iPURSE 2023

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/33

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Demand estimation of household food waste: A case from Kurunegala district
(University of Peradeniya, Sri Lanka, 2023-09-20) Thilakarathna, G.D.S.; Weerasooriya, S.A.
Household food waste is driven by consumer habits and behavior. It differs with demographic, social, and economic factors. This study aims to determine whether household food waste is a luxury good and identify how demographic and socioeconomic factors affect household food waste. For this, a Quadratic Almost Ideal Demand System (QUAIDS) model was used, which is augmented with demographic, socioeconomic, and expenditure controls. Data were obtained in October 2022 through an online survey from 195 respondents living in the Kurunegala District of Sri Lanka. Data on food habits and quantity of food waste in food categories based on the consumption of most households in Sri Lanka, namely, rice, other cereals, pulses, fruits, vegetables, meat, fish, dairy products, eggs, and miscellaneous foods. Values (expenditure) on the waste of each food category were calculated by multiplying expenditure on each food category with the percentage of waste, and then expenditure share on each category of household food waste was obtained. The demand system estimation showed that all expenditure elasticities for all food waste categories as positive, indicating that they are normal goods. Food waste categories were identified as luxury goods or necessary goods. Waste of rice, other cereals, pulses, fruits, vegetables, and miscellaneous food in the household were necessary goods, while the waste of meat products, fish, dairy products, and eggs food categories were luxury goods. Expenditure share on household food waste differs with residence area. High- income group of households shows higher expenditure shares on food waste, lowest in the low-income group, and in between among middle-income households. Expenditure shares and expenditure elasticities vary with demographic, social, and economic factors. According to the study, most households practiced different management practices and they had positive attitudes toward minimizing household food waste.
Estimating the technical efficiency of small-scale inland fisheries: A case from Vavunikulam Tank
(University of Peradeniya, Sri Lanka, 2023-09-20) Nilusha, S.; Weerasooriya, S.A
The fisheries sector comprises coastal, offshore, and inland fisheries. Inland fisheries specifically involve the exploitation of fishery resources from inland water environments. Vavunikulam is one of the largest tanks in the Mullaitivu District, Northern Province, Sri Lanka, and holds immense potential for inland fishing. This study aims to determine the level of technical efficiency and identify factors affecting the technical efficiency of small-scale fishing households. This study also focuses on the role of the National Aquaculture Development Authority of Sri Lanka (NAQDA) and the fishing society in this context. Out of the 60 fishing households using the Vavunikulam tank, 50 fishermen were selected using a convenient sampling method. Data were collected with thoughtfully designed questionnaires. A Cobb-Douglas stochastic frontier approach with an inefficiency model was used to estimate the technical efficiency and identify the determinants of the efficiency of fishermen. The maximum likelihood parameter estimates showed that fishing output was significantly and positively correlated with the number of fishing gear used and the duration of fishing. This indicates that optimizing input usage can lead to increased fish output levels. The study found that 69.80% of the deviation of observed fishing output from frontier output was due to technical inefficiency. The estimated mean of technical efficiency of the sample fishermen was about 86%, suggesting that by efficiently utilizing existing resources, the technical efficiency could be enhanced by 14%. Further results showed that education level, experience, and income from other sources were found to have a negative and significant effect on technical inefficiency, and age was found to have a positive and significant effect on technical inefficiency of fishing output. Therefore, government and policymakers should take necessary actions and foster policies to improve the technical efficiency of fishermen through providing formal as well as informal education, training programs, and credit facilities.
Addressing information-related issues in Sri Lanka's smallholder plantation sector: a web-based approach (AGISSP)
(University of Peradeniya, Sri Lanka, 2023-09-20) Nimanthika, M.E.N.; Weerakkody, W.J.S.K.; Weerasinghe, K.S.; Jayathilake, H.A.C.K.
The advent of the digital revolution has sparked a remarkable transformation in information utilisation. With the widespread accessibility of the internet and mobile technologies, it allows people to access vast knowledge and connect effortlessly, leading to an era of efficient information utilisation. However, many developing countries, including Sri Lanka, have not fully harnessed these opportunities. Despite being vital for optimal agricultural production, timely and relevant information remains overlooked. The plantation sector, crucial to Sri Lanka's economy, is currently declining, necessitating innovative solutions for its revival. Therefore, this study aimed to identify information-related issues within the smallholder plantation sector in the Western Province, Sri Lanka. Additionally, it sought to design and develop a web- based system for plantation crops, addressing the identified issues effectively. A survey involving 134 smallholder plantation growers was conducted, gathering data through structured questionnaires via online and face-to-face methods. The analysis of the data led to the creation of a web-based agricultural information system, with its frontend designed using HTML and CSS, and the backend implemented with MySQL and PHP. Survey results emphasised the importance of information like suitable varieties, fertilisers, pests and diseases in their cultivation. A significant proportion of respondents agreed that an internet-based solution could efficiently and effectively provide agriculture-related information to farmers. The development of AGISSP (Agricultural Information Systems for Smallholder Planters), a web-based agricultural information system, aimed to address their information needs. AGISSP is a user- friendly platform that offers comprehensive information related to plantation crops, their best management practises, fertiliser recommendations, and pest and disease management. Over time, agricultural systems have proven successful, addressing challenges like climate change, food security, and sustainable farming. Their effectiveness highlights the need for ongoing research and development to further improve the agricultural sector.
Farmer's intention to engage in groundwater recharging and management practices: a case study from the Mottapeththewa cascade system
(University of Peradeniya, Sri Lanka, 2023-09-20) Weerasooriya, S.A.; Wanasekara, K.H.; Kumara, G.K.T.P.
The Mottapeththewa cascade system is located in the Galgamuwa area of the Kurunegala District. The objectives of this study are, to estimate the factors affecting the intention of farmers to engage in groundwater recharging and management practices and to estimate the factors affecting farmers’ engagement in groundwater recharging and management practices. A field survey was conducted using a questionnaire. The descriptive statistics indicate that more than half of the sample had training on groundwater recharging. The conceptual framework based on the Technology Acceptance Model consists of 7 constructs such as (i) result demonstrability, (ii) self-efficacy, (iii) perceived usefulness, (iv) perceived ease of use, (v) attitude, (vi) intention, and (vii) demographic factors. According to the results of the Structural Equation Model, result demonstrability and perceived usefulness have an indirect effect on intention (P<0.05) while attitude and perceived usefulness have a direct effect on intention (P<0.05). A probit model was conducted to find the factors affecting farmers’ engagement in groundwater recharging practices. The results revealed that percolation pits are affected by education, farming experience, land area, training on groundwater recharging, annual and perennial crop types, and home gardening (P<0.05). Constructing percolation wells is affected by the farming experience, land area, training, vegetables, and field crops (P<0.1). The practice of lock and spill drain is affected by home gardening, perennials, and manual irrigation (P<0.1). Home gardening, field crops, and manual irrigation affect practicing runoff water harvesting trenches (P<0.1). The practice of organic mulching is affected by education, annuals, and vegetable crop type (P<0.1). The findings of the study imply that farmers’ engagement in groundwater recharging practices is affected by different farm and demographic factors. Relevant authorities can use these findings for their further projects on groundwater recharging and awareness programs.
Prevalence of occupational hazards among paddy farmers and role of agricultural extension: a study in Horowpathana DS division, Anuradhapura District, Sri Lanka
(University of Peradeniya, Sri Lanka, 2023-09-20) Rathnayake, B.S.A.K.; Dissanayeke, U.I.; Rathnayake, S.J.
Occupational safety and health is a prime area of concern for international labour regulations. Different occupational safety and health issues could be evident among farmers. There are limited studies conducted in Sri Lanka from the perspective of occupational safety and health among farmers. A descriptive cross-sectional study was conducted to identify the prevalence and awareness of occupational hazards among paddy farmers in Horowpathana DS division, Anuradhapura district. Data were collected from five key informant interviews, two focus discussions with officers, a questionnaire survey on 300 paddy farmers, and an informal discussion with 20 paddy farmers and analyzed using qualitative and quantitative methods. More than half (62.1%) of the respondents were male, paddy farmers. The majority (32.6%) was in their middle age (42-52 years) with the mean age of 48 years. The majority (28.7%) had farming experience for 11-22 years and about 24.3% of respondents had more than 34 years of paddy farming experience. The average land area under paddy cultivation was 3.1 ha. and 91.3% of respondents were members of different farmer organizations. Different types of agricultural diseases such as leptospirosis (5.1%), kidney diseases (6.7%), muscular disorders (30.9%), and accidents such as agrochemical poisoning (5.1%), injuries (22.4%), wild elephant attacks (1.0%) and snake bites (8.4%) were prevalent in the area. Awareness of some occupational hazards was poor among respondents and extension officers. Therefore, improving awareness of occupational safety and health is needed, adopting a multi-institutional approach. Kanna meeting was identified as the most appropriate platform to conduct awareness programmes. Incorporating occupational safety and health into agricultural extension policies would be helpful to ensure farmers’ well-being.
Adsorption characteristics of ammonium onto rice husk biochar pyrolysed at different temperatures
(University of Peradeniya, Sri Lanka, 2023-09-20) Dharmakeerthi, R.S.; Jayarathna, M.K.N.W.; Igalavithana, A.D.
Low nitrogen use efficiency of added fertilizers is a great concern as it is less than 50% in most agro-ecosystems. Biochar (BC) has a massive micro pore structure, high surface area and surface charge which improve the soil nutrient adsorption. Nonetheless the pyrolysis conditions and type of feedstock determine the physicochemical properties of BC. The present study was conducted to study the ammonium (NH4 + ) adsorption of rice husk BC (RHB) produced at different pyrolysis temperatures (i.e., 300 °C, 500 °C and 600 °C) using a Down Draft Double Chamber (DDDC) pyrolyser (i.e., 500 °C) and a laboratory scale muffle furnace (i.e., 300 °C and 600 °C). Biochar were named as RHB_300, RHB_500, and RHB_600 and characterized. A batch sorption experiment was conducted to evaluate the NH4 + sorption on BC and sorption isotherms were fitted (i.e., Langmuir and Freundlich). The fixed carbon percentage was increased with increasing pyrolysis temperature and highest was observed in RBH_600. Therefore, it can exist in soil over a long period of time as an NH4 +adsorbent. The RHB_300 showed the highest NH4 + sorption capacity at pH7. Langmuir isotherm model was best fitted with the NH4 + sorption (R2=0.99) on RHB_300 and RHB_600, and RHB_500 was best fitted with Freundlich isotherm model (R2=0.97). The significantly higher ash content (i.e., 45%) in RHB_500 can be attributed to this deviation by increasing the BC surface heterogenity. Among the tested BCs for soil application aimed at enhancing nitrogen use efficiency, the RBH_300 stands out as the best performer as it exhibited significant NH4 + sorption capacity and high fixed carbon content.
Evaluating desirable traits of plant-inhabited burkholderia, pseudomonas and bacillusIsolates for bioremediation of crude-oil
(University of Peradeniya, Sri Lanka, 2023-09-20) De Costa, D.M.; Ehelepola, U.W.W.H.K.; Kalpage, C.S.
Microorganisms are capable of cleaning petroleum hydrocarbon- contaminated environments. In addition to the degrading ability of petroleum hydrocarbons, some microbes have emulsification ability. The present study screened local isolates of bacteria for bioremediation ability and evaluated the emulsification potential. Burkholderia isolates (i.e. A, B, D, E, and F), a Pseudomonas isolate (G), Bacillus megaterium, and Bacillus subtilis which were inhabitants of plant surfaces were used for the study. Crude oil degrading ability of the bacterial isolates was tested in Bushnell Hass medium (BHM) using crude oil (0.1% v/v) as the sole energy source and optical density (OD) at 600 nm was measured. The emulsifying potential of the isolates was evaluated by calculating an emulsification index (E-24). The test was performed twice using the culture supernatants of the bacterial isolates and percentage E-24 was calculated. All the isolates demonstrated a typical growth curve over a two-week period in BHM supplemented with 0.1% crude oil indicating their ability to use/metabolize crude oil as the sole energy source as they did not grow in BHM without crude oil. Among the isolates, the highest and lowest growth rates were reported by B. megaterium and Burkholderia isolate A, respectively in BHM with 0.1% crude oil. Burkholderia isolate F and Pseudomonas isolate (G) showed no emulsification ability in comparison to the negative control but the emulsification indices of the rest ranged from 20- 40%. The study identified five Burkholderia, one Pseudomonas, one Bacillus megaterium, and one Bacillus subtilis isolates which are inhabitants of plant surfaces as potential microbes that can be grown on crude oil as the sole carbon source. Except for two tested isolates (F and G), the rest demonstrated emulsification ability. Results revealed the potential of using all the tested bacterial isolates, with or without the emulsification ability for the bioremediation of crude oil.
Evaluating a consortium of rhizospheric actinomycetes for plant growth promotion ability in rice
(University of Peradeniya, Sri Lanka, 2023-09-20) De Costa, D.M.; Perera, H.D.D.; Perera, K.A.N.C.; Dandeniya, W.S.
Actinomycetes possess mechanisms to promote growth and mitigate biotic and abiotic stresses of plants. The present study evaluated a consortium of actinomycetes for its growth promotion ability in rice aiming to minimize the inorganic fertilizer usage in paddy cultivation. Ten rhizospheric actinomycete isolates, confirmed for their nitrogen fixing and phosphate solubilizing ability in vitro were tested on rice (var. Bg 360). The treatments were: no Nitrogen (N) and Phosphorus (P) fertilizer in inorganic or alternative form (T1), N and P inorganic fertilizer as recommended by the Department of Agriculture (DoA) (T2), 50% reduction of DoA recommended N and P fertilizer with the actinomycete consortium (T3) and only the actinomycete consortium (T4). Every treatment received the DoA recommended potassium dosage. A pot experiment was conducted using 5 L capacity pots having ten replicates/treatment according to a complete randomized design. Number of tillers/hill, % chlorotic leaves/hill, % heading- initiated tillers were recorded and root length, volume, and dry weight were measured. Incidence of sheath rot, the only disease observed was quantified. The % heading-initiated tillers, % chlorotic leaves, root volume and root dry weight were significantly differed among the treatments (p<0.05). T1 plants showed the highest % of chlorotic leaves but that percentage was significantly lower in the rest of the treatments. Root volume and root dry weight reported by the T3 plants were on par with those received the N and P inorganic fertilizer at DoA recommendation (T2). T3-treated plants reported a significantly higher % of heading-initiated tillers and a significantly lower sheath rot incidence, compared to the other treatments. The consortium introduced in the present study has the potential to reduce the recommended rates of inorganic N and P fertilizer by 50% without significantly affecting the tested parameters and reducing sheath rot incidence.
Variation of diversity and abundance of insects associated with ground canopy in home gardens in Matale District, Sri Lanka
(University of Peradeniya, Sri Lanka, 2023-09-20) Warnasooriya, P.G.A.S.; Hemachandra, K.S.
Insects play a crucial role for the sustainability of the homegarden ecosystem particularly pollination, predation and parasitization. The objective of this study was to assess diversity of insects in relation to the ecological zone, and homegarden diversity. Homegardens (25) were selected in Matale districts covering five ecological zones. Homegardens represent three levels of diversity index, based on five socioeconomic, and biological parameters. Insects associated with ground level plant canopy were sampled using a sweep net (20 sweeps/sample) and sorted them and classified into orders and families. Of the 25 samples, 1793 insects and 193 spiders were found. Insects were in Orders: Hemiptera, Hymenoptera, Diptera, Coleoptera, Orthoptera and Lepidoptera in descending order of abundance. Hemipterans belonged to 18 families: Cicadellidae (49%), Rhyparochromidae (27%), Aphididae (9%), and Pentatomidae (6%). Dipterans belonged to 19 families: Drosophilidae (35%), Agromyzidae (23%) and Lauxaniidae (12%). Hymenopterans belonged to 13 families: Formicidae (59%), Eulophidae (15%), Braconidae (9%) and Platygasteridae (5%). Hemipteran number varied significantly (p<0.0.5) among homegardens, ecological zones, and homegarden diversity index (HGDI). Hymenopteran number per homegarden did not vary significantly; it significantly (p<0.0.5) varied with ecological, and homegarden diversity index. Number of dipterans significantly varied (p<0.0.5) among homegardens, ecological zones, and HGDI. The highest mean insect count per ecological zone was in DL1b (91.5±23) followed by WM3b (81.5±24), IM3b (72.7±16.8) and IM3a (69.5±37). The data revealed that a diverse group of insects was associated with the vegetation of home gardens. The diversity and abundance varied with the ecological zones and HGDI. The diverse nature of the home garden also affects associated insect diversity; therefore, home gardening practices should be planned with due consideration of insect conservation.
Effect of photobacterium damselae subsp. damselae on behaviour and standard metabolic rate of Western pygmy perch (Nannoperca vittata)
(University of Peradeniya, Sri Lanka, 2023-09-20) Pathirana, N.U.K.; Beatty, S.; Gleiss, A.; Lymbery, A. J.
Infection is often been associated with changes in host metabolic rate and behavior. Behavioral changes, particularly those relating to increased activity and boldness, have frequently been attributed to adaptive host manipulation by the parasite, but could also result from the host's response to pathology or as a non-adaptive side effect of infection. In this study, I exposed a freshwater fish (64 fish), western pygmy perch (Nannoperca vittata), to a sub-lethal concentration (1x106 cfu/ml) of a bacterial parasite (Photobacterium damselae subsp. damselae) for 6 hours, and measured the standard metabolic rate (SMR), the activity trait track length (TL), and the boldness traits time to emergence (ET) and time spent in a risky zone (RZ) (with 1-week intervals in between each time point). Infected fish (13 of 64 fish) that were exposed to P. damselae subsp. damselae died or were euthanised because of signs of infection such as ulcerated lesions or haemorrhages. The effect of P. damselae subsp. damselae challenge on the metabolic rate and behaviour of N. vittata was studied using generalised linear mixed models. For all attributes, the interaction between time-point and treatment was significant, with bacterial challenge boosting fish SMR, activity, and boldness. The standard metabolic rate of challenge-exposed fish remained high throughout the post- challenge period (3 weeks), although behavioural abnormalities were temporary, returning to pre-challenge values after two weeks. I hypothesize that changes in SMR and behaviour in infected fish result from a greater need for energy, either (or both) as a result of immune activation or compensatory growth.
Climate resilient crop varieties in Sri Lanka for enhancing food security: compilation of literature
(University of Peradeniya, Sri Lanka, 2023-09-20) Attygalle, S.U.
Climate change is affecting the consistency of crop production and one of the main challenges to achieve food security. Cultivation of climate resilient crop varieties has been identified as an effective solution in combating this challenge globally as well as locally. In Sri Lanka, there are many researchers and institutions involved in developing climate resilient crop varieties, yet there are inefficiencies in applying these findings to the practical context. In order to enable the efficient utilization of these crop varieties towards establishment of climate resilient food systems, it is important to collect and compile the relevant research findings that have been made so far. Related to this objective, research studies regarding climate resilient crop varieties were referred and the findings were compiled into an excel data base. Data collection was done through the internet, published journal articles, conference proceedings, etc. and contacting and referring to reports of research institutions that conduct relevant research. Information related to approximately 70 crop varieties those were grouped under 6 main crop categories namely paddy, fruits, vegetables, other field crops, tea, and other crops, based on the tolerance under drought, salinity, and submergence. Compilation of these findings will facilitate knowledge dissemination programs and easy access of this information by the farmers. It was noted that identification of salinity tolerant varieties has not been paid much attention to hence can be considered as a new research direction. Identification of climate resilient varieties of many commercially valuable crops have not been done yet, which should be given more consideration in the process of enhancing food security through climate resilient crop systems.
Commercialization and collaboration as smart-KPIs of a performance measurement framework to assess research on the commercial agriculture sector in Sri Lanka
(University of Peradeniya, Sri Lanka, 2023-09-20) Abeysiriwardana, P.C.; Jayasinghe-Mudalige, U.K.
Unending pressures on the research institutions by regulators to alter their research agenda to guarantee “more quality food from fewer resources” is ‘justified’ on the grounds of an ever-increasing population, emerging environmental challenges, and numerous other socio-economic situations faced by the nation. In the context of the commercial agriculture (CA) sector, these warrants ‘commercialization of research’ to induce more ‘collaborations’ between the institutes and industry to produce more society-friendly agriculture technologies. Thus, this research was directed, first, to determine how terms such as commercialization and collaboration were characterized by these CA-based research institutes, and then, to establish a performance measurement framework (PMF) that defines a set of key performance indicators (KPIs) to work in these regards. A systematic literature review facilitated the identification and collation of the information on PMF and KPIs (Phase I) followed by contact of the leaders in upper echelons (n=32) affiliated with leading research institutes work on CA by way of in-person interviews facilitated by a pre-piloted interview guide comprised of 15 probing questions (Phase II). Thematic Models produced through the MAXQDA Software were employed to converge leaders' perspectives into five major themes, namely 1. Research commercialization (R-Com), 2. Research collaboration (R-Col), 3. Research for society, 4. Institutional management and 5. Technology-integrated systems. The organizational benefits gained from a well-thought-out PMF comprised of smart KPIs (e.g., R-Com and R-Col) and their interactive effects were well accentuated. The analytical tools provided by the software (e.g., Code-Maps) were methodically used to build up these frameworks. The research outputs generated using real-time data-driven performance management based on KPIs will inevitably help to work out those modifications made to the research agenda in CA effectively.
Implementing an intrusion detection system for software defined networks using artificial intelligence
(University of Peradeniya, Sri Lanka, 2023-09-20) Dissanayaka, M.B.; Ihalagedara, S.B.; Koswaththa, M.; Senewirathna, S.; Udunuwara, A.
This study presents an artificial intelligence (AI) based innovative approach for an Intrusion Detection System (IDS) within a Software-Defined Networking (SDN) environment. The research involves testing and identifying the most effective algorithm of machine learning and deep learning, specifically XGBoost, Logistic Regression, LightGBM, and Artificial Neural Network (ANN), for intrusion detection. The methodology consists of creating a virtual SDN using Mininet, a virtual network emulator package, with five hosts and three switches to emulate real-world network scenarios. The OpenDaylight SDN controller is integrated into this network, facilitating seamless communication and control. Rest API and Wireshark tool are used to control the SDN controller and monitor the traffic of the network. Learning models are integrated into the SDN controller to monitor and analyze network traffic effectively and detect the attack types of DoS, DDoS, BOTNET, BFA, Probe, U2R, and Web-attack with a minimum false positive rate. We have used a publicly available SDN intrusion detection dataset to train these learning models. Hyperparameter tuning is carried out to determine the optimal conditions of each learning model and comprehensive performance comparison is carried out using accuracy, precision, recall, and F1-score. At model training, the highest accuracy of 99.9% was achieved through XGBoost algorithm while ANN with ten layers followed closely with an accuracy of 99.26%. These findings were further validated through the emulated SDN network. Our finding showed that the proposed models can successfully prevent a DDoS attack through the integration of the SDN controller and the machine learning model. These observations demonstrate the significant potential of machine learning and deep learning techniques for effectively coping with cyberattacks and improving cybersecurity strategies. In conclusion, this study presents a promising approach to enhance cybersecurity in SDN networks through AI approaches.
New approach to problems with one-dimensional bin packing
(University of Peradeniya, Sri Lanka, 2023-09-20) Jayawardana, G.K.G.S.K.; Ekanayake, E.M.U.S.B.
The Bin Packing Problem is a well-known optimization problem that is renowned for its applicability and complexity. It belongs to a special class of problems called NP-hard and entails trying to fit a set of items of varying sizes inside fixed-size containers while attempting to minimize the number of containers needed to fit the maximum number of items. The dimensions in bin packing problems refer to the number of characteristics or attributes used to describe the items and bins. Bin packing problems can be classified as One-Dimensional, Two-Dimensional, or Three-Dimensional depending on the dimensions. Among these, the One-Dimensional Bin-Packing Problem is one of the best- known optimization problems, and it has a significant number of applications. In order to pack all the products while keeping the bin capacity in mind, the challenge calls for determining the bare minimum number of bins. In this study presents a new algorithm for the ODBPP and provides comparative examples with Heuristic algorithms such as Next- Fit, First-Fit, Best-Fit, Worst-Fit, First Fit Decreasing and Best Fit Decreasing. These Heuristic algorithm techniques aim to strike a balance between computational complexity and solution quality. Through extensive computational experiments, it demonstrates superior performance in terms of the number of bins used and packing efficiency compared to other algorithms and the optimal solution. The objective is to minimize the number of bins used, thus maximizing space utilization and reducing resource waste. This algorithm contributes to the field of bin packing and provides a valuable tool for optimizing resource allocation and minimizing waste in practical applications.
A method of optimal homotopy analysis for solutions of boundary layer convection heat transfer of high-speed flow over a flat plate
(University of Peradeniya, Sri Lanka, 2023-09-20) De Silva, B.S.K.; Dewasurendra, M.T.M.
The present study addresses the intricate problem of boundary layer convection heat transfer in high-speed flow over a flat plate. The governing continuity and Navier-Stokes equations are considered under boundary layer assumptions and constant property assumptions. By introducing dimensionless variables, the equations are transformed into a coupled system, facilitating analysis. The goal of the research is to employ the Basic Optimal Homotopy Analysis Method (OHAM) to solve these equations and analyze heat transfer characteristics. OHAM, rooted in topology and geometry concepts, constructs linear operators, initial approximations, and deformation equations. The introduced parameter ħ is optimized using step-by-step optimization to minimize residual error, yielding accurate solutions satisfying initial and boundary conditions. Results demonstrate the accuracy of the approach, yielding higher-order approximations with minimal errors. Employing this approach, a 10th-order approximate solution is obtained, where errors are confined to third-order approximations. The presented results are consistent with the Mathematica package BVPH 2.0 developed by Liao. The presented figures illustrate velocity and temperature profiles, while a comparative table showcases the effectiveness of the method under different parameter sets. This study contributes to understanding complex convection heat transfer phenomena in high-speed flow scenarios. The proposed OHAM offers exceptional accuracy, making it a powerful tool for solving nonlinear systems in various fluid dynamics problems. The approach can be effectively employed for solving boundary layer convection heat transfer problems in high-speed flow.
A SEIR model for spread of hand, foot, and mouth disease
(University of Peradeniya, Sri Lanka, 2023-09-20) Rathnayake, R.M.M.L.; De Silva, T.H.K.R
Hand, foot, and mouth disease (HFMD) is an infection disease affecting tropical and subtropical regions worldwide. There are no vaccinations or antiviral medications available that target HFMD. In this study, an existing mathematical model is modified. The parameters which are used in this modified SEIR model are taken from previous studies in similar environments. The new mathematical model is proposed to calculate the transmission probability of two genders, and investigate the effect of indirect transmission from contaminated environments. Moreover, modified SEIR model is fitted to the real data on the number of infected children (under 14 years old) in 2020. Then some of the parameters that produce the best fit to the real data are estimated. In our results we can see that , which means the disease infected boys more than girls. The parameters and are much less than the rate , which means that the loss of viruses due to individuals taking out is much less that the loss due to clearance. Throughout this results we can see that effect of indirect transmission has two sides, threshold amount of hand, foot, and mouth disease is very small, or indirect transmission is not effected of transmission of the disease as we thought.
Choice of the inverse linear mapping in the method of directly defining the inverse mapping for inhomogeneous heat and advection problems
(University of Peradeniya, Sri Lanka, 2023-09-20) Sahabandu, C.W.; Dewasurendra, M.
Semi-analytical methods for solving nonlinear partial differential equations (PDEs) combine aspects of both analytical and numerical techniques. Unlike linear PDEs, which can be more straightforwardly solved using the separation of variables and superposition principles, nonlinear PDEs involve terms with nonlinear dependencies, making them significantly more complex to handle. The key to the analytical method lies in employing techniques like perturbation methods, similarity transformations, and integral transformations such as Fourier and Laplace transform to simplify the equations. These techniques often lead to obtaining exact solutions or approximations that provide valuable insights into the behavior of the system. However, due to the intricate nature of nonlinear PDEs, the analytical method may not always be applicable, and in these cases, numerical methods or approximate techniques become necessary. The Method of Directly Defining the inverse Mapping (MDDiM) is a semi-analytical method for obtaining approximate solutions for complicated nonlinear PDEs without using any kind of transformation. In this study, we explore different inverse linear mappings in order to determine the optimal inverse linear mapping that allows accuracy just after a few terms are evaluated by applying MDDiM to the inhomogeneous heat and advection problems. Additionally, we optimize the convergence control parameter by constructing an optimum control problem for minimizing the accumulated L2-norm of the squared residual errors using directed sum. This approach is far easier to compute than the square integrals of an infinite domain. By computing three-term optimal approximate solutions and comparing them with the exact solutions, we were able to choose the better inverse linear mapping for these two inhomogeneous PDEs. We can conclude that choosing a better inverse linear mapping leads to a more accurate solution in MDDiM.
Graph labeling and harmonies: odd and even labeling of star graphs
(University of Peradeniya, Sri Lanka, 2023-09-20) Dilshan, M.M.C; Perera, A.A.I
This research paper delves into the realm of graph theory, focusing on the concept of odd and even harmonies labeling within the framework of star graphs. The star graph family, characterized by a central vertex connected to peripheral vertices resembling a star's shape, serves as the primary subject of exploration. Harmonies labeling, an intriguing concept, involves assigning labels to graph vertices and edges following specific rules. A graph is considered harmonies if an injective function can be established between its vertex set and the integers modulo q (where q represents the number of edges), while ensuring distinct edge labels. This paper introduces the notions of odd and even harmonies labeling. In the odd harmonies scenario, each vertex is assigned a distinct even number from 0 to 2q-1. Notably, the sum of labels on adjacent vertices results in a unique odd number between 1 and 2q-1. Conversely, the even harmonies scenario assigns even labels to vertices within the same range, yielding a unique even sum for adjacent vertices. Extending Rosenfeld's 1979 work on odd harmonies labeling, this study explores both odd and even cases. The inherent properties of star graphs make them an ideal focus. As bipartite graphs, they naturally divide vertices into two sets, with connections exclusively between sets. Additionally, star graphs exhibit planar attributes, allowing representation on a flat surface without edge crossings. In summary, this research enriches graph theory by investigating odd and even harmonies labeling in the context of star graphs. By capitalizing on the unique properties of star graphs, this study advances our understanding of the intricate relationship between graph structures and harmonies labeling, encompassing both odd and even scenarios.
Investigating the development of Mathematics teachers’ pedagogical content knowledge for teaching Algebra: A professional development program
(University of Peradeniya, Sri Lanka, 2023-09-20) Rupasinghe, D.D.; Vitharana, P. R. K. A.; Amarasinghe, A. K.
This study aims to examine the success of Professional Development (PD) program for developing the secondary level mathematics teachers’ pedagogical content knowledge (PCK) in teaching algebra. The approach used is a mixed methods case study. The PD program was introduced to twenty (N=20) in-service mathematics teachers. The program included three stages based on its content. The nature of algebra, psychological foundation of teaching algebra and algebraic thinking were the components of the program. This PD program was conducted for two months continuously. The workshops included discussions and group activities. The participants’ existing experiences were used to fine- tune the workshop objectives. A pre-test, post-test and interviews were conducted to collect data. A paired sample t-test was used to analyze the pre and post-test marks while thematic approach was used to analyze qualitative data collected from interviews. The results revealed that the mean values of the pre-test and the post-test were 31.10 and 65.60 for valid 20 of data for both tests respectively. It indicates an appreciable success of the PD program. A considerable variability was found with a standard deviation between 10.252 and 4.012. The result of the paired sample t-test was 0.345, which indicates a positive correlation between the pre-test marks and the post-test marks at the 5% significant level and the p-value was less than 0.05. Therefore, it is observed that the PD program had considerably supported the development of the teachers’ PCK in teaching algebra. Interview results showed that teachers had acknowledged the abstract nature of algebra, selecting appropriate teaching strategies and designing creative activities with the help of improved algebraic thinking in them. The participants accepted that they have already applied less productive activities for teaching algebra. They asserted the lack of awareness of algebraic thinking as the cause. Hence, this study recommends similar PD programs for mathematics teachers.
A genetic algorithm to solve the integrated vehicle routing and vehicle sequencing problem with a single-door depot
(University of Peradeniya, Sri Lanka, 2023-09-20) Gnanapragasam, S.R.; Daundasekera, W.B.
Vehicle Routing Problem (VRP) is a well-known combinatorial optimization problem. In the case of single-door at the depot to enter, vehicles have to wait in the parking yard until they get their turn to unload their accumulated products. This waiting creates additional transportation cost and therefore, this idle time of each vehicle in the parking needs to be reduced. A proper mechanism to sequence the routed vehicles to the door is essential. Therefore the objective of this study is to test the compatibility of the developed model to the integrated VRP and Sequencing Vehicles (VRP&SV) to a single-door depot problem and propose a Genetic Algorithm (GA) to solve it. In the proposed GA, tournament selection, order crossover and swap mutation are chosen as the best combination of the operators for the robustness of the algorithm by employing the Taguchi method. The accuracy of GA is tested using the Branch and Bound (BB) algorithm. When the vehicles return to the depot, after serving the suppliers, the sequencing those vehicles to the door at depot is purely based on the principle of first come first serve basis. The factors of the total cost of VRP&SV are due to travelling between suppliers, preparation to load the quantities and loading them at suppliers, vehicle waiting at the parking yard, vehicle changeover to the door and unloading the accumulated quantities by vehicles. The results of small-scale instances not only confirm the feasibility of the proposed GA to solve the integrated VRP&SV but also reveals that the exact optimal solution can be reached by GA in less than 5 seconds even to the instance with 100 suppliers. Therefore, it can be concluded that the applicability of the integrated problem is confirmed. Further, it is recommended that the proposed GA can be employed at last time planning of VRP&SV models.

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