Faculty of Engineering
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Publication Open Access Postharvest ripening and respiration of chili(University Of Ruhuna, 2004) Chaturani, G. D. G; Wilson, S; Perera, S. V. T; Hettiarachchi, M. PEffect o f exogenous ethylene application on postharvest ripening and respiratory pattern o f chilli (Capsicum annum Var.MI-2) harvested at different stages o f maturity was examined. Chillies harvested at mature green and colour break stages were used fo r the ripening study. Pods were allowed to ripen at ambient conditions (32 ± 2 °C and 37% RH) with 0, 100, 200, 300, and 400ppm ethylene concentrations. Observations were made on colour development and weight o f red ripe pods during storage period. Ethylene treatment had no significant effect on colour development o f chilli harvested at both stages o f maturity. Fruits harvested at different stages o f maturity ranging from light green to fu ll red were usedfor the respiration study at 12.2 °C and 83 % RH in a closed system. Respiration rates o f chilli from light green to fu ll red stage ranged between 12.7-24.2 mgCO/kg/h. The rate o f respiration was low at light green stage and increased with maturity reaching a peak (24.2 mgCO/kg/h) at colour break stage. Respiration rate decreased with fru it ripening and increased with development o f full red colour. The internal ethylene concentration o f pods was ranged between 3.2-4.3 ppm. However, there was no ethylene peak observed with the maturity.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 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 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 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 Iron and manganese removal from textile effluents in anaerobic attached-growth bioreactor filled with coirfibres(IWA Publishing, 2007) Jayaweera, M. W; Gomes, P. I. A; Wijeyekoon, S. Lt A laboratory scale study on Fe and Mn removal in upflow anaerobic bioreactor of a working volume of 20 L with coir fibre as the filter medium was investigated for a period of 312 days. The maximum Fe and Mn levels considered were 10 and 5 mg/L respectively, which are the typical average values of textile effluents subsequent to the primary and secondary treatments. Ten sub-experimental runs were conducted with varying HRTs (5 days to 1 day), ratios of COD:SO22 4 (20 to 3.5), Fe levels (0.005 to 10 mg/L) and Mn levels (0 to 5 mg/L). COD:SO22 4 of 3.5 was identified as the optimum point at which sulphate reducing bacteria (SRBs) out competed methane producing bacteria (MPBs) and further reduction of this ratio caused total and/or significant inhibition of MPBs, thus building sulphate reducing conditions. The effluent contained Fe and Mn below the permissible levels (1.6 and 1.1 mg/L for Fe and Mn, respectively) stipulated by US National Pollution Discharge Elimination System (NPDES) for inland surface waters at HRTs higher than 3 days. Results of the mass balance showed more Fe accumulation (60%) in sediments whereas 27% in the filter media. An opposite observation was noticed for MnPublication Embargo Spatial and temporal heterogeneity of Eragrostis curvula in the downstream flood meadow of a regulated river(EDP Sciences, 2009) Gomes, P. I. A; Asaeda, TWe studied the spatiotemporal trends of Eragrostis curvula (Schrad.) Nees in a flood meadow of a regulated river. The response variables, including the abundance of colonies, colony sizes, flowering spikes, biomass and root structure were checked against a set of environmental variables. These variables included distance from the river, substrate conditions (stony to sandy), soil nutrients (total nitrogen, phosphorous and calcium) and soil moisture. Relationships were evidenced using redundancy analysis. Response variables were found to be distinctive and based on substrate conditions (i.e. stony or sandy). The variables ‘distance from the river’ and ‘soil phosphorous’ contributed significantly to the overall variance. Stony habitats were observed to have lower soil nutrient levels and were characterised by monospecific stands of E. curvula, while the high nutrient levels of sandy habitats promoted heterogeneous herbaceous vegetation growth. Primary production, especially belowground, was measured to be significantly higher (t-test, P<0.05) in stony habitats. Spatiotemporal trends suggested that, irrespective of the number of colonies, E. curvula demonstrated significant levels of adaptation to micro-environments through biomass allocation and the morphological plasticity of its roots. The study results suggest that river regulation and the subsequent reduction in the frequency of inundation, in addition to the reduction of nutrients and fine sediment supply downstream, give a competitive edge to E. curvula over other herbaceous species.Publication Embargo Phycoremediation of Chromium (VI) by Nitella and impact of calcium encrustation(Elsevier, 2009-07-30) Gomes, P. I. A; Asaeda, TThis article discusses the applicability of the Charophyte, Nitella pseudoflabellata in the remediation of Cr (VI) contaminated waters at different calcifying potentials. Its growth was found to be positively correlated with Ca in water (CaW), but marginally significant in the presence of Cr (VI) in water (CrW). High CaW resulted in calcite encrustation on the plant cell wall. CaW was found to be aiding Cr (VI) fixation in the long run, as this correlated positively with both CaW and CrW. However, Ca interfered with passive Cr (VI) accumulation in live plant matter at low CrW concentrations (≤0.2 mg/L). Biosorption by dead plant matter seemed to be the major mechanism as the dead plant organs contained >1 mg/g Cr dry weight of plant. Cr (VI) concentrations greater than 0.4 mg/L were too toxic, showing maximum quantum efficiency of PSII photochemistry (Fv/Fm) values < 0.63. The opposite was noticed (Fv/Fm > 0.76) when Cr (VI) was less than 0.2 mg/L. Elongation curve patterns based on shoot lengths showed similar scenarios. In all cases high CaW units with calcite encrustation found to be least affected by Cr (VI) toxicity. Optimum remediation was obtained using a combination of high Ca and Cr (VI) in the case of passive (short-term) operation and low Ca and Cr (VI) for active (long-term) operation. Under the passive scenario, plants accumulated above 1.2 mg/g Cr dry weight whereas in the active case, accumulation was 0.8 mg/g Cr dry weight. We conclude that Nitella-mediated Cr (VI) remediation is a promising technique within the range and conditions investigated.Publication Embargo Free route air traffic flow manager(IEEE, 2005-12-11) Abeysooriya, M; Kulasekere, E. CAs the world moves towards the era of globalization and as the business world continues to revolutionize, meeting the expectations of a timely and safe air transportation system has become major challenge to the field of aviation. Most of the existing air traffic control systems primarily focus on generating pre-defined routes for aircrafts based on the 'fixed route model'. But with the advancement of technologies in the field of aviation an effective and practical mechanism called 'free route modeling' has been introduced. The few test beds that exist worldwide based on this concept, have been implemented for certain specific airspaces eliminating the possibility of using this strategy at any location worldwide. This paper presents the design and implementation of the 'free route air traffic flow manager' project which proposes a framework which can be used as a generic tool to over come this limitation. This tool will allow the user to dynamically create a free route modeling system for a certain airspace by configuring a 3D airspace according to the given requirements for that airspace. The dynamically developed free route modeling system will facilitate the functionalities of generating the initial free route for an aircraft & provide dynamic re- planning for the configured air space when a conflicting scenario is reported.Publication Embargo Distributed Wireless CSMA/CA based Unified Navigation Solution(IEEE, 2006-12-15) Samarakoon, S. M. D. D; Silva, A. P. M; Samaraweera, S. M. D. W; Fernando, T. G. A; Kulasekere, E. CThis research proposes a multiple access protocol known as the Distributed Wireless CSMA/CA (DWCC). This protocol is optimized for a distributed wireless communication network where the node availability and behavior are both uncertain and unpredictable. An application based on a distributed communication network formed using inter vessels communication at deep sea is used to illustrate the salient features of the proposed protocol. A method is outlined on how the proposed new protocol can be applied to extend radar vision at each vessel in the presence of radar jamming and/or communication node failure at mid sea. That is, the DWCC protocol is used to gather information from all vessels to construct a cumulative radar map at any node and thus extending the radar vision beyond the display capability of a single node.