Published Articles Archive

Abstract
Polypyrrole-poly(vinyl alcohol) (PPy-PVA) conducting polymer composite films were prepared on Indium Tin Oxide (ITO) glass electrode from an aqueous solution containing pyrrole monomer, p-toluenesulfonate electrolyte and poly(vinyl alcohol) insulating polymer by electrochemical method. The prepared composite films were characterized by conductivity and electromagnetic interference (EMI) shielding measurements, dynamic mechanical analysis (DMA) and optical microscopy. The conductivity data of PPy-PVA shows that with the increase in PVA concentration in aqueous pyrrole solution used to prepare the films, the conductivity of the prepared PPy-PVA composite films increased upto a certain level and later it showed a decreasing trend with further increase in PVA concentration used to prepare the composite films. The dynamic mechanical analysis (DMA) shows the evidence of the enhanced mechanical properties of PPy-PVA composite film over PPy film. The optical micrographs show the changes of morphology of the prepared composite films with the PVA concentration. The results of electromagnetic interference (EMI) shielding effectiveness measured in the microwave range of 8-12 GHz show that a shielding effectiveness of 45.67 dB was exhibited by PPy-PVA composite films.

Abstract
This paper deals with the communication system that uses M-ary Phase-Shift-Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) to transmit information using OFDM technique over Rayleigh communication channel. In terms of Symbol Error Rate (SER), the performance of different modulation schemes using OFDM techniques in Rayleigh channel is analyzed. For different types of modulation schemes (QPSK, 16-QAM, 16-PSK, 64-QAM, 64-PSK) gray coded bit mapping has been used with OFDM techniques. So, better performance is shown in different modulation scheme by using gray coded bit mapping. Here in this paper, it is our goal to show the way through which the SNR result varies between M-PSK and M-QAM.

Abstract
In this work, an iodide copper vapor laser (CuI) has been designed and fabricated. The effect of different operational parameters such as frequency and buffer gas pressure on output power laser have been investigated to determine the optimal condition of frequency and neon gas pressure. Based on experimental results, the maximum output power of about 0.5W is obtained at 16 kHz of frequency and 30 torr of Ne gas pressure. Moreover the experimental results of CuI laser have been compared to the similar data for the other halide copper lasers such as CuBr and CuCl. The output power of CuI laser is less than that of others. The optimum frequency of lasers have different values, but the optimum gas pressures are the nearly same for three lasers, at the same conditions.

Abstract
The determinations of the age of the oldest objects in the universe, giving a lower limit of the age of the universe itself, are of great
interest in astrophysics and cosmology. With the detection of the long-lived isotopes of thorium and uranium in a single star, their
application as cosmochronometers has become possible. With network calculations, the production of Th and U can be studied for
different input of the underlying mass model and the astrophysical environment. A comparison with the abundance pattern of very
metal-poor stars can serve as a reference to check the validity of the assumptions and to better understand their influences on the
final outcomes of the calculations. Once the initial amount of thorium and uranium are known, age estimations of stellar objects can
be accomplished. Network calculations were performed that allow flexibly changing and studying the astrophysical environment in
a parametric way, as well as the underlying nuclear physics input in terms of the final abundance pattern. The network used here
includes more than 7000 nuclei, reaching far outside in the neutron rich area. The most relevant fission processes were implicitly
taken into account. For all three massmodels a good agreement between the final abundance pattern and the abundance distribution
for six metal poor stars is demonstrated. Network calculations are thus an appropriate tool to study and analyze the production of
the cosmochronometers Th and U, which can be used for age-determinations for stars. A more detailed study of their production
paths is necessary to reduce uncertainties with respect to the underlying massmodel and astrophysical environment.

Abstract
The South Peninsular India is known to have very high levels of natural background radiation due to the monazite rich beach sand. Primordial uranium is ubiquitous and the heaviest radio toxic trace element available in all terrestrial substances at varying levels depending on the geology of the region. Uranium series supports several short-lived radioisotopes during its decay including radium. Uranium in drinking water is important in terms of the ingestion dose also. This report depicts the results of uranium analysis of 600 water samples collected from the south coast peninsular region extending parts of Kerala and Tamilnadu states of India through fission track registration technique. Results of the analyses of water samples collected from different sources in the south coast of India show that uranium concentrations vary from 0.82 μg/l to 7.32 μg/l equivalents to the specific activity of 10.33 Bq/m3 and 92.23Bq/m3, respectively. Estimated daily intake of uranium through drinking water ranges from 20.22 to 18.58mBq/kg and is lower than the recommended limits of intake. The heterogeneity in distribution of uranium in water bodies is due to the presence of monazite sand deposited in the coast over the years.

Abstract
The simplest solution to Einstein's field equations is the Schwarzschild solution. This solution is not able to describe any non-spherical shaped objects. Some stars and galaxies are ellipsoidal. Consequently, the gravitational field around these objects should be different in comparison with the spherical form. This paper is considering a new line element so that we are able to construct not only spherical objects but also we are able to explain an ellipsoidal object too. This new line element is more accurate and complete than the Schwarzschild line element. In this research, we see that the Schwarzschild line element and its solution is only a part of the whole work, which we have done. For more consideration, we applied this metric to an arbitrary object in the next step. Moreover, we used this line element for the solution of a planetary orbit of an ellipsoid planet by using Einstein’s field equations. These equations used for the exterior solution of an ellipsoidal celestial object.