http://ir.lib.seu.ac.lk/handle/123456789/3885 2026-04-14T21:24:57Z 2026-04-14T21:24:57Z Madhubhani, K. H. N. Adikaram, A. M. N. M. Amaraweera, T. H. N. G. http://ir.lib.seu.ac.lk/handle/123456789/4146 2021-10-18T19:33:04Z 2019-09-07T00:00:00Z

Title: The possibilities of replenishment and southward extension of Pulmoddai mineral sand belt, Sri Lanka: preliminary phase. Authors: Madhubhani, K. H. N.; Adikaram, A. M. N. M.; Amaraweera, T. H. N. G. Abstract: Techno-economically minable mineral sand deposit of Pulmoddai is extended about 7.2 km along the beach from Arisimale to Kokkilai lagoon mouth of northeastern Sri Lanka. Since the global demand for heavy minerals is increasing, the new expanses for mineral deposits should be investigated. In this background, present study investigated the mineralogical characteristics of sediments that are presently available at extracted areas of Pulmoddai in order to check the replenishment possibility and Thiriyai area, about 5 km southward from the present minable deposits to examine the extension possibilities. At this initial phase of the study, powder X-ray diffractometry (XRD) and grain counting techniques were applied on total sediments collected from both locations and compared the characteristics with general published data of Lanka Mineral Sands Limited, Pulmoddai. The heavy mineral sands recognized by means of XRD results in both places are zircon, monazite, rutile, and ilmenite. The original minable deposit of Pulmoddai indicated 70-80 % of heavy mineral contents whereas that of already extracted area and Thiriyai area shows 48.45% and 24.98 % respectively. Already extracted area of Pulmoddai is mainly composed of monazite, zircon, rutile, ilmenite, and quartz with average percentages of 5.82, 23.79, 5.21, 15.09 and 51.55 respectively. Those average mineral percentages of Thiriyai are 4.62, 13.08, 1.33, 5.95 and 75.02 respectively. The zircon contents of both locations indicate higher values than the average (8-10%) of the minable deposit whereas ilmenite (70-75%) and rutile (8-10%) indicate lower values. The current pattern and the energy of waves would have been the reason for the above changes which need to be measured and confirmed. The results indicate a very little possibility for extractable heavy minerals towards the southward beach of the Pulmoddai deposit. In addition, the refilling nature also negligible for a period of couple of months and it is recommended and needed to monitor the refilling nature for a long-time period. Hence the study suggested getting the maximum usage and profits from the present deposits by developing the quality of the exporting materials.

2019-09-07T00:00:00Z Hisam, M. S. M. Faham, M. A. A. M. http://ir.lib.seu.ac.lk/handle/123456789/4145 2021-10-18T19:33:06Z 2019-09-07T00:00:00Z

Title: Second degree Taylor polynomial approximation of surface integral. Authors: Hisam, M. S. M.; Faham, M. A. A. M. Abstract: Numerical integration is an important mathematical tool used in wide area of Mathematics where scientific computation is required. Finding the exact solution of real world problems involve with definite double integrals is highly challengeable and indeed most of the times not necessary. To resolve these types of difficulties we use numerical approximation techniques. In the literature, there are several numerical integration approaches discussed by many mathematical researchers. In this paper we proposed an approach using Taylor polynomial of degree two. The main objective of this research is to focus on approximating a definite surface integral in order to get a better approximation solution in terms of accuracy. We implemented the proposed approach to some selected functions of algebraic, trigonometry and exponential and compared the obtained results with tangent plane approximation and Simpson’s 1/3rule. It is observed that the proposed method provided more precise results compared to the tangent plane approximation and Simpson’s 1/3rule.

2019-09-07T00:00:00Z Sureskumar, L. Komathiraj, K. http://ir.lib.seu.ac.lk/handle/123456789/4144 2021-10-18T19:33:05Z 2019-09-07T00:00:00Z

Title: Exact solutions of Einstein field equations describing an isotropic fluid sphere. Authors: Sureskumar, L.; Komathiraj, K. Abstract: In recent years a number of authors have found solutions to the Einstein field equations for static spherically symmetric gravitational fields with anisotropic matter. These exact solutions must match at the boundary to the unique Schwarzschild metric which is the exterior space-time for a spherically symmetric distribution of 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. In this work we consider the Einstein field equations in the context of isotropic coordinates for matter distributions with anisotropy pressure in the absence of an electromagnetic field. The main objective of this paper is to generate a class of exact solutions to the Einstein field equations for spherically symmetric relativistic star describing anisotropic fluid sphere. In the methodology we give the expression of the line element modelling the interior of relativistic star which allows us to rewrite the Einstein field equations in terms of new variables. Then the integration of the system is reduced to solving the condition of pressure anisotropy which is the second order ordinary differential equation. We solve the equation by making the choices as rational functions in terms of the radial coordinate for ne of the gravitational potentials and the anisotropic factor which are physically easonable. Exact solutions are found in terms of elementary functions, Bassel functions and modified Bessel functions. A physical analysis indicates that the matter distributions are well behaved and regular throughout the stellar structure. Our results contains uncharged anisotropic models found previously. Some previous well known charged models may be regained as a special case when the anisotropic factor is replaced by a suitable choice of electric field; this suggests that our generalized solution may be used to describe relativistic compact sphere.

2019-09-07T00:00:00Z Kuhanesan, S. http://ir.lib.seu.ac.lk/handle/123456789/4143 2021-10-18T19:33:04Z 2019-10-07T00:00:00Z

Title: Appraisal of the lighting: preliminary study on adequacy level of light intensity in working environments. Authors: Kuhanesan, S. Abstract: Lighting is one of the key physical attributes required for the survival and success of human and other living organisms on earth as it influence the sense of vision. Lighting in built environments or indoor spaces is inevitable in the context of wellbeing and performance of inhabitants. Since people associate activities and illuminance levels in predictable ways, lighting requirement is task and place specific. This study aimed to assess the adequacy of work place lighting in a collection of offices in Vavuniya district based on the day time light intensity measurements using digital Lux meter. easurements were taken at four different categories of work spaces among the sampled locations. In addition to the light intensity measurements, a questionnaire checklist was obtained. This stuy revealed that the mean light intensities of executive rooms, standard office rooms, pooled work spaces and record rooms were 104.52, 74.68, 58.53 and 32.54 lx, respectively: In all the four categories, the light intensities are inadequate with respect to the recommended lighting requirements by 41, 56, 68 and 74 percent, respectively. These findings necessitate the improvement of indoor lighting through a revision of the quality and the positioning of light sources. Such improvements could result sustainable use of energy in this energy crisis era.

2019-10-07T00:00:00Z