Journal of Engineering

The present work aimed to study the efficiency of nanofiltration (NF) and reverse
osmosis (RO) process for water recovery from electroplating wastewater and study the factors
affecting the performance of two membrane processes. Nanofiltration and reverse osmosis
membranes are made from polyamide as spiral wound module. The inorganic materials ZnCl2,
CuCl2.2H2O, NiCl2.6H2O and CrCl3.6H2O were used as feed solutions. The operating parameters
studied were: operating time, feed concentrations for heavy metal ions, operating pressure, feed
flow rate, feed temperature and feed pH. The experimental results showed, the permeate
concentration increased and water flux decreased with increase in time from 0 to 70 min. The
permeate concentrations increased and flux decreased with increase in feed concentrations from
10 to 300 mg/l. Raising of pressure from 1 to 4 bar, permeate concentration decreased for RO,
for NF decreased and then increased at high pressure and increase the flux. The rises of flow rate
from 20 to 50 l/h decreased permeate concentration and the flux increase. The rises of
temperature from 26 to 40 °C, increased permeate concentration and increased the flux. The rise
in pH from 4 to 7, decreased the flux as the pH goes from acidic side towards alkaline. The
polyamide nanofiltration membrane had allowed permeation of chromium and copper ions to
lower than permissible limits. Nanofiltration membrane had allowed permeation of nickel and
zinc ions at low concentration of these ions. The polyamide RO membrane gave a high
efficiency for removal of chromium, copper, nickel and zinc and it had allowed permeation of
these ions to the lower than permissible limits. The rejection at first three minutes when the feed
concentration approximately was constant for chromium in NF and RO, was 99.7% and 99.93%,
for copper was 98.43% and 99.33%, for zinc was 97.96% and 99.49%, and for nickel was
97.18% and 99.49% respectively. The maximum recovery for chromium in NF and RO was
71.75% and 48.5%, for copper was 75.62% and 50.68%, for zinc was 80.87% and 54.56%, for
nickel was 60.06% and 46.18% respectively. For a mixture of synthetic electroplating
wastewater, nanofiltration and reverse osmosis membranes have a high rejection percentage for
heavy metal ions. It was obtained pure water and concentrations of less than allowable limits for
heavy metals in the case of the mixture.

The present paper addresses cultivation of Chlorella vulgaris microalgae using airlift
photobioreactor that sparged with 5% CO2/air. The experimental data were compared with that
obtained from bioreactor aerated with air and unsparged bioreactor. The results showed that the
concentration of biomass is 0.36 g l-1 in sparged bioreactor with CO2/air, while, the concentration of
biomass reached to 0.069 g l-1 in the unsparged bioreactor. They showed also that aerated bioreactor
with CO2/air gives more biomass production even the bioreactor was aerated with air. This study
proved that application of sparging system for cultivation of Chlorella vulgaris microalgae using
either CO2/air mixture or air has a significant growth rate, since the bioreactors become more
thermodynamically favorable and provide impetus for a higher level of production.

Low incoming discharge upstream of Samarra-Al Tharthar System leads to sediment
accumulation and forming islands, especially an island upstream of Al Tharthar Regulator. This
island and the sedimentation threaten the stability of the structure and reduce the efficiency of
the system. This study aims to hydraulically identify the sedimentation problem mentioned
above, to find solutions of how to control the sediment problems, and to develop the capacity of
the system for 500 years return period flood of 15060 m3/s. Surface Water Modeling System
(SMS10.1) with two dimensional depth average models (RMA-2) software were used to simulate
and analyze the system. The results of analysis showed that the maximum permissible discharge
through the system was 8250 m3/s where the discharge from Samarra Barrage was 2400 m3/s to
avoid flooding in Baghdad city. The water surface level could be lowered during constructing;
the new Al Tharthar Regulator expansion capacity of 7000 m3/s in the case of peak flood (15060
m3/s) to 68.51 m.a.m.s.l. upstream of Samarra Barrage by dredging the island and channel. On
the other hand, during constructing the guide bank, and dredging the island and channel, the
water surface elevation was 68.91 m.a.m.s.l. upstream of Samarra Barrage.

This work aimed to design, construct and operate a new laboratory scale water filtration
system. This system was used to examine the efficiency of two ceramic filter discs as a medium
for water filtration. These filters were made from two different ceramic mixtures of local red
clay, sawdust, and water. The filtration system was designed with two rotating interfered
modules of these filters. Rotating these modules generates shear force between water and the
surfaces of filter discs of the filtration modules that works to reduce thickness of layer of rejected
materials on the filters surfaces. Each module consists of seven filtration units and each unit
consists of two ceramic filter discs.
The average measured hydraulic conductivity of the first module was 13.7mm/day and that
for the second module was 50mm/day. Results showed that the water filtration system can be
operated continuously with a constant flow rate and the filtration process was controlled by a
skin thin layer of rejected materials. The ceramic water filters of both filtration modules have
high removal efficiency of total suspended solids up to 100% and of turbidity up to 99.94%.

A tungsten inert gas (TIG) welding is one of the most popular kinds of welding used to join
metals mainly for aluminum alloys. However, many challenges may be met with this kind of
joining process; these challenges arise from decay of mechanical properties of welded materials.
In the present study, an attempt was made to enhancing the mechanical properties of TIG weld
joint of 6061-T6 aluminum alloy by hardening the surfaces using shoot peening technique. To
optimize the shoot peening process three times of exposure (5, 10, and 15) min. was used. All
peened and unpeened, and welded and unwelded samples were characterized by metallographic
test to indicate the phase transformation and modification in microstructure occurring during
welding process. Tensile test and Vickers micro-hardness measurements were performed for all
samples to investigate the effect of shoot peening on mechanical properties of welded aluminum.
The results indicated a significant improvement in properties for peened welded and unwelded
samples compared with those unpeened one. Also, the results showed that the tensile and micro
hardness properties were increased with increasing the time of exposure to 15 min. due to
generation of compressive residual stresses at surface.

Unsaturated polyester was used as a matrix which was filled with different percentages of
cobalt ferrite using hand lay-up method. Cobalt ferrite was synthesized using solid state ceramic
method with reagent of CoO and Fe2O3. Mechanical properties such tensile strength, Young's
modulus and shore D hardness of the composite have been studied. All these properties have
increased by 10% with increasing cobalt ferrite contents. Also the thermal properties such
thermal conductivity and specific heat capacity are highly increased as the ferrite content
increased, while the thermal diffusivity increased by 22 %. On the other hand dielectric strength
of composite has been measured which increased by 50% by increasing the cobalt ferrite content.

In this investigation, Rayleigh–Ritz method is used to calculate the natural
frequencies of rectangular isotropic and laminated symmetric and anti-symmetric
cross and angle ply composite plate with general elastic supports along its edges. Each
of the admissible functions here is composed of a trigonometric function and an
arbitrary continuous function that is introduced to ensure the sufficient smoothness of
the so-called residual displacement function at the edges. Perhaps more importantly,
this study has developed a general approach for deriving a complete set of admissible
functions that can be applied to various boundary conditions. Several numerical
examples are studied to demonstrate the accuracy and convergence of the current
solution with considering some design parameters such as boundary conditions,
aspect ratio, lamination angle, thickness ratio, orthotropy ratio, also these results are
compared with other researchers and give a good agreement .

The aerodynamic characteristics of general three-dimensional rectangular wings are
considered using non-linear interaction between two-dimensional viscous-inviscid panel method
and vortex ring method. The potential flow of a two-dimensional airfoil by the pioneering Hess
& Smith method was used with viscous laminar, transition and turbulent boundary layer to solve
flow about complex configuration of airfoils including stalling effect. Viterna method was used
to extend the aerodynamic characteristics of the specified airfoil to high angles of attacks. A
modified vortex ring method was used to find the circulation values along span wise direction of
the wing and then interacted with sectional circulation obtained by Kutta-Joukowsky theorem
of the airfoil. The method is simple and based mainly on iterative procedure to find the wings
post stall aerodynamic results. Parametric investigation was considered to give the best
performance and results for the rectangular wings. Wing of NACA 0012 cross sectional airfoil
was studied and compared with published experimental data for different speeds and angle of
attacks. Pressure, skin friction, lift, drag, and pitching moment coefficients are presented and
compared good with experimental data. The present method shows simple, quick and accurate
results for rectangular wings of different cross-section airfoils.

Experimental measurements of viscosity and thermal conductivity of single layer of graphene
based DI-water nanofluid are performed as a function of concentrations (0.1-1wt%) and
temperatures between (5 to 35ºC). The result reveals that the thermal conductivity of GNPs
nanofluids was increased with increasing the nanoparticle weight fraction concentration and
temperature, while the maximum enhancement was about 22% for concentration of 1 wt.% at
35ºC. These experimental results were compared with some theoretical models and a good
agreement between Nan’s model and the experimental results was observed. The viscosity of the
graphene nanofluid displays Newtonian and Non-Newtonian behaviors with respect to
nanoparticles concentration and temperature, and about 111% enhancement was obtained
compared to the base fluid with GNPs weight fraction concentration of 1wt.% at 35ºC. Based on
the experimental data, correlations were developed for predicting thermophysical properties of
the GNPs based DI-water nanofluid.

This paper concerns with openness concept in contemporary learning environment, which
ranges from physical characters to its relation with learning efficiency and its output. Previous
literatures differ to clear the effect of openness on the engagement between learner within
themselves, and with this kind of spaces. Engagement means: active participation, the ability of
making dialogue, self-reflection and the ability to explore and communicate with them and
within learning space. Research roblem was: The lack of knowledge about the effect of Openness
on learner engagement with learning spaces. The two concepts were applied on three types of
learning spaces in the Department of the Architecture in the University of Technology, according
to their measurements. The research found that there are two types of engagment, positive and
negative, that effect of openness in learning space, as increasing of the openness in learning
space as more of the positive engagement of the learner, offset by a decrease in the negative
engagement which cause conditions of the boredom and loss of concentration and scattering the
learner mind - within this kind of space.