Journal of Advances in Engineering and Technology [JAET]

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The Journal of Advances in Engineering and Technology (JAET) is an international, open access, double blind peer-reviewed journal. It is published by the Faculty of Engineering of Sri Lanka Institute of Information Technology (SLIIT). The JAET aims at fostering research and development work in Engineering and Technology and bringing researchers on to a common platform. Furthermore, JAET will also accept review articles on appropriate subject areas including concept papers of academic opinions, book reviews, etc. for publication therein.

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Open Access
Advancing Audio Surveillance in Simulated Environments: Real-World Soundscapes and Targeted Noise Detection through Enhanced Beamforming Techniques
(SLIIT, Faculty of Engineering, 2025-01) Stroud, S; Jones, K; Edwards, G; Robinson, C; Chandler-Crnigoj, S; Ellis, D
This paper introduces an innovative beamforming approach designed for audio surveillance, executed through a virtual simulation of a real-world environment based at Liverpool John Moores University. Our research is driven by the increasing requirement for sophisticated audio analysis methods to isolate and enhance specific sounds within noisy environments for forensic analysis, for example, in criminal court cases. By leveraging a time-delay beamforming algorithm, our work offers a novel solution to discern and amplify targeted noises amidst complex soundscapes, a challenge commonly encountered in urban surveillance and forensic audio analysis. Our approach's foundation lies in utilising a carefully arranged, robust array of omnidirectional microphones, which are instrumental in capturing a wide range of real-world sound signals. The core of our methodology involves processing captured sounds using the proposed algorithm, followed by evaluating the system's effectiveness in capturing the desired localised audio sources. This paper explores the system's resilience against microphone array degradation, showcasing its robustness in scenarios of partial system functionality. The experiments, grounded in the simulation of real-world acoustic environments, demonstrate the algorithm's adeptness at managing sound reflections and reverberation, critical factors in the realistic replication of urban soundscapes. It also considers the broader implications of our findings, exploring the potential for adopting this technology in various domains beyond law enforcement, including broadcast solutions, advanced audio engineering applications, and animal conservation in the wild. In conclusion, this research showcases a creative approach to audio surveillance and opens the door to numerous applications that can benefit from enhanced methods of audio isolation and analysis. Our findings contribute to the ongoing discourse on developing advanced surveillance technologies, offering insights that could help shape the future of audio processing and analysis.
Open Access
Application of Sentinel-2 Satellite Data to Map Forest Cover in Southeast Sri Lanka through the Random Forest Classifier
(SLIIT, Faculty of Engineering, 2022-09) Gunawansa, T; Perera, K; Apan, A; Hettiarachchi, N
Sentinel-2 satellite data has been used for forest cover monitoring for almost five years. Mapping with Sentinel data will be a cost-effective solution for Sri Lanka, where the lack of updated land cover maps with high spatial resolution is a significant challenge in the land resource management of the country. A study area of about 5,000 km2 located in southeast Sri Lanka was selected for this study. Agricultural lands, forests including Yala national park, and villages with perennial crops make up the region. A Level-2A Sentinel-2 image with less than 10 percent cloud cover was used in the European Space Agency's (ESA) SNAP software version 8.0.0 for image processing and the forest cover of the study area was mapped through the Random Forest classifier (RFC). Normalized Difference Vegetation Index (NDVI) is also calculated as a Sentinel product to support RFC output. For RFC, ground truth data were collected through the reference of Google Earth high-resolution data. The classification accuracy was assessed using the Google Earth image as the reference dataset. Furthermore, RFC results were compared with NVDI greenness values. The classification accuracy was calculated using a confusion matrix (error matrix) through randomly selected 100 sample points. The overall accuracy of the land cover map was 85 percent, with a 96 percent accuracy for forest cover identification. The study found RFC as an effective method to isolate forest cover in Sri Lanka.
Open Access
Attributes of ADR in the Sri Lankan Construction Industry
(SLIIT, Faculty of Engineering, 2022-09-22) Edirisinghe, V; Marsh, D; Borthwick, F; Siriwardena, M; Cotgrave, A
Alternative dispute resolution (ADR) methods were introduced to the construction industry to avoid the negative effects of litigation in relation to the cost, time, and business relationships of a construction project. This study focused on identifying the current ADR practices in the Sri Lankan construction industry and examined the specific attributes of each method to create a more effective process. A qualitative research strategy was carried out with interviews with industry professionals working in the Sri Lankan Construction Industry. Content analysis using NVivo software was used to analyse the data. The key findings revealed that the neutral third party has good knowledge of construction. Despite the differences in each ADR method, disputing parties do not have the confidence in the neutral third party or trust in the process. This study also revealed that the unavailability of these key attributes will finally affect the cost and reputation of the ADR methods. Therefore, the research suggests that to improve the ADR process and its success there should be awareness studies on ADR methods and training for ADR practitioners within the Sri Lankan Construction Industry.
Open Access
A Case Study of Assessing the Accuracy of Secondary Consolidation Prediction Using Qualitative Approach
(SLIIT, Faculty of Engineering, 2024-03) Welikala, C.O.; Vidurapriya, K. V. D.; Thilakasiri, H. S.
Infrastructure constructed, especially over soft organic soil layers, can be subjected to excessive settlement within its life cycle due to the complex behaviour of the soft soil with time. However, with necessary actions prior to construction, the impacts from such soil layers can be mitigated to some extent. The case under consideration is a leisure resort in Matara, a 15-storey hotel resting on a raft foundation near the southern coastal line of Sri Lanka. With time, some cracks have formed within the building, and an investigation was done to identify the cause for the crack formation. It has been determined that cracks have appeared due to the excessive settlement of the subsurface. Furthermore, ground investigation results suggest that a peat layer is beneath the building within a depth of 15-24m. As per the survey report on the settlement of the building, secondary consolidation of the soft soil significantly impacts the excessive settlement. Therefore, three methods were used to predict the secondary consolidation settlement of the peat layer beneath the building. The methods are prediction using empirical correlations, laboratory experiment results that will follow the constant coefficient of secondary consolidation throughout time and the qualitative method, which assumes that the secondary consolidation coefficient varies with time. Based on the above techniques, predictions were made, and results suggest that the qualitative method has a significant accuracy compared to the actual settlements of the building. These observations provide some proof that the coefficient of secondary consolidation varies with time according to the qualitative approach and does not remain constant throughout the lifespan of the building as suggested by conventional methods.
Open Access
Characteristics of Travel Mode Choice of Families with Children Below Five Years Old
(SLIIT, Faculty of Engineering, 2024-03) Zain, A; Amarasingha, N
Travel mode choices for children under five years old have not been fully explored in past research studies The main objectives of this study were to identify travel characteristics of children aged below five years, travel mode choices for them, and investigate the factors affecting their selection. A survey using a questionnaire was conducted with parents in the Western Province of Sri Lanka to collect data. It revealed that private cars as the most frequent vehicle choice followed by public buses. The Multinomial Logistic Regression analysis identified the age of the child, distance, income, type of vehicle owned, and walking time to the nearest public transport station as the main factors that affect the travel mode choice of children under five years old. Also, the habit of securing the child and the child’s familiarity with the use of a car seat when traveling in a private car were identified as factors that affect travel safety. The recommendations were provided to policy makers, parents, and the public in order for children to make safer, comfortable, economical, and sustainable trips.
Open Access
Comparative Lifecycle Analysis of Sri Lankan Non-Conventional Roofing Materials
(SLIIT, Faculty of Engineering, 2023-10) Fernando, W.A.N; Karunaratne, S
Building materials, especially roofing products, play a major role as they are essential for any building construction. Knowledge of the environmental performance of building materials is vital when building life cycle assessment. However, only a few studies have been conducted in Sri Lanka in this regard. The present study focuses on the environmental life cycle assessment of two different nonconventional roofing materials used in Sri Lanka. Acrylonitrile Styrene Acrylate roofing sheets and Calicut-type clay roofing tiles have been selected for the study. In order to measure and calculate environmental impacts of both types of roofing materials, field data was collected quantitatively and noted as per ISO14040 and ISO14044. Using the Cradle-to-Gate LCA technique and OpenLCA software, the environmental impacts as midpoint and endpoint categories were evaluated. As the main output of the study, environmental performance of these two roofing materials were compared, the hotspots of the manufacturing process and the causes were also identified. . Accordingly, the global warming potential of Acrylonitrile Styrene Acrylate roofing sheets and Calicut-type clay roofing tiles is 13.5 kgs of CO2 eq. and 8.95 kgs of CO2 eq. respectively. Further, comparison of the endpoint categories showed the resource depletion was most impactful, indicating 0.814012 points and0.65305 points, respectively for the two roofing material types. Further, kiln firing was identified as the environmental hotspot contributing most to the endpoint and midpoint impact categories for clay roofing tiles, while mixing materials by hot mixer was the hotspot for Acrylonitrile Styrene Acrylate roofing sheets. In addition, the overall results demonstrated how the production process of clay tile influences more than the Acrylonitrile Styrene Acrylate roofing sheet on both the midpoint as well as the endpoint impact categories.
Open Access
Conflict Handling Styles used by Design Team Leaders During Post Contract Stage of Building Construction Projects in Sri Lanka
(SLIIT, Faculty of Engineering, 2024-03) Nuwandhara, R.M.K.K.; De Silva, G.H.S.P.
In comparison to other industries, construction sector encompasses a distinct, complex, and a competitive environment. It enriches the community with improvements when individuals with diverse perspectives, abilities, and degrees of construction expertise collaborate with each other. In this highly competitive multiparty context, conflicts have been labeled as one of the key constraints that prevent the `success of construction projects. Conflict is a fact that everyone must deal with on a regular basis. Construction projects are therefore not an exception. It entails different types of conflicts. To handle these different types of conflicts, construction professionals use different conflict handling styles. Therefore, the aim of this study is to investigate design team leaders’ preference of conflict handling styles and its impact on team spirit of the members of the design team during the post contract stage of building construction projects in Sri Lanka. To collect data, an e-based, closed-ended questionnaire was used incorporating the conflict handling styles introduced in Rahim's Dual Concern theory. The questionnaire was answered by 56 professionals who have the experience of working in the design team during the post contract stage. The study was limited to the building construction projects in Sri Lanka. To analyze the gathered data, descriptive statistics such as mean, percentage, count correlation co-efficient etc. were used. The study has revealed that during the post contract stage, the design team leaders use all five conflict handling styles of Rahim’s Dual concern theory: integrating style, obliging style, dominating style, avoiding style, and compromising style in different frequencies to handle conflicts among design team professionals. The design team professionals often use compromising style and rarely use integrating style, obliging style, dominating style, and avoiding style to handle conflicts among the design team professionals during the post contract stage respectively. Furthermore, the study indicates that these styles bring different levels of impact to the team spirit of design team professionals during the post contract stage of building construction projects in Sri Lanka. The team spirit of design team members is shown to be strongly affected by the compromising style. In contrast, the other four conflict handling styles, integrating style, obligating style, dominating style, and avoiding style, were identified to moderately impact team spirit. Moreover, findings revealed that all these five conflicts handling styles show a strong relationship with the team spirit of design team members during the post-contract stage of building construction projects in Sri Lanka. The research findings may assist construction industry design team leaders and other stakeholders to manage conflicts in a more efficient way and provide an insight to the way to handle conflicts to improve the team spirit of the design team during the post-contract stage of building construction projects in Sri Lanka.
Open Access
Contact Position Estimation in the Event of Simultaneous Multiple Contacts in Vision-based Tactile Sensors
(SLIIT, Faculty of Engineering, 2023-10) Senarath, W. A. T. N; Fernando, S. A. W; Rajakaruna, R. M. T.P
Tactile sensors are used to detect physical contact or pressure. They provide feedback about the physical environment and allow more natural and intuitive interaction with machines. Tactile sensors have many applications in the fields of agriculture, space exploration, health and automotive. Capacitive, resistive, as well as vision (optical) based tactile sensors have been proposed in the literature. This paper proposes a novel approach to solving the problem of estimating the contact locations in the event of simultaneous multiple contacts in vision-based tactile sensors. The relationship between the contact force and the resulting physical deformation of the sensor material of a large-scale tactile sensor was studied with the aid of a custom-built hardware unit. Hardware architecture consists of a custom-designed flat rectangular sensor surface coupled with a mono-vision camera to capture the surface deformation. This method can capture detailed information on the resulting deformation for multiple simultaneous contacts. A software -based deformation estimation algorithm is proposed, where the grid array of marker positions was estimated with a tracking algorithm, an estimation algorithm, and a graphical representation algorithm. Moreover, separate analyses have been carried out to find the best suitable method to observe the deformation of the sensor material. In this study, the approach that was taken to find the contact position and deformation, produced results with an accuracy of more than 97%. Consequently, these results show that this method outperforms existing state-of-the-art techniques in terms of accuracy in the detection of the contact position.
Open Access
Correlation of tensile strength of blended cement concrete with specimen dimensions and aggregate size: A practical test review
(SLIIT, Faculty of Engineering, 2025-02) Amarasinghe, N; Somaratna, N
Test specimen dimensions affect most strength properties of concrete. The existing empirical relationships in this regard are predominantly based on concrete samples made by using Ordinary Portland cement (OPC). An important recent trend in Sri Lanka has been the increasing use of blended cements. This makes it necessary to examine whether the relationships hold for blended cements as well. In this study, split cylinder tensile strength tests were conducted to determine whether the specimen size and the tensile strength of concrete prepared using a blended cement (Portland Composite Cement (PCC)) display relationships similar to OPC. Tests were conducted on specimens using two cement types – OPC and PCC - and three concrete mix ratios and a range of specimen dimensions to study the effect of the specimen length (L), diameter (D), and aggregate size (a) on the split cylinder tensile strength (T). The data was examined using dimensional analysis based on Buckingham's π theorem. A slight increasing trend was observed in the ratio of split cylinder tensile strength to mean a compressive strength (T/fc,mean) with an increasing L/D ratio. As for the ratio of the aggregate size to the specimen diameter (a/D), the analysis showed an increasing trend in T/fc,mean values with an increasing a/D ratio, indicating a significant correlation between T/fc,mean and a/D. A nonlinear regression analysis was used in an attempt to determine a functional relationship among the non-dimensional parameters T/fc,mean, L/D, and a/D. But the differences in the derived relationships for different concrete mixes were too large for reaching a common relationship. Perhaps this was due to the small number of data points available. It was seen that relationships established for OPC may hold true for PCC too. However, the data used was limited in range and more comprehensive further tests should be conducted to confirm these findings.
Open Access
Data Science to Determine Mechanical Properties of Low Carbon Steel During In-Process Inspections
(SLIIT, Faculty of Engineering, 2023-03-02) Alahapperuma, K. G.; Suraweera, D. D. D.; Nandhakumar, N.
Carbon steel is a widely used category of engineering metal, mainly due to its attractive mechanical and fabrication properties and low cost. The chemical composition, physical parameters, and mechanical properties of carbon steel are maintained as per the specified standards, and local steel should be complied with Sri Lankan Standard 375: 2009. Generally, the chemical composition is tested during melt stages, and mechanical properties are tested for finished products. Since it is necessary to ensure products comply with the standard, mechanical properties are tested during in-process inspections as well. When the results are not within the acceptable range, a considerable amount of production has to be rejected, causing a loss to the manufacturers. If the results of the in-process inspection are instant, it will help make suitable adjustments to process conditions and thereby prevent rejection of products, while reducing quality assurance costs, as well. Therefore, the objective of this study is to predict tensile properties with chemical composition, as input variables, to be used for in-process inspections. Forty mechanical test reports were collected from a steel manufacturing factory for 12 mm diameter, thermo-mechanically treated (TMT) steel bars. Each test report is of 15 samples from the respective batch, and consists of corresponding chemical composition and physical parameters. Multiple linear regression analysis was applied to each batch, using Statistical Package for the Social Sciences (SPSS) software, to predict yield strength (YS), ultimate tensile strength (UTS), elongation at break (EB) with carbon equivalent value (CEQ) and percentage of Sulphur as inputs. Relationships between variables were not significant, even though those relationships can be used to predict tensile properties. The predictions may not be reliable, due to the limited conditions of the study and assumptions made. It is therefore recommended to apply multivariate regression analysis or Artificial Neural Network (ANN) techniques, with other chemical elements, process temperature and water flow rate etc. also as input variables.
Open Access
Design and Dynamic Modelling of Knee Exoskeleton for Disabled People through ADAMS-Simulink Co-simulation
(SLIIT, Faculty of Engineering, 2022-09-22) Ranaweera, J. P; Perera, M
This paper is written to outline the progress and findings of an undergraduate research project aimed at the designing and modelling of an exoskeleton design of the knee joint for rehabilitation and gait support. It focuses on the rehabilitation potential of the proposed exoskeleton design on patients with Hemiplegia and Monoplegia conditions with the objective of seeking a feasible, simple means of joint actuation to reduce the complexity of the design. Exoskeleton designs are able to provide rehabilitation and improve the overall quality of life of disabled people globally. However, a common issue found almost everywhere is the costly nature of the exoskeletons that are available in the market now as they are exclusive devices, which makes them inaccessible and impractical to the general public, especially in developing countries. Initially, the paper focuses on the review of relevant literature and previous research and evaluating the designs that have been developed as of now. A thorough analysis of the work done by previous researchers and companies was conducted to gather data on the underlying engineering principles and techniques used for the exoskeleton development as well as any limitations or restrictions to the process. Conceptual designing of the possible solutions was developed using the understanding and knowledge gathered during the literature review. The selection of the best solution was based on the analysis of the pros and cons of all the solutions. The chosen design, utilising a 4-bar mechanism, was then modelled using SolidWorks software to provide a clear visualisation of the system. The kinematic and dynamic analysis of the mechanism was evaluated to analyse the possibility of using the proposed exoskeleton design by replicating the model in ADAMS multibody software. The dynamic analysis was conducted by using the co-simulation platform between ADAMS and Simulink to enable the addition and control of feedback loops within the system. The results of the analysis show that the design can achieve the required motions of the human gait cycle, especially during the swing phase of the gait cycle. The analysis of the actuation torques and reaction forces on the human body showed that an acceptable torque range was possible during the swing phase of the gait cycle.
Open Access
Developing a Rubber based Nanocomposite
(SLIIT, Faculty of Engineering, 2022-09-22) Sadique, M. I. F
Polymer compounds such as Natural Rubber (NR), which consists of compounds such as isoprene, are capable of being processed for the manufacture of a range of rubber based products for a large variety of applications. The properties of a natural rubber compound are susceptible to enhancements in their properties through the incorporation of nanofillers into its matrix. This study addresses the preparation of a natural rubber based nanocomposite that utilizes graphene as a nanofiller for the facilitation of the required enhancement in the rubber compounds properties. The nanocomposite specimens used in the study were prepared by means of acid-coagulation. The acid-coagulation formulation utilized was adapted from methodologies employed in commercial applications. The enhancement in the rubber properties due to the incorporation of the nanofiller was validated by means of mechanical testing. Prior to the testing, the applicable standard for tensile property testing was identified to be ASTM D412. Through the acclaimed standard, a mould to facilitate the preparation of the required specimens was 3D printed from PETG. The primary aim of the study was to determine the effect of large concentrations of graphene (beyond 2.5wt %).The results from the mechanical testing of the acidcoagulated samples exhibited enhancements in the elongation at break and tensile strength between unfilled NR and the graphene filled NR nanocomposite. With the incorporation of 5wt% of graphene, the elongation at break of the rubber increased to 687%, showing a 25% increase. The tensile strength of the rubber increased to 4.07 MPa, showing an enhancement of 102% in comparison to the pristine rubber compound.
Open Access
Development of a Simplified Method of Designing Pervious Concrete Mixes using chip aggregate
(SLIIT, Faculty of Engineering, 2023-10) Fernando, B. J. S.; Naanayakkara, D.
Pervious concrete can be referred to a sustainable paving material which reduces urban runoff, heat-island effect and improves the ground water quality. Due to the lack of awareness and the unavailability of a simplified design method, the applications are limited in the local context. In this research study, a new method of preparing pervious concrete mixes using commercially available chip aggregate together with coarse aggregate was developed. Five volume based binary combinations were prepared with varying coarse aggregate and chip aggregate proportions. A simple mix design method which is based on the porosity of the pervious concrete was used to determine the required cement paste content. For each aggregate combination, cement paste contents were calculated for four different design porosities. Overall, twenty pervious concrete mixes were prepared and test specimens for compressive strength, bending strength and permeability tests were conducted. Based on the test results, relationships between aggregate combination, compressive strength, permeability, and cement paste content were identified and a simplified graphical method of designing pervious concrete mixes to achieve required strength and permeability characteristics was introduced. Further, the addition of chip aggregate enhanced the strength characteristics while retaining adequate permeability.
Open Access
Efficient Ventilation Configurations for an Isolation Ward in View of Reducing the Potential Contamination of Its Occupants
(SLIIT, Faculty of Engineering, 2023-03-02) Durage, H; Attalage, R; Bandara, R.M.P.S.
The rise of respiratory infections, such as the SARS epidemic in 2003, and the H1N1 influenza epidemic in 2011, highlighted the importance of efficient ventilation in healthcare facilities. The novel SARS -Cov-2 disease has sparked many concerns over the ventilation performance of multi-bed isolation wards and their ability to suppress airborne infectious contamination. The study is primarily based on suggesting ventilation improvements for a locally acquired multi-bed intensive care isolation unit. The study via ANSYS -fluent incorporates a k-𝜀 turbulent model that is used to analyze exhaled CO2 particle tracks of 4 human models. Three ventilation strategies, namely, Displacement, Stratum, and Curtain -Air-jet are initially considered and evaluated based on two indoor air quality indices (IAQs), namely, air change efficiency and contaminant removal effectiveness. Stratum ventilation comfortably exhibits unidirectional flow characteristics with an air change efficiency of 0.946, which was obtained through ANSYS -CFX while each suggested configuration is capable of achieving a contaminant removal effectiveness value greater than 1 which depicts that the contamination source is not in a perfect mixing zone. Results provided inconclusive evidence to draw correlations between the two IAQ indices and thus it is confirmed that these indices solely depend on the type of ventilation strategy. Contaminant concentration on health care worker breathing plane and exhaled particle tracking for 4 minutes in each analyzed configuration revealed that both Stratum and Curtain air-jet models improve the escaped particle efficiency by 25% and 29% respectively compared to the base model. These models are further compared against reference values specified by guidelines to evaluate their suitability for real-world operation.
Open Access
Enhancing Load Frequency Control in Interconnected Power Systems with Zone-Specific Fuzzy Controllers: Principles and Methods
(SLIIT Faculty of Engineering, 2025-02) Jahangiri, S; Jones, K.O
This work focuses on load frequency control in interconnected power systems, a critical aspect of modern power grid operations. However, sudden load disturbances and generator outages can lead to transient oscillations between control areas, posing challenges to frequency control. The aim of the work was to investigate and enhance load frequency control behaviour, considering dynamic load changes and uncertainties. Fuzzy Logic Controllers optimized with Particle Swarm Optimization were applied to improve control robustness. The Particle Swarm Optimisation algorithm was used to tune the scaling factors and parameters of the fuzzy controllers to optimize their performance. The methods were tested on a standard four-area interconnected power system model equipped with load frequency control blocks, reheaters, governors, rate constraints, and thermal components. Different disturbance scenarios including parameter fluctuations and load changes were evaluated. The Fuzzy Logic Controllers demonstrate resilient response across scenarios without needing extensive tuning. Particle Swarm Optimization improves robustness through systematic exploration for constraint-based nonlinear optimization. Tuning fuzzy controllers with bio-inspired algorithms enhances efficiency in addressing complex grid conditions. The results provide insights into designing more secure and resilient grid controls, contributing to power system stability research.
Open Access
Evaluating the Effectiveness of Speed Humps Related to Speed Profile and Noise Profile
(SLIIT Faculty of Engineering, 2023-03-02) Gamlath, K.G.D; Amarasingha, N; Wickramasinghe, V
Speed humps are an effective traffic calming measure to improve the safety of road users. On the other hand, speed humps have certain drawbacks, such as increasing emergency response time, causing damage to cars, and high noise levels due to excessive traffic. These impacts further vary with different hump profiles. Thus, the primary objective of this research is to investigate how the geometric profile of speed humps affects vehicle speed and noise level. The secondary objective is to find the Level of Service in the presence and absence of a speed hump by using VISSIM microsimulation. In this study, Lake Drive Road, Nawala, was selected with four different speed hump profiles. The Sound Meter smartphone application was used for noise monitoring. A drone camera footage was utilized to capture vehicle flows while speed trajectories of each vehicle were developed using tracking software. The developed speed profiles were used for the simulation purpose. Then, a Multiple Linear Regression (MLR) model was developed and validated to predict the hump height for the desired speed reduction and desired noise level for each selected four-vehicle category. Further, the average noise levels were found to be higher than the Central Environmental Authority's permissible noise level, and it increases with the height of the hump. It was also observed that as the height of the hump increases, vehicle speed decreases. The largest speed reduction, 42.13 %, was observed in passenger cars, while the lowest speed reduction, 23.5 %, was observed in motorcycles. Therefore, speed analysis findings reveal that passenger cars have a significant speed reduction when compared to other categories. However, the average speed reduction for all vehicles was identified as 33.85 %, and VISSIM simulations revealed that the average Level of Service (LOS) drops to LOS C from LOS A due to the presence of the speed hump.
Open Access
Evaluation of Mechanical Characteristics of Rice-Husk-Bricks
(SLIIT, Faculty of Engineering, 2023-10) Tilakasena, R.S; Tharmarajah, G
Construction activities and materials extraction are major contributors to environmental pollution. To address this issue, the utilization of bio-based materials presents a promising sustainable alternative for the construction industry. Bio-based materials encompass a broad category of organic matter that can be either synthesized or naturally derived. One such noteworthy bio-based material is rice husk, which exhibits pozzolanic properties. Abundantly available as an agricultural waste product, rice husk holds potential as a viable substitute in construction processes. This study is dedicated to investigating the feasibility of replacing fine aggregates, traditionally comprised of sand, in cement blocks with untreated rice husk on a volumetric basis. In contrast to being used merely as an additive, this research delves into the possibility of substantially replacing sand with a higher proportion of rice husk, ranging from 20% to 80%, in the composition of cement blocks. The findings of this study reveal that up to 40% of the sand content in cement blocks can be effectively replaced with untreated rice husk while still meeting the requisite strength standards for non-load bearing blocks. Moreover, this study demonstrates an additional advantage in terms of weight reduction. Substituting sand with rice husk leads to a remarkable 30% reduction in the overall weight of the blocks. These results underscore the potential benefits of integrating rice husk into construction materials as an environmentally friendly and weight-efficient alternative.
Open Access
Experimental Identification of Alkali-Aggregate Reaction in Concrete
(SLIIT, Faculty of Engineering, 2023-03-02) Baddeliyanaralalage Don, R
Several advanced and time-consuming methodologies have been developed to detect Alkali-Silica Reaction (ASR) in suspected structures. The main objective of this research study was to identify a reliable experimental procedure for detecting ASR in existing concrete. A simple staining solution is used here to detect ASR in concrete specimens. The staining reagent employed here is Sodium Cobaltinitrite, which is used in the Los Alamos staining method to detect ASR. Sodium Cobaltinitrite can identify potassium-rich ASR gel by staining it yellow for rapid field screening purposes. Reactive and control concrete specimens were cast to get some experience with this test and to verify whether this test can be used in a suspected concrete structure. Waste white soda-lime glass aggregate was used to cast reactive concrete specimens, whereas natural coarse aggregates were used to cast non-reactive concrete specimens. Testing was carried out in two batches. Each batch consisted of six reactive and six control concrete specimens which were cured in the above-mentioned solutions. The first batch was examined after 44-days and the second batch was tested after 60-days of casting. Results of this test showed that reactive concrete specimens cast using glass displayed yellow stains as expected, demonstrating the presence of potassium-rich ASR gel on the concrete surface. Employing NaOH as a curing medium had accelerated ASR. There is a limitation in the method when utilizing KOH as a curing agent. It is concluded that Sodium Cobaltinitrite can be used as a method for rapid identification of ASR in the preliminary stages of experimental identification of the alkali-aggregate reaction in an existing concrete structure.
Open Access
Fabrication, Characterization, and Gas Sensing Properties of Different Semiconductor Metal Oxide Nanostructures for LPG Detection: A Comparative Study
(SLIIT, Faculty of Engineering, 2025-01) Bandara, A.H.M.N.N.; Senadeera, G.K.R.; Bandara, K.N.D.; Perera, V.P.S.
The research explores how the structural, morphological, and electrical properties of nanostructured semiconductor metal oxides (SMOs), including Cu2O, ZnO, TiO2, and reduced graphene oxide (rGO), synthesized via electrochemical deposition and doctor blading techniques, influence their effectiveness in sensing liquid petroleum gas (LPG). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were used to assess the chemical composition and structure. Cu2O, ZnO, and TiO2 were found to exhibit significant polycrystalline structures, with increasing average crystallite sizes of approximately 42.8 nm, 70.1 nm, and 87.78 nm, respectively. The dominant (111) Cu2O phase displayed a homogeneous cuboid morphology. rGO exhibited a singleplane (002) microstructure with a crumpled paper texture and an average crystallite size of ~85.3 nm, indicating a successful hydrothermal reduction of graphene oxide (GO). UV-vis absorption spectra in the range of 200 – 800 nm revealed the presence of different energy bands in ZnO, TiO2, and rGO, alongside their major band energies of 3.2 eV, 3.3 eV, and 1.9 eV. Cu2O thin films, with the lowest band energy gap of 2.5 eV, exhibited high photocatalytic activity, potentially enhancing chemical reaction rates during gas sensing under light exposure. Additionally, alternating current (AC) impedance spectra of SMO indicated increased film conductivities with positive bias voltages. ZnO films showed the most significant gas response (~27%) for LPG sensing at 70 ℃, with response and recovery times of less than 20 seconds. A stable and considerably high LPG sensitivity of ~11% was discovered with Cu2O. This finding underscores the significance of its relatively small grain size in influencing its sensitivity to LPG.
Open Access
Factors Affecting Red-Light Running of Pedestrians at Signalized Intersections
(SLIIT, Faculty of Engineering, 2022-09-22) Herath, C; Amarasingha, N
Hundreds of pedestrians have died and many have been injured in the past decades as a result of Red Light Running (RLR) infractions. According to the United States Department of Transportation, 846 pedestrians have died and 143,000 have been injured in 2019 due to RLR violations. The majority of previous studies have focused on pedestrian behavior at an intersection, whereas only a few have looked into pedestrian RLR violations. The main objectives of this research are to find the pedestrians’ RLR rate in Sri Lanka and to find ways to reduce the RLR rate of pedestrians at the signalized crossing. Video observation surveys were conducted to collect data at three signalized intersections within Kandy city limits during weekdays for two hours per site. Pedestrian demographic variables such as gender and age; crossing characteristics such as crossing type, direction, crossing speed etc; and site characteristics such as crossing length, pedestrian green time, etc. were recorded. Chi-square and binary logistic regression tests were done. Results showed that out of 178 females, 130 had compliance with signal phases and out of 386 males, only 215 had compliance with RLR of a pedestrian. Furthermore, other independent variables such as age, crossing type, direction etc. were also associated with compliance RLR of pedestrians under Chi-square results. Based on the results of binary logistic regression, the variables such as gender, crossing type, number of traffic lanes, and pedestrian speed are significant when decreasing the log of probability -0.658, -3.040, -1.022 and -2.556 of compliance for RLR respectively. Variables that crosswalk utilization are also significant when increasing the log of probability of RLR 1.406 of compliance for RLR. The results would help develop safer pedestrian infrastructures and engineering countermeasures as well as assist the researchers and practitioners in better understanding pedestrian crossing behavior at signalized intersections.