Abstract: To develop AZ91D magnesium alloys with improved
properties, we have applied TiN and VN/TiN multilayer coatings
using DC magnetron sputter technique. Coating structure, surface
morphology, chemical bonding and corrosion resistance of coatings
were analyzed by x-ray diffraction (XRD), scanning electron
microscope (SEM), x-ray photoelectron spectroscopy (XPS), and
tafel extrapolation method, respectively. XPS analysis reveal that VN
overlayer reacts with oxygen at the VN/TiN interface and forms more
stable TiN layer. Morphological investigations and the corrosion
results show that VN/TiN multilayer thin film coatings are quite
effective to optimize the corrosion resistance of Mg alloys.
Abstract: Machining parameters are very important in
determining the surface quality of any material. In the past decade,
some new engineering materials were developed for the
manufacturing industry which created a need to conduct an
investigation on the impact of the said parameters on their surface
roughness. Polyurethane (PU) block is widely used in the automotive
industry to manufacture parts such as checking fixtures that are used
to verify the dimensional accuracy of automotive parts. In this paper,
the design of experiment (DOE) was used to investigate on the effect
of the milling parameters on the PU block. Furthermore, an analysis
of the machined surface chemical composition was done using
scanning electron microscope (SEM). It was found that the surface
roughness of the PU block is severely affected when PU undergoes a
flood machining process instead of a dry condition. In addition the
stepover and the silicon content were found to be the most significant
parameters that influence the surface quality of the PU block.
Abstract: Metal matrix composites (MMCs) attract considerable
attention as a result from its ability in providing a high strength, high
modulus, high toughness, high impact properties, improving wear
resistance and providing good corrosion resistance compared to
unreinforced alloy. Aluminium Silicon (Al/Si) alloy MMC has been
widely used in various industrial sectors such as in transportation,
domestic equipment, aerospace, military, construction, etc.
Aluminium silicon alloy is an MMC that had been reinforced with
aluminium nitrate (AlN) particle and become a new generation
material use in automotive and aerospace sector. The AlN is one of
the advance material that have a bright prospect in future since it has
features such as lightweight, high strength, high hardness and
stiffness quality. However, the high degree of ceramic particle
reinforcement and the irregular nature of the particles along the
matrix material that contribute to its low density is the main problem
which leads to difficulties in machining process. This paper examined
the tool wear when milling AlSi/AlN Metal Matrix Composite using
a TiB2 (Titanium diboride) coated carbide cutting tool. The volume
of the AlN reinforced particle was 10% and milling process was
carried out under dry cutting condition. The TiB2 coated carbide
insert parameters used were at the cutting speed of (230, 300 and
370m/min, feed rate of 0.8, Depth of Cut (DoC) at 0.4m). The
Sometech SV-35 video microscope system used to quantify of the
tool wear. The result shown that tool life span increasing with the
cutting speeds at (370m/min, feed rate of 0.8mm/tooth and DoC at
0.4mm) which constituted an optimum condition for longer tool life
lasted until 123.2 mins. Meanwhile, at medium cutting speed which
at 300m/m, feed rate of 0.8mm/tooth and depth of cut at 0.4mm we
found that tool life span lasted until 119.86 mins while at low cutting
speed it lasted in 119.66 mins. High cutting speed will give the best
parameter in cutting AlSi/AlN MMCs material. The result will help
manufacturers in machining process of AlSi/AlN MMCs materials.
Abstract: Heavy rare earth (HRE) oxalate concentrates were
prepared from the Egyptian crude monazite sand (graded about 47%).
The concentrates were specified quantitatively for their constituents
of individual rare earth elements using ion chromatograph (IC) and
qualitatively by scanning electron microscope (SEM) for the other
major constituents. The 1st concentrate was composed of 10.5%
HREE where 7.25% of them represented yttrium. The 2nd concentrate
contained about 41.7% LREE, 17.5% HREE and 13.6% Th. The
LREE involved 18.3% Ce, 10.5% La and 8% Nd while the HREE
were 8.7% Y, 3.5% Gd and 2.9% Dy. The 3rd concentrate was
containing about 8.0% LREE (3.7% Ce, 2.0% La and 1.5% Nd),
10.2% HREE (6.4% yttrium and 2.0% Dy) and 2.1% uranium. The
final concentrate comprised 0.84% uranium beside iron, chromium
and traces of REE.
Abstract: The study is devoted to define the optimal conditions
for the nitriding of pure iron at atmospheric pressure by using NH3-
Ar-C3H8 gas mixtures. After studying the mechanisms of phase
formation and mass transfer at the gas-solid interface, a mathematical
model is developed in order to predict the nitrogen transfer rate in the
solid, the ε-carbonitride layer growth rate and the nitrogen and
carbon concentration profiles. In order to validate the model and to
show its possibilities, it is compared with thermogravimetric
experiments, analyses and metallurgical observations (X-ray
diffraction, optical microscopy and electron microprobe analysis).
Results obtained allow us to demonstrate the sound correlation
between the experimental results and the theoretical predictions.
Abstract: Many of the ever-growing elderly population require
exercise, such as running, for health management. One important
element of a runner’s training is the choice of shoes for exercise; shoes
are important because they provide the interface between the feet and
road. When we purchase shoes, we may instinctively choose a pair
after trying on many different pairs of shoes. Selecting the shoes
instinctively may work, but it does not guarantee a suitable fit for
running activities. Therefore, if we could select suitable shoes for each
runner from the viewpoint of brain activities, it would be helpful for
validating shoe selection. In this paper, we describe how brain
activities show different characteristics during particular task,
corresponding to different properties of shoes. Using five subjects, we
performed a verification experiment, applying weight, softness, and
flexibility as shoe properties. In order to affect the shoe property’s
differences to the brain, subjects run for 10 min. Before and after
running, subjects conducted a paced auditory serial addition task
(PASAT) as the particular task; and the subjects’ brain activities
during the PASAT are evaluated based on oxyhemoglobin and
deoxyhemoglobin relative concentration changes, measured by
near-infrared spectroscopy (NIRS). When the brain works actively,
oxihemoglobin and deoxyhemoglobin concentration drastically
changes; therefore, we calculate the maximum values of concentration
changes. In order to normalize relative concentration changes after
running, the maximum value are divided by before running maximum
value as evaluation parameters. The classification of the groups of
shoes is expressed on a self-organizing map (SOM). As a result,
deoxyhemoglobin can make clusters for two of the three types of
shoes.
Abstract: Carbon nanotube is one of the most attractive materials
for the potential applications of nanotechnology due to its excellent
mechanical, thermal, electrical and optical properties. In this paper we
report a supercapacitor made of nickel foil electrodes, coated with
multiwall carbon nanotubes (MWCNTs) thin film using
electrophoretic deposition (EPD) method. Chemical vapor deposition
method was used for the growth of MWCNTs and ethanol was used as
a hydrocarbon source. High graphitic multiwall carbon nanotube was
found at 750oC analyzing by Raman spectroscopy. We observed the
electrochemical performance of supercapacitor by cyclic
voltammetry. The electrodes of supercapacitor fabricated from
MWCNTs exhibit considerably small equivalent series resistance
(ESR), and a high specific power density. Electrophoretic deposition
is an easy method in fabricating MWCNT electrodes for high
performance supercapacitor.
Abstract: In this study, epoxy composite specimens reinforced
with multi-walled carbon nanotube filler were fabricated using shear
mixer and ultra-sonication processor. The mechanical and thermal
properties of the fabricated specimens were measured and evaluated.
From the electron microscope images and the results from the
measurements of tensile strengths, the specimens having 0.6 wt%
nanotube content show better dispersion and higher strength than those
of the other specimens. The Young’s moduli of the specimens
increased as the contents of the nanotube filler in the matrix were
increased. The specimen having a 0.6 wt% nanotube filler content
showed higher thermal conductivity than that of the other specimens.
While, in the measurement of thermal expansion, specimens having
0.4 and 0.6 wt% filler contents showed a lower value of thermal
expansion than that of the other specimens. On the basis of the
measured and evaluated properties of the composites, we believe that
the simple and time-saving fabrication process used in this study was
sufficient to obtain improved properties of the specimens.
Abstract: PVC foam-fly ash composites (PVC-FA) are
characterized for their structural, morphological, mechanical and
thermal properties. The tensile strength of the composites increased
modestly with higher fly ash loading, while there was a significant
increase in the elastic modulus for the same composites. On the other
hand, a decrease in elongation at UTS was observed upon increasing
fly ash content due to increased rigidity of the composites. Similarly,
the flexural modulus increased as the fly ash loading increased,
where the composites containing 25 phr fly ash showed the highest
flexural strength. Thermal properties of PVC-fly ash composites were
determined by Thermo Gravimetric Analysis (TGA). The
microstructural properties were studied by Scanning Electron
Microscopy (SEM). SEM results confirm that fly ash particles were
mechanically interlocked in PVC matrix with good interfacial
interaction with the matrix. Particle agglomeration and debonding
was observed in samples containing higher amounts of fly ash.
Abstract: We report on the use of strong external optical
feedback to enhance the modulation response of semiconductor lasers
over a frequency passband around modulation frequencies higher
than 60 GHz. We show that this modulation enhancement is a type of
photon-photon resonance (PPR) of oscillating modes in the external
cavity formed between the laser and the external reflector. The study
is based on a time-delay rate equation model that takes into account
both the strong feedback and multiple reflections in the external
cavity. We examine the harmonic and intermodulation distortions
associated with single and two-tone modulations in the mm-wave
band of the resonant modulation. We show that compared with
solitary lasers modulated around the carrier-photon resonance
frequency, the present mm-wave modulated signal has lower
distortions.
Abstract: Today’s modern interconnected power system is
highly complex in nature. In this, one of the most important
requirements during the operation of the electric power system is the
reliability and security. Power and frequency oscillation damping
mechanism improve the reliability. Because of power system
stabilizer (PSS) low speed response against of major fault such as
three phase short circuit, FACTs devise that can control the network
condition in very fast time, are becoming popular. But FACTs
capability can be seen in a major fault present when nonlinear models
of FACTs devise and power system equipment are applied. To realize
this aim, the model of multi-machine power system with FACTs
controller is developed in MATLAB/SIMULINK using Sim Power
System (SPS) blockiest. Among the FACTs device, Static
synchronous series compensator (SSSC) due to high speed changes
its reactance characteristic inductive to capacitive, is effective power
flow controller. Tuning process of controller parameter can be
performed using different method. But Genetic Algorithm (GA)
ability tends to use it in controller parameter tuning process. In this
paper firstly POD controller is used to power oscillation damping.
But in this station, frequency oscillation dos not has proper damping
situation. So FOD controller that is tuned using GA is using that
cause to damp out frequency oscillation properly and power
oscillation damping has suitable situation.
Abstract: Corrosion inhibitors are widely used in concrete
industry to reduce the corrosion rate of steel rebar which is present in
contact with aggressive environments. The present work aims to
using Zamzam water from well located within the Masjid al-Haram
in Mecca, Saudi Arabia 20 m (66 ft) east of the Kaaba, the holiest
place in Islam as corrosion inhibitor for steel in rain water and
simulated acid rain. The effect of Zamzam water was investigated by
electrochemical impedance spectroscopy (EIS) and Potentiodynamic
polarization techniques in Department of Civil Engineering - IUT
Saint-Nazaire, Nantes University, France. Zamzam water is
considered to be one of the most important steel corrosion inhibitor
which is frequently used in different industrial applications. Results
showed that zamzam water gave a very good inhibition for steel
corrosion in rain water and simulated acid rain.
Abstract: The present study was conducted to evaluate the
potential applicability of biological trickling filter system for the
treatment of simulated textile wastewater containing reactive azo
dyes with bacterial consortium under non-sterile conditions. The
percentage decolorization for the treatment of wastewater containing
structurally different dyes was found to be higher than 95% in all
trials. The stable bacterial count of the biofilm on stone media of the
trickling filter during the treatment confirmed the presence,
proliferation, dominance and involvement of the added microbial
consortium in the treatment of textile wastewater. Results of
physicochemical parameters revealed the reduction in chemical
oxygen demand (58.5-75.1%), sulphates (18.9-36.5%), and
phosphates (63.6-73.0%). UV-Visible and FTIR spectroscopy
confirmed decolorization of dye containing wastewater was ultimate
consequence of biodegradation. Toxicological studies revealed the
nontoxic nature of degradative metabolites.
Abstract: Two Lithium Disilicate (LD) glass ceramics based on
SiO2-Li2O-K2O-Al2O3 system were prepared through a glass melting
method. The glass rods were then fabricated into dental crowns via a
hot pressing at 900˚C and 850˚C in order to study the effect of the
pressing temperatures on the phase formation and microstructure of
the glasses. Different samples of as cast glass and heat treated
samples (600˚C and 700˚C) were used to press for investigating the
effect of an initial microstructure on the hot pressing technique. Xray
diffraction (XRD) and scanning electron microscopy (SEM) were
performed to determine the phase formation and microstructure of the
samples, respectively. XRD results show that the main crystalline
structure was Li2Si2O5 by having Li3PO4, Li0.6Al0.6Si2O6, Li2SiO3,
Ca5 (PO4)3F and SiO2 as minor phases. Glass compositions with
different heat treatment temperatures exhibited a difference phase
formations but have less effect during pressing. SEM micrographs
showed the microstructure of Li2Si2O5 as lath-like shape in all
glasses. With increasing the initial heat treatment temperature, the
longer the lath-like crystals of lithium disilicate were increased
especially when using glass heat treatment at 700˚C followed by
pressing at 900˚C. This could be suggested that LD1 heat treatment at
700˚C which pressing at 900˚C presented the best formation by the
hot pressing and compiled microstructure.
Abstract: In this work, a polyaniline/Iron oxide (PANI/Fe2O3)
composite was chemically prepared by oxidative polymerization of
aniline in acid medium, in presence of ammonium persulphate as an
oxidant and amount of Fe2O3. The composite was characterized by a
scanning electron microscopy (SEM). The prepared composite has
been used as adsorbent to remove Tartrazine dye form aqueous
solutions.
The effects of initial dye concentration and temperature on the
adsorption capacity of PANI/Fe2O3 for Tartrazine dye have been
studied in this paper.
The Langmuir and Freundlich adsorption models have been used
for the mathematical description of adsorption equilibrium data. The
best fit is obtained using the Freundlich isotherm with an R2 value of
0.998. The change of Gibbs energy, enthalpy, and entropy of
adsorption has been also evaluated for the adsorption of Tartrazine
onto PANI/ Fe2O3. It has been proved according the results that the
adsorption process is endothermic in nature.
Abstract: Violet Sr–Al–O:Eu2+ phosphor particles were
synthesized from a metal–ethylenediaminetetraacetic acid (EDTA)
solution of Sr, Al, Eu, and particulate alumina via spray drying and
sintering in a reducing atmosphere. The crystal structures and emission
properties at 85–300 K were investigated. The composition of the
violet Sr–Al–O:Eu2+ phosphor particles was determined from various
Sr–Al–O:Eu2+ phosphors by their emission properties’ dependence
on temperature. The highly crystalline SrAl12O19:Eu2+ emission phases
were confirmed by their crystallite sizes and the activation energies for
the 4f5d–8S7/2 transition of the Eu2+ ion. These results showed that the
material identification for the violet Sr–Al–O:Eu2+ phosphor was
accomplished by the low-temperature luminescence measurements.
Abstract: We have experimentally demonstrated bright-dark
pulses in a nonlinear polarization rotation (NPR) based mode-locked
Erbium-doped fiber laser (EDFL) with a long cavity configuration.
Bright–dark pulses could be achieved when the laser works in the
passively mode-locking regime and the net group velocity dispersion
is quite anomalous. The EDFL starts to generate a bright pulse train
with degenerated dark pulse at the mode-locking threshold pump
power of 35.09 mW by manipulating the polarization states of the
laser oscillation modes using a polarization controller (PC). A split
bright–dark pulse is generated when further increasing the pump
power up to 37.95 mW. Stable bright pulses with no obvious
evidence of a dark pulse can also be generated when further adjusting
PC and increasing the pump power up to 52.19 mW. At higher pump
power of 54.96 mW, a new form of bright-dark pulse emission was
successfully identified with the repetition rate of 29 kHz. The bright
and dark pulses have a duration of 795.5 ns and 640 ns, respectively.
Abstract: A modeling approach for CMOS gates is presented
based on the use of the equivalent inverter. A new model for the
inverter has been developed using a simplified transistor current
model which incorporates the nanoscale effects for the planar
technology. Parametric expressions for the output voltage are
provided as well as the values of the output and supply current to be
compatible with the CCS technology. The model is parametric
according the input signal slew, output load, transistor widths, supply
voltage, temperature and process. The transistor widths of the
equivalent inverter are determined by HSPICE simulations and
parametric expressions are developed for that using a fitting
procedure. Results for the NAND gate shows that the proposed
approach offers sufficient accuracy with an average error in
propagation delay about 5%.
Abstract: This paper represents performance of particle swarm
optimisation (PSO) algorithm based integral (I) controller and
proportional-integral controller (PI) for interconnected hydro-thermal
automatic generation control (AGC) with generation rate constraint
(GRC) and Thyristor controlled phase shifter (TCPS) in series with
tie line. The control strategy of TCPS provides active control of
system frequency. Conventional objective function integral square
error (ISE) and another objective function considering square of
derivative of change in frequencies of both areas and change in tie
line power are considered. The aim of designing the objective
function is to suppress oscillation in frequency deviations and change
in tie line power oscillation. The controller parameters are searched
by PSO algorithm by minimising the objective functions. The
dynamic performance of the controllers I and PI, for both the
objective functions, are compared with conventionally optimized I
controller.
Abstract: The influence of three different types of halloysite
nanotubes (HNTs) with different dimensions, namely as camel lake
(CLA), Jarrahdale (JA) and Matauri Bay (MB), on their reinforcing
ability of ethylene propylene dine monomer (EPDM) were
investigated by varying the HNTs loading (from 0-15 phr).
Mechanical properties of the nanocomposites improved with addition
of all three HNTs, but CLA based nanocomposites exhibited a
significant enhancement compared to the other HNTs. For instance,
tensile properties of EPDM nanocomposites increased by 120%,
256% and 340% for MB, JA and CLA, respectively, with addition of
15 phr of HNTs. This could be due to the higher aspect ratio and
higher surface area of CLA compared to others. Scanning electron
microscopy (SEM) of nanocomposites at 15 phr of HNT loadings
showed low amounts of pulled-out nanotubes which confirmed the
presence of more embedded nanotubes inside the EPDM matrix, as
well as aggregates within the fracture surface of EPDM/HNT
nanocomposites