ISSN: 2521-9154

Volume 18, Issue 1

Volume 18, Issue 1, Spring 2015, Page 1-139


Flexure Revisited: Strength of Singly Reinforced Beams- A Simple Approach

Raid I. Khalel; Nisreen S. Mohammed; Sameh B.T. Shukur; Kaiss F. Sarsam

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 1-15

181 singly reinforced beam tests available from the literature are investigated to obtain two flexural design methods-one simple proposal and an alternative one that takes into account the influence of rising flexural reinforcement ratio on design. The simple proposal takes significantly less time to apply compared to the alternative one. The former leads to only 0.5% greater COV than the latter. These design methods are compared with four code methods (ACI 318M-11, 318M-99, BS and NZ codes).
Based on the ratio of ( being the calculated moment resistance), the two proposal methods give relatively low coefficient of variation (COV) values: 15.9% for the simple method and 15.4% for the alternative method. These compare to COV values of 17.5%, 15.9%, 15.6% and 15.7% for the ACI 318M-11, ACI 318M-99, BS and NZ methods, respectively.
One major advantage of the simple design method (Constant value of  = 0.85) is that all 181 tests lead to safe prediction.

Riverbed Scour Due to Accumulation of Floating Debris on Al-Msharah Bridge Piers

Zahraa Abdulhussain; Ala Hassan Nama

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 16-25

This paper aims to implementing and run a study hydraulic simulation model by using the HEC-RAS software to simulate the flow in AL-Msharah River and studying the effect of floating debris accumulation on Al-Msharah Bridge piers on the flow conditions upstream the bridges and estimating the scour development according to this effect.
All the required geometric, hydrological and riverbed material data were provided by Ministry of Water Resources, Iraq. These data were adopted for implementing the hydraulic simulation model. The effects of debris accumulation at the bridge piers were studied according to the present state of the river through considering six inflow discharge 5, 10, 15, 20, 25, and 30 m3/sec each with a range of floating debris dimensions (width, m × depth, m) up to (2m×2m).
Results of applying the implemented hydraulic model showed that accumulation of debris on the bridge piers for more than 1m×1m increase the water surface elevation upstream the bridge to about 1m with the case of maximum discharge of 30m3/sec and debris of 2m×2m and increase the flow velocity and changing the flow velocity distribution within the bridge cross-section by about 15 to 20%.
The total main channel scour depth increase from 0.77 m for the case of no debris with minimum discharge, 5 m3/sec, to 1.9 m for the case of 2m×2m debris with maximum discharge, 30 m3/sec.
According to these results it is recommended that accumulated debris on AL Msharah Bridge piers must be carefully monitoring when its dimensions became more than 1m×1m and it must be removed from the bridge piers when its dimensions become more than 2m×2m because the resulted scour damage the bridge.

Distribution of Shear Stress in the Meanders of Tigris River Within Baghdad City

Ala Hassan Nama

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 26-40

Distribution of bed and banks shear stress was studied considering the effect of bends on this distribution within the main three meanders, Al-Kadimiyah, Al-Atafiyah and Al-Jadiriyah in Tigris River within Baghdad City. A steady flow hydraulic model, using the HEC-RAS software, was used to simulate the flow in Tigris River within Baghdad City in order to obtain the flow characteristics in ten slices across the considered cross section along the river reach for the cases of 400, 800 and 1300 m3/s which represent the minimum, average and maximum discharge of the river flow during the period from 2000 to 2010.
The calibration and verification process was carried out using two sets of discharge and stage measurements. These processes showed that the Manning’s n values were between 0.025 to 0.028 for the main channel and 0.038 to 0.042 for the left and right banks and the water surface slope was 7 cm/km.
Application of the hydraulic model for the three cases of discharge (400, 800 and 1300 m3/s ) shows that the maximum and minimum flow velocity were (0.39, 1.11), (0.53, 1.13) and (0.57 and 1.37m/sec), respectively. While the water surface slopes varied from 6.5 to 8.5 cm/km for discharges between 400 and 1300 m3/s, respectively. These slopes increased at the bridges to about 9 cm/km.
Results of applying the hydraulic model were used to compute the shear stress in each slice across all the considered cross sections for the three meanders using the reach-averaged boundary shear stress equation and the Federal Highway Administration guidance was used to estimate the shear stress within the high shear stress locations. The Arc-GIS software was used to process the data by making use of the available interference facilities between the HEC-RAS and Arc-GIS softwares.
The estimated maximum shear stresses in the three bends for the discharges 400, 800 and 1300 m3/s showed that the meandering effect increase the maximum shear stress in Al-Kadimiyah, Al-Atafiyah and Al-Jadiriyah bends by about 16%, 22% and 31%, respectively.
The locations and distribution of shear stress in the case of considering the meanders effect at the upstream and downstream of the bends does not affect. While it is changed in the bend and become coincident with the characteristics of flow and river geometry. The influence of disparity in the values of shear stress appears through upgrowth of the islands within the river at the locations of low shear stress with continuous changes in the geometry of the river to be coincident with the distribution of shear stress.

Mechanical and Physical Properties of Glass Wool-Rigid Polyurethane Foam Composites

Aseel Kais Rasheed; Ismail Ibrahim Marhoon

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 41-49

This research is devoted to the preparation of foam polymer matrix composite materials by forming in place method, where the composite foam material was prepared from the rigid polyurethane foam (PU) as a matrix reinforced by glass wool insulator with weight fractions (2%, 4%, 6%, 8% and 10%) .Several mechanical and physical tests were done and these include impact, flexural, compression, hardness, density, water absorption and thermal conductivity. The result shows that the values of mechanical and physical properties in general are increased with the increase of glass wool weight fraction content. The values of flexural strength decrease with the increase of weight fraction of glass wool fiber after 8% wt.

Designing an Efficient WCDMA Compliant Fractional-N Frequency Synthesizer

Ismail Sharhan Baqir

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 50-60

In this paper, fractional-N PLL is introduced to generate 1.965 GHz according to WCDMA specification , where a proposed deterministic 4th order MASH structure that guarantees a long sequence length to be used with simple stochastic dithering at the last stage as a noise shaping technique achieving hardware budget compared with classical dithering that used long linear feedback shift register LFSR . Modulator in band phase noise is -100dBc/Hz within the loop bandwidth of 1MHz, the PLL lock time is less than 25 μs. C++ language is used in the simulation of the system behavior for all blocks of the synthesizer due to its flexibility and high speed of execution, then data is post processed using MATLAB R2011a.
The proposed MASH structure consumes 89% FFs and 90% LUTs of the Dithered MASH reported in ref.[9] for identical number of bits achieve significant hardware cost reduction.

The Effect of Different Water Solution on the Electrical Conductivity of Polyester Reinforced With Waste Aluminum

Shayma H. Mohammad

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 61-65

In this work, we studied the electrical conductivity behavior of waste Al reinforced polyester composite material in different solutions (distilled water, tap water &3.5%NaCl) with a weight fraction (5, 15, 30 &45) was investigated for (6) weeks immersion time. The results exhibited that increasing in electrical conductivity with increasing in immersion time, also Maximum value of electrical conductivity was recorded at immersion in 3.5% NaCl solution. However electrical conductivity increases with increasing in weight fraction of waste aluminum due to opening path of electrons thus electrical conductivity will be increased.

The Effect of Magnetic Abrasive Finishing on the Flat Surface for Ferromagnetic and non-Ferromagnetic materials

Ali H. Kadhum; Yahya M. Hamad; Nazar Kais M. Naif

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 66-75

Magnetic Abrasive Finishing (MAF) is an advanced finishing method, which improves the quality of surfaces and performance of the products. The finishing technology for flat surfaces by MAF method is very economical in manufacturing fields an electromagnetic inductor was designed and manufactured for flat surface finishing formed in vertical milling machine. Magnetic abrasive powder was also produced under controlled condition. There are various parameters, such as the coil current, working gap, the volume of powder portion and feed rate, that are known to have a large impact on surface quality. This paper describes how Taguchi design of experiments is applied to find out important parameters influencing the surface quality generated during MAF method. In the experimental part, two types of materials from non-ferromagnetic and ferromagnetic (Aluminum alloy 7020 and stainless Steel 410 respectively) were considered with different parameters. Regressions models based on statistical-mathematical approach were obtained by using SPSS software for two materials.

Numerical Investigation of Power Plant Operates with Super critical Pressure Boiler

Kadhim Fadhil Nasir

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 76-83

Numerical investigations were made of heat transfer to supercritical water flowing in a boiler vertical tube. A comprehensive set of data was obtained for pressures from 22.09 MPa to 25 MPa, mass velocity 250-400 kg/m2s, the results are bulk temperatures from 345°C to 445°C, heat fluxes from 150 to 800 kW/m2, tube diameter was 48 mm. The steady thermal model for cross section of water wall tube was established. Heat flux and temperature of working fluid are determined by using Fortran computer program at each section of the tube length. The heat transfer coefficients show behavior depending upon the heat flux. the power of plant, boiler efficiency, and plant efficiency was determined at different mass velocities, we found that the boiler
and plant efficiencies increasing with the increasing of power of plant. The comparison between this investigation results and the results of other sources, we found good agreement between literatures references and numerical results of this study.

Studying the Mechanical Properties of Epoxy Carbon Nanotubes Composite

M. I. Mohamed; N. J. Saleh; L. H. Mohmoud

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 84-90

In the present work a modified chemical vapor deposition method (CVD) was adopted for the production of carbon nanotubes (CNTs), Scanning Electron Microscope (SEM) was used for identification of these of carbon nanotubes. The identification revealed two types of carbon nanotubes Single wall (SWCNTs) and nanocoils tubes. These nanotubes were successfully employed in the development of bulk composites, where commercial epoxy resin has been used as matrix, while mixed phase of carbon nanotubes served as reinforcement phase. It was observed that a substantial increase in all mechanical properties: hardness and Young modulus as well as the thermal properties from which Tg curves were recorded, consequently Glass transition temperature Tg was determined.

Cathodic Protection of Carbon Steel Using Aluminum as Sacrificial Anode in Sea Water

Muayad Fadhil Hamad

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 91-100

The effect of Aluminum as sacrificial anode in seawater (3.5% NaCl) of PH=6.8 was investigated under flow conditions (0-0.262 m/s) for a range of temperatures (25-45°C) using rotating cylinder electrode. And different area of Aluminum at distance of 6cmwere used to protect steel from corrosion, these were A1=2*2cm2, A2=4*4cm2 and A3=8*8cm2 under stationary and flow conditions... It is found that the corrosion rate of carbon steel increases with flow velocity when it free and when coupling with Al it has unstable trend with temperature but also the corrosion rate of Fe decreased after coupling. Using small area of Al increase the corrosion rate while using large area will not highly effective on corrosion rate of Fe. The protection percent of Fe increases appreciably (shifts to more positive) with increasing rotation velocity. It shifts to more negative with increasing temperature.

Adsorption of Thiophenic Compounds from n-Hexane Using Activated Carbon Adsorbent

Yousra Saber Kareem

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 101-110

The aim of this work is to study the adsorption of thiophenic compounds (thiophene and benzo thiophene) on activated carbon by studying the effects of various important variables such as height of the bed (4, 6, and 8 cm) , inlet sulfur concentration (50, 75, 90, and 100 PPM), and flow rate of the liquid n-hexane feed (4, 13, and 20 ml/min.).
The activated carbon has very high affinity for the sulfur compounds in the order benzo thiophene > thiophene. In Fixed bed experiments the concentration of sulfur out (Co) with time decreases with increasing of bed height, flow rate, and the initial concentration of sulfur compounds. The maximum percent removal of thiophene was reached to 70% at initial concentration 50PPM at bed height 6 cm and feed flow rate of 4 ml/min., while the maximum percent removal of benzo thiophene was reached to 73% at initial concentration 75PPM at bed height 4 cm and feed flow rate of 4 ml/min.

Design of a Spray Tower for the Granulation of Melt

Kaiser Muslem Abd Ali

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 111-117

In this paper a simulation of cooling-solidification tower was presented, sprayed droplets is one of major methods for prilling of melt. Traditionally, this is carried out in an empty tower, and the equipment requirements for producing larger particles is very high, for analysis and simulation, mathematical model of tower, the effect of molten drop size on height of tower, heat and mass transfer coefficients are estimated according to empirical correlations. Estimations are considered based on concept of energy and mass transfer correlation equations. The results showed that the height of equipment is greatly affected by atomized particle size.

Efficiency of Optical Non-Destructive Testing Method to Detect Surface Defects in Engineering Materials

Leena Fahad Fattak

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 118-127

Measuring of surface defects of engineering materials represent one of great importance engineering applications. The efficient use of detection of surface defect methods helps to avoid unreasonable high demands being made on surface quality.
In this work, a simple laser system technique was used to detect the superficial defect. This is done through by the assessment of the laser light signals which are reflected from the work piece surface and detected by the photo diode detector. Theses signals are translated into final results which are corresponding to the type, geometry and dimensions of defects. An experimental arrangement using He–Ne laser light with measured maximum output power 4.5 mW and wavelength of 632.8 nm was incident on a sample, by using two convex lenses to collimate the light. The incident light was reflected and it was detected using the photo diode detector in the electronic analyzer circuit.
Three different shapes of defects (conical, pyramid and scratch defects) were prepared on the two different materials (aluminum and iron). From the results, because of the total scattering of light, the defects have been identified through the detection and analysis of the intensity of the reflected rays, where the effect of pyramid defects was high.
Optical methods were extremely useful for Non Destructive Testing (NDT) due to their ability to measure fast and contactless, to test larger areas or tiny spots in a short time, and to measure on complex shaped parts as well as plane surfaces.
Finally, this paper describes the advancement of NDT towards a quantitative evaluation of the geometry and location of defects.

Effect of Surface Roughness Height on the Aerodynamics Performance of Axial Compressor Cascade Blades

Assim H. Yousif; Jafar M. Hassan; Omar A. Khudar

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 128-139

The performance of fluid handling mechanical parts such as compressor blades are usually significantly affected by the surface roughness, because they often operate in condition of peak output that is close to this flow condition. The influence of surface height roughness of compressor blades has been investigated experimentally under the effect of cascade stagger angle. The experimental results done by using the direct measuring technique showed that the aerodynamic coefficients of compressor cascade blades influences by presences of surface roughness and stagger angle. The lift coefficient, pitching moment coefficient and cascade blade efficiency were reduced, while the drag coefficient is increased, with the increase of height roughness. The height of roughness does eliminate the operating condition of the cascade blades, which reduce the value of the stall angle.

The Role of Sound Pressure Level and Sound Types in achieving Comfortable acoustic environment for city centers (Al-Karrada as selective district in Baghdad city)

Susan Abed Hasan

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 1-18

The Acoustic environment represents all the sound that surrounds mankind and that it can interact with the daily life and communicate with members of the community. The importance of acoustic environment in urban centers cause of the diversity and plurality of the sounds resulting from human activities of daily life. This requires designers and urban planners give the required importance in the design of the acoustic environment of cities and in accordance with the requirements and objectives of the present era. This research submits a hypotheses question about the role of sound pressure levels and types in human evaluate the comfortable in acoustical environment for city centers, the research hypotheses is that sound pressure levels and types are important in achieving the comfortable acoustic environment for city centers and for city of Baghdad specifically. This research based on analytical methods and study fielded measurements for sound levels pressure as a first stage, an intensive questionnaire survey was carried out for the recipient in the sound environment as a second stage to submit their of sound environment and the acceptance for it. Al- Karrada district in Baghdad city was choice as an example of the pattern of the acoustic environment in the center of Baghdad, which uses varied between residential, commercial and administrative. Search results showed the presence of high proportions of sound levels generated by the voices of motor vehicles and construction works affecting negatively in the acoustic environment comfort according to the standards measurement accepted levels of the noise, and then its impact on the social aspects of the environment and economic development. Then search made a number of conclusions and recommendations for planners and urban designers to provide a comfortable acoustic environment in urban centers in general and the city of Baghdad specifically.

The Objective Attitude in Architectural Academic Local Research

Nawfal Joseph Rizco; Suha Hassan AL-Dahwi

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 19-44

Objectivism is viewed as a concept adherent to the theoretical Frameworks or to the research abstracts achieved within the academic limits and owing to the fact that the research in Architecture is conclusive in general and its academic aspect in particular of topics that fall within the scopes of natural and human sciences that have different methodological research . The dilemma of the obscurity of the objective nature of the formulated theoretical Frameworks arose to this connection , for objectivism as a concept differs according to the intellectual stances adopted by researchers or in other words according to the logic adopted by those researchers in realizing their accomplish researches ( formulating their theoretical Frameworks ). From this point the research dilemma arose and substantiated by the obscurity of the relationship between objectivism as a concept adherent to the researches or to the academic theoretical Frameworks (research resultants) adherent to the ideological stances adopted by those researchers. Consequently, need aroused to a definition of concept of objectivism and its relationship to researchers' ideological, intellectual stances , hence this research endeavored to demonstrate what is meant by objectivism in its attitudes, indicators , different levels and the foundation upon which each attitude relies and then to revise the ideological characteristics of Research in architecture in general in order to conclude its stance respective to the objective attitudes' characteristics as based on previous studies and surveys that tackled the research of architecture in general. Due to few reference available which approach the topic of objectivism in research realized in Architecture specialty within the academic and local limits in particular; researcher launched on concluding the ideological characteristics that differentiate the Research in Architecture by superposing or matching them with the ideological characteristics that distinguish the objective attitude in particular in research abstracts or researches accomplish in Architecture, especially in Architectural subjects that falling within the scope of ( what is ought to be) a large part of which affiliates to human science field in an introduction to verifying the realization of those characteristics in a number of research samples relevant to local academic architectural Researches,i.e.( Ph.D. Theses researches ). Among research resultants was the conclusion of a group of ideological characteristics that can identify the objective features of local academic architectural research and state that there is some kind of multiplicity of objective attitudes adopted by researchers according to their intellectual stances within the same research as it became evident and identical from the conclusions that the objective attitude features of one research is related to the researcher intellectual stance.

Effect of Calcium Hardness on Corrosion Rate of Domestic Water Galvanized Steel Pipes

Atia; Mohammed Hussein J. Al

ALNAHRAIN JOURNAL FOR ENGINEERING SCIENCES, Volume 18, Issue 1, Pages 45-53

Galvanized steel pipes are the main material in the implementation of domestic water distribution networks throughout Iraq. To study the variables affecting their corrosion, mathematical relationship for the calculation of corrosion rate was derived in terms of dissolved oxygen concentration, flow velocity and temperature based on the principles of mass transfer and electrochemistry , to add the effect of the calcium hardness to this relationship, experiments were conducted for measuring the corrosion rate in a straight 18.5 mm ID pipe flow of water at velocities ranged between 0.18 and 1.21 m/sec for three types of water (hard , moderate and soft). The results Shows the importance of calcium hardness on inhibiting corrosion process for more than five times in hard water compared to that in soft water also an exponential relationship between calculated to experimentally corrosion rate and calcium hardness concentration was obtained. Introducing this relationship as a correction factor for derived relationship sounded the accuracy of calculated corrosion rate results up to more than 90%.This relationship could expect and explain the disparity in the service life of these networks.