Al-Nahrain Journal for Engineering Sciences

1

Harmonic Phase Shifter for Discrete Amplitude Modulation Technique

Anas Lateef Mahmood, Mohammed Tofik Lazim

Pages: 1-12 English

Abstract

In discrete amplitude modulation or
integral-cycle control, subharmonic and higher
order harmonic components are generated in
the three phases of a three phase system.
These harmonic components are found to be
unbalanced in phase displacement. The
correction of the unbalanced phase
displacement angles of a particular
subharmonic or higher order harmonic for this
type of triggering is investigated to solve the
limitation of use of this important type of
control as a drive and many other industrial
applications. The multiple of 2 phase shifting
technique is used to correct unbalanced phase
displacement angles produced in a three-phase
system. A computer-based harmonic phase
corrector is designed and tested with threephase
resistive and induction motor loads. It is
found that there is a well agreement between
the theoretical and experimental results and it
is believed that the major problems associated
with the integral-cycle triggering mode with
three-phase circuits have been solved in the
present work.

Keywords

Harmonics integral cycle control phase angle correction phase shifter power electronics

2

The Linear Vibrational Behavior of Thick Plates Including the Effects of Shear and Rotary Inertia

Muhsin J. Jweeg, Ahmdd A. Hussain, Wisam Abed Al-Sada Kuleiwi

Pages: 13-28 English

Full Text Issues

Abstract

In this work, a suggested analytical
solution for static and dynamic analysis of
(fiber-reinforced) composite laminated
thick plate is developed by using the single
layer theory and first-order shear
deformation theory (FSDT) theory. The
dynamic analysis for equations of motion
for those theories is presented and solved by
using the modal analysis method of forced
vibration. A computer program was built
for this purpose for anti-symmetric crossply
and angle-ply and simply supported
thick laminated plate and the developed
equations are solved by using (MATLAB
V.7) program. The numerical solution by
using finite-element technique is also
adopted using (ANSYS V5.4) package, to
compare the analytical results. Both above
approaches use (FSDT) and include the
effect of shear deformation and rotary
inertia. The results are the deflection, stress
in each layer and (through thickness) interlaminar
shear stress for thick laminated
plates with different boundary conditions
subjected to the static and dynamic loading
conditions. The results presented show the
effect of plate thickness-to-length ratio (h/a),
aspect ratio (a/b), number of layers (N), the
degree of orthotropy ratio (E1/E2), fiber
orientation, boundary conditions,
lamination scheme, and the effect of shear
deformation and rotary inertia on the thick
laminated plate.

Keywords

a suggested analytical solution for static and dynamic analysis of (fiber-reinforced) composite laminated thick plate is developed by using the single layer theory and first-order shear deformation theory (FSDT) theory. The dynamic analysis for equations of motion for those theories is presented and solved by using the modal analysis method of forced vibration. A computer program was built for this purpose for anti-symmetric crossply and angle-ply and simply supported thick laminated plate and the developed equations are solved by using (MATLAB V.7) program. The numerical solution by using finite-element technique is also adopted using (ANSYS V5.4) package and the effect of shear deformation and rotary inertia on the thick laminated plate. aspect ratio (a/b) boundary conditions fiber orientation In this work lamination scheme number of layers (N) stress in each layer and (through thickness) interlaminar shear stress for thick laminated plates with different boundary conditions subjected to the static and dynamic loading conditions. The results presented show the effect of plate thickness-to-length ratio (h/a) the degree of orthotropy ratio (E1/E2) to compare the analytical results. Both above approaches use (FSDT) and include the effect of shear deformation and rotary inertia. The results are the deflection

3

Natural Convection Air cooling of Electronic Components in Partially top vented Enclosures

Ahmed F. Khudheyer

Pages: 29-42 English

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Abstract

The study of natural convection from a
heat source located at the bottom of
partially top vented enclosure is presented.
Air cooling for electronic components
situated at the bottom of a top vented
enclosure is studied theoretically. The flow
was assumed to be laminar, steady and of
constant physical properties. The process
was described by the continuity, momentum
and energy partial differential equations,
which were expressed in Cartesian
coordinates system. Due to the nature of the
studied problem and with proper
transformation, at the dependent and
independent variables, these governing
equations were expressed by a set of
dimensionless partial differential equations.
This set of differential equations is
transformed to set of difference equations
by the implantation of a finite difference
technique. Accordingly, the solutions for
this problem were obtained by the
application of the well-known Gauss Siedel
iteration method. A computer program, by
using FORTRAN-90 language, was
developed to solve the present proposed
mathematical model. According to this
solution; the values of Nusselt number, for
different values of Rayleigh number are
obtained.
Comparisons between the present
obtained results and those results obtained
in previous theoretical results were
performed for parametric variations of the
vent opening size and shape. Also a
correlation for Nusselt number as a function
of Rayleigh number and equivalent
diameter of the vent is proposed.

Keywords

Air cooling of Electronic Components Natural convection vented Enclosures.

4

Evaluation of Reliability of Rupture and Expected Value of Fracture Speed of Ceramic Turbine Wheel Taking the Effect of Residual Stresses

Haider Hadi Jasim

Pages: 43-54 English

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Abstract

In this paper, Weibull uni-axial and multiaxial
distribution function including residual
stresses is developed and applied to evaluate
the reliability of fracture and expected value
of fracture rotating speed of turbine rotor
wheel having blades manufactured from
ceramic material and have inner crack. The
residual stress is measured by X-Ray method.
Third cases are considered, first taking only
the effect of rotational loading (radial and
tangential stresses) in ceramic disc, second
taking the effect of rotational and thermal
stresses in ceramic disc, and third taking the
effect of rotational and thermal stresses in
ceramic blade. As a result, there is a
convergence between results gets from uniaxial
and multi-axial distribution function,
and the residual stresses will reduce the risk
of fracture of wheel and blade. The expected
values of rupture strength of ceramic blade is
higher than of that of disc material, therefore
the failure occurs in blade first than in disc
material in service survival

Keywords

expected rupture strength fracturerotating speed multi-axial distribution function Residual stresses rotational stresses Weibull uni-axial

5

Prediction of Air Flow, Temperature and Humidity Patterns in a Pilot Plant Spray Dryer

Saad Nahi Saleh

Pages: 55-65 English

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Abstract

This paper presents the prediction of air flow,
humidity and temperature patterns in a cocurrent
pilot plant spray dryer fitted with a
pressure nozzle using a three dimensional
model. The modeling was done with a
Computational Fluid Dynamic package (Fluent
6.3), in which the gas phase is modeled as
continuum using the Euler approach and the
droplet/ particle phase is modeled by the
Discrete Phase model (Lagrange
approach).Good agreement was obtained with
published experimental data where the CFD
simulation correctly predicts a fast downward
central flowing core and slow recirculation
zones near the walls.
In this work, the effects of the air flow pattern
on droplets trajectories, residence time
distribution of droplets and deposition of the
droplets on the wall also were investigated
where atomizing of pure water was used.

6

Effect of Salt Content on The Corrosion Rate of Steel Pipe in Turbulently Flowing Solutions

Basim O. Hasan*

Pages: 66-73 English

Full Text Issues

Abstract

The effect of salt content on the corrosion
rate of carbon steel pipe in aerated water
under isothermal turbulent flow conditions
(Reynolds number= 15000-110000 and
temperature of 30-60oC) is investigated by
weight loss method. The test solutions were
distilled water (one time distilled) and sea
water (0.5N NaCl). Also the results of 0.1N
NaCl solution obtained by Hasan [2003]
were considered. The effect of Reynolds
number temperature on the corrosion rate
is also studied and discussed. For each run,
nine specimens of carbon steel were placed
in the test section and the corrosion rate for
each one was determined at every Re and
temperature and the average was taken.
The variation of friction factor with Re and
temperature was determined by measuring
pressure drop across the test section.
The results revealed that the salt content
has considerable effect on the corrosion rate
for the whole investigated range of Re and
temperature. The highest corrosion rate was
encountered in sea water (3.5% NaCl). Also
distilled water causes considerable corrosion
rate but it is lower than for the whole range
of Re and temperature. Also it is found that
Reynolds number increases the corrosion
rate depending on temperature.
Temperature affects the corrosion rate by
changing two main parameters, oxygen
solubility and diffusivity.

Keywords

Carbon steel Corrosion friction factor. salt turbulent

7

Design A Real Time Fast Fuzzy Filter Using Fpga

Khamis A. Zidan, Dhafer R. Zaghar, Ekhlas H. Karam

Pages: 74-83 English

Full Text Issues

Abstract

A nonlinear filtering is an important part
of processing and restoring image sequence.
The computation complexity of these filtering
algorithms makes them difficult for real-time
processing. This paper presents the design
and implementation of a pure fuzzy filter,
which is effective to remove the impulse noise,
and a new method for hardware
implementation into single chip FPGA is
proposed. The construction of the fuzzy filter
is simple and depends on a set of fuzzy rules
to well detect and remove noise pulses.
Simulation results show that the fuzzy filter
exhibits better filtering properties than
standard median filters. The basic FPGA
implementation of the filter cannot reach the
limit for real time processing with good
efficiency. The proposed fuzzy filter is
implemented by modifying the input data
locations and increase the speed of processing
seven times without any increase in the cost.

Keywords

Fuzzy filter impulse noise. Nonlinear filtering Real-Time Xilinx FPGA

8

Analysis and Design of Controller for Level Process Control without Sensor

Zaid Abed Aljasim Muhasain, Saif Abed Aljasim Muhasain

Pages: 84-97 English

Full Text Issues

Abstract

This paper deals with process control,
generalized definition and modeling design of
flow systems and control it based on compare
to constant as principle of operation
approach. After reviewing the operation of
the plant, a compare system between water
level and desire level is formulated to control
flow rate. The scheme is then designed and
tested by Matlab and Simulink Toolbox.
Simulation is presented and shown that on/off
switch with constraint is better and more
versatile compare with conventional
approach.

Keywords

Process; controller; flow.

9

Hybrid Color Image Compression based DPCM and Slant Transform

Ali Hussien mary

Pages: 98-107 English

Full Text Issues

Abstract

Nowadays, still images are used
everywhere in the digital world. Images take
lot of computer space, in many practical
situations, all original images cannot be
stored, and a compression must be used.
Moreover, in many such situations,
compression ratio provided by even the best
lossless compression is not sufficient, so lossy
compression is used.
In this paper ,Differential pulse code
modulation (DPCM) in slantlet transform
and Run Length Code for image compression
is used.
Apply slantlet transform on each
component in the color image(after applying
color space conversion from RGB to
YCbCr)and encoding Y component by DPCM
and encoding Cb and Cr with RLC.The
compression ratio and Peak Signal to Noise
Ratio (PSNR) are used as measurement tools.
When comparing the proposed approach with
other compression methods Good result
obtained.

Keywords

DPCM Image compression RLC Slantlet transform

10

Unsupervised Segmentation Method for Brain MRI Based on Fuzzy Techniques

Nasser N. Khamiss

Pages: 108-115 English

Issues

Abstract

In the present research a novel spatially
weighted Fuzzy C-Means (FCM) clustering
algorithm for image thresholding is presented. The segmentation technique is for magnetic
resonance (MR) images of the brain based on
fuzzy algorithms for learning vector
quantization (FALVQ) by creating of a
combined method in utilizing both LVQ
(learning vector quantization) and the fuzzy
technique. Such a technique is obtaining
more efficient method for the process of
diagnosis of the human brain tumor without
the need for sophisticated steps or human
manner. To speed up the FCM algorithm, the
iteration is carried out with the statistical gray
level histogram of image instead of the
conventional whole data of image. Some
comparisons with classical thresholding
algorithm and fuzzy thresholding algorithm
are also considered in this research. Experimental results on real images are given
to demonstrate the effectiveness of the
proposed algorithm. In addition, due to the
neighborhood model, the proposed method is
more tolerant to noise.

11

Study of Adhesive Wear of Epoxy Reinforced with glass fibers Composite Material

Rula Abdul Khider Abbas, Muzher Ali Sahib, Balkees Mohammed Dyaa

Pages: 116-130 Arabic

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Abstract

The dry wear, compression resistance and hardness of a material that consists of Epoxy reinforced with (25%) ratio of
Glass fiber have been Studied.
A comparison is made between the properties of the composite at temperature ( 20 2 0C) with those of un reinforced
Epoxy to find out the effect of reinforcement on the composite. Volume fraction for specimen was (25%) and the
reinforcement material were continuous fiber oriented in woven raven.
The measurement of wear rate shows a decreases with reinforcement. Compression resistance and Hardness increase
with reinforcement.
The results of compaction have clearly shown that wear rate and wear rate volume increasing normal applied load,
sliding distance, time sliding and hardness of disc. The results also show that wear rate and wear rate volume for all
materials increases with normal applied load and running time. The results also show that wear rate and wear rate
volume decrease with increasing the applied with increasing the hardness of disc and sliding distance.
The topography of some physically tested was studied using optical microscopy

12

Designing an Integrated Systematic Excavator for Agricultural Land

Jassim M. Al-Jaaf, Dr.Kareem K. Mohammad, Najmuldeen Y. Mahmood

Pages: 131-144 Arabic

Full Text Issues

Abstract

In this research a complete design of a plough for agricultural land has been achieved. This is a
theoretical study, design and invention, for it is considered like the ones available now. Precisely, it is a
borne type which can be carried on a vehicle. The optimal design has been reached through making some
primary designs for the research on well excavated land by using spiral digging blades which unearths the
earth on both sides. These blades are fixed on a subjacent system raised by a hydraulic tool when the
digging process finishes. This hydraulic tool enables to obtain a digging successive course by controlling
the process of lowering the lower system gradually to perform the digging process
by a control system connected to the hydraulic tool.
Throughout observation of the previous researches related to plowing [2, 3], it has been found that loads
are put on the most digging blades of the ploughs to increase the digging efficiency and to reach deeper
points. This has been taken into account in our presented research by designing springs between the lower
system mentioned above and the upper fixed system.
From this we get a downward force which will be observed by detailed drawings. Besides, hindering
digging blades by solid materials in the earth has been given attention for they penetrate the earth to a depth
of (30 cm) by our designing the springs to raise the lower system when hindered and later to reach a system
design as a whole

Al-Nahrain Journal for Engineering Sciences

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