Print ISSN: 1681-6900

Online ISSN: 2412-0758

Volume 27, Issue 12

Volume 27, Issue 12, September 2009, Page 423-2516


Studies on Gas Hold-Up , Mass Transfer Coefficient,Mixing Time And Circulation Time In Bubble ColumnsWith Draught Tube For Pseudo Plastic (Carboxymethyl) Cellulose And Glycerol Solutions

Ali Abdul.R.N.Jasim

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2245-2256

Bubble column reactors are widely used in chemical process industries for
carrying out gas-liquid and gas-liquid-solid reactions such as absorption, biochemical
process and coal liquefaction. To design such a column, four main parameters should
by taken in consideration, the gas hold-up ( g e ), liquid phase mass transfer coefficient
(KLa), mixing time (tm) and circulation time (tc). The study includes the effect of gas
velocity and liquid phase properties [Newtonian and non-Newtonian] on g e , KLa, tm
and tc in bubble column with draught tube when the ratio of the draught tube diameter
to column diameter equal to 0.5 and the gas dispersed into the base of the draught tube
by using [amultihole, 0.15mm equivalent diameter and 0.61% free sectional area]
distributor.
Water and aqueous solutions of glycerol and CMC [Carboxymethyl Cellulose],
were used as the liquid phase [Newtonian and non-Newtonian]. From experimental
observations g e , and KLa increased with increasing gas velocity and coalescence
inhibition of liquid, while tm and tc decrease with increasing gas velocity.
It was found that increasing liquid viscosity and coalescence reduces g e and KLa
but increases tm and tc.

Combined Effect ofWheel and Thermal Load Conditions on Stress Distribution in Flexible Pavement

Zainab Ahmed Alkaiss; Suham E. Saleh Al-maliky

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2257-2267

The aim of this research is to study the behavior of flexible pavement under
wheel and thermal loading conditions using the finite element program ANSYS V
(5.4). The stress states distribution within the asphalt concrete pavement that
influence the direction of crack propagation have been investigated. The obtained
results from ANSYS finite element program show that a maximum stress intensity
factor value obtained at surface and then decrease with depth about (0.75 of
asphalt layer thickness) due to reduction in temperature in asphalt layer, which
indicates that crack will initiate at surface and extend throughout asphalt layer.
The horizontal stress for both top and bottom layers increase with the variation of
thermal coefficient expansion factor. High values of stresses at top surface of
asphalt layer due to high contact stress were induced under wheel and thermal
load conditions. As a result the highway pavement exhibited propagation of
surface –initiated cracks. Field observation of cores extracted from asphalt
concrete pavement confirmed the obtained results.

Application of a Finite Element Package for Modeling Rotating Machinery Vibrations

Farouk O. Hamdoon

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2268-2276

ANSYS has no module to analyze dynamics of rotor-bearing systems,
especially to calculate critical speeds. But it has element types, such as beam element
and matrix27 element, which can be modeled as stiffness, damping and mass matrix.
In this paper, BEAM4 element and MATRIX27 element are adopted to model the
shaft, rotating disks and bearings. Some ideas are presented to deal with critical speeds
calculation using ANSYS. The accuracy of the model and the solution technique have
been demonstrated by comparison with results of previous publications. Very good
agreement has been obtained.

Analysis Up To Failure Of Straight And Horizontally Curved Composite Precast Beam And Cast-In-Place Slab With Partial Interaction

Husain M. Husain; Mohammed J. Hamood; Alaa Adnan Hafez

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2277-2289

In this study, a nonlinear three-dimensional finite element analysis has been
used to predict the load-deflection behavior of horizontally curved composite
beams of concrete slab and I-section steel beam with shear connectors using the
analysis system computer program (ANSYS V. 9.0 2004).
A comparison is made between the results obtained from the finite
element analysis and the available experimental results. The comparison shows
good agreement. The maximum difference in ultimate loads was (13.2%).
Parametric study was performed to study the influence of several important
parameters on the overall behavior of a horizontally curved composite beam.
These parameters include the curvature (L/R) of the beam, supports conditions
and concrete compressive strength. L/R has significant influence as more and
more twisting effects will be introduced

Hydrodynamic Characteristics of a Gas- Liquid –Solid Fluidized Bed Containing a Binary Mixture of Particles

Adiba A .Mahmod; Mohammed F. Abed; Amer A. Abdul Rahman

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2290-2307

The present work is an experimental study on the effect of solid loading and
solid properties of both single and binary mixtures on the hydrodynamic parameters
(gas holdup and bubble dynamics) of a fluidized bed bubble column. The experiments
were performed in a QVF glass made column of 15 cm diameter. Wide range of solid
particle diameters (0.5 to 3mm) with two different densities
(i.e., 1025 and 1150 kg/m3 ) were investigated for the bubble effect on gas holdup and
bubble dynamics using air with different gas superficial velocities ( 3 to 9 cm/s). A
binary mixture consisting of different compositions of solid particles was prepared to
be utilized in the study. It was observed that for specified operating conditions used in
the experiments there is a proportional relationship between gas holdup and both
superficial gas velocity and particle diameter while an inverse relationship exists
between gas holdup and both solid concentration and particles density. Bubble
dynamics (i.e., bubble diameter and bubble rise velocity) is looked at from a different
view point, it increases with increasing solid concentration and with decreasing
particles diameter.

Effects of New Additives (Lanolin) on the Electro-Deposition of Copper Powder

Sami I. Jafar

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2308-2321

New organic compound (Lanolin) is added to the electrolyte of copper
powder deposition unit. The influences of the copper concentration, current
density, and specific surface on the apparent density of the produced powder had
been studied. Also the mean grain size of powder, mass of deposited powder are
been calculated. The best concentration of lanolin is 0.7% at which grain size
deposits are smooth and fine (a bout 93% less than 53 micron) and had high
purity of 99.9%.

Development and Strength Properties of PP/PA6/RED Kaoline and PP/PA6/ Bentonite Blends

Najat J. Saleh

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2322-2335

In the present work a new type of composite material has been prepared
from mixing of polypropylene and polyamide 6 at constant ratio (80/20)] and
adding different weight percent (0, 5,10,15)% of both local bentonite and red
kaoline fillers respectively by using single screw extruder .Some of mechanical
properties such as tensile strength (Young modulus) tensile at fracture and
elongation of filled and unfilled PP/PN6 blends were determined at different
temperatures, and different weight percent of filler. Addition of filler increases the
Young modulus and tensile strength at break. Bentonite filler gives better
mechanical properties, than red kaoline fillers. Also empirical equations were
obtained which could be utilizing to calculate one of the mechanical properties in
term of temperatures and weight fraction of filler content. An equation was
proposed to show the best fit with experimental data, relevant contour diagrams,
for optimization of properties is also presented.

Removal of Lead and Copper Ions onto Granular Activated Carbon in Batch and Fixed Bed A Dsorber

Abbass H. Sulaymon; Balasim A. Abid; Jenan A. Al Najar

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2336-2351

The adsorption of lead and copper ions onto granular activated carbon (DARCO
20-40 mesh) in a single component system has been studied using fixed bed adsorbers.
A film-pore diffusion model has been developed to predict the fixed bed breakthrough
curves for the two metal ions. This model takes account both external and internal
mass transfer resistance as well as axial dispersion with non-linear isotherm. The
effects of flow rate, bed height and initial metal ion concentration has been studied.
Batch adsorber experiments were conducted to estimate the parameters required for
fixed bed model, such as adsorption equilibrium isotherm constants the external mass
transfer coefficient and pore diffusion coefficient by fitting the experimental data with
theoretical model. The batch isotherm experimental data was correlated using
Langmuir and Freundlich isotherm models. The adsorption isotherm data follow the
Langmuir model better than Freundlich model. The pore diffusion coefficient was
obtained using pore diffusion model for batch adsorber by matching between the
experimental data and predicted data from the model. The results show that the filmpore
diffusion model used for fixed bed adsorber provide a good description of the
adsorption process for adsorption of metal ions Pb(II) and Cu(II) onto activated carbon
in fixed bed adsorber.

Modeling of Shear Strength in Rectangular Reinforced Concrete Beams

Hussein A. Azeez

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2352-2366

In this paper a model for the shear capacity of rectangular reinforced
concrete beams is proposed. This modeling depends on statistical analysis for 101
experimental results from literatures, as will be indicated. These results are pure
shear results and shear resistance is predicted by concrete only (without shear
reinforcement).
The ACI approach for predicting shear strength as the sum of diagonal cracking
and 45◦ degree truss model predicts the shear strength of beams, with an average of
experimental to predicted shear strength ratio of 1.4 with a coefficient of variation
of 46.7%.
In this study, experimental pure shear test results as much as possible are revised to
study the shear behavior and then modeling it using statistical analysis, to reduce
the ratio and coefficient of variation. This model gives average ratio of 1.003 and
coefficient of variation of 20.90%.
Also in this study, all the factors effecting shear capacity are introduced with
separate modeling. These factors are, concrete compression strength (fc'), beam
width (b), size of aggregate (da), shear span to depth ratio (a/d), and percentage of
longitudinal reinforcement.
Then assembly model for shear strength containing all these factors is presented
and compared with experimental results.

Optimization of Cyclic Oxidation Parameters in Steel-T21 for Aluminization Coating Using Taguchi-ANOVA analysis by MINITAB13

Abbas Khammas Hussein

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2367-2384

The increasing demands for high quality coatings has made it inevitable that
the surface coating industry would put more effort into precisely controlling the
coating process relative to media for which is subjected. Statistical design of
experiments is an effective method for finding the optimum cyclic oxidation
parameters for aluminization coating. In the present investigation, an attempt is made
to produce high-quality aluminization coating by optimizing the cyclic oxidation
parameters following a (L9-33) Taguchi-design approach. (L9-33) Taguchi orthogonal
array has been used to determine the signal to noise ratio (S/N). The oxidation
parameters that were varied include the Temperature (600,700,800oC), Time
(15,20,25hr at 5hr cycle) and Media (Air,CO2,H2O). The coating characteristics were
qualitified with respect to parabolic oxidation rate constant (KP). The performance of
the coating was qualitatively evaluated using cyclic oxidation testing. Analysis of the
experiments using Taguchi method indicated that 800oC,25hr and CO2 media are to be
the optimum cyclic oxidation conditions for pack aluminization. The contribution of
each of these parameters to the parabolic oxidation rate constant (KP) was determined
employing an analysis of variance (ANOVA) and the effect of the level of each
parameter was determined using Taguchi analysis. ANOVA results show that
temperature and media are the parameters that most significantly affect the parabolic
oxidation rate constant (KP) compared to time.

Ethanol Bioproduction in Three-Phase Fluidized Bioreactors

Haiyam Mohammed A. Al-Raheem

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2385-2397

In the last decade bioalcohol has become more and more important as an alternative
energy source and chemical feed stock. Bioethanol production has been proposed as a
gasoline enhancer to reduce greenhouse gases, gasoline imports, and to boost the economy.
Circulating fluidized beds (CFB) have been used in a variety of industrial processes due to
their distinct advantages of uniform temperature distribution, high gas-to- particle mass and
heat transfer rates and flexible operation.
The present study deals with the experimental analysis of the circulating fluidized bed
reactor, which is applied to the fermentation of glucose to ethanol. The study takes into
consideration the presence of three different phases; yeast (solid) which is continuously
fluidized by the liquid stream (glucose solution), and the gas bubbles which greatly enhance
mixing and the wake phase which follows tracks of the gas bubbles. The reactor
performance is analyzed as a function of major operating conditions, the yeast mass in the
reactor (30-150gm/l), the concentration of glucose in feed (10-150gm/l), reaction
temperature (15,25,30,36,37, and 40ºC) , and velocities of gas and liquid feeds (0.01-0.1m/s).
The results indicate that high glucose conversions can be obtained at high gas velocities, low
liquid velocities, high yeast concentration, and an optimum operating temperature of 36oC.

Retrofit of Shear Critical R.C. Beams with Carbon Fiber Reinforced Polymers (CFRP)

Kaiss F. Sarsam; Amer F. Izzet

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2398-2410

This paper presents results of an experimental investigation involving eight
tests on 1800mm long reinforced concrete (RC) beams strengthened in shear with
externally bolted carbon fiber reinforced polymer (CFRP) composites. The overall
objective of this study was to investigate the shear performance and failure modes
of RC beams strengthened with externally fixed carbon FRP (CFRP) manufactured
U-warp strips and the specific goal was to keep the CFRP strips working till the
beam reaches its flexural failure because in most of the previous researches the
CFRPs debonded from the concrete surface and the failure (separation) happened
in the concrete. The variables investigated within this program included: CFRP
spacing and number of CFRP layers. The experimental results indicated that the
contribution of externally fixed CFRP strips to the shear capacity is significant and
depends on the variables investigated. In all the beam specimens (with end
anchorage) the debonding was not observed.

Evaluation Study of Alexander And Abramowicz Absorption Energy Models Using Thin Metallic Tubes

Ayad Aied Mahuof; Wisam A. bdul-latif; H. J. Mohamd Al-alkawi

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2411-2424

To estimate the models of Alexander and Abramwicz Aluminum alloy AISI
5052 tubes specimens are used under impact loading and room temperature. Two
types of specimens are used the circular and square cross – section tubes with equal
wall cross – sectional area. The main conclusions that can be drawn from this
work are as follows :
-This study showed that the models of Alexander and Aromawicz are valid for the
aluminum alloy.
-.The circular section specimens absorbed energy greater than the square cross
section specimens

Optimization of Asphalt Mix Improved by the Addition of Scrap Tires

Raghad O. Abass; Mohammed O. Abass; Falak O. Abass

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2425-2446

The design of improved asphalt mix is achieved by the use of three major
variables , weight of scrap tires replaced by coarse base aggregate , particles size of scrap tires finally the weight of binder used (bitumen). The improved asphalt mix (IAM) requires a balance between rut
resistance and durability to resist cracking and moisture damage (stripping) .Accordingly several factors that influence rut resistance and durability are considered during the design process: The mix consisted of binder (3.0-6.5) %wt. , scrap tires (10-30) wt% with
particle size of (1-5) cm , is achieved by the application of box-Wilson design program. The improved mix is achieved by the use of both hot (wet) and cold (dry) processes for preparing the standard mix firstly under high temperature 168˚C with a continuous mixing for 2 hours then mould this hot mixture in standard molder found with the replacement of a coarse percent of aggregate by the different sizes of scrap tires (1-5)cm by the use of cold ( dry) technique , finally a
compression step is achieved with 52 hut for 20 min for both sides of molder in order to compress the prepared specimens then leaved for 24 hrs from the stability of specimens before any tests applied .
The results of selected variables are studied for prepared specimens to
check different important properties (mechanical, physical, chemical, thermomechanical and thermo-physical properties), then applied these result properties data in analytical computer programme software to check its fitting to design model selected and calculated the optimum properties and optimum variables for improved asphalt mix. After-ward the computerize analysis results shows that an optimum mix No.(11) reached high stability and flexibility, also gave excellent physical and
chemical properties as shown in present work below. Also described in this work the application and comparison between standard and improved optimum asphalt mix.

A Proposed Algorithm for Reactive Power & Voltage Coordination in Distribution Systems Using Fuzzy Technique

Aws Habib Mohammed; Afaneen Anwar Al-Khazragy

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2447-2464

This method finds the Under Load Tap Changer (ULTC) position and
capacitor ON/OFF status of each hour for the next day in main or secondary
distribution substations, so the secondary bus voltage improves and the reactive
power flow into the transformer can be restrained at the same time. The only
condition to achieve these goals is the previous knowledge (by forecasting) of
load demand for active and reactive power and the primary bus voltage for each
hour of that day. The practical constraints are involved through the use of
membership concept in fuzzy set theory, where these constraints are bus voltage
limits, the tolerable worst power factor & the maximum allowable number of
switching operations for the Load Tap Changer (LTC) and capacitor in a day. This
method is also considering the variation of load active & reactive power with its
voltage, where the loads are classified into three categories according to their
relationship with voltage, and so there are constant impedance loads, constant
current loads and constant power loads. To demonstrate the usefulness of this
method an example on one of the Iraqi national grid substations (132/33KV
Yarmook substation) was made in MATLAB.

Design and Implementation of Free Space Simplex Video – Laser Communication system

Labeab O. A. Ghani; Ridha Salih; Hyder Abdul

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2465-2478

The optical communication system consists of a transmitter uses a laser beam of
a wavelength 650 nm as a carrier in free space, and a receiver uses PIN diode as a
detector . In both sides Intensity modulation (IM) technique has been used to transmit
video signal of a frequency range (0~5) MHz band width. The video signal fed by
camera. The transmitted signal amplified and converted to a modulated intensity of
laser beam and sent to the receiver, the receiver converts the laser signal to a weak
electrical signal by the detector; the signal will be amplified and converted back to an
analogue signal to produce the original transmitted signal, and monitored by TV set in
(black and white ) . The transmission range was 5 m , that can be developed letter for
longer range.

Preparation Of Al-12si Foam Using Liquid Technique

Adel Mohammad Jaber; Nawal E. Abdullatef

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2479-2493

This research aims at foaming an Al-12Si alloy by using CaCO3 powder
as a foaming agent added to the agitated melt in different weight percents.
The foaming process was carried out at different foaming temperatures of
700C˚, 750 C˚ and 800C˚ for 5, 10 and 15 minutes using different foaming
agent percents (0.5, 1, and 1.5) wt%. The metallic foam had been
characterized by microstructure examinations, density and porosity and
compression tests.
It was found from the results that there is an ability to produce metallic
foams based on Al –Si alloy by using CaCO3 as a foaming agent without the
need for adding ceramic stabilizing materials which are always added in a
high percent. The mach inability problems caused by the presence of these
materials can therefore be avoided.
It was also pointed out that the porosity of metallic foams fabricated in
this work increased as the foaming agent percent increases within the range
used (0.5% - 1.5 %) and the preferred amount is 1%, where the optimum
foaming time is 10 minutes at a foaming temperature of 750 C˚.

Represent Different Types of Sliding Mode Controllers by VHDL

Mohammed H. Khudair; Ekhlas H. Karam; Yousra Abd Mohammed

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 2494-2516

This paper focus on represent and implementation the conventional sliding mode control (SMC), in addition to some types of the common enhancement SMC approaches using reconfigurable hardware technology based on Field Programmable Gate Arrays (FPGAs); this is because FPGAs are highly attractive options for hardware implementation. The enhancement SMC approaches that used here are:1) the conventional SMC with boundary layer, 2) PI sliding mode controller, and 3) boundary SMC with new approximation sign function. The main key of this work is to
implement these SMC approaches in high volume FPGA devices, a low area and fast clock speed device, where these approaches are implemented in Xilinx Vertix family Xcv1000-fg680-4 FPGA (the occupation rate is 86% and maximum net delay is 0.032 ns). All the architectures in VHDL, verified the functionality using Active-HDL simulator, and synthesis the data paths using ISE 4.1i software package synthesis tool
and Xilinx place and route tool of this package. Finally, to test the performances of the enhancement SMC approaches, computer simulation is performed on linear and nonlinear system models in order to compare the performance of these SMC approaches to illustrate which approach between them give more efficient performance than the others

Study The Reasons for The Increase in The Proportion of Damage in The Dry Clay and The Phenomenon of Effloresce for Pottery Brick

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 423-437

Given the emergence of cracks in a high proportion of clay product in the production phase of the plant Blocks in the laboratory Abu- Nuass which was reflected in the increase of damage from the permissible limits, as well as the high proportion of soluble salts that are on the external surfaces of the product, which negatively affect the properties of bricks in the future lead to the break in the walls
and turned into a fragile strength, which affects the safety and durability of origin and to address these negative phenomena and to identify causes and improve the properties of brick products to be within the specification has been adopted for this research and to take practical steps in the development of a scientific program for
the follow-up stages of the process of production and make the appropriate adjustments to it, starting with the initial article and the semi-final and ending with the product. The focus was on developing a program to modify the conditions of drying and burning and the adoption of the drying period of time not exceeding 72 hours and a
gradual manner to control on the stresses generated by the sudden evaporation of water. As well as kaolin’s clay been added to the soil and in different proportions were different burning temperature was reached by adding the best results (30- 40)% of kaolin’s clay degree burn (950-1000) m into the soil and following the step-by-step method of drying, where it was observed a significant improvement in the properties of bricks in terms of strength and absorption of water and effloresce phenomenon.

Study of Design and Implementation Factors That Leads to the Increase of Project Cost Risks During Construction Stage

Engineering and Technology Journal, 2009, Volume 27, Issue 12, Pages 438-452

The study of design and implementation factors that leads to the increase of the cost risks during the construction phase is considered as one of the basic rules for the successful task and that will lead to control the cash flow through the construction. There is an attempt in this research to follow up the effective factors on cost risks like the effect of layouts and designs preparing also the effect of contracts types and other factors and its combined impact on real fundamentals
of cash flows and to avoid the differences which may be occurs due to
misunderstanding or any confusion between the contract parties, specially in payments paid by the project owner to the contract. The research includes the field survey which depended on questionnaire that prepared in significant manner and distributed to different parties which have a scientific and practical experiences on projects. The research conclusion pointed out that design requirements is the
major influencing factor that represent (80%) of the project cost overrun risk and then come the other factors having lower values of effect.