Iraqi journal of mechanical and material engineering

An experimental investigation on solar chimney used for heating under climate of Iraq
is carried out. Experiments were conducted on the chimney installed on vertical wall with
absorber plate placed at the front side of the air gap. The solar chimney attached to room of
dimensions (2.5×1.29×1.07) m. The chimney is studied to measure the effect of the air gap
width with constant height of (1.07 m). Three widths are tested, namely, 0.2 m, 0.3 m and
0.4 m. The experimental results showed that the solar chimney can achieve about (13 °C)
difference in temperature between indoor and outdoor as well as it gives acceptable
difference in partial cloudy days. The results also indicated that the best performance of
solar chimney is with 0.3m air gap width.

This work presents design, instrumented and test of a parabolic trough solar collector
under Baghdad climate conditions (of latitude 33.33o N, of longitude 44.4o
E). The parabolic
trough solar collector consists of: a mirror matrix or tapes which work as reflective surface
of (2m *1m), absorber copper tube (receiver), two axis tracking system. Water is used as a
heat transfer medium. The setup is tested within clear days from June, to September 2017.
The collector heat gain, efficacy and temperature of absorber were presented for absorber
five different circulating mass flow rates of (0.15, 0.2, 0.3, 0.4, 0.5) 1pm. The results show
that the maximum thermal efficiency of the parabolic trough solar collector is 80.26%. The
maximum outlet temperature of the absorber tube reaches 81 oC at the noon when water
flows at (0.15) 1pm. The maximum obtained heat gain is (1619W) for (0.5) 1pm flow rate of
water

This research deals with the evaluation of buckling behavior for 6061-T4 aluminum
alloy under increasing compressive dynamic loads. Two types of columns, long, and the
intermediate columns were used. The number of specimens used in the dynamic axial
compression test were 9 samples .(1%) of the length column is the allowable lateral
deflection. For the purpose of calculating the initial deflection, the digital dial gauge was
used and the instrument was set at a distance of (0.7) of length from the fixed condition for
the column. A control system is designed to evaluate the critical buckling and to prevent
sample failure. The control system consists of a measuring circuit (transmitter circuit) with a
flex sensor installed at 0.7 of the total column length of the column's fixed condition. In
addition, the system contains a shutdown circuit (receiver circuit) to switch off the machine
at critical load with a mobile phone for the purpose of displaying deflection data. The
connection between the transmitter circuit and the receiver wirelessly through the RF sensor
and between the transmitter circuit and mobile phone also wirelessly via Bluetooth. The
results obtained were experimentally compared with the Perry-Robertson formula. It was
found that the Perry-Robertson formula was a good agreement with the experimental results
with a safety factor of (1.2)

Computational Fluid Dynamics (CFD) of indoor environment as well as quality
considerations are important element in the study of energy consumption, thermal comfort
and indoor air quality in buildings. This paper investigate a comparison work between
impinging jet, displacement, and mixing ventilation systems for an isothermal and nonisothermal ventilated room for Indoor Air Quality (IAQ) and thermal human comfort under
Iraqi climate. For IJV system, draught discomfort is the issue of most concern since it
supplies cooled air directly to the occupied zone. This study investigated a number of factors
influencing draught discomfort and temperature stratification in an office environment. The
considered factors, supply airflow rate and supply air temperature. RNG K-Ɛ turbulence
model was used with the turbulent flow. The second aspect included numerical analyses by
adopting ANSYS FLUENT15 code to generate simulation models. A square shaped air
supply device was used with [0.1 times room height (h)] outlet terminal height from the foot
level end. The IJV system proved more efficient than displacement and mixing ventilation
systems. The Air Distribution Performance Index (ADPI) obtained for an isothermal and
non-isothermal ventilated room adopting IJV system gave best values (0.80, 0.83)
respectively compared with the other two ventilation systems

Friction stir processing (FSP) is a new solid state technique, it is employed for the
improvement of the mechanical properties of a material and the production of surface layer
composites instead of conventional processing technologies. This research aims to study the
ability of applying Friction Stir Processing (FSP) to modify the surface of high density
polyethylene (HDPE) reinforcing by B4C with a particle size of 0.4μm, Groove in the
middle of HDPE surface made to fill by B4C. Varity in the groove depth (0.6, 1.2 and
1.8)mm used according to B4C ratio on HDPE substrate particles. Friction stir process was
carried out, using tool with cylindrical shape of pin and shoe tool to produce surface layer
composite. The effect of processing parameters including rotational and transverse speeds on
the mechanical properties of composite layer was studied. Wear test results show a
pronounced improvement in wear resistance of HDPE surface through reinforcement
additions of B4C at a ratio (5%, 10% and 15% ), where wear rate improved by (60%, 71%
and 63%) respectively, as compared with as received HDPE, the surface composite
HDPE/B4C have good wear resistance. Hardness test results indicate that the hardness of
composite layer reinforced with (5%,10% and 15%) particles improved by( 26%, 35% and
28% )respectively as compared with received HDPE. OM revealed that hig

An experimental study was done to investigate the effect of fin geometry
modification and material type on heat dissipation from a heat sink under natural convection.
v-corrugated solid fin and v-corrugated perforated fin were designed for this purpose.
Aluminum and Copper metals were selected in designing the fins because their wide
application in cooling and heating equipment. Three different voltages 110, 150 and 200 V
supplied to the heat sink to study their effects on the fins performance. Each experiment
repeats two times to reduce the error and the data recorded after reaching the steady state
conditions. The utilization of solid and perforated v-corrugated fins is compared. The results
showed that perforated fins dissipated heat more than corresponding solid by 15.4, 34 and
32% for aluminum, and 2.7, 2.1 and 4.3% for copper fin in the three voltages. Also, the
results indicated that the heat loss by solid copper fin is greater by 56, 72 and 92% than
corresponding solid aluminum fin and for perforated fin case by 38, 31.7 and 51.9 % at
110,150 and 200 V respectively.

In this paper, studying synthesis zinc oxide nanoparticles (ZnO NPs) via sol - gel method
and effect of adding polymer in preparation its solution. Zinc nitrate hexahydrate,
Polyvinylpyrrolidone PVP, distilled water and sodium hydroxide (NaOH) were used as
precursor materials. Crystallization behavior of the ZnO was studied by X-ray diffraction
(XRD). Nanoparticles phases can change from amorphous to wurtzite structure at the
calcination temperature (500 °C) and crystallite size by Scherrer’s formula about (21.131)
nm for samples prepared with distilled water and (20.035)nm for samples prepared with
dissolved PVP. Morphological and structural properties were investigated by scanning
electron microscopy (SEM). FT-IR spectra was indicated characteristic absorption bands of
ZnO. UV-Vis absorption spectrum was shown a typical spectrum for ZnO nanoparticles.
Finally, the results were shown the samples with dissolved PVP has smaller particles size,
less agglomeration and narrow distribution but less purity phase when compared with
samples prepared with distilled water.

This paper studies the preparation of Copper powder from Copper Sulphate aqueous
solution(CuSO4.5H2O), sulfuric acid (H2SO4) and copper chloride (CuCl2.2H2O)by using
the process of electro-deposition. Process of Powder deposition have been investigated for
copper powder, it is a fine layer on cathode electrode by using the value of different from
current densities (0.12, 0.14, 0.16, and 0.18) A/cm2
.as it is noticed the weight of the powder
rises with there is of current density. Diffractions of X-ray (XRD) revealed high crystallinity
and pure copper powder not contain impurity or oxides. Size of the Crystallite has been
measured by Scherrer's Formula about (38.44 -43.161) nm. Optical microscopes have
revealed the particles of copper have dendritic shapes. The size of Particles analyzer
measured the size of a particle which is about (2.4 – 8.7) μm.

This work is aimed to study the dynamic behavior and control of the triple invertedpendulum system. A nonlinear dynamic model of the inverted-pendulums fixed on a cart,
based on CAD model is developed. The Lagrange equation is used to obtain the nonlinear
dynamic models of the system. The dynamic model is then linearized around operating
point. An augmented dynamic model using the linearized model is also derived. Two control
approaches are used to stabilize the pendulums in vertical position. First approach: State
Feedback Control based on the linearized model is used to generate the input force control to
stabilize the system. Second approach: Model Predictive Control is designed based on
augmented dynamic Model to control the motion of the system. In order to verify the
developed model and the chosen controller gains several simulations for different carts’
paths are carried out. Several 3D animations are also presented to verify the usefulness of
the designed CAD model and the controllers. As a future work: the 3D model of the triple
inverted-pendulum system gives a valuable resource for virtual reality work. Beside, another
advanced control approach can be applied on the derived dynamic model.

Low alloy steels are particularly used in manufacturing several parts in the heavy
engineering industries, agricultural equipment and dies which may be subject to service
failure, and thus may need to be repaired by one of the welding processes. The weldability
of steels is determined by their sensitivity to cracks that can be prevented by the use of
special welding procedures which are often expensive and difficult to use. Manual metal arc
welding of low alloy high strength steels was done firstly, using a cheap electrode (OK
46.00), followed by the use of an economical technique which depends on coiling copper
wires with different diameters around the cheap electrode. The expensive electrode (OK
73.68) was also used for comparison. Results showed an increase in the tensile strength (712
MPa) and weld joint efficiency (83.8%) when the expensive iron powder low hydrogen
covering electrode (OK 73.68) was used. On the other hand, the tensile strength was
decreased to (206 MPa) and the weld joint efficiency to (24.2%) when the cheap electrode
(OK 46.00) was used. Coiling a (0.6 mm) dia. copper wire around the (OK 46.00) electrode
increased the tensile strength and weld joint efficiency to (510 MPa) and (60%) respectively.