Al-Qadisiyah Journal for Engineering Sciences

The present study includes an experimental investigation of the behavior of
simply supported lightweight aggregate concrete (LWAC) and normal weight concrete
(NWC) square slabs reinforced by different ratios of carbon fiber reinforced polymer
(CFRP) and/or steel bars reinforcement. The experimental program consists of testing
nine two-way reinforced concrete square slab models under uniformly distributed load
(UDL). They were of the same overall dimensions, (1050×1050×80) mm. The main
variables considered in the experimental study are: type of concrete; LWAC or NWC, type
of reinforcement; steel, CFRP and hybrid (steel and CFRP) bars with different ratios and
arrangements, the behavior of slabs with bottom and top CFRP bars reinforcement and
the efficiency of using CFRP bars for strengthening slabs in two directions by using near
surface mounted (NSM) technique. In this study, a waste of clay bricks was used as a
coarse lightweight aggregate (CLWA) to produce structural lightweight aggregate concrete
(SLWAC).
It was found that LWAC slab model reinforced by CFRP bars has a lower total weight by
amount 20% in comparison with NWC slab model reinforced by CFRP bars with rather a
small reduction in slab ultimate load capacity by amount not more than 6.5%. However, it
was found that the CFRP reinforced LWAC slab model can achieve ultimate load capacity
higher than equivalent steel reinforced LWAC slab model by about 34.62%. NSM
technique by CFRP bars in two directions of LWAC slab is very effective and nearly
provided the same efficiency of equivalent internal reinforcement.

: This research proposed a model describing the relationship between ultrasonic
pulse velocity (UPV) and the compressive strength test of concrete containing PET
(Polyethylene terephthalate). This was achieved by measuring ultrasonic pulse velocity
(UPV) on this type of concrete and comparing the result of compressive strength tests to
clarify the accuracy of the ultrasonic test equation for this type of concrete. Waste bottles
of water was used in this study by cutting them into laminar form of fibers with zigzag
edges in different length (1,2,3) cm for each volume fraction of PET (1%,2% and 3%) by
cement weight with fixed width (0.5) cm. Then, they were incorporated with the concrete. It
was noticed from the laboratory tests results that the relationship UPV - strength are
related together in the volume fraction of 1% for the length 3cm and the correlation factor
(R) is equal to 0.94. This indicates a very good exponential relationship between UPV and
compressive strength. Also, the results are compared and discussed with another
proposed formula that found in literature.

An integrated drive arrangement for a wastewater pumping system was
designed and modeled to evaluate the energy saving gained from matching motors with
Variable Frequency Drive (VFD) and Programmable Logic Controller (PLC). The proposed
arrangement utilizes the affinity laws of centrifugal pumps to predict the performance of a
pump under different rotational speed conditions. The specific energy (Es) is used as a
measure of the cost effectiveness of the proposed pumping system.
Results have shown that a reduction of 10% in pump speed can save 30% in energy of
maximum speed. The energy saving potential is carried out for a real-life case study, and
a conclusion to replace on-off controllers currently used for most wastewater pumping
systems is necessary. The total energy saving account for more than 50% when
integrated drive system was applied for a combined sewer pump station.

Aluminum alloy (7075-T6) is widely used in various industries in parts of aircraft,
automobiles and other mechanical applications. It is known that the process of the shot
peening leads to an increase in the value of residual stresses, which prolong the fatigue
life. However, during surface peening of various metals, including aluminum alloy (7075-
T6) used in this work, these surfaces become rough where the places to concentrate the
stresses, which will fail when exposed to different dynamic stresses. This paper presents
an study on the effect of polishing (the roughness surface induced from shot peening
process) on endurance limit and residual stresses result by shot peening. In this paper
was used three values of surface roughness (1.5, 3, and 5) μm. The obtained results show
that the maximum increasing in endurance limit was (53%) at low roughness compared
with as received and increasing value roughly to (27%) compared with alloy after shot
peening. . The residual stresses gradually increased (-222.735, -229.602, -250.900) Mpa
when the roughness surfaces decreased (5, 3, 1.5) μm respectively.

Modeling driver behavior is the corner stone for any traffic simulation model.
Driving behavior is a complex task to mimic the reality by simulation model. This study has
focused on collecting field data from several rural road sites. These data include lane
utilization, lane changing and headway. Then, a simulation model has been developed for
representing the driver behavior at rural roads. Car-following model developed in this
study is safety one. Then, lane changing hybrid model has been developed according to
the suggested assumptions by previous studies and collected field data to match the real
behavior. Gap acceptance model has been adopted from previous studies which show
good consistency with real driver behavior through comparing with other characteristics
such as lane changing and lane utilization. The developed model has been calibrated with
field data and showed encouraging results

This article dealt with an important heat transfer field, which is passive heat
transfer technique represented by corrugated tube. The study conducted numerically by
ANSYS Fluent 14. The motivation behind the current study was to clarify the
characteristics and merits of such tube geometry in terms of heat transfer and pressure
drop. The obtained results reported under constant heat flux, temperature-dependent
thermo-physical properties and Reynolds number range of 300-1500. Results show good
heat transfer enhancement of 6.15-33.24% in spite of an increase in friction factor of 1.80-
2.93 times the smooth values. The corrugated tube with φ =4.76×10-2
has the top thermal
1.16-1.25 for all Reynolds number. The most important finding is that the gained heat
transfer is much more than the increase in pressure loss until a certain threshold of
Reynolds number about 900, later, the pressure loss increase and dominates over the
heat gained. The effect of Prandtl number on the heat transfer for three types of fluids
produced too. A criterion correlation equation of Nusselt number developed to describe
the cases of four starts spirally corrugated tubes by deviation ±3% compared with the
simulation results.

The samples of AISI 1018 Low carbon steel were heated to austenite zone then
cooled in different mediums with different cooling rates. Mechanical tests show increase in
hardness, yield strength, tensile strength, modulus of elasticity, and yield/tensile ratio as
cooling rate is increase. Ductility has inverse proportionality to cooling rate. The resulting
microstructures show decreasing in grains sizes accompanying to cooling rate increase.
The relations between mechanical properties and grains size are opposites of relations
between mechanical properties with cooling rates. Hardness, yield strength, tensile
strength, modulus of elasticity, and yield/tensile ratio increase as grains size decreases,
while ductility decreases

: Construction and demolition of buildings and structures are producing excess or
waste material which is including concrete, brick, steel, etc. Conservation and reuse of
resources is a necessity in achieving sustainability across the globe, crushed brick could
be safely added to crush rock blends in pavement sub-base applications with percent up
to 25%. The experimental work was consisted of two groups of samples depending on
percent volume of each material, each group samples have 6 different layering blends
patterns prepared by spreading the pure materials in layers (segregated form) of Crushed
Bricks Sand (CBS) and Natural Aggregate (NA), in addition to the two control samples and
then experimentally tested to compare with the requirements of Iraqi specification for
roads and bridges. The experimental work was consisted of Atterberg limits, sieve
analysis, moisture-density relationship and California Bearing Ratio (CBR) tests. The
results show that using of the crushed bricks as sand with natural aggregate as unbound
subbase in segregated form is feasible and agreed with the Iraqi specification
requirements because the CBR of CBS was improved when blended with the NA at all the
patterns, the best pattern is that which containing three layers NA and two CBS (60% NA
and 40% CBS by volume) and the NA was at the top, then CBS in alternated sequence
that improves the CBR value to 1.6 times compared with NA control or 8 times of CBS
control because the sporadic distribution reduces the effect of the low bearing material, in
another words; collect the layers of the same material doesn\'t give best improvemen