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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  [48 journals]
  • Identification of the Polyethylene Grade Most Suitable for Natural
           Rubber-Polyethylene Blends used for Roofing Applications

    • Abstract: In Sri Lanka, roofing materials are manufactured with clay, metal, plastic, wood and asbestos, and each of these has its own inherent drawbacks. Asbestos due to the economic advantages it offers, is now the most widely used roofing material in the country. However, it has scientifically proven health risks. The Government of Sri Lanka has initiated action to ban the use of asbestos as a roofing material. The focus of this study is on the development of a roofing material formed of rubberthermoplastic blends containing Natural Rubber (NR) and Polyethylene (PE). Polyethylene is being currently used as a roofing material, but since it is lightweight it needs to be anchored tightly to the roof structure. Rubber being an energy absorbing material, can be incorporated into thermoplastics to make the latter more tough. Polymer blending is a current trend which is being used to develop technically advanced new materials from commonly available polymers. Polymer blends has an excellent combination of physicochemical properties of each of their parent materials. Sri Lanka exports natural rubber and thus there is a good opportunity to make value-additions to raw rubber exports. Similarly, the development of a new material will address the current problems associated with the use of asbestos as a roofing material. This study shows the most suitable grade of PE from among its most common grades such as High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE) and Linear Low Density Polyethylene (LLDPE), for blending with natural rubber The best blended composition that will have standard properties of a roofing material such as tensile strength, tear strength, hardness, water absorption level, thermal conductivity etc., is then identified. Published on 2016-11-22 00:00:00
       
  • A Comparison of Methods of Estimating Missing Daily Rainfall Data

    • Abstract: The availability of a long and complete rainfall record is very important for carrying out a hydrological study successfully. However in general, the data series in these records may contain gaps for various reasons. The objective of this study is to analyse the different methods available for filling gaps in rainfall data records and propose a method suitable for a river basin situated in a mountainous area in Sri Lanka. Towards this end, daily rainfall data from ten gauging stations in the upper catchment area of BaduluOya were collected. Seven different techniques were studied to ascertain their suitability. The methods studied were the Arithmetic Mean method, Normal Ratio method, Inverse Distance Weighting method, Linear Regression method, Weighted Linear Regression method, Multiple Linear Regression method and the Probabilistic method. The data generated for the target stations were compared with actual observations made, based on error statistics, Error Standard Deviation (STD),Root Mean Square Error (RMSE) and Correlation Coefficient (CC). The results of the study showed that for target stations that have only one neighbouring station with a high correlation coefficient, the Probabilistic method and the Linear Regression method give good predictions. For stations that have relatively low correlation coefficients with the neighbouring stations, the Inverse Distance Squared method and the Normal Ratio method outperformed the others. To obtain accurate results from the Multiple Linear Regression method and the Weighted Linear Regression method, it is necessary to have a set of neighbouring stations that have fairly high correlation coefficients with the target station. Published on 2016-11-22 00:00:00
       
  • Review of Roundabout Design Standards and the Development of a Roundabout
           Design Guideline for Sri Lanka

    • Abstract: In Sri Lanka, the geometry of roundabouts has a considerable influence on their operation. The increase in road traffic and the large number of long vehicles that ply on the roads have contributed to the malfunctioning of some of these roundabouts. The objectives of this study were to review the roundabout design guidelines, identify issues in the existing roundabouts and prepare a roundabout design guideline appropriate for Sri Lanka. Twenty four roundabouts located in some of the major cities were selected for the study. The design parameters of the geometries of the selected roundabouts were compared with those recommended in five major design guidelines. Data on the main geometric parameters of each roundabout were collected through field measurements and calibrated satellite images. The dimensions and the design parameters of these roundabouts were compared with those stated in a few international roundabout guidelines. A swept path analysis was carried out on selected roundabout layouts for single unit trucks to determine the adequacy of their entry widths, circulation widths, exit widths and operational speeds. The entry radiiwere higher than those recommended in the international standards. The design parameters of the existing roundabouts that required improvements were identified and suitable values for the selected design parameters have been proposed. Most of the roundabouts meet the minimum requirements specified in the international guidelines for the centre island diameter (100%), circulation width (92%), and exit radius (92%). Published on 2016-11-22 00:00:00
       
  • From the Editor Vol.49 (4)

    • Abstract: No abstract available Published on 2016-11-22 00:00:00
       
  • Path Ahead for Public Sector Engineers

    • Abstract: Sri Lanka is blessed with high calibre, technically competent engineers. However, the lack of proper administrative and regulatory systems in the country is cited as the main reason for the lacklustre performance of its public sector engineers. Engineers have to think differently, act more proactively and try out new processes and procedures to ensure that the organisations where they work are service centric and socially responsive. Public sector engineers have to be aware of their own limitations and should seek external guidance whenever necessary. Local engineers can make use of international concepts, methodologies, guidelines, codes of practice and tools towards this end. Strategic planning processes in the public sector organisations need radical changes. Engineers should apply the "systems view concept‟ holistically to assess the effectiveness of the management structure of their organisations. The organisational culture needs to be enriched with consultative decision making processes and teamwork. The Institution of Engineers, Sri Lanka (IESL) has to act as a facilitator in this process. The ultimate aim should be to embrace business excellence elements to be an integral part of each organisation concerned. Published on 2016-11-22 00:00:00
       
  • Assessment of the Impacts of Electricity Subsidies in Sri Lanka

    • Abstract: The government of Sri Lanka has been providing over decades, subsidies on electricity to uplift the living conditions of Sri Lankans. This research project scrutinizes whether the objectives of providing electricity subsidies have been fulfilled. Furthermore, both positive and negative impacts of the electricity subsidy are descriptively discussed. Appropriate remedial actions are proposed to lessen the effects of indirect negative impacts that are identified. Through the analysis, it was found that some of the primary objectives of the electricity subsidy have not been achieved. One of the most subtle negative impacts of the electricity subsidy is the encouragement it provides to subsidized consumers to use energy inefficient equipment. A case study was conducted in Ratnapura district to investigate the energy inefficient equipment usage and to quantify the resulting electricity wastage. The findings of the study were used to estimate the amount of electricity wasted in the entire country through the use of inefficient equipment. Furthermore, it was found that the existing tariff structure encourages energy inefficient equipment usage and that it therefore acts in contradiction to the fundamentals. The replacement of incandescent lamps by energy efficient equipment is analyzed as a means of saving electricity and meeting the demand during peak times in the night, and resulting savings estimated. Moreover, the investment on replacing incandescent lamps by energy efficient equipment is estimated and its financial returns evaluated. It is also revealed that there are many loopholes in the criteria used for selecting consumers for receiving the subsidy. The major shortcoming is that it allows unwanted people to enjoy the subsidy. It is seen that modifications are needed for the electricity subsidy eligibility criteria to ensure that only needy people receive the subsidy. Published on 2016-11-22 00:00:00
       
  • Effect of Fine Percentage on the Properties of Sub-base Material

    • Abstract: Finding sub-base material as per required specifications is a major issue in many parts of Sri Lanka. Therefore, in some cases, crushed stone is used as an alternative to sub-base material. Since good quality material is scarce, it is worthwhile to study the use of marginal materials to ensure sustainable development of the highway sector. The specification used in Sri Lanka for road constructions is the Standard Specification for Construction and Maintenance of Roads and Bridges (SCA/5) (SSCM) (ICTAD, 2009). Sub-base material is classified as lower sub-base material and upper sub-base material according to their Liquid Limit (LL), Plastic Limit (PL), Maximum Dry Density (MDD), California Bearing Ratio (CBR), and Sieve Analysis. A questionnaire survey was conducted among those engaged in the construction industry, to collect information on sub-base construction and on issues connected with the current specification relating to the passing percentage of the fine fraction. As a result, an experimental study was conducted by altering the fine fraction of soil from 0% to 40%. It was also verified whether the grading band of No.200 sieve passing can be relaxed up to a certain percentage if the soil sample satisfies the specified CBR, Plasticity Index (PI) value and swell percentage requirement. It was found that the proposed changes have been adopted in AASHTO and Road Note 31 specifications. Furthermore, linear regression models were fitted to assess the CBR of material in relation to fine fractions (percentage passing of 425 μm, 300 μm, 75 μm sieves). These passing percentages were identified as the most important percentages in predicting the CBR of the soil tested. Published on 2016-11-22 00:00:00
       
  • Decision Support Tool for Colombo Canal System Water Quality Monitoring

    • Abstract: Pollution of the Colombo Canal System, which is a complex network of open canals and marshes catering to the storm drainage needs of Greater Colombo, has been recognized as a major environmental issue. A Water Quality Monitoring Program is being carried out by SLLR&DC since 1997, where monthly measurements are recorded at 20 locations for 10 parameters. An attempt was made to integrate the raw data, an analysis of the water quality regime of each location, and a study of its relationship with canal water level and average monthly rainfall, by developing a simple, userfriendly computer package called the Water Quality Monitor (WQM). It will assist the user in decisionmaking, regarding the attainable level of quality for a particular site, and whether that quality level could be reached by varying the canal water level. It also provides a general idea on how much of the target quality is attainable with the dilution and flushing effect of rainfall. A special feature of WQM is the facility provided to analyse the user's own data sets, apart from the built-in Colombo data. This paper describes the rationale, methodology of development and the application of the software package of the 'Water Quality Monitor'. Published on 2016-09-30 00:00:00
       
  • Churn Management in Sri Lankan Mobile Market

    • Abstract: Churn is a measure of the number of subscribers who leave or switch to another carrier's service. The frequent migration of customers is in a way a threat to mobile operators as the expense on customer acquisition is greater than retention. On the other hand, for any operator it is difficult to maintain a steady growth in the market without maintaining the existing customers. Due to profound competition, controlling churn rate is becoming a challenge to Mobile Operators and identifying reasons for Churn is an even greater challenge as it is highly dependent on the values, culture, attitudes and perception of the different segments. The main causes for retention or churn from one network in Sri Lankan context (for different segments) are identified by a questionnaire evaluated across various demographic factors (Age, Education level, Monthly Income, Gender). The questionnaire was distributed among 400 mobile subscribers and received 305 responses which were used in the analysis set out in the paper to follow. Strategies that can be used to minimize churn rate is identified based on the feed back received in the questionnaire and by looking at best practices available in the region. Finally, Researchers developed a model to prioritize the influencing factors (Tariff, Coverage, Brand, VAS, and QOS) for overall customer satisfaction of Sri Lankan Mobile customers and checked whether there is any relationship with demographic factors and influencing factors for churn. In addition to that, researchers have suggested strategies that should be adopted by Sri Lankan mobile operators to minimize churn. Published on 2016-09-30 00:00:00
       
  • Rehabilitation Programmes of Large Scale Irrigation Projects - An
           Opportunity to Alter the Farmers' Role in Irrigation Water Management

    • Abstract: Past experience in Sri Lanka shows that a need for a major rehabilitation of irrigation systems arises at 20 to 25 Years cycle. Usually these rehabilitation programs are implemented by borrowing funds form international donors such as World Bank, EU, JBIC etc. However in time to come, the dependency on such outside funding sources is questionable in view of the trends in lending criteria for countries such as Sri Lanka. Therefore it is very essential to plan such rehabilitation programs guarant long term self-sustainability beyond the rehabilitation phase. One way to address this challenge is to introduce management tactics which would facilitate harnessing of human resources available within the farming community for the operation and maintenance of the irrigation infrastructure. If properly planned, the rehabilitation phase provide a good opportunity to initiate such a program. This paper describes a Water Management Programme (Water Quota system) which was implemented in System H of the Mahaweli Project with the objective of tapping the human resources available within the Farming Community strategically to address the challenge. This program was implemented during 1998-2003 as a parallel activity with a rehabilitation program under Mahaweli Restructuring and Rehabilitation Project (MRRP) in System H of Mahaweli Project As a result of this program water duty drops down with time after the year 2000 (Year of introducing the Water Quota System). Within 4 Years period from 2000, average water duty came down to 0.85 Meters from 1.2 Meters. Published on 2016-09-30 00:00:00
       
 
 
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