Browsing by Author "Hemachandra, K"

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3D full-field deformation measurement using stereo vision
(IEEE, 2022-07) Sarma, LS; Mallikarachchi, C; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Measuring 3D deformation and strain are crucial parameters in structural engineering applications both at the construction and operational stages. Precise 3D full-field measurements are useful in structural optimization, damage detection and retrofitting. Digital Image Correlation is a non-contact optic-based measurement technique that is proven to be an ideal candidate in this regard. It has the potential to become a cheap, simple, and precise solution for deformation measurement. However, the currently available Digital Image Correlation measuring systems require expensive dedicated software packages and physical resources which are difficult to access. Therefore, there is a need to develop a cost-effective measuring technique to effectively use it in the local context. This research focuses on the development and validation of a precise non-contact-based deformation measurement technique. In the proposed method, 3D full-field deformation of the deforming object is measured by processing stereo photographs taken with commonly available digital cameras using the image processing toolbox available in the MATLAB commercial package. Further, the proposed method is enhanced by developing it as a standalone application, which can be installed and conveniently used by any technician. Capability of using the developed application in common civil engineering laboratory experiments has been demonstrated.
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3d modeling and visualization of archaeological sites using modern engineering tools to promote tourism in Sri Lanka
(IEEE, 2023-12-09) Kodagoda, G; Wijesinghe, WHMCM; Illangarathna, ANL; Peiris, MDCD; Soysa, HSA; Virudake, PWS; Gunathilaka, HHC; Jayalath, JPME; Jayasinghe, YASS; Isuranda, NW; Jayasooriya, N; Kularathna, AHTS; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
The development of technology has paved the way to apply modern engineering tools in interdisciplinary perspectives. As a country relying heavily on tourism, the ancient heritage of Sri Lanka has its unique features, though it has not been well presented to the world of tourism. Thus, there exists a research gap in reaching out to the world, where the solution lies in collaborating among the fields of Engineering, Archeology and Tourism. The aim of the research is to reduce this gap in visualization of archaeological sites in Sri Lanka integrating modern engineering tools. The methodology involved site visits for physical data collection, drone mappings and 3D scanning. The obtained data is digitized using suitable mapping techniques. The digitized data is used for 3D model creation and visualization which involves steps of platform selection, texturing and rendering with the aid of Virtual Reality and Augmented Reality Techniques. The established framework is applied to two case studies; Thuparamaya Circular Relic House and Jethawanaramaya Image House. With the successful validation of the developed framework for the two case studies, it can be concluded that the developed framework can be used at other ancient archeological sites to promote tourism in Sri Lanka.
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Active and passive based hybrid cell balancing approach to series connected lithium-ion battery pack
(IEEE, 2022-07) Ekanayake, EMAGNC; Hemapala, KTMU; Jayathunga, U; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Lithium-ion battery (LiB) technology is extensively used in energy storage systems (ESS), electric vehicles, and portable devices. Optimal cell balancing techniques for a battery management system are essential for the operation of the Li Battery. This paper proposes a new passive and active-based hybrid cell balancing technique integrating switched resistor balancing technique and switched capacitor balancing technique to achieve less balancing time and less power dissipation with simple control and hardware. The proposed system has been mathematically modeled and simulated, and the results show a 30% increase in the balancing time compared to the conventional capacitive balancing technique. Also, the control algorithm can adaptively operate to achieve better performance of the circuit. The simulation is done in the MATLAB Simulink environment.
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Activity Participation Patterns of Individuals in Sri Lanka
(IEEE, 2021-07) Malshan, TMP; De Silva, GLDI; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Activity-based models are replacing commonly used traditional four-step models due to their high temporal and spatial resolution, integrity, interdependency, and behavioural basis. The foundation of an activity-based model is the activity participation pattern of an individual in the study area considered. This paper uses the time use survey data, collected by the Department of Census and Statistics and analyses them as the first step of building an activity-based model for Sri Lanka. Variations on weekday and weekend activity patterns were analysed separately. Since they are considerably different, the focus was on weekday activity participation patterns. The differences in activity participation patterns across gender, age, and geographical location were identified which are useful when building an activity-based model for Sri Lanka.
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Adaptive droop controller for energy management of islanded ac microgrids
(IEEE, 2023-12-09) Ediriweera, WEPS; Lidula, NWA; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Distribution feeders with high penetration of renewable power generation can be converted into microgrids for providing more quality power with increased reliability. Virtual synchronous inertia is used to increase the inertia of inverter-based microgrids to provide the same performance as synchronous generators. Frequency stability and power sharing among the distributed energy resources of islanded microgrids would be challenging due to poor transient response with droop controllers and inaccurate selection of droop values. This article proposes an adaptive droop controller for a microgrid in islanded operation that has several distributed energy resources including solar PV, diesel generator, and energy storage. Droop values, and reference values in the droop characteristics curve are decided based on the severity of the frequency disturbance and the state of charge level of the energy storage. The performance of the proposed droop controller is verified using a radial-connected microgrid derived based on a real distribution system. The results illustrate that during a disturbance, the proposed adaptive droop controller can slightly boost the diesel generator's output power with a minimum loss of charge of the energy storage.
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An adaptive yolo model for detection of faulty insulators in power transmission network using unmanned aerial vehicle
(IEEE, 2023-12-09) Ahnaf Shihab, ULM; Apsaan, MTMS; Fayas Ahamed, MH; Razeeya, MRE; Juhaniya, AIS; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Effective monitoring and problem detection are thought necessary for assuring continuous power supply. This study developed a machine learning approach to detect and diagnose insulator failures in power transmission lines by analyzing photos of cracked, polluted, and flash-overed insulators recorded using a drone. Through numerous rounds of the object recognition model YOLO (You Only Look Once), a diverse dataset of power transmission line photos was used to train and compare the performance of an enhanced YOLOv8x model versus YOLOv5n, YOLOv5x, YOLOv7, YOLOv7x, and YOLOv8n. Furthermore, approaches such as transfer learning and augmentation have been used to improve the model’s performance. The YOLOv8x model outperformed the other YOLO models tested, with an accuracy of 0.94, recall of 0.934, and Mean Average Precision (mAP) at 0.5 of 0.944 for insulator failure detection. The suggested fault detection machine learning approach combined with a dronebased system provides an adaptive fault monitoring system with high precision and low cost.
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Adversarial learning to improve question image embedding in medical visual question answering
(IEEE, 2022-07) Silva, K; Maheepala, T; Tharaka, K; Ambegoda, TD; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Visual Question Answering (VQA) is a computer vision task in which a system produces an accurate answer to a given image and a question that is relevant to the image. Medical VQA can be considered as a subfield of general VQA, which focuses on images and questions in the medical domain. The VQA model’s most crucial task is to learn the question-image joint representation to reflect the information related to the correct answer. Medical VQA remains a difficult task due to the ineffectiveness of question-image embeddings, despite recent research on general VQA models finding significant progress. To address this problem, we propose a new method for training VQA models that utilizes adversarial learning to improve the question-image embedding and illustrate how this embedding can be used as the ideal embedding for answer inference. For adversarial learning, we use two embedding generators (question–image embedding and a question-answer embedding generator) and a discriminator to differentiate the two embeddings. The questionanswer embedding is used as the ideal embedding and the question-image embedding is improved in reference to that. The experiment results indicate that pre-training the question-image embedding generation module using adversarial learning improves overall performance, implying the effectiveness of the proposed method.
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AHP analysis to evaluate challenging factors affecting border crossing point’s operation efficiency in Mongolia
(IEEE, 2023-12-09) Erdene, JJ; Perera, KPDF; Kazushi, S; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
This research uses the Analytic Hierarchy Process method to identify key factors affecting border port operations in landlocked Mongolia. Factors include transportation, government policy, procedure, capacity building, and information technology. The AHP method calculates influencing weights and surveys experts to determine priority factors and identify areas for improvement to facilitate international trade.
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An alternative method to reduce the construction cost and the reinforcement usage of the rigid pavement near the toll plaza in expressways.
(IEEE, 2022-07) Kasthurirathne, H; Edirisooriya, UJW; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
In expressways, a toll plaza structure is a conspicuous structure, where vehicles frequently brake and accelerate within a small distance. As a result, the pavement deteriorates at a higher rate compared to normal bituminous pavement. Hence, toll lanes near toll plazas are constructed as heavy reinforced concrete rigid pavements. In Sri Lanka, the same technique is used for rigid pavements near expressway toll plaza structures. Due to the high cost of this method, the objective of this research is to present a cost-effective way with acceptable efficiency by comparing methods and technologies that other countries use to construct rigid pavement in toll lanes. To achieve this objective, the used design methods and the material cost of the ColomboKatunayake expressway at Peliyagoda and Seeduwa toll entrances, Dambokka and Kurunegala toll entrances in the Northern expressway are discussed in this study. The study revealed that the replacement of reinforced concrete pavements in the above toll gates with Ultra-thin continuously reinforced concrete pavement can decrease the material cost by 7.97% at Peliyagoda, 36.08% at Seeduwa, 5.66% at Dambokka, and 5.48% at Kurunegala. Used pavement design and the proposed ultra-thin continuously reinforced concrete pavement are analyzed using the Finite Element Analysis (FEA) method through ABAQUS 2020 software. Obtained results indicated that it is more economical to use an ultra-thin continuously concrete pavement with steel fiber than the currently used method.
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Analysis of flow induced vibration of high head francis turbine
(IEEE, 2023-12-09) Chandima, GPR; Miyanawala, TP; Nissanka, ID; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
The Francis hydro turbines are designed for the medium head power applications and in special circumstances, the high head Francis turbines are designed to convert the kinetic energy of the fluid to mechanical energy. The high head increases the potential of having high speed flow with high vibration levels. Hence, in high head Francis turbines design parameters should be optimized to get the maximum power output while avoiding abnormal phenomena such as excessive vibration, flow separation at the draft side, cavitation, and Karman vortex generation. Vane Pass Frequency (VPF) is one of the major issues that create series of harmful effects on the turbines and auxiliary parts because of superimposing of the vibration pulses and resonance of the adjacent parts. The VPF can resonate the auxiliary equipment, penstocks and turbines parts vibrate itself by forced vibration, which should be mitigated to protect the turbine. Hence, this research aims to study the flow induced vibration in high-head Francis turbines to establish the optimum parameters to mitigate the issues caused by vibrations. One of the power plants in Sri Lanka was used as a case-study for the research. At the final commissioning stage of this power station, a serious vibration and noise problem in the Francis turbine and steel penstock was detected. The dominant frequency of the vibration was identified as 180Hz and it was established that frequency generated from the turbine vanes. The study is continuing to analyse the remedial actions to minimize the vibration effects to the power plant equipment.
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Analysis of passenger perception on quality of service of railway transportation: coastal railway line, Sri Lanka
(IEEE, 2023-12-09) Thilakshan, T; Saranjan, P; Fernando, GVK; Bandara, JMSJ; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
The study focuses on assessing passenger perceptions of the service quality of the Sri Lankan Railways, focusing on the Coastal Railway Line in Sri Lanka. To determine areas for development and assess passenger satisfaction levels in terms of service quality, the study uses a questionnaire survey and interviews. The study considers important factors that affect passenger satisfaction, including air conditioning, seating comfort, and availability, the availability and usability of doors and windows, restroom amenities, and informational offerings. In order to increase overall passenger satisfaction, the study identifies the need to improve the level of punctuality, cleanliness, safety, comfort, and customer service. The Coastal Railway Line can become a more dependable, effective, and passenger-focused means of transportation by addressing these issues. Policymakers, transportation authorities, and other stakeholders can use the research findings to adopt the necessary improvements and actions that are in line with customer expectations. The ultimate objective is to support Sri Lanka's development of a viable and passenger-focused rail network, delivering a great travel experience for all rail customers. The railway system can foster a more welcoming environment for passengers and support the general expansion of the transportation industry with enhancements in these areas.
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An analytical approach for designing turbo expanders for organic rankine cycle
(IEEE, 2022-07) Ratnayake, RMSA; Bandara, RMAT; Sandaruwan, PHPL; Wijewardane, MA; Ranasinghe, RACP; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
ORCs (Organic Rankine Cycles) are becoming widely attractive for waste heat use since they facilitate power generation from low thermal content supplies. ORC may be optimized in various ways after determining the appropriate operating working fluid and design parameters. This article introduces a new design approach to produce a turbo expander demonstrated for a 1kW ORC utilizing R245fa as the working fluid. The obtained initial dimensions of the rotor were evaluated using performance criteria commonly used in turbo-machinery designing and the best results were selected after conducting several iterations. The inlet tip speed U 5 is considered as the primary design variable since it is restricted by mechanical stress considerations. The results obtained from the rotor analytical study are then utilized for stator, volute, and diffuser designs.
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An analytical design & optimization approach to enhance warehouse operations
(IEEE, 2021-07) Dissanayake, S; Rupasinghe, T; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
This paper presents an overview of integrating warehouse design and optimization modelling approach to enhance the supply chain performance. The approach is derived through a literature review as well as by considering the practitioners approach in the Sri Lankan context. The method is explained along with the framework to integrate the isolated solutions and derive the overall warehouse design solution, simulation, and optimization models. The main contribution of this paper is to guide the practitioners in consistently maintaining an optimum warehouse operation through warehouse design to enhance supply chain performance.
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Analyzing key determinants affecting electric vehicle adoption in Sri Lanka: a comprehensive evaluation
(IEEE, 2023-11-09) Saranjan, P; Thilakshan, T; Bandara, JMSJ; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
This study examines the factors influencing the adoption of electric vehicles (EVs) in Sri Lanka using a Multi- Attribute Utility Theory (MAUT) approach. The online questionnaire received responses from 210 participants, providing valuable insights into their preferences and expectations. The Likert scale was employed to assess the importance of various factors and attributes associated with EV adoption. MAUT was applied to analyze the collected data, taking into account multiple criteria and subjective user preferences. The analysis highlighted the significance of vehicle performance, financial factors, government policies, environmental concerns, product knowledge, social influence, and infrastructure availability in shaping EV adoption. Furthermore, the study also identified the importance of specific attributes within each factor and the preferences of the different respondent groups. These findings contribute to a deeper understanding of the factors driving EV adoption and guide policymakers and stakeholders in promoting sustainable transportation solutions in Sri Lanka.
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Analyzing the battery thermal behaviour under Sri Lankan driving and ambient conditions
(IEEE, 2023-12-09) Padmaperuma, C; Dissanayake, P; Gajanayake, S; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
On par with the technological advancements, the usage of electric vehicles (EVs) has been significantly prevalent in most parts of the world, even in the developing third world countries. During the study, it focusses on the battery electric vehicles (BEVs) and an analysis on the thermal behavior of the battery of a BEV is performed. A two-way analysis is conducted since both theoretical approach and the simulation-based approach are utilized. The thermal profile of the battery of a BEV is analyzed against the modelled localized driving pattern, i.e., Colombo Metropolitan Driving Cycle and when the analysis is performed, local ambient temperature conditions have been used. Functional relationships have been developed between the tractive power and the power generated from the battery and the thermal profile which is determined theoretically is compared against the simulation-based battery thermal profile which is generated using MATLAB Simscape development environment. Significant similarities are witnessed between the theoretical plots and the plots which are generated by the simulations whereas certain discrepancies have also been identified and critically analyzed.
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Analyzing the optimum contact angles of water droplets to mitigate the e-field stress on polymer insulator
(IEEE, 2022-07) Antony, AD; Arachchi, BATNKB; Gunasinghe, JB; Gunawardana, M; Samarasinghe, R; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The water droplets present in the insulator surfaces cause variation in the e-field along the insulator surface. Variation in the e-field can lead to flashover and accelerate the ageing of the insulator and ultimately will end up in the breakdown of the insulator. The contact angle of water droplets is also a factor that determines the e-field variation. In this study, the effect of the contact angle of water droplets is analyzed using a simulation approach for different cases considering both pure and contaminated outdoor polymer insulators. The results show that the optimum range of contact angles of water droplets can be concluded as 70 to 120 degrees for a pure insulator, while the optimum range for a polluted insulator can be given as 70 to 100 degrees.
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Applicability of eco-friendly solar adsorption refrigeration systems to reduce the energy consumption in industrial refrigeration applications
(IEEE, 2023-12-09) Punchihewa, KUC; Abeynayake, AADI; Weerasinghe, TS; Wijewardane, A; Amarasinghe, S; Jayasekara, JAGS; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Hot and humid countries in the tropics spend a significant amount of energy for their refrigeration and air conditioning (RAC) applications due to the year-round high temperatures and relative humidities in the region. The choice of an efficient RAC system will reduce the cost of energy as well as the emission of greenhouse gasses while controlling the required thermal condition for the given applications. Introducing and off-grid RAC system for a multi-day fishing boat beneficial as currently a fishing boat carries ice to fish ratio of 2:1 per one turn, to preserve the catch. The presence of onboard refrigeration system powered by renewable energy, will triple the fish harvest per turn due to the savings of the space occupied by ice. The conventional refrigeration systems such as the Vapor Compression Refrigeration systems consume electricity due to the compression process. A solar powered adsorption refrigeration systems can be a better alternative to a vapor compression system. The systems can be designed from a pair of Activated Carbon - Ammonia as adsorbent - adsorbate pair. Adsorption bed can be heated by the solar radiation instead of fossil fuels. This paper presents the numerical analysis of a solar-adsorption refrigeration system for fish preservation application.
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Application of hec-ras 2d model to simulate scour depth around bridge piers-a case study on Kelanisiri bridge, Sri Lanka
(IEEE, 2023-12-09) Thembiliyagoda, A; De Silva, K; Wijayaratna, N; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Scouring refers to the lowering of the level of river bed due to water erosion. Formation of vortices in the vicinity of bridges due to obstruction caused to river flow by piers and abutments is the core rationale behind this pursuit. Precise scour depth prediction allows for cost-effective proactive measures, preventing more disruptive actions required when addressing advanced stage scour related issues. Within the scope of this study, a two-dimensional numerical model is developed using the HEC-RAS software for the determination of scour depth around the bridge piers of Kelanisiri bridge. Change in bed elevation around the bridge pier provides the depth of scour hole formed due to a considered flood event. A scour depth of 3.8 m and 4.3 m were obtained around the two piers of Kelanisiri bridge. Results of the simulation were validated with observed data and model performance was analyzed using statistical parameters. As per the results, two-dimensional hydraulic model coupled with the sediment transport model produced a reliable estimation of the river bed level change and the scour depth around the bridge piers. Further validation of the model results can be accomplished based on a series of laboratory-scale experiments.
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Application of lstm and ann models for traffic time headway prediction in expressway tollgates
(IEEE, 2022-07) Phan, QTN; Mondal, M; Kazushi, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Traffic time headway is essential to support decision-making in safety management, capacity analysis, and service provision. Many studies on the time headway distribution on highways and urban roads serve two primary purposes. The studies that serve the latter purpose, service level, have not been given adequate attention. In fact, at manual toll stations, traffic congestion is still a severe problem. Predicting the time headway at toll stations becomes extremely meaningful when the service providers can allocate resources reasonably, minimizing waiting time in off-peak periods and utilizing resources during high-demand periods. This study applies two modern machine learning methods to predict the time headway at Niigata toll stations, Japan, namely Long Short-term Memory (LSTM), which only requires simple input of time series, and Artificial Neural Network (ANN), which requires some additional external features. The data set is the time headway of vehicles on expressways, along with the weather information and the vehicle’s average speed for five working days. There needs to be a trade-off between computation time, input data complexity, and model accuracy. Thus, tollgate operators could choose a suitable model based on their actual situation.
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Application of metaheuristic algorithms for generation system adequacy evaluation
(IEEE, 2023-12-09) Amarasinghe, PAGM; Abeygunawardane, SK; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
The evaluation of generation system adequacy has become a complex procedure due to the variability of renewable power generation. Renewable power models associated with Monte Carlo Simulation (MCS) require a considerable amount of processing power, especially when periodical variations of renewables are modeled. This paper analyses the application of different metaheuristic algorithms for evaluating the adequacy of renewable-rich power generation systems. The IEEE reliability test system is modified and used for conducting several case studies. The utilized metaheuristic algorithms are validated using sequential simulations and it is found that problem-specific Evolutionary Swarm Algorithm (ESA) provides more accurate estimations for generation system adequacy indices. In this study, the improvement of generation system adequacy is analyzed when integrating different renewable power proportions into the system. The intra-day reliability variation of the system is analyzed for different solar and wind penetration levels. The reliability improvement provided by renewable generators to the generation system adequacy is quantified by estimating the respective Effective Load Carrying Capabilities (ELCCs) of solar and wind generation. The ELCCs of 100 MW solar and 100 MW wind generation are found to be 26 MW and 43 MW, respectively.