Faculty of Engineering
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Publication Embargo Analysis and Quantification of Position Sensor Offset Error in Feedforward Controlled PMSMs(Institute of Electrical and Electronics Engineers, 2022-10-13) Edirisinghe, E. A. Y. G; Rajapaksha, L.T.W; Abeyratne, S. G; Kuruppu, S. SPermanent Magnet Synchronous Machines (PMSM) are popular in transportation electrification applications due to their inherent torque density and ease of control. In torque control applications, field-oriented control (FOC) ensures optimal torque production. However, PMSMs require a rotor position information for FOC, achieved with sensors such as encoder, resolver or linear hall sensor. Feedforward controlled FOC being one key form of PMSM control, the position sensor signal accuracy is paramount. Due to the harsh environments experience by systems in the transportation segment, the position sensor has the potential to misalign from the initially calibrated alignment. This paper focuses on the effects of such position sensor misalignment on feedforward-controlled drives. A novel quantification strategy to detect the failure mode has been presented with analytical details. The methodology is verified through simulation and validated by experimental results. Moreover, a brief analysis-contrasting the effects of position sensor misalignment on feedback and feedforward-controlled drives are presented.Publication Open Access Analysis of Meandering River Morphodynamics Using Satellite Remote Sensing Data—An Application in the Lower Deduru Oya (River), Sri Lanka(MDPI, 2022-07-16) Basnayaka, V; Samarasinghe, J. T; Gunathilake, M. B; Muttil, N; Hettiarachchi, D. C; Abeynayaka, A; Rathnayake, URiver meandering and anabranching have become major problems in many large rivers that carry significant amounts of sediment worldwide. The morphodynamics of these rivers are complex due to the temporal variation of flows. However, the availability of remote sensing data and geographic information systems (GISs) provides the opportunity to analyze the morphological changes in river systems both quantitatively and qualitatively. The present study investigated the temporal changes in the river morphology of the Deduru Oya (river) in Sri Lanka, which is a meandering river. The study covered a period of 32 years (1989 to 2021), using Landsat satellite data and the QGIS platform. Cloud-free Landsat 5 and Landsat 8 satellite images were extracted and processed to extract the river mask. The centerline of the river was generated using the extracted river mask, with the support of semi-automated digitizing software (WebPlotDigitizer). Freely available QGIS was used to investigate the temporal variation of river migration. The results of the study demonstrated that, over the past three decades, both the bend curvatures and the river migration rates of the meandering bends have generally increased with time. In addition, it was found that a higher number of meandering bends could be observed in the lower (most downstream) and the middle parts of the selected river segment. The current analysis indicates that the Deduru Oya has undergone considerable changes in its curvature and migration rates.Publication Open Access Application of GIS Techniques in Identifying Artificial Groundwater Recharging Zones in Arid Regions: A Case Study in Tissamaharama, Sri Lanka(MDPI, 2022-12-10) Kariyawasam, T; Basnayake, V; Wanniarachchi, S; Sarukkalige, R; Rathnayake, UGroundwater resources are severely threatened not only in terms of their quality but also their quantity. The availability of groundwater in arid regions is highly important as it caters to domestic needs, irrigation, and industrial purposes in those areas. With the increasing population and human needs, artificial recharging of groundwater has become an important topic because of rainfall scarcity, high evaporation, and shortage of surface water resources in arid regions. However, this has been given the minimum attention in the context of Sri Lanka. Therefore, the current research was carried out to demarcate suitable sites for the artificial recharging of aquifers with the help of geographic information system (GIS) techniques, in one of the water-scarce regions in Sri Lanka. Tissamaharama District Secretariat Division (DSD) is located in Hambanthota district. This region faces periodic water stress with a low-intensity seasonal rainfall pattern and a lack of surface water sources. Hydrological, geological, and geomorphological parameters such as rainfall, soil type, slope, drainage density, and land use patterns were considered to be the most influential parameters in determining the artificial recharging potential in the study area. The GIS tools were used to carry out a weighted overlay analysis to integrate the effects of each parameter into the potential for artificial groundwater recharge. The result of the study shows that 14.60% of the area in the Tissamaharama DSD has a very good potential for artificial groundwater recharge, while 41.32% has a good potential and 39.03% and 5.05% have poor and very poor potential for artificial groundwater recharge, respectively. The southern part of the DSD and the Yala nature reserve areas are observed to have a higher potential for artificial groundwater recharge than the other areas of Tissamaharama DSD. It is recommended to test the efficiency and effects of groundwater recharge using groundwater models by simulating the effects of groundwater recharge in future studies. Therefore, the results of the current research will be helpful in effectively managing the groundwater resources in the study area.Publication Open Access Appraisal of Satellite Rainfall Products for Malwathu, Deduru, and Kalu River Basins, Sri Lanka(MDPI, 2022-10-20) Perera, H; Senaratne, N; Gunathilake, M. B; Mutill, N; Rathnayake, USatellite Rainfall Products (SRPs) are now in widespread use around the world as a better alternative for scarce observed rain gauge data. Upon proper analysis of the SRPs and observed rainfall data, SRP data can be used in many hydrological applications. This evaluation is very much necessary since, it had been found that their performances vary with different areas of interest. This research looks at the three prominent river basins; Malwathu, Deduru, and Kalu of Sri Lanka and evaluates six selected SRPs, namely, IMERG, TRMM 3B42, TRMM 3B42-RT, PERSIANN, PERSIANNCCS, PERSIANN-CDR against 15+ years of observed rainfall data with the use of several indices. Four Continuous Evaluation Indices (CEI) such as Root Mean Square Error (RMSE), Percentage Bias (PBIAS), Pearson’s Correlation Coefficient (r), and Nash Sutcliffe Efficiency (NSE) were used to evaluate the accuracy of SRPs and four Categorical Indices (CI) namely, Probability of Detection (POD), Critical Success Index (CSI), False Alarm Ratio (FAR) and Proportion Correct (PC) was used to evaluate the detection and prediction accuracy of the SRPs. Then, the Mann–Kendall Test (MK test) was used to identify trends in the datasets and Theil’s and Sens Slope Estimator to quantify the trends observed. The study of categorical indicators yielded varying findings, with TRMM-3B42 performing well in the dry zone and IMERG doing well in the wet zone and intermediate zone of Sri Lanka. Regarding the CIs in the three basins, overall, IMERG was the most reliable. In general, all three basins had similar POD and PC findings. The SRPs, however, underperformed in the dry zone in terms of CSI and FAR. Similar findings were found in the CEI analysis, as IMERG gave top performance across the board for all four CEIs in the three basins. The three basins’ overall weakest performer was PERSIANN-CCS. The trend analysis revealed that there were very few significant trends in the observed data. Even when significant trends were apparent, the SRP projections seldom captured them. TRMM-3B42 RT had the best trend prediction performance. However, Sen’s slope analysis revealed that while the sense of the trend was properly anticipated, the amplitude of the prediction significantly differed from that of the observed data.Publication Open Access The Assessment of Climate Change Impacts and Land-use Changes on Flood Characteristics: The Case Study of the Kelani River Basin, Sri Lanka(MDPI, 2022-10-09) Samarasinghe, J. T; Makumbura, R. K; Wickramarachchi, C; Sirisena, J; Gunathilake, M.B; Muttil, N; Yenn Teo, F; Rathnayake, UUnderstanding the changes in climate and land use/land cover (LULC) over time is important for developing policies for minimizing the socio-economic impacts of riverine floods. The present study evaluates the influence of hydro-climatic factors and anthropogenic practices related to LULC on floods in the Kelani River Basin (KRB) in Sri Lanka. The gauge-based daily precipitation, monthly mean temperature, daily discharges, and water levels at sub-basin/basin outlets, and both surveyed and remotely sensed inundation areas were used for this analysis. Flood characteristics in terms of mean, maximum, and number of peaks were estimated by applying the peak over threshold (POT) method. Nonparametric tests were also used to identify the climatic trends. In addition, LULC maps were generated over the years 1988–2017 using Landsat images. It is observed that the flood intensities and frequencies in the KRB have increased over the years. However, Deraniyagala and Norwood sub-basins have converted to dry due to the decrease in precipitation, whereas Kithulgala, Holombuwa, Glencourse, and Hanwella showed an increase in precipitation. A significant variation in atmospheric temperature was not observed. Furthermore, the LULC has mostly changed from vegetation/barren land to built-up in many parts of the basin. Simple correlation and partial correlation analysis showed that flood frequency and inundation areas have a significant correlation with LULC and hydro-climatic factors, especially precipitation over time. The results of this research will therefore be useful for policy makers and environmental specialists to understand the relationship of flood frequencies with the anthropogenic influences on LULC and climatic factors.Publication Open Access Brain Activity Associated with the Planning Process during the Long-Time Learning of the Tower of Hanoi (ToH) Task: A Pilot Study(MDPI, 2022-10-28) Mitani, K; Rathnayake, N; Rathnayake, U; Linh Dang, T; Hoshino, YPlanning and decision-making are critical managerial functions involving the brain’s executive functions. However, little is known about the effect of cerebral activity during long-time learning while planning and decision-making. This study investigated the impact of planning and decision-making processes in long-time learning, focusing on a cerebral activity before and after learning. The methodology of this study involves the Tower of Hanoi (ToH) to investigate executive functions related to the learning process. Generally, ToH is used to measure baseline performance, learning rate, offline learning (following overnight retention), and transfer. However, this study performs experiments on long-time learning effects for ToH solving. The participants were involved in learning the task over seven weeks. Learning progress was evaluated based on improvement in performance and correlations with the learning curve. All participants showed a significant improvement in planning and decision-making over seven weeks of time duration. Brain activation results from fMRI showed a statistically significant decrease in the activation degree in the dorsolateral prefrontal cortex, parietal lobe, inferior frontal gyrus, and premotor cortex between before and after learning. Our pilot study showed that updating information and shifting issue rules were found in the frontal lobe. Through monitoring performance, we can describe the effect of long-time learning initiated at the frontal lobe and then convert it to a task execution function by analyzing the frontal lobe maps. This process can be observed by comparing the learning curve and the fMRI maps. It was also clear that the degree of activation tends to decrease with the number of tasks, such as through the mid-phase and the end-phase of training. The elucidation of this structure is closely related to decision-making in human behavior, where brain dynamics differ between “thinking and behavior” during complex thinking in the early stages of training and instantaneous “thinking and behavior” after sufficient training. Since this is related to human learning, elucidating these mechanisms will allow the construction of a brain function map model that can be used universally for all training tasks.Publication Open Access CIRCULAR ECONOMY (CE) BASED MATERIAL SELECTION: DEVELOPMENT OF A CE-BASED ‘10R’ EVALUATION FRAMEWORK FOR BUILDING CONSTRUCTION PROJECTS IN SRI LANKA(https://ciobwcs.com, 2022-06-24) Wanaguru, K; Mallawaarachchi, H; Vijerathne, DThe building construction industry is globally identified as one of the major consumers of materials. Thus, the material wastage in building construction projects is very excessive. In the Sri Lankan construction industry, it was identified that the main reason for generating material wastage is the absence of proper material selection criteria. The concept of Circular Economy (CE) has been obtained the world attention in reducing material wastage in the construction industry as it targets zero waste and pollution throughout the lifecycle of materials. Applying CE principles in the material selection not only reduces the wastage of materials but also reduces the use of virgin materials. Hence, this research aimed for developing a CE-based 10R evaluation framework for materials selection in order to reduce the wastage of materials in building construction projects in Sri Lanka. A comprehensive literature review was first conducted to review the concept of CE, CE principles and its importance for reducing material wastage in the construction industry. Deductive approach was chosen as the suitable research approach in this study. Survey method was applied as the suitable research strategy under quantitative phenomenon. A questionnaire survey was conducted with a conveniently selected sample of 58 industry professionals to collect the data. The collected data were analysed by using Weighted Mean Average (WMA) technique. As key findings derived through analysis, the level of importance of each CE principle for selection of materials was determined. Accordingly, the CE-based 10R evaluation framework for material selection was developed as the main implication of this research. Various strategies, such as reusing demolition materials, adopting prefabricated building components, developing plans to on-site recycle and using alternative materials were also proposed to implement the all identified CE principles assuring a successful application of the developed framework.Publication Open Access Comparison of Calibration Approaches of the Soil and Water Assessment Tool (SWAT) Model in a Tropical Watershed(MDPI, 2022-10-22) Makumbura, R. K; Gunathilake, M. B; Samarasinghe, J. T; Confesor, R; Muttil, N; Rathnayak, UHydrologic models are indispensable tools for water resource planning and management. Accurate model predictions are critical for better water resource development and management decisions. Single-site model calibration and calibrating a watershed model at the watershed outlet are commonly adopted strategies. In the present study, for the first time, a multi-site calibration for the Soil and Water Assessment Tool (SWAT) in the Kelani River Basin with a catchment area of about 2340 km2 was carried out. The SWAT model was calibrated at five streamflow gauging stations, Deraniyagala, Kithulgala, Holombuwa, Glencourse, and Hanwella, with drainage areas of 183, 383, 155, 1463, and 1782 km2 , respectively, using three distinct calibration strategies. These strategies were, utilizing (1) data from downstream and (2) data from upstream, both categorized here as single-site calibration, and (3) data from downstream and upstream (multi-site calibration). Considering the performance of the model during the calibration period, which was examined using the statistical indices R 2 and NSE, the model performance at Holombuwa was upgraded from “good” to “very good” with the multi-site calibration technique. Simultaneously, the PBIAS at Hanwella and Kithulgala improved from “unsatisfactory” to “satisfactory” and “satisfactory” to “good” model performance, while the RSR improved from “good” to “very good” model performance at Deraniyagala, indicating the innovative multi-site calibration approach demonstrated a significant improvement in the results. Hence, this study will provide valuable insights for hydrological modelers to determine the most appropriate calibration strategy for their large-scale watersheds, considering the spatial variation of the watershed characteristics, thereby reducing the uncertainty in hydrologic predictions.Publication Open Access Comparison of Instrumented Pile Load Test Results with Finite Element Simulation(World Congress on Civil, Structural, and Environmental Engineering, 2022-04-10) Diyes, G. H. I.; Thilakasiri, H.S.; de Silva, L.I.NDue to the proximity of the bedrock, rock socketed bored and cast in-situ piles are used to support the heavy super structure loads from the high-rise structures transferring to bedrock. In order to design single piles or group of piles, it is very important to know the carrying capacity of the bedrock in terms of skin friction distribution along the pile shaft and the load carried by the pile toe. Such information can be obtained by using the instrumented pile load tests but the instrumented pile load tests are expensive and not always carried out in most of the piling sites in Sri Lanka. In this study, it was aimed to find out the carrying capacity of cast in-situ bored single piles using commonly used finite element software PLAXIS 2D and compare the results with the instrumented pile load test results obtained in the field. Prior to the use of software package based on finite element analysis to find out the carrying capacity of the pile, the accuracy of the model used was verified by the results instrumented pile load test and the nearby borehole test results. Further, the differences and the difficulties of the interpretation of results with their potential reasons were discussed within the study. In the current study, the soil and rock properties were used from the nearby borehole results. It was shown that the best match results with the field instrumented pile load tests for weathered rocks were obtained when the elastic modulus for rock layers were twice the value suggested by Hong Kong geo guidelines (Geo,2006) whereas the best match results with instrumented pile load test results were given when half the value of the Young’s modulus of rock suggested by the Hong Kong geo guidelines (Geo,2006).Publication Open Access Computation of Time of Concentration Based on Two-Dimensional Hydraulic Simulation(MDPI, 2022-10-07) Zolghadr, M; Rafiee, M.R; Esmaeilmanesh, F; Fathi, A; Tripathi, R.P; Rathnayake, U; Gunakala, S. R; Azamathulla, H. M: Time of concentration (TC) is a parameter in runoff estimation, used to study and design different types of projects in watersheds. Any error in TC calculation leads to an inaccurate estimation of the design flow, which can lead to over-sizing or under-sizing of designed facilities that can have great economic and environmental consequences. Therefore, choosing the correct method to estimate TC is of great importance. Due to the diversity of estimation methods in the literature, the obtained TC values are different. This study aims to present a new method to calculate TC, based on its main concept, i.e., the time required for a water parcel to reach its outlet from the farthest hydrological point of a watershed. A two-dimensional hydraulic simulation was used to model the water parcel travel. A watershed was selected as a case study, and its time of concentration was determined by salt solution tracing. The field measurement results were used for calibration of the numerical simulation model. Meanwhile, 31 empirical relations in the literature were reviewed to determine the most accurate ones. Estimated TC values were compared with the measured ones, and the relative error percentage was used to evaluate the accuracy of the result. In the empirical TC methods, the maximum error was above 300%, and the minimum error was 6.7% for the field studied area. The relative errors of hydraulic simulation outputs were between 3 and 27%. The results showed that only three empirical methods, namely Simas and Hawkins, SCSlag, and Yen and Chow, had the least errors respectively equal to 6.7%, 8.660%, and 13.5%, which can be recommended for the studied area and those with similar hydrological characteristics. On the other hand, hydraulic simulation is also introduced as an efficient method to determine TC which can be used in any desired watershed.Publication Embargo The deflectors influence on flow complexity, bed morphology, sediment transport and water quality of urban lotic waters - A laboratory study(wiley, 2022-11-25) Sooriyaarachchi, D. T. A; Gomes, P. I. AIn this laboratory study different combinations of bed (sand, pebble gravel [gravel], and a mix of sand and gravel) and flow (typical and overtopping) were experimented with to investigate the impact of porous deflectors in flow diversity, water quality, and fish performance in prismatic open channels. Deflectors changed the gradually varied flow to a rapidly varied flow, as a sudden change in the water depth was observed at the deflectors, and this change was large for smooth beds. With the presence of gravel, the scouring near the downstream deflector was almost twice that of the sand bed, and with the scouring at its own upstream deflector, irrespective of whether the flow was typical or overtopping. This behavior was a result of sand mobilization due to shear stress and sand mobilization aided gravel transport. The mixed bed showed less gravel movement compared to the gravel-only bed. The percentage of sediment washed out was minor for all bed scenarios, indicating that sediment transport was local. Relative to the sand bed without deflectors (representing a typical urban canal), deflectors resulted in reduced and improved water quality (in terms of sediment load) for sand, and mixed bed, respectively. The fishes found refuge and were comfortable in the pool areas created by deflectors unlike in channels without deflectors where they showed exhaustionPublication Open Access EFFECT OF COVID-19 ON THE SMALL-SCALE CONSTRUCTION COMPANIES: THE CASE OF COLOMBO DISTRICT, SRI LANKA(Ceylon Institute of Builders, 2022-06-26) Gunarathna, N; Namarathna, C. PCOVID-19 is a global pandemic that has wreaked havoc on the lives of many individuals and has had a severe impact on the global economy. During this crisis, small and medium-scale businesses suffer the most and are the least prepared among all companies as per the previous studies done in other parts of the world. The majority of the small-scale construction firms in Sri Lanka act as subcontractors and generate job opportunities for a considerable number of people and are able to create a multiplier effect on the whole economy. However, it was observed that they are more vulnerable to the adverse impact of the pandemic. Thus, the principal goal of this research is to explore possible survival strategies to overcome critical financial issues of small-scale construction companies during the ongoing COVID-19 pandemic in Sri Lanka. A mixedmethod approach was adopted to gather the data for the study. A comprehensive literature review was carried out to identify the impact of COVID-19 on both global and local construction industries. The data for this study was gathered using semi-structured interviews and a comprehensive questionnaire survey with small scale construction company owners and construction industry professionals. The findings highlighted the key financial issues faced by the small-scale construction companies due to the pandemic including delays in client payments, supply chain management issues, frequent price escalation of construction materials, and inability to repay loans. The respondents suggested creating partnerships with financially strong companies, reduction of unwanted expenses, modifying supply chain channels and agreements, and ensuring business continuity plans as the strategies to be used to overcome the financial burden that occurred due to the pandemic.Publication Open Access Erratum to “Using social and economic factors for ranking pavement maintenance and rehabilitation projects(Elsevier, 2022-01) Gunathilaka, S; Amarasingha, NCurrent pavement maintenance and rehabilitation project prioritization in Sri Lanka considers only economic factors while neglecting social, political, and environmental factors. In this study, the Analytic Network Process (ANP), which can be used as a multicriteria decision-making tool, was utilized for the evaluation of three different pavement maintenance and rehabilitation projects in Sri Lanka. Social and economic factors that affected the three projects were considered and the inner and outer dependencies among them were evaluated and weighted. Pairwise comparisons were conducted complemented by interviews of transportation experts from the Road Development Authority (RDA) of Sri Lanka. Given that the RDA’s current method only considers economic factors, our results highlighted differences between the two methods. Therefore, ANP could be recommended for prioritizing pavement maintenance and rehabilitation projects in Sri LankaPublication Open Access Feasibility study for estimating optimal substrate parameters for sustainable green roof in Sri Lanka(Springer Science and Business Media B.V., 2022-12-21) Kader, S. A; Spalevic, V; Dudic, BIn twenty-frst century buildings, green roof systems are envisioned as great solution for improving Environmental sustainability in urban ecosystems and it helps to mitigate various health hazards for humans due to climatic pollution. This study determines the feasibility of using fve domestic organic wastes, including sawdust, wood bark, biochar, coir, and compost, as sustainable substrates for green roofs as compared to classical Sri Lankan base medium (fertiliser+potting mix) in terms of physicochemical and biological parameters associated with growing mediums. Comprehensive methodologies were devised to determine the thermal conductivity and electric conductivity of growing mediums. According to preliminary experimental results, the most suitable composition for green roof substrates comprised 60% organic waste and 40% base medium. Sawdust growing medium exhibited the highest moisture content and minimum density magnitudes. Biochar substrate was the best performing medium with the highest drought resistance and vegetation growth. The wood bark substrate had the highest thermal resistance. Growing mediums based on compost, sawdust, and coir produced the best results in terms of nitrate, phosphate, pH, and electric conductivity (EC) existence. This study provided a standard set of comprehensive comparison methodologies utilising physicochemical and biological properties required for substrate characterization. The fndings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements.Publication Open Access A GIS-Based Comparative Analysis of Frequency Ratio and Statistical Index Models for Flood Susceptibility Mapping in the Upper Krishna Basin, India(MDPI, 2022-11-20) Pawar, U; Suppawimut, W; Muttil, N; Rathnayake, UThe Upper Krishna Basin in Maharashtra (India) is highly vulnerable to floods. This study aimed to generate a flood susceptibility map for the basin using Frequency Ratio and Statistical Index models of flood analysis. The flood hazard inventory map was created by 370 flood locations in the Upper Krishna Basin and plotted using ArcGIS 10.1 software. The 259 flood locations (70%) were selected randomly as training samples for analysis of the flood models, and for validation purposes, the remaining 111 flood locations (30%) were used. Flood susceptibility analyses were performed based on 12 flood conditioning factors. These were elevation, slope, aspect, curvature, Topographic Wetness Index, Stream Power Index, rainfall, distance from the river, stream density, soil types, land use, and distance from the road. The Statistical Index model revealed that 38% of the area of the Upper Krishna Basin is in the high- to very-high-flood-susceptibility class. The precision of the flood susceptibility map was confirmed using the receiver operating characteristic and the area under the curve value method. The area under the curve showed a 66.89% success rate and a 68% prediction rate for the Frequency Ratio model. However, the Statistical Index model provided an 82.85% success rate and 83.23% prediction rate. The comparative analysis of the Frequency Ratio and Statistical Index models revealed that the Statistical Index model was the most suitable for flood susceptibility analysis and mapping flood-prone areas in the Upper Krishna Basin. The results obtained from this research can be helpful in flood disaster mitigation and hazard preparedness in the Upper Krishna Basin.Publication Open Access Green roof substrates—A literature review(frontiersin, 2022-10-03) Kader, S; Chadalavada, S; Jaufer, L; Spalevic, V; Dudic, BGreen roofs are becoming increasingly popular in urban construction due to their wide array of benefits for creating a sustainable ecosystem. Many stakeholders invest in green roofs in the 21st century to enhance the environmental quality and mitigate urban ecological pollution. The substrate layer is the most important and critical component of green roof systems. The objective of the review study is to present the important information regarding the required elements that need to be considered for substrate selection of green roofs by critically reviewing the scientifically published articles. Research findings from past studies relevant to green roofs, vegetation and selective substrate parameters were extensively discussed under different topics related to water retention, drought resistance and related physico-chemical parameters. The generalities in past research articles were presented and special focus was provided on specific research articles those presented novelty regarding green roof substrates. Furthermore, the hotspots in all the considered research articles were commentatively identified and the appropriate solutions were evaluated. The critical review of published research articles indicates that most of the research on green roof substrates was conducted in either controlled laboratories or greenhouses and did not provide much importance to actual field tests. Therefore, these research findings are not sufficient to obtain the realistic field outcomes of the research. Future studies on green roof substrates should need to incorporate field experiments along with classical controlled tests by adhering to standard guidelines for assimilating climatic influences in substrates. Few studies have focused on dry climates, and further research needs to be conducted on dry climates due to their high susceptibility to drought and evapotranspiration. This manuscript would be the first review article that mainly focuses on substrates for green roofs, which is a novel aspect.Publication Open Access Implementation of water–saving agro technologies and irrigation methods in agriculture of Uzbekistan on a large scale as an urgent Issue(Springer Science and Business Media Deutschland GmbH, 2022-10) Rathnayake, U; Chathuranika, I; Khaniya, B; Neupane, K; Rustamjonovich, K. MUsable water resource is limited, even though 71% of world is covered by water. Therefore, enough conficts to the usable water can be found throughout the world. Usable water for irrigation is a top priority, probably it would be seconding only to the drink water supply. However, prioritizing one usage over another is challenging to many stakeholders. Therefore, sustainable water usage is essential to avoid any conficts among the stakeholders; nevertheless, highly challenging in the developing world. Therefore, this paper discusses the water saving irrigation practices and ways to use agriculture around the world, including Uzbekistan. Relying on the ancient irrigation technologies used by ancestors and also modern irrigation methods, diferent irrigation water management technologies are presented to apply for various weather conditions and water availability situations. Suitable irrigation practices are discussed based on the water needs especially the arid countries, such as Uzbekistan. The results of an experiment conducted for hilly areas of Uzbekistan using “mulching” agro-technology is presented along with its suitability for Uzbekistan. Therefore, the expectations of sustainable water usage for irrigation is proposed.Publication Open Access IMPLEMENTING SAFE WORKING CYCLE (SWC) CONCEPT AMIDST THE COVID-19 CRISIS IN SRI LANKA(Ceylon Institute of Builders, 2022-06-26) Rasanjana, H.P; Allis, CThe phenomenon of COVID-19 has introduced critical challenges in the architecture, engineering, and the entire construction industry. A safe Working Cycle is a Japanese concept. It incorporates to enhances the effective implementation of safety management systems, thereby helping to prevent health and safety issues. This research mainly aims at identifying the strategies for overcoming barriers to implementing the Safe Working Cycle (SWC) concept during the COVID-19 pandemics in Sri Lanka. The research study focused more on reducing health-related illnesses caused by COVID-19 than on the other physical safety issues at the construction site. In such a critical health issue, the protection of human resources, an essential part of the construction industry, should be prioritized. The aim of the Study was reached through the sequential mixed method. The semi-structured expert interviews were initially conducted, and after that questionnaire survey was achieved among health and safety officers in construction projects in Sri Lanka. In the semi-structured interviews, data were analyzed using Nvivo thematic analysis software and questionnaire survey; M.S. Excel analyzed the collected data. Following the findings, several potential barriers were arisen to implementing the SWC concept in the Sri Lankan construction industry: including limited Budget allocation, poor safety attitude, limited land space, strict project schedules, and unawareness of workers. Further, this Study also indicated several potential practical strategies to overcome these barriers identified for SWC implementation. Such as; Implementing the COVID-19 bio bubble concept, Organizing regular toolbox meetings, demonstrating sign boards specific to this new concept, arranging separate systematic time slots, buildup a good communication network. The safe Working Cycle (SWC) is not currently practised in Sri Lankan construction culture. However, health and safety professionals are familiar with almost every aspect of the Safe Working Cycle (SWC); therefore, it is possible to put this into practice in the Sri Lankan construction industry. © 2022, Ceylon Institute of BuildersPublication Embargo An Incentivized and Optimized Dynamic Mechanism for Demand Response for Managing Voltage in Distribution Networks(IEEE, 2022-09-05) Rahman, M. M; Arefi, A; Shafiullah, G. M; Hettiwatte, S; Azizivahed, A; Muyeen, S. MThe voltage regulation in distribution networks is one of the major obstacles when increasing the penetration of distributed generators (DGs) such as solar photovoltaics (PV), especially during cloud transients, causing potential stress on network voltage regulations. Residential demand response (DR) is one of the cost-effective solutions for voltage management in distribution networks. However, the main barriers of DR implementation are the complexities of controlling a large number and different types of residential loads, satisfying customers’ preferences and providing them fair incentives while identifying the optimum DR implementation locations and sizing as well as cooperating with the existing network equipment for the effective voltage management in the networks. A holistic and practical approach of DR implementation is missing in the literature. This study proposes a dynamic fair incentive mechanism using a multi-scheme load control algorithm for a large number of DR participants coordinating with the existing network equipment for managing voltage at medium voltage (MV) networks. The multi-scheme load control is comprised of short-interval (10-minute) and long-interval (2-hour) DR schemes. The dynamic incentive rates are optimized based on the energy contribution of DR participating consumers, their influence on the network voltage and total power loss improvement. The proposed method minimizes the DR implementation cost and size, fairly incentivizes the consumers participating in the DR and priorities their consumption preferences while reduces the network power losses and DGs’ reactive power contributions to effectively manage the voltage in the MV networks. An improved hybrid particle swarm optimization algorithm (IHPSO) is proposed for the load controller to provide fast convergence and robust optimization results. The proposed approach is comprehensively tested using the IEEE 33-bus and IEEE 69-bus networks with several scenarios considering a large number of DR participants coordinated with the DGs and on-load tap changer (OLTC) in the networks.Publication Open Access Influence of Crumb Rubber and Coconut Coir on Strength and Durability Characteristics of Interlocking Paving Blocks(MDPI, 2022-07-13) Gamage, S; Palitha, S; Meddage, D. P. P; Mendis, S; Azamathulla, H. M; Rathnayake, UInterlocking Paving Blocks (IPB) are, nowadays, a widely used construction material. As a result of the surge in demand for IPBs, alternative materials have been investigated to be used for IPBs. This study investigated the strength and durability characteristics (compressive strength, split tensile strength, density, water absorption, skid resistance, and abrasion resistance) of IPBs in the presence of (waste materials) crumb rubber (CR) and coconut coir fibers (CCF). Both compressive and split tensile strength increased in the presence of CCF to a certain extent. CR-based IPBs showcased an increase in skid resistance that satisfied both SLS 1425 and BS EN 1338 specifications. Abrasion depths of CR-based and CCF-based samples show a comparable increase in values when the respective fraction (CR or CCF) increases. Therefore, this research fills the knowledge gap, highlighting the importance of incorporating waste materials (CR and CCF) for the IPB industry rather than open dumping.