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Monitoring Water Resources over the Kotmale Reservoir in Sri Lanka Using ENSO Phases
Chandrasekara, Sewwandhi,Prasanna, Venkatraman,Kwon, Hyun-Han Hindawi Limited 2017 Advances in meteorology Vol.2017 No.-
<P>In this study, the El Nino Southern Oscillation (ENSO) phase index is used for water management over the Kotmale reservoir in Sri Lanka. Daily rainfall data of 9 stations over the Kotmale catchment during 1960–2005 June-September (JJAS) season is investigated over the Kotmale catchment. The ENSO phases are identified based on the 0.5°C sea surface temperature (SST) anomaly over Nino 3 region. The study has brought out few stations showing increasing and a few decreasing seasonal rainfall trends for JJAS season, while there is no change in the annual rainfall for the catchment. Monthly and seasonal rainfall of all the selected stations showed negative correlation with the sea surface temperature (SST) over the Nino-3 region index during JJAS season with varying magnitudes. During the warm phase of ENSO, below average rainfall is prominent for JJAS season over many stations. The rainfall especially during early September showed a significant below average rainfall during the warm ENSO phase. The seasonal rainfall during neutral and cold ENSO phases does not experience similar significant changes as seen during warm ENSO phase. Inflow of the Kotmale reservoir shows decreasing trend for the period of 1960–2005 in the observation from all stations collectively.</P>
Using RuO2 anode for chlorine dioxide production in an un-divided electrochemical cell
Chandrasekara Pillai, K.,Kwon, Tae Ok,Park, Bo Bae,Moon, Il Shik IWA Publishing 2010 Water Science & Technology Vol.61 No.8
<P>Chlorine dioxide is a well known powerful disinfectant. Although there are several chemical and electrochemical methods developed for on-line chlorine dioxide generation, the details are mostly confined as patents. We studied in this work the electrochemical generation of dissolved chlorine dioxide from an un-buffered solution of sodium chlorite and sodium chloride mixture in an un-divided electrochemical cell set-up with RuO2-coated-Ti anode and Pt-coated-Ti cathode under constant current mode. Various process parameters including feed flow rate (10 to 150 ml/min), feed solution pH (2.3 to 9.4), concentration of sodium chloride (0 to 170 mM), concentration of sodium chlorite (0 to 7.7 mM), and the applied current (100 to 1,200 mA) were optimized. Experiments were conducted by performing single pass experiments, with no circulation. The current efficiency and the power consumption were calculated for the optimized conditions, and compared with IrO2 electrode of our previous investigation.</P>
Chandrasekara Pillai, K.,Raju, T.,Chung, Sang Joon,Moon, Il-Shik John Wiley Sons, Ltd. 2009 Journal of chemical technology and biotechnology Vol.84 No.3
<P>BACKGROUND: Hydrogen sulfide (H<SUB>2</SUB>S) from industrial activities and anaerobic manure decomposition in commercial livestock animal operations is an offensive malodorous and toxic gas even in small concentrations, causing serious discomfort and health and social problems. The objective of this study was to employ for the first time a novel, attractive, low cost, environmentally benign mediated electrochemical oxidation (MEO) process with Ce(IV) as the redox catalyst for H<SUB>2</SUB>S gas removal from an H<SUB>2</SUB>S–air feed mixture.</P><P>RESULTS: The influence of liquid flow rate (Q<SUB>L</SUB>) from 2–4 L min<SUP>−1</SUP>, gas flow rate (Q<SUB>G</SUB>) from 30–70 L min<SUP>−1</SUP>, H<SUB>2</SUB>S concentration in the H<SUB>2</SUB>S–air feed mixture from 5–15 ppm, and Ce(III) pre-mediator concentration in the electrochemical cell from 0.1–1 mol L<SUP>−1</SUP> on H<SUB>2</SUB>S removal efficiency were investigated. Both liquid and gas flow rates influenced the removal efficiencies, but in opposite directions. Nearly 98% H<SUB>2</SUB>S removal was achieved when the concentration of Ce(IV) mediator ion in the flowing scrubbing liquid reached 0.08 mol L<SUP>−1</SUP>.</P><P>CONCLUSIONS: The new MEO method proved promising for H<SUB>2</SUB>S removal, achieving high removal efficiency. Integration of the electrochemical cell with the scrubber set-up ensured continuous regeneration of the mediator and its repeated reuse for H<SUB>2</SUB>S removal, avoiding use of additional chemicals. Since the process works at room temperature and atmospheric pressure utilizing conventional transition metal oxide electrodes more commonly used in industrial applications, it is also safe and economical. Copyright © 2008 Society of Chemical Industry</P>
Landmarks based route planning and linear path generation for mobile navigation applications
Pasindu Chandrasekara,Thejaka Mahaulpatha,Dananjaya Thathsara,Irendra Koswatta,Nimalika Fernando 대한공간정보학회 2016 Spatial Information Research Vol.24 No.3
In this study a landmarks based navigation model considering local context is designed and a proto- type is implemented. A route planning model where both the distance of a route and the strength of landmarks along the route are considered when deciding the optimum route to follow is developed. The Dijkstra algorithm is used as the basis and if the route is having more strength related to landmarks, it is prioritize while comparing with the dis- tance. The route’s strength is defined based on number of landmarks visible along it and their salience. The hori- zontal spread, the height and the visibility of landmarks at different time of the day and the social/cultural significance are considered as attributes which give strength to a land- mark. To utilize the mobile screen in effective manner, a map generalization is used to show the optimum path. With landmarks the map becomes congested and difficult to read on mobile screen. Therefore the path is reduced to a linear map which shows the path reducing curves while empha- sizing the turns. Douglas–Peucker algorithm is used to derive the linear path. The linear map, which is a schematic representation of the actual map, reduces the path between junctions to straight lines and thereby uses less screen area. The implementation is done using mobile web approach and web services to reduce the platform dependency. OpenStreetMap is used as the main data source with sample local landmarks. All technologies used are free and open source. The application is still being verified and tested in Sri Lanka.
( K. Chandrasekara Pillai ),( A. Senthil Kumar ),문일식 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Despite the unparalleled extensive use of ruthenium dioxide (RuO<sub>2</sub>), in both crystalline and amorphous forms, in a wide range of electrochemical applications, the intrinsic electron-transfer (ET) rate constant estimations at RuO<sub>2</sub> electrodes prepared at different temperatures are not reported in detail. In this paper, the ET rate constants for RuO<sub>2</sub> electrodes are estimated by rotating disk electrode (RDE) technique using an oxide-sensitive, non-interacting Fe<sup>3+</sup>/Fe<sup>2+</sup> redox probe. Chemically modified RuO<sub>2</sub> electrodes using oxide powders assembled on Pt support using polyvinylchloride binder are used. RuO2 powders prepared at five temperatures, 300 to 700°C, are studied to investigate the dependence of ET activity of electrodes on the oxide preparation temperature.