Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7481
B. Basnayake, U. G. C. R. Madushani
Satellite rainfall estimates (SREs) are high in spatial and temporal resolution and particularly important for regions with sparse raingauges. However, SREs are required to evaluate with gauged rainfall data before applying for hydrological studies. In this research, the accuracy of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks Cloud Classification System (PERSIANN-CCS) product was evaluated at daily, monthly, yearly, and seasonal scale upon the raingauge data of the Kelani River basin of Sri Lanka for the period 2004 to 2010. The performance of the SREs was evaluated using both continuous and categorical verification statistics. PERSIANN-CCS rainfall estimates follow the bi-modal rainfall pattern and showed greater underestimation in South West Monsoon (SWM) season (May-Sep.) and overestimation in InterMonsoon 1 (IM1) period (March-April). PERSIANN-CCS is more capable of recognizing conventional and depressional rains than monsoonal rains. On the other hand, it produces low false alarms in the high rainy season than in the low rainy season. The daily categorical statistics show above average scores (Accuracy>0.69; POD>0.65; FAR<0.34; 0.76>FBias<1.11), however, estimations were with low CC (<0.53) and high bias (<24 & >-64%). Bias corrected PERSIANN-CCS may be a high-resolution rainfall source for flood forecasting applications in the Kelani River basin.
{"title":"Evaluation of PERSIANN-CCS Satellite Derived Rainfall Product with Raingauge Data over Kelani River Basin, Sri Lanka","authors":"B. Basnayake, U. G. C. R. Madushani","doi":"10.4038/engineer.v55i1.7481","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7481","url":null,"abstract":"Satellite rainfall estimates (SREs) are high in spatial and temporal resolution and particularly important for regions with sparse raingauges. However, SREs are required to evaluate with gauged rainfall data before applying for hydrological studies. In this research, the accuracy of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks Cloud Classification System (PERSIANN-CCS) product was evaluated at daily, monthly, yearly, and seasonal scale upon the raingauge data of the Kelani River basin of Sri Lanka for the period 2004 to 2010. The performance of the SREs was evaluated using both continuous and categorical verification statistics. PERSIANN-CCS rainfall estimates follow the bi-modal rainfall pattern and showed greater underestimation in South West Monsoon (SWM) season (May-Sep.) and overestimation in InterMonsoon 1 (IM1) period (March-April). PERSIANN-CCS is more capable of recognizing conventional and depressional rains than monsoonal rains. On the other hand, it produces low false alarms in the high rainy season than in the low rainy season. The daily categorical statistics show above average scores (Accuracy>0.69; POD>0.65; FAR<0.34; 0.76>FBias<1.11), however, estimations were with low CC (<0.53) and high bias (<24 & >-64%). Bias corrected PERSIANN-CCS may be a high-resolution rainfall source for flood forecasting applications in the Kelani River basin.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"254 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73367269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7487
V. Wickramasinghe, D. G. V. C. Diddeniya, K. G. M. Lakmali
{"title":"Gap Acceptance of Crossing Pedestrians at Unprotected Mid-Block Crosswalks in Urban Divided Highways","authors":"V. Wickramasinghe, D. G. V. C. Diddeniya, K. G. M. Lakmali","doi":"10.4038/engineer.v55i1.7487","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7487","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"45 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81622319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7492
A. Abeygunawardane, E. Edirisinghe, A. Karunarathne, H. T. D. W. Ariyarathne, P. Dissanayake, S. Yasawardene
{"title":"Passive Mechanical Characterization of Human Skeletal Muscle Rectus Femoris of Sri Lankan Test Subjects","authors":"A. Abeygunawardane, E. Edirisinghe, A. Karunarathne, H. T. D. W. Ariyarathne, P. Dissanayake, S. Yasawardene","doi":"10.4038/engineer.v55i1.7492","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7492","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"84 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78662482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7489
M. Wickramarachchi, N. Wijesekera
{"title":"Hydrological Modelling with the Tank Model for Water Resource Management of Nilwala River Basin","authors":"M. Wickramarachchi, N. Wijesekera","doi":"10.4038/engineer.v55i1.7489","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7489","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"42 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82331123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7483
B. Basnayake
Morphometric analysis is useful to investigate flood proneness of a river basin. Prioritization of a river basin using relevant morphometric parameters and other causative parameters can be performed using Multi Criteria Decision Analysis (MCDA) method. Nilwala river basin is subjected to flooding every year. The aims of this research were to evaluate the morphometric parameters to understand the hydrological behaviour of the Nilwala river basin and to apply Technique of Order of Preference Similarity to the Ideal Solution (TOPSIS) for prioritizing its sub basins for flood exposure. This study considered morphometric parameters, climatic, geologic, and land use factors as causative factors for flooding. Geographic Information System of Environmental Systems Research Institute (ArcGIS) was used to extract parameters using Digital Elevation Model (DEM) of Shuttle Radar Terrain Mission (SRTM), soil map, and land use map of the river basin. TOPSIS was adopted for ranking the sub basins based on the causative factors. The Nilwala river basin was classified into three relative flood exposure zones as high, moderate, and low. The study indicated that analysis of morphometric parameters provides an intuitive information on sub basin characteristics related to flooding. Results showed that 20%, 54%, and 26% of the basin area have high, moderate, and low flood exposure, respectively. High and moderate flood exposure zones are mainly located along the main river course.
{"title":"Prioritization of Sub-basins of Nilwala River Basin for Flood Exposure using Multi Criteria Decision Analysis","authors":"B. Basnayake","doi":"10.4038/engineer.v55i1.7483","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7483","url":null,"abstract":"Morphometric analysis is useful to investigate flood proneness of a river basin. Prioritization of a river basin using relevant morphometric parameters and other causative parameters can be performed using Multi Criteria Decision Analysis (MCDA) method. Nilwala river basin is subjected to flooding every year. The aims of this research were to evaluate the morphometric parameters to understand the hydrological behaviour of the Nilwala river basin and to apply Technique of Order of Preference Similarity to the Ideal Solution (TOPSIS) for prioritizing its sub basins for flood exposure. This study considered morphometric parameters, climatic, geologic, and land use factors as causative factors for flooding. Geographic Information System of Environmental Systems Research Institute (ArcGIS) was used to extract parameters using Digital Elevation Model (DEM) of Shuttle Radar Terrain Mission (SRTM), soil map, and land use map of the river basin. TOPSIS was adopted for ranking the sub basins based on the causative factors. The Nilwala river basin was classified into three relative flood exposure zones as high, moderate, and low. The study indicated that analysis of morphometric parameters provides an intuitive information on sub basin characteristics related to flooding. Results showed that 20%, 54%, and 26% of the basin area have high, moderate, and low flood exposure, respectively. High and moderate flood exposure zones are mainly located along the main river course.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"117 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76114848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.4038/engineer.v54i4.7475
V. Wickramasinghe, P. Wijesinghe, K. G. M. Lakmali
: Pedestrian start-up time is a very important factor when designing the pedestrian signal phase at a pedestrian crosswalk. Start-up time is divided into two categories as early start-up and delayed star-up time. If a pedestrian starts to move from the curb during the red light, it is termed as early start-up time whereas if the pedestrian starts moving from the curb after the green light, then it is termed as delayed start-up time. Pedestrian crossing time is the summation of the start-up time of the pedestrian and the time required to cross the road. By adding this start-up time into the pedestrian signal phase can reduce the interaction between pedestrians and vehicles, and excess delay at pedestrian crossings. From the initial study, it was observed that start-up time is greatly influenced by the signal configuration. Thus, this research has the intention of assessing the effect of different signal configurations into the pedestrians’ start-up time based on pedestrian characteristics, and thereby, find the best signal configurations with minimum start-up delay. Data was obtained from the video footages from three different pedestrian crossings; (1) Traditional red and green phase, (2) Countdown with waiting time phase, (3) Countdown without waiting time phase. One-way ANOVA statical test was used to evaluate whether there exists any significant deference between these signal configurations. Further, Post-Hoc (Tukey) test was conducted to evaluate which specific signal configuration differs significantly from each other. Finally, a multiple linear regression model was developed by considering start-up time as dependent variable and pedestrian characteristics and signal configurations as independent variables. The model was validated with a R value of 0.75 and pedestrian characteristics such as age, gender, having a bag, and the signal configurations are highly significant to the start-up time in the proposed regression model.
{"title":"Start-Up Time of Crossing Pedestrians with Different Signal Configurations","authors":"V. Wickramasinghe, P. Wijesinghe, K. G. M. Lakmali","doi":"10.4038/engineer.v54i4.7475","DOIUrl":"https://doi.org/10.4038/engineer.v54i4.7475","url":null,"abstract":": Pedestrian start-up time is a very important factor when designing the pedestrian signal phase at a pedestrian crosswalk. Start-up time is divided into two categories as early start-up and delayed star-up time. If a pedestrian starts to move from the curb during the red light, it is termed as early start-up time whereas if the pedestrian starts moving from the curb after the green light, then it is termed as delayed start-up time. Pedestrian crossing time is the summation of the start-up time of the pedestrian and the time required to cross the road. By adding this start-up time into the pedestrian signal phase can reduce the interaction between pedestrians and vehicles, and excess delay at pedestrian crossings. From the initial study, it was observed that start-up time is greatly influenced by the signal configuration. Thus, this research has the intention of assessing the effect of different signal configurations into the pedestrians’ start-up time based on pedestrian characteristics, and thereby, find the best signal configurations with minimum start-up delay. Data was obtained from the video footages from three different pedestrian crossings; (1) Traditional red and green phase, (2) Countdown with waiting time phase, (3) Countdown without waiting time phase. One-way ANOVA statical test was used to evaluate whether there exists any significant deference between these signal configurations. Further, Post-Hoc (Tukey) test was conducted to evaluate which specific signal configuration differs significantly from each other. Finally, a multiple linear regression model was developed by considering start-up time as dependent variable and pedestrian characteristics and signal configurations as independent variables. The model was validated with a R value of 0.75 and pedestrian characteristics such as age, gender, having a bag, and the signal configurations are highly significant to the start-up time in the proposed regression model.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85295346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.4038/engineer.v54i4.7469
B. Kiriparan, J. Jayasinghe, U. I. Dissanayake
: Wind is a random movement of air particles in both time and space, which produces very complicated dynamic loading scenario on flexible structures like tall buildings. Modern tall buildings are becoming more slender, flexible, lightweight and irregular in shape due to revolution of associated technologies. Consequently, analysis of tall buildings considering complicated nature of wind loading and dynamic response of the structural system is an important role in design of tall buildings. Wind tunnel test is the most reliable tool for the estimation of dynamic wind loading on tall buildings. However, due to the cost and time involved, wind design codes are generally used during the preliminary design stage. Thus, understanding the background of dynamic wind loading and procedures adopted in wind design standards to represent the dynamic effects is vital to arrive at an efficient, safe and economical structural system during the preliminary design stage. This paper presents an overview on background of dynamic wind loadings and provisions of four international wind codes frequently referred to in Sri Lanka, British Standard (BS), European Standard (BS EN), Australian Standard (AS/NZS) and Standard of Architectural Institute of Japan (AIJ). Further, the concept of equivalent static load derived based on the “gust-factor” method adopted in most of the international wind design codes is discussed. At the end, a forty-six storied wall-frame structure was used as the numerical example for the explanation of dynamic wind loading and its influence on the structural design.
{"title":"Comparative Study of the Wind Codes: An Application to Forty-Six Storied Wall-Frame Structure","authors":"B. Kiriparan, J. Jayasinghe, U. I. Dissanayake","doi":"10.4038/engineer.v54i4.7469","DOIUrl":"https://doi.org/10.4038/engineer.v54i4.7469","url":null,"abstract":": Wind is a random movement of air particles in both time and space, which produces very complicated dynamic loading scenario on flexible structures like tall buildings. Modern tall buildings are becoming more slender, flexible, lightweight and irregular in shape due to revolution of associated technologies. Consequently, analysis of tall buildings considering complicated nature of wind loading and dynamic response of the structural system is an important role in design of tall buildings. Wind tunnel test is the most reliable tool for the estimation of dynamic wind loading on tall buildings. However, due to the cost and time involved, wind design codes are generally used during the preliminary design stage. Thus, understanding the background of dynamic wind loading and procedures adopted in wind design standards to represent the dynamic effects is vital to arrive at an efficient, safe and economical structural system during the preliminary design stage. This paper presents an overview on background of dynamic wind loadings and provisions of four international wind codes frequently referred to in Sri Lanka, British Standard (BS), European Standard (BS EN), Australian Standard (AS/NZS) and Standard of Architectural Institute of Japan (AIJ). Further, the concept of equivalent static load derived based on the “gust-factor” method adopted in most of the international wind design codes is discussed. At the end, a forty-six storied wall-frame structure was used as the numerical example for the explanation of dynamic wind loading and its influence on the structural design.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"228 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89197911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.4038/engineer.v54i4.7476
Yoshika Alahakoon, A. Kulatunga
The COVID-19 pandemic has created a shift in all our lives, turning in-class traditional educational systems into distance learning systems. Since distance learning is inevitable nowadays, the hands-on experience from in-class, particularly in practical sessions, is lacking. While there is a wide range of tools and technologies to enrich the student learning experience, the application of Augmented Reality (AR) is remarkable. This paper proposes a mobile app assisted with AR technology aimed to support the engineering faculty students to enhance their knowledge regarding the lathe machine and lathe operations during this pandemic period. The application consists of the augmented content of the separate parts of the lathe machine, exploded view and augmented animated content of the operations. The objective of this AR app is to guide the students regarding machineries and operations, and to introduce AR technologies to the local universities as a step of enhancing digital education. The adaptability of the AR app was experienced and verified by 72 students and the responses and feedback revealed their interest towards this educational approach. Conclusively, this study shows the effectiveness and importance of AR application specially for Manufacturing Engineering field during this distance learning period.
{"title":"Application of Augmented Reality for Distance Learning to Teach Manufacturing Engineering during COVID-19 Social Distancing","authors":"Yoshika Alahakoon, A. Kulatunga","doi":"10.4038/engineer.v54i4.7476","DOIUrl":"https://doi.org/10.4038/engineer.v54i4.7476","url":null,"abstract":"The COVID-19 pandemic has created a shift in all our lives, turning in-class traditional educational systems into distance learning systems. Since distance learning is inevitable nowadays, the hands-on experience from in-class, particularly in practical sessions, is lacking. While there is a wide range of tools and technologies to enrich the student learning experience, the application of Augmented Reality (AR) is remarkable. This paper proposes a mobile app assisted with AR technology aimed to support the engineering faculty students to enhance their knowledge regarding the lathe machine and lathe operations during this pandemic period. The application consists of the augmented content of the separate parts of the lathe machine, exploded view and augmented animated content of the operations. The objective of this AR app is to guide the students regarding machineries and operations, and to introduce AR technologies to the local universities as a step of enhancing digital education. The adaptability of the AR app was experienced and verified by 72 students and the responses and feedback revealed their interest towards this educational approach. Conclusively, this study shows the effectiveness and importance of AR application specially for Manufacturing Engineering field during this distance learning period.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"32 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88685524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.4038/engineer.v54i4.7473
P. Fernando, G. D. De Silva
{"title":"Development of a Methodology for Activity Pattern Representation for Individuals in Western Province of Sri Lanka","authors":"P. Fernando, G. D. De Silva","doi":"10.4038/engineer.v54i4.7473","DOIUrl":"https://doi.org/10.4038/engineer.v54i4.7473","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"289 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79443139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.4038/engineer.v54i4.7470
P. S. H. Pallemulla, S. Sooriyaarachchi, C. R. De Silva, C. Gamage
In this experimental research, the effects of gray-level quantization and tiling window size on 22 gray-level co-occurrence matrix features were investigated in the context of automated woven fabric defect detection. A dataset comprising 1426 128×128 images was used, in which defective and the defect-free images were split in a 50:50 ratio. Experiments were carried out with seven quantization levels (LL = 4, 8, 16, 32, 64, 128 and 256) and four window sizes (NN = 8, 16, 32, 64). The features were extracted from each image in the training set for each< LL,NN >combination and thereafter were ranked using the joint mutual information metric. Next, for each < LL,NN > combination, a k-nearest neighbour classifier was trained, first with only the highest-ranking feature and thereafter iteratively by adding features of lower ranks. It was observed that a minimum of nine features were needed to achieve an acceptable (>90%) F1 score for any < LL,NN >combination, except when NN is relatively large. The two features that contribute to improving the F1 score for any < LL,NN >combination were found to be Homogeneity I and Homogeneity II. It was also noted that using an 8×8 window on images with 128 gray levels resulted in a practically usable high F1 score (96.39%) with the least number of features (14).
{"title":"Defect Detection in Woven Fabrics by Analysis of Co-occurrence Texture Features as a Function of Gray-level Quantization and Window Size","authors":"P. S. H. Pallemulla, S. Sooriyaarachchi, C. R. De Silva, C. Gamage","doi":"10.4038/engineer.v54i4.7470","DOIUrl":"https://doi.org/10.4038/engineer.v54i4.7470","url":null,"abstract":"In this experimental research, the effects of gray-level quantization and tiling window size on 22 gray-level co-occurrence matrix features were investigated in the context of automated woven fabric defect detection. A dataset comprising 1426 128×128 images was used, in which defective and the defect-free images were split in a 50:50 ratio. Experiments were carried out with seven quantization levels (LL = 4, 8, 16, 32, 64, 128 and 256) and four window sizes (NN = 8, 16, 32, 64). The features were extracted from each image in the training set for each< LL,NN >combination and thereafter were ranked using the joint mutual information metric. Next, for each < LL,NN > combination, a k-nearest neighbour classifier was trained, first with only the highest-ranking feature and thereafter iteratively by adding features of lower ranks. It was observed that a minimum of nine features were needed to achieve an acceptable (>90%) F1 score for any < LL,NN >combination, except when NN is relatively large. The two features that contribute to improving the F1 score for any < LL,NN >combination were found to be Homogeneity I and Homogeneity II. It was also noted that using an 8×8 window on images with 128 gray levels resulted in a practically usable high F1 score (96.39%) with the least number of features (14).","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"16 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89801550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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