Research Papers - Department of Mechanical Engineering
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Publication Open Access Passive techniques for residential buildings in low altitudes of Sri Lanka(Institution of engineers: Colombo, 1999) Jayasinghe, M.T.R; Attalage, R. AThe role of passive techniques, which utilises a certain number of passive elements to maintain the thermal comfort within the built environments of residential buildings at low atlitudes of Sri Lanka, has been highlighted. The possibility of defining a unique neutral temperature of 26°C for low altitutes of Sri Lanka has been utilised in a rational way in presenting simplified set of rules of thumb, that can be used by the designers at early stages. The effects of orientation, shading devices, window sizes, roofing materials, insulation, colour of the exterior and interior walls, use of courtyards to maximise natural ventilation, and arrangement of roof to minimise structural cooling are shown with suitable examples.Publication Open Access Comfort conditions for built environments in Sri Lanka(Institution of Engineers, 1999) Jayasinghe, M.T.RThe neutral temperatures for different locations in Sri Lanka have been established using actual climatic data. Based on these neutral temperatures, 'standard comfort zone for each of these locations can be identified on the psychrometric chart. Field measurements have been carried out for the validation of comfort zones for Sri Lankan conditions. The effects of physiological cooling at relatively high internal air velocities have been highlighted. In order to check the applicability of standard modification techniques for the comfort zones to take account of elevated internal air velocities, surveys have been carried out at two different velocities. The need for additional boundaries to standard modifications to suit Sri Lankan conditions have been highlighted. This provides a method of extending the boundaries of these comfort zones thereby accommodating higher levels of dry bulb temperatures and humidites in the built environments. This fact can be utilised as the basis of minimising the energy demand in buildings either air conditioned or not, by making use of combined modes at different internal air velocities.Publication Embargo Component part standardization: A way to reduce the life-cycle costs of products(Elsevier, 1999-04-20) Perera, H. S. C; Nagarur, N; Tabucanon, M. TThis paper studies the effects of component part standardization on life-cycle costs. Three possible situations for component standardization are discussed. A summary is presented of various costs in different phases of the product life cycle and how they are shared among the manufacturer, user, and society. Then, we explain how the component standardization reduces the costs of different phases of the product life cycle. Finally, we point out some of the possible disadvantages of component standardization.Publication Open Access Potential of biomass fuel conservation in selected Asian countries(Pergamon, 1999-07-01) Bhattacharya, S. C; Attalage, R. A; Leon, M Augustus; Amur, G. Q; Salam, P Abdul; Thanawat, CThe potential of savings in the biomass consumed for energy in seven Asian countries—China, India, Pakistan, Nepal, Philippines, Sri Lanka and Vietnam—is estimated, if the centuries-old traditional methods of biomass use are reconsidered and an efficient, rational use is implemented. The present pattern and share of biomass consumption of different traditional biomass energy devices are recorded. The efficiency of traditional technologies and that of improved ones—technologies which are practically applicable or already in use somewhere else—are compared and the potential of biomass savings is calculated. The total biomass saving potential in all seven countries together has been estimated at 322 million tons/yearPublication Open Access Potential of biomass fuel conservation in selected Asian countries(Pergamon, 1999-07-01) Bhattacharya, S. C; Attalage, R. A; Leon, M Augustus; Amur, G. Q; Salam, P Abdul; Thanawat, CThe potential of savings in the biomass consumed for energy in seven Asian countries—China, India, Pakistan, Nepal, Philippines, Sri Lanka and Vietnam—is estimated, if the centuries-old traditional methods of biomass use are reconsidered and an efficient, rational use is implemented. The present pattern and share of biomass consumption of different traditional biomass energy devices are recorded. The efficiency of traditional technologies and that of improved ones—technologies which are practically applicable or already in use somewhere else—are compared and the potential of biomass savings is calculated. The total biomass saving potential in all seven countries together has been estimated at 322 million tons/yearPublication Open Access A Cost Model for Evaluating Component Standardisation: A Case Study(O. P. A, 2000) Nagarur, N. N; Perera, H. S. C; Tabucanon, M. TAs manufacturing industry tries to grapple the oftenconflicting objectives of increasing product variety and reducing the production costs, one of the strategies oft contemplated is component standardization or using common components. However, developing and using standard components may sometimes push the overall costs actually higher. This paper proposes an evaluation model for decision making in the context of component standardization. First, it discusses various types of costs to be considered for selecting desired components. Then the paper presents a specific case study in which some purchasing parts are considered for standardization. An evaluation model is developed for the relevant costs of the case. The solution and sensitivity analysis are presented and discussed.Publication Embargo Analysis of household cooking energy demand and its environmental impact in Sri Lanka(Pergamon, 2002-11-01) Attalage, R. A; Wijayatunga, Priyantha DCThis paper presents the results and analysis of a study conducted with the objective of investigating the cooking energy requirements in the Sri Lanka domestic sector and the environmental emissions associated with it. The study was conducted out through a sample and showed that the main household energy supply sources were biomass, liquefied petroleum gas (LPG), electricity and kerosene with electricity being used largely for water boiling in all subsectors. It was observed that the urban sector cooking is largely dominated by LPG (95% of urban households) while the rural sector cooking is confined mainly to biomass (95% of rural households). The suburban sector consists of a mixture of all the sources (LPG-70% and biomass-85% of suburban households). Similarly, LPG dominates in electrified households (76.4% of electrified households), while biomass dominates in all non-electrified households. It was found in the analysis that the highest level of gaseous emissions due to cooking activity occurs in the rural areas, mainly due to the relatively large use of biomass, while the lowest level of emissions is recorded in a typical suburban household. Also, the analysis shows that fuel switching in domestic cooking activities from biomass to LPG and kerosene can be used as a measure to reduce emissions due to higher stove efficiencies and lower emission factors associated with these fuels. Substitution of 50% of biomass usage by kerosene in the rural households will result in 39–50% reduction in emissions within the rural sector. Further, substitution of 50% of biomass usage in urban and suburban sectors by LPG results in 4–49% reduction in emissions within these sectors.Publication Embargo [PDF] from researchgate.net Roof orientation, roofing materials and roof surface colour: their influence on indoor thermal comfort in warm humid climates(Elsevier, 2003-03-01) Jayasinghe, M T R; Attalage, R. A; Jayawardena, A IThe excessive heat transferred through the roof is one of the main causes of thermal discomfort in warm humid climatic conditions, which prevail in the tropical zone. Therefore, the selection of the most appropriate roof orientation and materials will be important for desirable thermal performance of passive houses. This study investigates the effect of the roof orientation, roofing materials, insulation and the surface colour of the roof on the maximum indoor temperature of a house located in a warm humid climatic region. It is shown with the aid of computer simulations that the roof orientation has no significant effect on a properly planned passive house. However, the use of appropriate materials and insulation could afford significant improvement, which could be further enhanced with the use of light colours for the roof surface.Publication Embargo Analysis of rural household energy supplies in Sri Lanka: energy efficiency, fuel switching and barriers to expansion(Pergamon, 2003-05-01) Attalage, R. A; Wijayatunga, Priyantha DCA majority of the households in Sri Lanka, as in the case of many developing countries, is concentrated in the rural areas of the country. Unfortunately, very little attention has been paid until recently to analyse and address various issues associated with rural energy supplies, particularly those issues regarding barriers to penetration of clean and convenient sources of energy. This paper presents the results and analysis of a study conducted through a sample study on domestic energy supplies in rural Sri Lanka with emphasis on cooking and lighting energy requirements. The paper has attempted to highlight policy issues associated with rural energy supplies and possible solutions to them in the context of the country’s overall picture of the energy sector.Publication Embargo Socio-economic impact of solar home systems in rural Sri Lanka: a case-study(Elsevier, 2005-06-01) Attalage, R. A; Wijayatunga, Priyantha DCThe use of solar photovoltaic systems of 25 Wp to 50 Wp (frequently called solar home systems, or SHSs) has been spreading fast in the rural areas of Sri Lanka as a source of energy used for domestic lighting, mainly because of the financial incentives provided by the donor agencies and aggressive marketing strategies of the SHS dealers in rural areas. This paper presents the outcome and the analysis of a study conducted with the objective of investigating the social, economic and environmental impact of SHSs in rural Sri Lanka. The study involved conducting a survey of 125 households having SHSs, in the Uva province of Sri Lanka, through personal visits. It was evident that the households are extremely satisfied with the technology that has replaced their kerosene lamps, which had been providing household lighting requirements. The quality of life, in terms of activities such as longer study hours of children, longer TV watching hours for the family and lessening the risk of fatal kerosene lamp accidents, has improved with the introduction of the SHSs. It is concluded that the large-scale penetration of solar home systems in Sri Lanka has helped rural communities both in terms of improved socio-economic conditions and reduced adverse environmental impacts, contrary to the belief that the financial burden of such systems imposed on the families outweighs the benefits. But when comparing the benefits of SHSs against the extension of the national grid, the country needs to seriously examine its options for the areas currently targeted by SHS dealers.Publication Embargo Strategies to overcome barriers for cleaner generation technologies in small developing power systems: Sri Lanka case study(Pergamon, 2006-06-01) Wijayatunga, Priyantha DC; Siriwardena, Kanchana; Fernando, W J L S; Shrestha, Ram M; Attalage, R. AThe penetration of cleaner and energy efficient technologies in small power systems such as the one in Sri Lanka has encountered many problems. This has caused major concerns among the policy makers, mainly in the context of the growing need to reduce harmful emissions in the electricity supply industry from the point of view of both local environmental pollution as well as the global warming concerns. This paper presents the outcome of a study involved in identifying and ranking the barriers to the promotion of cleaner and energy efficient technologies and strategies to overcome these barriers in Sri Lanka. Barriers for renewable energy based systems such as wind and wood fuel fired plants (dendro thermal power) and cleaner technologies such as liquefied natural gas (LNG) fired combined cycle and IGCC (coal) were identified based on a survey. A direct assessment multi-criteria decision making method called Analytic Hierarchy Process (AHP) was used to rank the barriers. The most effective strategies are proposed to address the three major barriers for each of these technologies based on extensive discussions with all the stakeholders in the electricity industry. It was found that lack of financing instruments, high initial cost and lack of assurance of resource supply or availability are the main barriers for renewable technologies. As for cleaner fuel and technology options associated with conventional generation systems, the lack of a clear government policy, uncertainty of fuel supplies and their prices and the reliability of the technologies themselves are the major barriers. Strategies are identified to overcome the above barriers. Establishment of a proper feed in tariff, geographical diversification of installations and capacity building in commercial banks are suggested for wind power. Investment incentives, streamlining of wood production and research on site identification are proposed for wood fuel fired plants. Also the study suggests delayed implementation, combined planning with other sectors of the economy, incorporating environmental cost in planning and investment incentives as strategies for IGCC and LNG based technologies.Publication Embargo Scenario-based analyses of energy system development and its environmental implications in Thailand(Elsevier, 2007-06-01) Shrestha, R. M; Malla, S; Liyanage, M. HThailand is one of the fastest growing energy-intensive economies in Southeast Asia. To formulate sound energy policies in the country, it is important to understand the impact of energy use on the environment over the long-period. This study examines energy system development and its associated greenhouse gas and local air pollutant emissions under four scenarios in Thailand through the year 2050. The four scenarios involve different growth paths for economy, population, energy efficiency and penetration of renewable energy technologies. The paper assesses the changes in primary energy supply mix, sector-wise final energy demand, energy import dependency and CO2, SO2 and NOx emissions under four scenarios using end-use based Asia-Pacific Integrated Assessment Model (AIM/Enduse) of Thailand.Publication Embargo Economy wide emission impacts of carbon and energy tax in electricity supply industry: A case study on Sri Lanka(Pergamon, 2007-07-01) Siriwardena, K; Wijayatunga, P. D.C; Fernando, W.J.L.S; Shrestha, R. M; Attalage, R. AThis paper presents the results and analysis of a study conducted with the objective of investigating the impact on economy wide emissions due to carbon and energy taxes levied within the electricity generation sector of Sri Lanka. This exercise is mainly based on the input–output table developed by the national planning department. An input–output decomposition technique is used to analyze four types of effects that contribute to the overall reduction in equivalent carbon, NOx and SO2 emissions. These four effects are: fuel mix effect (i.e. the change in emissions due to variation I fuel mix), structural effect (i.e. change in emissions due to changes in technological coefficients with taxes compared to that without taxes), final demand effect (i.e. the change in emissions associated with changes in final demand) and joint effect (i.e. the interactive effect between or among the fuel mix, structural and final demand effects). The polluting fuel sources and low energy efficiency generation technologies are less preferred under these tax regimes. Of the four effects, a change in fuel mix in thermal electricity generation and a change final demand for electricity were found to be the main contributors in achieving economy wide emission reductions. It was found in the analysis that a minimum of US$ 50/tC tax or US$ 1.0/MBtu of energy tax is required to have a significant impact on economy wide emissions in the Sri Lankan context. This translates into an overall increase in electricity generation cost of approximately USCts 0.9 kW−1 h−1 and USCts 0.6 kW−1 h−1 under the carbon and energy tax regimes, respectively. The reduction in emissions is also strongly coupled with the value of the price elasticity of electricity.Publication Embargo Effects of carbon tax on greenhouse gas mitigation in Thailand(Taylor & Francis Group, 2008-01-01) Shrestha, R. M; Pradhan, S; Liyanage, M. HThis study analyses energy system development and the associated greenhouse gas emissions in Thailand under a reference case and three different carbon tax scenarios during 2013–2050 using a bottom-up cost-minimizing energy system model based on the Asia–Pacific Integrated Assessment Model (AIM/Enduse) framework. It considers the role of the renewable energy technologies as well as some emerging GHG-mitigating technologies, e.g. carbon capture and storage (CCS) in power generation, and GHG reduction in the country, and found that the power sector will play a major role in CO2 emission reduction. Under the carbon tax scenarios, most of the CO2 emission reduction (over 70%) will come from the power sector. The results also indicate the very significant potential for CO2 emission reduction through a significant change in the transport system of the country by shifting from low-occupancy personal modes of transport to electrified MRTS and railways.Publication Embargo Analytic hierarchy process for selection of ERP software for manufacturing companies(SAGE Publications, 2008-10) Perera, H. S. C; Costa, W. K. REnterprise Resource Planning (ERP) systems are popular as an IT enabled tool, which integrates different functional areas of business. ERP systems are implemented as a total business solution that supports major functionalities of business. However, many of the implementations are not success stories. Most post implementation problems are due to the inappropriate selection of systems. This paper describes multi-criteria decision model using Analytic Hierarchy Process for the selection of ERP systems for manufacturing companies. First, ERP evaluation criteria are developed by using past literature and through a questionnaire distributed among Sri Lankan manufacturing companies. Seven major criteria are identified and under each criterion several sub-criteria are identified. Selection of the best suited ERP system leads to a multi-criteria decision making problem as ERP systems should be evaluated based upon many criteria. Using the identified main and sub criteria, an Analytic Hierarchy Process (AHP) model is developed for ranking the ERP software. An example of a case is presented to show the actual implementation of AHP model. Expert Choice software is used to solve this AHP model.Publication Embargo Design and control of a high performance SCARA type robotic arm with rotary hydraulic actuators(IEEE, 2009-05-03) Liyanage, M. H; Krouglicof, N; Gosine, RThis study proposes a selective compliant assembly robotic arm (SCARA) with two revolute joints for poultry deboning. The joints of the arm are based on two high performance rotary type hydraulic actuators. These actuators are operated by servo valves, which control hydraulic fluid flow and direction. A PID based independent joint control system is considered for controlling the position of each joint. The system was modelled using the MATLAB-SIMULINK toolbox. The simulation results show that the arm was capable of covering a work envelope of 0.9 m times 0.9 m, reaching controlled velocities of up to 7.5 m/s with an average of 5.8 m/s. Obtaining such high speeds and torques would be a difficult task with electrical actuators of the capacity as the hydraulic counterparts considered here.Publication Embargo Factors affecting CO2 emission from the power sector of selected countries in Asia and the Pacific(Elsevier, 2009-06-01) Shrestha, R. M; Anandarajah, G; Liyanage, M. HThis study analyzes the key factors behind the CO2 emissions from the power sector in fifteen selected countries in Asia and the Pacific using the Log-Mean Divisia Index method of decomposition. The roles of changes in economic output, electricity intensity of the economy, fuel intensity of power generation and generation structure are examined in the evolution of CO2 emission from the power sector of the selected countries during 1980–2004. The study shows that the economic growth was the dominant factor behind the increase in CO2 emission in ten of the selected countries (i.e., Australia, China, India, Japan, Malaysia, Pakistan, South Korea, Singapore, Thailand and Vietnam, while the increasing electricity intensity of the economy was the main factor in three countries (Bangladesh, Indonesia and Philippines). Structural changes in power generation were found to be the main contributor to changes in the CO2 emission in the case of Sri Lanka and New Zealand.Publication Embargo Impact of TQM and technology management on operations performance(IUP Publications, 2010-08-01) Kuruppuarachchi, D; Perera, H. S. CThis paper examines the impact of Total Quality Management (TQM) and technology management practices on operations performance of manufacturing organizations. This study contributes to the understanding of the co-alignment between TQM and technology management by bridging the gap between the two areas which are often addressed separately. The study also examines the impact of the two practices: TQM and technology management on operations performance which have been considered as the primary sources of competitive advantage. The required data was drawn from 44 Sri Lankan manufacturing organizations and analyzed using the Structural Equation Modeling (SEM) technique followed by a detailed path analysis. The study findings indicate that TQM shows a positive predictive power against operations performance, while technology management has no significant direct relationship on operations performance simultaneously with TQM. The findings also reveal a strong interrelationship between TQM and technology management practices, which shows that the organizations with high TQM, also follow technology management practices in a better way. Along with these relationships, both TQM and technology management have interrelationships among their own components as well.Publication Embargo High speed electro-hydraulic actuator for a scara type robotic arm(IEEE, 2010-10-18) Liyanage, M. H; Krouglicof, N; Gosine, RThis study details the development of a high performance servo-hydraulic actuator for a Selective Compliant Assembly Robotic Arm (SCARA). The arm is intended for high speed food processing applications; specifically on-line poultry deboning. The system is mathematically modeled and simulated. Based on the simulation results, the hydraulic actuators are sized for optimal performance. A prototype actuator is subsequently designed, manufactured and experimentally evaluated. The tests results demonstrate that the prototype actuator is capable of producing unprecedented torques and associated accelerations relative to its size and mass. Comparable performance is not feasible with contemporary electrical actuators of similar size.Publication Open Access Lean manufacturing: A case study of a Sri Lankan manufacturing organization(AMDISA Secretariat, 2011-01-01) Kulasooriya, D. M. A; Perera, H. S. CToyota Production System (TPS) is a buzzword today in manufacturing circles. It is known as a flexi and cost-effective production model all over the world. TPS was conceptualized by Taiichi Ohno at Toyota Motor Company in 1950s (Motwani, 2003). In fact, TPS is the result of a series of best practices, which have been tested at Toyota Motor Corporation over the several decades. The goal of implementing TPS in an organization “... is to increase productivity, reduce lead-times and costs, improve quality etc.”(Sriparavastu and Gupta, 1997; Sánchez and Pérez, 2001).-Kasul and Motwani (1997) in their study find that companies that employ TPS have benefits such as “reduced lead times, just-in-time management, decreased costs, levelled production, continuous flow production, increased job satisfaction for employees, higher productivity, lower inventories, and higher quality levels.” Japanese companies have been …