Engineering and Technology Journal

This paper is concerned with the design and simulation of fixed frequency microwave
oscillator. Scattering parameters of the active device (MESFET-Afm02n8b) are used to
design and synthesize the oscillator. The computer aided design package (Microwave
Office 2000 version 3.22) is employed to optimize oscillator subcircuits performance
such as resonator, feedback, and output matching network. Two techniques are
employed for the analysis purposes. The first method involves the open-loop gain and
phase response versus frequency, the second method considers the oscillator as one-port
with negative resistance. Fixed frequency oscillator at 7GHz is realized and tested.

This paper deals with the evaluation of the elastic deflections and bending moments
for orthotropically reinforced concrete rectangular slabs supported on three variously
restrained edges with the fourth edge free and subjected to uniformly distributed load.
Six cases are considered for such slabs to cover all possible restraining conditions at the
three supported edges. Based on the finite difference approach, equations are derived to
calculate the maximum values of the positive and negative bending moments as well as
the maximum deflection in any of these six slab cases caused by the applied uniform
load.

This paper presents a high resolution Digital Pulse Width Modulation "DPWM" for the
voltage regulator application. The PWM signal is generated by using two fast clock
counters. In this approach, the pulse width is combined from two parts depending on two
counter schemes. MSBs of the DPWM generates first part of pulse that achieved by a first
counter-phase comparator scheme, and the LSBs of the DPWM generates second part of
pulse that obtained through a second counter- phase comparator scheme. The resolution of
present pulse width depends on the resolution of second counter.
The developed pulse width modulator has high precision, good linearity, and wide duty
cycle range. Further, it can be flexibly reconfigured for multi-phase PWM operation with no
restriction on duty cycle range. In this work, a 714 kHz switching frequency DPWM module
with 9- bit resolution is tested by simulation program

A numerical investigation of laminar mixed convection around horizontal isothermal
cylinder is presented. The free stream direction varies between the vertically upward
(assisting flow) and vertically downward (opposing flow). The governing equation in terms
of the stream function, vorticity and temperature are expressed in a body-fitted coordinate
system and solved numerically by explicit method. Results are presented for Reynolds
number from 20 to 300 with Grashof numbers from 0 to 120000. The Prandtl number was
kept constant at 0.7. Correlation for the average Nusselt number around the cylinder in the
forced and mixed convection regime is suggested. Comparison with previous theoretical and
experimental results shows good agreement. It was established that the maximum heat
transfer from cylinder occurs in case of assisting flow

In this paper, a comprehensive investigation of a microstrip antenna
performance covered with a dielectric layer has been presented. An aperture
coupled antenna has been designed as a case study. Antenna parameters have
been evaluated with and without the presence of a dielectric layer with different
thickness values. Theoretical performance evaluation of this antenna for different
cases, corresponding to the different dielectric thicknesses, has been assessed
using the method of moment (MoM) based EM simulator IE3D, v.10.06. A large
number of dielectric thickness variations have been modeled, in an attempt to
provide accurate antenna parameters response through this range. Simulation
results show that the antenna resonant frequency is reduced as the dielectric layer
thickness is increased. To maintain the resonant frequency, the antenna
dimensions must be scaled down as a result of the existence of this layer. In
addition, results also show that, as the dielectric layer thickness is increased, the
resulting antenna gain decreases.

In this paper, we analyzed the sequencing situations on two machines where the machine
setup time is not independent of processing order.
A real case study of Hadhramout Industrial Company Complex, Mukalla, Yemen is taken
as a model. Data is collected and analyzed using MS-Excel by different methods. The problem
formulation has been presented. Multiple solutions were obtained by applying sequencing
methods. The comparison of different solutions is done to choose the optimal solution. The
time is reduced by 23% to perform the group of jobs and the setup time is reduced 30.5% as
well as the mean flow time is reduced by 30.5%.

In this research hydrogenation kinetic of alpha-methylstyrene (AMS) on Pd/Al2O3
catalyst was studied. The reaction is mildly exothermic (ÄH=-109 kJ/mol). Intrinsic
kinetic law was investigated under wide range of operating conditions 0.1 and 0.2 gm
catalyst loading, 0.5-100 wt% AMS, 10, 15 and 20 bar pressure and 343-373 K
temperature.
The experiment data are fitted to estimate the kinetic parameters for different reaction
mechanisms by using ACM (Aspen Custom Modeler) software. Finally the results of
produced reaction mechanisms are compared with experimental results to obtain the
optimum reaction mechanism

Barium and Holmium have been introduced into polycrystalline lead iodide during
solution growth of thin films. Electrical characterization (current vs. voltage measurements ,
resistivity, carrier concentration and mobilities as a function of the doping concentrations)
clearly demonstrates that both dopants introduce donor level in the PbI2 band gap and
compensate for the native acceptor defects of lead iodide, Barium as a dopant having the
greater influence.

In this paper the Internet was used as a media for transmission an ECG (Electro-
Cardio-gram) signal from a patient directly to a remotely reside doctor or consultant who
will respond via the same media directly. The ECG signal (at patient side) has been
compressed in a manner to achieve low bandwidth requirement by using Matlab
capabilities. Also, at consultant side the original signal is reconstructed using the same
capabilities of Matlab. The Internet works as the center of communication between the
two sides. A database was used to store the patient information which can be handled
easily by consultant. Respecting the internet no more than a simple rented web site was
required as a file storage shared between the consultant and patient. The results show
that the received signal at the doctor side after reconstruction had the complete and
compatible to the signal used for diagnosis.

An exclusive study has been done on experimental investigation of the two-phase flow
pressure drop in an air-non-Newtonian liquid (CMC solutions) system in bubble column.
The effects of gas and liquid flow rate on two-phase pressure drop have been illustrated.
Experiments in a 0.2-m diameter, 2.4-m-high bubble column were carried out to determine
the pressure drop. At the selected superficial velocities, two flow regimes were observed:
heterogeneous bubbling flow and heterogeneous churn turbulent flow, they were identified
through the slope changes in the plots of pressure drop and gas holdup. The pressure drop
did not seem to be affected by the superficial liquid velocity and it was increased as the
superficial gas velocity decreased or the CMC concentrations increased.

Many high performance aircraft suffer from a dynamic instability problem at relatively
high Mach number and altitude regimes known as Dutch roll instability. In this study the
aircraft Dutch-roll and lateral –directional state variables may be enhanced using the yaw
damper and washout filter. The Aircraft Dutch-roll damping is improved by identifying a
suitable feedback gain matrix plus preserving the airframe's low-frequency behavior by the
use of a washout filter with a time constant. An intermediate change in terminology is used to
illustrate the procedure for including a washout filter into the aircraft lateral state equation
formulation. A stability augmentation system (SAS) and a numerical model constructed for a
Mig-21 aircraft are solved to illustrate the proposed procedure. The numerical results show
that it was sufficient to use (SAS) including both yaw damper and washout filter to improve
the aircraft sideslip angle, roll rate and roll angle response in a short time. Finally, the
verification of the aerodynamic characteristics of present model was made by comparing the
results of the method used (Low order three dimensional Panel method) with that of Cy-20
aircraft flight data test.

A low profile compact microstrip antenna for GPS (L1/L2) application has been
presented in this paper. The proposed antenna design is based on the 3rd iteration
Minkowski-like pre-fractal geometry. The resulting antenna design offers a compact size,
low profile and light weight making it suitable for use in handheld applications. Antenna
performance has been evaluated using the EMSightTM from the Applied Wave Research.
The proposed antenna has shown to possess two resonance bands (for return loss .-10
dB) covering the two GPS bands. Reasonable radiation characteristics have been achieved
at the GPS frequencies (L1:1575.42 } 10.23 MHz, L2:1227.60 } 10.23 MHz) with good
circular polarization characteristics. Realized circular polarization Bandwidths (for axial
ratio . 3 dB) are found to cover adequately those required for these GPS bands.

In this paper, a problem for Offline Signature Recognition and Verification is presented. A
system is designed based on two neural networks classifier and three powerful features (global,
texture and grid features). Our designed system consist of three stages: the first is preprocessing
stage, second is feature extraction stage and the last is neural network (classifiers)
stage which consists of two classifiers, the first classifier consists of three Back Propagation
Neural Network and the second classifier consists of two Radial Basis Function Neural
Network. The final output is taken from the second classifier which decides to whom the
signature belongs and if it is genuine or forged. The system is found to be effective with a
recognition rate of (%95.955) if two back propagation of the first classifier recognize the
signature and (%99.31) if all three back propagation recognize the signature.

A three-dimensional study of developing fluid flow and heat transfer through
wavy and diverged-converged ducts were studied numerically for a Prandlt number 0.7
and 5.85 and compared with flow through corresponding straight duct. The Navier-
Stokes and energy equations are solved by using control finite volume method.
Development of the Nusselt number in wavy and diverged-converged ducts are
presented for different flow rates (50

Keywords

forced convection
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numerical study
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wavy duct
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diverged-converged duct

In this paper, the finite element method is utilized as a tool for carrying out different
analyses of stone column–soil systems under different conditions. A trial is made to
improve the behaviour of stone column by encasing the stone column by geogrid as
reinforcement material .
The program CRISP2D is used in the analysis of problems. The program adopts the
finite element method and allows prediction to be made of soil deformations considering
Mohr–Coulomb failure criterion for elastic-plastic soil behaviour.
A parametric study is carried out to investigate the behaviour of ordinary and
encased floating stone columns in different conditions. Different parameters were studied to
show their effect on the bearing improvement and settlement reduction of the stone column.
These include the length to diameter ratio (L/d), shear strength of the surrounding soil and,
the area replacement ratio (as) and others.
It was found that the important increase in strength of stone column occurs when it
is encased by geogrid for (length/diameter) L/d = 8 while in case of L/d = 4, a slight
increase in the bearing improvement ratio at the early stages of applying the load is
obtained and then the value of (q/Cu) for both ordinary and encased stone columns is the
same.

This research deals with the study the effect of adding the silica particles and
alumina particles separately with different ratio (5, 10, 15, 20, and 25 pphr) on the
hardness and wear rate of natural rubber NR and styrene butadiene rubber SBR. The
results show that the hardness increases with the increase the loading level of reinforcing
particles, while the wear rate decreases with the increase the loading level of the
reinforcing particles. The largest value of the hardness and the lowest value of the wear
rate were for styrene butadiene reinforced with 25 pphr of silica as compared with
natural rubber. Also the reinforcing by SiO2 increases the hardness and decreases the
wear rate more than of Al2O3.
The results indicated that the hardness and the wear rate for SBR and NR
reinforced by SiO2 and Al2O3 at (25 pphr) illustrated in the following table:

The goal of this paper is to estimate the states of two-phase permanent magnet synchronous
motor (PMSM). The system is highly nonlinear and one therefore cannot directly use any linear
system tools for estimation. However, if one can linearize the system around a nominal
(possibly time-varying) operating point then linear system tools could be used for control and
estimation. Firstly, the error covariance matrices of measurement and process would be derived
when the system inputs and outputs are subjected to uncertain variations. Then, the corruptednoise
nonlinear model of the system will be discretized and extended to be suitable for applying
standard discrete Kalman filter (KF) for state estimation purpose. The entire state estimated
system has been modeled using MATLAB/SIMULINK blocks. The state estimation algorithm
and the motor discretized model are coded inside special S-functions of m-file type.

The Architecture is a cultural monumental . It has its action's and reactions
and its position and historical distance . The house , as it concern , one of the
Architectural Phenomenon , has effected from the past till now with the conceptual
and theoretical changes . and since the last has effected in the house as a whole ,
from side . And the product of its elevation , from the other side . And as a result of
no assistance of any research which study the development of Baghdad's house's
elevations during the twentieth century . And to have a completed knowledgement
about this subject , therefore the research problem has been :
"There is no completed knowledgement about the development that
happened in the Baghdad's house's elevations at the twentieth century according to
the cultural and effectiveness"
The work study different points : the architectural development , the development
in the house's elevations at the twentieth century , the theoritcal frame , The
work, Practical study , Results , conclusions and advices
The results refer to the development that happened in the Baghdad's
elevation's houses during the twentieth century.The cultural and social theory
effected in the elevations,coused a harmonycal changes between the elevations and
the theory.
The results refer also to the local and historical values beside the new and
developmental theories and a large interested in the formal values.

Recent advance in high-speed cutting materials have focused on reinforcing
alumina with different carbides and nitrides in order to improve hardness and fracture
toughness, this composites materials use in cutting tools application. The present study
concert on properties of cutting tools made by Al2O3 reinforcement by Mg-PsZ. The
added weight fractions from ZrO2 are (15% , 20%). The materials cold-pressed at (5, 7,
10) ton, at (1400, 1500, 1600 Co) in two hours. The result shows increasing in hardness
and densities values of specimen with the increasing the mixing percent also, there is a
signification enhancement of specimen properties with increased temperature and
pressure, the approperte temperature is 1600 Co with pressure 10 ton.

This work is concerned with a study of dry sliding wear of α–Brass (70/30) with
addition of lead and tin(3%wt) for each one alloy. Three brass alloys were prepared by
melting and pouring in steel molds. A Pin -on-Disc technique was used. The effect of
applied loads and sliding times on wear rate were examined. The results show that the
wear rate increases with increasing applied loads and with increasing sliding time at
constant sliding speed (2.7m/s) while hardness of steel disc was 35 HRc .
The results also show that the brass alloy containing 3% tin has more
wear resistance than that of other brass alloys.