iPURSE 2015

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/41

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Application of the coupled energy simulation and computational fluid dynamics approach for predicting energy performance of buildings
(University of Peradeniya, Sri Lanka, 2015-11-06) Bandara,R.M.P.S.; Attalage,R.A.
Buildings account for nearly 40% of the global energy consumption and hence presently high emphasize is placed on improving the energy performance of buildings. Energy Simulation (ES) is the most popular approach in predicting the energy performance of buildings during their conceptual design stage. However, it is observed that this methodology shows certain inherent deficiencies in predicting the energy performance of buildings. Energy Simulation tools do not have the capacity to model air circulation through the building space explicitly. ES tools mainly rely on the simplifying assumption that air within a thermal zone of a building is well-mixed. Furthermore, convective heat transfer coefficients of building surfaces are calculated using set empirical correlations. Literature also reveals that most Energy Simulation tools under-predict energy consumption in buildings, especially under sunny conditions. On the other hand, Computational Fluid Dynamics (CFD) tools can predict airflow field, velocities, relative humidity and contaminant concentrations within an occupied space of a building extensively and accurately. Also, they are capable of determining the temperature distribution within the building space and convective heat transfer coefficients of the building envelope. However, CFD simulations need to be provided with the corresponding boundary conditions of the computational domain, which are readily available in the Energy Simulation approach. On this basis, the paper explains how Energy Simulation can be coupled with Computational Fluid Dynamics in predicting the energy performance of a building more accurately through complementary data exchange between the tools. The office building considered in the study is to be constructed in the suburbs of Colombo. The analysis uses ENERGYPLUS 8.0 and ANSYS FLUENT 6.3 as the tools for conducting Energy Simulation and Computational Fluid Dynamics respectively. MATLAB R2012a establishes the coupling platform. The study shows that the coupled approach predicts considerably higher energy consumption for the building compared to that given by conventional Energy Simulation using ENERGYPLUS.
Runoff model development for Nilambe catchment in Sri lanka using hec-hms
(University of Peradeniya, Sri Lanka, 2015-11-06) Priyankara,W.M.S.; Weerakoon,S.B; Nandalal, K.D.W.
Assessment of catchment runoff plays a vital role in catchment management. Hydrologic models are used as tools to simulate hydrologic processes and estimate catchment runoff parameters. But it is a challenging task to calibrate such models to represent real situation due to the limited data availability. In this study, Hydrologic Modeling System (HEC-HMS), developed by the Hydrologic Engineering Center, USA has been used to set up run off simulation model for the Nilambe catchment of the Mahaweli River located upstream of Polgolla reservoir in Sri Lanka. The Nilambe catchment was selected due to its importance to hydropower generation by Nilambe Hydropower Plant installed utilizing the runoff of the catchment. The Nilambe catchment was divided into 17 sub-catchments considering the hill-slopes and stream network. Clark unit hydrograph was selected as transport method with relevant time of concentration values for sub-catchments. Initial and constant loss method was used for flow calculation and constant loss value and imperviousness were used as calibration parameters. Recession base flow method with ratio to peak threshold method was selected to calculate base flow. The model was calibrated for a period of one year from 01 April 1992 to 30 March 1993. The validation of the model was carried out for the period from 01 November 1993 to 31 October 1994. Calibrated model suggests a constant loss rate of 5 mm/h and percentage imperviousness of 28% for the initial and constant loss method. The recession constant of 0.98 and the peak to ratio of 0.18 of the threshold method was used. The calibrated model is a useful tool for water resources development planning in the Nilambe catchment or similar hilly catchment in the Mahaweli basin. The model was used to generate daily runoff of the Nilambe catchment for 20 years period from 1976 to 1996, and the flow duration curve was developed. It is found that the energy output from the Nilambe hydropower plant can be increased by about 18% with a Plant factor of 30% by increasing the design discharge to 6.3 m3/s from present 3.6 m3/s.
PD signature identification using rf antenna for condition monitoring in power transformers
(University of Peradeniya, Sri Lanka, 2015-11-06) Wijewarden,D.K.; Sheree,J.N.N.; Karunarathna, K.M.D.E.; Fernando,M.A.R.M.; Kumara,J.R.S.S.; Uduwawala,D.N.
Power transformer is a vital component in a power system. So to maintain the reliability of the power system, continuous condition monitoring of the power transformer is essential. To monitor its condition, one of the best ways is to monitor the status of partial discharges (PDs) appearing in the transformer. With aging of power transformers in the service, their insulation may get aged. As a result, PD may occur in the transformer as corona discharges in air cavities or in oil, or as surface discharges in its insulation interfaces etc. This paper deals with monitoring and analyzing of common types of PD patterns occurring in a power transformer. In this paper, a Radio Frequency (RF) antenna was used to detect the electromagnetic signal generated due to three types of PDs i.e. corona in air, corona oil and surface discharge at interface. With preliminary investigations of different types of RF antennas by trial and error method, a loop antenna of diameter 200 mm was selected for the study. The three types of PDs were generated from laboratory set-ups. The corona set-up in air was prepared by a point plane gap with a gap setting of 20 mm whereas corona in oil was generated by dipping the same set-up in an oil container. The surface discharges were generated by keeping a transformer pressboard of thickness 5 mm between rod plane electrode system. Measured breakdown voltages for the setups used to generate corona in air, in oil and surface discharge were 25 kV, 30 kV and 10 kV respectively. The loop antenna was placed 1 m away from the setup and the captured RF signals were observed using a spectrum analyzer (anritsu-MS2661C-range 9 kHz-3 GHz) at different voltages up to 1 kV below the respective breakdown voltages. The antenna was aligned in such a way that the magnetic field generated by the PD was perpendicular to the plane of the loop. In preliminary investigations, it was identified that the presence of the PD signal was high in 5 to 60 MHz frequency range. After analyzing the final results which were taken 1 kV below the respective breakdown voltages of each PD types, the power spectral density distributions were compared.. The highest peaks of three responses were observed at 9 MHz, 8 MHz and 8.5 MHz for corona discharge in air, corona discharge in oil and surface discharge respectively. Their magnitudes varied as 22dBm, 19 dBm and 17 dBm for corona discharge in air, corona discharge in oil and surface discharge respectively. When the HV supply was decreased the magnitudes of the spectral responses were reduced. It was found that the PD strength varied with the supplied voltage level. It can be concluded that RF antenna can effectively be used to identify different PD patterns
Design of the buck converter for a current controlled photovoltaic emulator
(University of Peradeniya, Sri Lanka, 2015-11-05) Godakumara,G.P.M.; Senevirathne,E.H.; Binduhewa,P.J.; Ekanayake,J.B.
The modern developing world is inclining more towards renewable energy. Photovoltaic (PV) systems are a major renewable energy source. A number of PV panels are commercially available with different voltage and current ratings. Different PV modules should be used in different applications depending on their power demand, environmental constraints and the nature of the existing power system. It is necessary to test these systems prior to installation as well as for research purposes. It is infeasible to do this testing using actual PV panels as the PV panels are expensive. A PV emulator can be used in these testing purposes. PV emulator is an electronic device which mimics the characteristics of a PV panel under different environmental conditions. PV emulators based on various technologies have been proposed over the years. This design gives a low cost PV emulator integrating a buck converter, a current controller and a PV model. In the proposed system, a current controller takes the inductor current of the buck converter as a feedback and it compares with a reference current. The error is fed to a PI controller which is used to generate the Pulse Width Modulated (PWM) signal. The reference PV current is generates by a PV model that takes temperature, irradiance level and output voltage of the buck converter as inputs. This paper presents the design and simulation of a buck converter for the photovoltaic emulator. The basic equation related to the components of the converter is derived. Initial design was done for a PV panel with Maximum Power Point (MPP) current of 1.1 A, MPP voltage of 17.5V, short circuit current of 1.2 A and an open circuit voltage of 22.4V. The converter was designed to operate at the MPP. The designed converter was simulated using EMTDC/PSCAD software. As the PV panel operates at two extreme conditions (open circuit condition and short circuit condition), the behavior of the converter at these two extremes were analyzed. The converter was designed to have inductor current ripple of 30% and output voltage ripple of 5%. The simulation shows that the designed buck converter can achieve the desired output current with a ripple below 30% and output voltage at a ripple below 5% throughout the characteristic curve. This concludes that the designed converter can be used to obtain the required output current and voltage in generating the current-voltage characteristics of a PV panel with an acceptable accuracy.
Pv inverters to enhance the utilization of ac networks
(University of Peradeniya, Sri Lanka, 2015-11-06) Udagedara,U.M.T.D.; Senevirathne,M.R.I D.; Shameel,A.F.M.; Binduhewa,P J.; Ekanayake,J.B.
In many LV distribution networks, voltage drops in distribution lines causing many problems for sensitive equipment connected to these lines. The issue of poor voltage profile on distribution lines may be severe with the connection of electric vehicles as users will start charging them after returning home. As a solution to this problem, in this paper a reactive power compensation mode of PV inverters is investigated. Number of PV installations is rapidly growing and grid tie PV inverters operate only during the day time. In this project PV inverters are to be used to inject reactive power to the system at night, thereby enhance the voltage profile of distribution lines. During the day time, active power generated by PV panels is delivered to the system through the PV inverter. Any excess capacity is used to supply reactive power. At the night since PV panels are inactive, full capacity of the inverter is used to generate reactive power. The flow of active power through the PV inverter is controlled by applying an appropriate phase shift to the inverter output voltage with reference to the line voltage. In order to control the reactive power flow, the magnitude of the inverter output voltage is varied with respect to the magnitude of the distribution line voltage. If inverter output voltage magnitude is maintained above that of the distribution line, inverter can be operated as a reactive power generator. And also it can be operated as a reactive power consumer if necessary. A controller for the PV inverter which regulates the active and reactive power was developed. Inverter output current was measured and depending on the measured current, two orthogonal time invariant dc components as direct component and quadrature component were derived. These components were controlled to follow the given current references such that active and reactive power flow can be regulated independently. The operation of the concept was proved by simulations. Accordingly, PV inverters can be used to maintain a proper voltage profile along distribution lines by supplying reactive power on demand. It will also enhance the utilization of distribution network and the productivity of PV inverters.
Frequency domain ica based signal restoration from non-linearly distorted acoustic signals with dropouts
(University of Peradeniya, Sri Lanka, 2015-11-06) Sumanapala,Dilika; Sumanapala,Dinuka; Thushan,S.; Godaliyadda,G.M.R.I.; Ekanayake,M.P.B.; Wijayakulasooriya,J.V.
Independent Component Analysis (ICA) is a class of blind source separation which can be successfully used for extracting unknown independent source signals from acoustic signal mixtures. In this study, we introduce a new process based on frequency domain complex valued ICA for separation of sound sources from a distorted set of acoustic signals with random dropouts/audio gaps of the same source. The conventional time domain ICA algorithms can be effectively used for extraction of sources under linearly mixed conditions. However, the time domain algorithms are incapable of extracting the source signal under non-linear conditions. Therefore, our new method is targeted for extracting acoustic source signal when several non- linearly distorted and corrupted audio signal samples are available. It was also found that the frequency domain algorithm has a superior performance compared to the conventional real valued time domain ICA algorithm. Therefore, this algorithm can be used as an effective method for acoustic signal processing applications.
Identifying impact of work life conflict on job satisfaction
(University of Peradeniya, Sri Lanka, 2015-11-06) Lankeshwara, P.
Ceylon Electricity Board (CEB) is a body corporate for electricity undertaking in Sri Lanka. It conducts its massive duties to the Sri Lankan public though Generation, Transmission, Distribution and other services. One of the major problems that the results of pilot survey has revealed is that, among the CEB workforce many of non-executive staff in CEB-Sabaragamuwa are facing problem of work life conflict. At present the conflict between work and family has become a crisis for organizations. With the increase in dual family parents, more job demand and long working hours made it almost impossible to create a balance between work and family. This situation automatically reduces job satisfaction of the employees and then affects the productivity and profitability of the organization. The overall objective of this research was to analyze the factors related to work life conflict and its impact on job satisfaction at the CEB-Sabaragamuwa Provincial Office. The data were collected by distributing a questionnaire and the sample has comprised 120 non-executive employees. Pearson correlation test and Regression analysis were utilized as data analysis techniques. The results revealed that work life conflict impacts on reducing the job satisfaction. Further, family to work conflict could be identified as the most critical predictor. Ultimately work life conflict of non-executive staff employees of CEB negatively impact on their job satisfaction. The relationship between work life conflict and job satisfaction is inversely related to each other.
Mobile phone as a mode of information provident to up country vegetable farmers in Sri Lanka
(University of Peradeniya, Sri Lanka, 2015-11-06) Perera, D.G.D.; Mahaliyanaarachchi, R.P.; Sivashankar, P.; Hettiarachchi, I.C.
This study explores the status of mobile usage as a mode of providing information to the agriculture community in the upcountry region in Sri Lanka. The objectives of the study were to find out the awareness level, usage, attitudes of upcountry vegetable farmers about the mobile phone based information systems and services, to find out the factors affecting on mobile usage by farmers and their willingness to pay for mobile phone based information systems and services. Primary data were collected using an interviewer administrated questionnaire (n=120). Findings reveal that the access to mobile phones was considerably higher among the study group, while income had an effect on using a mobile phone. Most of the farmers use mobile phones to communicate with family, friends and relatives. Only few farmers use them effectively to obtain agriculture related information. Awareness and usage of mobile phone based information systems and services are at a lower level. Attitudinal barriers and less awareness are the major reasons for this situation. There is a positive relationship between the usage of mobile phone based information systems and services and farmers attitudes on its impact on knowledge and income. Farmers who are using the mobile phone based information systems and services highlighted that the services are very much helpful for agriculture development.
Unemployment, official economy and dimensions of the shadow economy: an empirical analysis for Sri Lanka using sem approach
(University of Peradeniya, Sri Lanka, 2015-11-06) Samaranayake, D.I.J.; Dayarathna-Banda, O.G.
Economists and policy makers confront a series of issues when accounting all unobserved market fractions in a challenging market economy. These challenges have become worse within complex market structures in developing economies. One of these challenges is the expansion of unobserved and unofficial economic activities which is generally known as the ‘Shadow Economy’. This study basically attempts to estimate the Sri Lankan shadow economic activities as a percentage of official estimates, while revolving the wheel of non-clarified zones and market functions through overstepping the traditional official estimates. Objectives of the study are addressed through three equally important portions. Initial portion intend to choose and develop suitable, fitted MIMIC (Multiple Indicator Multiple Cause) models while using the structural relationship between the unemployment rate and shadow economy to estimate the size of the shadow economy in Sri Lanka. Then the following portion is to estimate shadow economy for each fitted model through benchmark calculations. Finally, to examine if estimated models and their calculations are accepted by re-examination of Okun’s law and to contrast estimated results in growth terms to the growth of official estimates (GDP) of the economy. Therefore, the methodology involves the estimation of structural equation models, which analyses a set of causes of the shadow economy while simultaneously taking in to account its influence upon a series of indicators. This study introduces three MIMIC models through the analysis that are MIMIC 5-1-2a, MIMIC 4-1-2b and MIMIC 3-1-3a. Then the benchmark calculations for each model derives a series of average values for the Sri Lankan shadow economy from 1990-2012. Calculations for MIMIC 5-1-2a vary between 91% and 32% from 1990 to 2012 with a decreasing trend. On the other hand, calculations for MIMIC 4-1-2b and MIMIC 3-1-3a demonstrate the average size of shadow economy between 14% and 52% with an increasing trend. Further discussions, therefore, reveal the fact that, the effect from tax on goods and services to the government revenue and the effect from public employment tend to undermine the increasing pattern of shadow economy in Sri Lanka. Since unemployment rate and private employment plays a major role in economy, shadow economy tends to increase. Eradicating the workplace enforcement crisis and underemployment issues may hinder the increasing pattern. Ultimately, the results from re-examination of Okun’s law give a hint that the growth of shadow economy and official economy are not interdependent and have a parallel growth with shifting stages in market functions.
The impact of corporate social responsibility (csr) on brand equity : a study with special reference to Sri Lanka telecom plc
(University of Peradeniya, Sri Lanka, 2015-11-06) Shibly, F.H.A.; Hilal, M.I.M.
Today, Investment on Corporate Social Responsibility (CSR) has become the common business practices in the world. CSR is receiving increasing attention, especially in recent decades. At the same time, various stakeholders, especially, shareholders are more frustrated with the investment on the Corporate Social Responsibilities which will affect indirectly to the Brand Equity of the organization. Further there are various pros and cons about CSR, which impact the brand equity of the organization. Sri Lanka Telecom PLC (SLT) is the blue chip company in which CSR has become the most common practices in the SLT business agenda. The SLT has invested on CSR aspects. It is found that there are only few researches have been carried out in Sri Lankan context to find out the impact of CSR on brand equity and there is a need to measure it for organization’s effective CSR decision makings. The major objective of this research is to explore and investigate how a company’s corporate social responsibility activities are influencing its brand equity. By reviewing the existing literature on CSR and brand equity of the SLT, this study developed a better understanding of gaps that exist. In order to achieve the objective, the research draws from well-established theoretical models; the Caroll model which presented four variables on CSR. This model has been used by many researchers to measure the CSR activities of firms. According to this model, there are four perspectives such as economic, social, legal and ethical perspectives and the Aakers’ model has been used to measure the brand equity. The research adopted quantitative method to explore impact of CSR on brand equity of the SLT and data were collected by means of online survey tool and printed questionnaires. A survey was conducted among 100 customers who use the SLT services. Regression and correlation analysis, including partial correlation, linear, binary logistic regression, was used to obtain the results that helped identify the impact of CSR on brand equity of the SLT. The results of the study showed that corporate social responsibility is positively impacted on brand awareness, brand loyalty, perceived quality and brand association of the SLT PLC. Thus there is a positive impact of CSR on brand equity and if the SLT invests more on CSR activities, the value of their brand equity will be increased.
Forecasting international tourism income of Sri lanka : trend analysis
(University of Peradeniya, Sri Lanka, 2015-11-06) Konarasinghe, K.M.U.B.
Growth of the tourism industry in Sri Lanka shows the historical development mainly in two ways. That is the growth of tourist arrivals and income. Tourism impacts on the economy of Sri Lanka, which rely heavily on foreign exchange earnings. This has been a general interest of the government. Therefore, the government needs reliable forecasting to cope with uncertain situations and developing sound strategies to maintain the growth of tourism industry. This study was focused on identifying an appropriate trend model for forecasting international tourism income of Sri Lanka. Monthly income data from 2009 to 2013 were obtained from statistical reports of 2012 and 2013 of Sri Lanka Tourism Development Authority (SLTDA). The study concerns the period of post-war, which is after the year 2009. Model fitting was done by utilizing data from January 2009 to April 2012 and data from May 2012 to May 2013 were utilized for model verification. Four trend models were tested with log transformation including one linear and three nonlinear models. Residual plots and Anderson-Darling tests for residuals were used as the model validation criterion. Forecasting ability of the models was assessed by considering Mean Absolute Percentage Error (MAPE), Mean Square Error (MSE) and Mean Absolute Deviation (MAD). Box and whisker plot showed no outliers in the data set. Results revealed that Quadratic Trend Model has least MAPE’s in model fitting and verification: 0.90% and 1.12 %, respectively. MAD and MSE also confirmed the smallest deviation compared with other trend models. Residual plots and Anderson-Darling test confirmed the normality of residuals. Also, residuals Vs fits confirmed the independence of residuals. It was concluded that the Quadratic Trend Model with log transformation is suitable for forecasting international tourism income in Sri Lanka. Monthly income for the period from May 2012 to November 2013 were forecasted by the model and found them close to the actual income. It is recommended to try other time series techniques, namely, decomposition techniques, Auto Regressive Integrated Moving Average (ARIMA) models etc., to capture the seasonal behavior of the series.
Decolourization of crystal violet synthetic dye from aqueous solution by woody biochar
(University of Peradeniya, Sri Lanka, 2015-11-06) Wathukarage, A.; Iqbal, M.C.M.; Priyantha, H.M.D.N.; Vithanage, M.
Colour removal from textile effluents prior to their disposal is an emerging concern due to its adverse effects on the environment and public health. Biochar can be used effectively as a biosorbent for removal of dye contaminants. This study investigated the adsorption of a basic dye, Crystal Violet (CV), from aqueous solutions on to biochar derived from Gliricidia sepium pyrolysed at 700 °C (GBC700). Pyrolysis was done under a heating rate of 7 °C min⁻ ¹. The adsorption process was investigated through batch experiments by varying pH, adsorbent dose, initial dye concentration, and contact time. The sorbent dosage, initial dye concentration and contact time were set as 0.5 - 6.0 g L⁻¹, 5 - 200 mg L⁻¹ and 5 min - 24 hr, respectively. The effect of pH was determined through edge experiments at pH 3 to 9. The equilibrium data was analyzed using the Langmuir, Freundlich and Hill isotherm models. Pseudo first order, Pseudo second order and Elovich kinetic models were used to investigate the kinetic data. Results indicated that the optimal adsorbent dose was obtained at 2 g L⁻¹ and the optimum contact time was 12 hr. The adsorbed amount was increased from 5.5 mg g⁻¹ at pH 3 to 8.0 mg g⁻¹ at pH 9 while the equilibrium was reached at pH 7. Since higher pH conditions lead to increasing the negative charge density of GBC700 and the electrostatic attraction to the dye cations can be enhanced. Crystal Violet removal efficiency was 99% at 20 mg L⁻¹. According to the Langmuir model, maximum adsorption capacity was observed at 30.4 mg g⁻¹ at 30 °C. The experimental data fitted well with the Freundlich isotherm model (r² = 0.9788) and Pseudo second order kinetic model (r² = 0.9703) which suggests the importance of multilayer adsorption to heterogeneous sites in biochars. The adsorption process is highly pH dependent. Crystal Violet molecule may interact with the GBC700 through the mechanism of 𝝅-𝝅 electron donor-acceptor interactions between the π-electron rich graphene surface of biochar and 𝝅-electron deficient CV dye molecule. The use of Gliricidia biochar pyrolysed at 700 °C could be a sustainable solution to remove CV in aqueous media while compromising the waste problem by using Gliricidia byproduct.
Climate change adaptation practices in crop cultivation : case study in Anuradhapura district
(University of Peradeniya, Sri Lanka, 2015-11-06) Ranasingha, R.M.C.K.; Nanthakumaran, A.
Climate change, mainly the variation in rainfall in the recent past years, causes frequent floods and drought in many districts in the country. The variation in rainfall and frequent floods and droughts affect the crop cultivation, and thereby challenging the food security of the country. Further, it affects the livelihood of the farming community in the tank based agriculture systems which includes the major and the minor irrigation tanks. Many minor irrigation tanks receive water from rainfall, store and supply for agriculture during non-rainy season. Very often the water stored in the minor irrigation tanks is not sufficient to fulfill the water requirement for agricultural purpose, because of the limited tank storage. The objective of this study was to identify the adaptation measures practiced by the farmers to overcome the effects of climate change due to rainfall variation under minor irrigation tanks. Since Anuradhapura district lies in the dry zone of Sri Lanka and many small and marginal farmers involved in crop cultivation, it was selected for this study. Stratified random sampling was done to select 150 farm households from 15 minor irrigation tanks in Anuradhapura district. Primary data from the farm households using structured questionnaire and the rainfall data for the past 31 years from the year 1984 as secondary data from the Meteorology Department were collected for analysis. Percentage analysis and the graphical representation were carried out using MS Excel. During 1984 to 2014 the average annual rainfall was 1293 mm with a coefficient of variation of 22 percent. The rainfall was above normal in 13 years with a deficit in 13 years, and very scarce in five years. The survey revealed that the crop insurance, cultivation of short duration crops, cultivation of drought tolerant rice varieties, inter cropping, changing the planting and harvesting date and agro forestry were some of the adaptation strategies practiced by farmers in the study area. The percentage analysis revealed that 94% of the farmers had crop insurance, 90 % of the farmers cultivated short duration crops, 72% of the farmers switched to cultivation of drought tolerant varieties, 46% of the farmers practiced intercropping, 30% of the farmers changed the planting and harvesting date, and 28% of farmers practiced agro forestry strategy as adaptation measures for climate change. Though the farmers in the study area practiced these climate change adaptation strategies to some extent, dissemination of knowledge about appropriate adaptation strategies towards farming community is essential to protect the livelihood of the farm households, while ensuring the food security of the country. Thus, the farmers may be given proper support by supplying short duration and drought tolerant rice varieties and selected seedlings for agro forestry.
Applicability of colorimetric organic matter determination and its relationship with total soil nitrogen for selected soils in Sri Lanka
(University of Peradeniya, Sri Lanka, 2015-11-06) Darshana, E.M.A.; Nandasesna, K.A.
Soil Organic matter determination using Colorimetric determination is a simple and less time consuming method which has not been tested for Sri Lankan soils yet. Soil Organic matter determination using Walkey and Black method (Volumetric determination) is a very common method. It is more laborious, time and chemical consuming. Relationship between soil Nitrogen level and colorimetric soil organic matter content is also useful to predict soil Nitrogen level. The objectives of this study were to investigate the applicability of colorimetric determination of soil organic matter to Sri Lankan soils and to investigate the relationship between soil Nitrogen and soil organic matter. Fourteen soils, varying in C content, were collected from agricultural fields at 0-30 cm depth differing in physico-chemical and other characteristics. In colorimetric method, 1 g soil samples were placed in 100 ml volumetric flasks followed by the addition of 10 ml of 1/6 N K₂Cr₂O₇ and 20 ml of concentrated H₂S0₄. The samples were mixed by swirling the flask and then and allowed to stand on a pad for 30 minutes in a fume cupboard. After bringing to a volume of 100 ml, the mixture was filtered and analyzed for light absorption at 600 nm using spectrophotometer. Colorimetric organic matter values showed strong correlation with organic matter determined by volumetric (Walkey and Black, 1934) method (r=0.95). Organic matter determined from both methods showed no significant difference. Colorimetric method organic matter values showed strong correlation with total Nitrogen (r=0.75). It is confirmed that colorimetric method can be used effectively and reliably to determine soil organic matter in Sri Lankan soils and total Nitrogen in soil can also be predicted.
Assessment of green space in the colombo city liaisons with gis and in-situ data
(University of Peradeniya, Sri Lanka, 2015-11-06) Madurapperuma, B.D.; Kuruppuarachchi, K.A.J.M.
Urban sprawl in Colombo City is increasing due to centralization of social and economic endeavors. Urban forests and green infrastructure make the city cleaner and healthier to raise the standard of environment quality and aesthetic beauty. This study examines the green urban space in Colombo City using geographic information system and green cover was compared with in-situ ground truthing data in selected locations. A supervised learning algorithm was adopted to classify ESRI base image to three major land-use/cover classes: green space, built-up and water using training samples within Colombo City. Landsat 8 satellite imagery that acquired on 14.04.2015 was used to calculate Normalized Difference Vegetation Index (NDVI). Then green space of the NDVI image was extracted using polygonal vector feature class of the classified image. The results showed that 29% of the area was green space, 67% was built-up and 4% was water. Coefficient of agreement (Khat) was calculated for the classified image resulting in 0.81 overall accuracy. The NDVI values showed the intensity of greenness of vegetation. The difference of NDVI values were compared using available base maps. Then NDVI results were utilized to assess the green space in the field systematically to gauge how species contributes for varying greenness. The results and the method adopted in this study eventually provide valuable insights for city planners and policy makers to establish new green urban space to uplift environmental quality of potential sites in Colombo City.
Preliminary study on use of activated coconut coir as adsorbent for removal of chloride and fluoride in water
(University of Peradeniya, Sri Lanka, 2015-11-06) Bandara, H.K.M.S.N.; Kottegoda, N.; Perera, A.D.L.C.
Chlorine is a powerful germicide used in killing many disease-causing microorganisms in drinking water and reducing them to almost non-detectable levels. However, it can react with organic matter in the water and form dangerous, carcinogenic trihalomethanes if present in excess. Fluoride has beneficial effects on teeth at low concentrations in drinking-water, but excessive exposure to fluoride in drinking-water, or in combination with exposure to fluoride from other sources, can give rise to a number of adverse effects. This is a preliminary study to investigate the ability of activated coconut coir (ACC) to remove Cl ⁻ and F⁻ anions in water. Coconut coir, a lignocellulosic polymer, was activated by treating with phosphoric acid followed by pyrolysis and used as an adsorbent for the removal of Cl⁻ and F⁻ anions from an aqueous solution. Activated product was characterized by Fourier Transform Infrared (FT-IR) Spectroscopy, Scanning Electron Microscope (SEM) and X-ray diffraction techniques and adsorption capacity was measured using methylene blue number. Chloride and fluoride ion removal ability of activated coconut coir was studied by using standard salt solutions of KCl and NaF, respectively. The concentration of Cl⁻ was determined using chloride ion selective electrode and that of F⁻using SPADNS (sodium-2-(parasulfophenylazo)-1,8-dihydroxy-3,6-napthalene) reagent. After activation, coconut coir gains more porosity and adsorption capacity. This can be attributed by the high Methylene Blue (MB) number of 331.30 mg g⁻¹obtained for ACC. The FT-IR data indicates appearance of new functional groups such as carboxylate and phosphate after activation process. The Powder X-Ray Diffraction pattern of synthesized ACC sample showed a peak at an angle of 2θ = 24° corresponding to the hexagonal graphitic carbon structure of (002) plane. The surface morphology and pore structures were analyzed using SEM; SEM images of activated product showed pores in the nanometer size scale. The Presence of nanometer size pores introduces higher adsorption capacity into the ACC. The maximum percent removal of Cl⁻ observed was 30% and that of F- was 40% in single filtration. The equilibrium adsorption studies of Cl ⁻ and F ⁻ anions show that experimental data fits well to linear forms of both Freundlich and Langmuir isotherms implying homogenous and monolayer coverage. The Langmuir constant for Cl ⁻ was 388.00 dm³ g⁻ ¹ and that for F ⁻ was 420.00 dm³ g⁻ ¹ The Freundlich constants for Cl⁻ and F⁻ were 0.022dm³ g⁻ ¹ and 0.012dm³ g⁻ ¹, respectively. The phosphoric acid activated coconut coir has the potential to be used as low-cost adsorbent for the removal of Cl⁻ and F⁻ anions from water.
Modelling the temporal dynamics of soil moisture content of a yellow latosol
(University of Peradeniya, Sri Lanka, 2015-11-06) Gierthana, M.; Vitharana, U.W.A.; Suthakar, S.
Soil moisture is a key variable that control exchange of water and heat between the land surface and atmosphere. Knowledge on the dynamics of soil moisture and there management are paramount steps to improve crop production. In this study, a simple hydrological model was assessed to estimate the temporal dynamics of soil moisture content of a Yellow Latosol at Regional Agricultural Research and Development Centre in Kilinochchi. The input parameters required for the model (Chopra model) are initial soil moisture and surface boundary flux conditions along with few easily measurable soil physical parameters. This model also predicted the soil moisture contents at different depth intervals and at different time intervals. To investigate functioning of the model, input data were obtained from available literature databases, laboratory analysis and pedo-transfer functions. Soil samples were collected at the depth of 0-15 and 15-30 cm every morning at same time for a twenty days period from each location for moisture content measurements. Measured and predicted moisture contents of the surface soil were compared using root mean square error (RMSE) and residual error (RE) values. The result indicated that the RMSE values for modelled moisture content were within the range 0.02 to 0.08 and the RE values from 2 to 8%. When input data from three different sources were used the residual error is less than 10%, which is reported as an acceptable level of prediction accuracy. This model produced most accurate predictions when the values of input parameters from laboratory analysis were used. Hence, this model can be applied to generate temporal dynamics of soil moisture data with an acceptable accuracy for agricultural purposes.
Communication and adoption of waste management practices of urban and semi-urban households in Trincomalee district
(University of Peradeniya, Sri Lanka, 2015-11-06) Ganegoda, P.; Wanigasundera, P.
Waste disposal has become a serious issue in Sri Lanka, making her one of the highest waste generating countries in Asia. Previous research findings state that the key to successful waste management system is the cooperation of citizens, which could only be gained through public awareness, which is lacking in Sri Lanka. Thus, the focus of this research was to find out the role communication has in creating awareness and promoting adoption of waste management practices. Moreover, the research specifically focused on finding out the communication channels by which people receive information of waste management and the message content of those channels affecting the level of awareness and adoption of waste management practices. The data gathered from three purposively selected Divisional Secretariat divisions based on the ethnicity, as the study area is a multi-ethnic area; 200 households were selected randomly from both urban and semi-urban GS divisions. Trincomalee Town and Gravets and Kinniya DS divisions, which are functioning under the urban councils, represent the majority of Tamil and Muslim populations, respectively, whereas Kanthale DS division functions under Pradeshiya Sabha represents majority of Sinhala population. Data were gathered using a questionnaire and analyzed using Statistical Package for Social Sciences. Results revealed that people received messages related to waste management by around 20 communication channels, which can be categorized into three: national mass communication channels, provincial formal communication channels, and informal communication channels. Among them, mostly used communication channel was the television. In addition, respondents used Public Health Inspectors, school education, Urban Council/Pradeshiya Sabha, and newspapers to receive information. However, a large amount of information respondents received was not directly related to waste management. The information received through school education, television, newspaper and non-governmental organizations showed a significant positive impact on awareness level, but, only school education had a significant positive impact on adoption level. In conclusion, the results emphasize that communication plays a major role in creating awareness of people regarding waste management. However, it alone cannot contribute to improve the adoption level, which requires the contribution of supporting services, such as the service of informal waste collectors and implementing rules and regulations.
Soil moisture response to convective rainfall
(University of Peradeniya, Sri Lanka, 2015-11-06) Nianthi, K.W.G.R.; Wickramagamage, P.; Rambukkange, M.P.
The climate of Sri Lanka is tropical monsoonal with a marked seasonal rhythm in rainfall. This rhythm is also reflected in the soil moisture because rainfall influences the soil water content. Soil moisture is known to play an important role in our environment and is thus considered an important climatic variable. Therefore, determining the relationship between soil moisture and rainfall are needed to characterize the climate variability. The usual practice is to use long term measurements of rainfall and soil moisture content to derive rainfall-soil moisture relationships. However, results obtained from long-term can obscure the short term behavior of a soil. High temporal resolution rainfall and soil moisture data from first inter monsoon season are used to investigate the response of soil moisture to individual rainfall events. High temporal resolution data are collected at the weather station of the Department of Geography. The moisture sensor is buried at 30 cm depth to capture the soil moisture in the effective root zone. The soil moisture variations during rainfall were investigated for April 2015. The study focuses on the response of soil moisture to individual rainfall events of different magnitudes and durations. There were 20 major rainfall events during the study period. An individual rainfall event and its corresponding moisture curves were observed. About 45% of rainfall events in April lasted for less than 30 minutes while 30% of the showers lasted for over an hour. In many cases, the peak rainfall occurred about 15 minutes after the beginning of a shower. High rainfall amounts usually triggered a peak in the soil moisture curve. The maximum observed soil moisture level was about 47%. Two types of soil moisture peaks were identified in the time series: sharp-pointed peaks and flat topped-peaks. The latter condition occurred during very long rainfall and/or large rainfall magnitudes. The soil moisture level at the beginning of the month of April was about 2.8%, but thereafter it did not fall below 6% during the rest of the month. This increase in minimum soil moisture level is most likely due to the cumulative effect of rainfall. Although approximately 35% of the showers had total rainfalls of less than 10 mm, the remainder of showers had higher rainfall amounts. These episodes were responsible for maintaining higher soil moisture levels and even driving the soil moisture to the saturation level. This study reveals that a small rainfall amount with a long duration or large rainfall amount with short duration can lead to soil water saturation. Most of the rainfall events were short (< 2 hours) and a majority of them (60%) occurred in the afternoon suggesting convective rainfall. The study reveals that approximately 15 mm of total rainfall is necessary to get soil moisture to saturation. This implies that rainfall duration is a critical factor in driving the soil moisture to saturation. It is apparent that rainfall duration of less than 30 minutes does not lead soil moisture to saturation. Frequent intermittent rainfall events during the month of April contributed to the overall increase in the soil moisture level compared to the previous month. This elevation in the soil moisture level could also have a significant impact on plants.
Very low frequency electromagnetic (vlf em) method for vein graphite investigation in crystaline rock terrain : a case study in Rangala, Sri Lanka
(University of Peradeniya, Sri Lanka, 2015-11-06) Karunarathne, K.M.P.C.; Dharmagunawardhane, H.A.
Vein graphite formations in Sri Lanka show systematic orientation rather than random. They follow define brittle structures alone in mineralized regions, but pinching out behaviour of veins make them difficult to be detected by traditional drilling methods. At present, exploration for new graphite veins is important factor for continuation of graphite industry. Electromagnetic Surveys are some of the most common survey methods in globe for the conductive mineral exploration. A Very Low Frequency (VLF) electromagnetic survey was carried out using EM 16 handheld instrument for the field data collection. Rangala graphite mine area is situated in the Kegalle district within the crystalline terrain of Sri Lanka. Survey grid was designed perpendicular to the primary signal transmitting direction. Positive to negative inphase reading variation along survey lines was used as primary indication of subsurface conductor. Simple numerical filtering method was used to reduce random fluctuation of the anomalies. Interpretation of individual anomalies indicated that the conductive zones present at an average depth of 10m-15m. These anomalies have followed vein orientation of NW-SE as shown by previous investigators. Overlapping of anomalies with already identified veins and drill hole data verified relationship between anomalies and graphite veins. At least fourteen conductive bodies were identified during the study, indicative of graphite veins. According to the anomalies, lengths of the veins vary between 20m-150m with steep dipping. VLF anomalies indicated a very significant correlation with the already located graphite veins, thus conforming the other anomalies represent yet undiscovered graphite veins. The study further revealed that VLF method can be effectively and economically used in graphite exploration in Sri Lanka, instead of costly drilling based investigations.

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