Browsing by Author "Mendis, P"

Now showing 1 - 20 of 25

item: Conference-Abstract
Adaptive model predictive control with successive linearization for distillate composition control in batch distillation
Mendis, P; Wickramasinghe, C; Narayana, M; Bayer, C
This paper investigates the application of adaptive model predictive control (MPC) with successive linearization for the control of top product purity of a batch distillation column. Adaptive MPC with successive linearization can overcome the prediction inaccuracies associated with linearization of highly non-linear and dynamic mathematical model of a batch distillation column, with a lower computational load than nonlinear MPC. A binary mixture of methanol and water was selected to demonstrate the controller development, and its performance was investigated by varying MPC tuning parameters in the MATLAB/Simulink simulation environment. Results indicated that the choice of tuning parameters had a considerable influence on the MPC’s ability to track a constant set-point for the output. With the correct choice of tuning parameters, however, it is possible for the controller to track a constant set-point. The present approach is compared with nonlinear MPC in order to gain a quantitative understanding on accuracy and computational effort.
item: Article-Full-text
AI-powered smart recycling: turning plastic trash into treasure
(University of Moratuwa, 2023) Kristombu, S; Thilakarathne, BS; Perera, S; Mendis, P; Ruwanpathirana, G; Rohanawansha, H; Wijesinghe, N; Mallikarachchi, C; Weerasinghe, P; Herath, S
In a world grappling with environmental challenges posed by plastic waste, innovative solutions are emerging to address the pressing issue of plastic recycling. Among these solutions, Smart AI-enabled automation and Upcycling stand out as promising technologies that offer the potential to revolutionize the way we handle and repurpose plastics. These technologies harness the power of artificial intelligence (AI) and automation to streamline the recycling process and transform discarded plastic materials into valuable products.
item: Conference-Full-text
Application of nano insulation materials in the sustainable Built environment
(2013-11-19) Gammampila, R; Mendis, P; Ngo, T; Aye, L; Herath, N
Nanotechnology is widely being used in the built environment for its advantages in many improved engineering properties of the nano materials. Nano insulating materials open up new possibilities for ecologically oriented sustainable infrastructure development. The most widely used nano material in built environment is for the purpose of insulation to improve the energy efficiency namely in the buildings and dwellings. Nanotechnology has now provided an effective and affordable means to increase energy efficiency in pre-existing buildings as well as new construction by increasing thermal resistance. The major advantage of nano insulation materials is its benefit of translucent coatings which increase the thermal envelope of a building without reducing the square footage. The intrinsic property of nano insulating material is it can be applied to windows to reduce heat transfer from solar radiation due it its thermal resistant property and the translucent property allows diffusing of day light. The nano insulating material has significant advantage in reducing the operational energy aspects of buildings due to its valuable insulating properties. This paper examines applicable nanotechnology based products that can improve the sustainable development and overall competitiveness of the building industry. The areas of applying nano insulating material in building industry will be mainly focused on the building envelope. The paper also examines the potential advantages of using nanotechnology based insulating material in reducing the life cycle energy, reduction of material usage and enhancing the useable life span. The paper also investigates the operational energy by simulation methodology and compares the reduction of operational energy consumption.
item: Conference-Full-text
Application of nanomaterials in the sustainable built Environment
(2013-11-19) Gammampila, R; Mendis, P; Ngo, T; Aye, L; Jayalath, AS; Rupasinghe, RAM
Nanotechnology is widely regarded as one of the twenty-first century’s key technologies, and its economic importance is sharply on the rise. In the construction industry, nanomaterials has potentials that are already usable today, especially the functional characteristics such as increased tensile strength, self-cleaning capacity, fire resistance, and additives based on nano materials make common materials lighter, more permeable, and more resistant to wear. Nonomaterial are also considered extremely useful for roofs and facades in the built environment. They also expand design possibilities for interior and exterior rooms and spaces. Nano–insulating materials open up new possibilities for ecologically oriented sustainable infrastructure development. It has been demonstrated that nanotechnology has invented products with many unique characteristics which could significantly provide solutions current construction issues and may change the requirement and organization of construction process. This paper examines and documents applicable nanotechnology based products that can improve the sustainable development and overall competitiveness of the construction industry
item: Conference-Abstract
Applications of design for excellence in prefabricated building services systems
Samarasinghe, T; Mendis, P; Lu, A; Vassos, T
Prefabrication is a sought after area in the AEC industry for manufacture of building components in an off-site controlled environment. Although, most of the structural element such as panels and modules are efficiently prefabricated and assembled onsite, prefabrication of complete mechanical, electrical and plumbing (MEP) systems is not achieved in many cases. This is mainly due to the limitations during assembly of different systems, poor implementation of building information modelling (BIM) and lack of standards for offsite manufacturing. The research will introduce the concept of Design for Excellence (DFX) which is currently used efficiently in the automotive, aerospace and shipbuilding industries. Applications of the DFX concept for building services in residential buildings were studied. This paper presents the overall concept of holistic approach to arrive at an optimum solution for design integrated building services systems for prefabricated buildings.
item: Conference-Full-text
Applications of phase change materials in concrete for sustainable built environment : a review
(2013-11-23) Jayalath, A; Mendis, P; Gammampila, R; Aye, L
The fast economic development around the globe and high standards of living imposes an ever increasing demand for energy. As a prime consumer of world‟s material and energy resources building and construction industry has a great potential in developing new efficient and environmentally friendly materials to reduce energy consumptions in buildings. Thermal energy storage systems (TES) with Phase change materials (PCM) offer attractive means of improving the thermal mass and the thermal comfort within a building. PCMs are latent heat thermal storage (LHTS) materials with high energy storage density compared to conventional sensible heat storage materials. Concrete incorporating PCM improves the thermal mass of the building which reduces the space conditioning energy consumption and extreme temperature fluctuations within the building. The heat capacity and high density of concrete coupled with latent heat storage of PCM provides a novel energy saving concepts for sustainable built environment. Microencapsulation is a latest and advanced technology for incorporation of PCM in to concrete which creates finely dispersed PCMs with high surface area for greater amount of heat transfer. This paper reviews available literature on Phase change materials in concrete, its application and numerical modelling of composite concrete. However most of the existing TES systems have been explored with wallboards and plaster materials and comparatively a few researches have been done on TES systems using cementitious materials. Thus, there is a need for comprehensive experimental and analytical investigations on PCM applications with cementitious materials as the most widely used construction materials in buildings.
item: Conference-Full-text
BIM Software Framework for Prefabricated Construction: Case Study Demonstrating BIM Implementation on a Modular House
(2016-01-05) Samarasinghe, T; Mendis, P; Ngo, T; Fernando, WJBS
Building information modeling and prefabrication are concepts that are undergoing intense study in the construction industry. As the technology to implement BIM is commercially available, many industries have started to use BIM in construction related projects. However, BIM implementation can vary significantly according to the nature of the project. Therefore, development of a BIM software framework for a particular industry to meet its requirements is the most efficient way to use Building Information Modeling. This paper will present a BIM software framework developed for prefabricated construction industry and will demonstrate the use of the framework during the design stage of a modular pre-fab house.
item: Conference-Full-text
Computational modelling of the mechanical environment of the early stage of fracture healing using structural engineering techniques
(2013-12-06) Miramini, S; Zhang, L; Mendis, P; Richardson, M
Bone healing is a complex biological process which is regulated by mechanical micro-environment caused by inter-fragmentary movement (IFM). IFM generated interstitial fluid flow within the fracture callus could potentially not only affect the mesenchymal stem cells migration and differentiation during the healing, but also enhance nutrient transport within the callus tissue. In this study, a three dimensional poroelastic finite element model of a human tibia was developed to study the mechanical behaviour of the fracture callus due to IFM at the early stage of fracture. The biophysical stimuli were characterised with three main parameters involved in the healing process: octahedral shear strain, interstitial fluid velocity and pressure. The proposed algorithm represents a first step towards to the development of a powerful simulation tool for fracture healing.
item: Conference-Full-text
Experimental investigation on the behavior of RC panels retrofitted with polymer coatings under blast effects
(2013-11-13) Raman, SN; Pham, T; Mendis, P; Ngo, T
Elastomeric polymers (such as polyurea and polyurethane) are finding relevance in retrofitting applications for structures being subjected to blast and impact loadings. This approach, an alternative to various existing retrofitting techniques, capitalises on the elastomeric properties, high strain capacity, high ductility and strength of the polymers, as well as on the ability of the coating layer to act as a shield in containing debris and fragments from the blast. This paper presents the findings from an experimental study undertaken to evaluate the effectiveness of using polyurea coatings to enhance the blast resistance of reinforced concrete (RC) panels. The performed experimental blast trials, designated as Vietnam Trial 2, were conducted in Vietnam with the collaboration from the Vietnam Institute for Building Science and Technology (IBST). Four RC panels with dimensions of 1700 (L) 1000 (W) 60 (T) mm, were tested during the trials. Of these, one panel was an unretrofitted panel while the remaining three were coated with polyurea albeit with a variation in the coating thickness and location. All the panels were subjected to blast loads resulting from the detonation of 1.0 kg Ammonite charge placed at 1.0 m stand-off. The behaviour and responses of various polyurea coated RC panels were compared to the unretrofitted RC panels in terms of panel’s deflections, crack formation and damage to the polyurea coating layers. The findings from the experiments indicated that proposed technique of using polyurea coating to retrofit RC structural elements is practicable and feasible to enhance the capacity of structures against blast loading. A higher level of protection is provided when the protective coating is applied on the blast-facing face of the structure. It was also observed that the bond between concrete and the polymer did not damage even after the the application of the blast loads. These findings assert the possibility of using the proposed technique as a practical alternative to the existing techniques in strengthening structures being subjected to blast effects.
item: Conference-Full-text
Framework for analysis of demolition supply chain to optimize use of recycled concrete aggregate (RCA) and recycled aggregate (RA)
(2013-11-13) Wijayasundara, M; Mendis, P; Zhang, L
The paper discusses the factors that affect the recycling rate of recycled aggregates (RA) and recycled concrete aggregates (RCA) derived from demolition waste of reinforced concrete buildings. The recycling rate for construction and demolition waste presently stand at 57% in Australia, where countries such as Japan has achieved 98% recycling rates for demolition waste. A framework is proposed to investigate demolition waste management supply chain as a whole and to critically analyse and investigate the factors affecting the recycling rate of concrete and fines to produce RA and RCA from demolition waste. The factors affecting the recycling rate of concrete and fines across the waste supply chain are categorised into technical, economic and regulatory and policy related factors. The framework proposed is to analyse the inter-relationships between these factors.
item: Conference-Full-text
High strength concrete for sustainable construction
(2013-11-26) Wu, D; Sofi, M; Mendis, P
The use of HSC for construction, especially for multi-story buildings, has become very common in industrialized and developing countries. In view of gaining popularity as a construction material, high strength concrete (HSC) properties are discussed in this paper. A brief review of literature is presented. The necessary ingredients of HSC such as fly ash, slag and silica fume which are mostly industrial byproducts make the product environmentally friendly. The main engineering properties of the HSC are also reviewed.
item: Conference-Full-text
A holistic model for designing and optimising sustainable prefabricated modular buildings
(2013-11-13) Gunawardena, T; Ngo, T; Mendis, P; Aye, L; Crawford, R; Alfano, J
Prefabricated Modular Structures are increasingly becoming popular as a strategy that can be used to achieve cost effective and speedy construction. However, there is an absence of detailed engineering research or case studies dealing with the structural performance or building optimisation and integration strategies for this technology. This paper presents a conceptual holistic model that can be used to identify the most optimum structural system in a given scenario. A multi-disciplinary approach will be taken to optimise the building by assessing structural systems, materials, sustainability features, constructability and speed and cost of construction. This paper will discuss types of different optimisation strategies adopted in building designs and how they can be modified to assess a prefabricated modular building and what different variables will dominate as key performance indicators in the search for an optimum solution for a prefabricated modular building.
item: Conference-Full-text
ICSECM 2015 - Wind Design of Slender Tall Buildings: CFD Approach
(2016-01-05) Mohotti, D; Danushka, K; Mendis, P
Urbanization has led to the uprising of such buildings in densely populated areas where land availability and prices are a concern in such areas. Where such concerns exist the land must be fully exploited and thus constructions of tall buildings are always found as a solution in such areas. Wind behaviour is a key designing parameter for such building and need to be assessed accurately in the preliminary and secondary design stages. As most of the existing design codes have their own limitations in providing necessary guidelines for the wind designing, such as height limits of the buildings, the existing practice is to conduct wind tunnel tests to determine the wind induced loads on the buildings. However, the cost of the wind tunnel test is comparatively high and conducting wind tunnel tests at preliminary design stage is uneconomical. The rapid growth of Computation Fluid Dynamic (CFD) technique over the last few decades enables Engineers to simulate the wind behaviour around moving objects such as aeroplanes and automobiles. Therefore use of such methodology to predict wind loads on the buildings, especially at the preliminary design stages could be beneficial. This paper discusses a preliminary investigation that carried out on a non-typical 350m tall slender building using CFD approach.Urbanization has led to the uprising of such buildings in densely populated areas where land availability and prices are a concern in such areas. Where such concerns exist the land must be fully exploited and thus constructions of tall buildings are always found as a solution in such areas. Wind behaviour is a key designing parameter for such building and need to be assessed accurately in the preliminary and secondary design stages. As most of the existing design codes have their own limitations in providing necessary guidelines for the wind designing, such as height limits of the buildings, the existing practice is to conduct wind tunnel tests to determine the wind induced loads on the buildings. However, the cost of the wind tunnel test is comparatively high and conducting wind tunnel tests at preliminary design stage is uneconomical. The rapid growth of Computation Fluid Dynamic (CFD) technique over the last few decades enables Engineers to simulate the wind behaviour around moving objects such as aeroplanes and automobiles. Therefore use of such methodology to predict wind loads on the buildings, especially at the preliminary design stages could be beneficial. This paper discusses a preliminary investigation that carried out on a non-typical 350m tall slender building using CFD approach.
item: Conference-Full-text
Improving the safety of buildings through an innovative sustainable facade system
(2013-11-26) Mohotti, D; Lunmantara, R; Ngo, T; Mendis, P
A building’s façade system is the outer layer of a structure that is designed to provide protection to building occupants and contents from external hazards with varying intensity. In the modern world, many structures undergo different types of dynamic loadings such as blast and ballistics, earthquakes, high winds, hurricanes, tsunamis etc. It is a prime importance of the modern structures to sustain those dynamic loadings without excessive damage. Due to the recent trend towards sustainable development, there are more prevalent uses of innovative systems such as the double skin façade systems, which lead to new challenges in assessing the performance of these façade systems under extreme loadings. This paper presents a review of innovative double layer skin façade system with some finite element modeling to assess the behaviour.
item: Conference-Full-text
Innovative modeling and visualization platform for sustainable cities - Mutopia
(2013-11-13) Mendis, P; Ngo, T; Aye, L; Malano, H; Rajabifard, A
Now more than half the world’s population lives in towns and cities and this proportion will rise to nearly two thirds by 2030. Many cities worldwide are facing acute challenges, and therefore it is essential that all future developments are carried out on a sustainable footing. Through a web-based platform, MUtopia visualises and demonstrates in a quantifiable manner what impact a planned site development would have by representing best practice in all aspects of sustainable urban living on a relatively large scale. Sites may be new suburbs or rebuilt sections of the city large enough to require systematic planning. The project focuses on the development of an integrated modelling, analysis and visualization tool that helps the government and developers to make informed decisions to achieve such sustainable urban development and implementation. MUtopia integrates the streams of energy, waste, water and transport, based on land use, as well as social and environmental factors so that various planning scenarios or dependencies between factors can be tested. It is an integrated BIM and GIS tool. MUtopia would be an international first in an area of growing interest and need.
item: Conference-Full-text
Innovative prefabricated modular structures – an Overview and life cycle energy analysis
(2013-12-06) Gunawardena, T; Ngo, T; Aye, L; Mendis, P
Speed of construction and improved environmental performance are two critical concerns which modern construction industry pays a significant amount of attention on. Employing innovative prefabricated modular structures is one key strategy used to achieve these goals. However, there is an absence of detailed scientific research or case studies dealing with the potential environmental benefits of prefabrication, particularly in the areas of embodied energy savings resulting from waste reduction and improved efficiency of material usage. This paper gives a brief overview of prefabricated modular structures and aims to quantify the embodied energy of modular prefabricated steel and timber multi-residential buildings in order to determine whether this form of construction provides improved environmental performance over conventional concrete construction methods. A case study was carried out on an eight-storey, 3943 m2 multi-residential building. It was found that a steel-structured prefabricated system resulted in a significantly reduced material consumption of up to 78% by mass compared to conventional concrete construction. However, the prefabricated steel building resulted in an increase (~50%) in embodied energy compared to the concrete building. This form of construction has the potential to contribute significantly towards improved environmental sustainability in the construction industry.
item: Conference-Full-text
Monitoring of a tall building to develop axial shortening models incorporating high strength concrete
(2013-11-26) Baidya, N; Mendis, P; Fragomeni, S
This paper addresses axial shortening prediction of the vertical concrete elements of tall buildings with a particular focus on developing a reliable model for high strength concrete (HSC). An established reinforced concrete column shortening model used for normal strength concrete (NSC) is modified to predict axial shortening in vertical elements made of HSC. To compare with the theoretical model, the axial shortening measurements taken from the 83 storey World Tower Building, Sydney (WTS), obtained during the construction period, are used. The theoretical model having the best match with the actual measurements are recommended for predicting axial shortening of vertical elements using HSC.
item: Conference-Full-text
Nanoengineering concrete for sustainable built environment: a review
(2013-11-23) Rupasinghe, M; Mendis, P; Gammampila, R; Ngo, T
The construction industry is a major consumer of material and energy sources in the world. Among all the materials used in construction, concrete, which is the most widely used, can have a significant impact. Meanwhile, nanotechnology is one of the most influential technologies in this century and it has significantly impacted the construction sector. Better understanding and engineering cementitious materials at nanometer scale can result in novel construction materials which are more strong and durable than conventional materials. Engineering concrete at the nano meter scale includes the incorporation of nano sized particles into concrete at suitable proportions and methods. Nano Silica is one such nano material which has shown to enhance the overall performance of concrete. Incorporation of nano Silica at smaller volume fractions has shown to result in higher compressive and flexural strengths at early ages, improved hydration characteristics and reduced porosity and water absorption when compared with conventional cementitious materials. The impacts of other nano materials such as CNTs, nano TiO2, nano Al2O3 and nano TiO2 on concrete are also promising. While nano materials acts as fillers and provide nucleation sites for cement hydration, nano SiO2 also acts as a pozzolanic material, increasing the amount of stiff CSH within the hydrated cement paste, resulting an improved microstructure. Nanomaterials can also pave the path to reduce the cement content in concrete than in conventional mixes while maintaining same strength characteristics, which will lead into the production of a „greener‟ concrete. Numerical models of the composite material validated with experimental results can be used to come up with optimum nano material contents and performance. This paper reviews the efforts, current status and effects of nano modification of cementitious materials and numerically modelling strength properties. These innovative materials will be of high performance and less energy consuming, which will lead towards sustainable construction practices.
item: Conference-Full-text
Numerical simulation of failure mechanisms of a typical dead end anchorage of post-tensioned suspended slabs
(2013-12-06) Sofi, M; Mendis, P; Baweja, D; Elvira, E
The post-tensioning loads in suspended slabs are transferred to concrete mass via an anchorage assembly that consists in a strand and anchor component. Many failures have occurred in the dead-end anchors of post-tensioned (PT) suspended slabs during the post-tensioning process which need a closer study. This study attemps to simulate the crack propagation near the deadend anchors of PT suspended slabs. The bond behaviour of strand and wire is develioped using experimental test. Interface element is used to model the bond between concrete and strand/ wire. The analysis is conducted using displacement controlled procedure. The result shows that the crack on the concrete is concentrated near the dead-end anchors.
item: Conference-Full-text
Numerical simulation of impact and penetration of ogvial shaped projectiles through steel plate structures
(2013-12-06) Mohotti, D; Ngo, T; Mendis, P
There is an urgent need to develop light-weight protective structures with a sufficient protection to prevent the damage occurring during extreme loading events such as blast and ballistic impacts. This study is a part of ongoing research to develop light weight amour materials which can sustain under those severe conditions. Numerical modelling with explicit finite element code LS-DYNA has performed with realistic geometries. Ballistic protection class BR7 in European norm EN 1063 considered, thus penetration of different shaped projectiles through thick steel plates was examined. Since the geometries and materials of the projectiles have a very significant influence on the outcome of this research detail modelling of the projectiles was performed. For the purpose of this paper, perforation mechanism of 7.62mm APM2 bullet through 6mm thick Weldox 460E high strength structural steel plate was examined. Largrangian methods combined with Johnson-Cook material model available in the LS-DYNA were used for the numerical simulations. Finally the ballistic limit curve for the 6mm thick Weldox 460E plate perforated by APM2 bullet was obtained. Results were compared with the analytical models.