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Journal Cover   Engineer : Journal of the Institution of Engineers, Sri Lanka
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  This is an Open Access Journal Open Access journal
   ISSN (Print) 1800-1122
   Published by Sri Lanka Journals Online Homepage  [46 journals]
  • Analysis on energy efficiency and optimality of LED and photovoltaic based
           street lighting system

    • Abstract: This study evaluates the optimality and energy efficiency of Light Emitting Diode (LED) and Photovoltaic based street lighting systems as a part of energy conservation. This evaluation is based on the detailed review carried out through a country wide street lamp survey.Since LEDs are becoming increasingly competitive due to their rapidly increasing efficiencies and decreasing cost, this research assessed the LED fixtures which have the capability of achieving 50% to 70% energy saving potential compared to the existing established technologies based street lamps available in the country. As a case study, illumination levels were examined at two neighboring traffic junctions in the Capital City, from Bambalapitiya junction to Kollupitiya junction. Two kinds of measurements were taken and average luminance levels were analysed for all measured points in the traffic lanes. It was found that same lighting performance could be achieved by replacing 250W HPS (High Pressure Sodium) by 150W HPS and further it was verified the same results while having 62% energy saving by replacing 250WHPS lamps with 111W LED through a simulation with Lighting RealityTM software. This change would easily meet the minimum recommended level of 7.5 Lux and average luminance of 0.5 cd/m2as per British Standards. Even though solar powered street lighting systems need high capital outlay, it will be one of the most appropriate energy solutions for a country like Sri Lanka. Incentive program development by the government may further encourage LED street lamp and solar powered system development adoptions. This study also recommends that any such incentive program should include performance standards that consider warranty, efficacy and other important criteria as the next steps. ENGINEER, Vol. 48, No.01, pp. 11-20, 2015 Published on 2015-09-30 00:00:00
  • From the Editor...Vol48(1)

    • Abstract: No abstract availableENGINEER, Vol. 48, No.01, pp. III, 2015 Published on 2015-09-30 00:00:00
  • HEC-HMS model for runoff simulation in a tropical catchment with
           intra-basin diversions – case study of the Deduru Oya river basin,
           Sri Lanka

    • Abstract: Hydrological modeling is a commonly used tool by water resource planners to simulate the hydrological response in a basin due to precipitation for the purpose of management of basin water. With the increasing demand for limited water resources in every basin, careful management of water resources becomes more important. The Deduru Oya river in Sri Lanka supplies water to number of new and ancient irrigation systems and the management of water resources in the Deduru Oya river basin, which has an area of 2620 km2, is important for optimum utilization of water for these irrigation systems. This paper describes a case study of continuous rainfall-runoff modeling in part of the Deduru Oya basin with intra-basin diversions and storage irrigation systems using the Hydrologic Engineering Center – Hydrologic Modeling System (HEC–HMS) version 3.0.1 to estimate runoff in the Deduru Oya river.Long term daily rainfall data at several rain gauging stations, evaporation, land use and soil data in the river basin, daily river runoff at a stream gauging station, intra-basin diversions from the river into a storage reservoir, irrigation releases from the reservoir and drainage flow returned to the river from irrigation systems were used to set up the HEC-HMS model. Five-layer soil moisture accounting loss method, Clark unit hydrograph transformation method, and recession base flow method of the HEC-HMS model were used. Temporally varying irrigation water uses, storages and losses in the basin were taken into account in the analysis. The results depict the capability of HEC–HMS to reproduce stream flows in the basin to a high accuracy with averaged computed Nash Sutcliffe efficiencies of 0.80. The study demonstrates potential HEC–HMS application in flow estimation from tropical catchments with intra-basin diversions and irrigation storages. The model developed is a tool for water management in the Deduru Oya river basin. ENGINEER, Vol. 48, No.01, pp. 1-9, 2015 Published on 2015-09-30 00:00:00
  • Coastal investigations for sustainable development of fisheries

    • Abstract: Plans have been formulated by the government to increase the fish production and the national targets indicate significant increases in marine fisheries production. The expansion of the marine fishing fleet and the development of appropriate fisheries infrastructure for the operation of such craft would play a vital role in achieving the future targets for fish production. A number of studies were thus conducted to assess the feasibility of developing sustainable fisheries infrastructure in various parts of the country. The attention in these investigations was mainly focused on related coastal engineering aspects in order to minimise the adverse impacts on the facility as well as the neighbouring coastline to ensure the sustainability and effectiveness of any proposed development. Attempts were made to assess, qualitatively, the exposure of the sites to the nearshore wave climate and the resulting coastal processes related to sediment (sand) transport in the vicinity. The forms of coastal constructions required were identified and the severity of potential impacts due to such developments was considered to assess the suitability of the sites for potential development. The details of selected investigations conducted in eastern, northern, south-western and southern regions are presented and the recommendations are elaborated. ENGINEER, Vol. 48, No.01, pp.71-81, 2015 Published on 2015-10-07 00:00:00
  • Projecting turbidity levels in future river flow: a mathematical modeling

    • Abstract: Climate and land use change impacts on river flow were evaluated in this study with emphasis placed on turbidity. Turbidity levels for the year 2020 were projected for Gin River, one of the prime sources of drinking water in Southern Sri Lanka. Future land use in the Gin catchment was predicted using a GIS based statistical regression approach. Regional Climate Modelling system generated the future rainfall for the SRES A2 and SRES A1B emission scenarios. Streamflow simulations were carried out using a distributed hydrologic model, and turbidity values were determined using rating curve based relationship developed between river discharge and TSS (Total Suspended Solid) concentration followed by Turbidity-TSS linear regression correlation.Increased turbidity levels are clearly evident under the SRES A2 scenario, following more pronounced increased stream flows. Projected 75th percentile monthly turbidity values in year 2020 are expected to increase during May to November compared to the baseline, and in certain months, about 100%increase is noted. 60% of the time, year 2020 turbidity levels have indicated exceedance of the water quality standards set for the potable water as well the inland waters of Sri Lanka, which would lead to exert extra challenge on future drinking water production in Southern region of Sri Lanka. ENGINEER, Vol. 48, No.01, pp. 61-70, 2015 Published on 2015-10-07 00:00:00
  • Monitoring of exhaust gas parameters of stationary combustion systems In
           view of environmental standards

    • Abstract: During the last few years, fossil fuel consumption for electricity generation and industrial process activities has gradually increased with the rapid development of energy and industrial sectors in Sri Lanka. When the fuel consumption increases, the relative quantities of emissions released to the environment too will increase. Such types of common emissions are toxic gases (Pb, Cl2), noxious gases (SOx, NOx), green house gases (CO2, O3), unburned gases (CO, CxHy), volatiles and respirable particles. Those emissions will harmfully affect, in different ways, the human health and the environment. The regulatory bodies have actively monitored the industrial emissions by implementing & amending old inactivated policies, regulations and standards. As a result of such implementations, under the “Section 32 of National Environmental Act No. 47 of 1980” as amended by Acts 56 of 1988 and 53 of 2000, the latest environmental standard for emission regulations for stationary combustion systems has emerged. In this regard, this paper aims to broadly discuss the experience gathered by the author in this area, in (view of) relation to' industrial impacts, instrumentations, pre facility requirement & resource availability and external interferences. Further the recommendations made in this paper for individual combustion systems, such as, thermal power plants, standby generators, industrial boilers & thermic fluid heaters, incinerators and cupola furnances, kilns etc. might be helpful to the regulatory bodies, industries, instruments & equipment suppliers and monitoring organizations in different ways when introducing (introduce) those emission standards to the industries. Finally, the outcomes of this study will help not only the local industries, but also Asian regional countries which have been operating similar combustion systems, to upgrade their systems to comply with particular environmental standards, because the proposed local standards have been prepared based on the other Asian and European regions’ environmental standards.ENGINEER, Vol. 48, No.01, pp. 51-60, 2015 Published on 2015-10-07 00:00:00
  • An approach to seismic analysis of (engineered) buildings in Sri Lanka

    • Abstract: Even though, Sri Lanka was believed to have no seismic threats, it is now realized that Sri Lanka can no longer be considered as a country safe from seismic threats following the recent events that occurred in and around the island. The present study is therefore aimed at providing guidance on suitable analysis procedure for buildings in Sri Lanka where the seismic consideration is explicitly warranted for a structure. The proposed guidelines in this study are based on Euro Code 8 (EN 1998-1: 2004): “Design of Structures for Earthquake Resistance”. Euro Code 8 was selected for this purpose as it allows national choices in defining seismic characteristics such as peak ground accelerations, response spectra, etc. in seismic design procedure. This study mainly focuses on these national choices and suitable values are proposed and discussed, depending on the available seismic data in Sri Lanka. Whenever there is a lack of data, suitable approaches are suggested comparing similar seismic codes such as IS 1893-1: 2002 and AS 1170.4: 2007. Finally, two case studies are carried out in order to illustrate how the developed guidelines can be used in the seismic design procedure of buildings particularly in Sri Lanka. ENGINEER, Vol. 48, No.01, pp. 39-48, 2015 Published on 2015-10-07 00:00:00
  • Use of dynamites, water-gels and emulsion explosives in Sri Lankan
           quarrying/mining practice

    • Abstract: In the Sri Lankan mining and quarrying industry, gelatine dynamite has been the widely used explosive for rock blasting purposes. In the recent past, it has been phased out and replaced by locally manufactured Water-gels(WG). So far, there had been only a very few tests conducted to assess the suitability and to evaluate the performance of this explosive with other available explosives. Complaints made by the users of Water-gels have been a cause of concern and prompted research to be conducted with the aim of evaluating the performance of Dynamites, Water-gels and Emulsion explosives with the measurement of major performance indicators in local mining and quarrying practice.In this research, performance comparison of WG, Dynamite and Emulsion explosives with regard to rock breakage in underground tunneling and in metal quarrying has been carried out. Comparison of fragmentation with the evaluation of particle size distribution in concrete block blasting using the three types of explosives has been one of the main tests. Gap sensitivity, density and the determination of velocity of detonation (VOD) has also been carried out. ENGINEER, Vol. 48, No.01, pp. 31-37, 2015 Published on 2015-10-07 00:00:00
  • Mitigation of delays attributable to the contractors in the construction
           industry of Sri Lanka - consultants’perspective

    • Abstract: This study focuses on determining important causes of construction delays attributable to contractors in large construction projects in Sri Lanka and the degree of severity of these causes. The causes of delay have been found based on the perceptions of the engineers working for three state affiliated establishments namely, Department of Buildings (BD), Road Development Authority (RDA) & National Water Supply and Drainage Board (NWSDB).The severity of each cause of delay is measured and represented through a severity index (SI). The causes of delay were determined and ranked in the descending order of severity. According to the findings, Poor project planning & scheduling (SI -82.54) is the most influencing factor causing delays in construction projects. In the descending order of severity, the other causes of delay are Low profit margin (SI -80.28), Inadequate cash flow management (SI -78.31), Handling of too many project sat a given time (SI -75.21), and Incompetence of the key staff (SI -74.93).Spearman rank correlation coefficient was used to determine the degree of agreement on the ranking of severity of causes of delay among the organisations. The highest degree of agreement is between BD & NWSDB (0.77). There exists an intermediate degree of agreement between RDA & NWSDB (0.73) and the lowest is between RDA & BD (0.70).The study finally makes 10 recommendations to mitigate construction delays. ENGINEER, Vol. 48, No.01, pp. 21-30, 2015 Published on 2015-10-07 00:00:00
  • From the editor Vol.48(3)

    • Abstract: ENGINEER, Vol. 48, No.03, pp. iii 2015 Published on 2015-09-09 00:00:00
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Heriot-Watt University
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