Print ISSN: 1681-6900

Online ISSN: 2412-0758

Volume 26, Issue 8

Volume 26, Issue 8, August 2008, Page 324-1054


A Novel Deployable Open Ends Support Reflector

Adnan D. Mohammed; Adnan D. Mohammed; Muhsin J. Jweeg

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 894-906

This paper presents an improved deployable reflector concept for an Earth
observation mission that requires a low-cost L-band Synthetic Aperture Radar
(SAR) satellite. The required reflector shape is an offset parabolic cylinder with an
arc length of 7.888 m and a width of 3.2 m. A novel hollow solid structural
concept is proposed that comprises curved surfaces formed from thin sheets of
carbon-fiber-reinforced-plastic (CFRP) connected by flexible hinges along the
edges. This proposed structure has very high stiffness-to-weight-ratio, because of
its thin-walled box-type construction. A preliminary design of the full-scale
structure in deployed configuration, which has an estimated mass 22.5 kg and
18.665 kg and fundamental natural frequency of 0.72 Hz and 0.64 Hz before and
after the optimization analysis respectively, is presented in the paper. This is 3.5 to
4.2 times lighter than the traditional reflector structure, made from lightweight
curved panels with self-locking hinges. A detailed study of a quarter-scale
technology demonstrator made of 0.6mm thick thermoplastic (nylon), including
design, manufacture and testing is also presented.

Application of Artificial Neural Network In Cathodic Protection of Carbon Steel Pipe In Sea Water

Sami Abulnoun Ajeel; Ghalib A. Ali

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 907-918

The intelligent techniques are used successfully in a broad band of applications
one of these applications is the cathodic protection system. Examples of these
techniques used in cathodic protection are fuzzy logic and genetic algorithms. The
present work aims to use the neural network to predict the minimum current
density required in impressed current cathodic protection to protect low carbon
steel pipe which have been related previously.[1].
This work deals with choosing the best network architecture for cathodic
protection system. This step used multilayer feed forward network four
environment variables (concentration C%, temperature T, distance D and pH) as
input to identify the minimum current density as output in a feed forward network
structure with one hidden layer using the practical results data for the learning
process. The best number of neurons in the hidden layer is chosen by trial and error
and it is found to be 25 neurons. the decision function used is the tan training
algorithm with one variable learning rate. Then, neural network training is done
using 25 data samples from the experimental data for the current density in the
above four variables conditions. The stopping criterion for training was to obtain a
sum square error of 0.001 or read 10000 Epochs. An (SSE) than 0.001 were
obtained after 5226 Epochs.
Generalization test used 5 data samples taken from the experimental results
other than those data samples used in the learning process to check the
performance of the neural network on these data. The SSE for these samples was
0.0053 and it shows a good generalization results for our application. The
comparison between the actual experimental output and the neural network out put
after the learning process are almost identical which indicates that good learning
process was achieved.
The practical results indicate that neural network system can be used
successfully to obtain minimum cathodic protection current density to protect low
carbon steel pipes.

Diffusion of various liquids to tubular shaped fiber reinforced composites

Hussein Ali Hamid AL-Abdly; Najat j. Salah; Adnan A. AbdulRazak; Hassen Sh. Majdi

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 919-937

In present work tubular –shaped fiber reinforced composites were
manufactured by using two types of resins ( Epoxy and unsaturated polyester) and
separately reinforced with glass, carbon and kevlar-49 fibers (filament and woven
roving), hybrid reinforcement composites of these fibers were also prepared. The
fibers were wet wound on a mandrel using a purposely designed winding machine,
developed by modifying an ordinary lathe, in winding angle of 55° for filament.
Various liquids were allowed to diffuse into the composite samples, where all
composite samples were immersed in water, HCl (0.5N, IN) and NaOH (0.5N, 1N).
The exhibited behaviors were mainly explained in accordance to Fick’s –law.
However, there were few case of anomalous behavior observed.
The observed difference in diffusion rate for acidic and basic solutions
may be explained in terms of different permeability of OH- and H+ ions in the
composite samples. This permeability was also found to be affected by the
debonding process which might be initiated by the liquid penetration. Diffusion
coefficients were also deduced and their relatively higher values are indicative for
some damage mechanism taking place in the composite and not the pure matrix.
UP composite exhibited higher values than EP composite which suggest that higher
damage has taken place in UP-composite.

Properties of Inclined Silicon Carbide Thin Films Deposited By Vacuum Thermal Evaporation

Khalid Z. Yahiya; Ammar H. Jraiz; Najem Abdu Al-Kazem

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 938-943

In this work, thermal evaporation system was employed to deposit thin films of SiC on
glass substrates in order to determine the parameters of them. Measurements included
transmission, absorption, Seebak effect, resistivity and conductivity, absorption coefficient,
type of energy band-gap, extinction coefficient as functions of photon energy and the effect
of increasing film thickness on transmittance. Results explained that SiC thin film is an ntype
semiconductor of indirect energy and-gap of ~3eV,cut-off wavelength of 448 nm,
absorption coefficient of 3.4395x104cm-1 and extinction coefficient of 0.154. The
experimental measured values are in good agreement with the typical values of SiC thin
films prepared by other advanced deposition techniques.

An Approach For Forming Spur Gear Tooth Profile

Safaa H. Abdulrahman; Adnan D. Mohammed

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 944-957

Due to high working speed requirement in industry of rotating components, gear
design development become quite noticeable and rapid in the vicinity of engineering
parameters which become to have a large effect on its performance. In this work the spur
gear of straight tooth is chosen because of its wide usage in industry, also an equation
for joining the involute profile and fillet curve is generated. Variation effect on the shape
of tooth profile forming is studied. A suggested method for generating tooth profile is
obtained and a computer program is written for drawing the involutes and trochoid
curves. The results obtained from the new method are the true continuous involute and
trochoid curves in comparison with those obtained from Mechanical Desk software
which are approximated curves fitted results.

Hydroxyapatite Coating Improved Corrosion Resistance of 316L Stainless Steel Used For Surgical Implants Applications

sami Abualnoun Ajeel; Nabeel Alawi kadhim

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 958-970

Incidences of failure of stainless steel implant devices reveal the occurrence of
significant localized corroding pitting and crevice corrosion. To reduce corrosion and
achieve better biocompatibility, the alloy of stainless steel was coated by hydroxapatite
(HAP) by electrphoretic depositing method.
The study involves modified surface of 316L stainless steel by coating it with
hydroxyapatite by electrophoretic deposition. The method was carried out in various time
intervals (from 1 to 5 minutes) at constant potential of 60 V. The electrochemical behavior
of 316L stainless steel (uncoated and HAP coated specimens) was studied in simulated
human body environment. Synthetic blood plasma was utilized for simulated body fluid
conditions.
The corrosion parameters obtained from open circuit potential and potentiadynamic
polarization for the specimens indicate nobler shift in the polarization parameters, OCPtime,
corrosion potential (Err) and corrosion current density (Icorr), for all coated specimens
in comparison with the uncoated specimen. The final corrosion results for the alloy indicated
that the specimen coated for 3 minutes was found to be more noble and have optimum
corrosion properties compared with the other coated specimens.

Mathematical Modeling of Conversion CO To CO2 in Batch Mode CO2 Laser System

Adawiya J. Haider; Duha S. Ahmed; Hind J. Jawad

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 971-975

The oxidation of carbon monoxide CO over supported noble metal catalyst is an
important part of the catalytic control in sealed-off TEA CO2 laser system. In this model,
the activities of supported noble metal catalysts (Pt/Al2O3 and Pd/Al2O3) separately in
removal CO as CO2 gas phase are studied at isothermal conditions. A batch equation is used
in this model to study the effect of reaction rate parameter k (sec −1 ) on conversion processes
at contact time t =2500 (sec) and to control the path of gases from and the reactor cavity to
indicate the effect of contact time. These results are confirming that the dissociated gases are
removed by using catalysts to regenerate CO2 molecules during the electrical discharge.

Design of Free – Form Planar Closed Curves Using Four Point Interpolation

Wissam K.H; Hussam L. Alwan; Bushra B. Abd Alhassan

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 976-985

It is desirable to construct a free-form closed curve, since large numbers of
mechanical elements follow these curves. In this work we present a parametric
interpolation for construction a free form closed curves using four point interpolation
technique. The problems and solutions approach for closing open or disjoint curves is
demonstrated taking C1 continuity as a criterion for the solution of these problems.
When the coordinates of any number of control points are introduced, the proposed
algorithm constructs and closed the intended curve. The designer is free to vary and
manipulate these control points to change the shape of the desired curve.

Starting Performance Analysis of Single-Phase Capacitor Motor Using Finite Element Method

Krikor S. Krikor; Dhari Y. Mahmood; Maha K. Yousif

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 986-994

This paper presents the starting performance analysis of the single-phase capacitor motor
and the effect of motor capacitor on the starting performance. The analysis approach is based
on 2-D finite element method for the transient case, with the software (ANSYS V.8). The
validity of the proposed analysis method is verified by experimental values which are found
to be in good agreement.

Electrical Characteristics of Silicon p-n Junction Solar Cells Produced by Plasma-Assisted Matrix Etching Technique

Oday A. Hamadi; Ban A.M. Bader; Afnan K. Yousif

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 995-1001

In this work, plasma-induced matrix etching technique was used to fabricate p-n junction
solar cells and their electrical characteristics were studied. Results showed reasonable
improvement in solar cell characteristics when compared to the characteristics of the
cells fabricated without etching process or by conventional thermal evaporation
technique. The maximum conversion efficiency of the fabricated cells was about
(2.15%) at irradiation power of (90W/cm2) and the fill factor was (56.90%).
الخصائص

Dynamically Loaded Analysis of The Adjustable Hydrodynamic Pads Bearing

Muhannad Z. Khelifa; aibel; Ali H. Z; Haider Kh.Mehbas

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 1002-1015

This paper presents the instantaneous journal center velocity under dynamic load
for adjustable hydrodynamic four pads bearing. The velocity is calculated by mobility
method in different values of length - diameter ratios (0.25, 0.5, 0.75 and 0.95). Finite
difference method was used to solve the Reynolds equation in two dimensions. This
equation includes the total oil film thickness (oil film thickness and elastic deformation
pad material due to generated pressure ).The effects of many parameters were studied
such as dynamic coefficients (stiffness and damping coefficients) and power loss on the
bearing performance. The results proved that the journal center velocity and mobility
components is affected by the sign of the eccentricity ratio components, also the
maximum value of the journal center velocity is determined by the values of the length -
diameter ratios. The vertical stiffness coefficient (Kyy) and damping coefficient (Cyy)
increase as the eccentricity ratio increased. The power loss were found increase when
length diameter ratio increase.

Factors Affecting the Relationship Between Total Porosity and Electrical Resistivity for Concrete Repair Materials

Maan Salman Hassan

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 1016-1024

The paper examines the properties of five different types of repair and substrate
materials, including conventional mortar, fly ash mortar, silica fume mortar, conventional
concrete substrate, and high-performance concrete substrate materials. Assessment was
carried out on the basis of some physical properties (total porosity, and electrical resistivity).
These properties were measured at early age and later after 14 weeks of exposure conditions
to 6 % (by weight) of sodium chloride solution to simulate typical marine environment.
The results show that the electrical resistivity and total porosity measurements appear
to be related and the measurements obtained are affected by the pore structure of the
materials. It is also expresses that if a material has grater proportion of coarse aggregates (e.g.
the substrate concrete in this study) it will appear to have a lower porosity although the
porosity of mortar surrounding the aggregates could be higher. This makes comparisons
between materials containing different aggregates proportions and size difficult.

Mathematical Model For Estimation of Desublimated Solid Layer Thickness and Surface Temperature

Wameath Shawki Abdul-Majeed

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 1025-1035

The thickness of the desublimatd solid layer is an important parameter required for
evaluation of such desublimation process, especially in the case of solid layers production
needed for special applications. A mathematical model has been derived based on the
analogy of heat and mass transfer to calculate the solid layer thickness of the desublimated
layer during the operation period. The prediction of thickness from the derived model is
based on the data related to the applied experimental conditions as well as the physical
properties of the vapour-gas mixture inside desublimator. The calculated thickness from the
model has been used to calculate the temperature gradient of the solid layer surface during
the run period.

Properties of High Performance Mortar Using Local Additives

Husain M.Husain; Zain A. Raouf; Wasan I. Khalil

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 1036-1054

High performance mortar can be produced by using ultrafine particles and superplasticizer
admixtures which reduce water – cement ratio (less than 0.3). In this investigation an attempt
was made to examine the possibility of replacing a part of weight of sand (10 and 20%) or a
part of weight of cement (11.5, 17 and 23%) by low cost locally feldspar powder (FP) without
impairing the high strength characteristic of the mortar. The experimental work includes the
preparation of the feldspar material as one type of pozzolana, and selection of high
performance mortar mix. Finally the properties of the selected mortar (compressive strength,
modulus of rupture, density, pulse velocity, static and dynamic moduli of elasticity) at room
temperature at 3, 7, 14, 28, 60, 90 and 180 days and after exposure to high temperatures in the
range from 150 to 900°C at age 60 days were investigated.
The results show that the incorporation of 17% of feldspar powder as a partial replacement of
cement and 4% of superplasticizer by weight of cement to 1:1 cement to sand mortar mix
enabled the production of high performance mortar with compressive strength of about 80
N/mm2 at 28 days. This mix shows significant drop in compressive strength and modulus of
rupture of about 45 and 60% respectively, while the reduction in static and dynamic moduli
was about 66 and 86% respectively after exposure to 600°C.

Study the effect of the chemical heat treatments on mechanical properties steel (40 Cr)

Engineering and Technology Journal, 2008, Volume 26, Issue 8, Pages 324-334

This work deals with improvement of the mechanical properties of low alloy steel (DIN 40
Cr) using surface thermochemical heat treatments ,Carbonizing, Nitriding, and
Carbonitriding. Carborizing processes were performed at 900 – 950 Cº for 3hrs. Nitriding
processes were performed at 570Cº for 1.5 hrs. Carbonitriding processes were performed at
840 Cº for 3hrs. Some specimens were oil quenched at 860 Cº followed by tempering at 500
Cº. The microstructure, tensile, hardness, and impact tests were measured. The results
showed that Carbonizing, Nitriding, and Carbonitriding processes caused improvement of
mechanical properties of low alloy steel. However specimens that were subject to quenching
and tempering had better mechanical properties than specimen that were subject to
carbonizing, Nitriding, and carbonitriding.