Print ISSN: 1681-6900

Online ISSN: 2412-0758

Volume 32, Issue 7

Volume 32, Issue 7, August 2014, Page 196-1886

HVDC Transmission Systems based Multi-level Voltage Source Converters for Iraqi Super Grid

Adil Hameed Ahmed; Ahmed Saeed Abdul-Sada

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1602-1617

High Voltage Direct Current Transmission (HVDC) with Voltage Source Converter (VSC) technology provides substantial technical and economical advantages for different applications compared to conventional HVDC transmission systems based on thyristor technology. This paper is focusing on the modeling and analysis of Three-Level Neutral Point Clamped (NPC-VSC) as it is one type of multi-level voltage source converter Diode-Clamped Circuit (DCC).This system is regard as light system based on HVDC transmission, of high power ratings (up to 600 MW). Application of the proposed technique is adopted and tested for Iraqi Super High Voltage Grid (400 kV), where the proposed model is simulated using MATLAB. The results show a good response of the control system for certain fault conditions considered to show the advantage of using such system.

Studying the Rheological and Diffusion Properties of Polypropylene-Polymethylmethacrylate Reinforced with Bentonite

Abbas A. Jawad

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1618-1639

In the present research , the rheological and the diffusion properties of polymer melt composed of (polypropylene- polymethylmethacrylate ) unfilled_ filled with different amounts of Iraqi bentonite powder (4,8,12 and 16) wt% were studied. Single screw extruder was used for development of these blends .The rheological behaviour of these blends was investigated by using rotational concentric type rheometer .
The rheological properties shear rate( ( , apparent viscosity (a) and shear stress (τ) , at various temperatures ( 240 ˚C, 250˚C and 270 ˚C) were studied and found to be increase with increasing the amount of filler and decrease with increasing temperature. The flow curves were determined in the range of shear rate from about (2.625*10 2 to 4.70*10 2 ) s-1. The activation energy was also calculated, the values of activation energy varied from (102.2148 to 131.2206) KJ/Mole for different formation.
Absorption test was carried out in Glycerin at different immersion time. The diffusion coefficient (D) values ranged (1.54*10-8 to 2.48*10-3) cm2/sec for immersed in Glycerin.
The diffusion test also was carried out at different temperatures in order to show the effect of temperature on diffusion coefficient. It was found that the diffusion coefficient values increase with increasing temperature. All these samples are obeyed Fickian behavior and the activation energy (E) increases with increasing amounts of Iraqi bentonite powder (4,8,12 and 16) wt%.

Experimental Analysis of Heat Transfer with Dropwise and Filmwise Condensation on Inclined Double Tubes Heat Exchanger

Abdulhassan A. Karamallah; Assim H. Yousif; Ban M. Mohammed

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1640-1654

Dropwise condensation provides larger heat transfer coefficients compared to filmwise condensation, as discovered in the year 1930 by Schmid et al. Dropwise condensation can be described as a phenomenon of the incomplete wettability of a surface.
The wettability of the surface is responsible for the formation of the respective type of condensation and has a very strong effect on the performance of the heat transfer process. Likewise, the wettability of the surface has a very strong effect on the subcooling of the condensate, for constant cooling performance.
Although the conditions necessary for promoting dropwise condensation are well known since several decades, and experiments with coatings as promoters have been carried out successfully, at least in part, the application of dropwise condensation is still today in a testing phase.
The main problems in the realization of dropwise condensation are the insufficiency of the theoretical description of working boundary surface phenomena, such as complete or incomplete wettability and their strong dependence on influences caused in the practical operation by contamination, oxidation of the surface, adsorption layers, and gas enclosures.

Design and Implementation of Programmable Multi-Mode Digital Modulator for SDR Using FPGA

Majid S. Naghmash

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1655-1670

The design of programmable multi-mode digital modulator for software defined radio (SDR) technology using FPGA is developed and investigated in this paper. The system generator from Xilinx and MATLAB tools are used for FPGA design as well as the implementation of the modulator over a Virtex-4 FPGA board. The HDL language on Xilinx ISE is used to generate the bit stream of the modulator algorithms into ADC/DAC device and FPGA board. The modulated signal obtained from MATLAB simulation is evaluated with the tested signal to verify the system functionality. Lastly, the optimally synthesized netlist of the integrated design is downloaded into Xilinx Virtex-4 FPGA MB development board. The verification of DAC output signal via oscilloscope demonstrate the empirical real-time signals similar to the simulated waveforms. Results shows the successfully implementation steps as timing constraint of FPGA is accepted without error. The proposed design is promising to enhance the current and next generation of communication systems with less power consumption compared with conventional design in term of FPGA Slices and Look Up Tables (LUTs) during the implementation process. The improvement in Slices and LUTs produce by ISE project utilization summary is 65% and 79% respectively.

The Effect of Carbon Fiber Reinforced Polymer Length on the Strengthened of Concentrically loaded Reinforced Concrete Beams : Finite Element Analysis

Nada S. Assi

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1671-1683

Carbon fiber reinforced polymer (CFRP) plates are commonly used to increase the ultimate strength of concrete structures in flexure. CFRP plates are also an effective means of rehabilitation and strengthening of concrete structures. In this paper an analysis model is presented for reinforced concrete beams externally reinforced with CFRP plates using finite elements method adopted by ANSYS. The finite element models using a smeared cracking approach for concrete and elastic shell elements for the CFRP plates. The results obtained from the ANSYS finite element analysis are compared with the experimental data for four beams with different conditions from research , three of which were externally strengthened with different amounts of CFRP reinforcement by changing the length of CFRP plate. The comparisons are made for load-deflection curves at mid-span over a span of 2000 mm, failure load and the optimum length of CFRP plate that can be used for flexural strengthening and achieve the adequate load – carrying capacity. The results obtained from the ANSYS finite element analysis were calculated at the same location for the experimental test of the beams. The accuracy of the finite element models is assessed by comparison with the experimental results, which are to be in good agreement. The load-deflection curves from the finite element analysis agree well with the experimental results in the linear range, but the finite elements results are slightly stiffer than that from the experimental results. The maximum difference in ultimate loads for all cases is 11%. The optimum length of CFRP plate equal to 83% of the full span length, obtained from the finite element analysis shows good agreement with that from the experimental test. Four additional models are used to find that 80% of the full span length is quite enough to be optimum length and beyond which the increase in the ultimate capacity is small and can be neglected to reduce the cost of the material.

Improvement of DOA Estimation based on Lanczos Algorithm

Sinan Majid Abdul Satar; Hussein Abdul Adil Mohmmad

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1684-1694

In this paper, the problem of estimating the Direction Of Arrival (DOA) is presented. DOA based on Eigen Vector Decomposition (EVD) shows that the computational complexities are costly and high so that eigen structure algorithms suffer for limited application in real time signal processing environment, to reduce the computational complexities, a new approach base Lanczos algorithm is proposed instead of using Eigen Vector Decomposition.
Since the Minimum-Norm Method (MNM) based on EVD is considered as one of the best techniques for DOA, Therefore, one of the efforts in this paper is directed to investigate the performance of Minimum-Norm Method (MNM) and compare it with Proposed Method (PM), so different computer simulation programs were used to do this job. The simulation results done by assist of (Matlab ver.7), shows that the proposed method can outperform better results to make the proposed method better suitable for radar, sonar, and passive detection application.

A 2.4 GHz Differential Class-E power Amplifier with on-chip Transformers for Bluetooth systems

Abbas H. Issa; Ahmed S. Ezzulddin; Sarab M. Ghayyib

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1695-1706

This work presents the design and simulation of a differential class-E Power Amplifier (PA) for class-1 Bluetooth systems in 0.13 μm RF CMOS technology. The proposed PA can deliver 21.57 dBm output power to a 50 Ω load at 2.4 GHz with 65.59 % Power-Added-Efficiency (PAE) from 1 V supply voltage. In order to achieve fully integrated PA, on-chip balun transformers are designed and improved for converting single-ended input signal to differential signal in the input side and differential signal to single-ended output signal in the output side. The results are obtained using microwave office 2009 (version 9.00).

Separation of Aluminum Chloride from White Kaolinite by Slime Leaching Process

Sami Abualnoun Ajeel; Faeza Ali Sameer; Nawal Izat AbdulLatif

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1707-1719

White kaolinite materials are available raw materials in the western desert in Iraq which exist in Al-Amige region within sediments near the surface. White kaolinite is a high grade raw material which is rich in alumina and its reserve is about 20 million Ton .and because of its locality and its ability of economical investment so the idea of separation of the alumina from it is appeared. The white kaolinite is calcinated at 6000Cfor one hour .The slime leaching for it was applied using hydrochloric acid at different variable conditions (time, molarity ,and particle sizes ) to produce aluminum chloride .The product material can be used as paint manufacturing , antiperspirants ,petroleum refining , product of synthetic rubber and making detergents. The best results were obtained at particle size of-106+75micron, 3 molarity ,3 hour and at 800C, 80 r.p.m. and solid: liquid (1:3). The alumina grade in the powder after separation was reduced from 28% to 5.069 %, and the absorption degree of the Aluminum Chloride was 2.91 and the separation percentage was 82.34 %.

Study of Wear Behavior of Aluminum Alloy Matrix Nanocomposites Fabricated by Powder Technology

Muna Khethier Abbass; Mohammed Jabber Fouad

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1720-1732

In the present work, the dry sliding wear behavior of Al-12wt%Si matrix nanocomposites reinforced with single addition of 4wt.% Al2O3 or 4wt.%TiO2 nanoparticles, and with hybrid addition of 4wt% (Al2O3 +TiO2) nano particles is investigated. All nanocomposites samples were fabricated by powder technology by mechanical milling of the base alloy (Al-12wt%Si) powder and nanopowders of Al2O3 and TiO2, followed by cold pressing at 100bar and sintering at 520 oC for 90min. Vickers hardness test was done by using Vickers hardness tester. Archimedes technique was used to measure the density of sintered samples and porosity calculated as physical tests of sintered samples. Also AFM, SEM were used to investigate the morphology of mixed powders and nanocomposites samples.
Pin – on Disc wear tests were carried out at room temperature under dry sliding conditions with using different normal loads and sliding times. Worn surface micrographs were investigated based on the optical and scanning electron microscopy observations of wear tracks and wear debris morphology. It has been found that nanocomposite with 4wt% Al2O3 nanoparticles shows the highest hardness than other nanocomposites. It was observed that the wear rate or weight loss of the base alloy and nanocomposite samples increases with the increase in applied load and sliding time. But the nanocomposites samples showed lower wear rate than the base alloy within the same conditions.

Effect of Cavity in Sandy Soil on Load Distribution of Pile Group

Mohammed Y. Fattah; Karim H. Ibrahim. Al-Helo; Hala H. Abed

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1733-1751

The present study investigates the influence of presence of cavities on adjacent buildings especially in the case of piled structures. The presence of cavity affects on the bearing capacity and settlement of piled foundation.
This paper presents an experimental study to investigate the behavior of model piles embedded in sandy soil of dry unit weight 16.8 kN/m3. Model piles were tested in a sand box with load applied by a hydraulic compression jack and measured by means of a load cell. The settlement of the piles was measured by means of two dial gages; three strain gages were attached on piles to measure the strains and to calculate the load carried by each pile in the group by the strain indicator. Two types of piles (single pile and group of piles (1x2)) were tested in the laboratory as a free standing pile group.
A prototype of a cavity was used and placed adjacent to the piles at different distances from the pile centerline and different depths from the surface. The effect of variation of cavity locations (X), cavity depths (Y), and cavity diameter (d) on the load and settlement of the pile and groups of piles have been studied for all tests.
It was found that the presence of the cavity in the soil reduces the ultimate failure load of the pile. For single pile, the reduction rate is about (10% to 60%). For pile group (1x2), the reduction rate is about (40% to 80%). As intuitively expected, induced pile axial force is largest for the case where the level of the cavity is located below pile tip because the cavity is located within the zone of large displacement

Design of Wind Turbine Energy System Based on Matlab/Simulink

Zaki Majeed Abdullah; Ahmed M. T. Ibraheem Alnaib; Omar Talal Mahmood

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1752-1763

This paper presents modelling and simulation of wind turbine - electrical generation system using Matlab/Simulink software package. This system consists of wind turbine coupled with the Permanent Magnet Synchronous Generator (PMSG). The PMSG is connecting to the load through a three-phase full wave rectifier and a buck converter. Control strategy based on Fuzzy Logic Controller (FLC) is presented to regulate the outputvoltage of the wind generation system irrespective of variations in the wind speed and load. The wind turbine and FLC are implemented in Matlab/Simulink based on its mathematical model of its equivalent equations. Simulation results show that the controllers can regulate the output voltage of the system under varying wind speed and load conditions.
Keywords: Wind Turbine, PMSG, Rectifier, Chopper, and FLC.

Effect of Blank Holder Inclination Angle on Deep Drawing of Round Mild Steel Cup with Flange

Karem M. Younis; Jalil J. Shukur

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1764-1775

The work aim to study the effect of the blank holder slope angle on deep drawing parameters such as: punch force, strain state and thickness distribution along cup wall of drawn part. 3-D model of cylindrical cup of (40mm) outer diameter, and (0.5mm) thickness from mild steel (1008–AISI), has been developed. Due to the symmetry in the specimen geometry, only one fourth portion of the model needed to be analyzed. A commercially available finite element program code (ANSYS14.0), was used to perform the numerical simulation of the deep drawing operation. The numerical results of this model were compared with experimental results. Four types of blank holder and dies with slope angle (0o, 7.5 o, 15 o, 22.5 o) .the experimental and numerical results show that the required punch force decrease with increase in blank holder slope angle , The best thickness distribution over all zones in produced cup obtained when using blank holder with angle α= 15º.

Systematic Analysis and Design of Single-Phase Boost PFC Converter for Induction Motor Drive

Jafar H. Alwash; Turki K. Hassan; Raed F. Abbas

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1776-1796

This paper presents a systematic analysis and design of a single-phase boost power factor correction (PFC) converter supplying an inverter-motor drive system. The PFC converter is a single-stage single-switch boost converter that uses a current shaping technique to reshape the non-sinusoidal input current drawn by the motor-drive system to a near sinusoidal waveform. The resultant is a current input with almost free-harmonics, which comply with the IEC 61000-3-2 limits, and a system operates with near unity power factor. The other function of the boost converter is to provide a regulated DC voltage to the inverter-motor system. The motor drive system incorporates a1-hp induction motor fed by a Pulse Width Modulation (PWM) inverter with open-loop voltage to frequency (v/f) control. This drive system is analyzed as a load across the converter and its equivalent resistance is extracted and used in the PFC controller design. The theoretical and experimental results are compared to validate the analysis.

Design and Implementation of Discrete Multitone Modulator for Digital Subscriber Line Using FPGA

Hadi T. Ziboon; Ikhlas M. Farhan

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1797-1810

This paper presents a design, simulation and implementation of the Discrete Multitone (DMT) modulator for digital subscriber line (DSL) for both complex and real transmission based on Software Defined Radio (SDR) using FPGA. DMT divides the available bandwidth into parallel sub-channels. There are two techniques to transmit data by DMT. Complex transmission and real transmission .Real transmission is preferred for DSL, since it needs single wire but uses twice number of IFFT. The Simulink HDL Coder has been used for converting the MATLAB-Simulink and M-files models to VHDL language. The verification of the generated VHDL code has been done using Altera- ModelSim, while the synthesis reports and board programming files have been obtained using the Quartus II. The FPGA is used as a platform for SDR. The implementation by using Simulink HDL coder shows the feasibility and flexibility in solving the problems of implementation of the main units of DMT for both complex and real transmission. The main units of DMT are serial to parallel converter,MQAM,IFFT,Parallel to serial and cyclic prefix. The experimental results show that there is coincidence between generated real and complex signal and simulated real and complex signal by generated MATLAB (Simulink and M-file) and Simulink HDL Coder.

Studying and Modeling the Effects of Quartz Addition and Heat Treatment on Mechanical Properties of Glass-Ceramic Coating

Ali H. Ataiwi; Ibtihal A. Mahmood; Jabbar H. mohmmed

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1811-1824

In this work, a new glass-ceramic coating has been developed and applied, as a single coat without prior chemical treatment of the surface, using the dipping technique on metal substrate. the coating are designed for application on varies grades of low alloy steel, the selected substrate was low carbon low alloyed steel with (0.2)%C. Various heat treatments at temperatures ( 500,550, and 600˚C ) at different times (60 & 120)min and with quartz addition in the range (0-15)% were used to obtain a glass-ceramics that have the optimum coating properties. These coating have been characterized by x-ray diffraction analyses and the results showed presence of a number of microcrystalline phases which are formed during the heat treatments. The results showed the suitability of this coating for protection the metal substrate which was used in present work. The results of tests also indicated that the mechanical properties ( hardness, adhesion strength, and thermal stability) of resultant coating were greatly improved by both addition of quartz into enamel frit and heat treatments for all cases, this is attributed to the formation of complex network from crystalline phases(Li2SiO3, Li2TiSiO5, NaAlSi2O6, and SiO2) which are the main phases in the resultant glass-ceramic coating. It has been found that the heat treatment at 600˚C for 120min with 15% quartz addition brought the optimum values for ( hardness, adhesion strength, and thermal stability) of resultant coating which are improved by (70.58%, 33.84%, and 39.68%) respectively. Mathematical modeling is implemented and regression equations are obtained using ( SPSS ) software to predict the experimental data for mechanical properties of resultant coating. Comparing the predicted and measured values gives high prediction accuracy. The accuracy of prediction has been (98%, 98.5%, and 97.4%) for ( hardness, adhesion strength, and thermal stability) respectively.

Removal of SO2 over Modified ActivatedCarbon in Fixed Bed Reactor: II.Effect ofProcess Variables on the Characteristics of Mass Transfer Zone

Neran Khalel Ibrahim; Shahrazad Refat Raouf; Zainab Adnan Nasir

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1825-1842

Adsorption of sulfur dioxide (SO2) onto NiO supported activated carbon (Ni/AC)in fixed bed reactor under different operating conditions was studied. Using 7Ni/AC catalyst, the effect of two process variables: namely gas flow rate(80 ≤ Q ≤ 290l/h equivalent to superficial gas velocity 263 ≤ Vg ≤ 955 cm/min) and bed height(4 ≤ H ≤ 8)cm on the desulfurization activity and the characteristics of mass transfer zone(MTZ) were investigated. Breakthrough curves for SO2 under various adsorption conditions were obtained and some characteristic parameters such as breakthrough time (τ0.05), exhaustion time(τ0.95)and length of mass transfer zone (LMTZ) were derived from these breakthrough curves. The experimental results revealed that on increasing gas rate for all bed heights two regions are developed.
Keywords: SO2 Removal, Ni Supported Activated Carbon, Fixed Bed Reactor, Breakthrough curves, Mass Transfer Zone

Design and Modelling of (Fe /Zro2) Functionally Graded Materials (Part I)

Alaa Abdulhasan Atiyah; Ahmed Taifor Aziz

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1843-1858

It is hoped to design and modeling of five layers Fe/ZrO2 functionally graded materials for high temperature applications in this paper. The design part, were started with the supposing of connecting two distinct material layers. The two layers were associated by a graded interface composing of three layers. Thickness of graded layer (i.e. RF) was designed and tested with the FEM method through the COMSOL package. The software was used extensively to examine the best graded part thickness percentage (i.e.RF %) that connecting the two different material layers. Two parameters were examined such as N and RF% to determine the best value of (N) and (RF %) that imparts low residual stresses. Thermal stresses that developed as a result of exposing of material to high temperature environments also calculated. The simulation indicates that the sample with (RF= 80% and N = 0. 7) Provides minimum residual stress at high working temperature 1000℃ with good mechanical properties.

Surface Modification of Multiwall Carbon Nanotubes for Metal Matrix Nan composite Applications

Ahmed Ali Moosa; Abdul Qader Faisal; Righdan Mohsen Namus

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1859-1869

MWCNTs first functionalized by using two steps covalent functionalization process. Functionalized MWCNTs coated with copper by using electroless coating process. Three different groups of Cu/MWCNTs nanocomposites with (0.1, 0.5, 1, 2, 3 wt% MWCNTs) were prepared by means of powder technology. The first group contains multiwalled carbon nanotubes as received (Cu/MWCNTs), second group contains functionalized multiwalled carbon nanotubes (Cu/FMWCNTs) while the third group contains coated multiwalled carbon nanotubes (Cu/CMWCNTs). Comparison between these samples show that the coating of MWCNTs was remarkably improve hardness and wear resistance of copper nanocomposite. The improvement in mechanical properties is due to the enhancement in both adhesion with matrix and dispersion ability of MWCNTs. SEM, XRD, FTIR were used to characterize of coating process and Cu/MWCNTs nanocomposites.

Comparative Study of the Mechanical Properties of Two Groups Ternary Polymer Blends Composites

Sihama E. salih; Akram R. Jabur; Teeb A. Mohammed

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 1870-1886

Thermoplastic polymer blends composites were prepared as strips by double screw extruder. The prepared composites consists of two groups, the first group was prepared as ternary polymer blend according to the formula [84%LLDPE:15%((100-X)%PP:X%PVP):1%B.P] with X values (0,4,8,12,16%).The second group was prepared with replacing the weight ratios for each of the LLDPE and PP according to formula [84%PP:15%((100-X)%LLDPE:X%PVP):1%B.P] with same X values. Mechanical properties for all prepared samples (tensile, flexural, compression, impact toughness, hardness and creep tests) were studied. The results of this research showed that the fracture strength, young modulus, compressive strength, flexural modulus and creep modulus for the two groups increase with increasing in PVP percentage and the highest values were at 8%PVP, while elongation decreases with addition PVP to the composites. Moreover flexural strength, shear stress and hardness values increase slightly with increasing in PVP percentage for both groups. In addition to that, the impact strength and fracture toughness for the second group samples were high and reach the maximum values (0.45 kJ/m²) at 4%PVP and (4.58 Pa√m) at 8%PVP respectively, as well as all results show that the second groups samples have better mechanical properties.

Investigation of the Elements of Critical Thinking in the Educational Process in the Jurisdiction of Architecture

Nawfal Josef Rizco

Engineering and Technology Journal, 2014, Volume 32, Issue 7, Pages 196-221

Thinking is a mental act the person uses it when he is facing a special attitude or a problem. as he tries to reach the appropriate solutions. Which is an integral part of the behavioral pattern of human which determines the compatibility with the external environment, the critical thinking aims to form the mind so as to judged ideas and perceptions and other provisions to know its mental compatibility and consistency before adopting them. So the critical mentality do not accept the matters and accidents as it is, and do not rush to believe them ,but expose them to the mental balance and to the test of experiment to verify their validity or mistake and in order to activate the above on the academic level ,so the research has sought to investigate the elements of critical thinking in the educational process in the jurisdiction of the Architecture and on two levels, first : the efficiency of the performance of curriculum vocabulary and the second : the efficient functioning of the teaching staff, and for all academic stages. To achieve this objective the research has hired the conceptual theoretical frameworks which passing by the critical thinking aspect and its components and standards because of its importance in the academic educational process and test its consistency with the criteria which straighten university quality performance on the same two levels in order to reach to the extent of the activation of critical thinking elements at the respondents. It was between the results of the research that has been detected some clear deficiencies in the activation of the elements of critical thinking on the two researched levels , according to the questionnaire that was included in the case study process , according to ranges indexed in the research results .