NOPR Collection:

PSO driven RBFNN for design of equilateral triangular microstrip patch antenna

2009-08-10T16:30:42Z

Title: PSO driven RBFNN for design of equilateral triangular microstrip patch antenna Authors: Chintakindi, Vidya Sagar; Pattnaik, Shyam Sundar; Bajpai, O P; Devi, S Abstract: Recent advances in computer aided design packages for electromagnetic applications have helped antenna engineers to design, simulate and synthesize antennas efficiently. The PSO driven RBFNN has been developed to calculate the resonant frequency of equilateral triangular microstrip patch antenna (ETMPA). The present paper highlights the simplicity, computational efficiency and accuracy of the proposed method. The achieved results have been compared with published experimental and theoretical findings to validate the presented approach, which seems to be in very good agreements. Page(s): 233-237

Thermal analysis of coaxial coupler for a space helix TWT

2009-08-11T16:30:31Z

Title: Thermal analysis of coaxial coupler for a space helix TWT Authors: Alaria, Mukesh Kumar; Sinha, A K; Srivastava, V Abstract: Thermal and structural analysis of the coaxial coupler for Ku-band 140 W helix space TWT have been carried out using ANSYS software v.10.1 and discussed in the present paper. To evaluate thermal and structural aspects of the coaxial coupler and helix assembly with three APBN support rods, related studies of the coupler assembly with ten turn of helix and output wave guide coupler for the Ku-band 140 W space TWT during extreme case of operation, i.e. at saturation and with perfectly rigid base-plate at 80°C have also been carried out. Page(s): 227-232

Subsurface VLF electric field emissions associated with regional earthquakes

2009-11-03T16:30:21Z

Title: Subsurface VLF electric field emissions associated with regional earthquakes Authors: Singh, Raj Pal; Kumar, Manoj; Singh, O P; Singh, Birbal Abstract: A borehole antenna has been installed at Agra (latitude 27.2^oN, longitude 78^oE), India since 01 June 2006. The subsurface very low frequency (VLF) electric field emissions (f = 3.042 kHz) data has been recorded round the clock for a period of nineteen months from 01 June 2006 to 31 December 2007. This statistical analysis of data is presented in the paper. The occasional amplitude enhancement is observed in the data and examined in the light of magnetic storms, earthquakes, and lightning activities. It is found that in majority of the cases, amplitude anomalies are correlated with moderate seismic activities occurred during the period in the region. The propagation mechanism of VLF signals from the hypocenters of earthquakes to the observing station is discussed in the paper. Page(s): 220-226

Subsurface thermal mapping during contrast seasons over Central Kerala

2009-08-10T16:30:37Z

Title: Subsurface thermal mapping during contrast seasons over Central Kerala Authors: Pious, Michael G; Raja, S Abraham Thambi; Xavier, Oscar Dhas T Abstract: Thermal mapping of seasonal variation of soil temperature at four locations of increasing altitudes in Central Kerala, India during cold and hot weather is presented based on special observations carried out during 1998. Subsurface characteristics like soil temperature, such as time lag, range of temperature; soil heat flux; and speed of the seasonal variation of annual soil temperature are determined and it is seen that lower annual rainfall at Chinnar WLS has influenced temperature range and time lag at different soil depths. The loss or gain of heat either in cold or hot weather periods are totally location based. The velocity of annual wave during cold weather is lower than hot weather as the presence of soil moisture dampens the penetration of the wave into downward layers of the soil except at Silent Valley. Non-linear behaviour of seasonal soil temperature characteristics gives the impression that localized effect due to non-homogeneous soil pattern would have played a part, apart from soil moisture. Page(s): 215-219