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Engineering and Technology Journal

مجلة الهندسة والتكنولوجيا

ISSN: 16816900 24120758
Publisher: University of Technology
Faculty: Presidency of the university or centers
Language: Arabic and English

This journal is Open Access

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The Journal aims to disseminate knowledge in the fields of Engineering, Technology and Sciences .All the researches will submit to the scientific evaluation procedures of publishing and documentation. The journal under takes only the publishing of the new researches that had not been published previously on other journals or debated in conferences.

The Instructions of Submitting The Research to Scientific Evaluation:
a- The research should be Submitted in 4 copies in Arabic or English Languages, auther's name should be eliminated from 2 copies only. The abstract should be typed on the front page not exceeding (150 words) in both Arabic and English on size (A4) sheet. Pages should be numbered and not more than (15) page.
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Secondly- The annual subscription in the journal inside Iraq is ID250000) Iraqi dinar, and outside Iraq is (us $250) abroad.
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Engineering and Technology Journal
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ENGINEERING AND TECHNOLOGY JOURNAL
Scientific Refereed Journal Issued by University of Technology, IRAQ
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جمهورية العراق –بغداد
الجامعة التكنولوجية- مجلة الهندسة والتكنولوجيا- ص.ب. 35010
Email: etj@uotechnology.edu.iq
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http://uotechnology.edu.iq/tec_magaz/EN/index.htm
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Republic of Iraq, Baghdad
University of Technology, Engineering & Technology Journal.
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Email: etj@uotechnology.edu.iq

Email: uot_magaz@yahoo.com
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Table of content: 2016 volume:34 issue:8 Part (A) Engineering

Article
Superiority The Use of WiMAX System on Wi-Fi System in The Iraqi Topographic
افضلیة استخدام نظام واي ماكس على نظام واي فاي في الطوبوغرافیة العراقیة

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Abstract

The high prevalence of the Internet services in Iraq have led to the emergence of tight and crowded towers Wi-Fi (Wireless Fidelity) services in residential neighborhoods because of the limited extent of coverage of this system.This led to increased cost of subscriber's services due to the multiplicity of mediators, as this system is limited only to cover the fixed places. In this research,we are compare the effectiveness in terms of coverage area (fixed and mobile ), speed downloading data and other matters.This system is WiMAX: (Worldwide Interoperability for Microwave Access). The WiMAX technology is well suited for cities characterized by the construction of a horizontal and a lack of natural heights or artificial (very high vertical buildings). This fully appliesto the Iraqi topographical, which will lead to lower the overall costs due to the reduction of the towers and equipment to a very small percentage. For example, Baghdad city will need no more than three towers for full coverage , in other hand technical specifications, lower cost to subscribers due to shorter preparation of mediators , reduced substations located in abundance in residential areas. Research will explain by direct comparison between the two systems including the strengths and weaknesses of both, and their behavior according to the topography of Iraqi cities. ان الانتشار الكبير لاستخدام خدمة الانترنيت في العراق ادى الى ظهور مزدحم ومتقارب لأبراج خدمات الواي فاي في الاحياء السكنية بسبب محدودية مدى التغطية لهذا النظام, وهذا يؤدي الى زيادة كلفة الخدمةللمشتركين نظرا لتعدد الوسطاء, كما ان هذا النظام يقتصر فقط على تغطية الاماكن الثابتة . في هذا البحث تتم المفاضلة بنظام اخر اكثر فعالية من حيثالتغطيةالثابتة والمتحركة وسرعة تحميل البيانات وامور تقنية اخرى يتناولها البحث بالتفصيل, وهذا النظام هو الواي ماكس : (Worldwide Interoperability for Microwave Access) ان تقنية الواي ماكس هي ملائمة تماما للمدن التي تمتاز ببناء افقي وعدم وجود مرتفعات طبيعية او اصطناعية ( الابنية العمودية العالية جدا) وهذا ما ينطبق تماما على الطوبوغرافية العراقية, حيث سوف يؤدي الى تقليل الكلف الاجمالية نظرا الى اختزال الابراج والمعدات الى نسبة قليلة جدا فمثلا فأن مدينة بغداد سوف لا تحتاج الى اكثر من ثلاثة ابراج للتغطية الكاملة وبمواصفات تقنية احدث و كفاءة عالية وكلفة اقل للمشتركين نظرا لاختصار اعداد الوسطاء واختزال المحطات الفرعية المتواجدة بكثرة في ازقات المحلات السكنية, كما سوف يوضح البحث النقلات التقنية بأسلوب المقارنة المباشرة بين النظامين ونقاط القوة والضعف لكلاهما وكيفية سلوكهما وفقا لطبوغرافية المدن العراقية.


Article
Fungi Colonies Effect on Fatigue Behavior of 7075Al Alloy

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The effect of fungi colonies on fatigue of 7075 aluminum alloys was studied for specimens corroded at different media. 57 specimensof aluminum alloys were submerged in Shat-Arab water (Sh.A.W) for four months at different conditions (at light media (9 fungi colonies), dark media (80 fungi colonies))and then applying constant fatigue tests after removing the specimens from the corrosion media . The results show that the fungi colonies can corroded Al alloy the reduction of pre-corroded specimens at light media (9 fungi colonies) was 13% and for specimens at dark media (80 fungi colonies) was 22% , and a nonlinear damage model was proposed to predict the cumulative corrosion fatigue life


Article
Synthesis of Mullite Powder from Aluminum Nitrate and Precipitated Silica using Sol-Gel Process

Authors: Hussein Alaa Jaber
Pages: 1491-1498
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In this work, a new route for possibility synthesizing high purity submicron size mullite (3A12O3.2SiO2) powder at relatively low temperature. Mullite precursor has been prepared from mixing precipitated silica powder with solution of aluminum nitrate nonahydrate (Al(NO3)3.9H2O) through sol-gel process, in order to obtain composite powder. The formed precursor gel was calcined at temperatures of (1100, 1150, 1200 and 1250)°C for 1 hour. The influence of calcination temperatures of the mullite synthesis was discussed. The microstructure tests of calcined materials were investigated by x-ray diffractometer (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX). X-ray analysis results identified the mullitization initiated at 1200°C, and the mullite phase was completely formed at 1250°C. The SEM micrographs show the microstructure of mullite powder had been aggregated in the regular and nearly spherical-like appearances with diameters in the range of (100-200) nm.


Article
Finite Element Analysis of Suppression the Vibration of Dish Using Closed Loop Control System

Authors: Nahedh Mahmood Ali
Pages: 1499-1513
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Abstract

A closed loop simulation is used for minimizing of undemanding vibration caused in the dish system. The finite element method is used to model the closed loop control via ANSYS- APDL. In this paper the Bezier function for surface modeling to get the best modeling points for dish is used. A designed surface is represented by sufficient control points, using these control points, the surface has been represented depending on Bezier technique to generate reliable and near-optimal dish surface. The required equations are generated to apply the surfaces and curves efficiently using MATLAP program, then exported to ANSYS to perform closed loop vibration analysis. It can be concluded that the closed loop control system with gain (Kp=4, Ki=1, Kd=0.1) suppression the vibration of the dish with 98% with different thickness and materials of dish. Also the natural frequencies and the mode shapes of the dish is evaluated. Three materials (pure copper, pure aluminum and steel) each with different thickness is taken for the dish (0.8, 0.9, 1, 1.1 and 1.2) mm and for each thickness the responses and the natural frequencies are determined for six modes. The effect of the thickness’s variation on natural frequencies for each material was studied. It can be observed that natural frequency is direct proportional with the thickness of the dish.


Article
Modeling of a Greater-Zab River Watershed Using Arc SWAT for Stream Flow and Hydrologic Budget

Authors: Thair S. K
Pages: 1514-1529
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Abstract

Soil Water Assessment Tool (ArcSWAT2009) model is applied on the Greater-Zab River catchment at north of Iraq. The model was calibrated from 1993-2002 and validated from 2003-2013.The calibrated model for hydrological conditions was used to assess the water quantity (monthly stream flows).The study identified optimum parameters and with widest ranges of variation for better rates simulation. The water balance components were correctly estimated. The results showed that the average simulated stream flow for the study period (1993-2013) was 363 m3/sec which is less than the average value of stream flow (417 m3/sec) for the period (1930-1992) .The water shortage problem effects on the management of water resources. Based on statistical indicators, the evaluation indicates that the model had a good performance for both calibration and validation periods in Greater-Zab River watershed. The model can be used efficiently in semi-arid regions to support water management policies in Iraq. The model performance evaluation showed a good correlation between the observed and simulated monthly average stream flow for calibration and validation periods with R2 (0.99,0.87),EN.S(0.99,0.86) and D ( 2.76,1.22) respectively. A sensitivity analysis was carried out on the major input parameters and the results showed that there are ( 11 ) out of (41) parameters sensitive. The most sensitive is the (CN2). Results of hydrologic budget show that the ratios of the annual base flow and the flow of the hydrograph shape to the total flow are 20 % (base flow index) and 42 % respectively. The lateral flow, computed as a percentage of average annual rainfall varies greatly from 4.8% to 38% and the actual evapotranspiration is much lower than potential evapotranspiration. The ratio between the average yearly precipitation and potential evapotranspiration was 45 %. In a future study, it is recommended to use land cover and climate change scenarios, their projected impacts and adaptation. The study results are helpful for the management and planner of water resources in Iraq which relate to the sustainability and water quantity.


Article
Optimal Robust Controller Design for Heartbeat System

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In the present work, an optimal control approach is suggested to design a robust controller for the heart system. The work objective is to generate artificial or synthetic optimal Electrocardiogram (ECG) signals using the nonlinear optimal robust control. This includes the design of a state feedback controller to stabilize the ECG under uncertainty. The approach key is to reflect the uncertainty bound in the cost function, and the solution to the optimal control problem is a solution to the robust control problem. The robust optimal control strategy is applied for nonlinear heart system; different structures of uncertainties have been sought. Unfortunately, for the present case study only unmatched structure of uncertainty has been found in both state and input matrices.


Article
Predicting the Delivery Time of Public School Building Projects Using Nonlinear Regression

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The delay in delivering public school building projects in Iraq is one of the major problems that face the construction of new school buildings. In order to enable the concerned governmental agencies to predict the expected delivery time of these projects at the time of contract assignment, two forecasting modelsare developed to aid in this matter. After reviewing a wide range of literature to determine the most common causes of delay, a questionnaire is distributed to owners, consultants, supervising engineers and contractors engaged in public school building projects. The results of the questionnaire were analyzed using the relative importance index. Nine most important causes of delay in public school building projects were assured by the respondents namely; the contractor's financial status, delayed interim payments, change orders, contractor rank(classification), work stoppages, contract value, experience of the supervising engineers, contract duration and delay penalty. Historical data concerning these causes was extracted from past records of the General Directorate of School Buildings, thennonlinear regressionwasemployedto develop two models (A & B)that can predict the final delivery time of public school building projectshaving (12) and (18) classes separately, where the Levenberg-Marquardt technique was used to develop the mathematical equations.The developedprediction equations show a degree of average accuracy of (97.79%) for schoolshaving (12) classes and (97.11%) for schools having (18) classes,with (R2) for both NLR models of (81.25%) and (87.58%) respectively.


Article
Influence of Uniaxial Loading on the Strength of Slender Columns

Authors: Alyaa Hussein Mohammed AL-Najafi
Pages: 1549-1563
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Abstract

A column is said to be slender if its cross-sectional dimensions are small compared with its length, and its strength is reduced by second-order deformations. Several methods are available for slender column design including codes and researchers. A number (135) of slender column tests is used in this work; from the literature are reanalysis by different methods. Using these tests’ results new proposal formulae are made for slender column design. When compared to existing methods the proposed one gives better correlation with test results. The proposed methods were derived using regression analyses for the based on different parameters. Theoretical analyses of columns are sampled to study the major variables affecting the column for each method of analysis. The paper is mainly concerned with making suggest and comparison between several methods analyzing slender columns.

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Article
Fuzzy-TOPSIS Model for Optimization Hot Corrosion Resistance of Inconel718 Coated by Yttrium-doped Aluminizing-Siliconizing Process

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The objective of this study is to find out the optimum hot corrosion resistance and hardness for Inconel718 coated by simultaneous yttrium-doped aluminizing-siliconizingprocess. The hot corrosion parameters selected for the experiments are Na2SO4, NaCl, and V2O5. The optimization is carried out by choosing three input parameters at two levels. Multi objective optimization technique, TOPSIS optimization approach is used for maximizing the hot corrosion resistance (minimizing hot corrosion rate Kp),and hardness. ANOVA is performed to investigate the more influencing parameters on the multiple performance characteristics. It also helps to calculate percentage contribution of each parameter. Finally, accuracy of optimization was confirmed by conducting confirmations. Results indicate feasibility of TOPSIS analysis in continuous improvement in hot corrosion resistance.


Article
On-Line Tuning Sliding Mode Controller Design for Nonlinear Inverted Pendulum System based on Bees Algorithm

Authors: Khulood E. Dagher --- Ahmed Ibraheem Abdulkareem
Pages: 1575-1587
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This paper proposes a modified swing control for a nonlinear inverted pendulum system by utilizing the sliding mode controller based on the on-line tuningBeesalgorithm as speed of optimization and accuracy of results. The goal of the proposed nonlinear controller is to obtainthe optimal force control action for the pendulumcart in order to stabilize the pendulum in the inverted position precisely and quickly.The optimal parameters of the nonlinear controller are on-line tuned by Bees algorithm and guided by Lyapunov stability criterionto reduce the amplitude of the sliding mode signum function in order to eliminate the chattering phenomena and make the smoothness control action.Matlab simulation results confirm the validity of the proposed controller algorithm in terms offast dynamic response, minimizing the pendulum’s angle tracking error to the zero radianat 2.5 second and obtaining the optimal and smooth force control action without saturation state, with the minimum number of fitness evaluation of the algorithm.


Article
Experimental Study of Heat Transfer Parameters of Impingement Heating System Represented by Conductive Target Plate of Resistive film

Authors: Assim H. Yousif --- Amer M. Al Dabagh --- Salah H. Abid Aun
Pages: 1588-1604
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The current experimental study focuses on the heat transfer characteristics and pressure losses for impingement systemwhich is used in cooling the liner of gas turbine combustor. Recent experiment method of conductive heat transfer technique with resistive film in the back side target plate is introduced. The present experimental model measured both the heat transfer coefficient for inner target surface and the wall cooling effectiveness for outer target surface. To physically explain the phenomena associated with interaction flow area, a computational fluid dynamic code (Fluent 14) is employed. The continuity, momentum and energy equations arecomputationally solved to analyze the flow field in the jet impingement area. The tests models of the impingement plate are made from round jet holes of inline and staggered arrays arrangement with jet to jet spacing of four-hole diameter. Jet Reynolds numbers of 4200 to 15000 and jet height to diameter ratio of 1.5, 2.0, and 3.0 are maintained. The inline array, as expected enhanced the wall cooling effectiveness over that of the staggered array by10.3%andboth jet spacing and Reynolds number have an evident effect on the discharge coefficient. Empirical correlations are obtained for both arrays arrangement to predict the area-averaged Nusselt number as a function of jet governing parameters.


Article
Topographic Survey with Analytical Close Range Photogrammetry

Authors: Abbas Zedan Khalaf --- Sally Salwan
Pages: 1605-1614
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Topographic survey uses to determine the relative locations of points (coordinates) on the earth's surface by measuring horizontal distances, differences in elevations and directions. Generally speaking the production of large scale topographic maps requires precise topographic survey with land surveying instrument such as (Total Station) which is costly and time consumed. The objective of this research is to produce topographic maps using an unconventional means through application analytical close range photogrammetry. The analytical close range photogrammetric method is characterized by low efforts and cost, the speed of topographic survey works, as well as the possibility of measuring and / or assessing places inaccessible. Photos strip was selected at University of Technology as a case study with area (400 m2). The fieldwork started with generation of ground control points around the area. A theodolite (wild T2) was used to measure the ground (X, Y, and Z) coordinates for GCPs within the study area. The strip consists of eight overlapped images, overlap more than 60% were captured using a single non metric digital camera (Canon EOS D500) (with a resolution of 15.10 mega pixels). After capturing images for study area two steps were used for processing data.The first step was used to process these images for producing 3D coordinates from 2D images with different methods by using two software. The first software using Matlab2014b dealing with different methods Sequential (R-I) and bundle adjustment (BA) methods, and another software ERDAS IMAGINE (LPS) using block bundle adjustment. The second step was used GIS software to producing large scale topographical map.The computed Root Mean Square Error (RMSE) for three methods (Resection – Intersection, Bundle Adjustment and Bundle Adjustment Block) and it was found that the RMSE in R-I method is (2.917cm) , RMSE in B-A method is (2.882cm) and RMSE in Bundle Block Adjustment method is (3.112cm). The final result was a topographic map with scale (1:100 and 1:200).


Article
Bearing Capacity of Closed and Open Ended Pipe Piles in Clayey Soil

Authors: Ban S. Hussein --- Falah H. Rahil --- Mohammed A. Mahmoud
Pages: 1615-1623
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This paper investigates the impact of close and open ended condition on the capacity of pipe piles installed in medium clayey soil using pressed or jacked and hammered techniques and tested under the effect of vertical static compression load. 36 experimental model steel pipe piles (18 models for each open and closed ended) introduced and analyzed to clarify the influence of soil plug formation on the behavior of pipe piles.Different parameters are studied such as pile diameters (2.5, 3.5 and 4.1) cm, piles lengths (30, 40 and 50) cm and type of installation methods (pressed and hammered(. Results of the test program indicated that the ultimate load capacity of open-ended pipe piles tended to increase as the pile diameter and length increase for both pressed and hammered. The plugging of open piles does not contribute significantly on the capacity of pile in clay. For all model pile tests the load capacity of the closed ended piles is (5 – 30) % greater than that of the open ended for both type of installation (pressed and hammered) under the same geometric conditions.


Article
Heat and Chemical Treatments for Sawdust/UPE Composites

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Sawdust filler taken from White Cham (a type of wood) were mixed with unsaturated polyester (UPE) at 20, 30 and 40% volume fractions. the mechanical and physical properties of the composites treated by NaOH alkali at 0.5, 1, 1.5 and 2% (W/V) along the effect of volume fractions were investigated .The results showed improving in properties comparing with untreated sawdust filler, while heat/alkali treatment at 2%NaOH at different temperature 40, 60, 80 and 100 ˚C also showed improving in properties .the optimal mechanical properties had been obtained at 1% NaOH, and detracted at 2% NaOH. Yet, the mechanical properties at 2% NaOH were improved when heat treated. The optimal mechanical properties were obtained at 80 ˚C. It is worth mentioning that the optimization process was based on the tensile test. Also the thermal conductivity results show better insulation after the treatments especially at 100 oC.


Article
Electroflotocoagulation of Emulsified Cooling Oils as a Method of Pollution Control

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This research includes the removal of pollution produced from used coolant emulsion oils especially soluble oil (7201). In many types of liquid effluents, oil – water emulsions can be among the most vexing to treat, even through such streams may contain only very small quantity of oil. Untraditional oil removal operation (electroflotocoagulation) is used in this research, which consist of glass cell 102 cm in height. A sacrificial Aluminum Anode is placed on a perforated glass disc at a distance 24-cm from the bottom. Above it is placed the upper electrode, Aluminum cathode is fixed on a movable glass tube. Product water was fed into settling vessels from the outlet arm 17 cm above the glass disc. Oily flocs and aluminum hydroxide were removed by a second side arm 45.5 cm above the product water arm. Sets of experiments were carried out to find the efficiency of electroflotocoagulation to remove the concentrate soluble oil (7201) from water. Multivariables were studied such as: applied potential, space between the two electrodes, settling time and initial soluble oil (7201) concentration. These variables have effect on the soluble oil (7201) percentage removal. The experimental results were represented in two mathematical em-pirical correlations and three dimensional graphs which describe the soluble oil (7201) removal efficiency as a function of current, settling time and in the second, initial soluble oil (7201) concentration respectively.


Article
PSO-Based EKF Estimator Design for PMBLDC Motor

Authors: Ahmed Hammood Abed --- Mohammed Moanes E. Ali
Pages: 1651-1665
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The estimation of motor state variables is an important criterion in the drive performance, especially for high accuracy required, for that reason it’s-necessary to estimate rotor-position-continuously not for sixty-electrical-degrees as in most existing methods. In this work the speed and position for the rotor of Permanent Magnet Brushless DC Motor (PMBLDCM) was estimated by using extended Kalman filter (EKF), this work is divided into two parts, the first one deals with design and simulation of PMBLDCM with EKF as an estimator, the results are introduced by manually selected EKF parameters (Q & R) matrices, The second one deals with investigation the performance of the use of PSO technique to optimize the performance and operation of EKF, the main use of PSO here is to optimize value for EKF parameters (Q and R), the results proved that by tuning the EKF parameters by PSO the estimated values for speed and position is very-close-to the actual value-(estimation-accuracy is increased). The resultant error clearly decreases when tuned by EKF parameters for example at full load case the speed RMS error is 0.24 for 10μs sampling time, although the RMS error is 9 for 10μs sampling time trial and error selected EKF parameters.


Article
Prediction of Contact Angle for Sintered Alloy for Solid Freeform Fabrication

Authors: Falih Hamza Edan
Pages: 1666-1672
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The present study aimed to predict theoretically the contact angle between liquid copper dropson well-polished carbons steel. The theoretically established model was relied on standard tables for wetting parameters available in the literatures from which mathematical relations were extracted from the mutual relations existed among the parameters in the equations. The established model using Math Lab program was then used to obtain standard contact angle values for theoretical proposed standard contact geometry with impressive chemical indicators affected by the polishing processes. The contact system was the Fe-C / Cu couple which was usually fabricated by P/M route for high load self-lubricated bearings with carbon content in the range of 3-4 wt%. Resulted values for the predicted contact angle indicated a decrease of the contact angle as the temperature increased approaching zero at a high temperature of 1084 oC approximately. This will directly reflected on the degree of wetting of molten copper with iron, with an associated increase in rate of copper diffusion at the carbon steel surface, which was considered as indicatorsfor surface chemistry interfere with the polishing process.

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Article
Shear Lag in Reinforced Concrete T-Beams with Web Openings

Authors: Eyad Kadhum Sayhood --- Nisreen Saleh --- Ahmed S.Hanon
Pages: 1673-1687
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In this paper, an extensive study is carried out 18 beams on the behavior of T-beams (8 with web openings, 10 without openings). Compressive strains distribution at the flanged are investigated with the presence of the openings in web to recheck the effective width of flange with real flange width. Parametric study are considered in this paper includes the compressive strength, longitudinal flexuralreinforcement,flangereinforcement,shear reinforcement and theweb openings (location, shape, size). Generally, standard codes of practice have overestimated effective flange width due to concentrated load effect, and codes do not take into account the web openings effect. Based on the results, the enhancement in effective width for each parameter were 9.1%-13.36%(compressive strength),10.1%-13.3%(longitudinal flexural reinforcement),7.6%-18.2%(flange reinforcement),3.35%-5.7%(shear reinforcement), the web openings reduced the effective flange width by 15% (openings at mid span ) and 5% ( openings at quarter span ) and the circular opening gavean optimum effective width better than rectangular opening were located both at quarter span.


Article
Effect of Using Plastic and Rubber Wastes as Fine Aggregate on Some Properties of Cement Mortar

Authors: Basil S. Al-Shathr --- Iqbal N. Gorgis --- Rafid F. Motlog
Pages: 1688-1699
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Abstract

This research describes the production of lightweight cement mortar using four types of fine aggregates including chopped rubber tires, chopped plastic wastes, a mixture from the previous types by 1:1, and a mixture composed from substitution of 10% from the previous type by natural sand. Theuseofthese wastes has rolein getting rid oftheir hugequantitieswhich constitute a fundamentalenvironmental problembecause of the difficulty of itsdegradation. Four, cement to aggregate ratios have been used. They are1:0.5, 1:0.7, 1:1, and 1:1.2 for each aggregate type mentioned above, with changing w/c ratio and superplasticizer content to have a constant flow of about 23%. Also, the effect of curing samples by different methods, including continuous submerge in water, autoclave curing for 3 hours, and carbonation curing by 50% and 100% CO2 at 75oC for 90 minutes, was studied. The results indicated that it is possible to produce lightweight cement mortar, using any type of aggregates mentioned above, with compressive strength satisfying the requirements of clay brick class C of Iraqi Standard, that used in partitions, for a mix proportion of 1:1, except when using chopped rubber tires that need using mix proportion of 1:0.5 to satisfy the strength requirements, where the use of this aggregate type needs higher w/c ratio and superplasticizer content to get the required flow, which leads to lower strength in comparison with the other types. As for chopped plastic aggregate, although it needs lower water and superplasticizer content to get the required flow and strength, care should be taken to balance betweenthe amount of waterand superplasticizer addedto avoidthe possibility of segregation in it. So it was found that using the mixture of chopped plastic and rubber aggregate give the best properties. Results also indicated that using all aggregate typeswith cement: aggregate mix proportion 1:1 satisfy the flexural strength requirements of American Standards for cellulosic fiber insulating boards, and were with thermal conductivity valueslower than that for brick and concrete having density lower than 2000 kg/m3. The results indicated that partial replacement of 10% mixed waste aggregates by normal sand cause increase in strength but in the same time increase density and thermal conductivity for the produced mortar. Results also indicated that curing by autoclave or curing with 50% or 100% CO2 cause increase in the 7 days strength compared with those cured by water but they show almost the same strength at 28 days age.


Article
Human Thermal Comfort Evaluation in Open Spaces of Two Multi-Story Residential Complexes Having Different Design Settings, Duhok-Iraq

Authors: Turki Hasan Ali
Pages: 1700-1715
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Abstract

To achieve a sustainable residential area, open spaces must promote comfort and invite people to stay outdoors and prolonging their stays, which will contribute to a more lively residential areas offering greater interaction between its inhabitants. Thermal comfort is an essential factor that should be considered in any urban design process, urban design characteristics of any project have a strong influence on human thermal comfort at outdoor spaces, like its spatial organization and landscape elements, the paper aims to assess the impact of spatial organization differentiation on thermal comfort of inhabitants in two different residential multi-story complexes in Duhok city. Thermal comfort for an urban context in hot and semi-dry climate zone based on the physiologically equivalent temperature (PET) index have been adopted and simulated by ENVI-met program, two simulations were conducted for each complex through climatic data of the hottest day in summer and coldest day in winter of 2013. The results reveal that the two complexes have not provided a comfortable space during the two seasons in general, but it showed that the second complex has a better performance in this respect for the two seasons, in spite of the poor landscaping it has, the paper concludes the importance of the urban design characteristics represented by the spatial organization on thermal comfort of the inhabitants at open spaces at such kind of projects and climate, and the necessity of adopting more compact and close spaces.

Table of content: volume:34 issue:8 Part (A) Engineering