Print ISSN: 1813-0526

Online ISSN: 2220-1270

Volume 19, Issue 2

Volume 19, Issue 2, Winter and Spring 2011, Page 1-145


Dr. Anmar A.M. Al-Talib; Ruaa Faiz M. Gadawi

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 1-10
DOI: 10.33899/rengj.2011.27035

Energy is required for pumping water in the irrigation pipe distribution networks. The need for this energy and its cost are continuously increasing due to the on-going expansion of the Arab countries in general and the Gulf countries in particular in using modern irrigation systems in their agricultural irrigation projects. Most pumped pipe-networks designed on hydraulic basis only without paying attention to the cost of power, thus huge loss in energy and capital needed for projects operation occur Sometimes. The design is based on economical basis without taking hydraulic aspects into consideration which results in low performance efficiency of the system or damage to the pipe network and consequently high maintenance costs.
The paper presents computerized mathematical model for optimal design of main pipe distribution networks of sprinkler irrigation system using linear programming. The pressure head at the inlet of the pipe distribution network is assumed unknown, thus the objective is to minimize the sum of the initial cost of the pipe network and the cost of energy for pumping.
The constraints included the minimum and maximum pressure head at all points along the pipes of the network in addition to the flow rates requirements within the network and at the inlet of each farm .
The study revealed that using the proposed model in the design assuming unknown inlet pressure head to system has resulted in 9.32% saving in the total cost of the network compared to the existing design which is based on known inlet pressure head for a selected irrigation sector inside a large planned irrigation project near Mosul city, northern Iraq.
Key words: Optimal Economical Design, Irrigation Pipe Network.

Verification of Scale Effect of Shallow Foundation in Determination of Bearing Capacity of Sandy Soil

Dr. Hussein M. Al.Khuzaie

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 1-11
DOI: 10.33899/rengj.2011.27328

The strength parameters for sandy soil are not depending mainly on level of stresses but they are a linear function of width (B) and embedment depth (u) of footing in Terzaghi's solution of bearing capacity. On the other hand, it was found by as called the non-classical solution conducted by Parkins and Madson (1997) that this relation is nonlinear and the bearing capacity for sandy soil is mainly relating to width and depth of foundation, which is known as scale effect. In this work a field model test was carried out on compacted sandy soil bed for different types of footings with different sizes and geometry for clarification of the two aforementioned approaches. It was found that two approaches are consistent and indicating the scale effect well for bearing capacity of sandy soil. On the other hand, from the field model tests results, it is found that the two determinations give overestimated bearing capacity values, especially for rectangular footing with length to width ratio more than 5 (L/B > 5) specially by Parkins and Madson's approach rather than the Terzaghi's equation.

Overland flow hydrograph in ungauged Catchment around Mosul city

Dr. B. Kh. Dawood; Y. N. Saeed; Sh. H. Dawood

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 11-27
DOI: 10.33899/rengj.2011.27037

Five catchment areas around Mosul city have been selected ( Khoser , West of Talkief , north of Qayara , Rabeea , and Badosh ) , there were no gauging station for the surface runoff measurements. Unit hydrograph of ( 3 hr ) duration by using three models , Nash , Clark , and Saint-venant are used to draw the hydrograph.
The results obtained showed that the Nash and Clark models gave closed results while the ratio between the peak discharge of Saint-venant to peak discharge of Clark and Nash are ( 2.5-27.4 ) , ( 1.14-36.23 ) respectively for different catchment.

Key words : IUH ( instantaneous unit hydrograph ) , Nash and Clark models , Ungauged catchment.


Abdulrahman H. T. Al-Zubaydi

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 12-28
DOI: 10.33899/rengj.2011.27331

This work aims to study the effect of erosion on the strength, loss in weight and gypsum dissolution of gypseous soil stabilized with (4%) lime, take into account the following variables: initial water content, water temperature, soaking duration or flow duration and water velocity. The results indicate that, the unconfined compressive strength decreased for samples soaked in water have low temperature (50 and 250 C), further decrease in strength with increasing soaking duration. The higher water temperatures (490 and 600 C) showed increasing in the unconfined compressive strength. High water velocity causes decreasing in unconfined compressive strength, more loss in weight and more loss in gypsum content, for all values of flow duration and water temperature.

Determination of Bio-decay Coefficient of Disposed Activated Sludge from Wastewater Treatment Plant in Medical Assembly of Mosul City

Ahmed Y. Shehab

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 28-37
DOI: 10.33899/rengj.2011.27039

This research, has dealt with determination of bio-decay coefficient of activated sludge disposed from wastewater treatment plant of medical assembly in Mosul city. four bench scale reactors were used of 2.25 liter capacity for each as aerobic digestion units. Throughout the operation period which lasted for a month temperature was controlled and it was (15, 20, 25, 30) ċ in the first second third and fourth reactor respectively, the bio-decay coefficients was found as (kd15=0.02, kd20=0.03, kd25=0.04, kd30=0.05) d-1 , while the temperature constant (θ) was (1.059). Also the results showed that the required periods for aerobic digestion process to reduce 50% of biomass concentration in the reactors at digestion temperature (15, 20, 25, 30) ċ were (17, 7, 5, 4) days respectively.

Using Crumb of Tyres in Hot Asphalt Mixture as Part of Aggregate

T. M. A. Al-Ani; Th. Y. Ahmed; W. M. Mahmood; S. M. A. Al-Ani

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 29-39
DOI: 10.33899/rengj.2011.27335

This study have used crumb of tyres in asphalt mixture as apart of aggregate. Three sizes of grade of crumb tyres were used in asphalt mixture (No. 4 (4.75 mm), No. 8 (2.36) mm and No. 50 (300µmm)). Three percentages of asphalt cement (4, 5 and 6) by weight with three percentages of crumb tyres (2, 4 and 8)% by weight were used with aggregates for preparing asphalt mixture specimens. Asphalt mixture specimens were prepared according to Marshall methods ASTM (D-1559). Thirty six specimens were prepared for evaluating Marshall properties (Marshall stability and flow, air voids percentage, bulk density, maximum bulk density, and Marshall Stiffness). Indirect Tensile Strength test (ITS) ASTM (D-1075) at 25oC has been used for evaluating resistance of asphalt mixture for cracking. For this purpose twenty four specimens were prepared for evaluating cracking resistance of asphalt mixture contain crumb tyres as part of aggregates. The study showed that the crumb of tyres has more effects on the performance of asphalt mixture by increasing the Marshall stability, flow, air voids, and decreasing bulk density and indirect tensile strength.

Studying and improvement of Laser Diode Driver performance at 1Gb/s in optical communication system

D. Luqman Sufer Ali; Marwan Abdulkhaliq Thannon

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 38-49
DOI: 10.33899/rengj.2011.27042

The Laser Diode Driver (LDD) is an important part in optical communication system; it acts as an interface between the data source and the optical source (Laser). The design of this circuit using CMOS technology which has low conductivity (gm), (less than from bipolar technology), is a challenge for designers especially at high data rate (>1 GB/s) because LDD must provide high current swing to obtain large optical output power.
In this research a simulation software using Personal Simulation Program with IC Emphasis PSPICE (2006) is used to study the performance of the LDD circuit using (0.18µmCMOS technology) at (1 GB/s), the peak to peak jitter is (110ps). In addition analyzing an automatic power control circuit, so that when changing the temperature from (0 – 80˚C) the Laser current changing is (5mA), and an improvement of reference voltage circuit has been added, since a constant voltage (319mV) achieved when the power supply voltage changes from (2.15-6V).

Keywords: Laser Diode Driver , pre-driver , Extinction Ratio.

Evaluation of the Acceptance of the Hot Mix Asphalt Paving Mixture Using Backpropagation Artificial Neural Network

Mohammed Y. Taha

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 40-54
DOI: 10.33899/rengj.2011.27341

The asphalt content in hot mix asphalt paving mixture is a key factor in producing quality pavements. In recent years, the artificial neural networks approach has attracted wide attention and found a growing number of pavement applications. This paper explores the feasibility of using the backpropagation artificial neural network with sigmoid function as activation function by MATLAB 7.8 software to determine the acceptability of the hot mix asphalt paving mixtures based on the percent of asphalt content and aggregate gradation using their Marshall properties. Several networks architectures, using two hidden layers with different numbers of nodes, are tested to obtained the best results.
The results showed that the network ( 10-20-10-3) had the best performance, and this network can be used as appropriated method for determining the asphalt content and aggregate gradation acceptability of hot mix asphalt paving mixture. This work concludes that the artificial neural network is a good method which can reduce the time consumed and can be used as a tool in evaluating the hot mix asphalt paving mixtures

FPGA Implementation Of Elementary Function Evaluation Unit Using CORDIC and Lookup tables

Basil Sh. Mahmood; Ehsan A. Ali

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 50-70
DOI: 10.33899/rengj.2011.27044

In this paper, a hardware computing unit has been designed and implemented. This unit computes many elementary functions (such as sine, cosine, tan-1, sinh, cosh, and square root) that their computing by using software systems requires thousands of clock cycles as an execution time. The architecture of the function computation has been designed by using VHDL and placed on XC3S500E FPGA chip in Spartan 3E as a target technique. In this paper, two algorithms have been used in computing the mathematical functions, because they can be implemented using FPGA chip. The first is the Coordinate Rotation Digital Computer algorithm (CORDIC) which was introduced in 1959. It is a single unified algorithm for calculating many elementary functions including trigonometric, hyperbolic, logarithmic and exponential functions, multiplication, division and square root. The second one uses the lookup table. According to the self-similarity in the trigonometric functions, and using the techniques of parallel pipelining for the CORDIC algorithm, speedup of (24.7 - 30.3)×100% is obtained as compared with the other parallel architectures. The throughput became operation/clock pulse except the first operation whose latency was 32 clock pulse.

Keywords: CORDIC, lookup table, Elementary Function, FPGA

Soft Handoff Parameters Evaluation in Downlink WCDMA System


AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 55-67
DOI: 10.33899/rengj.2011.27344

Mobility is an essential feature of mobile wireless communication systems. Handoff is a feature that deals with the mobility of the user in order to provide seamless phone call when the user cross the cell borders to another one. WCDMA system is the third generation system, implements soft handoff (SHO) technique while hard handoff (HHO) which is used in GSM system. Soft handoff is a technique which allows the user equipment in the overlap region to link with two or more base stations. The effect of soft handoff on the downlink direction of WCDMA will be studied because the downlink is considered as the limiting parameter in CDMA systems. The effect of soft handoff on the most important parameters of the downlink in WCDMA is investigated using simulation. Other related parameters of WCDMA system optimization such as load factor, noise rise, and parameters related to the quality of service like bit error rate (BER) are investigated. The results reveal that a user in soft handoff consumes less power from its serving base station. This reduction in the power leads to reducing the total interference in the cell and hence improving the performance of WCDMA system by reducing the load factor (loading) and noise rise, and increasing the capacity and enhancing the quality of service. Furthermore , the results assure why 2-way soft handoff is commonly used in CDMA system.

A Study Of Photoelectrical Characteristics Of (CdS/CdTe) Heterojunction

Bashar A.H. AL-abbasy

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 68-76
DOI: 10.33899/rengj.2011.27347

In this work, we report the photoelectrical properties of the (CdS/CdTe) structure as a function of the reverse bias voltage, light intensity and incident power wavelength. The investigated photodetection performance is located in the visible light spectrum situated at wavelength range (488-595 nm) and the maximum photocurrent at (505 nm).
The photodetection parameters such as quantum efficiency, responsivity, and detectivity have been studied as a function of incident power wavelength at different reverse bias voltages. These studies gave somewhat low values of such parameters which describe the performance of any photodetector

Identity Incarnated in Contemporary Arab Architecture the Architect Abed Wahid El-Wakil "

Dr. Asma Hasan Al-Dabbagh; Ekbal Salim Al-Sofee

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 71-92
DOI: 10.33899/rengj.2011.27046

Many of modern studies attached special importance to the phenomenon of incarnating the identity of Architecture. From this, Arab modern studies which was theoretical and practical, This research concentrates on the subject of identity of modern Arab Architecture and recognizes it, and comes out with theoretical framework by previous studies in this context. It appears that elements of theoretical framework relate to two types. Elements related to incarnation of identity in Architectural heritage, and elements related to incarnating identity in new products. Each type contained more subdivisions. The research application concentrate on some of framework items in practical study for testing it analytically, by choosing the Architect Abed Wahid El-Wakil to show his work.
The findings show special pattern to El-Wakil by depending on the strategy of searching for traditional roots in his new designs, which relate to certain values which are concurrent to theoretical framework. The conclusions answer research queries about El-Wakil , and confirm thinkers viewpoints of the phenomenon in generally, and to El-Wakil especially. The findings outline a guide to architects who want to follow the pattern of El-Wakil for incarnating the identity of modern Arab architecture in their new design.
Keywords: Contemporary Arabic Architecture, Architectural heritage, incarnating identity, Abed Wahid El-Wakil.

Effect of Size and Surface Roughness of Cylindrical Weirs on Over Flow Characteristics

Ibrahim A. I. Al-Hafith; Tahssen A. Chilmeran; Khalil I. Othman

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 77-89
DOI: 10.33899/rengj.2011.27351

weirs are the most commonly used device in channels for flow measurement and flow regulation due to its simplicity. Conventional rectangular, triangular and trapezoidal weirs are among the most common oldest types of weirs, progress ogee crest weir and cylindrical weirs are started to use in hydraulic engineering. The advantages of the circular weir shape are the stable overflow pattern compared to sharp-crested weirs, the ease to pass floating debris and the simplicity of design. The concern of this paper is to study the effect of size and surface roughness of cylindrical weirs on discharge coefficients (Cd) under different flow conditions.
The work was conducted in experimental flume by using three sizes of cylinders and three types of surface roughness. The obtained results show that Cd values will increase with increasing flow rate as well as with decreasing in cylinder diameter; an increase in surface roughness of weir can makes great reduction in Cd value. The h/R effect on Cd values increase with increase in cylinder diameter. An empirical relation was obtained to estimate the coefficient of discharge Cd under different size and surface roughness of cylindrical weirs.

Growth and Reduction of Flexible Compositions in Architecture

Ghada M. Yonis; Shatha Y. Al-Sheikh

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 93-116
DOI: 10.33899/rengj.2011.27050

Growth is presented as one of the important properties which distinguishes flexible compositions .This property emerges in the middle of twentieth century in some architectural trends as a reaction towards a problem facing the designers, considering the production of compositions that can face rapid changes in design requirements over the time with preserving their architectural identity, however the architecture is a convertible phenomena . The article discusses the importance of this property and how it is achieved in architectural products . The framework of this paper consists 0f one main item (devices 0f achieving growth in flexible compositions) which determine growth ,firstly, then the application of this item on a sample 0f specialized architects , secondly ,finally ,extracting comprehensive description of that property in architecture . Conclusions have been declared, that growth is achieved by employing both formal and structural characteristics, considering cellular geometric shape with many similar fragments or cells which can expand and spread horizontally and vertically like organs, concentration on the principle of similarity (uniformity) in composing the fragments , with articulation as compositional relationships, as well as applying hidden orders based on modular clustered-grid composition ,traditional structure and zoning space system.
Keywords : growth , flexibility ,change, adaptability.

Particularity of practicing contextualism in university buildings

Bayda Hanna Saffo

AL-Rafdain Engineering Journal (AREJ), Volume 19, Issue 2, Pages 117-145
DOI: 10.33899/rengj.2011.27321

The concept of contextualism associated with the current architectural trends and it gained a positive value in the presentations and practices of post-modern stage as an tool for establishing a kind of mutual dialogue between architecture and the existing setting in town as a reaction towards modernism problems related with the loss of communication feature amongst architectural products. The research discusses the importance of this concept to explore the research problem represented by unclarity of particularity of practicing contextualism in university buildings. University buildings, are characterized by the variation of design practices in their different time periods, leading to dis-communication in the expressive languages. So, the research problem was crystallized and its method and objective were identified represented by the construction of a theoretical framework that includes three main items; namely, intellectual attitude of the designer towards the existing settings, the nature of the contextual dialogue references and the mechanisms accomplishing the contextual dialogue. Then Mosul university campus was chosen as a field. The theoretical framework was applied on selected architectural projects for both categories; academic and practitioner architects in order to compare the contextual practice for those categories. The results showed that the two categories are variant concerning the derivation of context as a dialogue between the different architectural products in the university campus according to the their intellectual backgrounds.