Table of content

Journal of Engineering

مجلة الهندسة

ISSN: 17264073
Publisher: Baghdad University
Faculty: Engineering
Language: Arabic and English

This journal is Open Access

About

The Journal Engineering was issued in 1986. It was Stopped from 1990 – 1997 because of the economic blockade. It restarted publication after the fourth scientific engineering conference for it published the papers that were accepted in the conference.
It is a scientific engineering journal refereed by specialized and qualified professors in most of the engineering fields and those Specialists in the issued by the college of Engineering university of Baghdad .It was serenely publibued , but from 2011 it has issued of monthly for the numerous papers submitted to the journal to publish their papers in this scientific journal in addition to some of the Arabs professors because the journal is considered one of the valued journals in the Arabic homelan .
Many professions were the head editor of the journal from its first issue. The first one was prof.dr. Laith Ismail Namiq then prof.dr. Mohammed A.Alawis ,prof.dr.Ali A Al – kilidar prof.dr. Abdul-Ilah Younis and currently Prof.dr.Qais S. Ismail.

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Iraq
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Email: joengbag@uobaghdad.edu.iq

Table of content: 2007 volume:13 issue:3

Article
Removal Method Assessment Through Reduction Algae Count in Uncovered water Reservoir
طرائق الازالة في تقليل اعداد الطحالب في مياه الاحواض المكشوفة

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Abstract

The Algae is considered as one of the major causes of some serious problems that occur in water plants, rivers, lakes and irrigation channels. Those problems are the unpleasant taste and odor, the clogging of waterways, and others. Hence, the algae existing extensively in any water body is considered as an obvious indication of surface water pollution. Chemical control methods were used in this research for reducing the turbidity and Algae in the laboratory using the (Jar Test). This was done by using chemical materials like Alum with concentration (10-50 mg/l). The percentage of the reduction in the algae was (95%) and in turbidity (94%). It is shown also that when using KMnO4, CuSO4 and Cl, each separately after adding the ideal dose of alum found before, will reduce the turbidity with ( 95% ,79.3% .95%) and algae removal of (99.2%, 100%, 99%) respectively.


Article
Natural Convection from Single Finned Tube Immerrsed in a Tilted Enclosure

Authors: Hadi R. Roomi --- Ikhlase M. Fayed
Pages: 1585-1600
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Abstract

Heat transfer rates of a single horizontal finned tube immersed in water –filled enclosure tilted at 30 degrees are measured .The results serve as a baseline case for a solar water heating system with a heat exchanger immersed in integral collector storage. Tests were made with both adiabatic and uniform heat flux boundary conditions. Natural convection flow in enclosure is interpreted from measured water temperature distributions. Formation of an appropriate temperature difference that drives natural convection is determined .Correlations for the overall heat transfer coefficient in terms of the Nusselt and Rayleigh numbers are reduced to the form Nu = 0.716 Ra^0.247 for 2*10^5 <= Ra <= 2*10^7 Based on the diameter of the immersed tube .Comparison the present work results with others gave a good agreement.


Article
Developing Compressible Turbulent Flow and Heat Transfer in Circular Tube with Uniform Injection or Suction

Authors: Adil A. Mohammed --- Ayad M. Salman --- Ihsan Y.Hussain
Pages: 1602-1621
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Abstract

In the present work , a numerical study has been made for the developing compressible turbulent flow and heat transfer in circular tube with uniform injection or suction. The study included the numerical solution of the continuity, momentum and energy equations together with the two equations of the (k-ε) turbulence model, by using the Finite Difference Method (FDM). The air was used as the working fluid, and the circular passage was composed of tube with diameter (20.0) cm , and the length was 130 (hydraulic diameter) .The Reynolds number of the flow was (Re=1.78x106), and the Mach number (M=0.44) the ratio of the transverse velocity at the wall (vw) to the axial velocity at inlet (Uin), Ω=(vw/Uin), for suction equal(0.001) and for injection (-0.001).. The wall of the tube was heated with constant wall temperature (Tw) and in other case with constant heat flux (Qw) as a thermal boundary condition. The development of both hydrodynamic and thermal boundary layers occurs simultaneously. The computational algorithm is capable of calculating the hydrodynamic parameters such as the velocities , friction factor , turbulence structure which includes the Reynolds stress and the turbulent kinetic energy and eddy viscosity. Besides, the thermal parameters are also predicted, such as the temperature, Nusselt number, and the turbulent heat fluxes.The Results showed that the hydrodynamic and thermal entrance length is increased with the increasing of Reynolds number. The suction caused a flatten for the velocity profile and thus decreasing the hydrodynamic entrance length, and caused an increase in the Nusselt number and decreasing the local coefficient of friction, but injection caused a steeping of the velocity profile , and thus increasing the entrance hydrodynamic length and caused a decrease in the Nusselt number and increase the local coefficient of friction. Turbulent kinetic energy and turbulent heat flux are decreased with suction and increased with injection .Predictions have been obtained which are in good agreement with results obtained by past experimental and theoretical work


Article
Analysis of Galvanic Corrosion under Mass Transfer Controlled Conditions

Authors: Basim O. Hasan --- Qasim. J.M Slaiman
Pages: 1623-1636
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Abstract

Because of practical importance of protecting industrial equipments from galvanic corrosion, the need arises to analyze the effects of variables, such as temperature, velocity, and area fraction of metals on galvanic corrosion in systems under mass transfer control as in seawater (pH=7). For these reasons the galvanic corrosion of Fe-Zn is analyzed to study the influence of Reynolds number, temperature, and area fraction on the galvanic corrosion rates and galvanic corrosion potential under mass transfer control. It is found that galvanic corrosion rate of more active metal (Zn) is increased with Reynolds number while the corrosion rate of more noble metal (Fe) is slightly increased with Re depending on the galvanic potential that depends on the area fraction. Increasing Reynolds number shifts the galvanic potential to more positive values. Also increasing temperature leads to shift the corrosion potential to more negative values and to change the corrosion rate of more active metal (Zn) depending on two parameters oxygen solubility and oxygen diffusivity. As area fraction of more active metal (Zn) increased the galvanic potential is shifted to the negative anodic direction while the corrosion rate for more noble metal is decreased.


Article
Slantlet Transform-Based OFDM Scheme

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Abstract

Wireless digital communication is rapidly expanding resulting in a demand for systems that are reliable and have a high spectral efficiency. To fulfill these demands OFDM technology has drawn a lot of attention. In this paper a new technique is proposed to improve the performance of OFDM. The new technique is use the slantlet transform (SLT) instead Fast Fourier transform (FFT) in order to reduce the level of interference. This also will remove the need for Guard interval (GI) in the case of the FFT-OFDM and therefore improve the bandwidth efficiency of the OFDM. The SLT-OFDM is also better than wavelet packet (WP)-OFDM in the selective channel because the slantlet filter bank is less frequency selective than the traditional DWT filter bank, due to the shorter length of the filters and SLT algorithm is faster than WP algorithm. The main results obtained indicate that the performance of SLT-OFDM is better on average by 18dB in comparison with that of FFT-OFDM flat fading channels. For frequency selective fading channel the SLT-OFDM performs is better than the FFT-OFDM on the lower SNR region, while the situation will reverse with increase SNR values.


Article
The Migration of Light Organic Liquids in An Unsaturated-Saturated Zone Of The Soil

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Abstract

A one-dimensional finite difference model for the simultaneous movement of light non-aqueous phase liquid (LNAPL) and water through unsaturated-saturated zone of the soil in a three fluid phase system with air assumed constant at atmospheric pressure is developed. The flow equations described the motion of light non-aqueous phase liquid and water are cast in terms of the wetting and non-wetting fluid pressure heads respectively. The finite difference equations are solved fully implicitly using Newton-Raphson iteration scheme. The present numerical results are compared with results of Kaluarachchi and Parker (1989) and there is a good agreement between them. The present model can be used to simulate various transport problems in a good manner. Results proved that the maximum LNAPL saturation occurred below the source of the contaminant during LNAPL infiltration. During redistribution, the LNAPL saturation had a maximum value at the advancing of the LNAPL infiltration front.


Article
Numerical Investigation of Laminar Natural Convection in Rectangular Enclosures of Porous Media

Authors: Selah M. Salih --- Majid H. Majeed --- Ala'a A. Mahdi
Pages: 1666-1677
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Abstract

In this investigation, steady tow-dimensional natural convective heat transfer in rectangular porous cavity, (heated from below) with horizontal walls heated to uniform but different temperatures and adiabatic sides has been studied numerically. The numerical results of heat transfer rates are presented for porous Rayleigh numbers (Ra*), based on width of cavity, in the range (Ra*≤500), with layer aspect ratios (Ar), (height / width) ranging between (0.5≤Ar≤5). Plots of streamlines and isotherms to show the behavior of the flow and temperature distribution are presented. The current study shows that the Nusselt number is a strong function of the porous Rayleigh number, and the geometry of the cavity is represented by aspect ratios. Porous Rayleigh number has a large effect on the flow field, whereas any increase in (Ra*) results in changing the flow pattern from unicellular to multicellular flow. Correlation equation has been obtained to show the dependence of Nusselt number on the porous Rayleigh number, and aspect ratio (Ar), as this correlation will be beneficial in design of systems of thermal insulators in the energy storage engineering applications.


Article
Monitoring Process in Turning Operations for Cracked Material Alloy Using Strain and Vibration Sensor with Neural Network Classification

Authors: Nabeel Kadim Abid AL-Sahib
Pages: 1680-1699
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Abstract

Surface finish and monitoring tool wear is essential for optimization of machining parameters and performing automated manufacturing systems. There is a very close relationship between tool wear and machining material parameters as surface roughness, shrinkage, cracks, hard particle ... etc. Monitoring of manufacturing processes plays a very important role to avoid dawn time of the machine, or prevent unwanted conditions such as chatter, excessive tool wear or breakage. Feature extraction and decision making is a matter of considerable interest for condition monitoring of complex phenomena with multiple sensors. In this work, the implementation of a monitoring system utilizing simultaneous vibration and strain measurements on the tool tip is investigated for the shrinkage and crack of cast iron work piece. Machining parameters taken into consideration are cutting speed (116.5 and 136.6) m/min, feed rate (0.17 and 0.23)rev/min respectively and depth of cut (1) mm. Data from the machining processes were recorded with one piezoelectric strain sensor type (PCB 740B02) and an accelerometer type (4370), each coupled to the data acquisition card type (9111 DR). There were 22 features indicative of crack were extracted from the original signal. These include features from the time domain (mean, STD, crest factor, RMS, kurtosis, variance), frequency domains (power spectral density), time-series model coefficient (AR) and four packet features extracted from wavelet packet analysis (RMS, STD, kurtosis, crest factor). The (2x1) self organizing map neural network was employed to identify the crack and shrinkage effect on the tool state. The program used with this process is MATLAB V.6.5. As a result of the present work, we have an SOM model can classifying the crack with minimal error.


Article
Effect of Transverse Base Restraint on the Cracking Behavior of Massive Concrete

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Abstract

The effect of considering the third dimension in mass concrete members on its cracking behavior is investigated in this study. The investigation includes thermal and structural analyses of mass concrete structures. From thermal analysis, the actual temperature distribution throughout the mass concrete body was obtained due to the generation of heat as a result of cement hydration in addition to the ambient circumstances. This was performed via solving the differential equations of heat conduction and convection using the finite element method. The finite element method was also implemented in the structural analysis adopting the concept of initial strain problem. Drying shrinkage volume changes were calculated using the procedure suggested by ACI Committee 209 and inverted to equivalent temperature differences to be added algebraically to the temperature differences obtained from thermal analysis. Willam-Warnke model with five strength parameters is used in modeling of concrete material in which cracking and crushing behavior of concrete can be included. The ANSYS program was employed in a modified manner to perform the above analyses. A thick concrete slab of 1.5m in thickness and 10m in length was analyzed for different widths 2, 4, 8, and 10m to produce different aspect ratios (B/L) of 0.2, 0.4, 0.8, and 1.0 respectively. The results of the analyses show an increase in cracking tendency of mass concrete member as the aspect ratio of the same member is increased due to the effect of transverse base restraint. Accordingly, such effect cannot be ignored in the analysis of base restrained mass concrete structures subjected to temperature and drying shrinkage volume changes.


Article
Competitive Adsorption of Furfural and Phenolic Compounds onto Activated Carbon in Fixed Bed Column

Authors: KAWTHER W. AHMED --- ABBAS H. SULAYMON
Pages: 1721-1736
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Abstract

For a multicomponent competitive adsorption of furfural and phenolic compounds, a mathematical model was built to describe the mass transfer kinetics in a fixed bed column with activated carbon. The effects of competitive adsorption equilibrium constant, axial dispersion, external mass transfer and intraparticle diffusion resistance on the breakthrough curve were studied for weakly adsorbed compound (furfural) and strongly compounds (parachlorophenol and phenol). Experiments were carried out to remove the furfural and phenolic compound from aqueous solution. The equilibrium data and intraparticle diffusion coefficients obtained from separate experiments in a batch absorber, by fitting the experimental data with theoretical model. The results show that the mathematical model includes external mass transfer and pore diffusion using nonlinear isotherms, provides a good description of the adsorption process for furfural and phenolic compounds in fixed bed adsorber.


Article
Numerical Simulation of Heat Transfer Problem in Hot and Cold Rolling Process

Authors: Ihsan Y. Hussain
Pages: 1738-1760
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Abstract

An efficient numerical model had been developed to model the thermal behaviour of the rolling process. An Eulerian formulation was employed to minimize the number of grid points required. The model is capable to calculate the temperature distribution, the heat penetration depth, the convection heat transfer coefficient of cooling, the flow of metal through the roll gap, and the heat generation by plastic deformation and friction. The roll is assumed to rotate at constant speed, and the temperature variations are assumed to be cyclically steady state and localized with a very thin layer near the surface. The Conventional Finite Difference (CFDM) based on cylindrical coordinates was used to model the roll, and a Generalized Finite Difference Method (GFDM) with non-orthogonal mesh was employed in the deformed strip region and the roll-strip interface area. An upwind differencing scheme was selected to overcome the numerical instability resulting from the high velocity ( high Peclet number ) involved in the rolling process. The equations of the strip and roll are then coupled together and solved simultaneously. Both cold and hot rolling heat transfer behaviours, velocity distribution, and heat generation by deformation and friction under typical rolling conditions were presented to demonstrate the feasibility and capability of the developed numerical model. It has been found that, while the strip is under deformation, the bulk temperature inside the strip increases continuously; this is largely controlled by the deformation energy. On the other hand, the strip surface temperature changes much more drastically and it is mainly controlled by the friction heat and the roll temperature. The roll acts like a heat sink, because the coolant heavily cools it. Thus, as soon as the strip hits the roll its surface temperature drops. Since considerable friction and deformation heat are created along the interface and transferred from the neighboring sub-layer, the surface temperature picks up rapidly. Finally, the results of the temperature distribution for both cold and hot rolling and the heat generation by deformation and friction obtained from the present study were compared with previous published work to verify the validity of the numerical solution. Good acceptable agreements were obtained.


Article
Axisymmetric Free Vibration of Thin Prolate Spheroidal Shells

Authors: Mohammed J. Obaid --- Ala M. Hussein --- Ahmed A. Hassan
Pages: 1762-1778
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Abstract

In this paper a detailed study of the theory of free axisymmetric vibration of thin isotropic prolate spheroidal shells is presented. The analysis is performed according to Rayleigh – Ritz method. This method as well as an approximate modeling technique were attempted to estimate the natural frequencies for the shell. This technique is based on considering the prolate spheroidal as a continuous system constructed from two spherical shell elements matched at the continuous boundaries. Through out the obtained results it is found that this method predicted fairly well the natural frequencies of a prolate spheroidal shell for all values of eccentricities.


Article
Sacrificial Anode Cathodic Protection of Low Carbon Steel in Sea Water

Authors: Khalid W. Hameed --- Aprael S. Yaro
Pages: 1780-1790
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Abstract

Cathodic protection is a corrosion-prevention technique which uses the electrochemical properties of metals to insure that the structure to be protected becomes the cathode of an electrolytic cell. Laboratory evaluation was conducted on zinc electrode as anode material that used for sacrificial anode cathodic protection (SACP)of carbon steel. Rate of zinc consumption during cathodic protection of carbon steel pipeline carrying seawater (4 % w/v NaCl solution) were measured by the loss in weight technique. Variables studied were seawater temperature (0-45o C), flow rate (5-900 lit/h), pH (2-12) and duration time (1-4 h). It was found that the rate of zinc consumption increases with increasing seawater temperature, flow rate and duration time and decreases with pH increase. Under the mentioned operating conditions, the rate of zinc consumption during cathodic protection of steel ranged from 5.65×10-3 to 98.9×10-3 g/cm2.day. For the system under investigation, the cell responsible for cathodic protection is Zn/NaCl/Fe.

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Article
Mathematical Simulation of Flow through Hollow Fibre Membrane under Constant Hydraulic Conductivity

Authors: Riyadh Zuhair Al-Zubaidy
Pages: 1792-1802
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Abstract

Distilled water flow through a virgin hollow fibre membrane, HFM is considered as steady nonuniform since the fibre’s wall hydraulic conductivity coefficient is kept constant along the fibre and unchanged during the operation. Under these conditions, two well known laws were used to mathematically simulate the hydraulic flow through the HFM. These two laws are: the Darcy’s Law, to simulate the flow thought the fibre wall, and the Hagen-Poiseuille’s Law, to simulate the laminar flow through the fibre channel. Laboratory measurements were carried out to provide necessary data for the calibration and verification of the mathematical model that was developed based on the Darcy’s and Poiseuille’s laws. A good agreement was obtained between the measured and predicted flowrate values under the same conditions. The developed Mathematical model can be used as a tool to investigate the hydraulic performance of commercial HFM modules. A comparison was made between two commercially available of HFM modules of the same material but differ in the fibre sizes; it was found that there is a difference between its performance and the efficiency of the operation energy.


Article
Influence of Defect in the Concrete Piles Using Non-Destructive Testing

Authors: A'amal A-Saidi --- Yousef Al-Shakarchi --- Mosa Al-Mosawe
Pages: 1804-1816
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This paper presents the results of experimental investigation carried out on concrete model piles to study the behaviour of defective piles. This was achieved by employing non-destructive tests using ultrasonic waves. It was found that the reduction in pile stiffness factor is found to be about (26%) when the defect ratio increased from (5%) to (15%). The modulus of elasticity reduction factor as well as the dynamic modulus of elasticity reduction factor increase with the defect ratio.

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Article
Entropy Method as Criteria for Analysis of a Steam Power Plant

Authors: Moayed Razoki Hasan
Pages: 1818-1833
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In this paper a theoretical analysis of South Baghdad and Dura power plant is carried out according to second law of thermodynamic depending on entropy (irreversibility coefficient or lost work) method instead of exergy (availability) method. In the used entropy method. The power plant is divided into main blocks ( boiler, turbine, condenser, and feed water heater and pumps ). The irreversibility losses and coefficient for each block are calculated and then the overall irreversibility and thermal efficiency of the plant are calculated. The results of this work are compared with previous results, that depending on exergy method. The comparison of results show that both methods give approximately the same results since both of them rely the 2nd law of thermodynamic. Entropy method is simple and intellectually and intuitively satisfying and giving direct relationship between components losses of power plant and its overall efficiency.

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