Browsing by Author "Perera, M"

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Open Access
Aeroacoustic Noise Produced from Novel Wind Turbine Rotor Design for Small-scale Applications in Sri Lanka
(SLIIT, 2022-02-11) Perera, M; Bandara, U. H
Growing concerns regarding non-renewable energy sources have driven academic and industrial scholars as well as global superpowers to seek sustainable, greener power generation alternatives. One such prominent renewable substitute is wind power which was initially utilized in harnessing electricity towards the late nineteenth century though archaeological evidence has proved that wind power had been employed for various purposes since predynastic Egypt. Extensive research and development has enabled the efficient operation of multi megawatt wind farms at present though inherent drawbacks still persist, of which aerodynamic noise, also referred to as aeroacoustic noise, is of major concern. This paper details the simulative investigation of the aeroacoustic sound levels produced by an optimized novel wind turbine design intended for the use in small scale applications with medium wind speed conditions in Sri Lanka, using ANSYS Fluent. A transient analysis using the Shear Stress Transport turbulence model was used to obtain the converged pressure fluctuations which subsequently revealed the sound pressure levels via Fast Fourier Transforms at six predetermined locations of interest. The results revealed the presence of acoustic vibrations within the Infrasonic and Low Frequency Noise range with sound pressure levels exceeding one hundred decibels, particularly up to a frequency of twenty five Hertz. Prolonged exposure to elevated levels of low frequency noise has been identified to cause severe discomfort to humans though further conclusive research is required. Finer mesh controls which incorporate minute boundary layer variations during motion and precisely encapsulate the turbine geometry could further improve the accuracy of the results, however this would require adequate computational capacity. The results of this research primarily serve as a basis for identifying possible improvements for the novel rotor design in addition to providing a comparative study for future research, both simulative and empirical, on the aerodynamic noise emissions associated with wind turbines.
Embargo
Analyzing the Location Feasibility for Retail Businesses using Market Location Factors
(IEEE, 2018-12-21) Marasinghe, L; Rupasinghe, M; Kumarasinghe, B; Perera, M; Thelijjagoda, S
The retail industry is a fast growing and a highly revenue generating industry. The location of a retail outlet is the most influencing factor for the success of the business. Therefore selecting a location for a retail store or an outlet is a challenging process. The purpose of this study is to define a method and develop a system to analyze the feasibility of a selected location for a retail store. The factors used in this method are location and market factors of a selected area. In order to define and test the method, we selected three different areas and five different retail store types. To retrieve location data, we used Google Maps web service. Consumer surveys were conducted in selected areas to get information about consumers' shopping patterns and selections. From the web service, we were able to identify transport modes, locations of competing stores and shopping areas. The findings of this study and the method described is useful in deciding the feasibility of any given location for a retail outlet. Also the specified method and model can be modified and extended to analyze different kinds of business locations.
Open Access
Design and Dynamic Modelling of Knee Exoskeleton for Disabled People through ADAMS-Simulink Co-simulation
(SLIIT, Faculty of Engineering, 2022-09-22) Ranaweera, J. P; Perera, M
This paper is written to outline the progress and findings of an undergraduate research project aimed at the designing and modelling of an exoskeleton design of the knee joint for rehabilitation and gait support. It focuses on the rehabilitation potential of the proposed exoskeleton design on patients with Hemiplegia and Monoplegia conditions with the objective of seeking a feasible, simple means of joint actuation to reduce the complexity of the design. Exoskeleton designs are able to provide rehabilitation and improve the overall quality of life of disabled people globally. However, a common issue found almost everywhere is the costly nature of the exoskeletons that are available in the market now as they are exclusive devices, which makes them inaccessible and impractical to the general public, especially in developing countries. Initially, the paper focuses on the review of relevant literature and previous research and evaluating the designs that have been developed as of now. A thorough analysis of the work done by previous researchers and companies was conducted to gather data on the underlying engineering principles and techniques used for the exoskeleton development as well as any limitations or restrictions to the process. Conceptual designing of the possible solutions was developed using the understanding and knowledge gathered during the literature review. The selection of the best solution was based on the analysis of the pros and cons of all the solutions. The chosen design, utilising a 4-bar mechanism, was then modelled using SolidWorks software to provide a clear visualisation of the system. The kinematic and dynamic analysis of the mechanism was evaluated to analyse the possibility of using the proposed exoskeleton design by replicating the model in ADAMS multibody software. The dynamic analysis was conducted by using the co-simulation platform between ADAMS and Simulink to enable the addition and control of feedback loops within the system. The results of the analysis show that the design can achieve the required motions of the human gait cycle, especially during the swing phase of the gait cycle. The analysis of the actuation torques and reaction forces on the human body showed that an acceptable torque range was possible during the swing phase of the gait cycle.
Open Access
Development of an underwater robotic arm using multibody dynamics approach
(2022-02-05) Fernando, S; Perera, M
Underwater robotic arms are important devices that enables workers to carry out tasks remotely from a safe distance reducing or eliminating the risks that are involved with the task. The primary objective of the robotic manipulator is to perform maintenance and cleaning activities of the hull of a ship. However, the control of these devices underwater is quite complicated due to the numerous factors that make these systems unstable and non-linear. The aim of this study is to develop a multibody dynamic robotic manipulator model, integrated with a control strategy to optimize and obtain stable kinematics solutions. The hydrodynamic forces are integrated to the manipulator model considering buoyancy forces and surface drag forces. A basic algorithm is used to generate the joint angles using 7 geometrical parameters. The control of the manipulator was done to simply follow any path that represents the given coordinates. The P, I and D parameters are tuned individually to optimize the kinematic solution of the manipulator. 3-DOF articulated manipulator is the commonly used manipulator configuration. However, a 6-DOF manipulator configuration was selected in this study to allow for change in orientation using wrist motions.
Open Access
Evaluation of Antibacterial Activity of Rhinacanthus Species in Sri Lanka
(Faculty of Humanities and Sciences, SLIIT, 2023-11-01) Somaratne, Y; Perera, M; Karunagoda, R
Rhinacanthus nasutus (L.) Kurz is a valuable medicinal plant belonging to the family Acanthaceae that has many applications in the Ayurvedic system of medicine in Sri Lanka. Rhinacanthus polonnaruwensis Cramer is a more recently discovered species endemic to Sri Lanka, but its medicinal properties have not been recorded so far. The objective of the present study was to screen the antibacterial activity of leaf extracts of R. nasutus and R. polonnaruwensis against clinically isolated Gram-negative and Gram-positive bacteria. The study was carried out on six bacterial species, Escherichia coli, Staphylococcus aureus, S. saprophyticus, Pseudomonas aeruginosa, Salmonella typhi and Shigella flexi. Polar extracts of R. nasutus and R. polonnaruwensis were obtained by grinding the leaves with sterilized water and boiling the leaves in distilled water to obtain a decoction. A decoction of the concentration of 0.2 ml/ml of R. nasutus inhibited growth of all standard Gram-positive bacteria; Staphylococcus aureus and MRSA, whereas 0.2 ml/ml of decoction of R. polonnaruwensis inhibited growth of Staphylococcus aureus. Clinically isolated Staphylococcus saprophyticus was inhibited by both decoctions of Rhinacanthus species. None of the tested concentrations of the two Rhinacanthus species inhibited the growth of any Gram-negative bacteria; Pseudomonas aeruginosa, Escherichia coli, and Shigella flexi. In this study, we demonstrated that the leaf extracts of both R. nasutus and R. polonnaruwensis were effective at inhibiting Gram-positive bacteria. However, the decoction of R. nasutus was found to be more effective against the tested Grampositive bacteria than R. polonnaruwensis.
Embargo
IDairy: Intelligence and Secure E-Commerce Platform for Dairy Production and Distribution Using Block Chain and Machine Learning
(IEEE, 2022-07-18) Liyanage, I; Madhuwantha, N; Perera, M; Ruhunage, S; Mahaadikara, M. D. J. T. H; Rupasinghe, L
The dairy industry plays an essential role in the Sri Lanka economy. The purpose of this study is to reduce the cost of import dairy products and increase the profit of the dairy industry. IDairy: Intelligence and secure e-commerce platform for dairy production and distribution using blockchain and machine learning has been suggested as a mobile application. As a first step, this research suggested four factors. Develop a business intelligence dashboard using predictive analysis and provide business solutions to dairy companies described the revenue for the coming month using machine learning and the earning data charts for years to come to display in the dashboard. Design IOT device to maintain the temperature of fresh milk cargo while transporting to productions and design smart contract to maintain the optimum temperature for the fresh milk harvest. Develop a system to identify the cows’ diseases using image processing the primary objective was identified cows’ Foot and Mouth diseases and provide notifications to milk farms about existing illnesses. Cows’ disease directly affects dairy productions. Develop a mobile application for farmers to store animal data, do profit calculation, including giving business solutions through the application with location tracking service. With this IDairy application, both farmers and production companies will be able to get an idea about their future profit and will be suggesting the business solutions.
Open Access
Power Management Strategy of a Parallel Hybrid Three-Wheeler for Fuel and Emission Reduction
(Multidisciplinary Digital Publishing Institute, 2021-01) Maddumage, W; Perera, M; Attalage, R. A; Kelly, P
Millions of three-wheelers in large cities of Asia and Africa contribute to the already increasing urban air pollutants. An emerging method to reduce adverse effects of the growing three-wheeler fleet is hybrid-electric technology. The overall efficiency of a hybrid electric vehicle heavily depends on the power management strategy used in controlling the main powertrain components of the vehicle. Recent studies highlight the need for a comprehensive report on developing an easy-to-implement and efficient control strategy for hybrid electric three-wheelers. Thus, in the present study, a design methodology for a rule-based supervisory controller of a pre-transmission parallel hybrid three-wheeler based on an optimal control strategy (i.e., dynamic programming) is proposed. The optimal control problem for minimizing fuel, emissions (i.e., HC, CO and NOx) and gear shift frequency are solved using dynamic programming (DP). Numerical issues of DP are analyzed and trade-offs between optimizing objectives are presented. Since DP strategy cannot be implemented as a real-time controller, useful strategies are extracted to develop the proposed rule-based strategy. The developed rule-based strategy show performance within 10% of the DP results on WLTC and UDC-NEDC drive cycles and has the clear advantage of being near-optimal, easy-to-implement and computationally less demanding.
Open Access
Power Management Strategy of a Parallel Hybrid Three-Wheeler for Fuel and Emission Reduction
(Multidisciplinary Digital Publishing Institute, 2021-01) Maddumage, W; Perera, M; Attalage, R; Kelly, P
Millions of three-wheelers in large cities of Asia and Africa contribute to the already increasing urban air pollutants. An emerging method to reduce adverse effects of the growing threewheeler fleet is hybrid-electric technology. The overall efficiency of a hybrid electric vehicle heavily depends on the power management strategy used in controlling the main powertrain components of the vehicle. Recent studies highlight the need for a comprehensive report on developing an easyto-implement and efficient control strategy for hybrid electric three-wheelers. Thus, in the present study, a design methodology for a rule-based supervisory controller of a pre-transmission parallel hybrid three-wheeler based on an optimal control strategy (i.e., dynamic programming) is proposed. The optimal control problem for minimizing fuel, emissions (i.e., HC, CO and NOx) and gear shift frequency are solved using dynamic programming (DP). Numerical issues of DP are analyzed and trade-offs between optimizing objectives are presented. Since DP strategy cannot be implemented as a real-time controller, useful strategies are extracted to develop the proposed rule-based strategy. The developed rule-based strategy show performance within 10% of the DP results on WLTC and UDC-NEDC drive cycles and has the clear advantage of being near-optimal, easy-to-implement and computationally less demanding.
Embargo
Power Profiling: Assessment of Household Energy Footprints
(IEEE, 2021-03-06) Wijesinghe, V; Perera, M; Peiris, C; Vidyaratne, P; Nawinna, D; Wijekoon, J
Reduced energy footprint is considered an indicator of efficiency around the world. Having insights into electricity consumption behavior of individuals or families across the day is very useful in efficient management of electricity. In this paper, we present s study that focused on identifying patterns in the monthly electricity consumption profiles of a single household with the K-means clustering algorithm. The data required for this study was collected through a survey in the Sri Lankan context. The survey mainly captured the factors affecting electricity consumption. After proving the demand of electricity is dependable on the data that has been collected, they will be keyed into data models/ profiles that will be built using clustering algorithms. A load profile will be designed using K-means to identify usage patterns of a household on a monthly basis. The parameters that affect the electricity consumption were tested and trained using the SVM algorithm. The outcomes of this study include; identifying the factors contributing to the electricity consumption, identifying electricity consumption patterns, identifying the energy footprint of individuals or families and predicting the future electricity requirements. The results of this study provide many advantages for both consumers and suppliers in efficient management of electricity. It also provides significant impacts in both micro and macro levels through enabling efficient decision-making regarding management of electricity.
Embargo
Power Profiling: Assessment of Household Energy Footprints
(IEEE, 2021-03-06) Wijesinghe, V; Perera, M; Peiris, C; Vidyaratne, P; Nawinna, D. P; Wijekoon, J
Reduced energy footprint is considered an indicator of efficiency around the world. Having insights into electricity consumption behavior of individuals or families across the day is very useful in efficient management of electricity. In this paper, we present s study that focused on identifying patterns in the monthly electricity consumption profiles of a single household with the K-means clustering algorithm. The data required for this study was collected through a survey in the Sri Lankan context. The survey mainly captured the factors affecting electricity consumption. After proving the demand of electricity is dependable on the data that has been collected, they will be keyed into data models/ profiles that will be built using clustering algorithms. A load profile will be designed using K-means to identify usage patterns of a household on a monthly basis. The parameters that affect the electricity consumption were tested and trained using the SVM algorithm. The outcomes of this study include; identifying the factors contributing to the electricity consumption, identifying electricity consumption patterns, identifying the energy footprint of individuals or families and predicting the future electricity requirements. The results of this study provide many advantages for both consumers and suppliers in efficient management of electricity. It also provides significant impacts in both micro and macro levels through enabling efficient decision-making regarding management of electricity.
Open Access
Review on vibration quality improvement of a passenger seat
(researchgate.net, 2019-03) Perera, M; Rikaz, M; Abeysinghe, A
Seats are one of the most significant components of vehicles. Customer’s expectations for the comfort in vehicle seats rise continuously. Designing of automobile seats has always been a challenge for engineers as design parameters for automobile seats are complex. When it comes to the design of automobile seats, three design objectives, namely comfort, safety and health need to be fulfilled simultaneously. Vibration analysis plays a major role in engineering including the area of design for automobile comfort. Human structure, as a mechanical system, is immensely complex and the mechanical properties of human body readily undergo change. In addition, the vibration can initiate the development of pressure ulcer and other long-term diseases. Comfort measurement is challenging because of such factors as user subjectivity, seat geometry, occupant anthropometry and amount of time spent sitting. The purpose of this study is to identify the most significant parameters that make vibration in the vehicle seat which reduce passenger comfort and to identify the design parameters that can impact on appropriate seat design. Suspension systems, seat cushion and sitting postures are some of the vital parameters that have huge impacts on comfort analysis. This review could help in design of seat cushions with appropriate material properties and in analysing the comfort levels of human body to reduce the vibration transmissibility at the critical frequency bands
Embargo
Translation and Adaptation of a Dysarthria Assessment Tool to Be Used in the Sri Lankan Clinical Context
(Faculty of Humanities and Sciences,SLIIT, 2021-09-25) Perera, M; Rathnayaka, S
Dysarthria is one of the common communication disorders that arises due to neuromuscular damage. To address this long-felt need of a formal Dysarthria tool to be implemented in the Sri Lankan clinical context, the Newcastle Dysarthria Assessment Tool (N-DAT) was adapted and validated using a normative sample during this research study. The adaptation and validation were done using three phases: (I) Identification of the most appropriate tool to adapt to SL context, (II) Translation and adaptation of the assessment tool, and (III) Identification of the face, content, and concurrent validity of the tool. At the end of the phase II, the original N-DAT assessment tool was translated and adapted to Sinhala language using WHO guidelines and Delphi methodology. The content was satisfactorily adapted and translated with the same conceptual meaning, semantics, idiomatic, score equivalences with one additional section related to the International Classification of Functioning model. The face validity and contented validity were confirmed with the Delphi group’s input. The normative sample exhibited a predicted negative correlation between age and speech- articulation, respiration, phonation, voice, pitch, and Diadochokinetic rates. The concurrent validity of the SLN-DAT was compared with another informal Dysarthria assessment that is used at National Hospital, Sri Lanka, and found to have high ICC for all subsystems. Each subsystem had higher Intra Class Correlation value ranging between r = 1.0 – 0.7 (p<0.01). However, this validation was done only among the normative sample where the SLN-DAT could be recommended to Sri Lanka after it was validated among the dysarthria population.