http://ir.lib.seu.ac.lk/handle/123456789/2269 2026-04-14T21:24:57Z 2026-04-14T21:24:57Z Balasooriya, N.W.B. http://ir.lib.seu.ac.lk/handle/123456789/2347 2021-10-18T19:16:23Z 2013-12-03T00:00:00Z

Title: Preparation of exfoliated Mica using phlogophite Authors: Balasooriya, N.W.B. Abstract: Mica is a generic term for long group of poly-silicates mineral with a unique structure. Mica can be found in nature in the form of sheets connected together by surface force between by layers. Mica has often been used for a wide variety of economical uses including the electronic industry, paints and fillers. The expansion behavior of the natural mica has been studied for industrial use of exfoliated mica. The development of exfoliated mica technology was initiated with a two prolonged approach namely to develop cheaper value added products. Natural mica (Phlogophite) acquired from Feldspar mine at Rattota, Matale, Sri Lanka. The selected mica samples were washed and crushed by using an agate mortar and separated for few minutes to the particle size of 63um and approximately separated in to l-2mm particle size by using a mechanical sieve-shaker. Lithium Nitrate was used for chemical intercalation with mica. The expansion factor (degree of expansion) was determined using the ratio between original volume and maximum volume which was measured. Characterization of the exfoliated mica was carried out with X-ray powder diffractometry (Cu K a, Philips X-Ray generator) and The SEM studies are performed on a JSM 6400 scanning electron microscope. Thickness of the intercalate layers, interplanar distances were studied using 001 diffraction pattern. The exfoliation behavior of the natural graphite mainly depends on the particle size & shape and experimental conditions such as temperature and further it depends on the order of the crystal lattice, the secondary structure; size and shape of the particles, the amount of gangue minerals with the mica and the technological pretreatment of the mica.

2013-12-03T00:00:00Z Akmal Jahan, MA.C. Razmy, A.M. Ragel, R.G. Deegalla, S. http://ir.lib.seu.ac.lk/handle/123456789/2346 2021-10-18T19:16:23Z 2013-12-03T00:00:00Z

Title: Performance analysis of supervised learning classifiers for the prediction of child birth weight Authors: Akmal Jahan, MA.C.; Razmy, A.M.; Ragel, R.G.; Deegalla, S. Abstract: Even though the technology advancement has helped improving medical and health sectors, high infant mortality rate is still considered as a serious problem in developing countries. Low birth weight (LBW) plays a major role in infant mortality. There are several reasons for LBW of a child. There is a wide variation of LBW within Sri Lanka in different geographical areas. Particularly the districts belong to plantation workers, Monaragala, Ampara and Poionnaruwa districts show the highest percentages of newborns belonging to the LBW category. From the statistics Ampara district shows 17% of LBW. The objective of this work is to find a suitable way to predict the child weight using the existing pattern of low birth weight in Ampara region. There is a need to find an algorithm with good performance among several existing supervised learning classifiers to construct a decision model. This work was carried out among 2700 pregnant mothers throughout the MOH offices in Ampara district. Initially the existing data were manually classified into three classes such as Normal Birth Weight (NB), Low Birth Weight (LB) and High Birth Weight (HB). Several important parameters were captured from the data set. C4.5, CART and ID3 supervised learning classifiers in Weka data mining and machine learning tool were used in this experiment. The data were handled through three major processes namely as pre-processing, attribute selection and construction of decision trees using classifiers. The missing values in the huge data set were handled in pre-processing. The useful and most significant parameters were selected and ranked using feature selection process. Three decision tree algorithms were used to construct decision tree. The accuracy and time complexity for the tree construction were measured using the experimental tool Weka by applying 10-fold cross validation from the experimental results on accuracy and time complexity of the decision tree classifiers, C4.5 produces higher accuracy as 86.15% and the time complexity is less than 1 minute. Considering the time complexity and accuracy C4.5 works effectively compared to the others. Therefore C4.5 was selected as a best classifier to construct decision tree model for the prediction of child weight in Ampara district.

2013-12-03T00:00:00Z Komathiraj, K. http://ir.lib.seu.ac.lk/handle/123456789/2345 2021-10-18T19:16:23Z 2013-12-03T00:00:00Z

Title: Some new static anisotropic spheres Authors: Komathiraj, K. Abstract: In recent years, a number of authors have found solutions to the Einstein field equations for static gravitational fields with anisotropic matter. The models generated are used to describe relativistic spheres with strong gravitational fields. It is for this reason that many investigators use a variety of techniques to attain exact solutions. The exact solutions may be used to study the physical features of charged spheroidal stars. I found a new class of exact solutions to the Einstein field equation for an anisotropic sphere with the particular choice of the anisotropic factor A= pc — pr, the difference between the radial and the tangential pressures of the fluid sphere and one of the gravitational potential Z. The condition of pressure anisotropy was reduced to a recurrence equation with variable, rational coefficients which can be solved in general. Consequently the exact solutions to the Einstein field equations corresponding to a static spherically symmetric gravitational potential was found in terms of series. I generated two linearly independent solutions by placing restriction on parameters arising in the general series. Some brief comments relating to the physical features of the model are also made.

2013-12-03T00:00:00Z Jafeen, M. J. M. Careem, M. A. http://ir.lib.seu.ac.lk/handle/123456789/2344 2021-10-18T19:16:21Z 2013-12-03T00:00:00Z

Title: A study on electrochemical stability of polypyrrole films in concentrated LiCl aqueous electrolytes Authors: Jafeen, M. J. M.; Careem, M. A. Abstract: Polypyrrole (PPy) conducting polymer films operating in aqueous electrolytes have a shorter cycle life and such a system has, therefore, limited use as far as applications are concerned. This can be rectified to some extent when ionic liquids are used as cycling media. However, the cost involved is prohibitive. The aim of this study is to investigate the possibility of using concentrated alkali halide electrolytes to improve the cycle life of PPy films Polypyrrole films doped with large surfactant anions, dodecyl benzene sulfonate, (PPy/DBS), were formed on quartz crystals using the galvanostatic electropolymerization technique. The redox behavior of the films up to 300 cycles in LiCl aqueous electrolytes of selected concentrations ranging from 0.1 - 8 M, was investigated using cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) techniques. During the first cycle, while large water movement was observed along with the counter ions in dilute electrolytes, such water transport in concentrated electrolytes was found to be very low. On continuous cycling the shape and capacity of the cyclic voltamograms changed significantly in dilute electrolytes. But in highly concentrated electrolytes the cyclic voltammograms remained unchanged with the number of cycles indicating that the PPy/DBS films had stable cycle life in such electrolytes.

2013-12-03T00:00:00Z