Al-Rafidain Engineering Journal (AREJ)

ABSTRACT
The main purpose of drainage is to provide a root environment that is suitable
for the maximum growth of plants. This study is conducted to find the drain spacing
using dynamic equilibrium concept for four different soils with different drain depths,
and compare the results with those obtained for the peak irrigation period and the steady
state equations using arithmetic, geometric and exponential means.
The study included soil texture and hydraulic conductivity tests for four different
soils. The drainable porosities of soils were found from especial curves. Two crops were
chosen(maize and cotton) and their water requirement and growing season were
estimated from previous studies. A computer program was made to obtain the drain
spacing using the previously mentioned methods. The drain spacings obtained with the
dynamic equilibrium concept were higher than those obtained with the peak irrigation
period .The difference in drain spacing becomes more evident with greater depths and
higher values of drainable porosity. The drain spacing required for maize is higher than
that for cotton. This means that the spacing is affected by both soil type and crop

Abstract
The investigation aims to study the effect of re-vibration time and amount of steel
fiber on the properties of concrete made with crushed cement-sand mortar as coarse
aggregate. Three mixes were prepared with 0.00, 50 and 100 percent replacement of
natural gravel by crushed cement-sand mortar aggregates. Mix proportions of concrete
were 1: 2: 3 by weight. The water cement ratio of 0.50 to 0.60 was used to obtain the
same workability for all mixes throughout the research. The specimens were cast to
investigate compressive and splitting tensile strength of concrete.
The results showed that concrete made of crushed cement-sand mortar as coarse
aggregate had lower workability than concrete made with natural gravel aggregate for
the same water cement ratio. This reduction in workability is reduced for the richer
mixes and the influence of coarse aggregate on the workability decreases with an
increase in the amount of cement in the mixture. Concrete compressive and splitting
tensile strength were improved due to re-vibration by about 19 percent at the peak value
(about one hour after initial vibration) with volume fraction of steel fiber of about 0.5
percent. The steel fibers improve the compressive strength of concrete by about 8-11
percent and the splitting tensile strength by about 10.3 percent for the same period of revibration.

ABSTRACT
In this research an evaluation of the ground water quality at the area located on
both sides of Tigris river in Mosul city. Where thirty wells were had been chosen and
water samples were taken monthly for chemical and physical tests (pH، temperature،
Ec، COD & BOD)، from each well for period from October 2001 to May 2002.
Coliform bacteria test were done for all wells during November and February. The
computer program Surfer 32 is used for preparing a topographic map and contour
maps depending on the data obtained. For the evaluation of ground water quality a
computer program in( Visual BASIC) were made to analyze the collected data.
The result of this research shows that the ground water are polluted with coliform
bacteria, it means that the ground water polluted by recharging sewage water.There is
a high concentrations of salts and organic material in the ground water.Also the results
of the analysis showed that the quality of the ground water were improved during the
period of the raining season

Abstract:
The Effect of strain on the elasticity modulus and moment capacity of
members are studied using different types of stress – strain relationships (linear,
elasto-plastic, elastic perfectly plastic, bi-linear, tri-linear and other continuous
models) for bending with or without axial loads using the steps of solution shown
in the research.
Generally in all cases inelastic modulus reduced with increasing the strain
and stress level and significant decrease is occurred in the value of inelastic
modulus, the value of inelastic modulus reduces to about (50%) of its initial value
when the stress value within (0.4-0.5) of the yield strength. Effect of stress ratio
(RF) and strain ratio (Rε) are also studied. Suitable equations are proposed to
estimate the values of inelastic modulus and moment capacity

Abstract:
This research aims at investigating the economics of domestic solar hot water
systems in order to promote the use of such systems in Iraq in spite of the low
prices of the natural energy sources. The integrated collector storage system,
suggested by Kahwaji, is adopted in this study due to its simplicity and good
thermal performance especially with respect to nighttime heat loss.
Thermal and economics analysis indicated that the system can provide
savings of 49 %, 56 %, 35 % and 58 % in the domestic hot water energy
expenditure in the environment of the cities of Mosul, Baghdad, Basrah and Ratba
respectively when 20 % inflation rate for the price of electricity and a system life
time of 20 years are used.

Abstract:
Modeling a hydrologic time series has been one of the most complicated tasks
owing to the wide range of data, the uncertainties in the parameters influencing the
time series and also due to the non availability of adequate data. Recently, Artificial
Neural Networks (ANNs) have become quite popular in time series forecasting in
various fields. This paper demonstrates the use of ANNs to forecast Khabur monthly
river flows for flow data from January 1958 to December 1975. Using the feed
forward network. The network is trained using the lagged or delayed variables from
SARIMA model as an input variables for the network. ANN model for mouthy flow
gives better result in comparison with Traditional ANN models and SARIMA model.

Abstract:
Multiuser detection is the demodulation of signals of different users interfering
with each other. This phenomena known as multiple access interference occurs mostly
in code division multiple access (CDMA) systems. In this paper the study and
analysis of the blind adaptive multiuser detection algorithm is achieved for directsequence
code division multiple access (DS-CDMA) communication systems. The
goal is to obtain multiuser detectors that require only knowledge of the signature
waveform and timing of the desired user. Comparison is performed of the blind
adaptive technique with the conventional detector (matched filter detector) or (M.F.D)
in perfect power control and in the presence of the near-far effect. In the present
simulation, the blind adaptive multiuser detection showed an excellent bit error rate as
compared to the conventional detection with the same requirements. Also the blind
detector showed an immunity towards the near-far problem. In this simulation the use
of adaptive variable step size is used in contrast to the constant step size shows
improvement in speed convergence and stability of the algorithm adapte

Abstract:
In ultrasonic defect sizing using the maximum echo amplitude technique,
the reflected echo signal height is taken to be related to the amount of ultrasound
propagated energy which is reflected from defects and to the information
contained in this reflected energy. In this investigation horizontal drilled holes of
known sizes are considered in grey cast iron which is usually treated as the most
difficult type of cast irons when ultrasonically inspected, due to its high sound
attenuated nature. The defects sizing results obtained from grey cast iron are
compared with those obtained from a steel of a similar pearlitic matrix structure as
a reference material. 2, 4, 6 & 8 mm drilled holes at known depths are prepared in
both grey cast iron and steel test samples. Maximum echo amplitude sizing
method is adopted, using both compression wave probes & shear wave probes of
1,2,4 & 6 MHz frequencies at different scanning positions. Although the results
are only limited to defect sizing in grey cast iron with reference to steel, they do