Print ISSN: 1813-0526

Online ISSN: 2220-1270

Volume 19, Issue 6

Volume 19, Issue 6, Summer and Autumn 2011, Page 1-150

Performance Evaluation of Soft Handover in WCDMA System

S.H. Fasola; S.A. Mawjoud

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 1-14
DOI: 10.33899/rengj.2011.26582

In this paper soft handover parameters in WCDMA system are investigated. They include the effect of imperfect power control on the downlink capacity and power assignment to the mobile station, the micro diversity gain which represents the gain in the downlink direction, and the macro diversity gain which represents the gain in the uplink direction.
The results showed that the power control error increases the total power consumption by the mobile station which leads to decrease the capacity (number of users per cell). Soft handover decreases the fade margin which leads to improve the coverage area. During soft handover the mobile station needs lower signal to noise ratio compared with no soft handover to obtain the specific bit error rate.
Keyword: Cellular Mobile System, Soft Handover (SHO), Power Control.

AC Current Harmonics Reduction& improve the power factor for Single Phase controlled Rectifiers Using Current Injection Method

Aasef. A.Saleh; Basil M.Saied; Hussein I.Zynal

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 1-15
DOI: 10.33899/rengj.2011.26565

The AC electrical distribution system works at limited values of voltage and frequency levels. The increase of using non linear loads and loads those connected by electronic keys produces non sinusoidal voltages and currents in the distribution systems.
Single and three phase, controlled and uncontrolled rectifiers, are used for obtaining DC current and voltage. This affect the shape of the supply current which included many harmonics. The quality and quantity of the power obtained are affected as a result. The shape of the current wave is therefore attracted the attention of many researcher groups. The line injection by current harmonics is one of the most important and effective techniques used for such treatment.
The aim of this research work is to reduce the harmonics in the input current and improving the power factor of the single phase, controlled and uncontrolled, rectifiers. This is usually carried out by employing injection method technique with reversible polarity through connecting a passive resonance circuit between the input and output of the rectifier. The passive resonance circuit creates second harmonic current which will circulate between the AC and DC sides of the rectifier and decreases the total harmonic distortion (THD). In this work, the ratio of (THD) is reduced from 50% to 10% with power factor increased nearly to unity for different values of the trigger angle (α).

Theoretical and Experimental Results of Substrate Effects on Microstrip Power Divider Designs

Dr. Asaad M. Jassim Al-Hindawi; Suhair M. Al- Ali

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 15-25
DOI: 10.33899/rengj.2011.26603

The effects of substrate materials on the design of microstrip power divider are investigated theoretically and experimentally. Three different dielectric substrate materials are chosen ; Duriod 3003, G10/FR4 epoxy Glass and Duriod 3010 to be studied. A three-way double-stage power divider is designed at S-band frequency of 2.25 GHz and etched on each studied substrate separately. The substrate effects of large difference in dielectric constant and the dissipation factor ; on the characteristics and performance of the microsrip circuits are taken into consideration in the present study. The circuit designs presented here, are analyzed using the Genesys CAD program and implemented and tested experimentally. The simulated and measured results are compared , discussed and indicate that significant changes in the characteristics of the microstrip power divider are observed.

A Study For Refrigerant's Characteristics to Choose the Optimum For Ejector Refrigeration System

Mohammad S. Al - Dabbagh; Dr. Adnan M. Al Saffawi

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 16-29
DOI: 10.33899/rengj.2011.26568

Refrigeration systems needs efficient refrigerant to perform it's determined objective, so, an optimum refrigerant, must have a good and desirable characteristics as compared with other refrigerants as well as a high coefficient of performance for the working cycle, which results for minimizing operating power to attain determined refrigeration capacity.
A variety kinds of improved refrigerants had been appeared within the last twenty years, and many countries did large efforts to phaseout some refrigerants, or at least reduce it's usage, that's for it's ozone layer depletion and it's bad influence on environment and climate.
This research deals with a comparative study between many Refrigerants on the basis of it's characteristics , COP and compressibility factor in ejector refrigeration system to select the optimum to be used in this system.
From this study results , the optimum refrigerant is Butane (R – 600), which have a good characteristics , a relatively high compressibility factor values , and a COP value of (0.615) , which is a good result as compared with other refrigerants included the phaseouted for it's bad influence on environment and climate.

Microcontroller Based Maximum Power Point Tracking For Photovoltaic Solar Panel

Museeb M. Jasim; Kamil G. Salih; Rasha E. Majed

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 26-39
DOI: 10.33899/rengj.2011.26604

Many papers are published in the past and at present time which operate the solar photovoltaic (PV) panel at its maximum power point, by implementing an analogue or digital electronic circuits which are known as maximum power point trackers (MPPT). The main purpose of the researches are to obtain maximum power from the (PV) solar panel under different atmospheric conditions. In this paper a digital technique based on microcontroller type 8051 is used to design and implement the (MPPT) using maximum power point voltage method. The proposed (MPPT) consists of three major units (i) the solar (PV) panel (ii) the DC/DC step down inverter (iii) the control unit and computation of maximum power point based on microcontroller

Effect of Ultrasonic Waves on Sedimentation Characteristics and sludge Dewaterability

Ahmed Yassin Shehab

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 30-39
DOI: 10.33899/rengj.2011.26569

This paper studied the effect of ultrasonic waves on sedimentation characteristic of activated sludge and there causes on filamentous growth, as well as its effects on the sludge ability dewaterability. The power of ultrasonic waves was set at (0.35W/cm2) while the frequency and contacts time was varied to (31،44،55 KHz) (10،20،30،40 min) respectively. An instrument with (0.5 L) in volume was used to applied ultrasonic waves, it was connected by plastic tube with a completely mixed activated sludge reactor. Testes shows that the relationship between contacts time of ultrasonic and sludge volume index (SVI) was a sagged curve with an optimum point, that’s means there was a specific contacts time to achieved an optimum sedimentation characteristics at specific frequency. As well as Testes shows that the relationship between contacts time and specific resistance (r) was a linear in first order, that’s indicates the ability of dewaterability of sludge decreased with the increasing of ultrasonic contacts time. Also results shows that the effect of ultrasonic waves on activated sludge related conversely with its frequency.

Optimal Power Flow Solution with Maximum Voltage Stability

Dr. Ahmed Nasser B. Alsammak

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 40-53
DOI: 10.33899/rengj.2011.26606

This paper presents an Optimal Power Flow (OPF) formulation that is based on multi-objective optimization methodology, which can minimize both of operating costs and losses and it would at same time result in maximizing the distance to voltage collapse. A “Maximum Distance to Voltage Collapse” algorithm, which incorporates constraints on the current operating condition, is firstly presented, while OPF formulations which incorporate voltage stability criteria is secondly presented. The algorithm built on Matlab-Simulink is tested on an IEEE 6-bus test system using a standard power flow model, where the effect of maximum loading point limits is demonstrated.

Fatigue Behavior of Al – 4wt%Cu / SiCP and Al - 4wt%Cu/ Al2O3P Composites

Salim Aziz Kako

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 54-61
DOI: 10.33899/rengj.2011.26607


Aluminum – copper ( Al – 4wt%Cu ) alloy metal matrix composites MMCs reinforced with 0.5 ,1.0 ,1.5 % wt of both SiC and Al2O3 particles were fabricated by stir-casting .The effects of SiC and Al2O3 particles content on the fatigue behavior of the Al – 4wt%Cu unreinforced base alloy and the resulted composites were investigated. The results show that fatigue strengths of base alloy increased with increasing weight fractions of ceramic particles and the fatigue strength of MMCs reinforced with SiC particles is higher than that of reinforced with Al2O3 particles

Experimental Study into Effect of Developing Section Length on The Heat Transfer Process in a Horizontal Annulus

Dr. Akeel A. Mohammed; Ameer A. Jadoaa

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 62-72
DOI: 10.33899/rengj.2011.26608


An experimental investigation has been presented to study the heat transfer process in thermally developed region of horizontal concentric annulus with an adiabatic inner tube and uniformly heated outer tube. Three lengths of entrance section have been used to achieve the hydrodynamically fully developed flow before test section with (L/Dh=50,75 and 100). The study has covered the range of Reynolds number (450≤ Re≤2000) and Richarson number (0.1≤ Ri≤ 0.7). Results show that the heat transfer process in the lower part of annulus is better than that in the upper part; and the vortex strength increases as Rayligh and Rynolds numbers increase. An empirical correlation for the average Nusselt number as a function of Rayliegh and Reynolds numbers and L/Dh has been deduced and compared with available literatures to give the same trend and behavior.

The Effect of Impinging Jet on the Flow and Heat Transfer from Isothermal Moving Plate

Dr. Ahmed Waheed Mustafa

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 73-83
DOI: 10.33899/rengj.2011.26609

The effect of impinging uniform jet on flow and heat transfer over isothermal moving plate is investigated. The flow and temperature fields are studied numerically with different jet velocity ratio (jet to plate velocity ratio 0-5). The laminar flow field is analyzed numerically by solving the steady, two-dimensional incompressible Navier-Stokes and energy equations. A collocated (non-staggered) grid is used in the momentum equations, which discretized by finite volume method, SIMPLE algorithm is used to adjust the velocity field to satisfy the conservation of mass. The range of Reynolds number is (Re = 10 - 100). The results show that at high jet velocity ratio (V/U = 5) and Reynolds number (Re = 100), the rate of heat transfer from the plate is doubled.

Effect of Magnetizing the Fuel on the Performance of an S.I. Engine

Dr. A. R. A. Habbo; Raad A. Khalil; Hassan S. Hammoodi

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 84-90
DOI: 10.33899/rengj.2011.26611

The aim of this study is to investigate the effect of the magnetized fuel on the perfor-mance of spark ignition engine. The engine performance was observed by examining the engine brake power (BP) , thermal efficiency , specific fuel consumption (SFC) and exhaust emissions .The fuel is subjected to a magnetic field which is placed to fuel supply line to magnetize the fuel before admitted to the engine cylinder. Two types of magnetic coils were adopted in this study, the first one with 1000 Gauss and the second with 2000 Gauss. Experimental tests were conducted at a speed of 2000 rpm , compression ratio 8 , wide open throttle (WOT) and ignition timing was set between 50 and 300 BTDC . The results show a significant improvements in engine performance, the thermal efficiency and engine power increased by (4 %) and (3.3 %) respectively when a magnetic coil of 1000 Gauss is used, and a reduction in the specific fuel consumption by (12.8 %) was achieved. However, when the magnetic coil of 2000 Gauss is used the brake power is increased nearly by (16.4 %) , thermal efficiency showed an improvement nearly by (7.6 %) , while the specific fuel consumption is decreased by (21.3 %) with respect with no magnetic field case . The exhaust gas emissions show a reduction nearly by (80 %) of CO and by (44 %) of HC when the magnetic coil of 1000 Gauss is used. A further reduction nearly by (90 %) of CO and by (58 %) of HC is obtained when the magnetic coil of 2000 Gauss is used .

Nonlinear Coupled Finite Element Analysis of A Dam-Reserviour Under Dynamic Loading

Dr. O. F. S. Al-Damluji; Dr.A. Y. Th. Al-Saaty; Dr.R. M. Al-Nuaimi

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 91-111
DOI: 10.33899/rengj.2011.26613

This research presents a nonlinear coupled analysis of a dam-reserviour problem with aspects of class I coupling for fluid-structure interaction and class II coupling for soil-pore fluid–structure interaction under earthquake excitations using finite element method. The analysis involves the compressibility of water, the flexibility of the dam, the earthquake excitation, the structural damping and the material nonlinearity on the response.
An efficient computer program is developed for this analysis from the original computer code named as MIXDYN. The new software for analyzing the coupled behaviour is established using the pressure formulation for modelling of fluid and the u-p formulation for modelling of soil-pore fluid.
Two differenent schemes for coupled field problems are implemented in the new computer code using the staggered partitioned solution technique in terms of sequential execution of single-field analyzers .Eight-nodded two-dimensional isoparametric element is adopted for idealization each of soil, fluid and structure. The Drucker Prager model is used to simulate the behavior of soil and concrete. Implicit-Implicit Newmark’s scheme with corrector predictor algorithm is employed for time integration of the equations of motion. The capability and the efficiency of the model are found to be very useful.

ANN Model for Predicting Ultimate Shear Strength of Reinforced Concrete Corbels

Abdalkader A. Mohammed; Dr. Salim T. Yousif

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 112-123
DOI: 10.33899/rengj.2011.26615


The artificial neural network (ANN) model was developed using previous experimental data on Reinforced concrete (RC) corbels to simulate the behavior of RC corbels. The neural network model has six input parameters representing the concrete compressive strength ( ), shear span (a), effective depth (d), corbel width (b), area of main reinforcement (As), area of secondary reinforcement (Ah), one output parameter representing the ultimate shear load (Vu). A back propagation neural network (BPNN) with the log-sigmoid activation function is adopted due to its accuracy of prediction. The ANN model is constructed using the experimental data from the literature. The ANN predicted ultimate shear load which compared with those calculated by ACI318-08 code Formula and Russo model. The neural network model is to predict the shear load of RC corbel more accurate than the ACI318-08 code Formula, and Russo model. Through the parametric studies using the ANN model, the effects of various parameters such as ( , a, d, b, As, and Ah) on the behavior of RC corbel were shown. The results reveal that the proposed network model captures the RC corbel underlying shear behavior very well.

Design and FPGA Implementations of Four Orthogonal DWT Filter Banks Using Lattice Structures

Zainab R. S. Al-Omary; Dr. Jassim M. Abdul-Jabbar

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 124-137
DOI: 10.33899/rengj.2011.26616

In this paper, lattice structures for DWT are introduced through the design and FPGA implementations of the orthogonal Daubechies filter banks of orders 2, 4, 6 and 8. Multipliers and shift-add methods are both used to perform multiplication operations for these types of filter banks. Two implementation techniques are introduced, namely; the pipelining technique that is efficient from the throughput point of view, and the area efficient bit-serial implementation technique. The obtained results show the ability to achieve high throughput using pipelining (with 2 output samples / clock) on behalf of the area allocation. While bit-serial technique minimizes the allocated area on behalf of the throughput which may decrease with increasing filter order. As compared with other recent implementations, the results of implementing the designed filter banks using the SPARTAN-3E FPGA kit are efficient in minimizing implementation complexity to 0.584 - 0.712 of its corresponding values for different structures in recent hardware implementations. It is also obtained that the resulting structures can operate at high frequencies (up to 47.09 MHz).

Best Wavelet Filter for a Wavelet Neural Fricatives Recognition System

Dr. Ahmed Maamoon Alkababji

Al-Rafidain Engineering Journal (AREJ), 2011, Volume 19, Issue 6, Pages 138-150
DOI: 10.33899/rengj.2011.26617

Direct recognition of phonemes in speaker independent speech recognition systems still cannot guarantee good enough recognition results. But grouping phonemes at first then trying to recognize the phoneme itself is a promising field. On the other hand wavelets are widely used in speech and speaker recognition systems, this is motivated by the ability of wavelet coefficients to capture important time and frequency features. In this work the effect of the wavelet filter type on the efficiency of a phoneme recognition system is investigated (specifically fricatives). The Probabilistic neural network was used as a pattern matching stage for its well known and power full ability in solving classification problems. It was found that the Daubechies wavelet family (generally from db15 to db23) is a good candidate for a fricatives phoneme recognition system that is based on wavelets as a feature extraction stage.