Print ISSN: 1813-0526

Online ISSN: 2220-1270

Volume 20, Issue 6

Volume 20, Issue 6, Summer and Autumn 2012, Page 1-168


Nonlinear Analysis of Reinforced Concrete Thick Plates Under Effect of RepeatedLoading and Cyclic Heating

Dr. A.H.AHMAD; Jarjery; H. A. AL

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 1-17
DOI: 10.33899/rengj.2012.63332

Abstract
This study includes the effect of cyclic heating and repeated loading on the behavior of reinforced concrete thick plates by using mathematical models to represent the effect of cyclic heating on mechanical properties of concrete and steel, and other models to represent the behavior of both concrete and steel underth effect of cyclic loads.
Plate thickness has been divided into several layers; steel was represented as an equivalent concrete layer. The material properties in each layer of the plate thickness are evaluated according to its temperature. One dimensional heat equation has been used to describe heat distribution through the layers
Reissener’s theory that account for shear strain and transfer of shear forces and assumes that stress distribution across plate thickness is linear has been used to analyze the plates. The finite difference method and dynamic relaxation technique are used to calculate the stress and strain in the plate; also modified increment method is used to represent stress-strain nonlinear relationship.
Reinforced concrete plates have been analyzed in the ordinary temperature and after heating and cooling for three different temperatures (200,400,600)˚C withdifferent Cyclic Loading of (1,2,3,4) cycles .

Keywords: Nonlinear analysis, Reinforced concrete, Thick plates, Repeated load, High Temperature.

Analysis and Simulation of Single Phase Inverter Controlled By Neural Network

Abdul Kareem Z. Mansoor; Ahmed G. Abdullah

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 1-14
DOI: 10.33899/rengj.2012.63362

ABSTRACT
This paper presents the analyses and design of Neural Network (NN) control of a single phase voltage source inverter with an L-C filter using only voltage sensor. A multiple feedback loop PI(Proportional-Integral) controller for PWM (pulse width modulation) inverter is built by root-locus method then simulated using Matlab (Simulink). The proposed NN is traind off-line using the patterns obtained from the simulated inverter with multiple loop PI (Proportional-Integral) controllers. Simulation results show that the proposed NN control can achieve low total harmonic distortion under linear loading condition, small steady state error and good dynamic response under any disturbance change in load. A hardware single phase inverter with programmed pulse width modulation control based on microcontroller is built and implemented with resistive load.

Short term electrical load forecasting using holt-winters method

Dr. Majed Saleh Al-Hafid; Ghazi Hussein Al-maamary

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 15-22
DOI: 10.33899/rengj.2012.63377

Abstract
Load forecasting is a process of predicting the future load demands. It is important for electrical power system planners and demand controllers in ensuring that there would be enough supply of electricity to cope with increasing demands. Thus, accurate load forecasting can lead to an overall reduction of cost, better budget planning, maintenance scheduling and fuel management. Therefore this study aimed to develop new forecasting model for forecasting electricity load demand which will minimize the error of forecasting. This paper presents an attempt to forecast the daily peakdemand of electricity by using an appropriate time series model. It is the Seasonal Holt-Winters method. The performance of this method was evaluated by using theforecasting accuracy criteria namely, the Absolute Percentage Error (APE) and the Mean Absolute Percentage Error (MAPE). Based on these criteria the Holt-Winters method emerged as a suitable model for forecasting electricitydemandin Iraq.

Shear Transfer between Precast Normal Concrete and Self Compacting Concrete through the Interface Surface

JananRasheed Al-Feel; RagadSubhi

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 18-29
DOI: 10.33899/rengj.2012.63358

Abstract
When cast two different types of concrete in the structures or cast new concrete over old concrete it should be act monolithically. As the load applied a shear force between them will cause slip, so treatment or connectors should be used on the interface. The self compacting concrete (SCC) used widely due to its good properties as spreading and passing ability through congested reinforcement. The aim of the present research is to study the shear transfer between precast normal concrete and self compacting concrete by using several methods for surface treatment such as shear-key, sand-blast, chipping or using steel stirrups. And also to study the effect of the compressive strength on the shear force is carried out.The results were shown that the best treatment method of the interface surface to get high shear force and less slip is the sand-blast or using two 6mm reinforcement, and the compressive strength of SCC and normal concrete were enhancethe shear force.

Fabrication and Study of Memory Cell Switching Properties Based on Cu2S Compound

Dr. Khalid Khaleel Mohammad; Faris Hassan Taha

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 23-28
DOI: 10.33899/rengj.2012.63378

Abstract
A variety of materials having large non-volatile resistance change has been studied as potential candidates for next generation of non-volatile memory devices, in this device, information is stored as a change in resistance due to the formation of the metallic filament via the reduction of metal ions in the solid electrolyte. Key attributes are low voltage, low current, rapid write and erase, good retention and endurance, and the ability for the storage cells to be physically scaled to a few tens of nm.This paper presents experimental results for solid state devices based on copper sulfide ( Cu2S ) I-V characteristics.
Keywords: Cu2S memory cell, non-volatile memory

Design and Implementation of Doherty Power Amplifier of Global System Mobile (GSM) of Base station

Dr. Saad A. AL Kazzaz; Kahlan. H. Hamid

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 29-39
DOI: 10.33899/rengj.2012.63385

Abstract
Power amplifier is the main component of wireless communication system. This paper presentsthe efficiency improvement of linear Power amplifier for GSM base station using Doherty Power Amplifier (DPA). ADPA operating at 900 MHz and a supply voltage of (2.5-3)V. The DPA is a combination of a carrier amplifier biased to class AB mode and a peaking amplifier biased to class C mode. Each amplifier was design by GaAs FET using advance design system software package (ADS). The simulation results of DPA are compared with class AB power amplifier that ashow improvement in power added efficiency at output power with acceptable power gain.
Keywords:Doherty Power Amplifier, GaAs FET,Efficiency, GSM,ADS software.

Colors (Their Positions& meanings) in Islamic Architecture

Dr. Ahmad Abdulwahid Thannoon

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 30-49
DOI: 10.33899/rengj.2012.63360

Colors are considered to be one of the complementary design elements in the process of architectural design of any building. Itcontributes in the presentation of the final and overall picture of the work which the designer intends to convey to the recipient.Islamic architecture was characterized by the distinguished use of colors which took part in achieving access to architectural models that have a high expressive abilityin delivering different interpretations to the recipients.
In order to make use of the architectural and aesthetic heritage of colors in Islamic architecture, the details of using colors in Islamic architecture must be clear to be a guide for contemporary architects in the operations of utilizing colors in architecture. After considering a number of previous studies, the research problem can be stated as follows: (the lack of sufficient detailed theoretical knowledge about colors and their achieved meanings in Islamic architecture). Therefore the goal of research is to (identify the colors used in Islamic architecture and their meanings, along with knowing the correlation between the use of specific colors in specific locations within the Islamic building, and the meanings achieved in each use). In order to achieve the goal of research, the researcher employs an approach which includes: (1Building a theoretical framework which includes identifying the most frequently used colors in Islamic architecture, determine their meanings in the Quran and Islamic tradition, and finding out the color assortments used in Islamic architecture. (2Carrying out an analytical study to complete the information on the utilization of colors in Islamic architecture which includes the use of a set of images of Islamic architecture models to represent the samples of the target study. (3Analyzing the results of the analytical study. The research comes out with some conclusions, like the use of colors in two techniques:1) Representation of the natural environment,2) Counteraction with the environment.
Key words: colors, meaning & semantics, Islamic Architecture

Estimate of Penetration Depth of Moist Soils For Mosul City at 6 GHzC-band Microwave Frequency Range

ManafEzzldien Al-Sabbagh

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 40-47
DOI: 10.33899/rengj.2012.63387

Abstract
Results of an experimental and theoretical programs were presented to determine the impact of soil moisture content and the soil composition on microwave radiometric emission and microwave signal skin depth (Penetration depth), as well as attenuation coefficient within soil surfaces. The measurements are depending on the relative dielectric constant that practically carried out by this research. The measurements have been conducted for three common types of soil in Mosul city (ornamental, cropland, and orchard) at 6GHz (C-band) microwave frequency.
The expected brightness temperatures of these soil samples and the skin depth have been computed. The results show that the observed microwave skin depth is relatively high for ornamental type more than that of cropland and orchard.
Keywords: Moist soil, Penetration depth, Brightness temperature, Complex dielectric constant.

Stress AnalysisoftheAbove-Knee ProsthesisduringGait Cycle

BakrNooriKhudher

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 48-59
DOI: 10.33899/rengj.2012.63389

Abstract
In this paper the finite element analysiswas achieved on the above-knee prosthesis to investigate a picture of stress distribution in the socket.Previous works on the prostheses used the symmetry approximationinshape modeling and most of them are all about static loading.The analysisand shape modeling in this work were achieved in high accuracy with theaid of ANSYS 12.1 package software capabilities. Ofthis study, stressanalysis was achieved under dynamic loading at the three main gait cycle;soon after heel strike, foot flat and just before tow off as traditional stagesused in researches. This work lies on the dynamic loading calculated withthe ground reaction forces, dynamic forces, and moments as well as theangular and linear acceleration of foot up to the thigh during the three maingaitcycle.
The stress distribution was achieved and it is imported to note that themaximum stress induced in the socket are at the upper brim whereas mostparts of the socket are consi-dered as a low stress region.

Key Words: stress, dynamic loading, socket , prosthesis, above knee, finite element

Stress Analysis of Centrifugal Fan Impellers

Dr. Muhamed H. Abood; Ayad A. Ghaidan; Mahmood H. Ali

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 60-69
DOI: 10.33899/rengj.2012.63391

Abstract
This paper deals with the determination of stress distribution for a centrifugal fan consists of back sheet, ten airfoil blades and shroud by using Finite element Packaged program (NSTRAN). The results showed that the blade trailing edge and the shroud plate have amaximum VonMises stress which exceeds the yield point of the materials. Thickness effect of each part on the stress distribution in the impeller was determined with fixing the other parts thickness.The result showed that the optimum thickness of the plate is (11mm), for shroud is (9mm) for blade is (3mm), for back sheet plate is (11mm) for shroud stiffener is (3mm). the overall results pointed out that the shroud plate is a critical part and has a large effect on the stress distribution than other parts.
Keywords: Centrifugal Fan, VonMises stress, Finite Element, NASTRAN

Effects of H2SO4 and HCL Concentration on the Corrosion Resistance of Protected Low Carbon Steel

Dr.SamiAbualnounAjeel; Haitham Mohammed Waadulah; DehiaAbdAlkader Sultan

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 70-76
DOI: 10.33899/rengj.2012.63393

Astract
Investigations were carried out to study the corrosion behavior of unprotected and protected low carbon steel using carburizing and hard chrome plating in different concentrations of H2SO4 and HCL solutions. Weight loss method was used for estimation the corrosion rate in the current study.
Theresults show that protected low carbon steels samples by hard chrome platinghad better corrosion resistant (less corrosion rate) than unprotected and carburized low carbon steel samples. Also, the corrosion rate increaseswith increasing acid concentration from (1 to 5)M. for both types of acid used. The corrosion rate of low carbon steel in acid environments indicate that the hydrochloric acidsolution was more corrosive media thanthat of sulphuric acid solutionunderthe same conditions.

Keywords:Corrosion rate;Acid environments;Low Carbon Steel;weight loss method.

Studyof the Effect of Relative Humidity on the Heat Transfer Characteristics for a Fin Exposed to Air at Different Conditions Ziad M. Al-Makhyoul

Ziad M. Al-Makhyoul

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 77-89
DOI: 10.33899/rengj.2012.63395

A study of the effect of relative humidity on the two dimensional heat transfercharacteristics for thetwo types of annular fins of (constant thickness and variable thickness)has been carriedout using finite difference method and grid generation technique of algebraic method to simplify the geometry of fin. The temperature distribution for a fully wet fin and dry fin has been determinedat relative humidity of (0, 50, 75 and 100)%alsofin efficiency, fin effectiveness and heat transferhave been calculated for a range of relative humidity at (10, 20, 30, 40, 50 and 100)% and length of fin from (0.01 to 0.1)m. The effect of the atmospheric pressure was also studied. The study shows that the fin effectiveness and fin efficiency of a fin in the case of fully wet fin are found to be less than those in the dry fin andthe temperature gradient at the tip for a dry fin is greater than that for the wet fin

Key words: Annular fins, relative humidity, heat transfer

Effect of wick structure geometry on the performance of a heat pipe

Dr.HussainH; Raqeeb H. Rajab

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 90-103
DOI: 10.33899/rengj.2012.63397

Abstract
A mathematical model was set up to find the heat transfer coefficient in a heat pipe with a grooved wick structurehaving axial capillaries of different cross sectionsthroughproducinga considerable capillary pressure forced and hydraulic drag. From this viewpointa model is developed and solved analytically to estimate the heat pipe performance. A different geometry groove shapesin the inside surface ofa heat pipe are designed. From the proposed model, numerical optimization is performed to enhance the thermal performance of the heat pipe for measuring the maximum heat transport rate. The exact pressure drop and the temperature drop calculations were performed using finite element modeling by Ansys program.Also, in the present studycomparison between various geometry groove shapeswith same depth (circular, trapezoidal and rectangular) at constant wall heat flux condition is made including the effect of the groove shapes on the heat transfer characteristics in a turbulent tube flow( Reynolds number range 5000–15000).The analytical result for the maximum heat transport rate wasobtained when the geometry is circular whilethe rectangular grooved pipe is decreased by (20) % in comparison with the circular grooved pipes.
Key Words: Heat pipes,wick structure,groove.

Pipeline Architecture for Clipping Straight Line Segments

Dena R. Ibrahim; Fakhrulddin H. Ali

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 104-116
DOI: 10.33899/rengj.2012.63399

Abstract
Sometimes, in computer graphics, there is a need to show a part or a piece of a specific picture to study it accurately. For this purpose a window can be used to select the interested part of the picture for display out of other parts. This window is called a clipping window and this process is called a clipping process .On the other hand, clipping is required when a part of a moving image becomes out of the visible zone for display. So the clipping process is one of the important issues in the field of computer graphic specially for real time applications. Therefore a study of the line clipping with respect to a rectangular window while looking to various methods to achieve clipping process in the image space is presented in this paper. In addition to that, performance measurements are conducted and compared. The paper develops a method to perform clipping in the object space in which the line segment is clipped against a viewing volume. Finally, pipelining is adopted to realize clipping algorithm in hardware.
Key Words : Regional Code, Clipping Window , Viewing Pyramid, Pipeline.

Combined Armature and Field Fuzzy Speed Control of a DC Motor for Efficiency Enhancement

Ahmed M.Adday; Dr.Mazin Z .Othman

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 117-130
DOI: 10.33899/rengj.2012.63401

Abstract

This paper presents the design and implementation of fuzzy logic controller (FLC) to improve the efficiency of a separately excited dc motor .The improvement of motor efficiency is achieved by controlling both armature voltage and field voltage simultaneously which are decided by the FLC. DC-DC converters (chopper Buck) are utilized to control armature voltage and field voltage. Design and MATLAB simulation are presented together with implementation of fuzzy logic controller using microcontroller type(MC9S12DP256B).The results show that the efficiency of the DC motoris clearly increased in light and medium load torques in comparison to the armature fuzzy speed controller.

Key words: speed control of DC motors, fuzzy control, and efficiency enhancement.

Recognition ofBreast CancerUsing Hybrid Method

LoaySalimYahya

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 130-138
DOI: 10.33899/rengj.2012.63405

Abstract
In this paper,a computer aided diagnosis [CAD] system has been developed for tumor detection in digital mammography. The system consists of four parts: firstenhance the image,second Feature extraction using six decomposition levels of two dimensional Discrete wavelet transform (2DWT),the features are extracted from regions of interest(ROI),third Reducing the features extracted using two algorithm energy root mean square and mean algorithm of each set of coefficients in each decomposition level, fourth classification of tumor using three layers artificial neural network (ANN) with (19) features is proposed for classifying the marked regions into benign and malignant.
Experiments are done on 63 benign tumors and 52 malignant one. The recognition rate of the malignant tumor is (96%) while that of the benign ones is (100%). The result shows that the proposed method can classify the breast tumors effectively when using root mean square algorithm.
Keywords: Recognition,Breast Cancer, Artificial Neural Network,root mean square.

Effect of Combined Stabilization by Lime and Cement on Hydraulic Properties of Clayey Soil Selected From Mosul Area

Mohammed MukhlifAljobouri; Dr. SuhailIdreesKhattab

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 139-153
DOI: 10.33899/rengj.2012.63409

Abstract
This paper is aimed to study some of the hydraulic properties (permeability and water retention) of a stabilized clayey soil selected from Mosul area. The optimum lime stabilization percentage was found to be 4 %. Cement amounts of 6 % and 18 % are needed to achieve a minimum unconfined compressive strength of 1400 and 5600 kParespectively “suggested limits for stabilized soil suitable as a base course”. For the same indicated range of strength, a combination of lime-cement ratios of 1-3 % and 2-9 % respectively were found to be sufficient to achieve this limit.Permeability of natural soil was found to increase with treatment of lime, cement and lime-cement. A maximum increasing in permeability about 17 fold was found using 4 % lime. While the permeability was 1.2 folds as a minimum increase when treating the soil with 18 % cement. The soil-water characteristics curve shows that (S-Shape) curves were maintained for natural and stabilized soil.

Experimental and Finite Element Analysis of Steel-Concrete Composite Beams

Dr. Suhaib Yahya Kasim Al-Darzi; Inas Mahmood A.H.Al-Juboory

AL-Rafdain Engineering Journal (AREJ), Volume 20, Issue 6, Pages 154-168
DOI: 10.33899/rengj.2012.63412

Abstract
A new type of perfobond shear connector is suggested, and tested through design and construction of six steel-concrete composite beams separated on three groups formed from standard steel section (W4X13), with total length of 1300mm. The concrete slab connected to steel section by using three types of mechanical shear connectors namely; stud connector and regular circular hole perfobond connectors in addition to newly suggested type of triangular hole perfobond connector. The beams are experimentally tested using two point load beam test to inspect the effects of connector’s type on beam behaviour at yielding and ultimate stages in terms of deflection at mid-span and slip at ends of tested beams. A three dimensional nonlinear finite element model is developed using ANSYS software to simulate beam test up to failure. The results show that, composite beams constructed with newly suggested triangular perfobond connectors developed a strength percentage higher than those with stud connectors, and regular circular perfobond connector. The finite element model validated by comparing with experiments, predicting differences in ultimate resistances of (0.9% to 5.7%) for perfobond connectors and (11.9% to 19.2%) for stud connectors.
Keywords: ANSYS, Connector, Composite, Finite Element, Perfobond, Stud