IMPACT : International Journal of Research in Engineering & Technology

11-20

Authors: S. Sikkandar, S. Jayakumar, S. Bangaru Sudarsan Alwar, S. Srinivasan & S. Gunasekaran

The present investigation aims to determine the mineralogical composition of certain human gallstones using Powder X-Ray Diffraction technique (PXRD). The minerals present in the samples are identified by analysing Bragg’s angle (2θ), Lattice spacing (d), Miller Indices (h k l) and full width at half maximum (FWHM) values of the sample with the standard data. Results suggest that calcium phosphate or calcium carbonate with or without magnesium content is the most predominant mineralogical component in gallstones

27-32

Authors: Innocent A. J, Jacob O. E, Chibuzo G. C, James I & Odeh D. O

Information on the availability of global solar radiation of a given geographical location is an essential factor in developing suitable solar energy system and devices for various applications. In this work, data for daily sunshine duration were used to estimate mean global solar radiation in Gusau city, Nigeria. The daily sunshine hours were measured for period of 6 years (1995 - 2000) from which the monthly mean values were determined. Angstrom-Prescott model was then used to estimate the global solar radiation based on the monthly mean sunshine hours. The values of global solar radiation for Gusau ranged from 16.1676 - 21.6536 MJm-2day-1 under the period of study with mean value of 18.8015 MJm-2day-1. These values can be utilized in the design and performance of solar energy systems for the location

47-64

Authors: R K SETHI & ADITYA GOEL

Next generation communication network will be required to provide increased data rate efficiently along with the flexibility to adapt to various dynamic traffic patterns in a cost effective manner. The optical fiber communication system can do the same along with low losses and good quality of transmission. In the recent past, the enormous growth of network traffic on deployed optical communication networks forced the demand for a more constructive utilization of the channel capacity of the optical fiber communication channel. In near future, the next generation optical links are going to carry 10 / 40 Gbps per wavelength. The two windows at 1310 & 1550 nm provide low attenuation with transmission bandwidth of approximately 50 Tbps. Optical fiber communication system are primarily operated at wavelength near 1550 nm in order to match with the minimum loss point of silica fiber and hence maximize transmission distance. Unluckily, at this wavelength, there is a considerable quantity (typically 17ps/nm/km) of dispersion that restricts the achievable transmission distance. As the data transmission rate keeps increasing, the dispersion causing pulse broadening results in Inter-Symbol Interference (ISI), this becomes an important limiting factor for signal degradation of fiber optical network. The dispersion restricts the highest transmission data rate and longest transmission distances for the repeater less optical communication link [1]. Many efforts have been drawn to the development of dispersion compensating devices / techniques to recover or prevent the broadening of signal pulse. The basic solution for this is to use an efficient equalizer. Orthogonal Frequency Division Multiplexing (OFDM) is a very auspicious data transmission process for the high data rate transmission due to its capacity to handle ISI, resilience to the dispersive channel, high bandwidth utilization efficiency and superior performance. It overcomes the problem of inter-symbol interference due to dispersion, by simultaneously modulating and transmitting a number of orthogonal sub-carriers at a low symbol rate, which makes the symbols period much longer than the channel impulse response. The OFDM is a multiple sub-carrier modulation technique which is highly spectral efficient and have a dynamic tolerance to dispersion, thereby making it an excellent dispersion compensation scheme for using the exiting optical communication networks for next generation dynamic traffic pattern. Therefore, the combination of optical communication system and OFDM is the highly efficient technique for the next generation long haul high capacity communication network. This work investigates the use of OFDM as a technique to fulfil these needs for next generation optical communication system. These involve design, modelling, simulation and comparative performance analysis of the optical communication system with and without using OFDM for dispersion compensation. A novel scheme of tuneable dispersion compensation using OFDM is presented in this work. The system performance has been analysed in terms of BER, constellation diagrams and OSNR for optical communication system with and without using OFDM. OFDM is shown to outperform in high data rate optical communications system for the long haul high data rate transmission with high bandwidth utilization efficiency.

77-80

Authors: RAJKUMAR JHAPTE & KALPA KRISHNAN

Arc furnace represents one of the most intensive and disturbing loads in the electric power system concerned about. Electric arc furnace can go from zero to full load many times an hour as arc struck and broke in the furnace. Voltage flicker, a phenomenon of annoying light intensity fluctuation is a major concern for both power companies and customers. These fluctuation contribute to the voltage variation in the electrical distribution system causing flicker. Therefore, an accurate model of an arc furnace is needed to test and verify proposed solutions to this end. This paper, presents the results of a study, where furnace arc is modelled using both chaotic and deterministic elements. Voltage fluctuations (Sag), is captured using the well-studied circuit whereas a dynamic model in the form of differential equation is used for the electric arc. Simulation model is analyzed using Fuzzy Logic