Abstract: Overhead electrical insulators form an important link in an electric power system. Along with the traditional insulators (i.e. glass and porcelain, etc) presently the polymeric insulators are also used world widely. These polymeric insulators are very sensitive to various environmental parameters such temperature, environmental pollution, UV-radiations, etc. which seriously effect their electrical, chemical and hydrophobic properties. The UV radiation level in the central region of Saudi Arabia is high as compared to the IEC standard for the accelerated aging of the composite insulators. Commonly used suspension type of composite EPDM (Ethylene Propylene Diene Monomer) insulator was subjected to accelerated stress aging as per modified IEC standard simulating the inland arid deserts atmospheric condition and also as per IEC-61109 standard. The hydrophobic characteristics were studied by measuring the contact angle along the insulator surface before and after the accelerated aging of the samples. It was found that EPDM insulator loses it hydrophobic properties proportional to the intensity of UV irradiations and its rate of recovery is also very low as compared to Silicone Rubber insulator.KeywordsEPDM, composite insulators, accelerated aging, hydrophobicity, contact angle.
Abstract: Natural fibres have emerged as the potential reinforcement material for composites and thus gain attraction by many researchers. This is mainly due to their applicable benefits as they offer low density, low cost, renewable, biodegradability and environmentally harmless and also comparable mechanical properties with synthetic fibre composites. The properties of hybrid composites highly depends on several factors, including the interaction of fillers with the polymeric matrix, shape and size (aspect ratio), and orientation of fillers [1]. In this study, natural fibre kenaf composites and kenaf/fibreglass hybrid composites were fabricated by a combination of hand lay-up method and cold-press method. The effect of different fibre types (powder, short and long) on the tensile properties of composites is investigated. The kenaf composites with and without the addition of fibreglass were then characterized by tensile testing and scanning electron microscopy. A significant improvement in tensile strength and modulus were indicated by the introduction of long kenaf/woven fibreglass hybrid composite. However, the opposite trends are observed in kenaf powder composite. Fractographic observation shows that fibre/matrix debonding causes the fibres pull out. This phenomenon results in the fibre and matrix fracture.
Abstract: Although women have merit in their jobs, they still
are located very few in the top management in many sectors. There
are many causes of such situation. Such a situation creates obstacles;
especially invisible ones are called “glass ceiling syndrome”. Also,
studies which handle this subject in academic community are very
few. The aim of this research is to reach the results about glass
ceiling obstacles in terms of female teaching staff (academics)
working in higher education institutions. To this end, our study was
performed on female academics working at Selcuk University, Konya
/ Turkey. Our study's main aim can be expressed as to determine
whether there are glass ceiling obstacles for female academics
working at the higher education institution in question, to measure
their glass ceiling perceptions and, thus, to identify what the glass
ceiling barrier components for them to promotion to senior
management positions are.
Abstract: In this study we present the effect of elevated
temperatures from 300K to 400K on the electrical properties of
copper Phthalocyanine (CuPc) based organic field effect transistors
(OFET). Thin films of organic semiconductor CuPc (40nm) and
semitransparent Al (20nm) were deposited in sequence, by vacuum
evaporation on a glass substrate with previously deposited Ag source
and drain electrodes with a gap of 40 μm. Under resistive mode of
operation, where gate was suspended it was observed that drain
current of this organic field effect transistor (OFET) show an
increase with temperature. While in grounded gate condition metal
(aluminum) – semiconductor (Copper Phthalocyanine) Schottky
junction dominated the output characteristics and device showed
switching effect from low to high conduction states like Zener diode
at higher bias voltages. This threshold voltage for switching effect
has been found to be inversely proportional to temperature and shows
an abrupt decrease after knee temperature of 360K. Change in
dynamic resistance (Rd = dV/dI) with respect to temperature was
observed to be -1%/K.
Abstract: This paper presents a comparative study on dry and wet grinding through experimental investigation in the grinding of CSM glass fibre reinforced polymer laminates using a pink aluminium oxide wheel. Different sets of experiments were performed to study the effects of the independent grinding parameters such as grinding wheel speed, feed and depth of cut on dependent performance criteria such as cutting forces and surface finish. Experimental conditions were laid out using design of experiment central composite design. An effective coolant was sought in this study to minimise cutting forces and surface roughness for GFRP laminates grinding. Test results showed that the use of coolants reduces surface roughness, although not necessarily the cutting forces. These research findings provide useful economic machining solution in terms of optimized grinding conditions for grinding CSM GFRP.
Abstract: Paleoclimate was reconstructed by the clay mineral
assemblages of shale units of Pabdeh (Paleocene- Oligocene), Gurpi
(Upper Cretaceous), Kazhdumi (Albian-Cenomanian) and Gadvan
(Aptian-Neocomian) formations in the Bangestan anticline. To
compare with clay minerals assemblages in these formations,
selected samples also taken from available formations in drilled wells
in Ahvaz, Marun, Karanj, and Parsi oil fields. Collected samples
prepared using standard clay mineral methodology. They were
treated as normal, glycolated and heated oriented glass slides. Their
identification was made on X-Ray diffractographs. Illite % varies
from 8 to 36. Illite quantity increased from Pabdeh to Gurpi
Formation. This may be due to dominant dry climate. Kaolinite is in
range of 12-49%. Its variation style in different formations could be a
marker of climate changes from wet to dry which is supported by the
lithological changes. Chlorite (4-28%) can also be detected in those
samples without any kaolinite. Mixed layer minerals as the mixture
of illite-chlorite and illite-vermiculite-montmorillonite are varied
from 6 to 36%, decreased during Kazhdumi deposition from the base
to the top. This result may be according to decreasing of illite
leaching process. Vermiculite was also determined in very less
quantity and found in those units without kaolinite. Montmorillonite
varies from 8 to 43%, and its presence is due to terrestrial
depositional condition. Stratigraphical documents is also supported
this idea that clay mineral distribution is a function of the climate
changes. It seems, thus, the present results can be indicated a possible
procedure for ancient climate changes evaluation.
Abstract: This work concerns on experimentally investigation
of surfactant flooding in fractured porous media. In this study a series
of water and surfactant injection processes were performed on
micromodels initially saturated with a heavy crude oil. Eight
fractured glass micromodels were used to illustrate effects of
surfactant types and concentrations on oil recovery efficiency in
presence of fractures with different properties i.e. fracture
orientation, length and number of fractures. Two different
surfactants with different concentrations were tested. The results
showed that surfactant flooding would be more efficient by using
SDS surfactant aqueous solution and also by locating injection well
in a proper position respect to fracture properties. This study
demonstrates different physical and chemical conditions that affect
the efficiency of this method of enhanced oil recovery.
Abstract: As is needless to say; a majority of accidents, which occur, are due to drunk driving. As such, there is no effective mechanism to prevent this. Here we have designed an integrated system for the same purpose. Alcohol content in the driver-s body is detected by means of an infrared breath analyzer placed at the steering wheel. An infrared cell directs infrared energy through the sample and any unabsorbed energy at the other side is detected. The higher the concentration of ethanol, the more infrared absorption occurs (in much the same way that a sunglass lens absorbs visible light, alcohol absorbs infrared light). Thus the alcohol level of the driver is continuously monitored and calibrated on a scale. When it exceeds a particular limit the fuel supply is cutoff. If the device is removed also, the fuel supply will be automatically cut off or an alarm is sounded depending upon the requirement. This does not happen abruptly and special indicators are fixed at the back to avoid inconvenience to other drivers using the highway signals. Frame work for integration of sensors and control module in a scalable multi-agent system is provided .A SMS which contains the current GPS location of the vehicle is sent via a GSM module to the police control room to alert the police. The system is foolproof and the driver cannot tamper with it easily. Thus it provides an effective and cost effective solution for the problem of drunk driving in vehicles.
Abstract: The state and stability of hemoglobin adsorbed on the
glass surface was investigated using slab optical waveguide (SOWG)
spectroscopy. The peak position of the absorption band of hemoglobin
adsorbed on the glass surface was same as that of the hemoglobin in
solution. This result suggests that no significant denaturation occurred
by adsorption. The adsorption of hemoglobin is relatively strong that
the hemoglobin molecules even remained adsorbed after rinsing the
cell with buffer solution. The peak shift caused by the reduction of
adsorbed hemoglobin was also observed.
Abstract: The model of neural networks on the small-world
topology, with metric (local and random connectivity) is investigated.
The synaptic weights are random, driving the network towards a
chaotic state for the neural activity. An ordered macroscopic neuron
state is induced by a bias in the network connections. When the
connections are mainly local, the network emulates a block-like
structure. It is found that the topology and the bias compete to
influence the network to evolve into a global or a block activity
ordering, according to the initial conditions.
Abstract: Bumpers play an important role in preventing the
impact energy from being transferred to the automobile and
passengers. Saving the impact energy in the bumper to be released in
the environment reduces the damages of the automobile and
passengers.
The goal of this paper is to design a bumper with minimum weight
by employing the Glass Material Thermoplastic (GMT) materials.
This bumper either absorbs the impact energy with its deformation or
transfers it perpendicular to the impact direction.
To reach this aim, a mechanism is designed to convert about 80%
of the kinetic impact energy to the spring potential energy and
release it to the environment in the low impact velocity according to
American standard1. In addition, since the residual kinetic energy
will be damped with the infinitesimal elastic deformation of the
bumper elements, the passengers will not sense any impact. It should
be noted that in this paper, modeling, solving and result-s analysis
are done in CATIA, LS-DYNA and ANSYS V8.0 software
respectively.
Abstract: A solar powered air heating system using one ended evacuated tubes is experimentally investigated. A solar air heater containing forty evacuated tubes is used for heating purpose. The collector surface area is about 4.44 m2. The length and outer diameters of the outer glass tube and absorber tube are 1500, 47 and 37 mm, respectively. In this experimental setup, we have a header (heat exchanger) of square shape (190 mm x 190 mm). The length of header is 1500 mm. The header consists of a hollow pipe in the center whose diameter is 60 mm through which the air is made to flow. The experimental setup contains approximately 108 liters of water. Water is working as heat collecting medium which collects the solar heat falling on the tubes. This heat is delivered to the air flowing through the header pipe. This heat flow is due to natural convection and conduction. The outlet air temperature depends upon several factors along with air flow rate and solar radiation intensity. The study has been done for both up-flow and down-flow of air in header in similar weather conditions, at different flow rates. In the present investigations the study has been made to find the effect of intensity of solar radiations and flow rate of air on the out let temperature of the air with time and which flow is more efficient. The obtained results show that the system is highly effective for the heating in this region. Moreover, it has been observed that system is highly efficient for the particular flow rate of air. It was also observed that downflow configuration is more effective than up-flow condition at all flow rates due to lesser losses in down-flow. The results show that temperature differences of upper head and lower head, both of water and surface of pipes on the respective ends is lower in down-flow.
Abstract: Polymer-like organic thin films were deposited on both
aluminum alloy type 6061 and glass substrates at room temperature by
Plasma Enhanced Chemical Vapor Deposition (PECVD) methodusing
benzene and hexamethyldisiloxane (HMDSO) as precursor materials.
The surface and physical properties of plasma-polymerized organic
thin films were investigated at different r.f. powers. The effects of
benzene/argon ratio on the properties of plasma polymerized benzene
films were also investigated. It is found that using benzene alone
results in a non-coherent and non-adherent powdery deposited
material. The chemical structure and surface properties of the asgrown
plasma polymerized thin films were analyzed on glass
substrates with FTIR and contact angle measurements. FTIR spectra
of benzene deposited film indicated that the benzene rings are
preserved when increasing benzene ratio and/or decreasing r.f.
powers. FTIR spectra of HMDSO deposited films indicated an
increase of the hydrogen concentration and a decrease of the oxygen
concentration with the increase of r.f. power. The contact angle (θ) of
the films prepared from benzene was found to increase by about 43%
as benzene ratio increases from 10% to 20%. θ was then found to
decrease to the original value (51°) when the benzene ratio increases
to 100%. The contact angle, θ, for both benzene and HMDSO
deposited films were found to increase with r.f. power. This signifies
that the plasma polymerized organic films have substantially low
surface energy as the r.f power increases. The corrosion resistance of
aluminum alloy substrate both bare and covered with plasma
polymerized thin films was carried out by potentiodynamic
polarization measurements in standard 3.5 wt. % NaCl solution at
room temperature. The results indicate that the benzene and HMDSO
deposited films are suitable for protection of the aluminum substrate
against corrosion. The changes in the processing parameters seem to
have a strong influence on the film protective ability. Surface
roughness of films deposited on aluminum alloy substrate was
investigated using scanning electron microscopy (SEM). The SEM
images indicate that the surface roughness of benzene deposited films
increase with decreasing the benzene ratio. SEM images of benzene
and HMDSO deposited films indicate that the surface roughness
decreases with increasing r.f. power. Studying the above parameters
indicate that the films produced are suitable for specific practical
applications.
Abstract: Iran is one of the greatest producers of date in the
world. However due to lack of information about its viscoelastic
properties, much of the production downgraded during harvesting
and postharvesting processes. In this study the effect of temperature
and moisture content of product were investigated on stress
relaxation characteristics. Therefore, the freshly harvested date
(kabkab) at tamar stage were put in controlled environment chamber
to obtain different temperature levels (25, 35, 45, and 55 0C) and
moisture contents (8.5, 8.7, 9.2, 15.3, 20, 32.2 %d.b.). A texture
analyzer TAXT2 (Stable Microsystems, UK) was used to apply
uniaxial compression tests. A chamber capable to control temperature
was designed and fabricated around the plunger of texture analyzer to
control the temperature during the experiment. As a new approach a
CCD camera (A4tech, 30 fps) was mounted on a cylindrical glass
probe to scan and record contact area between date and disk.
Afterwards, pictures were analyzed using image processing toolbox
of Matlab software. Individual date fruit was uniaxially compressed
at speed of 1 mm/s. The constant strain of 30% of thickness of date
was applied to the horizontally oriented fruit. To select a suitable
model for describing stress relaxation of date, experimental data were
fitted with three famous stress relaxation models including the
generalized Maxwell, Nussinovitch, and Pelege. The constant in
mentioned model were determined and correlated with temperature
and moisture content of product using non-linear regression analysis.
It was found that Generalized Maxwell and Nussinovitch models
appropriately describe viscoelastic characteristics of date fruits as
compared to Peleg mode.
Abstract: Viscous heating becomes significant in the high speed
resin coating process of glass fibers for optical fiber manufacturing.
This study focuses on the coating resin flows inside the capillary
coating die of optical fiber coating applicator and they are numerically
simulated to examine the effects of viscous heating and subsequent
temperature increase in coating resin. Resin flows are driven by fast
moving glass fiber and the pressurization at the coating die inlet, while
the temperature dependent viscosity of liquid coating resin plays an
important role in the resin flow. It is found that the severe viscous
heating near the coating die wall profoundly alters the radial velocity
profiles and that the increase of final coating thickness by die
pressurization is amplified if viscous heating is present.
Abstract: An electrical apparatus for measuring moisture
content was developed by our laboratory and uses dependence of
electrical properties on water content in studied material. Error
analysis of the apparatus was run by measuring different volumes of
water in a simplified specimen, i.e. hollow plexiglass block, in order
to avoid as many side-effects as possible. Obtained data were
processed using both basic and advanced statistics and results were
compared with each other. The influence of water content on
accuracy of measured data was studied as well as the influence of
variation of apparatus' proper arrangement or factual methodics of its
usage. The overall coefficient of variation was 4%. There was no
trend found in results of error dependence on water content.
Comparison with current surveys led to a conclusion, that the studied
apparatus can be used for indirect measurement of water content in
porous materials, with expectable error and under known conditions.
Factual experiments with porous materials are not involved, but are
currently under investigation.
Abstract: This paper presents the results of thermo-mechanical
characterization of Glass/Epoxy composite specimens using Infrared
Thermography technique. The specimens used for the study were
fabricated in-house with three different lay-up sequences and tested
on a servo hydraulic machine under uni-axial loading. Infrared
Camera was used for on-line monitoring surface temperature changes
of composite specimens during tensile deformation.
Experimental results showed that thermomechanical
characteristics of each type of specimens were distinct. Temperature
was found to be decreasing linearly with increasing tensile stress in
the elastic region due to thermo-elastic effect. Yield point could be
observed by monitoring the change in temperature profile during
tensile testing and this value could be correlated with the results
obtained from stress-strain response. The extent of prior plastic
deformation in the post-yield region influenced the slopes of
temperature response during tensile loading. Partial unloading and
reloading of specimens post-yield results in change in slope in elastic
and plastic regions of composite specimens.
Abstract: A vast array of biological materials, especially algae have received increasing attention for heavy metal removal. Algae have been proven to be cheaper, more effective for the removal of metallic elements in aqueous solutions. A fresh water algal strain was isolated from Zoo Lake, Johannesburg, South Africa and identified as Desmodesmus sp. This paper investigates the efficacy of Desmodesmus sp.in removing heavy metals contaminating the Wonderfonteinspruit Catchment Area (WCA) water bodies. The biosorption data fitted the pseudo-second order and Langmuir isotherm models. The Langmuir maximum uptakes gave the sequence: Mn2+>Ni2+>Fe2+. The best results for kinetic study was obtained in concentration 120 ppm for Fe3+ and Mn2+, whilst for Ni2+ was at 20 ppm, which is about the same concentrations found in contaminated water in the WCA (Fe3+115 ppm, Mn2+ 121 ppm and Ni2+ 26.5 ppm).
Abstract: Langmuir–Blodgett (LB) films of polyaniline (PANI) grown onto ITO coated glass substrates were utilized for the fabrication of Uric acid biosensor for efficient detection of uric acid by immobilizing Uricase via EDC–NHS coupling. The modified electrodes were characterized by atomic force microscopy (AFM). The response characteristics after immobilization of uricase were studied using cyclic voltammetry and electrochemical impedance spectroscopy techniques. The uricase/PANI/ITO/glass bioelectrode studied by CV and EIS techniques revealed detection of uric acid in a wide range of 0.05 mM to 1.0 mM, covering the physiological range in blood. A low Michaelis–Menten constant (Km) of 0.21 mM indicates the higher affinity of immobilized Uricase towards its analyte (uric acid). The fabricated uric acid biosensor based on PANI LB films exhibits excellent sensitivity of 0.21 mA/mM with a response time of 4 s, good reproducibility, long shelf life (8 weeks) and high selectivity.
Abstract: Thermoplastic starch, polylactic acid glycerol and
maleic anhydride (MA) were compounded with natural
montmorillonite (MMT) through a twin screw extruder to investigate
the effects of different loading of MMT on structure, thermal and
absorption behavior of the nanocomposites. X-ray diffraction analysis
(XRD) showed that sample with MMT loading 4phr exhibited
exfoliated structure while sample that contained MMT 8 phr
exhibited intercalated structure. FESEM images showed big lump
when MMT loading was at 8 phr. The thermal properties were
characterized by using differential scanning calorimeter (DSC). The
results showed that MMT increased melting temperature and
crystallization temperature of matrix but reduction in glass transition
temperature was observed Meanwhile the addition of MMT has
improved the water barrier property. The nanosize MMT particle is
also able to block a tortuous pathway for water to enter the starch
chain, thus reducing the water uptake and improved the physical
barrier of nanocomposite.