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Restoration of koggala lagoon: Modelling approach in evaluating lagoon water budget and flow characteristics

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Journal of Environmental Sciences 2010年第6期22卷 813-819页

作者： Gayan Lakendra Gunaratne Norio Tanaka Prasanna Amarasekara Tilak Priyadarshana jagath Manatunge Institute for Environmental Science and Technology Graduate School of Science and EngineeringSaitama University Faculty of Fisheries and Marine Sciences & Technology University of Ruhuna Department of Civil Engineering Faculty of EngineeringUniversity of Moratuwa

Groyne system modification is described related to restoration efforts to koggaia lagoon, Sri *** large-scale unplanned sand removal at the lagoon mouth shifted the formation of sand bar towards the lagoon and made adverse effects on its ecosystem. After the removal of the natural sand bar, groyne system was constructed to avoid sand deposition in the lagoon and to protect the highway bridge （across the lagoon outlet channel） from the wave attack. The existing groyne system resulted the lagoon mouth being permanently open to sea which in turn led to many environmental problems. Groyne system modification is proposed in this study to reduce the sea water *** budget and two-dimensional depth averaged hydrodynamic model were developed for understanding the hydrologic and flow characteristics of the lagoon. Numerical experiments was performed at lagoon mouth area for two cases：（1） existing condition and （2） proposed rubble mound groyne system condition. Comparison of results was obtained for both cases to describe flow pattern at lagoon mouth. Results further showed, the width should be reduced to a maximum of 40 m. Proposed mouth width （40 m） pushed the salting factor towards 0.5 from 0.68. Salting factor reduction with the groyne modification may result a predominant influence of fresh water which may in turn lead lagoon to a fresh water ecosystem.

关键词： koggala lagoon hydrodynamic modelling lagoon hydrology

Grappling with COVID-19 by imposing and lifting nonpharmaceutical interventions in Sri Lanka: A modeling perspective

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Infectious Disease Modelling 2021年第1期6卷 820-831页

作者： Mahesh Jayaweera Chamath Dannangoda Dilum Dilshan Janith Dissanayake Hasini Perera jagath Manatunge Buddhika Gunawardana Department of Civil Engineering University of MoratuwaSri Lanka Department of Physics and Astronomy University of Texas at Rio Grande ValleyBrownsvilleTX78520USA Department of Civil&Environmental Engineering College of EngineeringSeoul National University1Gwanak-roGwanak-guSeoul08826Republic of Korea Department of Forestry and Environmental Science University of Sri JayewardenepuraSri Lanka

The imposition and lifting of non-pharmaceutical interventions(NPIs)to avert the COVID-19 pandemic have gained popularity worldwide and will continue to be enforced until herd immunity is *** developed a linear regression model to ascertain the nexus between the time-varying reproduction number averaged over a time window of six days(R_(ts))and seven NPIs:contact tracing,quarantine efforts,social distancing and health checks,hand hygiene,wearing of facemasks,lockdown and isolation,and health-related *** analysis suggests that the second wave that emerged in Sri Lanka in early October 2020 continued despite numerous *** model indicates that the most effective single NPI was lockdown and ***,the least effective individual NPIs were hand hygiene and wearing of *** model also demonstrates that to mitigate the second wave to a satisfactory level(R_(ts)kdown&isolation with health-related supports(%of improvement was 31.92 against the base case).As such,many health authorities worldwide can use this model to successfully strategize the imposition and lifting of NPIs for averting the COVID-19 pandemic.

关键词： Contact tracing Isolation Lockdown Modeling Reproduction number

Developing an Integrated Complementary Relationship for Estimating Evapotranspiration

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Natural Resources 2018年第4期9卷 89-109页

作者： Homin kim jagath J. kaluarachchi Utah Water Research Laboratory Utah State University Logan UT USA College of Engineering Utah State University Logan UT USA

The complementary relationship for estimating evapotranspiration (ET) is a simple approach requiring only commonly available meteorological data;however, most complementary relationship models decrease in predictive power with increasing aridity. In this study, a previously developed Granger and Gray (GG) model by using Budyko framework is further improved to estimate ET under a variety of climatic conditions. This updated GG model, GG-NDVI, includes Normalized Difference Vegetation Index (NDVI), precipitation, and potential evapotranspiration based on the Budyko framework. The Budyko framework is consistent with the complementary relationship and performs well under dry conditions. We validated the GG-NDVI model under operational conditions with the commonly used remote sensing-based Operational Simplified Surface Energy Balance (SSEBop) model at 60 Eddy Covariance AmeriFlux sites located in the USA. Results showed that the Root Mean Square Error (RMSE) for GG-NDVI ranged between 15 and 20 mm/month, which is lower than for SSEBop every year. Although the magnitude of agreement seems to vary from site to site and from season to season, the occurrences of RMSE less than 20 mm/month with the proposed model are more frequent than with SSEBop in both dry and wet sites. Another finding is that the assumption of symmetric complementary relationship is a deficiency in GG-NDVI that may introduce an inherent limitation under certain conditions. We proposed a nonlinear correction function that was incorporated into GG-NDVI to overcome this limitation. As a result, the proposed model produced much lower RMSE values, along with lower RMSE across more sites, as compared to SSEBop.

关键词： Evapotranspiration NDVI Complementary Relationship SSEBop

Comparison between Differently Synthesized Hydroxyapatite Composites for Orthopedic Applications

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Journal of Materials Science and Chemical Engineering 2019年第5期7卷 16-28页

作者： kalinga Hapuhinna Rajitha Gunaratne jagath Pitawala Department of Engineering Technology Faculty of Technology University of Sri Jayewardenepura Nugegoda Sri Lanka Department of Science & Technology Faculty of Science & Technology Uva Wellassa University Badulla Sri Lanka

Study carried to find out chemical and structural suitability of newly synthesized Eppawala hydroxyapatite composite varieties as bone cement, by comparing and contrasting them with human bone as well as commercially available bone cement, which is currently used in orthopedic surgeries. Commercially available methyl methacrylate (MMA) monomer used to reinforce solid state sintered and sol gel synthesized hydroxyapatite ceramic to prepare its composites as bone cements and their physical and chemical properties including composition, crystallinity, presence of functional groups, thermal stability, surface morphology, and microstructural features were examined compared to human bone. Results show there is a close similarity between synthesized products and human bone while credenting high thermal stability, good crystalline, and porous properties than the commercial product. Finally, study concluded newly synthesized composites can be applied directly as a substitution for commercial bone cement while having different properties from each other.

关键词： Human Bone Hydroxyapatite Methyl Methacrylate Orthopedics

Mobile Agent Platform and Naming Scheme of Agents

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Journal of Shanghai University(English Edition) 2004年第2期8卷 177-179页

作者： Sudin SHRESTHA 徐拾义 jagath RATNAYEkE School of Computer Engineering and Science

Mobile agent technology has drawn a tremendous amount of attention from researchers in distributed computing recently as it promises to provide an elegant and efficient way of solving complex distributed problems, as well as offering a new approach to human-computer-interaction. In mobile agent systems, the mobile agent travels autonomously from one computer to another within the agent enabled networks, executes itself in the agent execution environment, collects useful information and makes its own decision or behalf of its owner. This mobility nature of mobile agent demands its unique name in the whole network otherwise it gets lost or conflicts with other mobile agent having same name. This paper proposes a naming scheme which promises a unique name for a mobile agent within that network. key words mobile agent - mobile agent platform - naming scheme

关键词： mobile agent mobile agent platform naming scheme

Advances in Information Provision from Wireless Sensor Networks for Irrigated Crops

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Wireless Sensor Network 2018年第4期10卷 71-92页

作者： jagath C. Ekanayake Carolyn B. Hedley Landcare Research—Manaaki Whenua Lincoln New Zealand

Current advances in connected sensor technologies for near real-time environmental monitoring are transforming the quality of information provision to land managers. This “Third Industrial Revolution” that connects digital sensor data analytics with adaptive services aims to transform data processing for timely decision support. The information is needed to improve irrigation scheduling, because global demand for food relies heavily on irrigation and global freshwater resources are diminishing. Previously, practitioners used visual indicators, infrequent measurements or predictive water balance models to estimate irrigation schedules. Visual indicators and infrequent measurements are approximate, and predictive models require many inputs so that likely cumulative errors cause inaccuracies in scheduling. In contrast, wireless sensor networks enable near real-time continuous measurement of soil moisture at targeted positions providing the site-specific information required for precision irrigation scheduling and efficient freshwater management. This paper describes and compares the structure, build and implementation of Crossbow, DigiMesh, and LoRa systems to deliver information on spatio-temporal soil water status and crop stress to practitioners over smart phones and webpages to improve management of irrigated land. Our study found that the newer LoRA system has advantages over the other systems, especially on flat land, with furthest node range of >10 km and advanced communication protocols that can penetrate dense vegetation. The mesh networking of the DigiMesh and Crossbow systems was preferred in hilly terrain to communicate around hills, and allows easy expansion of the network. The Crossbow system is simpler to install but presents difficulties for third party sensor integration. All systems allowed a step change in our ability to track dynamic changes in soil hydraulic properties and crop stress, to improve irrigation water use efficiency.

关键词： Micaz ZigBee DigiMesh LoRa Irrigation

Review on Non-thermal Technologies for the Preservation of Fruit Juices

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Journal of Agricultural Science and Technology(B) 2019年第6期9卷 365-372页

作者： Erandya Jayawardena Mihiri Vanniarachchi jagath Wansapala Department of Food Science and Technology University of Sri JayewardenepuraGangodawilaNugegoda 10250Sri Lanka

Liquid food industries use different preservation methods to extend the shelf life of products by reducing both enzymatic and microorganism *** non-thermal pasteurization techniques are applied in order to avoid thermal processes maintaining the microbial safety and quality of liquid ***-thermal preservation technologies used in the liquid food industry include high-pressure processing(HPP),pulsed electric field(PEF),ultraviolet light(UV-C)and ultra-sonication(US).HPP is a method to target specific organisms by applying a pressure range of 100-1,000 *** uses short pulses of a strong electric field applied to a flowing liquid food which affects the whole cell membrane of the ***-C treatment at 253.7 nm has been proven to be appropriate for maintaining liquid quality and minimal deterioration of *** is applied to liquid foods in a lower frequency range of 20-100 kHz and a higher sound intensity of 10-1,000 W/cm2 to the breakdown of *** to scientific literature,those methods have been applied to fruit juices like orange,apple,pear,coconut water,*** of the non-thermal methods achieved the Food and Drug Administration(FDA)requirement of a 5-log reduction of microorganisms without deteriorating the sensory and nutritional attributes of fruit *** of these methods have already been commercialized and others are still in a pilot *** study gives a comprehensive overview of published literature regarding the potential for using non-thermal pasteurization methods to extend the shelf life of different fruit juices with minimal deterioration of nutritional and sensory quality.

关键词： Non-thermal pasteurization high-pressure process pulsed electric field UV-C light ultrasound