Dijlah Journal

This work is aimed to study effect of alumina coating on the partially stabilized zirconia alumina
composite (YPSZ/ Al2
O3
) on the microstructure, phase transformation and hot corrosion performance of eutectic molten salt V2
O5
+ 45 wt% Na2
SO4
and comparing with conventional YSZ.Both
the pure alumina and YPSZ are sprayed by using atmospheric plasma spray APS. Hot corrosion
for composite is done by exposing the samples to an isothermal air furnace testing at900 °C for
different exposure times of40 and 80 hours. Upper surface plan views of the coatings are examined using SEM. The hot corrosion test products are determined using EDS, EPMA and XRD. The
results indicate the higher hot corrosion resistance of YSZ/ Al2
O3
composite coatings compared
with conventional YSZ sprayed coatings. Degradation of YSZ due to the presence of eutectic
harsh salt attack is occurred by destabilization of yttria from the zirconia yttria coatings. This will
lead to disrupt transformation from metastable tetragonal phase (t’) to monoclinic phase (m). the
corrosion products of YVO4
produce by leaching process. During exposure the composite to the
molten salt the Al2
O3
is reacted with vanadate to form a low-melting liquid eutectic phase, leading to dissolution of Al2
O3
in molten NaVO3
Na2
O–V2
O5
–Al2
O3
. The pores and cracks within the
YSZ coating are filled with Al2
O3
. The absences of leaching of yttria in under layer for composite
coatings is related to the absence of pockets of open porosity and cracks due to elimination after
alumina layer applied.

This study involves the welding technology of carbon steel pipes which is widely used in many
engineering applications, in particular refrigeration systems and boilers. The chemical
composition of this metal shows that are close to steel grade A192 according to ASTM standards.
This metal shows an excellent weldability and enhanced potential for the use of high strength TIG
weld consumable. TIG weld filler type ER70S-6 is used to join two pieces of steel pipes using
TIG welding machine. This experimental work also involves the evaluation of the integrity and
mechanical prosperities of the weld joint. That was done by conducting a several destructive and
non-destructive tests on the weld joints such as, Tensile, bending, hardness, x-ray and Liquid
penetrant). The tests program confirmed that, the weld joint maintains a good mechanical
properties and acceptable weld defect

Two feed forward multilayer neural network (FFMNN) architecture have been constructed. The
first model has two hidden layers, 20 neurons for first layers and 30 neurons for second layers.
The first model utilized to control the mechanical properties (yield strength, tensile strength and
hardness) which are the inputs to this model. The model gives the carbon percentage and the heat
treatment type and temperature as response to the required mechanical properties. The second
model is implemented to predict the effect of carbon, quenching and tempering temperature on
mechanical properties of both tensile strength and hardness of low and medium carbon steel. It
has two hidden layers, 30 neurons for first layers and 60 neurons for second layers. In addition,
the effect of different carbon percentages and heat treatment temperature for quenching were studied on the mechanical properties of low to medium carbon steel. The results of Vickers hardness
showed that hardness, yield strength and tensile strength were increased with increasing the carbon percentage, quenching temperature and decreasing the tempering temperature. The neural
networks models showed good agreements with experimental data. The correlation coefficients
for the first model versus the experimental data are 0.9917, 0.9782 and 0.9954 for yield strength,
tensile strength and Vickers hardness respectively. Higher correlation coefficients were obtained
for the second modelling

This study was conducted to determine the prevalence of obesity among young people and to determine whether there was any association between overweight and obesity with the ABO blood
group. The total number of students tested was 200 students (100 from each gender), in aged
between 20 and 23 years. They took the weights and length of the individuals and entered the
body mass index (BMI) equation according to the index of body mass by dividing the weight in
kilograms per square meter in length and comparing the values calculated by the standard values
shown in Table (3) and calculating the percentages for each weight category. Blood groups were
recorded from the information taken for the some research members, and the test was performed
in a way that matched those who did not know their blood samples and other random samples to
verify the credibility of the information. The results were identical to the information obtained
directly. The results were as follows: 2%,the proportion of individuals with a weight below normal
distributed equally between males and females and 71% is the proportion of individuals with normal weight, boys scored the highest percentage of girls while the proportion of people who suffer
from obesity is 25% and the increase in girls by 2% of male. At the level of the blood groups, O
group was the most overweight, followed by A, B, and AB, and only 4% in the O group.

The present study included preparation and characterization of step-wise functionally graded
materials (FGMs) for hip joint replacements, prepare by using powder technology technique. ceramic – metal FGMs specimens (AZT Group) that made from nano Al2
O3
, nano 3YPS-ZrO2
and
Ti – alloy (Ti-6Al-4V), consist of 10 layers begins with 100% Ti – alloy that gradually decreases
and Al2
O3
and 3YPS-ZrO2
increases, finally ends by 100 %Al2
O3
. Physical tests for AZT – Group
were done in order to characterize FGMs prepared, which includes apparent density & porosity
for green compact and for sintered compacts also relative apparent density percentage, all physical
tests showed increase in apparent and relative apparent density percentage after sintering process
in a range (93-98)% and decrease in porosity (25- 35)% as a range also after sintering process,
which it’s a great evident that the time and temp. of sintering process chose carefully and gave
optimum properties of FGMs specimens. Mechanical tests such as Vickers microhardness, fracture
toughness and residual stresses used to characterize prepared of FGMs. All mechanical tests are
presented a gradient in results through the cross – section of FGMs specimens as expected from
the gradient of composition that shows a smooth transition from layer to another that eliminate
the sharp transition. X-rays diffraction was done to investigate phases appears and SEM and EDS
analysis also were done for AZT1, which shows higher properties among their groups, display
good distributed of 3YPS – ZrO2 from EDS analytic and there were no agglomerates, which its
good evidence of good mixing process and sintering practice.

The Design and Analysis of Nonlinear Bipolar Transistor Performance Using MATLAB is present
in this paper. The bipolar junction transistor (BJT) operation at non- linear circuit is representing a
vital part in some application. Many BJT model has been introduced such as small signal, charge
control and each model has its own area of application. The proposed model of nonlinear BJT
based on circuit of R1 and R2 set the normal operation point and small signal gain is approximately set under ration R3/R4. A decoupling capacitor of 1uF has chosen to ignore the impedance at 1
KHz to generate frequency response. Novel development used for the characteristics mechanism
replica and its performance representation of power transistor with enough memory effects is
evaluated and examined. The electrical memory effects and thermal impact on the transistor presentation is compared. The results show important information about BJT performance and proper
applications associated with each type under 45-90 OC.

This paper presents the study and evaluation of low lightweight concrete (LWC) density
production under multi stage casting process. The lightweight aggregate type and associated
volume fraction mix is determined by the lightweight concrete density. In traditional mixing
process of concrete, the minimization of the density clearly required high volume fraction
which will causes aggregate segregation. The multi stage casting procedure occupy inserting
lightweight (LW) aggregates in casing following satisfying in residual interstitial void by
means of cementations grout with a low density. Consequently, these methods produce low
compressive strength and enhanced weak point. Thus, the suggested casting technique could
have a practical for developed non-structural rudiments and structural compound that require minimum density. The results show promising methods to support many projects that
required strength more than 20 MPa for house slabs, driveways and footpaths.

The electrical and mechanical construction of cheap and simple laboratory model of electromagnetic accelerator is presented. The system was operated at low energy of about 1.5KJ, producing a projectile
velocity of about 50 m/sec. The system analysis based on a developed mathematical model shows the
.variation of the current and the velocity as a function of the time