Abstract: A composite made of plasma functionalized multiwall
carbon nanotubes (MWNTs) coated with SnO2 was synthesized by
sonochemical precipitation method. Thick layer of this
nanocomposite material was used as ethanol sensor at low
temperatures. The composite sensitivity for ethanol has increased by
a factor of 2 at room temperature and by a factor of 13 at 250°C in
comparison to that of pure SnO2. SEM image of nanocomposite
material showed MWNTs were embedded in SnO2 matrix and also a
higher surface area was observed in the presence of functionalized
MWNTs. Greatly improved sensitivity of the composite material to
ethanol can be attributed to new gas accessing passes through
MWNTs and higher specific surface area.
Abstract: This paper investigates the development of weld zone
in Resistance Spot Welding (RSW) which focuses on weld nugget and Heat Affected Zone (HAZ). The effects of four factors namely
weld current, weld time, electrode force and hold time were studied using a general 24 factorial design augmented by five centre points. The results of the analysis showed that all selected factors except
hold time exhibit significant effect on weld nugget radius and HAZ size. Optimization of the welding parameters (weld current, weld
time and electrode force) to normalize weld nugget and to minimize
HAZ size was then conducted using Central Composite Design (CCD) in Response Surface Methodology (RSM) and the optimum
parameters were determined. A regression model for radius of weld nugget and HAZ size was developed and its adequacy was evaluated.
The experimental results obtained under optimum operating conditions were then compared with the predicted values and were
found to agree satisfactorily with each other
Abstract: The aim of the work was to attenuate the vibration amplitude in CESNA 172 airplane wing by using Functionally Graded Material instead of uniform or composite material. Wing strength was achieved by means of stress analysis study, while wing vibration amplitudes and shapes were achieved by means of Modal and Harmonic analysis. Results were verified by applying the methodology in a simple cantilever plate to the simple model and the results were promising and the same methodology can be applied to the airplane wing model. Aluminum models, Titanium models, and functionally graded materials of Aluminum and titanium results were compared to show a great vibration attenuation after using the FGM. Optimization in FGM gradation satisfied our objective of reducing and attenuating the vibration amplitudes to show the effect of using FGM in vibration behavior. Testing the Aluminum rich models, and comparing it with the titanium rich model was an optimization in this paper. Results have shown a significant attenuation in vibration magnitudes when using FGM instead of Titanium Plate, and Aluminium wing with FGM Spurs instead of Aluminium wings. It was also recommended that in future, changing the graphical scale to 1:10 or even 1:1 when the computers- capabilities allow.
Abstract: Sport is one of the sectors in which the largest
technical projections regarding the functions of textiles can be found.
He is a large consumer of high performance composite materials and
new fibers. It is one of the sectors where the innovation is the most
important when the greatest numbers of spectacular developments are
aimed at increasing performance. In medicine, textile innovation is
used and contributes in the amelioration of different materials such as
dressing, orthosis, bandages, etc. The hygienic textiles in non-woven
materials record a strong growth. The objective of this study is to
show the different advances of development we obtained in the both
ways (sport and medicine). Polyamide fibers where developed
tacking into account the specification of the high level athlete’s
performance like swimming and triathlon (Olympic Games, Brazil
2016). The first textile utilization was for skiing (Olympic Games,
Sotchi 2014). The different textiles technologies where adapted for
medicine.
Abstract: This study has applied the L16 orthogonal array of the
Taguchi method to determine the optimized polymeric
Nanocomposite asphalt binder. Three control factors are defined as
polypropylene plastomer (PP), styrene-butadiene-styrene elastomer
(SBS) and Nanoclay. Four level of concentration contents are
introduced for prepared asphalt binder samples. all samples were
prepared with 4.5% of bitumen 60/70 content. Compressive strength
tests were carried out for defining the optimized sample via
QUALITEK-4 software. SBS with 3%, PP with 5 % and Nanoclay
with 1.5% of concentrations are defined as the optimized
Nanocomposite asphalt binders. The confirmation compressive
strength and also softening point tests showed that modification of
asphalt binders with this method, improved the compressive strength
and softening points of asphalt binders up to 55%.
Abstract: Alkali treated oil palm empty fruit bunch (EFB) fibres
(TEFBF) and untreated EFBF fibers (UEFBF) were incorporated in
polypropylene (PP) with and without malic anhydride grafted PP
(MAPP) and magnesium hydroxide as flame retardant (FR) to
produce TEFBF-PP and UEFBF-PP composites by the melt casting
method. The composites were characterized by mechanical and
burning tests along with a scanning electron microscope and Fourier
transform infrared spectroscopy. The significant improvement in
flexural modulus (133%) and flame retardant property (60%) of
TEFBF-PP composite with MAPP and FR is observed. The improved
mechanical property is discussed by the development of encapsulated
textures.
Abstract: This paper presents the effect of corrugation profile
geometry on the crushing behavior, energy absorption, failure
mechanism, and failure mode of woven roving glass fibre/epoxy
laminated composite tube. Experimental investigations were carried
out on composite tubes with three different profile shapes: sinusoidal,
triangular and trapezoidal. The tubes were subjected to lateral
compressive loading. On the addition to a radial corrugated
composite tube, cylindrical composite tube, were fabricated and
tested under the same condition in order to know the effect of
corrugation geometry. Typical histories of their deformation are
presented. Behavior of tubes as regards the peak crushing load,
energy absorbed and mode of crushing has been discussed. The
results show that the behavior of the tube under lateral compression
load is influenced by the geometry of the tube itself.
Abstract: This paper describes a study of geometrically
nonlinear free vibration of thin circular functionally graded (CFGP)
plates resting on Winkler elastic foundations. The material properties
of the functionally graded composites examined here are assumed to
be graded smoothly and continuously through the direction of the
plate thickness according to a power law and are estimated using the
rule of mixture. The theoretical model is based on the classical Plate
theory and the Von-Kármán geometrical nonlinearity assumptions.
An homogenization procedure (HP) is developed to reduce the
problem considered here to that of isotropic homogeneous circular
plates resting on Winkler foundation. Hamilton-s principle is applied
and a multimode approach is derived to calculate the fundamental
nonlinear frequency parameters which are found to be in a good
agreement with the published results. On the other hand, the
influence of the foundation parameters on the nonlinear fundamental
frequency has also been analysed.
Abstract: In recent years, rehabilitation has been the subject of extensive research due to increased spending on building work and repair of built works. In all cases, it is absolutely essential to carry out methods of strengthening or repair of structural elements, and that following an inspection analysis and methodology of a correct diagnosis. The reinforced concrete columns are important elements in building structures. They support the vertical loads and provide bracing against the horizontal loads. This research about the behavior of reinforced concrete rectangular columns, rehabilitated by concrete liner, confinement FRP fabric, steel liner or cage formed by metal corners. It allows comparing the contributions of different processes used perspective section resistance elements rehabilitated compared to that is not reinforced or repaired. The different results obtained revealed a considerable gain in bearing capacity failure of reinforced sections cladding concrete, metal bracket, steel plates and a slight improvement to the section reinforced with fabric FRP. The use of FRP does not affect the weight of the structures, but the use of different techniques cladding increases the weight of elements rehabilitated and therefore the weight of the building which requires resizing foundations.
Abstract: Optimization of extraction of phenolic compounds
from Avicennia marina using response surface methodology was
carried out during the present study. Five levels, three factors
rotatable design (CCRD) was utilized to examine the optimum
combination of extraction variables based on the TPC of Avicennia
marina leaves. The best combination of response function was 78.41
°C, drying temperature; 26.18°C; extraction temperature and 36.53
minutes of extraction time. However, the procedure can be promptly
extended to the study of several others pharmaceutical processes like
purification of bioactive substances, drying of extracts and
development of the pharmaceutical dosage forms for the benefit of
consumers.
Abstract: An aqueous methanol sensor for use in direct
methanol fuel cells (DMFCs) applications is demonstrated; the
methanol sensor is built using dispersed single-walled carbon
nanotubes (SWCNTs) with Nafion117 solution to detect the methanol
concentration in water. The study is aimed at the potential use of the
carbon nanotubes array as a methanol sensor for direct methanol fuel
cells (DMFCs). The concentration of methanol in the fuel circulation
loop of a DMFC system is an important operating parameter, because
it determines the electrical performance and efficiency of the fuel cell
system. The sensor is also operative even at ambient temperatures
and responds quickly to changes in the concentration levels of the
methanol. Such a sensor can be easily incorporated into the methanol
fuel solution flow loop in the DMFC system.
Abstract: Toughening of polyamide 6 (PA6)/ Nanoclay (NC) nanocomposites with styrene-ethylene/butadiene-styrene copolymer (SEBS) using maleated styrene-ethylene/butadiene-styrene copolymer (mSEBS)/ as a compatibilizer were investigated by blending them in a co-rotating twin-screw extruder. Response surface method of experimental design was used for optimizing the material and processing parameters. Effect of four factors, including SEBS, mSEBS and NC contents as material variables and order of mixing as a processing factor, on toughness of hybrid nanocomposites were studied. All the prepared samples showed ductile behavior and low temperature Izod impact toughness of some of the hybrid nanocomposites demonstrated 900% improvement compared to the PA6 matrix while the modulus showed maximum enhancement of 20% compared to the pristine PA6 resin.
Abstract: With the development of the Polyvinyl chloride
(PVC) products in many applications, the challenge of investigating
the raw material composition and reducing the cost have both
become more and more important. Considerable research has been
done investigating the effect of additives on the PVC products. Most
of the PVC composites research investigates only the effect of
single/few factors, at a time. This isolated consideration of the input
factors does not take in consideration the interaction effect of the
different factors. This paper implements a mixture experimental
design approach to find out a cost-effective PVC composition for the
production of electrical-insulation cables considering the ASTM
Designation (D) 6096. The results analysis showed that a minimum
cost can be achieved through using 20% virgin PVC, 18.75%
recycled PVC, 43.75% CaCO3 with participle size 10 microns, 14%
DOP plasticizer, and 3.5% CPW plasticizer. For maximum UTS the
compound should consist of: 17.5% DOP, 62.5% virgin PVC, and
20.0% CaCO3 of particle size 5 microns. Finally, for the highest
ductility the compound should be made of 35% virgin PVC, 20%
CaCO3 of particle size 5 microns, and 45.0% DOP plasticizer.
Abstract: In the present work, we have developed a symmetric electrochemical capacitor based on the nanostructured iron oxide (Fe3O4)-activated carbon (AC) nanocomposite materials. The physical properties of the nanocomposites were characterized by Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The electrochemical performances of the composite electrode in 1.0 M Na2SO3 and 1.0 M Na2SO4 aqueous solutions were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The composite electrode with 4 wt% of iron oxide nanomaterials exhibits the highest capacitance of 86 F/g. The experimental results clearly indicate that the incorporation of iron oxide nanomaterials at low concentration to the composite can improve the capacitive performance, mainly attributed to the contribution of the pseudocapacitance charge storage mechanism and the enhancement on the effective surface area of the electrode. Nevertheless, there is an optimum threshold on the amount of iron oxide that needs to be incorporated into the composite system. When this optimum threshold is exceeded, the capacitive performance of the electrode starts to deteriorate, as a result of the undesired particle aggregation, which is clearly indicated in the SEM analysis. The electrochemical performance of the composite electrode is found to be superior when Na2SO3 is used as the electrolyte, if compared to the Na2SO4 solution. It is believed that Fe3O4 nanoparticles can provide favourable surface adsorption sites for sulphite (SO3 2-) anions which act as catalysts for subsequent redox and intercalation reactions.
Abstract: The objective was to determine the single gene and
interaction effect of composite genotype of beta-kappa casein and
DGAT1 gene on milk yield (MY) and milk composition, content of
milk fat (%FAT), milk protein (%PRO), solid not fat (%SNF), and
total solid (%TS) in crossbred Holstein cows. Two hundred and
thirty- one cows were genotyped with PCR-RFLP for DGAT1 and
composite genotype data of beta-kappa casein from previous work
were used. Two model, (1), and (2), was used to estimate single gene
effect, and interaction effect on the traits, respectively. The
significance of interaction effects on all traits were detected. Most
traits have consistent pattern of significant when model (1), and (2)
were compared, except the effect of composite genotype of betakappa
casein on %FAT, and the effect of DGAT1 on MY, which the
significant difference was detected in only model (1).The results
suggested that when the optimum of all traits was necessary,
interaction effect should be concerned.
Abstract: Composite steel shear wall is a lateral load resisting system which consists of a steel plate with concrete wall attached to one or both sides to prevent it from elastic buckling. The composite behavior is ensured by utilizing high-strength bolts. This paper investigates the effect of distance between bolts, and for this purpose 14 one-story one-bay specimens with various bolts spacing were modeled by finite element code which is developed by the authors. To verify the model, numerical results were compared with a valid experiment which illustrate proper agreement. Results depict increasing the distance between bolts would improve the seismic ever, this increase must be limited, because of large distances will cause widespread buckling of the steel plate in free subpanels between bolts and would result in no improvement. By comparing the results in elastic region, it was observed initial stiffness is not affected by changing the distance.
Abstract: Composites based on a biodegradable polycaprolactone (PCL) containing 0.5, 1.0 and 2.0 wt % of titanium dioxide (TiO2) micro and nanoparticles were prepared by melt mixing and the effect of filler type and contents on the thermal properties, dynamic-mechanical behaviour and morphology were investigated. Measurements of storage modulus and loss modulus by dynamic mechanical analysis (DMA) showed better results for microfilled PCL/TiO2 composites than nanofilled composites, with the same filler content. DSC analysis showed that the Tg and Tc of micro and nanocomposites were slightly lower than those of neat PCL. The crystallinity of the PCL increased with the addition of TiO2 micro and nanoparticles; however, the cc for the PCL was unchanged with micro TiO2 content. The thermal stability of PCL/TiO2 composites were characterized using thermogravimetric analysis (TGA). The initial weight loss (5 wt %) occurs at slightly higher temperature with micro and nano TiO2 addition and with increasing TiO2 content.
Abstract: This paper presents the optimal design and development
of an axial flux motor for blood pump application. With the design
objective of maximizing the motor efficiency and torque, different
topologies of AFPM machine has been examined. Selection of
optimal magnet fraction, Halbach arrangement of rotor magnets and
the use of Soft Magnetic Composite (SMC) material for the stator
core results in a novel motor with improved efficiency and torque
profile. The results of the 3D Finite element analysis for the novel
motor have been shown.
Abstract: In this study, the contact problem of a layered composite which consists of two materials with different elastic constants and heights resting on two rigid flat supports with sharp edges is considered. The effect of gravity is neglected. While friction between the layers is taken into account, it is assumed that there is no friction between the supports and the layered composite so that only compressive tractions can be transmitted across the interface. The layered composite is subjected to a uniform clamping pressure over a finite portion of its top surface. The problem is reduced to a singular integral equation in which the contact pressure is the unknown function. The singular integral equation is evaluated numerically and the results for various dimensionless quantities are presented in graphical forms.
Abstract: In this present study, experimental work was
conducted to study the effectiveness of newly innovated steel-CFRP
composite (CFRP laminates sandwiched between two steel strips) as
stirrups. A total numbers of eight concrete beams were tested under
four point loads. Each beam measured 1600 mm long, 160mm width
and 240 mm depth. The beams were reinforced with different shear
reinforcements; one without stirrups, one with steel stirrups and six
with different types and numbers of steel-CRFR stirrups. Test results
indicated that the steel-CFRP stirrups had enhanced the shear
strength capacity of beams. Moreover, the tests revealed that steel-
CFRP stirrups reached to their ultimate tensile strength unlike FRP
stirrups which rupture at much lower level than their ultimate
strength as werereported in various researches.