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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Jadriyah, Baghdad
Iraq
Mobile:
Email: joengbag@uobaghdad.edu.iq

Table of content: 2006 volume:12 issue:1

Article
Combined Convection Heat Transfer to Thermally Developing Flow in Horizontal Circular Cylinder

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Abstract

Experiments were conducted to study the local and average heat transfer by mixed convection for hydrodynamically fully developed but thermally developing laminar air flow in horizontal circular cylinder . The experimental setup using an aluminum cylinder as test section with 30 mm inside diameter and 900 mm heated length (L/D=30) is subjected to a constant wall heat flux boundary condition. The investigation covers Reynolds number range from (400 to 1600) , heat flux varied from(60W/m2 to 400w/m2) and by using an aluminum entrance section pipes (calming sections) having the same inside diameter as test section pipe but with variable lengths as entrance sections. The entrance sections included a long calming section of length 240 cm (L/D=80) and two short calming sections with lengths 60 cm (L/D=20), 120 cm (L/D=40). The results present the temperature variation along the cylinder surface and the the local and average Nusselt number variation with the dimensionless axial distance (Z+) . For all entrance sections , the results show an increase in the Nusselt number value as the heat flux increases. Also, the mixed convection regime can be bounded by a suitable selection of (Re) number ranges and the heat flux ranges. The obtained Richardson number (Ri) range varied approximately from(0.1171 to 12.54).


Article
Free Vibration of Beam Elastically Restrained Against Translation and Rotation at Ends

Authors: Nabil H. H
Pages: 17-24
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Abstract

An approximate solution of the vibration of elastically restrained , uniformed and non-uniformed beams with translational and rotational springs is obtained using Rayleigh-Ritz approach. The frequencies are presented for wide range of restrained parameters and some of these have been compared with those available in the published literature illustrating the accuracy and versatility of the approach. It is believed that the results present in this paper will be of use in design of beams , shaft, and piping under dynamics consideration.


Article
Two-Dimensional Numerical Model for Thermal Pollution of Singel Source in River

Authors: mohsin Jasim Nasir --- Rafa H. Al-Suhaili
Pages: 25-35
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Abstract

The aim of this research was to apply a numerical model capable of describing the thermal pollution in rivers. For this purpose a two dimensional numerical model was applied for estimating temperature distribution in a river. Momentum Conservation Equation and Thermal Energy Equation were used to describe the distribution and diffusion of temperature along the river subjected to thermal pollution point source. Furthermore, the model incorporates the ( k-e) turbulence model to calculate the distribution of turbulent viscosity. The pressure distribution was determined using hydrostatic pressure equation. The partial differential equations were formalized and simplified to be solved using Alternative direction implicit-explicit method ( ADI) with upwinding technique. The resulting system of linear simultaneous equations were then solved using Gauss-Elimination method. A laboratory physical model was built to find experimental data. These data were used for model verification with data obtained from Al-Daura power station and Tigris river. The model was found to be in sensitive to the wind speed. The comparison of observed results from Al-Daura power station and laboratory physical model with those computed by the numerical model show a good agreement. The maximum absolute difference percentage are ( 16.2%, 8.6%) respectively.

Keywords


Article
Mixed Convection from Electronic Equipment Component at Different Position at Enclosure by Primitive Variables Method

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Abstract

A numerical study of mixed convection cooling of heat dissipating electronic component, located in a rectangular enclosure, and cooled by an external through flow of air is carried out. A conjugate problem is solved by primitive variables method, describing the flow and thermal fields in air. The interaction between the components is of interest here, depending on their relative placement in the enclosure, and different configuration are considered. For Re=100 laminar, steady flow is predicted for up to Gr/Re2 =25 according to head source location in the enclosure. The mixed convection regime, where the buoyancy effects are comparable to the forced flow, occurs at values of Gr/Re2 between 0.01 and 25 . the results are of values in search for suitable placement of electronic components in an enclosed region for an effective heat removal. In general, it appears that the location of the source on the left vertical wall is the most favorable in terms of cooling. Laminar results are predicted up for up to Gr= 2.5 *105 for all configurations studied.


Article
Determination of Depth of Placement of Tunnels and Cavities by the Boundary Element Method

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Abstract

A boundary element numerical algorithm has been developed for the determination of stresses and deformations around cavities and tunnels. A study of the influence of depth below the ground surface on the distribution of stresses and deformations around cavities and tunnels is presented in this paper. The soil is assumed to behave linearly elastic. A computer program has been built to perform the numerical computations. The results show that with increasing the depth of placement of tunnel or opening below the ground surface, the settlements decrease. The maximum stresses occur at the haunches of the tunnel rather than at the crown. For the circular cavity that is considered in this paper, it was found that with increasing the depth below the ground surface (depth/tunnel diameter > 3), the surface settlements do not exceed 6 % from those obtained for the case of no-cavity condition.


Article
Study of the Effect of Vehicle Driver Behaviour on Vehicle Emissions of Carbon Monoxide at Signalized Intersections

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Abstract

Considerable concentrations of vehicular emissions at signalized intersections and streets, in urban area are health- related issues of concern to society in general. This paper presents an examination for the effect of vehicle driver behavior on vehicular excess CO emissions. The examination process based on site observations. Four Signalized intersections in Erbil City which, satisfy the objectives and specifications of this study selected, and the necessary traffic behaviour and vehicle exhaust emission data collected. The required traffic data abstracted from video play back using EVENT computer program, which provide coded digital representation for the requisite traffic activities. The abstracted data stored on floppy disks in the form of digital computer files. These files processed using computer programs developed for this purpose to abstract the necessary information from the raw data. Among the obtained traffic information are vehicle data classified according to the type of fuel used into two classes. The first class is gasoline powered vehicles which consisted of taxis and private cars covering different model year, engine condition and size, type of fuel injection system, number of cylinders. These data observed under different ambient air temperatures. The second class is the diesel-powered vehicles, which consists mainly of truck type vehicles. Following the processing stage, the obtained data presented and analyzed statistically to evaluate the relationship between driver behaviour, which showed reasonably good relationship with the excess CO emissions. The results of this study are useful for the local authorities, traffic engineers and transportation planners. This is because, the obtained results assist in the adoption of suitable method of intersection control for the purpose of reduction of CO emissions and hence, reduce level of this type of air pollution.


Article
Application of Decision Support System in Construction Projects use in Cost Management

Authors: Ahmed M. R. Mahjob --- Sidqi I. Razzouqi
Pages: 85-97
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Abstract

This work is concerned with introducing new methods and techniques for the projects management In construction industry. This research suggest that the Iraqi engineering staff, who work in construction sector, have a poor knowledge about the subject of Decision Support System (D.S.S.) in spite of that this subject have a wide uses in construction companies in the world. So the researcher presents this study to introduce and to increase the knowledge about the concept of decision Support System. This research consist of the questionnaire process for construction companies, then the research use The questionnaire results in building a proposed Decision Support System, also the questionnaire Process indicate the relation between the decision structure and the organizational levels. The results obtained from the questionnaire process shows that there is a requirement for Decision support System in cost control decisions support. So the researcher build a Decision Support system for cost control process which can be used by the planner and estimator for different types of projects. The researcher also applies and evaluates the proposed system in some Iraqi construction companies. The application and evaluation process recommended the needs for applying the Decision Support System for project management in construction companies.


Article
Removal of Scale Deposited on the Internal Surfaces of Pipes in Cooling Systems

Authors: Ajwa saber majeed --- Abbas H. Sulaymon
Pages: 99-112
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Abstract

The possibility of using inhibited hydrochloric acid in descaling of water deposits on heat exchanger and cooling system tubes have been investigated. A dynamic flow system was designed for this state. Experiments were carried out using different, temperatures. Solution flow rates, times, and different hydrochloric acid concentrations inhibited with hexamine. kinetics of acid - iron oxide scale reaction was studied using hydrochloric acid .The kinetics analysis showed that the acid- FeO scale reaction followes 1st order reaction. It was found that the FeO scale removal was mass transfer controlling process. Iron-oxide scale removal process was analyzed as mass transfer operation and adequate semi-empirical correlations for scale removal ( or mass transfer rate) under different conditions, in a dimensionless form have been obtained. The results of iron- oxide scale removal (or mass transfer rate) are compared with many proposed models particularly those based on the concept of analogy among momentum and mass transfer. Prandtl- Taylor analogy showed a good agreement with experimental mass transfer results.


Article
Application of Vibration Measurement to Detect Damage in Casting

Authors: Ehab N. Abbas --- Adnan N. Jameel Al-Tamimi
Pages: 113-126
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Abstract

Modal testing has become commonplace in many industries today as a research and development tool. In this capacity, it is used primarily during product prototype development and for vibration problem in general . Many types of structural or parts faults will cause changes in the measured dynamic response of a structure. These changes will, in turn , cause change in the structure’s modal parameter . The purpose of the present work is to propose an improved damage detection and location based on the measurement of modal parameter (natural frequency and mode shape ) before and after faults , which they have varying extents, for three different sizes of Aluminum casing plates. This local damage can be translated into or characterization as a reduction of the local stiffness which , simulated in the presented numerical models using software package. After measured natural frequency , if a change is detected a statistical method is used to make the best match between the measured changes in frequencies and the family of the theoretical predictions. This predicts the most likely defect location . Analytical results are also used to check numerical results , which showed a good agreement with it , standard Aluminum plates were also investigated in this work . It results were compared with casting results for two boundary conditions . Also , the defect location charts that plotted with the support of deriving stiffness sensitivity equation showed a good agreement between the predicted defect site and the actual defect location for most of the study cases .


Article
Implementation of FPGA-Based RISC for LNS Arithmetic by Software & Hardware

Authors: N. H Abbas
Pages: 127-139
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Abstract

Field Programmable Gate Arrays (FPGAs) have some difficulty with implementation of floating – point operations. In particular, devoting the large number of slices needed by floating- point multipliers prohibit incorporating floating point into smaller, less expensive FPGAs. An alternative is the Logarithmic Number System (LNS) , where multiplication and division are easy and fast. LNS also have the advantage of lower power consumption than fixed point. The problem with LNS has been the implementation of addition . There are many price /performance tradeoffsin the LNS design space between pure software and specialized-high-speed hardware .This paper focuses on a compromise between these extremes. And on a small RISC core design ( loosely inspired by the popular ARM processor ) in which only 4 percent additional investment in FPGA resources beyond that required for the integer RISC core more than doubles the speed of LNS addition compared to a pure software approach . This approach shares resources in the data path of the non –LNS parts of the RISC so that the only significant cost is the decoding and control for the LNS instructions under consideration , are more cost effective than pure software and be as cost effective as more expensive LNS- FPGA implementations that attempt to maximize speed .


Article
Anodizing of Aluminum-Magnesium Alloy using Chromic Acid Process

Authors: Khalid A. Al-Zameli --- Adil A. Al-Hemiri
Pages: 141-149
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Abstract

Aluminum-magnesium alloy has been anodized using chromic acid as an electrolyte. The effect of voltage in the range of 15-60V, electrolyte concentration in the range of 20-110 g/l, electrolyte temperature in the range of 30-60 Co and time of exposure in the range 25-8S minutes on the coating weight of the anodic film are studied. The experimental data was fitted in terms of the coating weight and the coefficients of third order polynomial are estimated. Optimum conditions of the studied variables are predicted and found equal to 32V. 85 g/l,50 Co and 70 minutes.


Article
Probabilistic Approach to Machine-Components Grouping in Celluar Manufacturing Systems

Authors: Zuhair I.A. Al-Daoud
Pages: 151-161
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Abstract

In this paper existing group technology techniques are reviewed and an alternative method using probabilistic approach to machine-components grouping in cellular manufacturing systems is introduced where it is based on production flow analysis, which uses routing information. A common feature of this approach is that it sequentially rearranges row and columns of the machine part incidence matrix according to predefined index and block diagonal is generated. The steps of this method are to assign the 1's in each row and column a probability weight, which alternately rearranged in descending order until a block diagonal matrix is created. It does not need to decide in advance the number of required cells. It also overcomes the limitation of computational complexity, inherited in exiting group technology methods, especially for large scale and complex problems.


Article
An Investigation into Thermal Performance of a Tapered Glass Window

Authors: Luma F. Ali
Pages: 163-179
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Abstract

The conjugate heat transfer problem through a glass window with non-uniform thickness is presented. The problem was studied using the fully implicit finite difference numerical technique. The tapered glass window is subjected to a convective boundary condition on the outer uniform side of the window and the heat transfer comfortable temperature . The upper and lower edge of the tapered section is also at constant temperature but equal to the main temperature between the indoor and outdoor temperature . In the first part a rectangular cross section an area of 4mm width and 1 m height was taken under study . While, in the second part of the study , a tapered cross section with difference tapered angles of 0.05, 0.1,0.15 and 0.2 degree was held. Another case of the equal cross section area of the tapered and the rectangular cross section was also studied. Good results were obtained and reported graphically . It was found that the ratio of that loss by convection from the linear tapered to the rectangular section increases with the increasing of time and the tapered angle.


Article
Experimental Investigation of Laminar Mixed Convection in an Inclined Annulus

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Abstract

Experiments were carried out to study the local and average heat transfer by mixed conversation to a simultaneously developing air flow in horizontal, inclined, and vertical concentric cylindrical annulus. The experimental setup consists of an annulus has a radius ratio of 0.555 and inner cylinder with a heated length 1.2m subjected to the constant heat flux while the outer cylinder is subjected to the ambient temperature. The investigation covers Reynolds number range from 154 to 845 , heat flux varied from 96 W/m^2 to 845 W/m^2 , and annulus angles of inclinations α=0◦ (horizontal ) , 40◦ , 70◦ , and 90◦ ( vertical) . Results demonstrate the temperature variation along the inner cylinder surface and the local Nusselt number Nuz variation with the dimensionless axial distance , for all angles of inclinations which shows an increase in the Nuz values as the heat flux increases and as the angle of the inclination moves from the vertical to the horizontal position .


Article
Effect of Harmonics on a Solid-Rotor Induction Motor

Authors: Ahmed Th. Radhi --- Ali M. Saleh
Pages: 199-217
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Abstract

The paper records a study of an investigating the performance of a solid-rotor induction motor with a rectilinear inverter excitation to identify the effects of the associated time harmonics. The performance is determined experimentally by using a stator of a three-phase laboratory induction motor that is fitted with a solid-steel rotor and compared with the theoretical model developed which uses the Fourier components of the supply voltage waveform. Final conclusions are drawn from comparing motor performances with sinusoidal and inverter excitations. An equivalent circuit model is developed to determine the harmonic currents. The development of the theoretical model make use of the results of existing field analyses. Harmonic currents and other performance details including the possible interactions between the co-existing harmonics are determined and discussed. The measured values of torque, input current and power over full speed range with the two types of excitation are presented, and compared with the theoretical values. The waveforms of current, phase and line voltages are analyzed experimentally and compared with simulation results. The theoretical results correlate well with measured results and the significant harmonic effects are identified.

Keywords

Harmonics --- induction motor


Article
Production of Graphite Electrodes Binder from Iraqi Asphalt

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Abstract

Basrah crude oil Vacuum residue 773+ K with specific gravity 1.107 and 4.87wt. % sulfur, was treated with hexane commercial fraction provided from Al-Taji Gas Company for preparing deasphaltened oil(DAO)suitable for hydrotreating process. Deasphaltening was carried out with 1h mixing time, 10ml:1g solvent to oil ratio and at room temperature. Hexane deasphaltened oil was hydrotreated on presulfied commercial Co-Mo/γ-Al2O3 catalyst in a trickle bed reactor. The hydrotreating process was carried out at temperature 660 K,LHSV 1.3 h^ –1, H2/oil ratio 300 l/l and constant pressure of 4MPa. The hydrotreated product was distillated under vacuum distillation unit. It is found that the mixture of 75% of vacuum residue with 25% anthracene satisfies with requirements for graphite electrodes binder.


Article
A Wavelet Neural Network Ramwork for Speaker Idntifcation

Authors: Saleem M-R. Taha --- Dhiadeen M. Salih --- W.A. Mahmoud
Pages: 227-236
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Abstract

This paper introduces a new model-free identification methodology to detect and identify speakers and recognize them. The basic module of the methodology is a novel multi-dimensional wavelet neural network . The WNN approach include: a universal approximator ; the time – frequency localization : property of wavelets leads to reduced networks at a given level of performance ; The construct used as the feature mode classifier . Wavelet transform has been successfully applied to the processing of non – stationary speech signal and the feature vector that obtained becomes the input to the wavelet neural network which is trained off-line to map features to used for the classification procedure. An example is employed to illustrate the robustness and effectiveness of proposed scheme.

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