Vol.2, No. 2(2006)

 

Al-Khwarizmi Engineering Journal,

 

Vol.2, No. 2(2006)

 

   

No. Author Name  Title Abstract Full Text
1 Ahmed S. Hadi  Performance of Turbo-Codes with Some Proposed Interleaver Schemes This paper describes a number of new interleaving strategies based on the golden section. The new interleavers are called golden relative prime interleavers, golden interleavers, and dithered golden interleavers. The latter two approaches involve sorting a real-valued vector derived from the golden section. Random and so-called “spread” interleavers are also considered. Turbo-code performance results are presented and compared for the various interleaving strategies. Of the interleavers considered, the dithered golden interleaver typically provides the best performance, especially for low code rates and large block sizes. The golden relative prime interleaver is shown to work surprisingly well for high puncture rates. These interleavers have excellent spreading properties in general and are thus useful for many applications other than Turbo-codes. Full Text
2 Ali  M. N. Hassan Design & Implementation of High Switching & Low Phase Noise Frequency Synthesizer  This research  describes the design & implementation of frequency synthesizer using single loop Phase lock loop with the following specifications: Frequency range (1.5 – 2.75) GHz,Step size (1 MHz), Switching time 36.4 µs, & phase noise @10 kHz = -92dBc & spurious -100 dBc    The development in I.C. technology provide the simplicity in the design of frequency synthesizer because it implements the phase frequency detector(PFD) , prescalar &  reference divider in single chip. Therefore our system consists of  a single chip contains (low phase noise PFD, charge pump, prescalar  & reference divider), voltage controlled oscillator , loop filter & reference oscillator. The single chip is used to provide the following properties : •    Low power consumption. •    Small size, light weight. •    Flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning. •    High reliability. Full Text
4

Dr. Jawad Kadhim Uleiwi

Buckling Analysis of Unidirectional Polymer  Matrix Composite Plates

 

    This study deals with the estimation of critical load of unidirectional polymer matrix composite plates by using experimental and finite element techniques at different fiber angles and fiber volume fraction of the composite plate.     Buckling analysis illustrated that the critical load decreases in nonlinear relationship with the increase of the fiber angle and that it increases with the increase of the fiber volume fraction.     The results show that the maximum value of the critical load is (629.54 N/m) at ( = 0) and (Vf = 40 %) for the finite element method, while the minimum value of the critical load is (49 N/m) at  ( = 90) and (Vf = 10 %) for the experimental results.  The results also indicated that the maximum difference between the finite element analysis and experimental work is about (11 % ) at (  = 0) and (Vf = 40 %). Full Text
5

falah f. hatam 

Dr.Maaed Rezouki Hassan

A theoretical study for increasing production of electric power from Iraqi steam power plants.

This article conclude a theoretical study for the possibility to produce additional electric power from Iraqi steam power plants by  cutting – off high-pressure feed water heaters .  Three separated steam power plants which Dura , south –Baghdad and Nasria were studied . The investigation showed the possibity of increasing the electric power from 10 to 15% for Dura and Nasria , whereas 6% for south – Baghdad . According to the nowadays of operation to Iraqi steam power plants , the results showed that by cutting–off high  pressure feed water heaters we can generate additional electric power about 250 MW during 3-4 hrs. daily. In addition, the fuel consumption can be reduced in comparison with diesel generator, which is used to produce the same add- ional electric power.  Full Text
6

Dr.Adnan Nama Abood

Dr.Nabil Kadim Abdul-Sahib

Welding of Low Alloy Steel DIN 15Mo3  by MIG/MAG Spot

 This research deals with the effects of welding variables using MIG/MAG spot by using Argon (Ar) gas and CO2 to show their effect on the mechanical characteristics and microstructure of low alloy steel type DIN15Mo3 and determine the optimum condition for the process of welding ; current & time. The results show the possibility of using CO2 and also Ar in low alloy steel welding with a little decrease in the shear force of not more than 13% for 4mm thickness and time 2sec. The shear force increased when using Ar instead of CO2 to be , The shear force reach 36KN when using Ar at 2mm thickness  time of 8 sec and current of 220 Amp. , when used CO2 instead of Ar decreased shear force to 31KN reach decrease rate 13%  while for a thikness of 4mm , time 8sec and acurrent of 290Amp. it was 37.9kN , when used CO2 became 30.9KN decrease rate 18.5% and for a thikness of 6mm , time 8 sec and 450Amp. current it was 39 KN when used CO2 it become 37KN redusing rate 5.20% .The diameter and penetration of welding have straight relation with the increase of current and time. 

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