AL-Rafidain Engineering Journal (AREJ)

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.

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).

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.

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.

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.

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.

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.

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 .

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 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.

T he aim of this study is to investigate the effect of the magnetized fuel on the performance
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 .

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 soilpore
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.
A n 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 up
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.

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.

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 bitserial
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).

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.