Faculty of Engineering, Earth Resources EngineeringTheses / Dissertations submitted to Department of Earth Resources Engineeringhttp://dl.lib.uom.lk/handle/123/512024-03-28T12:10:45Z2024-03-28T12:10:45ZDevelopment of a land use/cover monitoring system using satellite imagesJayakody, JAShttp://dl.lib.uom.lk/handle/123/190532023-11-22T22:02:04Z2004-01-01T00:00:00ZDevelopment of a land use/cover monitoring system using satellite images
Jayakody, JAS
Remote Sensing and Geographical Information System are modem tools for ecosystem management. Remotely sensed data gives convenient and rapid solutions to problems in a variety of applications. Land is limited, and vital as it is the main provider of important natural resources. The fast growing human population has created many problems, due to the increasing demands for food, water, shelter and fuel. Thus such socio-economic factors often dictate how land is used regionally. Land use affects land cover and in turn, changes in land cover affect land use. Thus land plays a major role in any development process. In tropical countries, due to the impact of human beings, the rates of change in vegetation cover and land use are high. Hence frequent updating of land use maps is necessary to provide the information needed by planners and politicians. The main objective of this research is to investigate the possibility of using different remote sensing satellite images for developing a land use/cover monitoring system. This research is carried out in an area of approximately 400 square kilometres in the southern part of Sri Lanka. Imageries of SPOT, IRS and Landsat satellites are used. Different colour combinations are prepared and false colour composite images are used for image processing. Maximum likelihood method is used for image classification and the overall accuracy of the classifications is more than 90%. Using this classification, change detection matrices are developed to give changes for every land use class considered. A primary problem encountered in the study area is the mixed pixels. It is difficult to separate crop land from residential area, as some people reside in houses within the cultivated area. Filtering techniques can only partially remedy this problem. In order to monitor the land use/cover, image differencing method is applied and the extent of the detected changes in terms of pixels or hectares is calculated. A procedure is proposed as the land use/cover monitoring system using satellite images. Under this monitoring system, the extent of land use/cover changes can be computed by using different satellite images with varied spatial and spectral ranges.certainty.
2004-01-01T00:00:00ZAppraisal of heat treatment of "GEUDA" gemstones using gas- fired and electrically operated furnaceJaliya RGChttp://dl.lib.uom.lk/handle/123/186532024-01-12T08:52:42Z2021-01-01T00:00:00ZAppraisal of heat treatment of "GEUDA" gemstones using gas- fired and electrically operated furnace
Jaliya RGC
“Geuda” gemstones are less valuable corundum variety that has the potential to alter into blue sapphire. “Geuda” is found abundantly in Sri Lanka and it is translucent to opaque corundum with a milky or silky appearance in reflected light and brownish honey colour (or diesel colour) in transmitted light with a basic body colour of a bluish, yellowish or reddish colour. At present, Sri Lankan gem industry commonly adapts gas-fired furnaces for heat-treating “Geuda”, to obtain the desired blue colour, yet recently introduced electric furnaces have also shown potential. It is widely believed that electric furnaces are superior to gas furnaces in achieving the anticipated colour, yet no proper evaluation has been done in this regard. Thus, revealed the optimum conditions and the colouring mechanism for electric furnace heat treatment compare to gas furnace heat treatment, twenty (20) “Geuda” samples were selected and each stone is cut into three similar pieces to compare the colour changes more accurately. The “Lakmini” furnace was used as the gas furnace and the maximum chamber temperature used was 1750oC with a soaking time of 30 min under reducing environmental condition inside the gas furnace. Electric heat treatment carried out at three different temperatures (1300oC, 1500oC,1700oC) and with different soaking times (three days, five days, ten days and one month). Colour enhancement after heat treatment was observed using the GIA colour grading system. Samples were subjected to XRD, FTIR and UV-visible spectrum analysis before and after the heat treatments and XRF for the identification of elements present in the gemstones.
The optimum colour alteration occurred in combined heat treatment (1700oC in electrically operated furnace after gas furnace at 1750oC, 30 min). There was a significant peak height drop at 3309 cm-1 in FTIR spectroscopy after the thermal treatment in all samples tested. This peak height drop corresponded to O-H stretching mode water molecules inside “Geuda” stone and it was imperceptible with one month of soaking time. The UV-Visible analysis showed a peak development after heat treatments at 550 nm-650 nm. This is due to the development of blue colour inside the stone as a result of the formation of [FeTi]+6 complex and it was conspicuous in combined heat treatment. d-spaces of the lattice structure in the “Geuda” stones have changed in the stones when analyzed using XRD. XRF analysis emphasized that the Fe:Ti ratio is a critical determiner of blue colour development with combine heat treatment. Geuda stones with a Fe:Ti ratio of 1:7 to 1: 13 produced the desired blue colour. Presence of increased Ti in the stone produced a dark blue colour. The results reported in this study suggest the method of heat treatment, Fe:Ti ratio of the stones and reduced environment inside the furnace are the critical determiners of blue colour development in geuda gemstones.
2021-01-01T00:00:00ZEffectiveness of emulsion explosives in quarrying in high grade metamorphic rocks in Sri LankaPathirana, KPRhttp://dl.lib.uom.lk/handle/123/158482023-07-12T09:33:16Z2017-06-01T00:00:00ZEffectiveness of emulsion explosives in quarrying in high grade metamorphic rocks in Sri Lanka
Pathirana, KPR
In mining, blasting is the predominant method adopted for breaking consolidated rocks with the main objectives being extraction of minerals at minimum cost with minimum damage to the environment. Explosive is a compound or a mixture of compound which is capable of undergoing extremely rapid decomposition with deflagration or detonation. When the explosive reaction takes place radial cracks are form by as a result of detonation pressure with fragmentations followed by gas pressure. The optimization of explosive usage in Sri Lankan metamorphic rock is the main objective of this research. The detonation velocity of the explosive should match, as closely as possible, the sonic velocity of the rock to be blasted of rock. The rock's sonic velocity is a reliable indicator of its structural integrity and resistance to fragmentation. With varying rock types, sonic velocities vary with varying structural formations. Aggregate impact value is one parameter of hardness of rock. This study is conducted by considering the aggregate impact value as the indicator of hardness of rock. Test is planned, keeping blasting parameters constant namely hole diameter, explosives charge, burden, spacing and stemming against the different rock types with different aggregate impact values. The efficient use of explosives, along with the proper selection, will be the key to a successful blasting program. After comparison of the results of production rock volume and fragmentation formulate the explosives usage to get the optimum results that how explosives behave with the different rock types with different aggregate impact values or hardness. Dautrich method is the first time practically used in Sri Lankan field to determine the velocity of detonation of emulsion explosives in this research. This method is indirect field test method for suggesting VOD of explosives and the determination of the VOD is based on the fact that processes that propagate at different linear velocities travel different distance, in the same time interval. According to the blast results harder rocks fragmented with emulsion explosives, higher production volume were obtained than less hardness rocks. Increasing the hardness, increasing the production rock volume. Therefore, the relationship with hardness of rock and emulsion explosives usage is observed. Fly rock throw is more important to safety of blasting. This research indicates that fly rock distance is higher with AIV values more than 27. This result clearly indicates that emulsion explosives is very suitable for Sri Lankan metamorphic hard rocks.
2017-06-01T00:00:00ZEffect of trenching on blast-induced ground vibration in sri lankan metal quarriesSamarakkody, SATIhttp://dl.lib.uom.lk/handle/123/141762023-10-23T04:56:59ZEffect of trenching on blast-induced ground vibration in sri lankan metal quarries
Samarakkody, SATI
Problems due to ground vibration are a matter of serious concern for the users of
explosives. It is not possible to eliminate vibration completely or to contain them at
the source. Effort need to be made in controlling them within safe level, without
effecting the production schedules and economic viability of the project. When
predicted or monitored vibration exceeded the statutory limit, ground vibrations
are generally controlled by modifying the blast design parameters. In critical situation,
digging a trench has reduced ground vibration. The extent to which it can reduce ground
vibration has been examined by field experiments at a open cast quarry mine located
at Arankele in Sri Lanka.
After selecting a suitable quarry site at Arankale off
Kurunagala in North-Western province of Sri Lanka. Suitable place for blasting face,
digging a trench and observation point have been identified.
Vibration measurement were carried out after single
shot hole blasting method prior to digging a trench and after digging the trench with
variation of depth of drill holes and depth ofthe trench, at points located just before the
trench(A), just after the trench (B) and approximate observation point away from the
trench (C).
Average often single shot hole blast carried prior to digging
trench show ground vibration reduction percentage are 6.326% ,1.23%, 7.023% and
18.309% at B, and 72.262%, 54.474%, 55.183%, and 45.191% at C.
Results after digging the trench show ground vibration
reduction percentages are 57.878%, 53.946%, 40.514% and 36.757% at B and 55.509%,
64.787%, 56.848% and 42.382% at C.
Such results indicate, just after the dug trench, ground vibration reduction level is very
much higher compared to the results obtained before digging the trench. However
considerable deferences have not been observed at the observation point under same
condition. The results also show that the percentage of the reduction depend on the
trench depth to blast hole depth ratio.