Print ISSN: 1681-6900

Online ISSN: 2412-0758

Volume 26, Issue 12

Volume 26, Issue 12, December 2008, Page 473-1562


Study of Heat Transfer from a Sphere Body to Flowing Media

Hassanain Ali Jabber; Balasim Ahmed Abid; Abdullah Abbas Kendosh

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1439-1450

In the present research the convective heat transfer from a hollow copper sphere
(10.2 cm in diameter) to air is studied at different temperatures of sphere surface.
The experiments were carried-out in an experimental channel (245 x 48 x 50 cm)
and the velocity of air was changed by varying the orientation of the gate of the
channel which has four levels. A fan of moderate capacity generates air into the
channel.
The sphere was heated by hot water at approximately constant wall at different
measured temperatures 40, 50, 60, 70 and 80 0C and local heat transfer coefficients
were calculated. This process was done by placing ten thermocouples into the inner
surface of sphere. These thermocouples were connected to a digital reader which
gives the instantaneous temperature of a specified region. The thermocouples were
numbered and distributed in an equal angular displacement of 36 degrees.
The determination of heat transfer coefficient was done through two regions, the
first called the front region, which faces the fan, and the second called the wake or
backward region in which vortices were generated and built-up. A variance of
temperature was recognized between these two regions in such a way that front
heat transfer coefficient was higher than that for backward region.
The analysis of the present work is based on Reynolds number which is change
from 12894 to 33282 depends on the velocity of the used fan. The experimental
results of this study were compared with Kendoush analytical correlation (1995)
together with a number of certain other mathematical equations obtained from the
literature. It was found that this comparison was good especially at higher
temperatures.

Effect of Alcohol as Additives on the Morphology and Separation Performance of Polyethersulfone (PES) Hollow Fiber Ultrafiltration Membranes

Najat J. Saleh; Amel Alhelaly; Samira N. A; Qusay Alsalhy

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1451-1460

Hollow fiber ultrafiltration (UF) membranes were prepared using Polyethersulfone
(PES), alcohol (n-Propanol) as additive and N, N-dimethylacetamide (DMAc) as a
solvent. Asymmetric hollow fiber UF membranes were spun by wet phase
inversion method from 17 wt% solids of PES/additive/NMP solutions. The alcohol
additive was n-Propanol while the external coagulant was water. Effects of n-
Propanol concentrations in the dope solution on morphology and separation
performance of PES hollow fiber UF membranes were investigated. UF
membranes were characterized in terms of scanning electron microscope (SEM)
while UF experiments were conducted using polyethylene glycol (PEG20,000MW)
and poly (vinyl pyrrolidone) (PVP 40,000MW), as a solute. It was found that the PES
UF membrane morphology changed from long two finger-like structure through a
short two finger-like structure to the two void-like structure as n-propanol
concentration in the dope solution increased from 5 to 20 wt % using water as a
bore fluid; pure water permeation fluxes (PWP) increased from 47 to 201
L/m2.h.bar while rejections of PEG MW20,000 and PVP MW40,000 for wet-spun
PES hollow fiber membranes were decreased with increased of n-propanol
concentration up to 20%. Using above method, PES hollow fiber UF membrane
with high pure water permeation flux could be prepared while the molecular
weight cut-off of PES hollow fiber membranes is approximately 20,000.

Long -Term Deformation Of Some Gypseous Soils

Mohammed Y. Fattah; Yousif J. al-Shakarchi

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1461-1483

Time-dependent deformation and stress relaxation in soils are important in a variety of
geotechnical problems where long-term behavior is of concern.
Previous studies on soils showed that the magnitude of delayed compression
(creep) is controlled by compressibility and soil sensitivity in addition to
preconsolidation.
In this paper, the time-dependent behavior of gypseous soils is investigated. The
soils used in this study were brought from three locations at Al-Tar region west of Al-
Najaf city in Iraq. These soils had gypsum content of (66%, 44% and 14.8%). The
mineralogical and chemical properties of the soils were determined.
Two series of tests were performed. In the first, collapsibility characteristics were
investigated for a long period (60 days) by conducting single and double oedometer
tests. In the second series, the effect of relative density on collapse with time was
investigated. The samples were compacted to 40%, 50% and 60% relative density and
then tested. The results of collapse tests showed that the relationship between the
strain and logarithm of effective stress has two vertical lines. The first one represents
the collapse settlement taking place within 24 hours, while the second one represents
the long-term collapse. The collapse potential in both single and double oedometer
tests increases when the gypsum content increases from (14.8%) to (66%) and when
the initial void ratio increases.
The results of double oedometer tests showed that the relationship between the
collapse potential and logarithm of time, for samples loaded to 800 kPa for 60 days,
consist of three distinct segments. The first segment is represented by a curve concave
downward in which the compressibility gradually increases. The second segment is a
straight line with a higher increase in the strain. The third segment which refers to
creep collapse depends on the gypsum content. Gypseous soil with low gypsum
content (14.8%) exhibited significant decrease (5.21% at 24 hours to 7.16% at 60 days)
in collapse potential with time.

Fabrication and Characteristics Study Of CdO/Si Heterojunction

Khalid Z. Yahiya; Ammar H. Jareeze; Ammar M. Al-Baldawi

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1484-1491

In the present paper CdO/Si heterojunction has been prepared by spray pyrolysis
method , electrical characteristics include I-V , C-V , were studied the build-inpotential
equal 1.7 eV and optoelectronic characteristics include I-V illumination
condition, photovoltaic, responsivity , quantum efficiency were studied . the
ideality factor to be 2.93 and short circuit photocurrent 170μA, open circuit
photovoltge 120mV at AM1 condition and two peaks responsivity were found ,
first peak at region 600±20nm this peak due to absorb of light in CdO through
band-to-band absorption while second region at 800±30nm which due to the Si
bandgap.

Optimum Design of Single-Phase Cascade Multilevel Inverter Using OHESW Technique

K. S. Krikor; Khalid I. Alnaimi; Jamal A. Mohammed

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1492-1507

The traditional two or three levels inverter does not completely eliminate
the unwanted harmonics in the output waveform. Therefore, using the
multilevel inverter as an alternative to traditional PWM inverters is
investigated.
This paper describes the Optimized Harmonic Elimination Stepped Waveform
OHESW technique to improve the output waveform quality of multilevel
inverter fed induction motor. A new method is presented where switching
angles are computed such that a desired fundamental sinusoidal voltage is
produced while at the same time certain higher order harmonics are eliminated.
The proposed method also is used to minimize the Total Harmonic Distortion
THD of the synthesized multilevel waveform. The THD is investigated over a
wide range of possible output control voltages and number of voltage levels
used to synthesize the output waveform.
Simulation results of a cascade multilevel inverter under OHESW technique
with 5- up to 15-levels are used to eliminate the (3rd-13th) harmonics.
A prototype single-phase cascade 7- level inverter loaded by single-phase
induction motor is investigated.

Effect of Polypropylene Fibers on Properties of Mortar Containing Crushed Brick as Aggregate

Shakir A. Salih; Maha E. AL-Azaawee

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1508-1523

More recently there has been a great attention towards converting waste
materials by- products into useful materials as aggregate in concrete industry.
It is thus aimed in this study to investigate the possibility of using waste brick
as suitable materials and alternative to the natural aggregate in the production
of lightweight mortar.
The essential objective of this work is to study the mechanical properties of
lightweight mortar containing different percentages of polypropylene fiber
with high range water reducing agent. The effective synergy of this admixture
on the properties of mortars is also investigated. Compressive strength,
splitting tensile strength, thermal conductivity and drying shrinkage tests were
conducted on reference and polypropylene fiber reinforced mortar specimens
at various ages of curing (7, 14, 28, 60 and 90 days) respectively.
The results show a significant increasing in splitting tensile strength with
the increment of fibers content. Although, a considerable reduction in
workability is recorded as increasing the fiber content. Which is controlled by
using high range water reducing admixture. All mixes show acceptable values
for thermal insulation with regards to ACI 213-87 thermal insulation
recommendations.

Effect of Multi-Coats of Cutting Tools on Surface Roughness in Machining AISI 1045 Steel

Maan Aabid Tawfiq

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1523-1533

In this study, orthogonal machining tests in dry turning method are performed on
(AISI 1045 St.), in order to examine the influences for the type and number of
coatings on surface roughness. The cutting tools used are (TiN, TiN/TiC, and
TiN/Al2O3/TiC); multiple layers coated cemented carbide inserts. The tests are
performed at five different cutting speeds (80, 112, 155, 220 and 300) m/min,
while the feed rates are kept to be (0.08, 0.11, 0.14, 0.16 and 0.2) mm/rev
respectively, at constant depth of cut and tool geometry. The results showed that
(TiN/TiC) coated cutting tools gave best results for surface finish compared with
TiN/Al2O3/TiC, TiN and uncoated tool, for all the selected machining conditions.
The experimental results showed that, when the cutting speed is increased from
(80-300)m/min and feed rate is reduced by (250%), the values of surface roughness
is decreased by: (20%) for uncoated tool insert ,(27%) for single coated layer insert
(TiN), (55%) for double coated layer insert (TiN/TiC) and (49%) for triple coated
layer insert (TiN/Al2O3/TiC).

FM Mode-Locking Fiber Laser

Inmar N. Ghazi; Waleed Y. Hussein; Salam Sami M. Salih

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1534-1549

In this paper the study of Frequency Modulation Harmonic Mode-locking for
Ytterbium Doped Fiber Laser is presented. The model studied, uses ytterbium-doped,
single mode fiber pumped by 976 nm laser source is used with 150 mW pumping
power to produce 1055 nm output laser and Frequency Modulation Harmonically
Mode-Locked by MZI optical modulator. The effect of both normal and anomalous
dispersion regimes on output pulses is investigated. Also, modulation frequency effect
on pulse parameters is investigated by driving the modulator into different frequencies
values.
This study shows the stability of working in anomalous dispersion regime and the
pulse compression effect is better than counterpart normal regime, due to the
combination effect
of both negative(Group velocity dispersion), GVD and nonlinearity. Also it shows the
great effect of modulation frequency on pulse parameters and stability of the system.
Model-locking fiber laser master equation is introduced, and using the assumed pulse
shapes for both dispersion regimes after modifying (Ginzburg-Landau equation), GLE
and by applying the moment method, a set of five ordinary differential equations are
introduced describing pulse parameters evolution during each roundtrip.To solve these
equations numerically using fourth- fifth order, Runge-Kutta method is performed
through MatLab 7.0 program.

Effect of Some Processing Parameters on Arc Sprayed Coating

Ali Hussein Ataiwi

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1550-1562

In this work, arc spray coating of 13% Cr-steel (BS403S17) has been used in
repair of nodular cast iron journals. This study discusses the processing factors
effecting the roughness, hardness,and wear resistance of coating produced by
arc spraying. The studied factors are applied voltage, wire feed rate, spraying
distance (distance between gun nozzle and substrate) and coating thickness. All
coated samples were tested using pin on ring wear testing machine.
The final results showed that the best voltage in this application is between 28
and 30 V. With this voltage a reduction in wear rate of about 8% can be
obtained. The research reveals that the wear rate decreases by 46% with
increasing in wire feed rate from 68 to 122 mm/s and it is found that the best
spraying distance is about 10 to15 cm to get a good coating surfaces with
reduction by about 58% in wear rate. It is also approved that coating thickness
has positive effect on reducing wear rate by 43%.

The Effect Of Changing Iraqi Residence Building Orientation , Materials And It's Construction Position On Energy Consumption

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 473-483

The researcher was noticed that through his study for Iraqi residence
building for low income people, the big similarity of its architectural
design appearance. Therefore, he was selected one of that; he was
calculated its cooling load (heat leakage through glasses, walls and roof
areas) and its electrical energy con gumptions during 12 hours/day, 30
day/month for summer months. The researcher was changed the three
parameters and replication that calculation in each once:-
• Building orientation (the researcher assumed that building would be
constructs in eight orientations.
• Building materials (the researcher assumed that building would be
constructs with five different types of walls and roofs).
• Construction position (the researcher assumed the building area latitude
would be constructs with five position in Iraq).
At last ,the researcher found that , the good orientation for that selected
building is South East – North West , which it consumed minimum
energy for cooling purpose , and that energy that building value was
increased by 8% when rotated to North East –South West and became
15% with East – West and 23% with North – South orientations and also
, the researcher found that , the good orientation is the same even if
construction position variation , but the energy required for cooling
purpose is varied , maximum energy saving about 14% when the
construction position was replaced from Basra to al-moosel , and finally
, the researcher found also , the energy saving about 16.69% when
building materials were replaced from ordinary brick to thermoston brick
with thermal insulation material and is 34.3% when usage thermal
insulation material (5 cm thickness ) in roof.

The effect of changing internal tube diameter on the performance of uniflow vortex tube

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 524-534

In this present work, the optimum design and performance of the uniflow
vortex tube used as a cooling and heating device of high efficiency is investigated experimentally. Great attempts to reach minimizing the uniflow vortex tube size with high separation energy are investigated.
The experimental investigation was carried out on a vortex tube rig especially
designed for the present study covering all tests. Experiments were carried out on
the vortex tube by fixing (L/D) at (20) for five tubes ,four of them are straight with
diameters (30,20,15and 10) and the last is diverge tube with angle(θ=1.72°) and
length(350mm),the cone angle is (θ= 30°),consequently the study of the energy
separation performance of five uniflow vortex tubes wer carried out.
The experimental results shows that the pronounced influence of the uniflow
vortex tube (D=20mm, L=400mm) on the energy separation performance at cone
valve diameter (dc=12mm), i.e the highest temperature of the hot air stream and
the lowest temperature. The cold air stream reaches (47.5Co) at (Y=0.812) &
(2.4Co) at (Y=0.313) respectively at the inlet air temperature (Ti=33Co).
The results of the uniflow vortex tube shows that increasing the isentropic
efficiency & coefficient of performance with increasing inlet air pressure within
the range (Piabs = 2-6 bar) which reaches ηise= 24% at Y=0.753 & COP=0.14 at
the same Y. Also the result shows that refrigeration capacity & efficiency of the
energy separation increasing with increase inlet air pressure & reaches Qr=1385
watt at Y=0.704 & ηe =34% at Y=0.323.

Symbol as continuity tool in type – convention system

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 535-548

The research aims to declare the relationship between communication and
symbol architectural thoughtly construction in the within context of post modren
architecture for support research objects modernity . Symbol was very important
concept and many of thesis have declared and different about it because symbols
represented carrier components to civilizationary dimension and transportaring for
knowledge flow throughout ages and architecture one of main knowledge fields
which have basic and clear job in represent image any civilization and any identity
for any community and this what have decleared in form in theses of post modren
architecture which depend on the last trace and for decleare the importance of abasic
object research which was specailized by communication of symbol by depend
system ( the type – the convention ) .
The research came in three approach :- first aim decleare the importance of the
concept in different fields and it`s thearitical relations and finally What was about it
from contemporary architectural theses . second : aim to basicrelation ship of concept
with communication concepts to arrive basically of this relation ship third : aim
decleare symbol`s communication by depend concept of the type from throughout
decleare importance of post modren theses in crystallized a new symbolic typeis the
benefit from concept convention help in a conventional character on it for understand
and delling on content of this symbols and this which was doing main research goal
which specializes by study of relation ship between communication of symbolic types
and the benefit from convention to understand it and then final conclusions for the
research .