Faculty of Science

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/213

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The McDonald generalized Beta-Binomial distribution
(University of Peradeniya, 2013) Chandrabose, Manoj; Wijekoon, Pushpa; Yapa, Roshan D.
The binomial outcome data are widely encountered in many real world applications. The Binomial distribution often fails to model the binomial outcomes since the variance of the observed binomial outcome data exceeds the nominal Binomial distribution variance, a phenomenon known as overdispersion. One way of handling overdis- persion is modeling the success probability of the Binomial distribution using a continuous distribution defined on the standard unit interval. The resultant general class of univariate discrete distributions is known as the class of Binomial mixture distributions. The Beta-Binomial (BB) distribution is a prominent member of this class of distributions. The Kumaraswamy-Binomial (KB) distribution is another recent member of this class. In this paper we focus the emphasis on the McDonald’s Generalized Beta distribution of the first kind as the mixing distribu- tion and introduce a new Binomial mixture distribution called the McDonald Generalized Beta-Binomial distribu- tion(McGBB). Some theoretical properties of McGBB are discussed. The parameters of the McGBB distribution are estimated via maximum likelihood estimation technique. A real world dataset is modeled by using the new McGBB mixture distribution, and it is shown that this model gives better fit than its nested models. Finally, an ex- tended simulation study is presented to compare the McGBB distribution with its nested distributions in handling overdispersed binomial outcome data.
Improvement of the preliminary test estimator when stochastic restrictions are available in linear regression model
(University of Peradeniya,, 2013) Arumairajan, Sivarajah; Wijekoon, Pushpakanthi
Ridge type estimators are used to estimate regression parameters in a multiple linear regression model when multi- colinearity exists among predictor variables. When different estimators are available, preliminary test estimation proce- dure is adopted to select a suitable estimator. In this paper, two ridge estimators, the Stochastic Restricted Liu Estimator and Liu Estimator are combined to define a new preliminary test estimator, namely the Preliminary Test Stochastic Re- stricted Liu Estimator (PTSRLE). The stochastic properties of the proposed estimator are derived, and the performance of PTSRLE is compared with SRLE in the sense of mean square error matrix (MSEM) and scalar mean square error (SMSE) for the two cases in which the stochastic restrictions are correct and not correct. Moreover the SMSE of PTSRLE based on Wald (WA), Likelihood Ratio (LR) and Lagrangian Multiplier (LM) tests are derived, and the per- formance of PTSRLE is compared using WA, LR and LM tests as a function of the shrinkage parameter d with respect to the SMSE. Finally a numerical example is given to illustrate some of the theoretical findings.
Improvement of ridge estimator when stochastic restrictions are available in the linear regression model
(University of Peradeniya, 2014) Arumairajan, Sivarajah; Wijekoon, Pushpakanthi
In this paper we propose another ridge type estimator, namely Stochastic Restricted Ordinary Ridge Estimator (SRORE) in the multiple linear regression model when the stochastic restrictions are available in addition to the sample information and when the explanatory variables are multicollinear. Necessary and sufficient conditions for the superiority of the Stochastic Restricted Ordinary Ridge Estimator over the Mixed Estimator (ME), Ridge Estimator (RE) and Stochastic Mixed Ridge Estimator (SMRE) are obtained by using the Mean Square Error Matrix (MSEM) criterion. Finally the theoretical findings of the proposed estimator are illustrated by using a numerical example and a Monte Carlo simulation.
Orientation of easy axis of ferromagnetic films as explained by third order perturbed Heisenberg Hamiltonian
(University of Peradeniya, 2013) Samarasekara, P.; Rajakaruna, Prabhani
The third order perturbed Heisenberg Hamiltonian has been applied to explain the magnetic easy axis orientation. Ferromagnetic CoPt/AlN multilayer thin films with number of layers N=11, 16 and 21synthesized on fused quartz substrates using dc magnetron sputtering technique have been employed as experimental data. According to experimental research performed by some other researchers, easy axis of these fcc structured ferromagnetic films is oriented in the plane of the film above one particular temperature. Average value of out of plane spin component was plotted against temperature in order to determine the spin reorientation temperature. The spin reorientation temperature was highly sensitive to 2nd order magnetic anisotropy constant.
Third order perturbed Heisenberg Hamiltonian of spinel ferrite ultra-thin films
(2011) Samarasekara, P.; Mendoza, Wiliam, A.
The classical Heisenberg Hamiltonian equation of spinel ferrite ultra-thin films will be solved for third order perturbation. When second order anisotropy constant do not vary within the film of N=2, the film behaves as an oriented film. But the film of N=3 does not behave as an oriented film even for invariant second order anisotropy. Also the second and third order perturbations become zero in perpendicular and in plane directions, indicating that films behave as oriented films. For N-2 film, nearest maximum and minimum can be observed at 45 0 and 135 0 , respectively. For N=3, the first nearest maximum and minimum are observed at 470 and 1370 , respectively. In both cases, the angle between easy and hard direction is 900 , and the energy at hard or easy directions does not vary with angle. The 3- D plot of total energy versus angle and stress induced anisotropy indicates some energy minimums. Fourth order anisotropy slightly destroys the smoothness of the energy curve with N=3.
Relationship between demagnetization factor and energy of thick ferromagnetic films
(University of Peradeniya,, 2012) Samarasekara, P.
The variation of energy of ferromagnetic thick films of 10000 layers with demagnetization factor will be described in this report using second order perturbed Heisenberg Hamiltonian. Under the influence of demagnetization factor given by, the sc(001) film with 10000 layers can be easily oriented in 0.6 radians direction for the values of energy parameters used in this report. Easy direction of thick fcc(001) film with 10000 layers was determined as 0.66 radians, when the demagnetization factor is given by. The energy of sc(001)thick film is larger than that of fcc(001) thick film. But the energy curve of fcc(001) thick film is smoother than that of sc(001). Keywords: Thick magnetic films, demagnetization factor, Heisenberg Hamiltonian
In plane oriented strontium ferrite thin films described by spin reorientation
(University of Peradeniya,, 2013) Samarasekara, P.; Saparamadu, Udara
For the first time, in plane orientation of magnetic easy axis of sputtered strontium hexaferrite thin films has been explained using modified Heisenberg Hamiltonian model with stress induced anisotropy term. The variation of average value of in plane spin component with temperature was plotted in order to determine the temperature at which easy axis is oriented in the plane of the strontium ferrite film. The average value of in plane spin component in this 2-D model reaches zero at one particular temperature. This particular temperature obtained using our theoretical model agrees with the experimental value of the temperature of rf sputtered polycrystalline strontium ferrite thin films deposited on polycrystalline Al2O3 substrates (500°C). This spin reorientation temperature solely depends on the values of energy parameters used in our modified Heisenberg Hamiltonian equation
Determination of energy of trhick spinel ferrite films using Heisenberg Hamiltonian with second order perturbation
(University of Peradeniya, 2010) Samarasekara, P.
The energy of thick spinel ferrite films have been calculated by means of classical Heisenberg Hamiltonian. In all cases, maximum energy in ferrite thick films is larger than that of ferromagnetic thick films with 2nd order perturbation. The energy required to rotate from easy direction to hard direction is very small near N=90. Also energy of ferrite thick films with 2nd order perturbation is lager than that of oriented ferrite films. The first energy maximum and minimum can be observed at θ=34.40 and 103.20, respectively. Especially the effect of stress induced anisotropy on energy was investigated, and the film can be easily oriented in some certain directions by applying certain stresses
Gas sensing properties of tungston oxide thin films in Methane and Nitric oxide gases
(University of Peradeniya,, 2009) Samarasekara, P.
Tungsten oxide (WO3 ) thin films, which were synthesized between micro-patterned gold electrodes and annealed at 500 o C in air for 2 hours, were developed as methane (CH4 ) and nitric oxide (NO) gas sensors. The as-deposited films exhibited an amorphous structure and annealed films indicated crystalline WO3 with the average grain size of 40 nm. The structure of films was determined by means of X-ray diffraction (XRD) methods. The highest sensitivity for 10 ppm NO gas in air at 255 o C was 0.9 and 1.6 for thin and thick WO3 films, respectively. The respond and recovery times of thinner films were faster than thicker films. The sensitivity was also measured for high concentration level of methane gas for comparison. The highest methane gas sensitivity was 6.5 for 6% methane in air at 355 o C. The origin of this gas sensitivity can be explained using grain boundary control model
Determination of magnetic properties of cobolt films using second order perturbed Heisenberg Hamiltonian
(University of Peradeniya, 2012) Samarasekara, P.; Ariyaratne, Amila D.
The magnetic properties of hexagonal closed packed structured ferromagnetic cobalt films were investigated by means of second order perturbed Heisenberg Hamiltonian. First the number of nearest neighbors and the constants arisen from the partial summation of the dipole interactions of the structure of cobalt were calculated using some special algorithms. Minimization of the energy difference between the easy and hard direction of a memory device is very important. When the energy difference between the easy and hard directions is significantly small, the magnetic moments in a memory device can be quickly rotated between easy and hard directions under the influence of a small magnetic field. The thickness of a cobalt film corresponding to this minimum energy difference calculated using this theoretical model agrees with some experimental data of cobalt-based magnetic memory devices
A user-friendly java-ased statistical tool to analyse the segregation data of crosses in genetics and breeding
(University of Peradeniya, 2011-11-24) Liyanaarachchi, L. A. P. N; Yapa, Y. P. R. D; Sooryapathirana, S.D.S.S.
Genetic and breeding studies are characterised by making crosses between selected parental organisms and establishing segregating populations such as F2, back crosses, test crosses, pseudo test crosses and recombinant inbred lines followed by detailed observations and statistical analyses of phenotypic data for traits of interest. The phenotypic data are often considered as ratios (e.g. 26 short: 37 tall in plants) for both major gene and poly gene controlled traits. In genetics, there are standard ratios for genetic segregations and using standard ratios as expected ratios. A goodness of fit test for observed phenotypic ratios is also conducted. When a geneticist or a breeder comes up with a ratio for observed phenotypic data, multiple comparisons could be made against many standard genetic segregation ratios to select the highest significant match for biological interpretation and practical uses. The multiple comparisons under different probability levels are time consuming and demand considerable expertise in non- parametric statistics. Therefore, an attempt was made to design a user-friendly Java- based statistical tool to analyse segregation data from crosses in genetics and breeding. This statistical tool can be used by geneticists and breeders with limited statistical knowledge to get most approximate ratios for observed phenotypic crosses. A statistical tool was developed by using Java programming language in NetBeans IDE 6.8. The population size in number of individuals, standard ratio and observed ratio for phenotypic data have to be entered and highest matching ratio and goodness of fit for other possible standard ratios can be obtained as the output. The tool was tested and validated by using already published data from genetic crosses. The developed statistical tool is user-friendly and quick in finding the significant standard ratios in genetic and breeding studies. This is useful for purposes of genetic research, breeding, and teaching genetics to undergraduate, postgraduate and Advanced Level Biology students.
Structure optimization and IR frequency interpretation of Fe6(OH)1s(H20)6 Nano particles by OFT calculations
(University of Peradeniya, 2024-11-24) Jayarathna, Lakmal; Bandara, Athula; Vithanaqe, M; Weerasooriya, R
y-Fe203 nanopratciles were syntheised by the co-precipitation method and these particles are in 5-20 nm range in size. Plausible molecular structures (Figure 1) of Y - Fe203 were examined by density functional theory (DFT) using the cluster modelling method. Cluster configurations and IR frequency calculations of Fe6(OH)18(H20)6 were performed using the DFT hybride 83L YP function with 6-31 G (d, p) basic set. The average bond lengths of Fe-Fe and bulk Fe-O entities as 2.93 A and 1.92 A, respectively. The calculated bond lengths are comparable with the crystallographic data. Vibrational frequency calculations and experimental data are in good agreement with the observations in the range of 900 cm' t01024 cm' (Figure 2). However, OH stretching frequencies at (1640), 3000, 3500 crn' of y -Fe203 is significantly different due to H- bonding nature.
Preparation, characterization and in-vitro release study of Ascorbic acid- Encapsulated liquid Crystal liposomes
(University of Peradeniya, 2024-11-24) Hewawarawlta, L. S; Perera, A. D. L. C; Karunaratne, D. N
The use of liquid crystals at the nano level shows some valuable applications in numerous areas. Liposome formulations are used in the medical, food and cosmetic fields after the encapsulation with bioactive ingredients. Generally, liposomes are mainly formed of phospholipids and are used as a store and vehicle for bioactive ingredients. The purpose of the present research was to formulate effective and controlled drug release liquid crystal liposomal formulations. Water soluble ascorbic acid (vitamin C) was used as the model drug and carbohydrate liquid crystal, ETAGP (2,3,4,6-tetra-o- acetyl-epiandrosteronyl-1-0-[l,-D-glucopyranoside) was used as the model liquid crystal. For comparison, conventional liposomes were formulated with phospholipids (egg yolk lecithin) and mixed liposomes with phospholipids and carbohydrate liquid crystals in different compositions. Characterization of the prepared liposomes regarding encapsulation efficiency, pH dependence, particle size analysis and in-vitro release were performed. Carbohydrate liquid crystal liposomes show some characteristics similar to conventional liposomes, such as the drug encapsulation efficiency and pH dependence, whereas the drug release rate is significantly increased in the carbohydrate liquid crystal liposomes. Interestingly, the particle size in the carbohydrate liquid crystal liposomes is in the nano range and the particle size remains the same without forming clusters for several weeks. These novel liquid crystal liposome formulations may have potential applications in encapsulation and delivery of drugs and bioactive ingredients in cosmetic formulations.
A preliminary study on the Hypoglycaemic effect of Averrhoa Carambola (Star Fruit) in rats
(University of Peradeniya, 2024-11-24) Gunasekara, L .C. A; Fernando, P. H. P; Sivakanesan, R
Diabetes mellitus (OM) is one of the five leading causes of death in the world. As estimated in 2008, around 24% of the Sri Lankan population suffer from this deadly disease. Maintenance of normoglycaemia is the key issue in managing these patients, and this is achieved by administering exogenous insulin or other hypoglycaemic agents. Averrhoa carambola (star fruit) leaves have been a part of traditional medicine used in Ayurvedic preparations to treat OM in Sri Lanka. Researchers have investigated the hypoglycaemic effects of several insoluble fiber-rich fractions (FRFs) including insoluble dietary fiber, alcohol-insoluble solid and water insoluble solid from the pomace of Acarambola. The objective of the study was to investigate the effect of Acarambola fruit pulp on blood glucose level of healthy rats. Thirty male Sprague Dawley rats weighing between 150-350 g and ten healthy female Sprague Dawley rats of the same age and weight were used in the study. The animals were caged individually at the Animal House, Faculty of Medicine and were provided with 25 g of broiler starter feed per day with ad libitum water. They were allowed to get accustomed to the experimental set up for a period of two weeks and were divided equally into the test groups (male and female), and control groups (male and female). A carambola fruit pulp was prepared by homogenising ripe fruit with a little added water in a warring blender and the resultant pulp was stored at -20°C. The animals in the test groups were then fed with the A carambola fruit pulp at a rate of 1600 mg/kg body weight for 63 days and the fasting blood glucose levels were measured each week, using an enzymatic assay method using glucose oxidase enzyme. Results were compared between A. carambola fruit pulp treated group (1600 mg/kg BW) and control group which received only the basal diet using analyses of variance and Dunnet's t-test. Treatment with A carambola fruit pulp significantly (p = 0.033) decreased blood glucose levels (mean 131.0 ~ 10.2 mg/dl) after a treatment period of 8 weeks and elevated body weight in healthy male Sprague Dawley rats compared to that of normal rats (blood glucose levels mean 153.4 ~ 11.2 mgidl). However, although there was a decrease in blood glucose level of the test group after three weeks of treatment the difference was not statistically Significant up to 7 weeks. Treatment with A carambola fruit pulp non-significantly decreased the blood glucose levels in healthy female rats after treating for 8 weeks, compared to that of control rats which could be due to hormonal changes in the female animals. This study demonstrates that the A carambola fruit pulp has a hypoglycaemic effect on mammalian systems, which need to be investigated further.
A preliminary study on bioactivities of Agave Vera - cruz leaf extract
(University of Peradeniya, 2024-11-24) Karunaratne, K. U; Ranawana, K. B; Wickramasinghe, A
Agave vera-cruz is a perennial plant with large, spine-tipped leaves and short thick stems. It belongs to the family Agavaceae. It appears to be well established in Badulla, Nuwara Eliya and Kandy districts. Fibre obtained from this plant is used to make ropes, baskets and cloths. Freshly ground leaves of Agave vera-cruz are currently used as a piscicidal agent in fishing by remote farmers in the Knuckles region. The present study is an attempt to evaluate bioactive properties of Agave vera-cruz. Antioxidant, cytotoxic and phytotoxic properties were investigated. Plant materials were collected from Wattappola in Paranapattiya area. Freeze- dried plant materials were ground into a powder and extracted into methanol (MeOH). Concentrated crude extract was subjected to bioassay. Phytotoxic activity against Lactuca sativa, cytotoxic activity against Artemia salina and antioxidant activity were evaluated. Fractionation involved the use of VLC chromatography using Merck 9385 (40-63 Jim) silica gel, gravity column chromatography using 7734 Merck silica gel (63-200 ,urn) and analytical thin layer chromatography. LD50 value for cytotoxic bioassay was 675 ppm for the MeOH extract. IC50 value for the DPPH radical assay was 62.0 ppm. IC50 value for shoot inhibition was 1000 ppm and that for root inhibition was 1800 ppm. These results show that there are some allelopathic compounds present in Agave vera-cruz.
A preliminary study on bioactivities of Agave Vera - Cruz leaf extract
(University of Peradeniya, 2011-11-24) Karunaratne, K. U; Ranawana, K. B; Wickramasinghe, A
Agave vera-cruz is a perennial plant with large, spine-tipped leaves and short thick stems. It belongs to the family Agavaceae. It appears to be well established in Badulla, Nuwara Eliya and Kandy districts. Fibre obtained from this plant is used to make ropes, baskets and cloths. Freshly ground leaves of Agave vera-cruz are currently used as a piscicidal agent in fishing by remote farmers in the Knuckles region. The present study is an attempt to evaluate bioactive properties of Agave vera-cruz. Antioxidant, cytotoxic and phytotoxic properties were investigated. Plant materials were collected from Wattappola in Paranapattiya area. Freeze- dried plant materials were ground into a powder and extracted into methanol (MeOH). Concentrated crude extract was subjected to bioassay. Phytotoxic activity against Lactuca sativa, cytotoxic activity against Artemia salina and antioxidant activity were evaluated. Fractionation involved the use of VLC chromatography using Merck 9385 (40-63 Jim) silica gel, gravity column chromatography using 7734 Merck silica gel (63-200 ,urn) and analytical thin layer chromatography. LD50 value for cytotoxic bioassay was 675 ppm for the MeOH extract. IC50 value for the DPPH radical assay was 62.0 ppm. IC50 value for shoot inhibition was 1000 ppm and that for root inhibition was 1800 ppm. These results show that there are some allelopathic compounds present in Agave vera-cruz.
PCR·SSCP Polymorphism of BMP4 Gene (Intron II) in goats in Damana and Thirukkovil Veterinary service divisions in the Ampara District of Sri Lanka
(University of Peradeniya, 2011-11-24) Lokugalappatti, L. G. S; Wijesena, H. R; Munasinghe, D. M. S; Gunawardena, D. C. A; Ariyaratne, H. B.S
Application of molecular genetic approaches for screening of economically important quantitative traits (i.e. growth and reproduction) in goats is an effective way of increasing their productivity through improved selection based on genetic markers. Single Strand Confirmation Polymorphism (SSCP) analysis is one such powerful. genetic screening method to identify the sequence variation in Polymerase Chain Reaction (PCR) amplified DNA. In the present preliminary study, we investigated genetic variation in the second intron of bone morphogenetic protein 4 (BMP4) gene, by PCR-SSCP, in local indigenous (LI) and Jamnapari crossbred (JC) goats in Damana and Thirukkovil Veterinary Service (VS) divisions in the Ampara district. Genomic DNA was extracted from a total of 103 samples (49 LI and 54 JC) collected from 15 farms located in the two VS divisions and subjected to PCR-SSCP analysis. Polymorphism was detected in both LI and JC goats of the study area and five different conformational patterns were identified (A through E). Three conformational patterns (A, B and C) were found in both LI and JC animals. Patterns D and E were unique to LI animals, indicating the benefit of searching for more genetic markers. Calculated total frequencies of patterns A, B, C, D and E as revealed by PCR-SSCP were 58.25%, 14.56%, 5.83%, 11.65% and 9.71 % respectively. In general, pattern A was predominantly found in both LI (40.43%) and JC (73.21%) whereas pattern C was found to be at lowest frequency in both groups. Pattern D observed in LI goats may have some association with phenotype and growth of the animals as we observed similar external characters in all the animals possessing pattern D. Gene sequencing of the five conformational patterns observed are being pursued to identify the genotypes and the alleles present.
Migrant Wife and Househusband: Transformation of Household Gender Roles with Female Migration
(University of Peradeniya, 2011-11-24) Pinnawala, M
Traditionally the woman's place of "work" has been confined to the so-called private sphere, namely, the household. In the household, she was expected to perform traditional womens' work such as looking after the children, washing, cooking, etc. The husband was the provider of the family and his tasks were almost exclusively in the public sphere. Many women today have become providers, sometimes even as sole income earners of the family. One modern context in which this traditional division of gender roles comes into question is when woman become independent migrants requiring husbands to takeover traditional household tasks. Research shows that this has often resulted in displacing the husband from the traditional role of the sole decision maker in migrant households. These changes are challenging the traditional pattern of male-dominated household organization and have resulted in emergence of a new phenomenon described as migrant-wife or househusband. This paper examines how the changing of the traditional role of the wife affects the husband's traditional role in the households of Sri Lankan women who are working in the Middle East as housemaids. ' The study was conducted in a migrant source community in the district of Kurunagala in the North Western Province of Sri Lanka. Ten households with husbands whose wives were abroad at the time and ten others whose wives had been abroad were selected for the study. Migration of a woman creates a functional vacuum in the household affecting its operations. The solution to this is often in the form of adjustment to the roles and status of the existing (functional) members of the household or through infusion of new members from the kinship network. When the husband takes the responsibilities of the wife it lowers the statusl social position of the husband in the eyes of the community because he is doing what is traditionally considered to be womens' work. The social position of the husband is particularly affected when he is substituting for his wife doing domestic chores and there is another person, proxy and female, managing the funds remitted by the wife. There are also some changes in the gender division of labour not only in "during migration household", but also in "post migration households". It was found that there was an increase in the number of husbands sharing work in the majority of households of returned migrants. The study showed that while the wife is abroad many husbands take up household activities traditionally performed by the wife. Although this happens out of necessity, the majority of husbands were found to be happy with this arrangement as they felt that they should contribute to running of the family as the wife is now the provider. Yet at times, they also felt that their changing gender roles negatively affected their social position (and male ego). However, household relationships led to conflicts when there was a proxy coming from outside, for example, a relative, managing the finances of the wife, as husbands do not feel comfortable with another person having control over the family budget. The social position of the husband also becomes a major issue when the proxy manager is a woman.
Low Carbon cooling solutions for the apparel industry: open cycle desiccant cooling systems
(University of Peradeniya, 2011-11-24) Bakmeedeniya, L. U; Rajapaksha, L
Use of mechanical ventilation and air conditioning is becoming more prevalent in commercial and industrial sectors due to warm and humid outdoor conditions in most parts of the country. Such change in the use of energy for comfort is further supported by the requirements for clean air in working environments specified in relevant health and safety regulations. The common practice in maintaining required relatively comfortable indoor conditions is to use mechanical ventilation plus conditioning of air using conventional vapour compression refrigeration. Undesirable aspects of this technology are the use of environmentally harmful refrigerants and use of electricity that in many cases add a substantial running electricity bill. A more sustainable and low carbon alternative to vapour compression refrigeration based air conditioning would be to consider technologies that incorporate natural phenomena of cooling that use low-grade energy from industries or any other renewable source. Here, an evaporation and regeneration-based desiccant cooling system provide a satisfactory alternative for applications where indoor conditions are not very closely controlled. This paper presents a study of a desiccant cooling system. The analysis is based on a software tool; TRNSYS, which enables detailed modelling of the heat and mass transfer process in a desiccant system, particularly the regeneration process and heat/ mass transfer process in desiccant wheel. The performance of a cooling solution is parametrically studied, where the regeneration energy to drive the cooling cycle is determined by examining the humidity ratio and temperature profiles for a year on an hourly basis. The results of the simulations, at different conditions, in an air dehumidifier, are used to propose an optimum coefficient of performance (COP) of the cooling system for a selected case study. Comfort indoor conditions specified in ASHRAE standards, i.e., of 25°C dry bulb temperature and 50% relative humidity were considered in the simulations as the desired indoor conditions. The results indicate that hot water storage at 100°C via a heat exchanger can produce the thermal energy required to heat up the return air at 70°C to regenerate the desiccant. The ventilation air flow rate is maintained at 20,000 kg/hr while the hot water flow rate required to produce the necessary energy of 250 kW is 1.2 kg/so The cooling load met by the system is 120 kW and the calculated coefficient of performance of the desiccant cooling system is 0.48, which saves up to 40% in current electrical energy use of the application concerned. This study makes it clear that use of low grade heat or renewable sources to drive the thermally activated component of a desiccant system have a number of benefits including reduction of peak demand and less energy consumption; i.e., a low carbon footprints. This work shows that a desiccant cooling concept could maintain satisfactory indoor conditions at a lower energy consumption level and presents a sustainable alternative to supplement industrial space cooling demands.
Information on Meteorological Observatories in Sri Lanka
(University of Peradeniya, 2011-11-24) Rekha Nianthi, K. W. G
The systematic official Meteorological station network of Sri Lanka was established in 1865. At present there are 22 main Meteorological Observatories, 38 Agro- Meteorological stations, 35 Automatic Weather Stations (AWS) including some main Meteorological Observatories, and more than 500 rain-gauges maintained by the Colombo main Meteorology Department, various Governmental Organizations (GOs) and Non Governmental Organizations (NGOs) across the country. Many university researchers obtain climatic data from the above stations for conducting climate-related studies on Sri Lanka. The Department of Geography of the University of Peradeniya offers climate related courses for undergraduates as well as postgraduates. It is very important to obtain accurate and up-to-date climatic data (period of the climate data availability, type of climatic parameters and the observation areas) for these purposes. As there is no proper climatic data information available even in the Meteorology Department at Colombo, obtaining up-to-date climatic parameters is very difficult for students as well as staff at the University of Peradeniya when they carry out climatic studies. Therefore, the main objective of this study was to make a small pamphlet of climatic observations based on the data collected from various reports, websites, field observations, and discussions with relevant officers of the observation stations. Based on this information, and up-to date information pamphlet was prepared, fulfilling the main objectives of this project. The prepared pamphlets will be used as teaching material for the relevant courses at the Department of Geography. Copies of the pamphlet will be distributed free of charge to Geography students, some selected Meteorological Observatories visited by the author, Main Library of the University of Peradeniya, library of the Geography Department, and researchers at the University of Peradeniya and other institutions who require this information. This information could be up-dated by the author regularly.

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