Print ISSN: 1813-0526

Online ISSN: 2220-1270

Volume 23, Issue 1

Volume 23, Issue 1, Winter and Spring 2015, Page 1-169

Effect of Intermittent Feeding on the Performance of Plug Flow Activated Sludge System under Different Hydraulic Retention Times

Kossay K. Al-Ahmady; Enas Ahmad Kader AL-Taee

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 1-11
DOI: 10.33899/rengj.2015.101021

In this research, the effect of intermittent feeding on the efficiency of plug flow activated sludge reactors has been studied. An experimental plant has been constructed and operated. The plant consists of five identical reactors with the volume of (15) liter working in parallel under the same operating conditions for each of discharge; sludge recycling ratio; hydraulic detention time and the organic load. Four of these reactors had been worked at the intermittent (ON/OFF) feeding mode with the ratios of (1/1), (2/2), (4/4) and (6/6) for the first, second, third, and fourth reactor respectively, while the fifth reactor worked at continuous feeding mode. The results showed that, removal efficiencies for each of ammonia (NH3) and phosphorus (PO4) were close in both of intermittent and continuous feeding system, while the concentrations of (COD) in effluent were less in the intermittent reactors. Removal efficiencies of (COD), (NH3), and (PO4) decreased with reducing the hydraulic retention, whereas nitrate removal efficiency increased with decreasing of hydraulic retention time.

Effect of Organic, Nitrogenous and Phosphorus Loads Variation onthe Removal Efficiency of Organic and Nutrients Pollutants In Duckweed Based Wastewater Stabilization Ponds

Kossay K. Al-Ahmady; Zena A. AL-Shrefy

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 12-22
DOI: 10.33899/rengj.2015.101022

In this research, an experimental laboratory plant was constructed in order to evaluate the effect of organic, nitrogenous and phosphorus loads on the removal efficiency and behavior of duckweed based wastewater stabilization ponds. The results of the study showed that; covering the oxidation ponds with duckweed improve their ability to treat higher organic and nitrogenous loads. In addition, covering the oxidation ponds with duckweed improve their ability to treat higher organic and nitrogenous loads. Organic and nitrogen load can be increased from (65 kg/ ha. day) to (158 kg/ ha. day) and from (49 kg. ha. day) to (111 kg/ ha. day) by covering the ponds by duckweed. On the other hand, the results of research also showedthat; increasing nitrogen and phosphor load leads to decrease removal efficiency of nitrate, nitrite, and increases removal efficiency of ammonia and phosphate at the same hydraulic retention time.

An Efficient Algorithm for Eye Detection in Faces Images

Luqman Sufer Ali; Hussein Mohammed Hussein

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 23-29
DOI: 10.33899/rengj.2015.101023

Human Eye’s detection is one of the significant difficulties in computer vision. Eye detection utilized in medical applications and computer control system for people with special needs. In this paper, an efficient algorithm for eye detection is proposed. The algorithm utilized both luminesce and chrominance components to detect face region and later with geometricalcharacteristics to fine detection for pupil center. The experimentsresults show that the algorithm is works with 93% of images database used for testing with small computation time means the algorithm is usable in real time applications.

‏Ultrasonic Attenuation of (Al-SiC) Particulate Aluminum Matrix Composite

Awad Hallosh Khidhir; Qussay Younis Hamid

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 30-39
DOI: 10.33899/rengj.2015.101024

The present research deals with preparing (11) samples of composite materials with metal matrix represented by Aluminum alloy (AA3003)cast and particulate reinforced by (SiC) having particlesvolume fractions (5,10,15 Vol.%).The alloy matrix and composite materials were prepared by stir casting method. Stir casting technique wasused to increase the homogeneity distribution of the particles in alloy matrix. Average particlesizesof (75,106,150μm) were used. The aim of this study is to investigate the relationships between ultrasonic attenuation and stirrer speed ,reinforcement contents of SiC reinforced Al-alloy (AA3003)composites .Attenuation (longitudinal and shear)were measuredusing the pulse-echo amplitude technique with normal and angle probes of (45°,60°,and70°) and frequencies of (2 and 4MHz) .The results show an increase in volume fraction of particles causes an increase in attenuation. It was also found, that the ultrasonic attenuation decreases with increasing particle size. It was observed that an increases in stirrer speed, increases in the longitudinal ultrasonic attenuation.

Effect of Friction Stir Welding Parameters on the Joint Efficiency of the Weldments forHigh Strength Aluminum Alloys(2024-T351,7075-T651)

Waleed Jalal Ali; Qays Hazim Ismael

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 40-50
DOI: 10.33899/rengj.2015.101025

The aim of the present research was to study the effect of friction stir welding parameters such as ( tool rotation and tool transverse speeds) on the joint efficiency of
(6.1 mm) thick weldments of aluminum alloys (7075-T651,2024-T351) , which are used in aircraft industries andare poorly weldable by fusion welding such as (TIG,MIG and Laser) welding .Friction stir welding welds were carried out on a traditional milling machine .Tow tool rotation speeds (900 and 1120 rpm) and three travelspeeds (28,40 and 56 mm/min) were selected for the friction stir welding of each alloy. Thestrength of the weldments has been investigated using the tensile test with standard specimens at room temperature.It was observed that the strength and joint efficiency of the weldments decreased with increasing the tool rotation speed and decreasing travel speed with improvement in ductility.The best weldments joint efficiency of the (2024-T351) alloy is (86.41%) and for (7075-T651) is (73.5%) these were obtained at tool rotation speed (900 rpm) and travel speed (56 mm/min).

Effect of Main Channel Roughness on The Branching Flow

Nashwan K. Alomari; Khalid Y. Taha; Moayed S. Khaleel

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 51-61
DOI: 10.33899/rengj.2015.101027

The work concerns a laboratory study to investigate the effect of changing the bed roughness of the main channel on the branching discharge and separation zone formed in the main channel as a result of discharging flow through a branch channel.The ratio ofmain channel roughness to the roughness of the branch channel bed has been changed between (1.7 – 3.9) for two branching angles (30˚ , 90˚ ) and for different values of main channel discharge ranged between (7 – 17) L/sec. Laboratory result shows that branching discharge ratio increases by the increasing the total discharge through the main channel at roughness ratio less than (2), where's the branching discharge decreases at roughness ratio greater than (2), and stay constant at roughness ratio about (2) for all discharge passing through the main channel.The result shows that the length of the separation zone decrease with the increasing in the roughness ratio and total discharge through the main channel.

Laboratory Study For Estimating The Removing Sediment From Upstream Weirs Using Bottom Outlets

Moayad S. Khaleel; Akram Kh. Mohammed

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 62-72
DOI: 10.33899/rengj.2015.101028

In this research, a series of laboratory experiments were carried out to estimate
the removing sediment amount from upstream weirs using bottom outlets. The
experiments were conducted in a laboratory channel (24.6 m) in length and (0.81 m)
wide, in middle of which a weir was fixed. Six discharges were allowed to flow with,
three different sediment concentration for each. The results showed that there is a direct
relation between the area of the holes, Froude number and the amount of sediment
removed, the depth of aggradation near weir location decreases with increasing the
number of holes. A dimensionless equation was created to compute the amount of
sediment removed in terms of area of the holes with a coefficient of determination
(0.895) and the percentage of the highest and lowest difference between the measured
and calculated sediment amount were (15.7, 0.2), respectively.

Effect of Airports Elevation on the Jet Engine Thrust (Off – Design Operation)

Khalid Ibrahim Hasan

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 73-84
DOI: 10.33899/rengj.2015.101030

It is well known that airport elevation with respect to sea level has a considerable effect on the jet engine thrust. In this study an airplane type (Viperjet, Learjet) with jet engine type (J85-CJ610 ) was selected and tested at different elevations to show the effect of elevation on the engine thrust . The study includes theoretical background about turbojet engines, thrust, atmosphere and the change of some parameters and the relation between the thrust and altitude. According to the values of engine thrust in this study at different airports in the world for the selected engine mathematical calculationshows that the thrust decreases as altitude increases during maintaining the same speed,and as result of that the fuel consumption decreases also.Mathematical calculations shows that at 11 km a jet engine develops 41% of the thrust at sea level.So the turbojet engine performance is more efficient at a higher altitude,but that requires a longer runway to attain the take-off speed

Influence of Radiation on Non-Darcy Mixed Convection Along a Non-Isothermal Vertical Plate in a Porous Medium With Thermal Dispersion and Viscous Dissipation

Saddam Atteyia Mohammad

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 85-101
DOI: 10.33899/rengj.2015.101032

A boundary layer analysis is presented for the interaction of non-Darcy mixed convection with thermal radiation along a non-isothermal vertical flat plate embedded in a saturated porous medium with thermal dispersion and viscous dissipation. The governing partial differential equations are transformed into a nonsimilar boundary layer equations. These equations are solved numerically by a finite difference method. The obtained results are checked against previously published work on special case of the problem and is found to be in excellent agreement. A parametric study illustrating the influence of the various physical parameters on velocity and temperature profiles as well as the local Nusselt number are conducted. It is obtained that as the value of the power law index, thermal dispersion parameter, and radiation parameter increases the value of the local Nusselt number increases. As the value of inertia parameter and viscous dissipation parameter increases the value of the local Nusselt number decreases.

Investigation the natural convection heat transfer between two fluids inside square enclosure separated by thin plate

Amir S. Dawood; Raed Ahmed Ali; Ramiz Ibraheem Saeed

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 102-113
DOI: 10.33899/rengj.2015.101040

Fluid flow and heat transfer in a square enclosure diagonally divided by a conductive thin plate has been numerically investigated. The upper diagonal zone of the enclosure filled with a saturated porous medium while the subdiagonal zone of the enclosure filled with air as working fluids. The enclosure was heated partially from below and cold from upper surface isothermally while the two vertical surface are insulated. The governing equations are solved using finite difference methods. Results were obtained for different value of Rayleigh number (103 ≤ Ra ≤ 105) for air and different value of modified Rayleigh number (100 ≤ Ra* ≤ 500) for porous medium as well as different dimensionless length of the heated surface (0.2 , 0.4 , 0.5 and 0.6 ). The results show that the increasing in Rayleigh number in both sides of the enclosure (Ra* & Ra) causes increasing in the Nusselt number. The percentage increasing is approximately is (92% at Ra*=100, 1000≤ Ra≤105 and 71% at Ra*=500, 1000≤ Ra≤105 for S=1 ) and ( 90% at Ra*=100 , Ra=104 and 0.2≤S≤0.6 and 80% at Ra*=500 , Ra=104 for 0.2≤S≤0.6 ). The flow become multi-cellular in porous media side also the increasing in dimensionless length of the heated surface causes increasing in the Nusselt number.

A preparation and Characterization of Functionally Graded Aluminum Alloy Based Composite Via Casting Route

Abdulhaqq A. Hamid; Mohammed M. Abdullah

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 114-128
DOI: 10.33899/rengj.2015.101044

In the current study, stir and centrifugal casting apparatus have been designed and constructed for the preparation of cast functionally graded aluminium alloy(AA4043) based composites containing Silicon Carbide (SiC) reinforcement particles. Hardness of different cast functionally graded composites (FGCs.) processed with different rotating speeds have been investigated. Unreinforced base alloy and cast gravity composite corresponding to the composition of matrix alloy of cast FGCs have also been cast and characterized for the purpose of comparison.The present study aims to understand the influence of rotating speed of mould on the reinforcing particles distribution and hardness of the resulting cast FGCs. It was found that increasing the processing speed of mould increases the level of distribution of reinforcing particles from the inner to the outer region. At a given processing speed, hardness increases significantly with increasing the radial distance for the both top and bottom surfaces and could be attributed to the segregation of the reinforcing particles at the outer region.

Design and Simulation of Ultrasonic Metal Welding Horn

Ziad Shakeeb Al-Sarraf; Margaret Lucas

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 129-141
DOI: 10.33899/rengj.2015.101045

Ultrasonic metal welding (USMW) has become an efficient technique covers a wide range of applications of metals. Because of recent light weight of the parts, an efficient technique like (USMW) has become more applicable, because it considers more accurate, more minimised welding method than before. Welding horn must be designed on satisfying many criteria: vibrate longitudinally at operating frequency, isolated the axial mode from other nearest vibration frequencies, uniformity of vibration amplitude at the working surface and high amplitude of the operating mode. This research presents an approach to the design and simulate of the horn configuration which satisfies these criteria. The simulation and vibration mode shape characterisation of the horn is discussed and the analysis is accomplished using FE-package (ABAQUS), whilst the vibration modes are classified using experimental data from 3D laser Doppler vibrometer measurements. Modal and harmonic analysis are completed successfully to examine the frequency for the welding tuned horn.


Husham J. A. Alqaysi

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 142-153
DOI: 10.33899/rengj.2015.101046

The focus of this paper is to implement a simulator for the Direct Sequence - Code Division Multiple Access (DS-CDMA) communication system and test its performance against certain parameters using the VisSim/Comm Version 6.0.03 software. In this paper, the communication system is considered to consist of a number of users each of which generating binary data of specified rate and is assigned a unique code. There are many major system aspects that associated with the design of a spread spectrum system need to be considered. One of these very important concepts is how to evaluate the performance of the system. The main evaluation method in the simulator for system evaluation is the measurement of the Bit-Error-Rate (BER) for various conditions that are essential in the DS-CDMA design and implementation.

Design of Broadband Microstrip Patch Antenna for WLAN/WiMAX Applications

Yessar E. Mohammed Ali; Khalid A. Sultan Jasim

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 154-163
DOI: 10.33899/rengj.2015.101047

In this paper design of a broadband printed microstrip patch antennasuitable for wireless communication (WLAN/WiMAX) applications is presented. The antenna occupies small size of 50×40×1.6〖mm〗^3. Parallel slots and corner notch are employed in a rectangular patch to achieve broadband characteristics.Two parasitic elementsare printedon the bottom surface of the substrate to givegood performance.The proposed antenna has return losses of -32 dB and -30.8 dB at 2.4 GHz and 3.5 GHz respectively. The bandwidth is 1.768 GHz (from 1.985 GHz- 3.753 GHz) at S11< -10 dB.The maximum gain is 2.8 dBi for 2.4 GHz and 3.3 dBi for 3.5 GHz. Thesimulated results are obtained using the software computer simulation technology CST. The designedantenna is printedat a low cost on FR-4 substrate and simple feeding using microstrip line feed.

Optical Fiber Nonlinearity Estimation Through Four-Wave Mixing

Tariq A. Al-Jumailly

Al-Rafidain Engineering Journal (AREJ), 2015, Volume 23, Issue 1, Pages 164-169
DOI: 10.33899/rengj.2015.101048

Optical wavelength converters are very important devices in optical
Dense Wavelength Division Multiplexing (DWDM) Systems. Among numerous wavelength technologiesFour-Wave Mixing (FWM)in optical fibers is attractive because it offers strict transparency to amplitude, frequency and phase. They also have the ability to convert multiple wavelengths simultaneously and to invert optical spectra. Four-wave mixing conversion efficiency depends upon fibernonlinearity.
The effects of fibernonlinearity play a decisive role in the design and performance of modem optical communication links.So it is important to measure the nonlinear promising technique for determining fiber nonlinearity (γ).This paper investigates a way of estimating fiber nonlinearity through four-wavemixing process.