International Research Symposium on Pure and Applied Sciences (IRSPAS)

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Growth of CuZnS thin films by sequential electrodeposition and sulphurisation
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Fernando, W.T.R.S.; Jayathilekea, K.M.D.C.; Wijesundera, R.P.; Siripala, W.
Copper Zinc Sulphide (CuZnS) is a promising new absorber material for solar cell applications. Indeed, this material is very attractive for low cost device applications due to abundance and low cost of the staring materials. Very recently, a CuZnS based solar cell with In2S3 window material has been reported having Voc of 0.41 V, Jsc of 10.6 mA/cm2, FF of 45% and  of 1.94%. This initial finding has proven the possibility of developing this material as a solar energy material. Among the CuZnS preparation techniques, electrodeposition is an attractive technique because of its simplicity, low cost and possibility of making large area thin films. In this study, possibility of growth of CuZnS thin films by sulphurisation of electrodeposited Cu and Zn stack layers using S powder has been investigated. Cu thin film was electrodeposited on Ti substrate at –700 mV Vs Ag/AgCl for 15 min in an electrochemical cell containing 0.05 M sodium acetate and 0.005 M cupric acetate. Deposition of Zn thin film on Ti/Cu electrodes was carried out at -1.2 V Vs Ag/AgCl for 1 min in an electrochemical cell containing 0.2 M ZnSO4. Deposition parameters of Cu and Zn have been obtained by voltammograms. Set of identical Ti/Cu/Zn thin film electrodes having Cu/Zn ratio of 3.2 were prepared by maintaining the respective Cu and Zn thin film deposition durations for studying the sulphurisation process. In order to grow CuZnS, Ti/Cu/Zn thin film electrodes were annealed at different temperatures (400 oC, 450 oC, 500 oC, 550 oC and 600 oC) with different S contents (10 mg, 20 mg, 30 mg, 40 mg and 50 mg) for a duration of 60 min. CuZnS thin films were characterized using dark and light current voltage measurements in a PEC containing 0.1 M sodium acetate to obtain the best sulphurisation condition. Dark and light I-V characteristics revealed that the films annealed at 600 oC with the S content between 10 to 20 mg exhibits photoactivity. Further, photocurrent was always cathodic confirming the formation of p-CuZnS thin films. It was revealed in this preliminary investigation that the best photoactive films could be produced when films are annealed at 600 oC for 60 min in 20 mg S content. We have found, that photoactive p-CuZnS thin films can be grown by employing the technique of annealing electrodeposited Cu and Zn stack layers using S powder. Cu/Zn ratio of the stack layers could be the crucial parameter in determining the structure, conductivity type and resistivity of CuZnS films and therefore the methodology developed in this study could be further investigated, in order to develop the material for wider applications.
A survey on usage of canteens of University of Kelaniya by students of Faculty of Science
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dias, S.N.U.P.; Priyasad, H.A.D.; Manamperi, D.K.S.; Kumara, M.S.M.S.; Sandaruwan, D.M.S.; Pramoda, K. A.D.A.; Fernando, T.S.D.; Rashmi, W.A.D.; Ravindran, U.M.; Dhananjani, W.T.; Pitigalaarachchi, P.A.A.C.; Attanayake, A.M.C.H.
The university canteens while providing meals are an important meeting point for both students and staff members. There are several canteens within a university but service provided by canteens and therefore, students’ preferences for canteens may be different. This survey is based on five main canteens at the University of Kelaniya; Base, Gym, Hilton, Staff and Hostel canteens. The aim of this survey is to understand the usage of the canteens by students of the Faculty of Science. The objectives are to identify the frequently visited canteen of the students and the reasons for it, categorize the most visited canteen by gender, year of study, accommodation type, measure the satisfaction on available facilities of university canteens and classify the student expectations regarding the facilities. The survey was conducted during the period of September – November 2015. Among the 1394 students registered in the Faculty of Science, 255 respondents were randomly selected using simple random sampling method (without replacement). An appropriate questionnaire was developed in order to gather data and achieve the objectives. After a pilot survey was conducted, questionnaire was administered in person and online and also by interviewing busy students in order to collect data. The analysis reveals that the majority of students (41%) of the Faculty of Science visited Base canteen for their needs; whereas 25% visited Staff canteen and 22% visit the Gym canteen. The usage does not change irrespective of whether the student stays at the hostel, boarding place or home. The reason for using the Base canteen is convenience in reaching the canteen. Female students (49%) use the Base canteen whereas male students (38%) prefer to use Staff canteen. Lunch is the preferred meal compared to breakfast, dinner and other snacks. The majority of first year students visit the Base canteen, 2nd year students prefer to visit Gym and Staff canteens than the Base canteen and 3rd year students prefer the Base canteen. Majority of the students (29%) have ranked the condition of Base canteen as average and 14% have ranked as good. When considering the attitude of the staff members of the canteens, Base and Staff canteens’ employees have been highly ranked as ‘Average’ by most of the respondents (19% and 17% respectively) while ‘Good’ was marked by 15%. Most of the respondents have marked as ‘Average’ considering the service speed of canteens in the university and around 20% of students have claimed that the service speed is low over all canteens. In general, only 45% of the students are satisfied with the facilities provided by the canteens. Most of the students (23%) have requested to expand the space within the canteens and requested to have air conditioning, TVs and vending machines within the canteens. The survey discloses important findings about the usage of university canteens by students of the Faculty of Science.
Photosynthesis: Synthesis of what?
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Gunawardane, M.M.
The term photosynthesis is often used to mean the entire chain of biochemical reactions, which is initiated by light and concluded by the synthesis of carbohydrates. This series of reactions has two clearly distinct stages. First, there is the synthesis of ATP and reduced coenzymes (e.g. NADPH) with the help of light energy. Next, ATP and a reduced coenzyme are used in the synthesis of carbohydrates (e.g. starch) from CO2. As the first stage involves light, it is known as the light reaction of photosynthesis, while the second stage, which does not require light, is known as the dark reaction of photosynthesis. The dark reaction in nature is not a process necessarily dependent on a photomediated activity, the light reaction. What dark reaction needs for the reduction of CO2 into organic carbon is a reduced coenzyme and ATP, and the source of those compounds does not necessarily have to be the light reaction. This review proposes that the dark reaction should not be described as part of photosynthesis. Dark reaction is not a process limited to organisms that use photo energy to produce ATP and reduced coenzymes. In fact, without any dependence on photo energy, it happens in nature in some non-photosynthetic chemotrophic organisms as well. Thus, the light reaction is not an essential precondition for the dark reaction. Furthermore, ATP and reduced coenzymes synthesized by the light reaction in nature are not entirely used for the dark reaction. As such, the light reaction is not an activity that leads only to the dark reaction. Since the dark reaction can occur independently from any photo-driven synthesis process, it should not be described as part of photosynthesis. Therefore, the term photosynthesis should be confined to describe only the light reaction, defining photosynthesis as the process in nature that synthesizes ATP and reduced coenzymes using light energy. Dark reaction, which describes fixation of CO2 in to organic compounds, is an activity carried out by photosynthetic organisms and certain chemolithotrophic bacteria as well. It can be appropriately described by the term autotrophy, defining it as the primary production of carbohydrates in the biosphere.
Assessment of phytochemicals and antifungal effect of Croton aromaticus against postharvest fungal pathogens isolated from tropical fruits
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesundara, S.A.D.T.L.; Kannangara, S.; Abeywickrama, K.
Chemical control using synthetic chemical fungicides is still the most common method of controlling postharvest diseases of fruits. Plant extracts which are rich in antimicrobial secondary metabolites such as terpinoids, alkaloids, saponins and flavonoids could be possible alternatives for synthetic fungicides. Current study was focused on evaluating the antifungal effect of ethanolic extract of Croton aromaticus (Kappettiya) leaves in vitro against mycelial growth and the spore germination of postharvest fungal pathogens isolated from fruits of banana (Colletotrichum musae, Rhizopus sp., Lasiodiplodia theobromae) papaya (Rhizopus stolonifer, Colletotrichum gleosporioides, Lasiodiplodia theobromae) and mango (Alternaria alternata, Pestalotiopsis mangiferae, Lasiodiplodia theobromae). Surface sterilized diseased banana, papaya and mango fruit tissues were cultured on PDA plates in order to obtain pure cultures of possible fungi and they were identified by morphological and microscopic characteristics, using identification keys. Inhibitory effect of the ethanolic extract of C. aromaticus against test pathogens were investigated by well diffusion method using PDA medium, by incorporating crude extract dissolved in DMSO, ranging from 1 mg/ml up to 300 mg/ml concentrations along with the positive (Captan) and negative (DMSO) controls. Significant (P < 0.05) inhibitory effects were exhibited by the ethanolic extract of C. aromaticus leaves against all test pathogens except L. theobromae. The highest mycelial growth and spore germination inhibition of most of the pathogens were observed at 100 mg/ml. The lowest Minimum Inhibitory Concentration of the leaf extract (5 mg/ml) was observed for spore germination inhibition of C. gleosporioides and P. mangiferae. TLC analysis revealed four compounds having Rf values of 0.551, 0.672, 0.810 and 0.913. Phytochemical screening of ethanolic extract revealed the presence of alkaloids, terpenoids, quinones, phytosterols and flavonoids. Current findings indicate the potential use of ethanolic extract of C. aromaticus leaves in controlling banana, papaya and mango postharvest fungal pathogens in vitro.
Developing a model to identify the fade-away-impact of promotional activities over the financial performance
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Suraweera, S.A.M.S.; Wijayanayaka, A.
The lack of understanding on the impact of marketing activities on financial performance had made the validity of and the effectiveness of marketing, a questionable one. When a particular promotional tool is used, the impact of that particular promotional activity is not restricted to the current period, but the effect permeates across future periods as well. The study identifies this impact as ‘fadeaway- impact’ of promotional activities on the financial performance. Currently promotional activities are considered as costs which are deducted from revenues of the same month. This idea restricts the impact of promotional activities only to short term results and completely ignores the medium and long term impact of promotional activities on the revenue. The purpose of this study is to develop a model to identify whether there is a fade-away-effect of promotional activities over the financial performance and identify how the impact behaves over the time. Promotional activities brings tangible and intangible benefits. Most of the marketing literature is focused on understanding the immediate/short term impact of promotional activities on the financial performance. This motivates the use of longterm or persistence models instead of event windows to study the impact of tangible and intangible effects. In order to reach the above mentioned objectives, the researchers use the Lagging Effects of regression model and Markov Chain related theories. Steady state vectors of the Markov process understand how the impact of promotional activities varies over time when a customer repeatedly purchase a given brand/ product or switch to a different brand. Data related to Markovian analysis have been collected from a questionnaire and tested. Apart from this, the lagging effect of linear regression models were used to assess which degree of lagging period of promotional cost is significant to the financial performance. The monthly promotions expenditures and the related revenue figures were collected from different firms to study the lagging effect. The findings reveal that the impact of promotional activities have a lagging-effect on the firm’s revenue/financial performance by proving the significant existence of 2nd and 3rd order lags in the simple linear regression model. Further, it proves through the Markov process that the impact of promotional activities will never go to zero, but it will become steady creating brand equity for the firm after a certain period and that period could be measured in which the researchers identifies as the period of fade-away-impact. The outcomes of the research enables the Marketing managers to make informed decisions on the selection of promotions mix tools and thereby to manage the promotional expenditures effectively without reducing their profitability.
Semi-Automated Index based decision making engine for cyber foraging framework with minimal energy and performance cost
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Vekneswaran, P.; Dissanayake, N.R.
Cyber Foraging is a concept to take advantage of the nearby underutilized computing resources (surrogates) to improve user experience of resource constraint handheld devices, by improving their performance while improving battery consumption. It’s not always beneficial to offload the tasks to the surrogates so there is a need for a decision making engine to only offload tasks, which will result in overall improvement in performance and battery consumption. There are many attempts to enable cyber foraging in smartphones, each having their own decision making mechanisms, some using fully automated Machine Learning Algorithms and Heuristic Data; and it has been proven inefficient even though with higher accuracy. Furthermore, these approaches fail to deliver accurate results when it comes to new applications without any historical data. The key drawback of them can be seen as the resource intensive decision making engine, which negatively effects on the overall performance and battery consumption of the device. We introduce a model for decision making engine, which takes context parameters like remaining battery, worst case complexity of the method, etc. into account, when making the choice to offload or not to the surrogate, during the runtime. The engine benchmarks the surrogate according to their capabilities such as: available JVM memory, accessible processing cores, which can be harnessed by the surrogate service used by the cyber foraging enabled mobile application using static policies. These indexes will then be used to compare with the worst case complexity value, which the developer has assigned to the identified intensive parts of the application. This approach will give a satisfactory amount of accuracy with extremely low cost of energy and higher performance. Further research is being done on addressing more complex use cases with more advanced algorithms towards a stable and reliable solution.
Applicability of unsupervised learning algorithms for setting profiles for consumer buying behavior
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Paranavithana, I.R.; Rupasinghe, T.D.
The Consumer Buying Behaviour consists of a summation of attitudes, preferences, intentions and, decisions taken by them. The process that customer buys a product or service varies for each individual and each category of products they may purchase. With the development of Information Technology, the products and the behaviour of purchasing those products have drastically changed and become more unique to individuals. With respect to these changes, the data collection and analysis have become more dynamic and customer data has become larger and nosier in terms of volume and complexity. As a result of that, handling, analysing, and interpreting customer Point of Sale (POS) data has become a challenge for Retail Supply Chains (RSC) who wish to segregate customers into specific niche markets. Furthermore, it makes increasingly difficult for the retailer to find out when a person comes and buys the products from their outlets and to predict his/her behaviour for the subsequent purchases. As a solution for the aforementioned problems faced by the retailers, a novel a consumer buying behaviour profile mechanism is proposed. The profiles are created with respect to the frequency, time-stamp, and product category using a large POS dataset. The Unsupervised learning techniques were utilized in categorizing consumers in determining similar purchasing behaviour using K-means, Expectation Maximization, and Hierarchical Agglomerative Clustering (HAC). Along with the above clustering techniques, text mining techniques were used in categorizing the product descriptions to create the desired product categories. The study has used data from the UCI machine learning repository with 541,909 POS type records and has applied the aforementioned unsupervised learning techniques to setup the profiles. It has unveiled product related and non-product related charateristics for the given POS data and has laid a novel foundation to construct the profiles to determine buying behaviour. Furthermore, these profiles can be used in segmentation of consumers, RSC specific promotions, and to predict future possibilities to minimize inventory related problems.
Accelerating the rate of convergence of some efficient schemes for two-stage Gauss method
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Chamaleen, D.B.D.; Vigneswaran, R.
The non-linear equations obtaining from the implicit s – stage Runge-Kutta methods have been solved by various iteration schemes. A scheme has been developed, which is computationally more efficient and avoids expensive vector transformations. The rate of convergence of this scheme is examined when it is applied to the scalar test differential equation 􀀒􀀢 = 􀀣􀀒 and the convergence rate depends on the spectral radius 􀀤[􀀘(􀀦)] of the iteration matrix 􀀘(􀀦), where 􀀦 = ℎ􀀣 and ℎ is the step-size. In this scheme, supremum of a lower bound for 􀀤[􀀘(􀀦)] is minimized over the left half 􀀦- plane with the constraints requiring super-linear convergence at 􀀦 = 0 and 􀀦 → ∞ .Two new schemes with parameters are obtained for the two-stage Gauss-method. Numerical experiments are carried out in order to evaluate and compare the efficiency of the new schemes and the original scheme. Consider an initial value problem for stiff system of ordinary differential equations 􀀒􀀢 = 􀀬􀀭􀀒(􀀟)􀀮, 􀀒(􀀯) = 􀀰, 􀀬: ℝ􀀐 → ℝ􀀐. An s-stage implicit Runge-Kutta method computes an approximation 􀀒􀀳􀀴􀀜 to the solution x (􀀟􀀳􀀴􀀜) at discrete point 􀀟􀀳􀀴􀀜 = 􀀟􀀳 + ℎ by 􀀒􀀳􀀴􀀜 = 􀀒􀀳 + ℎ Σ 􀀛􀀶 􀀷 􀀶 􀀸􀀜 􀀬(􀀔􀀶 ), where 􀀔􀀜 ,􀀔􀀙 ,…,􀀔􀀷, satisfy sn equations 􀀔􀀶 􀀸 􀀒􀀳 + ℎ 􀀺 􀀯􀀶􀀻 􀀷 􀀶􀀸􀀜 􀀬􀀭􀀔􀀻􀀮, ), 􀀼 = 1,2, . . . , 􀁀. 􀁁 = 􀁂􀀯􀀶􀀻􀁃 is the real coefficient matrix and 􀀛 = [􀀛􀀜 ,􀀛􀀙 ,…,􀀛􀀷]􀁄 is the column vector of the Runge-Kutta method. Let 􀀔 = 􀀔􀀜 ⊕ 􀀔􀀙 ⊕ … ⊕ 􀀔􀀷 ∈ ℝ􀀷􀀐and 􀁇(􀁈) = 􀀬(􀀔􀀜) ⊕ 􀀬(􀀔􀀙) ⊕ … ⊕ 􀀬(􀀔􀀷) ∈ ℝ􀀷􀀐. Then the above equation in 􀀔􀀜 ,􀀔􀀙 ,…,􀀔􀀷 may be written by 􀁈 = 􀁉 ⊗ 􀀒􀀳 + ℎ(􀁁 ⊗ 􀁋􀀐)􀁇(􀁈), where 􀁉 = (1,1, … ,1)􀁄 and (􀁁 ⊗ 􀁋􀀐) is the tensor product of the matrix 􀁁 with 􀀑 × 􀀑 identity matrix 􀁋􀀐. The efficient scheme, which has been already proposed, is given by [􀁋􀀷 ⊗ (􀁋􀀐 − ℎ􀁌􀁍)]􀁎􀁏 = (􀁐 ⊗ 􀁋􀀐)(􀁉 ⊗ 􀁑􀀳 – 􀁈􀁏) + (􀁓 ⊗ 􀁋􀀐)( 􀁉 ⊗ 􀁑􀀳 – 􀁈􀁏􀁔􀀜) + ℎ(􀁕 ⊗ 􀁋􀀐)􀁇(􀁈􀁏) + ℎ(􀀌 ⊗ 􀁋􀀐)􀁇(􀁈􀁏􀁔􀀜), 􀁖 = 1,2, …, In this scheme, supremum of a lower bound for 􀀤[􀀘(􀀦)] is minimized over ℂ􀁔, where ℂ􀁔 = {􀀦 ∈ 􀁙 /􀀌􀁉 (􀀦) ≤ 0 } with the constraints 􀀤[􀀘(􀀦)] = 0 at 􀀦 = 0 and 􀀤[􀀘(􀀦)] = 0 at 􀀦 → ∞. The parameters for the two-stage Gauss method are obtained and Numerical experiments are carried out.
Isolation and characterization of rhizobia from leguminous plants
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesundera, S.H.; Halmillawewa, A.P.
Rhizobia play a significant role in agriculture. Their ability to fix atmospheric nitrogen through formation of root nodules in leguminous plants contributes in increasing legume yield. The present study was carried out with the aim of isolating rhizobial strains from legume root nodules and characterizing them to check their potential to be developed into biofertilizers. Tests were performed to detect plant growth promoting traits such as phosphate solubilization, nitrate reduction, abiotic stress tolerance, which contribute towards sustainable agriculture. Four rhizobial strains, namely C1-n1 (from Vigna unguiculata), P3-n1 (from Arachis hypogaea), L1-n1 (from Vigna unguiculata ssp. Sesquipedalis) and L2-n1 (from Vigna unguiculata ssp. Sesquipedalis) were isolated. They were characterized based on their morphological and biochemical features. Preliminary identification of isolates was done by observing their growth on yeast extract mannitol agar with congo red as well as their reactions to Glucose peptone agar test, Hofers’ alkaline test, and Lactose agar test. The isolated strain L2-n1, was identified as a slow growing alkaline producing one according to its reaction on bromo thymol blue medium, while others were recognized as acid producing fast growers. This result was congruent with their growth rates as well. All isolates gave positive results for oxidase, catalase, urease, and nitrate reduction tests and a negative result for indole, methyl red, gelatine hydrolysis and starch hydrolysis test. Two strains (L1-n1 and P3-n1) gave a positive reaction to Voges- Proskauer test, while only L2-n1 gave a positive result for citrate test. No isolate was able to exhibit swarming motility and phosphate solubilization. Furthermore, the capability of these organisms to utilize six different carbon sources and produce mucus colonies was also tested. The degree of viscosity produced was compared visually. Strains grew well at 25 °C–38 °C range, while L1-n1 and P3-n1 were able to tolerate a temperature range of 6 °C – 55 °C, pH range of 5.0 - 9.0 and NaCl levels up to 5% (w/v). C1-n1 was able to tolerate a pH range of 3.0 - 9.0 and NaCl levels up to 2.5% (w/v), while L2-n1 showed a growth only at neutral pH and a NaCl level of 0.01% (w/v). Also majority of strains were able to tolerate the heavy metals tested (Cu, Cd & Pb) at different concentrations. Strain L1-n1 showed an antibacterial activity against Staphylococcus aureus. All isolates formed nodules during the plant infectivity assays which were performed using their original plant host species confirming their identity as rhizobia. Plasmids were not observed in any of the isolates after performing the Eckhardt gel electrophoresis. According to the above results, these isolates may not be useful as biofertilizers, as they do not exhibit plant growth promoting traits satisfactorily. However further studies are required to determine their nodulation and nitrogen fixing efficiencies.
Determination of an eligible location for installation of a solar panel system in the University of Kelaniya using GIS
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Heshani, A.L.S.; Athukorala, S.M.W.; Leelarathna, W.D.S.R.; Weerasinghe, V.P.A.
According to the international energy agency, the role of renewables continue to increase in the electricity, heating and cooling and transport sectors. Newly develop technology in photovoltaic cells that have the potential to dramatically increase solar power generation in the next two decades. Being closer to the equator, Sri Lanka has a great opportunity to have solar energy throughout the year almost 5-6 hours per day. Sri Lankan power supply organizations are mainly depending on diesel, coal and hydro power. Still we do not have enough sources to supply electrical energy throughout the country. All the energy sources except hydro power are not considered as environmental friendly since they emit high amount of carbon to generate power. Being the first Green University in Sri Lanka, University of Kelaniya has initiated many approaches for energy conservation within the University. This study was carried out to find out the most suitable location within the University for installation of a solar panel system using ArcGIS software. For this, surface area of roof of buildings, height of buildings, elevation of the land, disturbance from other structures such as buildings and trees were selected. Map layers were created by using high resolution satellite image. Surface elevation profile was created by using available contour lines. Building layer was digitized from the satellite image using ArcGIS software. After overlaying all layers together suitable roofs were selected for the solar panels to install. In order to find possible energy in the area, meteorological data was collected including minimum and maximum atmospheric temperature, rainfall, and sunshine hours from Welisara meteorological station which is the nearest meteorological station to the University. The mean values of meteorological parameters obtained for the past 8 months were as follows; maximum atmospheric temperature of 28.28 0C and minimum of 26.02 0C, rainfall of 171.92 mm and sunshine hours were 7.6 hours. After selecting suitable buildings from the map, visual observation was done to calculate roof area of each building manually. The building with the highest surface area and minimum disturbance from adjacent structures was selected as the best suited location. The best suited location was selected and also it shows the highest monthly average consumption of electricity among other university buildings. Apart from that suitable lands also can be considered. But as the availability of lands in the university premises is a limited factor, priority was given to the rooves of the buildings. It is easy to make 3D view of the University by using 3D Analyst, if there is a higher resolution Digital Elevation Model (DEM). Roof structure and the shape can be used to maximize the efficiency of solar panels. GIS can be used as a supportive tool in optimization of determining the best suited location for the solar panel installation.
“Save me”: Alternative payment method for in-app purchases
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Choxmi, S.; Peter, S.
The mobile smart phone has become the most sought after technology tool, among the younger generation of the world. Sri Lanka is no exception with mobile penetration at more than 100% with growth of smart phone usage growing exponentially. Gaming with the aid of computers has become a billion dollar business and the wide usage of mobiles meant that a wider audience has now access to such tools. Companies are moving away from broad based advertising to more targeted direct advertising to capture market share. Use of mobile apps is widespread and the potential for companies to generate revenue streams by tapping into these applications have huge potential. The business strategy adopted by some developers is to offer the game for free while progress in levels of the game require in-app purchases to improve the gaming success and gain competitive advantage among players. In the perspective of the developers, in-app purchasing done by the gaming individuals is the main revenue stream. In developing countries like Sri Lanka, players of these games are reluctant or unable to spend money to purchase these inapps, since there is no financial benefit other than succeeding in the game. The other reason is that credit card details should be provided to purchase them. Most young people do not have or have access to credit card facilities. Thus, developers of game products are inhibited due to the lack of monetary incentive to build new gaming products and the players are inhibited by not being able to utilize the total advantages provided by the game. “Save – me” is a product designed to overcome these constraints by introducing an alternative method for payment and thus provide an incentive for mobile game developers to expand their market and increase their revenues, leading to the development of the information technology sector in the country. The current revenue models used by game developers include, selling the game for a fixed amount as a onetime fee, generating revenue from advertising while providing the game at no cost, and product or service providers financing the cost of the game through use of virtual coins. The models were evaluated using cost-benefit and sensitivity analysis. The latter was selected for its innovativeness and the ability to address the issue in a cost effective manner. The web portal solution includes three stakeholders. i.e. gamers, developers and manufacturers of goods and services targeting the gaming segment of the population. The process will commence with manufacturers / distributors assigning a discount to their products, in order to boost their revenue. Instead of giving customers the monetary discounts, the manufacturers will purchase virtual coins from “Save me”, and assign those coins to selected games on the portal. Customers who have registered on the portal, can earn these virtual coins instead of the discount, by progressing through the game and collecting these virtual coins. They can then exchange these virtual coins by going to their local supermarket which acts as a distributor and exchange the coins for the physical product that the manufacturer wants to promote. The game developers will be sharing the revenue via the purchases done by the players together with the portal owner.
An AHP approach to prioritize the distributor’s requirements while minimizing the transportation cost
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Madushika, I.K.; Wijayanayake, A.
Academic and corporate interest in Supply Chain Management (SCM) has risen considerably in recent years as SCM has emerged as one of the major areas for companies to gain a competitive advantage. Basically, the three fundamental stages of a Supply Chain (SC) are, procurement, production and distribution. Among these three stages, distribution plays a vital role as it directly impacts both the SC cost and customer experience. Many models have been developed in the past to minimize transportation cost under different constraints, as the main cost of logistics is transportation. In fact, when the organizations run on cost cutting approaches, not all the customers are satisfied when the demand surpasses the supply. Therefore, to retain the most important customers a proper mechanism is needed to prioritize them. Previous studies have been addressed different problems in logistics and improved models have been developed to maximize the service level and customer satisfaction but prioritization of customers is still a gray area which remains in the logistics literature. One of the main hurdles for distributors is handling situations, where the demand is higher than the supply and selected set of orders have to be delivered. Therefore, the main objective of the study is to identify the most important customers to be delivered first, from the distributor’s perspective while minimizing the cost of transportation. In this study, Analytic Hierarchy Process is used to identify the most important customers to the organization, under different criteria, defined by the distributor. All the criteria and alternatives were compared pair-wisely to calculate the overall importance of the alternatives. A mixed integer linear programing model has been developed with priority values in order to minimize the transportation cost. The proposed model will satisfy the needs of the important customers first and then the rest of the customers will be satisfied with the remaining quantities. When comparing the results of the developed model and ordinary transportation model, the transportation cost is higher in the developed model than the general transportation model. However, the satisfactory level of meeting the demands of the important customers is almost 100%. Therefore, this model is more appropriate for the firms who value customer needs more than minimizing the transportation cost.
Enumeration of yeast and mold in tea and herbs using different methods and culture media
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Jayashantha, E.T.; Asalaarachchi, G.; Abeygunawardena, S.I.
The International Standard Organization (ISO) has recommended the use of Dichloran 18% glycerol agar (DG-18) to enumerate yeast and mold in food (ISO 21527-2:2008) with reduced water activity (aw < 0.95). This ISO method uses the Surface Spread technique (SS-t). According to the ISO standard procedure, pour plate method is allowed to perform after a proper validation of results using the same medium. The objective of this study was to compare the Pour Plate technique (PPt) and spread plate technique using DG18 agar medium to enumerate yeast & mold in tea and herbs (e.g. lemongrass). The DG 18 agar medium was also compared with Yeast extract Dextrose Chloramphenicol (YDC) agar to enumerate these microorganisms. The tea samples and the herbs obtained from tea industry were used as the matrices for this study because these components have a water activity a less than <0.95. The sample preparation and the test were performed according to the ISO 21527-2:2008 standard procedures. Total of 20 samples of herbs and tea were used in this microbiological testing programme and the results were statistically analyzed using Paired-t test, with Minitab-14. The DG-18 medium gave average yeast and mold counts in tea samples as 2.58±0.42 CFU (log)/g in SS- technique whereas PP technique gave 0.41±0.08 CFU (log)/g. The fungal burden in herbs was 2.69 ±0.54 CFU (log)/g (SP-t) and 2.17 ±0.89 CFU (log)/g (PP-t). The YDC medium using pour plate technique gave average yeast and mold counts for tea and herb samples as 2.44 ±0.44 CFU (log)/g and 2.88 ±2 CFU (log)/g respectively. The DG-18 agar medium with the same technique gave 2.52±0.43 CFU (log)/g and 2.46±1.5 CFU (log)/g. The statistical analysis indicated that the results obtained either using two different media or using two different techniques with DG 18 medium were not significantly different.
Assessing potential biological hazards associated with Kelani River water using Nile tilapia (Oreochromis niloticus) as an aquatic model species
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ruvinda, K.M.S.; Pathiratne, A.
Kelani River receives complex mixtures of pollutants from diverse sources which include waste from industries, agriculture, domestic and municipal sources. However, scientifically based evidences on biological impacts associated with the Kelani River water are limited. Nile tilapia (Oreochromis niloticus) is a practically feasible aquatic model for toxicological assessments under tropical conditions. The present study assessed erythrocytic nuclear abnormalities (ENA), hepatic ethoxyresorufin O-deethylase (EROD) and hepatic glutathione S-transferase (GSTs) activities of Nile tilapia following exposure to selected surface water samples collected from the Kelani River and its tributaries in order to assess the potential biological impacts. Fingerlings of fish were exposed to surface water samples from an industrial effluent receiving canal (Menikagara ela; Site B), canal confluent (Site M), downstream of Kelani river at Sedawatta (contaminated with oil installation complex effluents and house hold waste; Site S) and up stream of Kelani river at Ruwanwella (reference site; Site R) and aged tap water (as controls) for 10 days under static renewal conditions. Physico-chemical parameters of exposed water were measured using standard analytical methods. Blood and liver samples of the exposed fish were collected from each treatment after 5 and 10 days of exposure, and ENA and EROD and GST tests were performed using standard methods. Water quality parameters indicated high levels of chemical oxygen demand, biochemical oxygen demand, total dissolved solid, salinity and conductivity and elevated levels of total phosphate content, nitrate content, heavy metal Cr, Cu and Pb levels in the water collected from the Sites B, M and S compared to tap water (P <0.05). Frequencies of total ENA were significantly higher in the fish exposed to water from the sites B, M and S compared those of the fish exposed to the tap water for 5 and 10 days. Blebbed and notched nuclei contributed mainly to the induction of total ENA than micronuclei and nuclear buds. Total number of nuclear abnormalities was elevated by the 10th day of exposure. Hepatic EROD and GST activities of the fish exposed to polluted water were not significantly different (P >0.05) from those of the fish exposed to tap water, but the enzyme activities were increased in each treatment at 10th day of exposure. Comparison of nuclear abnormalities and hepatic EROD & GST activities of O. niloticus together with physico-chemical analysis revealed that Sites B, M and S of Kelani River are contaminated with organic and inorganic xenobiotics, which may pose harmful cyto-genotoxic impacts on the feral fish populations.
Analysing mobility patterns of people to determine the best transportation method
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Senanayake, J.M.D.; Wijayanayake, W.M.J.I.
With the technological enhancements related to Internet, Wireless Communication, Big Data Analytics, Sensor-based Data, and Machine Learning; new paradigms are enabled for processing large amount of data which are collected from various sources. In the past decades, both coarse and fine-grained sensor data had been used to perform location-driven activity inference. In recent years, GPS phone and GPS enabled PDA become prevalent in people’s daily lives. With such devices people become more capable than ever of tracing their outdoor mobility and using locationbased applications. Based on the collected data from these GPS enabled devices with the help of IoT related to user mobility lots of research areas are opened. In this research the data related to user locations when users do any outdoor movements is collected using the mobile devices that are connected to the Internet and is mined using data mining techniques and come up with an algorithm to model & analyse those big data to identify mobility pattern, traffic prediction, transportation method satisfaction etc. The data for this research will be collected using a mobile application which has to be installed in smart devices like smart phones, tablet PCs etc. In this application the user has to enter the activity that he or she currently doing and the method of transportation & the users' opinion on the transportation method if he is doing some sort of travelling. The GPS coordinates (longitude & latitude) as GPS trajectories along with the time stamp and the date will be automatically acquired from the users' IoT device. A cloud based storage will be used to store collected data. Since the dataset is going to be a huge one, there can be data which contains outlier values due to the uncertainty of the mobile network coverage and the GPS coverage of the devices. Therefore, these data should be properly cleaned when doing data mining activities otherwise these data will lead to incorrect results such as wrong traffic prediction in certain places if several users are stuck in the same GPS coordinates for a while. Not only that but also when it comes to the user satisfaction, it might lead to generate incorrect outcome if the users in the sample will not enter their satisfaction accurately. This can be avoided by comparing cluster wise users with the consideration of the location and the transportation method. We can get the average opinion of the users and take it as the satisfaction of the transportation method in that cluster. Using the final results of this research the government can also be benefited if we selected the sample users well with mixing all the types of people and by providing necessary information for planning smart cities.
Electrodeposition of well-adhered CdTe thin films for solar cell applications
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Atapattu, H.Y.R.; de Silva, D.S.M.; Pathiratne, K.A.S.
Among the second generation thin film photovoltaics, CdS/CdTe based solar cell device is one of the leading contenders for large scale commercialization. Since the CdTe is the crucial absorber material of the foregoing device, it is essential to maintain a well-adhered CdTe layer to obtain high photovoltaic activities. If not, loosened CdTe layers with numerous pinholes can reduce the electrical, optical, structural and morphological properties of the material and hence extinguish the entire activities of CdS/CdTe solar cells. In the present study, an electrodeposition procedure was developed to fabricate welladherent CdTe layers to the substrate using the typical three electrode electrolytic cell. A fluorine doped tin oxide conducting glass substrate (7Ω/sq.) with dimensions of (1×3) cm2 was used as the working electrode in the cell. A saturated calomel electrode and a high purity graphite rod served as reference and counter electrodes respectively. All the electrodepositions were carried out using an aqueous solution containing 1.0 mol/L CdSO4, 1.0 mmol/L TeO2 and 5.5 mmol/L CdCl2. Based on the cyclic voltammetry studies and the stoichiometry of the proposed chemical reaction which forms CdTe material, the possible cathodic deposition potential (CDP) and pH ranges were identified to be in the ranges of 550-710 mV and 1.4-2.4 respectively. Henceforth, CdTe layers were electrodeposited at above mentioned conditions at temperature of 65 °C and subsequently annealed in air at 400 °C for 10 min. Thereafter, by considering the physical appearance of deposited CdTe layers and their adhesiveness upon a high pressure N2 flow, the feasible values for CDP and pH were found to be in the ranges of 590-660 mV and 2.0-2.4 respectively. To further fine-tune the values for CDP and pH, a series of CdTe layers were deposited at above feasible growth conditions and inspected for their electrical, optical, structural and morphological properties using the methods of photo-electrochemical cell, optical absorption spectroscopy, X-ray diffraction and scanning electron microscopy respectively. Results revealed that, the optimum CDP is in the range of 620-660 mV and pH is in the range of 2.1-2.3 to exhibit good photovoltaic qualities.
Predictive analytics for decision making: Human computer interaction perspective from online purchasing
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kiringoda, N.M.; Rupasinghe, T.D.
The internet-based technologies have influenced all parts of human lives within a short time. The internet is used for conducting commercial transactions electronically and it is the base of the concept called e-commerce. Most of the businesses have engaged in utilizing the Internet to sell their product and services. Hence, spend millions of dollars to create and maintain their corporate websites. The consumer behaviour in online shopping is continuously changing due to the personal characteristics of the shoppers as well as the environmental factors. The e-commerce based transactions are becoming increasingly popular and the number of consumers who interact with the e-commerce sites have been drastically increased along with the reviews they leave after purchases. This makes it difficult for potential customers to read, comprehend, and make sound decisions on individual purchases. Furthermore, makes even difficult task for the corporate entities to track their websites to manage customer opinions. Text mining is the process which explores, evaluates, and interprets data patterns by converting unstructured text data into more meaningful information. In this study, we address the aforementioned issues by proposing a Human Computer Interaction (HCI) enabled Naïve Bayes classification approach to categorize the online reviews of e-commerce websites. HCI factors such as; usability, simplicity, and accessibility are considered along with consumer reviews extracted from the attribute dictionaries such as stanford parser. The study has derived different data patterns from the text mining exercises which will be beneficial for predictive analytics from the customers’ as well as from the corporate standpoint for online purchases.
Isolation and identification of some members of skin flora
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Thushani, B.G.V.; Edirisinghe, E.A.A.D.
Skin is the largest organ of the human body and provides habitat for a diverse flora of microorganisms although it is an inhospitable place for many microorganisms because of the acidity and antimicrobial secretions of the body. An enhanced understanding of the skin microbiota is necessary to gain insight into microbial involvement in human skin disorders and to enable novel antimicrobial therapeutic approaches for treating them. Culture-based methods are essential in isolating and identifying viable cutaneous microorganisms such as bacteria and fungi. The main objective of this study was to isolate and identify normal flora of the skin by culture methods. Swab samples were taken from the side of the nose and elbow and were inoculated on Nutrient agar to obtain pure cultures. Identification was done by methods described in the “Cowan and Steel's Manual for the Identification of Medical Bacteria”. Some of these isolates were Gram-positive, non – motile cocci and some were Gramnegative, motile rods. Cellular arrangement of Gram-positive cocci was found to be as clusters and chain, but no spore former among isolates. Gram-positive, non - motile, oxidase negative, catalase positive and facultative anaerobic cocci were identified as Staphylococcus. Gram-positive, non – motile, oxidase negative, catalase negative and facultative anaerobic cocci were identified as Streptococcus. Pseudomonas isolates were Gram negative, rod – shaped, motile, oxidase positive, catalase positive aerobic bacteria. Biochemical identification process was extending up to the species level. Among the Staphylococcus isolates, there were Staphylococcus aureus and Staphylococcus epidermidis. These two isolates were differentiated by performing selected set of biochemical tests; Coagulase test, Mannitol fermentation on Mannitol salt agar and DNase reaction were major biochemical tests that were helped to identify species of Staphylococcus genus. Isolates belonged to the Genus Pseudomonas were confirmed by growing on a selective medium for Pseudomonas. This isolate showed fluorescence under UV light due to the production of the pigment flourescein when it was grown on King’s B medium. It produced green colour pigment on King’s A medium and peptone water, have the ability to hydrolyse Tween 80 and grow on MacConkey agar. The negative result in the egg – yolk reaction was helped to further confirmation of this isolate as Pseudomonas aeruginosa. β – haemolysis on blood agar, positive result for esculin hydrolysis and sensitivity to bacitracin were major characteristics to identify an isolate as Streptococcus pyogenes. Positive and negative controls were employed for the accurate determination of results. Therefore, it could be concluded, Staphylococcus aureus, Staphylococcus epidermidis, P. aeruginosa and Streptococcus pyogenes are some members of the human skin flora that can be isolated and identified using culture based methods. These isolated and identified bacteria were used to test the antimicrobial activity of an ayurvedic drug that is used to treat skin wounds and skin rashes.
Selective magnetic field localization for safety enhancement in wireless power transfer applications
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ranaweera, A.L.A.K.
During the last decade wireless power transfer (WPT) has been immerged as one of the rapidly growing area of research. Wide range of its commercial applications such as charging pads, are appearing in market today. The operating principle of WPT is based on resonant inductive coupling which use evanescent magnetic field patterns. However, inherent magnetic flux leakage in it makes concerns on human safety. Therefore, there is a higher demand for selective wireless power transfer where only the intended receiver location is powered. To that aim, a mechanism is needed to precisely focus the magnetic field into the receiver location. The currently available WPT applications lack the precise spatial control of magnetic field. Therefore, in this study, novel method of magnetic field localization is proposed to reduce the magnetic flux leakage into the surrounding area other than the intended receiver location. Several methods have been reported recently for light localization in the deep sub wavelength scale using the capabilities of metamaterials. Metamaterials are a kind of artificially designed material which provides unique and exotic electromagnetic properties such as negative refraction, evanescent wave amplification. Metamaterials usually studied under effective medium approach has previously been successfully utilized in several applications including superlensing, sub-wavelength imaging beyond classical diffraction limit and wireless power transfer. Metamaterials shown to exhibit the well known hybridization bandgap above its resonance arising from the Fano type interference between continuum of plane waves and locally resonating unit cells. By creating a local cavity within the hybridization bandgap, it is possible to localize the magnetic field into the cavity location. Using this property, we propose a method to precisely localize the magnetic field on to surface of the metamaterial where the cavity is created. We utilize active metasurface which can be externally controlled to realize a local cavity within the hybridization bandgap. The proposed metasurface is fabricated with standard PCB fabrication process and experimental investigation is carried out to obtain the spatial distribution of magnetic field. To obtain experimental results, we place the fabricated metasurface in between Tx and Rx of WPT system which is connected to two ports of vector network analyzer. We use small loop coil as receiver loop to make the measurements non-invasive. Spatial distribution of magnetic field is extracted from the measured scarring matrix parameters using the Keysight 5063A vector network analyzer. The results indicated that the magnetic field can be precisely localized to the intended location. We believe that this can be used to improve the safety of wireless power transfer applications.
Study on knowledge management practices in software development industry in Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Gunawardhana, A.; Wijayanayake, W.M.J.I.
In the information age with expanded global market, many organizations compete for higher profit margins. As a result, using previous knowledge for redesigning and integrating business processes to increase operational efficiencies has become a necessity. Furthermore, organizations can improve quality of products and services by collective body of knowledge offered by employees of these organizations. Software development process is a knowledge-intensive process. Therefore, with the increased complexity of Software Engineering (SE) project work, knowledge processes have led to a greater dependency upon solving problems. Software organizations gain local experience with the time by completing lots of SE project works, careful measurement of planned software activities, trial and error, feedback from customers and from the environment in general. However, for better implementation of Knowledge Management (KM) practices, organizations need to be supported by right kind of people, process and technology. Organization’s people, processes and technology will at all times are either enablers of, or barriers to, effective knowledge management. Therefore, it is very important to identify the barriers and remove them and build enablers which support the effective KM practice within the organization. This study is built around this people, process and technology model. Therefore, people, process, technology are independent variables and effectiveness of KM is the dependent variable. This study was undertaken to analyze key factors affecting to the effectiveness of KM, finding out the percentages of each people, process, and technology factors impact to the KM in software industry and as the main objective, study the current KM practices in Sri Lankan software development industry and find out the best KM practices. The study is descriptive in nature. Stratified sampling technique under probability sampling design will be used to select the samples. Primary data will be collected from the samples by administering a structured questionnaire. The data will be collected from small to large KM practicing companies. Correlation and coefficient analysis, multiple regression analysis and ANOVA will be carried out on the collected data to derive the findings. With the time by working on different projects, employees gather unique knowledge from their experience. The results of this study will help managers to facilitate adoption of KM and prioritizes its practices.