Open Access Short Research Article

Investigation of the Absorption Lines of a Kr - Ne - Mixture as Wavelength Standards for Optical Communication Systems in the Range of 1270 nm - 1640 nm

M. Schröder, U. H. P. Fischer

Physical Science International Journal, Page 1218-1224
DOI: 10.9734/PSIJ/2014/10978

Optical communication systems are since the last 25 years the backbone of all international data and telecom communications. Up to now, more than 10 TBit/s can be distributed via one optical fiber in long-haul systems. This was realized by the use of highly parallel multi-channel transmission via many colors, called Wavelength division multiplex (WDM). Here, the International Telecommunication Union specified the channel location into a frequency space grid with 100GHz distance in the infrared regime from 1300nm to 1640nm. To avoid interference between these densely arranged transmission channels, each transmitter output frequency has to be stabilized exactly in its center frequency to others. To supervise and stabilize the transmission comb, absolute frequency standards are very helpful to be integrated into optical cross-connect stations. Using excited state absorption lines of a Nobel gas is an easy way to generate reference frequencies, because these states are very stable and very small in linewidth. A well known method is the detection of the absorption by the opto-galvanic effect (OGE). Here, a tube is filled with an gas like Kr and the detection of the absorption will be performed by an electrical signal of the absorption cell via electrodes with high voltage supply. Many atomic transitions are near by to the ITU grid frequencies of ITU G 652 Recommendation.

In this article we show for our knowledge at the first time all absorption lines of krypton and neon mixed gas in the whole ITU transmission range between 1270nm -1640nm using optogalvanic spectroscopy. The temperature dependence of the possible wavelength drift of the detected lines was also measured using a climate chamber between 10ºC and 50ºC. The measured absorption lines are within the tolerances of the detection equipment in comparison to literature. The measured stronger lines are separated between 5 nm and 30 nm in the detected wavelength range. Hence the creation of a frequency grid using 27 pure stable absorption lines of Kr as a wavelength standard for optical communications systems using these lines would be possible. Combining the Galvatron detection of Kr lines with active feedback to a multi-channel laser source, a high stable reference source for optical WDM networks would be available in future.

 

Open Access Short Research Article

Image Content Enhancement of Natural Images Using Genetic Algorithm

Chaahat ., Santoresh Kumari, Parveen Lehana

Physical Science International Journal, Page 1244-1259
DOI: 10.9734/PSIJ/2014/6891

Image contents play a vital role in various images. In this paper, genetic algorithm has been investigated for the content enhancement of the natural images. The algorithm was effective as the contents of the images became clear with the successive iterations. The algorithm was applied on the image for 1000 random DNAs with successive iterations. The analysis of the results showed that the contents of processed images were enhanced with the successive iterations with respect to the unprocessed input images. For comparison, the preliminary investigations were also carried out by comparing the results of enhancement of the images using GA and other techniques such as used in Photoshop. The analysis showed that for obtaining a comparable quality using other techniques such as Photoshop, a lot of manual adjustments of brightness, colour, and contrast are needed to get an enhanced image.

 

Open Access Original Research Article

Irradiation Enhancement of Electrical Properties of Passive Impurities in Silicon Crystals

H. N. Yeritsyan, A. A. Sahakyan, V. V. Harutyunyan, N. E. Grigoryan, V. A. Sahakyan

Physical Science International Journal, Page 1225-1234
DOI: 10.9734/PSIJ/2014/11458

Radiation defect formation processes in silicon crystals for the cases when concentrations of electrical non-active impurities (oxygen, carbon) prevail over main impurities determining silicon conductivity, are being covered in this paper. The role of interstitial atoms and vacancies, oxygen and impurity atoms in formation of radiation defects of A- and E-centers and divacancies, as well as their influence on electrical and optical properties of silicon crystals are shown. Energy levels of radiation defects in forbidden gap of silicon and their introduction rates were defined based on temperature dependencies of the concentrations of charge carriers at different irradiation doses. The capture probability of interstitial atoms and vacancies by main and passive impurities is taking into account. In addition to known A- and E-centers, along with disordered regions (clusters), a new radiation centers with energetic levels at Еc - 0,33eV; Еc -0,40eV and Еc -0,22eV were detected and studied. The first level is connected with silicon interstitial atoms, whereas the second corresponds to divacancies and the last one is identified as divacancy + oxygen.

Open Access Original Research Article

Corrosion Inhibition of Aluminium Alloy in 0.75 M KOH Alkaline Solution Using Xylopia aethiopica Seed Extract

O. F. Nwosu, E. Osarolube

Physical Science International Journal, Page 1235-1243
DOI: 10.9734/PSIJ/2014/9928

The present study investigated the corrosion inhibition of Al alloy in 0.75 M KOH solution at room temperature using X. aethiopica seed extract. Gravimetric technique was employed in the study. It was revealed that the presence of the spice extract in the test solution retards the corrosion rate. The calculated inhibition efficiency from the inhibitor surface coverage was observed to increase linearly with the inhibitor concentration. The consideration of the Langmuir adsorption isotherm indicated that the mechanism of adsorption is Physisorption. Temkin isotherm models explained that there were lateral attractions of the inhibitor molecules on the Al alloy surface. Flory-Huggins isotherm model confirms that there is bulky displacement of water molecules on the metal surface due to the presence of the inhibitor molecules.

 

Open Access Original Research Article

Heat Transfer Aspects on Rotating MHD Two-phase Convective Flow through an Inclined Channel in the Presence of Electric Field

P. Sri Ramachandra Murty, G. Balaji Prakash

Physical Science International Journal, Page 1260-1279
DOI: 10.9734/PSIJ/2014/11471

Steady, laminar, incompressible and fully developed fluid flow of two immiscible electrically conducting fluids between two infinite inclined parallel plates has been studied when the two plates are maintained at different constant temperatures T_w1 and T_w2. A constant magnetic field B0 is applied transverse to the plates and a constant electric field E0 is applied across the channel. The whole system is rotated at an angular velocity about an axis perpendicular to the channel plates. The transport properties of the two fluids are taken to be constant. Approximate solutions for temperature, primary and secondary velocity distributions are obtained using regular perturbation method because the resulting equations are coupled and non-linear. It is observed that in the short circuit case (E = 0), as rotation increases both the primary velocity and temperature distribution decrease where as secondary velocity oscillates. It is also observed that for the open circuit case (E=±1) as the rotation increases the secondary velocity becomes oscillatory. In case of E=-1, the increasing rotation tends to accelerate the primary velocity, but in case of positive E, it accelerates the primary velocity in the opposite direction. For the open circuit case (E = ±1), as the rotation increases the temperature decreases for small values of rotation and increases for large rotation.

Open Access Original Research Article

Non-wave Solutions of the Maxwell-Einstein Equations

Yuriy N. Zayko

Physical Science International Journal, Page 1280-1292
DOI: 10.9734/PSIJ/2014/12654

This article is devoted to treating of non-wave, i.e. instanton solution for the Maxwell-Einstein equations. Equations for the field of instanton and metric are derived. Metric of pseudo-Euclid space which is corresponding to transition between degenerate classical vacua of problem and is connected with presence at the space infinity divergent and convergent spherical electromagnetic waves is studied. An expression of the instanton is received and it’s size is found. Value of pseudo-Euclid action is calculated. It is shown that instanton violates so called “week energetic condition” which is essential for space-time singularities proving.

 

Open Access Original Research Article

Effects of Suction and Thermal Radiation on Heat Transfer in a Third Grade Fluid over a Vertical Plate

I. G. Baoku

Physical Science International Journal, Page 1293-1310
DOI: 10.9734/PSIJ/2014/8964

Aims: An analysis is presented to investigate the effects of suction and thermal radiation on the unsteady convective flow and heat transfer in a third grade fluid over an infinite vertical plate. The plate is porous to allow for possible wall suction.

Methodology: The governing time-based coupled partial differential equations, subjected to their boundary conditions, are solved numerically by applying an efficient and unconditionally stable Crank-Nicolson finite difference scheme. Numerical calculations are carried out for different values of dimensionless parameters in the problem.                                        Results: An analysis of the results obtained establishes that the flow field is appreciably influenced by suction and viscoelastic parameters.

Conclusion: An increase in the suction parameter is observed to decrease the fluid velocity. The result also shows that the temperature distribution decreases with an increase in the thermal radiation parameter.

 

Open Access Original Research Article

The Energy-driven Model and the Scaling Relations in Galaxies

Man Ho Chan

Physical Science International Journal, Page 1311-1317
DOI: 10.9734/PSIJ/2014/12867

It is known that the radiation emitted by the accretion disk of supermassive black hole can heat up the surrounding gas in the protogalaxy. If the gas particles are in hydrostatic equilibrium during the galaxy formation and the cooling of the protogalaxy is mainly driven by the gas expansion, the correlation between the supermassive black hole mass MBH and velocity dispersion can naturally arise. Also, ve more related scaling relations can be obtained, which all agrees with empirical ts from observational data. Therefore, this modied energy-driven model may provide a clear picture on how the properties of a galactic supermassive black holes are connected with the kinetic properties of a galaxy.