Browsing by Author "Thanujan, T"

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item: Article-Abstract
Evaluation of machine learning algorithms in classifying multispectral imagery on waterbody extraction
(2021) Jayawardena, CL; Brinthan, K; Thanujan, T
A comprehensive study for utilizing multispectral satellite imagery to enhance novel environmental monitoring techniques is crucial in terms of accuracy, processing time, and cost for a sustainable triple bottom. The accurate classification of water bodies from other features optimizes spatiotemporal analysis to address global challenges. Therefore, this study emerges as the new research frontier in proposing an apt algorithm for recognizing water resources and coastline in Sri Lanka. This study explores the potential of using classification algorithms for geospatial assessments and applications with their accuracy and reliability. The acquired Collection 2 Level 2 Landsat 8 imagery was geometrically and radiometrically pre-processed, and a false-colour composite was produced from the bands: short-wave infrared, red and nearinfrared. A total of 280 training samples were created with the reference pixels of 50.13 percent for water bodies and 49.87 percent for other features. The confusion matrix was generated using a distinct set of 500 random points for each classification technique, and the F-score and kappa coefficient were calculated for the accuracy assessment. The study depicts that the supervised algorithms: Support Vector Machine, Maximum Likelihood and Random Trees, and unsupervised algorithm: ISO Cluster performs equally in classifying water bodies and other features with higher kappa coefficient exceeding 0.95. Out of these, ISO Cluster was efficient than other algorithms due to reduced handling time. The findings enhance the decision-making ability on extracting surface water bodies using freely available 30 m spatial resolution imagery.
item: Conference-Full-text
Evaluation of ventilation network through hybrid analytical-numerical approach in underground working block
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Thanujan, T; Brinthan, K; Thiruchittampalam, S; Jayawardena, CL; Dissanayake, DMDOK; Jayawardena, CL
The mine environment is complex and highly dynamic due to the developments over time and surrounding climatic changes. Heedlessness to supply adequate quantity and quality of air will catalyse short and long-term ailments to the workers. Therefore, this study emerges as the new research frontier in incorporating software-assisted numerical simulation with analytical computations. This investigation assesses the existing ventilation parameters at the Bogala underground graphite mine for the propriety of the working environment. The uttermost bottom block between 240 and 275 fathoms (FM) levels was examined. The parameters were obtained through the in-field ventilation survey. Measured air quantity, psychometry, and air quality values were analysed and fed to the computer-simulated model. Moreover, the reentry time for a development drive at 275 FM level was estimated using the throwback method. Adequacy assessment unveils that all the parameters besides air quality are inadequate at most stations for optimal mine conditions to attain maximum efficiency. Furthermore, the re-entry time after the development blast at the selected drive is meager and necessitates re-calculation for each blast. Moreover, stale air mixing and air recirculation are extant at 240 FM and 275 FM levels, respectively. Thus, mine ventilation at Bogala needs to be optimised, admitting workers' health, safety and comfort, and productivity of the mine.
item: Conference-Abstract
An investigation of industrial mineral mining methods in Sri Lanka
(Department of Earth Resources Engineering, University of Moratuwa, 2020-12) Thanujan, T; Subasinghe, MAIIJ; Vettinathan, S; Dharmaratne, PGR; Hemalal, PVA; Chaminda, SP; Jayawardena, CL; Dissanayake, DMDOK; Dassanayake, ABN
Sri Lanka is endowed with a rich base of industrial minerals despite its small land area. Traditional and modernized mining methods are employed to mine graphite, limestone, beach mineral sand (ilmenite, rutile, zircon and garnet), apatite, calcite, dolomite, quartz, feldspar, clay, kaolin, silica sand, mica and rock aggregate. Notably, some deposits have not been optimally exploited to their potential. Moreover, Sri Lanka does not have comprehensive information and documentation in the mining context. The mining method is selected on the basis of respective geology of the deposit, hardness of the ore and rock, depth, thickness and other geological aspects etc. The extraction of narrow steeply dipping vein deposits and deposits at great depth are significantly challenging and need specified selective mining techniques. In the study, currently practiced mining technologies, Cutand- Fill mining at Bogala, Open-stopping at Kahatagaha mines, open cast mining at Aruwakkalu Limestone quarry and mineral sand mining at Pulmoddai were investigated. The investigation was carried out through interviews and field visits. Site characteristics of each mine were tabulated, and the mining procedures were discussed. Mining methods employed at Kahatagaha and Pulmoddai were traditional while Bogala and Aruwakkalu utilize more systematic technologies. It is recommended to investigate and conduct indepth analysis in the second phase of the study for technological improvements.
item: Conference-Full-text
Smartphone vs. consumer-grade gnss for field studies: a statistical comparison
(IEEE, 2022-07) Jayawardena, C; Jayasundara, R; Thiruchittampalam, S; Thanujan, T; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Smartphones have replaced not only the telephone but also most other devices such as camera, computer, torch, Global Navigation Satellite System (GNSS) devices etc., used in our day-to-day activities due to their multifunctionality. However, the accuracy of the inbuilt GNSS receivers on smartphones can be ambiguous and has concerns when used in field investigations due to internal and external factors. Despite the fact that these factors are well known, the degree of influence of these factors on the accuracy of components of location data provided by smartphones is unexplored. This study aims to statistically assess the influence of three factors (time of the day, landscape characteristics, and ability to track signals of multiple GNSS constellations) on the accuracy of spatial data provided by smartphone GNSS. The horizontal and vertical accuracies of smartphones are within 40 m and 15 m, respectively. The results reveal that the ability to track multi-constellation and landscape properties, respectively, has a significant influence on the horizontal and vertical accuracies of smartphone location information. Further, this study also provides insights to improve the reliability of spatial data collection using smartphones in outdoor environments.
item: Conference-Full-text
A study of underground and surface mining methods in Sri Lanka and its suitability assessment
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Thanujan, T; Brinthan, K; Shivadhahini, S; Subasinghe, MAIIJ; Vettinathan, S; Dharmaratne, PGR; Hemalal, PVA; Chaminda, SP; Jayawardena, CL; Dissanayake, DMDOK; Jayawardena, CL
The demand for minerals is rapidly increasing with industrialization, urbanization, and population growth. Sri Lanka has the potential to penetrate the world market with its endowed rich base of minerals despite its small land area. However, selecting a suitable mining method and its optimum utilization have significant roles in the growth of the local mineral mining industry. The lack of systematic approaches in mining methods is suboptimal for the economic growth of Sri Lanka, which demands immediate investigation and reassessment of contemporary mining practices. Thus, this study aims to critique the major mining practices and evaluate their suitability through characteristics and numerical analysis. This investigation was performed for underground mining methods: cut-and-fill stoping and open-stoping; surface mining methods: open-pit, and open-cast placer mining with reference to Bogala, Kahatagaha, Aruwakkalu, and Pulmoddai, respectively. A detailed study complying with the principles of the grounded theory was conducted through a multimethod approach followed by a thematic and content analysis along with the deductive approach. Moreover, the suitability of these methods was evaluated employing the University of British Columbia method through a numerical approach. This study reveals that the selections of mining methods are appropriate for all four mines, and mining practices are modernized and traditional, complying with site-specific requirements.