Browsing by Author "De Silva, K"

Now showing 1 - 10 of 10

item: Conference-Full-text
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.
item: Conference-Abstract
Assessment of exposure of Sri Lanka to tsunami hazards
(2019) De Silva, K; Ratnasuriya, H; Wijeratne, N
Nearly two third of the coastal zone of Sri Lanka suffered severe damages due to the tsunami caused by the undersea earthquake in the Sunda trench on 26 December 2004. The vast destruction was mainly due to the lack of awareness and preparedness in the country on tsunami hazards. The tsunami in 2004 and the subsequent tsunami alerts have highlighted the exposure of the country for such hazards. This study was focused on assessing the exposure of Sri Lanka to such potential tsunami events from Sunda trench using numerical simulations and to develop a database including information such as magnitude and location of earthquakes, tsunami travel times, deep sea and near shore wave heights and the extents of inundation which can be utilized for an early warning and evacuation system.
item: Conference-Full-text
Blockchain-based software subscription and licenses management system
(Information Technology Research Unit, Faculty of Information Technology, University of Moratuwa., 2023-12-07) De Alwis, H; Wijayasiri, A; De Silva, S; De Silva, K; Piyatilake, ITS; Thalagala, PD; Ganegoda, GU; Thanuja, ALARR; Dharmarathna, P
Current software licensing models exhibit shortcomings in transparency, security, and adaptability. Addressing these challenges, this study presents a novel blockchain-based licensing system using the Ethereum platform. By employing smart contracts and the ERC721 and ERC20 token standards, the system ensures automated, transparent, and secure license agreement enforcement and facilitates license token operations. Influenced by the rise of subscription licenses and the implications of the UsedSoft court decision, the research designs a blockchain-driven subscription license model, analyses the UsedSoft case’s impact on license transfers, and formulates specialized smart contracts for varied licensing models. The approach signifies a marked advancement in contemporary software licensing practices.
item: Conference-Full-text
Comparison of experimental results with empirical relationships for energy losses in pipe flow
(IEEE, 2021-07) Yogaraja, L; Liyanagamage, N; De Silva, K; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Estimation of energy losses in pipe flow is a prerequisite in designing pipe networks to verify the energy requirement in transferring fluid between two locations. There are two types of such energy losses namely: major losses which is caused by friction at the interface of pipe and the flow and minor losses which is caused due to local conditions such as sudden contractions, sudden expansions, and bends of the pipeline. In this paper, major and minor losses in pipe flow, calculated from empirical equations are compared with the experimental results using PVC pipes which is a popular commercial pipe category. For comparison on minor losses; Bend, Gradual contraction, Elbow bend, Gradual expansion, and 45 degrees bend which are widely used in distribution networks were used and coefficient of minor losses was used as a comparative factor. For comparison on major losses; PVC pipes with five different diameters were used and head loss vs Reynolds number variation was considered in the comparison. According to the results, the Blasius (1913) equation was found to be more accurate for actual flow, while using the Darcy-Weisbach equation found to be more predictive of the major head losses of water flow in PVC pipes.
item: Conference-Full-text
Design and experimental characterization of a soft bending actuator for morphing aerofoils
(IEEE, 2023-12-09) De Silva, K; Maduranga, S; Chamika, V; De Silva, L; Kulasekera, AL; Samaraweera, N; Jayaweera, ND; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
This paper presents the design, simulation, and experimental validation of a vacuum-driven, soft-bending actuator for morphing wing development for small fixed-wing unmanned aerial vehicles (UAVs). The actuator uses an origami-inspired folding mechanism as its control skeleton. A flexible 3D printed structure employing the NACA 2415 aerofoil was used for the development of the morphing aerofoil, driven by the proposed soft actuator. An experimental evaluation of the bending angle and blocking force characteristics of the proposed actuator was conducted. The actuator has achieved a maximum bending angle of 18.75°, while the maximum blocked force at the tip measured 4.8 N at 40 kPa (abs) pressure. Furthermore, aerodynamic simulations revealed that increasing the length of the morphing section with respect to the aerofoil length (Morphing Section Ratio: MSR) resulted in elevated Cl and Cd, while the maximum Cl/Cd values are achieved near the trailing edge morphing. The findings of this study suggest the suitability of soft actuators in the development of flexible morphing wing structures for smallscale UAVs.
item: Conference-Abstract
Gender equity in disaster early warning systems
De Silva, K; Amaratunga, D; Haigh, RP
Capacities of societies, communities and individuals or a social-ecological system to deal with adverse consequences and the impacts of hazard events define the resilience. New and innovative Emergency Communications, Warning Systems (ECWS) technologies and solutions improve resilience of the nations. Research shows that different types of systems (e.g. decision support, resource management, early warning, communications, and inter-agency) are highly valued in emergency and disaster events reducing live losses. As many individuals have online access today and young women have increased their online communication and young men tend to explore technology resources, the potential of using user friendly third revolution digital technology such as semantic features and devices (e.g. SMART phones) have the potential to improve the access to early warning/risk information supporting community decision making saving lives. These personal and social relations that reflect gender dimensions can certainly be examined improving resilience making communities more prepared for disasters with proactive decision making for early warning. Fostering awareness about gender equity which is the recognition of women and men as active participants in development can tailor made within the context of resilience and more specifically within early warning systems saving lives of the people at immediate risk including the dependence of mother’s care (children and older people). In this context, this paper attempts to synthesis literature on the topic of gender equity within disaster early warning systems.
item: Conference-Full-text
Investigations on wave energy characteristics in South-Western coastline of Sri Lanka
(IEEE, 2022-07) Theivendren, T; De Silva, K; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The aim of the study is to investigate the wave power potential around the south-western coast of Sri Lanka and its spatio-temporal and directional distributions based on 5 years (1999 to 2003) of simulated wave data. The analysis results show that the annual mean wave power in the region is exceeding 10 kW/m while the available monthly mean wave power values are higher than 5 kW/m throughout the year. Eight study points were selected along the nearshore coastline for a detailed assessment. The calculated annual and monthly mean wave power values at the selected points showed that the south-west coast has a higher potential than the west coast except near Matara. The temporal and directional variations were also assessed in selected points using statistical indices and wave power roses, and those revealed that the region has moderately stable wave power with narrow directionality. Moreover, the possible annual electric power outputs from three wave energy converter devices (WECs) were estimated at all the study points using wave scatter diagrams and publicly available power matrices, and the results reveal that the nearshore area from Galle to Weligama is most suitable for wave energy harvesting.
item: Thesis-Abstract
Latex blends of natural rubber and nitrile rubber with chloroprene rubber: improvement in compatibility and properties
De Silva, WNL; De Silva, K; Karunanayake, L
Latex is a colloidal dispersion of a polymer substance in an aqueous medium. Latex blends of natural rubber (NR) and several synthetic rubber latices (e.g. chloroprene rubber (CR), nitrile rubber (NBR), styrene butadiene rubber (SBR) etc. ) have been used extensively for manufacturing various rubber products including foam rubber and gloves. In NRlNBR latex blend interfacial tension between NR and NBR is very high due to the differences in polarities of the two latices. Therefore the compatibility and hence the miscibility of NRlNBR latex blend is low. In this study an attempt was made to use CR latex as a compatibilizing agent in NRlNBR latex blends. Using FT-IR spectra it was found that addition of CR latex to NRlNBR latex blend has .caused a chemical shift. Hence the properties of NRlNBR latex blend and NRlCRlNBR latex blend were studied. It was found that the tensile strength ofNRlCRlNBR latex blend is greater than NRlNBR latex blend. Further the solubility parameter of CR latex was found to be between NR and NBR. Hence it was found that CR latex can be used to improve the strength and miscibility ofNRlNBR latex blends. The effect of addition of CR latex on other properties of NRlNBR latex blend (water extractable protein content and oil resistance) were studied and it was found that there was no adverse effect on those properties with the addition of CR latex to NRlNBR latex blend. Therefore it can be concluded that CR latex can be used as a suitable compatibilizing agent ~nNRlNBR latex blend.
item: Thesis-Abstract
Multi - storey housing for urban poor : socio-economic and functional viabilities in Colombo
De Silva, K; Munasinghe, H
Architecture is for people have become a well known clinch which is being used without a precise comprehension of its deeper assets. Thus intern, it has created a discomfort in the ultimate user especially in the provision of housing of housing for the poor community dweller. Similarly, in a rigid grid iron pattern with, respectively stacked dwellings do not incorporate with the socio cultural context of the urban low income dwellers. At all the ultimate result is that their return to the original dwelling which creates shanty Settlements within urban premises. Thus more concern has to be given to the socio-cultural context of urban low income dwellers 1n order to examine the extent of its contribution for their dwelling designs. Housing settlement is a basic need for human existence. The present issue of housing has been comprehended as a provision of 'Homes' 'Housing'; as the developed shelter; a greater need of home making. This dissertation focuses on Multi-Storey apartments in Sri Lanka and provides an appropriate background for the study of its viability to house the urban poor in the city of Colombo. An in depth knowledge on this subject area is essential for the architects, as the multi storey apartments have become one of the universally accepted built form in the urban living environment. In the Sri Lankan context also it has become an efficient mean of fulfilling the requirements of housing in the urban sector. This dissertation intends to find out the viability of multi-storey apartments within the social, functional, and economic parameters prevailing in the city of Colombo. The study starts with review out the previous housing strategies, their advantages and disadvantages. Then looking at existing examples, by literature reviews and from participatory observation assesses the suitability of multi-storey living for urban poor. One of the major findings of the study is the absence of knowledge and proper education among urban poor category to introduce this type of a new concept. It was found that the people, who value our cultural features and the society as a whole, are not prepared to accept this type of buildings that had been successful in foreign countries. It was clearly understood that adherence to the essence of Sri Lankan architecture and understanding of urban social characteristics playa major role in popularizing multi-storey apartments among the urban poor.
item: Conference-Full-text
Third Revolution Digital Technology in Disaster Early Warning
(2016-01-05) De Silva, K; Amaratunga, D; Haigh, R
Networking societies with electronic based technologies can change social morphology, where key social structures and activities are organized around electronically processed information networks. The application of information and communications technologies (ICT) has been shown to have a positive impact across the emergency or disaster lifecycle. For example, utility of mobile, internet and social network technology, commercial and amateur radio networks, television and video networks and open access technologies for processing data and distributing information can be highlighted. Early warning is the key function during an emergency. Early warning system is an interrelated set of hazard warning, risk assessment, communication and preparedness activities that enable individuals, communities, businesses and others to take timely action to reduce their risks. Third revolution digital technology with semantic features such as standard protocols can facilitate standard data exchange therefore proactive decision making. As a result, people belong to any given hierarchy can access the information simultaneously and make decisions on their own challenging the traditional power relations. Within this context, this paper attempts to explore the use of third revolution digital technology for improving early warning.