Engineer : Journal of the Institution of Engineers, Sri Lanka
Open Access journal
ISSN (Print) 1800-1122
Published by Sri Lanka Journals Online [45 journals]
- Causes of time overrun in construction phase of building projects : a case
study on Department of Engineering Services of Sabaragamuwa Provincial
Abstract: The main purpose of this study is to identify the significant causes of time overrun in construction phase of building projects handled by the Department of Engineering Services (DOES) of Sabaragamuwa Provincial Council (SPC) and to propose mitigative measures. The preliminary investigation of this research revealed that 80% of the building projects handled by the DOES are not completed within the agreed contract period. The study determines 51 factors causing time overrun in the context of the DOES, which is the basis of the study. The perceptions of clients, consultants and contractors regarding frequency of occurrence and severity of these factors were obtained using questionnaire. Using the indices of frequency, severity and thereby the indices of significance were computed for all the factors. ‘Rainy weather’, ‘poor liquidity of the contractor’ and ‘inaccurate planning and scheduling of projects are identified by all parties as the most significant factors causing time overrun. According to the views of both clients and consultants, ‘contractor related factors’ are the most significant causes of time overrun. As for the degree of agreement of perceptions on delay causes. the highest is between clients and consultants (68%) and the lowest between the contractors and clients (50%). Finally, the research makes propositions separately for each party in the contract in order to mitigate the respective contribution towards time overrun.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6780 ENGINEER, Vol. 46, No.03, pp. 9-18 2013 Published on None
- Characteristics of hydraulic jumps over rough beds – an experimental
Abstract: The present knowledge on the behaviour of hydraulic jump is only for smooth, horizontal channel beds and very limited studies have been reported in literature on the performance of hydraulic jumps on rough beds. This research attempts to investigate the characteristics of hydraulic jumps formed on rough, horizontal channel beds under different flow conditions using laboratory investigations. A series of experiments were carried out in a rectangular flume which consists of artificially roughened beds formed by placing rectangular wooden strips in specific intervals. The hydraulic parameters such as, initial water depth, sequent water depth, and flow rate were measured for different bed roughnesses. The analysis of experimental data showed that the rough bed reduces the distance to the jump from the gate and the sequent depth ratio than those on smooth beds while creating a high energy loss. With the availability of a large number of experimental data on hydraulic jumps over rough channel beds, mathematical formulations were developed to express the hydraulic jump characteristics relating roughness parameters such as; roughness density and roughness height.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6779 ENGINEER, Vol. 46, No.03, pp.1-7, 2013 Published on None
- From the Editor
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6771 ENGINEER, Vol. 46, No.03, pp. III, 2013 Published on None
- A multi-tenancy aware architectural framework for SaaS application
Abstract: In the era of cloud computing, multi-tenant based Software as a Service (SaaS) applications have been widely identified as the next generation of cloud applications. SaaS allows multiple user organizations to customize an application in a reliable and secure manner. However, this customization is a complex and error prone exercise. In response, researchers and practitioners have come up with SaaS architectures based on frameworks, platforms and modelling approaches to ease the complexity of SaaS application development. However, these methods and tools have not focused on aspect of development methodology being tuned to support long-term maintenance of the SaaS application. This paper presents an architectural framework for SaaS application development that incorporates long-term maintenance requirements arising from multi-tenancy of the application. It consists of a methodology coupled with a tool chain, which brings multi-tenancy aware features to develop SaaS solutions that meet critical architectural requirements. It also includes a UML 2.0 based Profile named SaaSML for designing of main components, a skeletal framework to position these components and a methodology for benchmark evaluation of key design criteria.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6782 ENGINEER, Vol. 46, No.03, pp. 21-31 2013 Published on None
- Universal science : part II
Abstract: This paper is an outcome of a trial carried out to find a common methodology to address the different subjects together using circular thinking pattern which is borrowed from Buddhism rather than addressing them separately. In addition to this , Buddhism which comprises of the perfect structure ,immense innovative power and the broader ways of knowledge gaining are also utilized here to combine the subjects together . Being pre-qualified with a (spiritual') birth, Universal Science shows how to overcome the limitations of the present science as the only solution. In this context, US as a concept is emphasized here as the method of reaching climax and achieving maximum benefits without falling to troubles in contrast to the present science & shows that the pattern (circular)thinking together with Buddhist concepts will form the next generation (and end phase') of science. Through this paper, for the first time here, it is proposed, to identify US as the new finding of the lost (indigenous) science during invasion , that was followed by the ancestors in the past, and which was being sought for long by the patriotic through out past few decades. Prior to this finding, innovative power of Buddhism has also been revealed by introducing five methods of inventions while raising this as the only culture in the world, having qualified with self innovative powers as a unique identity ,as two more new findings. Hence delaying for so long the finding of the lost science is deemed to be due to the delay in identifying the un-imaginable innovative power of Buddhism as above by the present society, of which is behind all these innovative scenario. It further claims that the methods of new innovations as the engine of the US which drive the same towards far reaching areas. This paper shows the US as the absolute and authentic path for the development of Sri Lanka in the light of ,due to a fast science for the balance development of any country while more than being the heritage, in line with the fore-fathers.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6783 ENGINEER, Vol. 46, No.03, pp. 33-42 2013 Published on None
- Suggested Improvements on Water Treatment Plants for Sustainable
Abstract: Water is a basic human need and acquisition of safe drinking water is a major problem faced by present world. Water treatment plants are used to purify the water in to a quality suitable to be consumed by humans. Though there are a large number of Water Treatment Plants operating in Sabaragamuwa Province of Sri Lanka most of them are facing common problems which reduce their capacity and decrease their efficiency. In an average plant of capacity between 1000-10,000 m3/day, the capacity should be improved by 21% to provide the existing demand. Sand/gem mining, problems due to floating debris, difficulties in maintenance, insufficient storage facilities, the implemented mechanisms not being suitable for the process, difficulties in maintenance and environmental degradation in the catchment areas are common problems faced by these plants. Key suggestions to improve Water Treatment Plants in Sabaragamuwa Province are to form plants with larger capacities to an area, to leave space for necessary augmentations when building plants, implementing strict actions on sand/gem mining within 2 kilometers from an intake, prevent floating debris to the plant, provide sufficient storage and to conserve catchment areas.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6786 ENGINEER, Vol. 46, No.03, pp. 69-73 2013 Published on None
- Computational Fluid Dynamic (CFD) simulation of flow around tall buildings
Abstract: Significant improvements of computer resources in recent past years allow to use computational fluid dynamics (CFD) methods as an alternative test method for wind tunnel tests in various wind engineering aspects. However the accuracy of CFD simulation mainly depends on careful setup of three main components of a CFD simulation, which are domain size, adopted mesh, and boundary conditions. This paper presents basic theoretical background of use of CFD for atmospheric boundary layer simulations and proper methods recommended for creating domains and meshes for CFD models. It also demonstrates several empirical methods that can be used as boundary conditions in the absence of more accurate data for simulation. The CFD simulation results of pressure distribution of 112m tall buildings is compared with the wind tunnel test results and found that performance of those empirical methods is satisfactory. The use of CFD simulation for flow visualization around a tall building and evaluating pedestrian level wind velocities are also demonstrated in this paper.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6784 ENGINEER, Vol. 46, No.03, pp. 43-54 2013 Published on None
- Mathematical modelling of watershed wetland crossings for flood mitigation
and groundwater enhancement – case of the Attanagalu Oya river basin
Abstract: Recurrent flooding mostly experienced in urbanized lower floodplains is a major problem faced by many of the river basins. In the developed countries, flood retention/detention is effectively practiced as a flood management option which also enhances groundwater recharge. However, this approach requires sufficient land with provision for storage and acquisition of land for incorporation of these facilities is a major issue in built up areas. Present modelling work analysed the possibility of utilising the distributed temporary storage zones that exist at wetland crossing locations of the road network. The mathematical model calibrated and verified for the Attanagalu Oya watershed of Gampaha District at Karasnagala and extended to the outlet at Ja-ela, investigated the possibility of storage enhancement by raising the road surface together with an engineered drainage structure to detain the floods. Model simulations for the rainfall event of May 2010, revealed that the trial interventions of 0.3 m road formation level increase with a 0.2 m drainage outlet sill level increase at feasible wetland crossings lead to a 14.2% reduction in peak flow while the enrichment of groundwater was 8.7%, and the flooded area reduction at Ja Ela/Elenegoda exit point was 9.2%. This demonstrated that a network of engineered wetland crossings provides an eco efficient infrastructure solution for sustainable management of floods and groundwater enhancement.
DOI : http://dx.doi.org/10.4038/engineer.v46i3.6785 ENGINEER, Vol. 46, No.03, pp. 55-67 2013 Published on None
- From the Editor
DOI : http://dx.doi.org/10.4038/engineer.v46i4.6798ENGINEER, Vol. 46, No.04, pp. III, 2013 Published on None
- Factors Influencing the Service Life of Buildings
Abstract: The service life of a building depends mainly on its chief structural materials and the environment it is placed in. This paper collates the evidence from condition surveys conducted on some buildings with ages of up to 125 years set in a humid tropical environment, and seeks to arrive at some generalizations. Load bearing masonry walls and timber floors had performed well, as had exposed steel sections that were well maintained. Buildings with such elements could be expected to last well beyond the ‘normal’ design life of 60 years. If a reinforced concrete building had been exposed to a chloride source, major repairs were required after just half this design life. Carbonation depth was found to broadly obey a correlation with the square root of time. However, it is shown that both depths of carbonation and surface chloride levels can vary considerably in different parts of the same building. These findings have direct implications for both construction (in the choice of materials) and inspection (with respect to sampling and use of multiple test methods).
DOI : http://dx.doi.org/10.4038/engineer.v46i4.6801 ENGINEER, Vol. 46, No.04, pp. 1-7, 2013 Published on None