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Iraqi Journal of Applied Physics

المجلة العراقية للفيزياء التطبيقية

ISSN: 18132065 23091673
Publisher: iraqi society for alternative and renewable energy sources and techniques
Faculty:
Language: English

This journal is Open Access

About

The Iraqi Journal of Applied Physics (IJAP) is a peer reviewed journal of high quality devoted to the publication of original research papers from applied physics and their broad range of applications. IJAP publishes quality original research papers, comprehensive review articles, survey articles, book reviews, dissertation abstracts in physics and its applications in the broadest sense. It is intended that the journal may act as an interdisciplinary forum for Physics and its applications. Innovative applications and material that brings together diverse areas of Physics are particularly welcome. Review articles in selected areas are published from time to time. It aims to disseminate knowledge; provide a learned reference in the field; and establish channels of communication between academic and research experts, policy makers and executives in industry, commerce and investment institutions. IJAP is a quarterly specialized periodical dedicated to publishing original papers, letters and reviews in: Applied & Nonlinear Optics, Applied Mechanics & Thermodynamics, Digital & Optical Communications, Electronic Materials & Devices, Laser Physics & Applications, Plasma Physics & Applications, Quantum Physics & Spectroscopy, Semiconductors & Optoelectronics, Solid State Physics & Applications, Alternative and Renewable Energy, Computers Networks and Applications.

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Contact info

P. O. Box 55259,
Baghdad 12001,
Iraq
Website: www.iraqiphysicsjournal.com
Email: admin@iraqiphysicsjournal.com
Email: editor_ijap@yahoo.co.uk

Table of content: 2009 volume:5 issue:2

Article
Phase Noise Compensation for Coherent Orthogonal Frequency Division Multiplexing in Optical Fiber Communications Systems

Authors: J.K. Hmood
Pages: 3-10
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Abstract

In this paper, the Coherent Optical (CO) systems using Orthogonal Frequency Division Multiplexing (OFDM) for dispersion compensation is demonstrated. The Quadrature Amplitude Modulation QAM-OFDM transmitter signal was controlled by the Mach-Zender Modulator (MZM) which modulates the laser source with wavelength of 1550nm. The heterodyne receiver with dual-polarization optoelectronic down-converter is used to obtain good coherent detection without using optical phase locked loop. The analytical part was done using a software simulator. All the proposed system components were simulated using VPIphotonic simulation software for testing CO-OFDM system. The transmitted signal, optical spectrum, eye diagram and constellation diagram was obtained to evaluate system performance.


Article
Signal Mechanism Analysis of Fiber Arrival Time in Fiber Optic Pin

Authors: M.S. Mehdi --- M.T. Al-Obaidi
Pages: 13-17
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Abstract

In this research there has been a description and studying for Fiber Arrival Time (FAT) technique. The research has depended on a theoretical analysis way for the FAT technique that is mainly used as a sensor and detector for the detonation waves (thermal waves) that is produced by high explosives. Several explanations for the output optical signal in FAT diagnostic have been introduced, the suggested by previous researches as well as the suggested by this research. Wien's displacement law has been depended to measure the wavelength of the output optical signal. Also, heat measurements have been performed in this research and each of heat transfer coefficient and heat gradient in FAT diagnostic has been measured. There has been a comparison by using several other elements like copper, silver and gold as probable substitutes for aluminum that has been used in FAT.


Article
Power Reduction in Flexible Silicon Thin Film Digital Circuits

Authors: T.J. Alward --- K.R. Wissmiller --- J.E. Knudsen
Pages: 19-23
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Abstract

Amorphous silicon (a-Si) thin-film circuits promise robust, lightweight, flexible displays and digital computation. Here, several methods for reducing standby-power while retaining logic state are investigated for such circuits. Lacking a PMOS load transistor, the conventional approach for retaining state is to dynamically shift values through memory elements. We investigate other methods and demonstrate 36x power savings by introducing a non-shifting, refresh based operating mode.


Article
Range-Coverage Extension Using Smart Antennas in Mobile Communications Systems

Authors: A.H. Sallomi --- S.R. Salim
Pages: 25-28
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Abstract

The growing demand for wireless communications services is constantly increasing the need for better coverage and quality service. Smart antennas employ collection of individual elements in the form of an array, so, they give rise to narrow beam with increased gain when compared to conventional antennas using the same power. The array gain is the average increase in signal power at the receiver due to a combination of the signals received at all antenna elements. The gain provided by adaptive antenna array is proved to provide an extension in a communication range that depends on the number of array elements. The simulation had done by using power exponent radio wave propagation model shows that the gain provided by smart antennas can extend the range of a cell to cover a larger area and more users than would be possible with omnidirectional or sector antennas. The increase in gain leads to employ fewer base stations to cover a given area.


Article
Analysis and Design of Combined Fractal Dipole Wire Antenna

Authors: F.J. Jibrael --- H.A. Hammas
Pages: 29-32
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Abstract

This paper presents the analysis and design of a small size, low profile and multiband combined fractal Koch dipole antenna. The proposed antenna design, analysis and characterization have been performed using the method of moments (MoM) technique. The new designed antenna has operating frequencies of 440MHz, 1194MHz, and 5272MHz with acceptable bandwidth, which has useful applications in communication systems. The radiation characteristics, VSWR, reflection coefficient, and input impedance of the proposed antenna are described and simulated using 4NEC2 software package. Also, the gain of this proposed antenna is calculated and described in the three planes: XZ-plane, YZ-plane, and XY-plane, where the antenna is placed in the YZ-plane.


Article
Efficiency Enhancement of Photovoltaic Silicon Cell by Ultrashort Laser Pulses

Authors: A. Taleb --- K.A. Al-Naimee --- S.S. Ahmed --- R. Meucci
Pages: 33-35
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Abstract

We present an experimental evidence of the effect of the femtosecond laser pulses on the spectral response of the Silicon photovoltaic cell. The response of this device is covering the visible to near infrared spectral region. The responsivity of the photovoltaic solar cell is enhanced from 0.18A/W to 0.25A/W and/or the conversion efficiency increase from about 9% to about 14% due to irradiation effect. All treatments and measurements are made at room temperature. Results show that the responsivity is enhanced and the nano-structured groves of the 700-900 nm range are observed.


Article
Optimization of Composition, Structure and Characteristics of Metal in Arc Deposition

Authors: V. Jakovlev --- S. Shanchurov
Pages: 37-40
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Abstract

In this work, the chemical composition of carbide was changed at shock loading. The formation of austenite from ferrite or pearlite and the change of carbide composition runs as a result of diffusion processes, therefore it was supposed, that as a result of micro- and macro-plastic metal deformation, which is conducted by heat evolution, the iron diffusivity in local amounts of the alloy should increase considerably and therefore it should be dissolved in carbides. The increase of iron contents took place in carbides of M7C3 and M23C6 as a result of tempering or contact-shock circular loadings at the expenses of diffusion processes. It was explained that strengthening phase of developed alloy 2M3 was carbides MC, M7C3 and M23C6.

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