AL-Rafidain Engineering Journal (AREJ)

In this paper, an experimented study is presented which determines the memory
switching criterion for CdS/SiO/CdTe devices. The dc. characteristics obtained from
isolated devices on various glass substrates, but having the identical CdS and CdTe
semiconductors with different sandwiched SiO thicknesses reveal that the device
impedance at OFF state is almost determined by the tunnel oxide thickness. But the
forward and reverse threshold voltages are determined by the top contact area of the
device. Physical arguments are presented which adequately explain the experimental
results in this paper.

An attempt has been made to study the effect of moisture content variation on the strength characteristics of sandstone rock selected from east of Mosul city center. Both compressive and indirect tensile strengths of the rock were determined.The
obtained results indicated that the water has a considerable effects on both the
compressive and tensile strengths. Higher reduction in the compressive and tensile
strength were observed when the moisture content percent was between (0%-4%) and
(0%-8%) respectively.The results also indicated that the effect of moisture content on
tensile strength is greater than it's effect on compressive strength.

Worldwide interoperability for Microwave Access (WiMAX) is a broadband
wireless technology based on IEEE 802.16 standard . A WiMAX cell which is to be
considered in this study applies multicast mode of operation , the main limitation of
maximizing the capacity of the system is the signal to noise ratio (subscribers near the
base station apply 64 QAM and ¾ Reed Solomon code , while those which are near the
border of the cell applies PSK and ½ Reed Solomon code to compensate for the S/N
effect). Results indicate that better capacity is achieved by introducing Relay Stations
(RSs) and Adaptive Antenna System (AAS) to the cell with TDD mode of operation,
other factors like MAC and PHY layers overheads are studied and taken into account
in the calculation of the system capacity

The present study aims to obtain a relationship between the ultrasonic pulse velocity
which is one of nondestructive method of material testing and some of soil mechanical
and physical properties. In this study a relationship between the ultrasonic pulse
velocity through the soil samples and the unconfined compressive strength, dry density
and curing time was obtained in high plasticity clayey soil. The soil was compacted in
the cases of natural condition in standard and modified compaction effort, and in the
treated condition with ( 2,4,6,8 ) percent of lime, compacted with modified compaction
effort for three percent of water content(O.M.C, O.M.C ±4) these samples cured in
(25°)temperature in different curing time ( 0,2,10,20,42 ) day . After curing time end, all
samples tested in ultrasonic device and unconfined compressive strength device. The
results obtain from these tests, analyze and get a good relationship between the
ultrasonic pulse velocity and the unconfined compressive strength, dry density and
curing time with high correlation coefficient in all properties.

The precise position of the mobile station is critical for the ever increasing number of
applications based on location . In this paper a new approach for mobile positioning in
WCDMA (Wideband Code Division Multiple Access ) cellular network is proposed .
Radio Received Signal Strength Indication (RSSI) can be measured from a number of
nearby base stations . Three proposed approaches (3-BS's , 5-BS's and 7-BS's) are
simulated using three propagation models and the rmserror is calculated for each model.
As a simulation study case, the University of Mosul area is choosed to find the position
of a mobile user in the university campus .

An evaluation of the efficiency of conventional clariflocculator units with tube settlers
has been done in this study within the compact units in Mosul Unified Water Project. Results
of bimonthly samples were analyzed before and after treatment in the conventional project
with their correspondences in tube settlers within the compact units during period of January
2003 to June 2004 in order to investigate the expected water quality variety in Tigris river.
The results have shown that tube settlers are more efficient than conventional clariflocculator
units in removing turbidity and phytoplankton alga at a low turbidity level less than (30
NTU) and number of phytoplankton alga between (45–59) cell/ml. ????75%) of the residual
turbidity and phytoplankton alga after treatment was the best in tube settlers units. Results
also showed that conventional clariflocculator units are more efficient than tube settlers at the
water turbidity more than(30 NTU) and number of phytoplankton alga between (63–75)
cell/ml. (25%) of the total residual turbidity and phytoplankton alga after treatment was the
best in the conventional clariflocculator units.

Thermal insulation is the most effective energy efficient technique of energy
conservation available today. The main goal of energy an conscious designer is to
condition the interior environment to support a level of climate comfort acceptable to
users. From the past 20 years data it is concluded that temperature is at the increase
and thus thermal insulation is an immediate need to be considered. Environmental
problems have recently expanded due to industrial pollution and manmade products
that are found in solid wastes. One of these products are the Aluminum cans. Since the
recycling rate of these cans is decreasing. It is therefore the main goal of this study is to
evaluate the thermal insulation of these cans through models in insulating reinforced
concrete roofs and ceiling and comparing the insulation with that of Thermo-stone
blocks and Polystyrene boards which are commonly used in Iraq. Results indicated that
Aluminum cans are considered as a good insulator and can withstand a considerable
live and dead loads beside it’s low construction cost and low weight. Finally the use of
Aluminum cans in the thermal insulation will contribute in solving a part of the global
environmental problems.

Dairy liquid wastes contributes considerably in the pollution of the Tigris within
Mosul city particularly when suspended solids and oil pollution are concerned. Dissolved
air flotation( DAF) is introduced to tackle the discharges arise from this industry. A pilot
plant is constructed for this purpose. The pilot plant is subjected to variety of operating
conditions of detention time ( 6-24 minutes), recycle ratio (25-100 %), pressure(40-70 psi)
and air /solids ( A/S) ratio. The results revealed that the optimum values for detention
time, recycle ratio, and pressure were 18 minutes, 100% and 60 psi respectively. A
statistical treatment for the obtained results to relate all the studied factors is made in
order to establish the best relation that gives the best results. The percent removal of
suspended solids in the dairy discharges amounted to 80 % while that of oil amounted to
86%. This highly indicates the importance of introducing this physical unit among
conventional wastewater treatment units. It is concluded that DAF has many merits
represented by ease of operation, considerable reduction of pollutants which may be
reflected on subsequent units. Due to short detention time, this unit becomes small and
adds to the economy of the treatment.

One of the main causes of the earth dam failure is the seepage. This seepage can
cause weakening in the earth dam structure, followed by a sudden failure due to piping
or sloughing. For this purpose a finite element method through a computer program,
named SEEP2D, was used to determine the free surface seepage line, the quantity of
seepage through the dam, the pore water pressure distribution, the total head
measurements and the effect of anisotropy of the core materials of Duhok zoned earth
dam. First, the accuracy of the program was tested via the data of experimental dam
and the results showed an acceptable accuracy of the program. The effect of the ratio of
the permeability in the horizontal direction to that in the vertical direction (Kx/Ky) on
seepage was tested and results indicated an increase in seepage quantity as this ratio
increased. The stability of Duhok zoned earth dam was analyzed using a slope stability
computer program, named STABIL2.3. The program is verified through a dam
example of known factor of safety (solved by hand calculations). The results of the
verification indicated a good accuracy of the program. The slope stability analysis
results showed that the factor of safety decreases with the increase of Kx/Ky ratio. The
analysis of the results of this study showed that Duhok zoned earth dam is safe against
the danger of piping and slope sloughing under the present operation levels. Also, the
present study showed that the field piezometers readings of the dam are not accurate.

Previous studies have paid special attention to sculptural architecture because it
concerns about architectural composition, this paid attention is also likely to be due to
the fact that sculptural architecture has been a reaction to the principles and practices
of Modernism, as a result of modern practical developments in the field of construction
and as an aim in itself. This paper focuses on the discipline of sculptural architecture
seeking its identification and subsequently the establishment of its theoretical
framework based on previous research work. The paper shows that aspects of the
established theoretical framework can be clearly related to the various phases through
which the construction of a given building traverses, ranging from the initial phase of
motivation and concept design by the innovating architect to process of building
comprehension by recipient. The developed theoretical framework is then verified by
addressing Zaha Hadid’s pioneering work in this field, which is used here as case study.
The application of the theoretical framework has revealed a series of patterns in
Hadid’s work which may be attributed to her own architectural style. Similar results to
those obtained from the theoretical framework have also been made by other observers,
all of which point to the special paid attention by Hadid to modern construction
methods which she used symbolically and practically confirming her liberal
architectural style. The revelations demonstrate the validity of the assumptions made in
the development of the theoretical framework. Finally, this paper lays down a set of
guidelines for other architects who wish to apply Hadid’s approach in sculptural
architecture

This paper included an analytical study of a two dimensional (radial and transverse)
heat flow through annular fin variable thickness analytically depending on the group of
resistances by derivating the major equations of conduction and convection. The total
resistance equation of fin is derived to be general and simple model to calculate the heat
flow and to study the effect of fin parameters on it.
A numerical solution is added to prove the validity of the analytical solution by
using a grid generation transformation-algebraic method to regulating the irregular mesh on the fin surface.
Finally, the results show a good agreement between the two solutions using a wide range of fin parameters and this study is supposed to facilitate the designing of fin to the designer.

Truth is considered as an important concept in the modern architectural discourse
as it appeared explicitly within the theoretical statements and the practices of Modern
Movement. This research explores the concept of (Truth) in Modern Architecture to
clarify the items on which it is based and how it is produced in architectural artifacts.
However, this study concludes that (Truth) is a relative concept and it is based on two
types of items (conceptual and formal). These items and their related mechanisms are
explored empirically in selected works from Modern Architecture. It is concluded that
those items and mechanisms were varied regarding the clarity of occurrence and the
mechanisms used to imply the concept of (Truth) the selected works

Post occupated buildings have formed a subject examined by several architectural
studies and arose in their concluion the importance of suitable designing concepts that
promote the efficiency of its use arose these ideas into light was greatly envisaged in the
university libraries’ buildings in general and their reading spaces in particular, which
dominate real interaction among their designing characteristics and users’ preferences.The
research discusses the significance of what have been mentioned above and the reality of
knowledge related to it in the architectural reality to extract the special problem related to the
designing factors that are invested by designers in reading spaces which have an influence on
increasing their use efficiency.
Evaluation of several previous studies has led to identifying knowledge deficiency and
thus the research problem was represented by unclear theoretical knowledge which
determines and describes the set of the affecting designing factors in the usage efficiency and
determining its aim by revealing it. As to its methodology; it was represented by building up
a theoretical framework included two major aspects one of which discusses the designing
factors regarding the reading space; whereas the second includes the variables regarding the
usage efficiency. Then the theoretical framework was applied in the field aspect on selected
models from the libraries of the university of Mosul and determining the research population
among users.
Conclusions have shown an evident variation between the effect of the designing factors on
the use efficiency such that enable the designer investing, activating and determining the
priorities of future designing treatments.

This research tries to explain the effect of Ottoman mosques architecture on Mosul's
mosques architecture which had been erected or restored during the Ottomans era .
Some arguments and claims supposed that a direct effect emerged within this case
.while the finding of this paper based on the analysis of a purposive sample of the study
population indicates that this effect is too limited and the domestic identity of Mosul
mosques architecture during this era still keeping its own character .

The optimal hydrothermal scheduling is the distribution of load among the generating stations.
The objective function for the problem is to minimize total generating cost considering the
electrical and hydrological constraints. This problem is usually solved in two stages. The first is
to find the hydropower generation share, then to find the thermal generation share. This
research concerns the first stage. This work uses the Artificial Neural Network (ANN) to find
the optimal scheduling of the monthly water discharge over the year. The main power station of
Mosul dam is considered as an application example for this study. Six input variables are
chosen to be the input to the ANN. They are monthly inflow water, monthly demand water,
number of the month in a year, expected next year water inflow, available stored water (water
from the past year). The ANN is trained and tested by the available water flow data over the
past 65 years (1931- 1995). It is found that this technique enables the utilization of whole inflow
water for most of the years (within considered constraints) in spite of the great fluctuation of
inflow water for these years. Besides, this technique takes into account the status of the water
for last year and next year in addition to the year under study. This means that the water
distribution improves the utilization of available water over three years

This research deals with making a mathematical model for the design of a dual system
for hot water production for industrial purposes as well as cooling using an ejector at a
determined operating conditions, by utilizing dissipated thermal energy from a steam boiler
and for a cooling capacity of (15) KW. For the system simulation, mathematical relations
were presented for each component which were then combined together and programmed
using (matlab) version 6.5 to optimize the system performance and design the components at
this situation, using refrigerant (R-123) as the working fluid because of it's good
characteristics and relatively high efficiency after a comparison study with other suitable
refrigerants to be used for this system.
Satisfactory results were obtained having good agreement with previous researches and
a COP value of (0.667). The results show a suitable size of the designed system such that it
can be used in a wide range of cooling and hot water production purposes. Also, the effect of
operating conditions variation on the quantity and temperature of hot water and system
performance were studied.