http://ir.lib.ruh.ac.lk/handle/iruor/7470 2026-05-09T11:13:23Z 2026-05-09T11:13:23Z Arunakumara, K.K.I.U. http://ir.lib.ruh.ac.lk/handle/iruor/11527 2024-10-11T04:01:35Z 2011-01-01T00:00:00Z

Use of Crop Plants for Removal of Toxic Metals. Arunakumara, K.K.I.U. Phytoextraction is an environmentally sound and cost-effective technology for cleaning up soils contaminated with toxic metals. The success of phytoextrac tion depends on the ability of plants to produce large amounts of biomass. In addi tion, plants must be tolerant to the target metals and be efficient to translocate metals from roots to the aboveground organs. The effectiveness of phytoextraction also depends upon site and metal species. However, the amount of metals extracted by plants is basically decided by (1) the metal concentration in dry plant tissues and (2) the total biomass of the plant. Certain varieties of high-biomass crops have been found to have the ability to clean up the contaminated soils. The major advantage of using crop plants for phytoextraction is the known growth requirements and well established cultural practices. One of the most promising, and perhaps widely studied crop plant for the extraction of heavy metals is Indian mustard. Other crops like sweet sorghum, oat, barley, maize, and sunflower are also reported to accumulate toxic metals. As established cultural practices may not elicit the same plant response as observed under non-contaminated conditions, attention must be paid on develop ing suitable agronomic practices to optimize the growth of plants even under con taminated conditions. Further, a coordinated effort is required to collect and preserve germplasm of accumulator species where molecular engineering can play a key role in developing engineered plants capable of cleaning up contaminated soils and commercializing phytoextraction strategies

2011-01-01T00:00:00Z Muthumala, C.K. De Silva, S. Arunakumara, K.K.I.U. Alwis, P.L.A.G. http://ir.lib.ruh.ac.lk/handle/iruor/11501 2024-10-09T05:19:47Z 2018-01-01T00:00:00Z

Identification of joint efficiencies in 13 mm finger jointed timber species used in Sri Lanka. Muthumala, C.K.; De Silva, S.; Arunakumara, K.K.I.U.; Alwis, P.L.A.G. When using timber in construction and the furniture manufacturing industry, waste timber materials and short length sections of timbers which are dumped by sawmills are considered to be matter of concern. ‘Finger joint’ is a recognized technique connecting two small pieces of waste timber together to ensure their sustainable utilization. Currently, the technique is used in Sri Lanka for non- structural purposes such as making timber boards and furniture. However, issues related with the strength of the joints have not fully investigated in Sri Lanka. This study was undertaken to determine the tensile strength performance of seven timber species in both unjointed (clear) and finger-jointed methods with 13mm finger pitch. An SWR adhesive (PVA) type was used as bonding material at normal exposure conditions. Well-seasoned Grandis, Jack, Kumbuk, Mahogany, Pine, Satin and Teak timber materials were used for the study. BS 373: 1957 and BS EN 15497:2014 were used as standards for tests. The tests for tensile properties were performed using the Universal Testing Machine (UTM 100 PC) with a loading plate moving speed of 01mm/min. Maximum load was read on graph to calculate the ultimate tensile strength. The highest ultimate average tensile strength values were recorded in control specimens and different joint efficiencies were recorded in different finger jointed species. The highest mean finger joint efficiency percentage was obtained from Mahogany timber species and the least mean finger joint efficiency percentage was recorded in Kumbuk timber species.

2018-01-01T00:00:00Z Muthumala, C.K. De Silva, S. Arunakumara, K.K.I.U. Alwis, P.L.A.G. http://ir.lib.ruh.ac.lk/handle/iruor/11498 2024-10-09T05:21:27Z 2020-01-01T00:00:00Z

Investigation of the Relationship Between Densities Versus Mechanical Properties of Sri Lankan Timber Species. Muthumala, C.K.; De Silva, S.; Arunakumara, K.K.I.U.; Alwis, P.L.A.G. The aim of this study was to investigate the relationships among wood density, modulus of rupture (MOR), modulus of elasticity (MOE), compression parallel to grain (CNP) and compression perpendicular to grain (CPG) in 32 timber species grown in Sri Lanka. Defects free stem section from each timber was taken at the breast height and samples were prepared according to BS 373: 1957 standard. The tests for mechanical properties were performed through the Universal Testing Machine (UTM 100 PC). Linear Regression Analysis was done for interpreting the effectiveness of the relationship in wood density with other mechanical properties (MOR, MOE, CPG, CNG). The relationship between wood density and mechanical strength properties were analyzed by regression models.Wood density showed strong positive relationship with CPG and MOR. Results in the regression test revealed a significant relationship (P = 0.001) among wood density and other mechanical prop erties such as MOR, MOE, CNP and CPG. These results can be used for developing effective timber classification system in Sri Lanka

2020-01-01T00:00:00Z Muthumala, C.K. De Silva, S. Arunakumara, K.K.I.U. Alwis, P.L.A.G. http://ir.lib.ruh.ac.lk/handle/iruor/11493 2024-10-09T05:20:53Z 2020-01-01T00:00:00Z

Investigation of the Best Joint Type for Combining of the Finger-Jointed Timber Panels in Board Production. Muthumala, C.K.; De Silva, S.; Arunakumara, K.K.I.U.; Alwis, P.L.A.G. Waste sawn timber material in furniture factories and short length of sawn timber are serious problems in timber industry. To further suggest ways to minimize the waste, by applying a jointing system, this paper utilizes the finger-jointed tech niques. Using this method, waste timber planks, trimmings and edgings can be used as finger-jointed boards and furniture in sustainable way. Finger joint technique is also used to eliminate wood defects which weaken the strength of sawn wood planks. Finger joint technology is used in structural and non-structural applications. Furniture mainly belongs to non-structural category. This study was conducted to investigate the best joint type for combining of the finger-jointed timber panel in board produc tion. Shear test was done to determine the most suitable joint type which could be employed in combining two finger-jointed timber panels. Shear test was performed for Pine—Pinus carebaea (soft wood) and Teak—Tectona grandis (Hard wood) timber types. Clear specimens, butt-jointed and tongue and groove were tested in the shearing apparatus. Eight test specimens of each timber specimens were used to obtain shear strength perpendicular to grains with 0.5 mm/min loading rate was applied using a Universal Testing Machine. Shear strength of Teak specimens with tongue and groove is higher than Teak specimens with butt joint, because bonding area of the tongue and groove specimens is higher than bonding area of the butt jointed specimens. Specimen part with tongue of Pine is weaker than corresponding part of butt-jointed Pine specimen due to small cross-sectional area of tongue. So, Shear strength of Pine specimen with butt joint is greater than Pine specimen with tongue and groove.

2020-01-01T00:00:00Z