http://ir.lib.ruh.ac.lk/handle/iruor/10270 Wed, 13 May 2026 18:38:06 GMT 2026-05-13T18:38:06Z https://ir.lib.ruh.ac.lk:443/xmlui/bitstream/id/70fe03d5-f05a-4eec-99ef-37b8a6895090/ http://ir.lib.ruh.ac.lk/handle/iruor/10270 http://ir.lib.ruh.ac.lk/handle/iruor/11180 Preliminary Pages Thu, 28 Jan 2016 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/11180 2016-01-28T00:00:00Z http://ir.lib.ruh.ac.lk/handle/iruor/11179 Facing Future Challenges: Assessing the Role of Science and Technology in Climate Change Mitigation and Adaptation (Keynote Speech) Kopke, Soren Thu, 28 Jan 2016 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/11179 2016-01-28T00:00:00Z http://ir.lib.ruh.ac.lk/handle/iruor/11175 Effect of extra work and variations to the project cost: empirical evidence from Sri Lankan road construction industry Abeynayake, N.C.; Abeysooriya, D.P. Extra work and variations are two most important concepts that closely related with construction industry. At present extra work and variations is a common incidence happening in the construction industry. Simply Extra work and variations can be understood as any other work other than that has mentioned at Bills of Quantities. Extra work and variations may occur due to various reasons. It is obvious it will directly effect at Project cost. Expenses and Time are the main reasons that have to be considered in a construction project. If more time has to be spent on extra work and variations, it may be a definite disadvantage to the overall project cost. To minimize extra work and variations is very important for large scale projects as the project risk is also high. Hence finding the root causes for these two anomalies is much important to the construction industry. The factors which will be investigate can be used to take preventive measures in minimize these two variables even though this problem cannot be kept at the zero point. Thu, 28 Jan 2016 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/11175 2016-01-28T00:00:00Z http://ir.lib.ruh.ac.lk/handle/iruor/11174 Determination of surface tension of water and interfacial tension of water-kerosene interface by light diffraction Perera, H.A.D.S.D. Light diffraction by capillary waves, generated on the surface of a liquid is a very precise and none destructive method of finding the surface tension and other related physical parameters. In this research diffracted laser light patterns formed by the generation of surface capillary waves were used to find the surface tension of distilled water and the interfacial tension between thin kerosene films floating on distilled water as a function of film thickness. A pin attach to the diaphragm of a speaker was served as the exciter to generate surface capillary waves by the center of a dish which was filled with distilled water up to a certain level. A semiconductor laser (wavelength = 660 nm) was used as the coherent light source for the experiment. The diffracted light from the liquid surface was obtained on to a distant vertical wall, which served as the screen for the experiment. The diffraction patterns were observed by changing the oscillating frequency of the exciter pin. Obtained value of surface tension for distilled water was recorded as (0.0766 ± 0.0015) Nm-1 . By adding known amount of kerosene and following the same procedure the interfacial tension was calculated for several thicknesses (0.07, 0.14 and 0.21 mm) of kerosene film as 0.0470 ± 0.0022, 0.0404 ± 0.0025 and 0.0362 ± 0.0010 Nm-1 . The sudden drop in interfacial tension even for a slight kerosene film is observed and further study of film thickness against interfacial tension is proposed to model the effect of kerosene on natural water resources. Thu, 28 Jan 2016 00:00:00 GMT http://ir.lib.ruh.ac.lk/handle/iruor/11174 2016-01-28T00:00:00Z