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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  [47 journals]
  • Evaluation and Selection of Tools for Data Migration from Non-Spatial to
           Spatially Referenced Software – A Case Study Migration from MySQL to
           PostgreSQL

    • Abstract: Geographic Information Systems and open source software are becoming more and more popular resulting in an increased requirement for data migration from common non spatial software to spatially referenced software. MySQL is a very popular open source Database Management System used by most web developers but without support for spatial referencing. PostgreSQL is an open source software that supports Geographic Information Systems. It is often necessary to migrate data from MySQL to PostgreSQL and it is possible to identify many tools that are capable of executing the desired task. Therefore best available tool should be selected to ensure that the selected tool satisfies the main functionalities expected of the software and capabilities of performing the tasks with user friendly features. This paper describes a systematic methodology adopted to select the best free tool for data migration from MySQL to PostgreSQL using literature and rational judgement incorporating a qualitative ranking system to Migrate the base data. For easy comparison, an Evaluation Score of Tool was defined by calculating the percentage of available functionality when compared with the user desires for satisfaction. After comparing three available tools, Postgres Plus 8.3 free software was identified as the best with a Evaluation Score of Tool value of 76%. The present work identified 3 main and 11 sub database functions together with 4 main and 13 sub components of Graphical User Interface functionality as important parameters for data migration.

      Published on 2016-05-02 00:00:00
       
  • An Application of Distributed Hydrological Model, YHyM/BTOPMC to Gin Ganga
           Watershed, Sri Lanka

    • Abstract: Modelling approach is a useful tool which provides information on spatial distribution of basin hydrologic components. In that context distributed hydrological models play a vital role in efficient planning and managing water resources systems. But their applications are partly limited due to the requirement of large amount of data which are not always available and difficulties in obtaining such data due to bureaucratic constraints. Global public domain data sets have become increasingly available on the internet and it is appropriate to make use of such data which can often be supplemented for ground-based data. The objective of this study is to investigate the applicability of the distributed hydrological model, YHyM/BTOPMC to simulate the major hydrological characteristics in Gin ganga watershed utilizing the global data sets readily available in public domain along with the local available rainfall and discharge data. Gin ganga is a river which is one of the main sources of water supply to the southern region of Sri Lanka. It’s catchment entirely lies within the wet zone of the country and frequently subjected to flooding during the rainy seasons. Hence, it is vital to comprehend the hydrology of the watershed in order to gain knowledge on current and future hydrological conditions. In the study, YHyM/BTOPMC model performance was evaluated by the Nash-Sutcliffe Efficiency (E) and the volume ratio of simulated discharge to observed discharge (Vr). The results show that the overall hydrological behaviour of the Gin ganga watershed is adequately simulated by the model. Further the results are discussed in the context of how the model simulation results replicate the temporal variation of basin hydrological characteristics such as ground water saturation deficit, soil moisture states, base flow etc.


      Published on 2016-05-02 00:00:00
       
  • Flood Inundation Mapping along the Lower Reach of Kelani River Basin under
           the Impact of Climatic Change

    • Abstract: The downstream low lying region of the Kelani River including the Colombo suburbs, experience severe inundation due to heavy rainfalls in the upper basin of the Kelani River. Occurrence of heavy rainfalls is expected to be more frequent in the tropics with the impact of climatic change (IPCC, 2007). Therefore, understanding future rainfall intensity in the river basin and inundation in the low lying region along the lower reach of the Kelani River is extremely important as this is a region with a high population density and economic activities in the suburbs of the capital. The present study analyses the potential extreme rainfalls and resulting flood inundation along the lower Kelani River. Coarse grid atmospheric parameters provided by Global Climate Model (GCM) models for A2 (high emission scenario) and B2 (low emission scenario) scenarios of Intergovernmental Panel on Climate Change (IPCC, 2007) were downscaled to local scale by applying Statistical Downscaling Model (SDSM). Flood discharge and inundation along the Kelani River reach below Hanwella were analyzed by applying two-dimensional flood simulation model (FLO-2D). Inflow to the model at Hanwella, is estimated by the Hydrologic Engineering Center – Hydrologic Modeling System (HEC-HMS) model under future extreme rainfall events. Areas vulnerable to inundation under the above climatic change scenarios are presented. Published on 2016-05-02 00:00:00
       
  • Performance of Tall Buildings with and without Transfer Plates under
           Earthquake Loading

    • Abstract: The scarcity of valuable lands has created a leap in the tall building construction all over the world. Due to the mixed use of these buildings as commercial, residential, parking, etc., it has become essential to have different column grids in the same building to ensure the efficient use of space and materials. Use of transfer plates is one of the widely used methods to transfer gravity loads among different column grids. With lateral loads governing the design of tall buildings, it is essential to consider their behaviour against earthquake loads. This paper compares the behaviour of tall buildings with and without transfer plates against earthquake loading. Published on 2016-05-02 00:00:00
       
  • Mortar Consumption Characteristics of ‘Brickwork’ and a
           Framework for Managing Brick and Mortar Walls in Chaotic Environments

    • Abstract: This study investigated how bricks and mortar could be used in a chaotic environment where brick and joints sizes could be varied to achieve better outcomes (such as cost minimisation) through an understanding of mortar consumption characteristics of brickwork. This was made possible by integrating three innovative concepts, viz. ‘type’ of wall, ‘cost polarity’, and ‘bricks to mortar’ ratio. New formulae for computing mortar volumes had to be developed as the simple formula of subtracting the volume of bricks from the volume of wall that did not produce accurate mortar volumes. Having validated these formulae, mortar volumes in different joints were computed. Accordingly, it was found that the bed-joint accounted for the largest portion of mortar in single brick thick walls in English bond, irrespective of the size of brick used. With more than two thirds of the total volume of mortar in the bed joint (even with a smaller bed joint of 10mm), it plays a significant role in changing the volume of mortar in brickwork. As the volume of mortar in the study walls was as high as 73% when compared with (less than) 25% for walls with standard brick and joint sizes, the very notion of what ‘brick-work’ was challenged. This led to the identification of three ‘types’ of walls, namely, ‘mortar-wall’ (with volume of mortar over 50%), ‘brick-mortarwall’ (with volumes of mortar between 25-50%), and ‘brick-wall’ (with a volume less than 25%) with corresponding ‘bricks to mortar’ ratios of less than 1, 1 to 3, and greater than 3. This classification was used for specifying a ‘type’ of wall. It was found that ‘brick to mortar’ ratio was quite sensitive to variations in small values of the bed joint when large bricks were used though this was not the case with smaller bricks and larger bed joints. This suggests the importance of controlling workmanship if the ratio is to be maintained at small values of bed joint. A strategy-map for selecting a desirable 'bricks to mortar ratio’ was provided based on ‘type’ of wall, brick and joint sizes, and degree of control required for ensuring workmanship. In order to make strategic decisions on costs, the concept of ‘cost polarity’ (cost of density of bricks to mortar) was used. Accordingly, a cost-efficient ‘type’ of wall could be selected based on whether cost polarity was less than 1 or greater, using a strategy-map for such decision making. Further savings in costs could be achieved by using the strategy-map for ‘brick to mortar’ ratios whilst giving consideration to the build ability of the bed joint, and sizes of other joints including joint fullness. The framework thus proposed provides a fresh perspective on how walls built with bricks and mortar could be managed (particularly in Sri Lanka) with potential for enormous cost savings using a chaotic environment to bring a new order. Published on 2016-05-02 00:00:00
       
  • Characteristics of Masonry Blocks Manufactured with Rice Husk Ash (RHA)
           and Lime

    • Abstract: Rice husk is one of major agro-waste material in Sri Lanka. Rice Husk Ash (RHA) is produced by burning Rice husk as fuel in brick kiln. Rice husk ash produced by burning at high temperature contains pozzolanic constituents. In Sri Lanka, cement is extensively used to manufacture masonry blocks, although the cost of cement is high. Because of having highly pozzolanic constituents in RHA, it can be used as a building material, instead of cement, to produce cement sand masonry blocks. It was frequently reported that compressive strength of RHA based blocks increases with increasing the RHA content up to 5% and further addition of RHA causes to decrease in compressive strength. In this study, an attempt is made to increase the utilization of RHA by adding Ca2+ to the mixture. Solid masonry blocks, having the size of 360 mm x 100 mm x 170 mm, were cast with the mix proportion of 1:6 Cement - Sand. Blocks were manufactured in two series. In the first series, RHA was used as addition with respect to weight of cement. In this series, four different RHA contents (i.e., 0%, 5%, 10%, and 15%) were used with constant lime content (10%). In the second series, RHA was used as partial replacement for cement with four different RHA contents (i.e., 5%, 10%, 15% and 20%) with constant lime content (10%).The blocks were tested for 7, 14 and 28 Day compressive strength. With the presence of lime (10%), the optimum 28 Day compressive strength was found at the level of 10 % RHA. When RHA was used as addition, the optimum 28 Day average compressive strength of block was found as 4.937 N/mm2. When RHA was used as partial replacement for cement, 28 Day average compressive strength of block was found as 3.467 N/mm2. Thermal performances of the RHA lime based blocks were also investigated. It was found that thermal conductivity of RHA lime based block was lower compared with that of the conventional block. The RHA lime based blocks showed better structural and thermal performances. Increased use of RHA will reduce the unit cost of masonry block while improving sustainability. Published on 2016-04-28 00:00:00
       
  • From the Editor Vol. 45(3)

    • Abstract: ENGINEER, Vol. 45, No. 03, pp. III, 2012 Published on 2016-04-28 00:00:00
       
  • Treatment of Seepage through Vendarasankulum Twin Reservoir in Eastern Sri
           Lanka - Cost Comparison of Alternative Techniques

    • Abstract: The purpose of this study is to select a more effective technique from ‘upstream cutoff’ and ‘grouting treatment’ for the control of seepage through the Vendarasankulum reservoir. Using engineering judgment, empirical and theoretical knowledge, trapezoidal cross sectional dimensions of layers of different soil materials were determined. For example, the cross section at 490m (from left); SC layer on the U/S side slope has widths, 3m and 12m at bund top and bottom respectively; clay layer in the core has widths 12 m and 3 m at the top and bottom respectively. The effective fetch (1.72 km) and thereby the maximum wave height (0.84m) were computed in order to extract values for thicknesses of riprap (0.45 m) and bedding layer (0.30m). Grouting treatment involves clay-cement grouting in the overburden and 6m deep cement grouting in the rock, requiring a total of 296 grout holes. While the estimated cost of construction of the upstream cutoff is SLR 30.3 million, the same for grouting treatment is SLR 11.3 million, indicating the former option would cost 168 percent more. Therefore, grouting treatment is more economical and sufficient, although upstream cutoff could offer better seepage control. Published on 2016-04-28 00:00:00
       
  • From the Editor Vol. 45(2)

    • Abstract: ENGINEER, Vol. 45, No. 02, pp. III, 2012 Published on 2016-05-02 00:00:00
       
  • Key Issues of Data and Data Checking for Hydrological Analyses - Case
           Study of Rainfall Data in the Attanagalu Oya Basin of Sri Lanka

    • Abstract: Inconsistencies and non-homogeneities in the hydrological and meteorological time series could be identified by incorporating statistical tests that detect trends and change points. Inconsistency which reflects systematic errors during recording and the non homogeneity that arises from either natural or man made changes to the gauging environment are both important for adequate time series analysis. It has also been identified that statistical tests together with physical or historical evidence and justifications from metadata need to be incorporated for a very detailed study. A case study was carried out for the rainfall data of Attanagalu Oya basin in the western province of Sri Lanka with a data set consisting of six stations having daily rainfall data for 30 years. According to Pettitt test, a significant change around 1977 & 1985 at Karasnagala and Pasyala could be found. However Pasyala is the most significant station for the change of rainfall pattern, which was confirmed by t-test. Knowledge of Meta data was found very important in order to make necessary corrections to shifts identified through Double Mass Analysis. This paper shows that statistical tests and rational judgements would enable suitable corrections even though it is common to find that most of the hydrological and meteorological data are either flagged for quality or poorly documented. Published on 2016-05-02 00:00:00
       
 
 
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