Research Publications

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item: Conference-Abstract
1 Watt, quasi-cw, diffraction limited, semiconductor double tapered laser oscillator
(Engineering Research Unit, Faculty of Engiennring, University of Moratuwa, 1996-05-31) Dayawansa, IJ
item: Article-Abstract
1/8 Factorial study of metal effects on acid neutralization by cement
Stegemann, J; Perera, ASR; Cheeseman, C; Buenfeld, N;
The acid neutralization capacity of a cement/waste product is important because the integrity of the monolithic matrix and contaminant precipitation are dependent on the maintenance of alkaline conditions. A 1/8 fractional factorial experiment was used to selectively examine the main effects of seven pure metal compounds on strength development and acid neutralization capacity of portland cement paste and to obtain information regarding interactions between the compounds. The hydration products in a portland cement paste appear as plateaus in its titration curve. Metal contaminants were found to affect the pH and acid neutralization capacities of these plateaus, suggesting that they change the hydration products. Cr(NO3)3 and ZnCl2, which exhibited individual effects and also interacted, caused the predominant effects. Comparison between predictions by a simple empirical linear model based on these contaminants and acid neutralization capacity of a real solidified metal plating waste showed that additional factors play an important role in real wastes.
item: Conference-Full-text
A 12v dc/230v ac inverter/charger with advanced Protection features
(Engineering Research Unit, Faculty of Engiennring, University of Moratuwa, 1997-11) Ranaweera, A; Seneviratne, BKCC; Kalyanapala, M; Hettiarachchci, P
The inverter can be used as a source of ac power in the absence of grid power. The battery can also be charged by alternative sources of energy if grid power is not available at all. The unit described works as a batter}' charger when the ac mains power is available and automatically starts working as an inverter when the mains power fails. Regulation of the square wave output voltage is achieved by variation of the pulse width of the waveform. A manual switch is also provided to boost the voltage at higher loads. Protection is provided against overloading of the inverter as well as against improper or incomplete connections during charging, thereby protecting the user as well as the unit. The charging current of the battery as well as the voltage level of the battery are indicated on the front panel of the unit. The unit has worked satisfactorily on many types of loads regardless of the high harmonic content of the square wave output voltage.
item: Conference-Full-text
169 Invisible Architecture; Integrating Subterranean Brussels in Active Neighbourhood Revitalization
(2015-10-02) Dissanayake, A
Brussels is a city with immense potentials and opportunities. Being at the heart of Europe, it is coherently connected with rest of the world both physically and figuratively. However, these opportunities and connections constantly attract people from around the world; giving way to a heterogenic society of diverse ethnicities and cultures. This heterogenic society creates a strong tension in some quarters of Brussels – especially when there is a prominent arrival magnet as with the case of neighbourhood Fountains with Brussels south railway station in close proximity. As with any infrastructure project, the proposed metro and tram station of Lemonier, is a potential for not only the neighbourhood of Fountains but also for entire metropolis of Brussels. The proposed MetCom program incorporating the Brussels underground gives these commonly mono-functional mobility infrastructure projects a new meaning; transforming them into effective urban public spaces. Introduction of this proposed novel logistic system for urban freight transportation allows new possibilities for the use of existing unused space within the metro stations as well as in the adjoining gray buildings. The project not only helps revitalize the neighbourhood by introducing a new economy but also encourages better interaction of the heterogenic society by providing a place for activity. The project however does not create an architectural object; on the contrary, it creates an invisible architecture
item: Conference-Full-text
1st ICBR 2018 [Pre-text]
item: Conference-Full-text
1st International Conference on Electrical Engineering 2016 (Pre Text)
(Institute of Electrical and Electronics Engineers, Inc., 2016-12) Rajapakse, A; Prasad, WD
item: Conference-Full-text
2016 Moratuwa Engineering Research Conference (MERCon) [Pre Text}
(IEEE, 2016)
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2018 Moratuwa Engineering Research Conference (MERCon) [Pre Text]
(IEEE, 2018)
item: Conference-Full-text
2nd Annual Conference on Minerals for a Better Future - A Multidisciplinary Approach [Pre Text]
(Department of Earth Resources Engineering, 2007-11) Karunaratne, S
item: Conference-Full-text
The 2nd International Conference on Electrical Engineering 2018 (Pre Text)
(Institute of Electrical and Electronics Engineers, Inc., 2018) Samarasinghe, R; Abeygunawardana, S
item: Conference-Full-text
2nd International Conference on Information Technology Research 2017 (Pre Text)
(Information Technology Research Unit, Faculty of Information Technology, University of Moratuwa, Sri Lanka, 2017-12) Sudantha, BH
item: Conference-Abstract
3+2 versus 5 : A comparison of the structure of architectural education with reference to course changes at University of Moratuwa
Chandrasekara, DP
The architectural education system at University of Moratuwa (UOM) was changed to a direct 05 year Bachelor of Architecture degree from the 2003 new entrants. Prior to that, the format of the architectural education at UOM was a 03 year B.Sc . (Built Environment) degree and a 02 year M.Sc.(Architecture) postgraduate degree with a minimum of 1 year gaining in between. The structural change of the duration of the course was combined with other major revisions such as the "semesters" and "modules" replacing the "terms" and "subjects" of the old system respectively. The contents of the courses were also changed with the introduction of new areas of studies and elective modules The studio work of architectural design was the forte of both systems. The old system had yearend examinations for theory subjects. The new B.Arch . opted for semester- end examination. The main advantage in the new was that there were lesser possibilities of missing the batch by students due to poor performances in the theory modules. The objectives of this study is to compare the effectiveness of the two systems of education from the perspective of the students. A sample of 30 students; 15 from the last M.Sc. batch and 15 students from the first two batches of B.Arch. students wgfe selected on a random basis. All of them have now completed the part three examination of the Sri Lanka Institute of Architects and are chartered architects. The respondents were divided into two categories "Good students" and "Average Students" based on their performances at UOM. The findings of the study shows that 80% of the "good students" who had followed the B.Arch. programme opt for the same course given a chance to study architecture agaWr 100% of the "average students" select B.Sc. + M.Sc. as their preferred system to study architecture. r " Around 82% of the former B.Arch. students who selected B.Sc + M.Sc path stated that the main reason for the selection is that it gives a postgraduate qualification in addition to the 3 year bachelor degree. Those who selected old system stated that shorter duration and recognition to undergraduate degree as important factors which influenced their decision.
item: Article-Full-text
A 3-D coupled Smoothed Particle Hydrodynamics and Coarse-Grained model to simulate drying mechanisms of small cell aggregates
(Elsevier, 2019) Rathnayaka, CM; Karunasena, HCP; Senadeera, W; Polwaththe-Gallage, HN; Gu, YT
Recently, meshfree-based computational modelling approaches have become popular in modelling biological phenomena due to their superior ability to simulate large deforma- tions, multiphase phenomena and complex physics compared to the conventional grid- based methods. In this article, small plant cell aggregates were simulated using a three di- mensional (3-D) Smoothed Particle Hydrodynamics (SPH) and Coarse-Grained (CG) coupled computational approach to predict the morphological behaviour during drying. The model predictions of these cell aggregate models have been compared qualitatively and quantita- tively through comparisons with experimental findings. The results show that the shrink- age and wrinkling behaviour of cell cluster models are in fairly good agreement with real cellular structures. The agreement between the cell aggregate model predictions and the experimental findings are closer in the high and medium moisture content values ( X / X 0 ≥0.3), than highly dried stages ( X / X 0 < 0.3). Further, optimisation and sensitivity studies have been conducted on model parameters such as particle resolution, smoothing length, mass transfer characteristics and wall forces. Overall, the 3-D nature of this model allows it to predict real 3-D morphological changes more realistically compared to the previous meshfree based 2-D cellular drying models. The proposed 3-D modelling approach has a higher potential to be used to model larger plant tissues with complicated physical and mechanical interactions as well as their multiscale interactions.
item: Article-Full-text
A 3-D sparse FIR frustum filter for enhancing broadband plane waves
(IEEE, 2019) Wijesekara, RT; Edussooriya, CUS; Bruton, LT; Agathoklis, P
A 3-D FIR frustum filter having sparse coefficients is proposed for enhancing broadband plane waves received by uniform aperture arrays. Motivated by the design technique of 1-D interpolated FIR filters, the proposed filter is realized by cascading a spatially-upsampled 3-D FIR prototype filter having a frustum-shaped passband and a 3-D FIR masking filter having a parallelepiped passband. Sparsity of the filter coefficients is achieved through the spatial upsampling of the coefficients of the prototype filter and by hard-thresholding the coefficients of both prototype and masking filters. The proposed 3-D FIR frustum filter saves 39:5% multiplications and 66:6% additions compared to the state-of-the-art 3-D FIR frustum filters without degrading the performance in enhancing broadband plane waves.
item: Conference-Abstract
3D Environmental force : position impedance variation for different motion parameters
Ruwanthika, RMM; Harsha, AM; Abeykoon, S
The skill preservation of an expert has been a serious problem for countries with aging population because decrease of the number of successors. The concepts of haptic database and force sensor recorder which have been developed recently suggests solutions of using third multimedia type of haptic communication. Haptic information is a bilateral information of the law of action and reaction. The reaction from real world includes not only position and force information but also environmental impedance. In this paper, the behavior of environmental impedance has been studied with the changes of the different motion parameters like applied force, velocity, position and depth on the object 3D space. This idea is exemplified using a rubber balloon and a rubber sponge which is often modeled using simple linear equations. The experimental results show the importance of considering motion parameters when abstracting haptic information for a haptic database. Nonlinear impedance variations against the motion parameters suggest the necessity of adopting complex haptic abstraction techniques.
item: Conference-Full-text
3D Environmental Force:Position Impedance Variation for Different Motion Parameters
(2015-08-03) Ruwanthika, RMM; Harsha, AM; Abeykoon, AMHS
The skill preservation of an expert has been a serious problem for countries with aging population because decrease of the number of successors. The concepts of haptic database and force sensor recorder which have been developed recently suggests solutions of using third multimedia type of haptic communication. Haptic information is a bilateral information of the law of action and reaction. The reaction from real world includes not only position and force information but also environmental impedance. In this paper, the behavior of environmental impedance has been studied with the changes of the different motion parameters like applied force, velocity, position and depth on the object 3D space. This idea is exemplified using a rubber balloon and a rubber sponge which is often modeled using simple linear equations. The experimental results show the importance of considering motion parameters when abstracting haptic information for a haptic database. Nonlinear impedance variations against the motion parameters suggest the necessity of adopting complex haptic abstraction techniques.
item: Conference-Abstract
3D full field deformation measurement using digital image correlation
(Department of Civil Engineering, University of Moratuwa, 2021-11) Lowhikan, SS; Mallikarachchi, HMYC; Hettiarachchi, P
3D deformation and strain are crucial parameters in engineering design and construction. Precise 3D full-field measurement is useful in identifying the response of the structure under a given loading condition. Digital Image Correlation (DIC) is a non-contact optic-based technique that may prove to be ideal for full-field deformation applications. It has the potential to become an inexpensive, simple, and accurate solution for deformation measurement. All DIC measuring systems now available consist of expensive software packages and experimental facilities which are difficult to access. Therefore, a cost-effective method must be developed to use in the local context efficiently. This research mainly focuses on the development and validation of the cost-effective precise noncontact- based deformation measurement technique. In the proposed method, 3D full-field deformation of the deforming object is measured using two digital cameras and an image processing toolbox available in the MATLAB commercial package. Further, the proposed method efficiency is enhanced by developing it as a standalone application, which can be installed and used by any technician conveniently and utilized for various laboratory Civil Engineering applications. Enhancing the proposed DIC algorithm to improve resolution in 3D applications and extending to phase-changing materials and developing Graphical User Interface (GUI) and general guidelines to be used by a technician were defined as objectives of this research. The proposed measuring system consists of two digital cameras mounted on a rigid frame as it is targeted to capture the specimen and connected to a computer. A random speckle pattern must be applied on the specimen’s surface to track the deformation. The proposed image processing algorithm was developed in MATLAB by using a computer vision toolbox. Later Graphical User Interface was developed using MATLAB App Designer. The developed system was used to obtain the results and validated for rigid body motion tests of concrete cube and cylinder, compression test of concrete, uni-axial tensile test of a dog bone aluminium specimen and shrinkage cracks of mortar experiments. In conclusion, a cost-effective and reliable measurement system was developed by using DIC techniques and MATLAB computer vision toolbox, with its performance validated experimentally by assessment of measurements of the in-plane strain of materials. Even though it has some limitations, the developed algorithm and application can be effectively used for laboratory-scale Civil Engineering related experiments. Also, the application that was developed can be handled by technicians who do not have much knowledge nor understanding of programming languages. The Graphical User Interface that was developed is easy to use and saves considerable time. The performance of the system that has been developed can be assessed and improved for greater precision.
item: Conference-Full-text
3D full-field deformation measurement using stereo vision
(IEEE, 2022-07) Sarma, LS; Mallikarachchi, C; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Measuring 3D deformation and strain are crucial parameters in structural engineering applications both at the construction and operational stages. Precise 3D full-field measurements are useful in structural optimization, damage detection and retrofitting. Digital Image Correlation is a non-contact optic-based measurement technique that is proven to be an ideal candidate in this regard. It has the potential to become a cheap, simple, and precise solution for deformation measurement. However, the currently available Digital Image Correlation measuring systems require expensive dedicated software packages and physical resources which are difficult to access. Therefore, there is a need to develop a cost-effective measuring technique to effectively use it in the local context. This research focuses on the development and validation of a precise non-contact-based deformation measurement technique. In the proposed method, 3D full-field deformation of the deforming object is measured by processing stereo photographs taken with commonly available digital cameras using the image processing toolbox available in the MATLAB commercial package. Further, the proposed method is enhanced by developing it as a standalone application, which can be installed and conveniently used by any technician. Capability of using the developed application in common civil engineering laboratory experiments has been demonstrated.
item: Conference-Full-text
3d full-field deformation measuring technique using digital image correlation
(IEEE, 2020-07) Nadarajah, S; Arulkumar, V; Mallikarachchi, C; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Full-field deformation measurements are crucial as it offers detailed information to better understand both micro and macroscopic nature of material behavior. The practice of employing Digital Image Correlation (DIC) based measuring techniques in experiments has increased due to its ability to generate full-field deformation information with minimal effort. Even though DIC systems are commercially available, the affordability of those systems is questionable in local context due to high capital costs. Most of the past studies related to DIC were focused on testing concrete, masonry and metallic alloy specimens, and little effort has been made on materials with recoverable large elongations. This paper presents a 3D fullfield deformation measuring system that has been developed with a special focus on hyperelastic materials. The proposed system requires two common digital cameras for image acquisition, as the depth information is of interest. Images are then processed using the MATLAB-based algorithm developed to produce the full-field deformation map. Hyperelastic specimens of two different thicknesses were tested over 70% strain and the accuracy of the strain measurement using the proposed system is validated against physical measurements. The results have shown that the strains can be captured to an accuracy greater than 90% using the proposed technique.
item: Conference-Full-text
3d full-field deformation measuring technique with optics-based measurements
(IEEE, 2018-05) Randil, OPC; Mallikarachchi, HMYC; Chathuranga, D
Full-field deformation measurements plays a vital role in designing, monitoring and retrofitting many engineering products ranging from civil engineering structure to aerospace applications. Optics-based measurements have gained a vast popularity over last two decades. This paper attempts to establish a method in measuring displacements in a 3D environment, using optics-based measurements, in a cost-effective manner. The study focuses on measuring displacements of a moving object with two stationary cameras. Images acquired from two cameras are processed through MATLAB software package and selected region of the object is reconstructed in a virtual 3D environment at each step. Digital image correlation technique is then adopted to measure displacement by comparing the coordinates of reconstructed objects in each step. It is shown that the displacements can be measured to an accuracy of 0.15 mm (in 20 mm) for the selected object giving an accuracy of 98%.