 1,435 well water samples from all 25 districts of Sri Lanka, 91 rice samples, and 84 human urine samples from both CKDu-endemic and non-endemic areas in Sri Lanka were analyzed for arsenic, cadmium, lead, and chromium to detect whether toxic elements could be a cause of CKDu. The liver-type fatty acid binding protein (L-FABP) concentration and arsenic, cadmium, lead, and chromium concentrations of the urine samples were analyzed to determine the relation of L-FABP with arsenic, cadmium, lead, and chromium. High concentrations of arsenic, cadmium, lead, and chromium were not detected in the well water samples from CKDu-endemic areas. Arsenic, cadmium, and lead contents in the rice samples from both CKDu-endemic and non-endemic areas were well below the Codex standard. There were no relationships between the L-FABP concentration and concentrations of arsenic, cadmium, lead, and chromium in urine. In addition, arsenic, cadmium, lead, and chromium concentrations in human urine samples from CKDu-endemic areas were not significantly different from those from non-endemic areas. These findings indicated that arsenic, cadmium, lead, and chromium could not cause CKDu.