AL-Rafidain Engineering Journal (AREJ)

The present paper describes the results of testing folded and flat ferrocement panels
reinforced with different number of wire mesh layers. The main objective of these
experimental tests is to study the effect of using different numbers of wire mesh layers on the
flexural strength of folded and flat ferrocement panels and to compare the effect of varying
the number of wire mesh layers on the ductility and the ultimate strength of these types of
ferrocement structure. Seven ferrocement elements were constructed and tested each having
(600x380mm) horizontal projection and 20mm thick, consisting of four flat panels and three
folded panels. The used number of wire mesh layers is one, two and three layers. The
experimental results show that flexural strength of the folded panels increased by 37% and
90% for panels having 2 and 3 wire mesh layers respectively, compared with that having
single layer, while for flat panel the increase in flexural strength compared with panel of plan
mortar is 4.5%, 65% and 68% for panels having 1, 2 and 3 wire mesh layers respectively. The
strength capacity of the folded panels, having the particular geometry used in the present
study, is in the order of 3.5 to 5 times that of the corresponding flat panels having the same
number of wire mesh layers. Both types are also analyzed using finite element method to
check the flexural stresses in these panels under self weight and cracking load.

A higher-order conical frustum shell strip for analysis of free vibration of curved box
girder bridges is developed, the auxiliary nodal line technique is used in the formation, the
application of the motion equation by form the matrices of the stiffness and that of the consist
mass of the strip and which has been mathematically derived by solving sixth and third order
equations for bending and in plane actions respectively. Guyan reduction technique have been
applied for each stiffness and the mass matrices of bridge. The strip which implies
minimizing the degrees of freedom of the auxiliary nodal line of the Higher Order Finite Strip
in order to reduce the size of the matrix from (15x15) to (8 x 8).
The study has come out with very good results compared to the previous studies in terms
of the natural frequencies for the first harmonic number of the box girder bridge section
which is composed of two box cells with inclined webs. The ratio of difference between the
present and previous studies have reached (6.73%) , while the natural frequencies for the
seconed harmonic number of the same box section the ratio is about equal (3.765%) .

A study on the behavior of reinforced high-strength concrete corbels is carried out
using nonlinear finite element analysis and a simplified softened strut-and-tie model. In the
numerical analysis, eight-node isoparametric plane stress elements are employed to model the
concrete material. An elastic-strain hardening plasticity approach combined with cracking
damage is used in modeling the concrete behavior. The reinforcing bars are treated as
embedded elements and are considered as elastic-perfectly plastic material. In the analytical
method, the analysis is based on truss analogy following the provisions of Appendix A of the
ACI 318-05 Code. Strength predictions of both methods correlate well with the 34 test results
of corbels available from the literature. It was concluded that the adopted finite element
model is a powerful tool for the analysis of such disturbed region. Also the simple truss
model used proved to be a suitable design tool for these members. The finite element method
can be used in conjunction with the truss analogy for optimum design.

The current research includes practical results of study and investigated the subject of
strengthening the shear strength through uniaxial confinement (one direction) using GFRP
Sheets. This study was carried out by casting eight specimens (the push-off specimens group)
which was divided in to four groups, the first non confined, being the reference group, the
remaining groups consisted of two specimens each with only one variable being the degree of
strengthening that is the numbers of confinement layers. The second, third, and fourth group
were confined with one, tow, and three layers respectively. All specimens were tested through
the application of a vertical load up to failure. The result indicated that there is a clear
indication of shear strength increase amounting to 33% relative to the reference specimens
(non confined), also there was a noticeable increase in the absorption capacity as a function of
the number of confinement layers.

DC Drives have been used and still being used in many industrial applications as
adjustable speed drives. Among these applications are robotics, mill, steel, cement…etc, [1]
industries. The dual converters are the most common power electronics equipments that are
used in driving DC motors. Each converter drives the motor in two different quadrants in the
torque-speed diagram, thus the drive system becomes a four-quadrant. Computer Simulation
results has been obtained for the steady state condition. The results are in the form of motor
and converters currents and voltages for different trigger angles. In order to validate the
simulated results, practical results have been obtained for the same triggering angles. For
dynamic conditions such as starting condition have been obtained practically and compared
with the simulated results, be sides that studying some abnormal conditions such as fault
condition with in the motor or in the dual converter.

I n this paper, an experimental investigation was conducted to explore the mechanical
properties of air entrained steel fibers reinforced concrete (AESFC). The residual mechanical
properties measured include compressive and splitting tensile strengths, modulus of elasticity
and (stress – strain) curves. Air-entrained concretes (AECs) were prepared with different
steel fibers content (0, 0.4, 0.8, and 1.2) % added to enhance the strength of concrete. After
exposure to high temperature included (200, 400, 600) ????C, the residual mechanical properties
of AESFC were investigated and compared with normal concrete. Test results showed
reduction in properties by different ratio for all types of concrete after exposure to elevated
temperature, the tensile strength and elastic modulus deteriorated with temperature more than
the compressive strength. Using steel fibers seems effective in minimizing the degradation of
strength for the concrete. Results showed also that the decrease in compressive strength after
exposure to high temperature could be reduced by increasing volume of samples. Heating
accompanied with weight losses and color changes became clearer at (400 – 600) ????C
exposure.

Many local field studies on sprinkler spray losses in Iraq have been conducted, the first was in
1980 and the latest is in 2008. Many equations to estimate these losses have been proposed.
But, most of these studies depended on narrow ranges in the values of the parameters and
variables involved. Therefore, there may be great risk in applying these equations in the
design and management of sprinkler irrigation systems. Add to that, the problem of
unavailability of data for some of the variables involved which makes the use of these
equations impossible. Thus, this study presented a group of 14 prediction equations for the
sprinkler spray losses, so that it becomes possible to estimate these losses if one or more of
the following main variables is available: air temperature, wind speed, relative humidity,
nozzle size, and operating pressure head. The derivation of the proposed equations depends
on all available local field data, thus making these equations more accurate and general.

The present paper includes analytical investigation of the validity of total resistance
heat dissipation model using variable heat transfer coefficient for annular fins constant
thickness. The model is given as:
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Furthermore, a finite difference method using SOR technique is devised to serve the
two purposes of verifying the two dimensional heat transfer model and to cover a wide
range of fin parameters and heat transfer coefficient models. The results were in agreement
and proved the validity of the suggestion model under the both the constant and variable
heat transfer coefficient assumptions.

A laboratory study was conducted on stepped and unstepped weirs in order to find their
efficiency of dissipating flow energy. Thirty six weirs were constructed and tested to compare
between stepped and unstepped weirs in flow energy dissipation, twenty seven of them were
stepped while the rest were unstepped. Three heights of stepped weirs (P=36,45,54)cm were
used with different numbers of steps (n=9,12,15) , and three downstream slopes of stepped
face (h/l=1/2,1/3,1/4) were tested, while for unstepped weirs one height of weir (P=54)cm and
three downstream slops (????=26.6o,18.4o,14o) were tested. The results showed that increasing
height of weir and decreasing both number of steps and downstream slops stepped face of the
weir will cause an increase of the ratio of flow energy dissipation, and the stepped weirs are
more efficient in flow energy dissipation compared with unstepped weirs. The percentage of
flow energy dissipation (E%) is increased by increasing the ratio of height of weir to critical
water depth (P/dc), the ratio of length of the step to critical water depth (l/dc) and the ratio of
height of step to critical water depth (h/dc) while it decreases by increasing the discharge (Q).
Imperical relationships between the ratio of flow energy dissipation and factors affecting it
were obtained in stepped weirs.

Natural convection in a saturated porous medium bounded by two horizontal eccentric
ducts is studied numerically by solving the governing Darcy-Boussinsq equations using finite
differences on very fine grid. This paper reports the effect of the position of a cooled square
body with respect to the centre of the square cavity vertically and horizontally. The numerical
results of heat transfer are presented for modified Rayleigh number Ra* (based on width of
cavity) in the range (50 to 400) and for different size of the body with respect to the width of
the cavity (0.25x0.25,0.3x0.3,0.5x0.5) and six positions of the body respect to the center of
cavity. The results are represented by streamlines and isotherms to show the behavior of the
flow and temperatures distribution. Also some graphics had been obtained which represent
the relationship between Nusselt and Rayleigh numbers with eccentricity. (Key words: natural
convection, porous medium, cavity)

A lthough many studies have tried to reduce differences between conceptual models of
thinking processes, through the description of the operational performance of any intellectual
task includes problem solving, however, because of the design specificity in this regard, and
diversity of its motion, there were always, many of obstacles that stand in the way of
developing a model describes the operations of reasoning achievement during different
architectural design phases. The need for explicit language of designer thinking, and
architects performance or how they underlined such aspects, was incentive concern for many
contemporary studies, which tried to cover this area in one way or another. This research tries
to investigated designer logical behavior during a design process, through the review of
inference acts, during conceptual stage of that process, also it tries to investigate the nature of
the mobility of this behavior across time of the task.

This paper presents hardware implementation of least mean square (LMS) adaptive
filter based Adaptive Noise Canceller (ANC) structure on FPGA using VHDL hardware
description language. First, the adaptive parameters are obtained by simulating ANC on
MATLAB. Second, the data, processed by FPGA, such as step size, input and output signals,
desired signal, and coefficients of ANC, are exactly expressed into fixed-point data
representation. Finally, the functions of FPGA-based system structure for such LMS
algorithm in time sequence are synthesized, simulated, and implemented on Xilinx
XC3S500E FPGA using Xilinx ISE 9.2i developing tool. The research results show that it is
feasible to implement, on chip train, and use adaptive LMS filter based ANC in a single
FPGA chip.

Spatial organization is the operative mean through which built environment expresses the
Purposes of its creation.
Due to its ability to provide basic requisites of movement, encounter and avoidance
patterns, Modern Studies assume Spatial Organization as the main generator of Social life.
Syntactical relations of Spatial and Visual organization for Mosul University Campus
components, represents phenomena that lacks adequate research endeavors, despite its
importance as a social organization phase, and a human mode of reaction. Accordingly, this
paper aims to explain these relations.
Using Space Syntax methodology, a number of findings were obtained, explaining Spatial
and Visual properties of Mosul University Campus components.

This paper investigates the effect of quantization gain factors, at the input side, and the
scaling gain, at the output side, of a fuzzy controller. A fuzzy control system is designed with
two main parts: a basic fuzzy controller (BFC) which produces the output control signal and
supervisor fuzzy controllers (SFCs) to continuously adjust, on-line, the I/O scaling or gain
factors of the (BFC) in order to improve its performance against different dynamic operating
conditions. The designed self tuning controller is used to position control of a DC motor with
un known parameters according to the feed back inputs, a tracking error (e) and change of
error (????e), based on the proposed fuzzy rules. The system implementation and tests are
carried out using LabVIEW software ( V8.2 ) with a data acquisition card type (NI PCI-
6251) from National Semiconductors to achieve real time measurements.

I s lamic architecture is considered to be a unique example that reflects the impact of
structural formation systems in establishing its form; the structural relations represent the
most important items and bases of architectural structures, especially at the abstract level. The
structural relations form the basic foundation which represent the most important aspect in
producing the formal structure of any building thus they are considered to be the most
important method in describing the physical reality of architectural production . Stemming
from the above fact, the study focuses on the structural relations that form the plans. The
problem of the study is that structural relations which form the plans of Khans buildings in
Islamic architecture are not clear. The aim of the present study is to clarify the specialty of
Muslim architect intellectuality in the formation of a particular mechanism or method to form
and design studied plans with specific functions like khans. To achieve the aim of the study a
theoretical framework of structural relations is built depending on modern studies on
formation of those relations on the bases of the statistical analytical method. The results
arrived at show that the structural relations which form and construct the plans of Khans
buildings are characterized by uniqueness as a distinguishing character of Islamic architecture
some of these types of building are the khans, though they differ in their architectural design,
their date and ever their geographical location. This in turn gives an indication and proof of
the Muslim architect creative role in determine the distinguished identity of his architecture
with the incentive of Islamic cultural intellect held by that architect all over the places of his
civilization whenever and wherever he exists.