AL-Rafidain Engineering Journal (AREJ)

The need for use of cycloconverters is in controlling a.c motors at
low speed drive especially in high power application. The MATLABSIMULINK
model for three pulse, six pulse and twelve pulse three phase
to three phase cycloconverter has been constructed. The control strategy
of supplying the firing pulses is based on the cosine wave crossing
method. The SIMULINK model for the control circuits to perform the
procedure of this strategy has been constructed. A control circuit for each
thyristor to control its firing pulses has been constructed separately to
prevent any complexity in the control circuit. An R-L load was used. In
additional a three phase induction motor has been connected to test the
reliability of the system in controling the output frequency and then the
motor speed. The present study includes circulating current and semicirculating
current modes of operation with study of measuring and
correction of output power factor of the cycloconverter and output
voltage waveform harmonics.

To get accurate performance of the distance protection function,
Must be all influencing quantities and limitations on the measuring
accuracy of distance relay that imposed by power system in considered.
This research includes study and analysis of the problems which faces the
conventional distance relay which was designed for single circuit distance
protection when applied double circuit of over head transmission line,
due to mutual coupling zero - sequence system in this case, For various
operational conditions and fault location,This work had been conducted
with (I.N.R.G. 132 kV) transmission lines systems under to ground fault
condition, The current and voltage at the relay and fault location were
calculated.
The results show that zero sequence mutual coupling may cause the
distance relay to seriously over reach under reach for different operational
situations and fault locations, Values of short circuit levels ratio and
power flow for feed sources which connected to the line ends have major
effect in this problem.
This research indicate the possibility of zero sequence coupling
compensation by injecting proportion of the zero sequence current
flowing in the parallel feeder into the relay to reduce this effect, This
method is successful when relay and fault location are in the a same
circuit, Also when relay and fault location are in different circuits but
with limits .

Mosul University network which covers most of its departments
and colleges has been implemented in a star topology using fiber optic
cables and Cisco switches. In order to participate in optimizing the
network performance by minimizing broadcast and collision domains, a
proposed network (as an example) for the Engineering College based on
VLAN technique has been developed using the network simulator
software (OPNET IT GURU). The suggested model could be applied to
other colleges. The results being obtained represent the optimum possible
improvements in terms of node delay, throughput and minimizing
unnecessary traffic to avoid network congestion

Due to unlimited expansion of mobile communication devices,a rapid
increase in the exposure of people to radio frequency radiation has
occurred which in turn resulted in many questions regarding the
possibility of hazardous effects of these fields.
Although mobile phones are low-power transmitters but they are used
close to the user’s head.
In this paper, the specific absorption rate of the electromagnetic
energy absorbed in human tissues is examined for partial exposure and
inter-related to current radiation safety standards. Simulation of specific
absorption rate of electromagnetic power absorption in human head is
carried out for mobile phones of different antennas using CST-microwave
studio package.
The results showed that maximum permissible exposure limits for
“Safe Exposure” set by FCC are not reached. However these limits are set
on thermal basis and reflect the present understanding of these fields,
which are considered to be non-harmful for humans. On the other hand
there are complains from using mobile phones which suggests nonthermal
effect may exist. Further research in this area is needed to reach
clear evidence that existing safety guidelines govering exposure of the
public to the radiation employed in mobile telephony are adequate.

In this work , the influence of the location and depth of
transvernce cracks on the natural frequency of cantilever beam was
studied. The study of the cracked beam has been carried out
theoretically, starting from derivation of equation for the additional
strian energy in the presence of a crack .The equation of natural
frequency change due to the presence of a crack can also be calculing
for cantilever beam . The results showed that the presence of the crack
causes a decrease in the values of the natural frequencies of beam as
the decrease in the value of natural frequencies of the beam with cracks
in the area nearer to the supports, was lesser than in areas away from
the supports. Finally, the theroetical results were compared with the
experimental results of previous researches, which were in a cloce
agreement especially for the behavior of beam curves as function of the
crack depth.

In this paper a new algorithm has been developed to enhance
spatial structure by using texture feature extraction. Then, this algorithm
has been programmed and an integrated program has been prepared by
using Microsoft Visual C++ 6.0. In order to ascertain the usefulness of
this algorithm, it has been applied in two groups of images, the first group
consisted of three images of different feature. The results have been
evident enhancement in spatial; structure. The second group of images
consisted of multi-spectral images taken by Thematic Mapper (TM) in the
city of Mosul. The results of this algorithm have been used in the
classification.
The measurement of classification accuracy of the results of this
algorithm compared with the original images which have not undergone
any spatial structure enhancement revealed that this algorithm executed
the process of texture feature extraction excellently. Further, the results
were clear in the barren areas, Agricultural fields and the other areas as
well.

The research evaluated the fluoride concentrations by collecting
samples of drinking water twice a month through one full year. Then the
fluoride concentrations was measured and compared with the
recommended values set by international environmental and health
organizations .The results indicate that there is fluctuation in the fluoride
concentrations . It ranges from (0.075)mg/l to (0.225)mg/l with an
average of (0.147)mg/l . All samples concentrations are lower than the
guide values. Thus the water is suitable for drinking as far as this
characteristic concerned , with an expectation that dental caries cases may
be appearance .
The results also indicated that all fluoride concentrations in Mosul
city drinking water were less than the optimum value which is (0.7)mg/l ,
according to EPA. This value was stabilized according to the mean value
of maximum daily temperature for the Mosul city (28.42) ○C over the last
(5) years. However, to avoid consumed excessive dosage of fluoride, the
fluoridation should not be practiced unless it is advised by the specialists
in the nutrition, public health and dentistry. The fluoride may be supplied
to the human by sources other than water, also there is a variety in the
amount of the fluoride consumed by different persons.

Sheet metal forming is defined as the ability of metal to deform
plastically (deformation by Stretching or drawing) or changing the shape
of the sheet into a new desirable shape with out necking or crack . To
control the operation of sheet metal forming with out failure. A diagram
is used in which the range accepted , failure and critical deformation
range are shown . This diagram is known as the Forming limit diagram. It
is considered as one of the important tool to determine the formability of
sheet metals. Every sheet metal has its own forming limit diagram which
determines its formability, strain limit and the forming regions. These
diagrams can be assessed using theoretical and experimental approaches,
In this paper, the FLD is determined using different yield criteria
Hill1948, Hosford1979 and modified Hosford 1985. It is shown that the
determination of forming limit curve using the modified Hosford 1985
criterion with the (M-K) analysis , gave the best results compared with
the other used criteria .Using this criterion gave the closest forming limit
curve to that obtained experimentally, but with different criterion index
for different alloy . The value of the index (a=6) gave the best results for
brass, while (a=8) gave the best results for aluminum alloy and mild steel.

The study focused on evaluating the Wady ‘Eqab wastewater effluent,
which is discharged directly in Tigris river. This effluent represents a
mixture of industrial and domestic wastewater, that collected the large
portion of the wastewater from industrial district at right bank of river and
some residential quarters.
According to Iraqi standard for conservation of water resources, The
suspended solid concentration for stream effluent increased by (122%)
and other impurities increase by (16%-29%), Where is according to
organic load, the stream effluent classified as weak, for its biological
oxygen demand (BOD5) is (56)mg/l as an average. As compared with
Municipal wastewater for last previous years, Wady ‘Eqab wastewater
impurities were with less concentration levels; These impurities increased by different percentage and some exceeds (34) times. However, The river
water is still clear and within the Iraqi standards for conservation of water
resources, for the region follow the stream discharge point.

The behaviors of structural waves (axial, shear and bending) are
studied in multi-material beams and single material plates using the
method of characteristics (MOC). The characteristics equations in one
dimensional problems are extended and derived to cover the two
dimensional problems and to make the method be applicable to study the
wave behavior in plates.
The results showed that the structural waves changed their forms
during their propagation in the multi-material beams and some reduction
is occurred in the natural frequency of the beam. The propagation of
structural waves in plates showed same behavior as in beams, so the
propagation in two directions can be separated and each direction can be
considered individually as one dimensional problem to simplify the
characteristics equations and saving the computing time and solution
techniques.

The Dynamic Regression model (DR) was used for forecasting the
discharge of Adhaim and Greater Zab rivers with considering the effect
of rainfall on the discharges.
The auto correlation function (ACF) was used to determine the
stationary level of the time series, also the partial auto correlation
function (PACF) was used to identify a suitable Auto Regression
Integrated Moving Average (ARIMA) model for time series of rainfall
and discharges for both rivers and the factors of the transfer function
models (TF) were determined. The model passed the tests successfully
and the dynamic regression model for both rivers became suitable for
forecasting the discharges depending upon the historical data of the
rainfall and the discharges.

The research focuses on the behavior of laboratory bench-scale
filters that receive low-turbidity raw water. The filters have different
configuration in terms of materials type, materials size and thickness.
These filters operate under in-line and direct mode of filtration with
different doses of alum and coagulant aid.
A total of 200 filter runs were conducted. Statistical methods had
been used in the determination of best configurations of tried filters.
Analysis of variance (ANOVA) and Duncan multiple range test had been
employed for this purpose.
The results showed the superiority of filters operating under direct
filtration mode compared to those of in-line filtration mode. It was
thought that flocculation played a role in this result. Fine sand media of
0.56 mm E.S appeared to surpass the coarse media due to more trapping
of impurities at pore spaces. The effect of coagulant aid addition was
detected to act positively only with capping media filters, where an
improvement in performance did occur. However, such improvement was
low and did not justify importation of anthracite coal and coagulant aids
and add an economic burden.

In this paper a hydraulic study on free flow under sluice gate have
been carried out in a rectangular flume using six gate cases (vertical gate
and inclined with angles (30,45,60)o with a horizon in flow direction and
(30&45)o opposite it. Four gate opening (2,3,4,4.5) cm and five different
upstream heads (18.9,21,24,26,28.9) cm, were used. The coefficient of
discharge (Cd) have been evaluated and shown that the average value of
this coefficient increases from (0.645) for vertical gate to (0.832) for
inclined gate (60)o with flow direction, while it decreases to (0.576) for
inclined gate (45)o opposite flow direction .
A general equation of free flow under vertical and inclined gates,
with any angle and with flow or opposite it, was contrived with error
percentage not exceed (12.32)%.

The urban environment represents an expression of the
temporal status of its society . Any alterations caused by the
development of this society will be followed by changes in the built
environment and these will affect the spatial organisation attributes of
this environment .
This research explains the similarities and dissimilarities of
spatial organisation attributes for both traditional and contemporary
urban areas . Two temporally different districts in Mosul are selected
as a case study and they are analysed using the space syntax
methodology .
The research is ended with a number of findings which
explain the attributes of each district , the traditional one has its
efficient accessability with high control on any strange traffic while
the influence of the designer is obvious in the organization of spaces
in the contemporary district.

Within the discipline of domestic Architecture, the
relationship between areal determinations and design attributes ofthe traditional residential units represents a variable that lacks
adequate research endeavors.
Accordingly, this study hypothesized the existence of a
relationship between areal determinations and design attributes, in
traditional residential units in Mosul city.
The first stage of solution was to select a purposive sample of
50 units, measuring its variables, and finally a statistical analysis
was made.
A number of findings were obtained, explaining the relations
between the design attributes of the residential units and their areal
components.