Abstract: In the present research work we present the optical
emission studies of the Indium (In) – Tin (Sn) plasma produced by
the first (1064 nm) harmonic of an Nd: YAG nanosecond pulsed
laser. The experimentally observed line profiles of neutral Indium (In
I) and Tin (SnI) are used to extract the electron temperature (Te)
using the Boltzmann plot method. Whereas, the electron number
density (Ne) has been determined from the Stark broadening line
profile method. The Te is calculated by varying the distance from the
target surface along the line of propagation of plasma plume and also
by varying the laser irradiance. Beside we have studied the variation
of Ne as a function of laser irradiance as well as its variation with
distance from the target surface.
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: The knowledge of biodiesel density over large ranges
of temperature and pressure is important for predicting the behavior
of fuel injection and combustion systems in diesel engines, and for
the optimization of such systems. In this study, cottonseed oil was
transesterified into biodiesel and its density was measured at
temperatures between 288 K and 358 K and pressures between 0.1
MPa and 30 MPa, with expanded uncertainty estimated as ±1.6 kg⋅m-
3. Experimental pressure-volume-temperature (pVT) cottonseed data
was used along with literature data relative to other 18 biodiesels, in
order to build a database used to test the correlation of density with
temperarure and pressure using the Goharshadi–Morsali–Abbaspour
equation of state (GMA EoS). To our knowledge, this is the first that
density measurements are presented for cottonseed biodiesel under
such high pressures, and the GMA EoS used to model biodiesel
density. The new tested EoS allowed correlations within 0.2 kg·m-3
corresponding to average relative deviations within 0.02%. The built
database was used to develop and test a new full predictive model
derived from the observed linear relation between density and degree
of unsaturation (DU), which depended from biodiesel FAMEs
profile. The average density deviation of this method was only about
3 kg.m-3 within the temperature and pressure limits of application.
These results represent appreciable improvements in the context of
density prediction at high pressure when compared with other
equations of state.
Abstract: The theoretical approach is developed to describe the
change of drops in the atmosphere of own steam and buffer gas under
irradiation. It is shown that the irradiation influences on size of stable
droplet and on the conditions under which the droplet exists. Under
irradiation the change of drop becomes more complex: the not
monotone and periodical change of size of drop becomes possible.
All possible solutions are represented by means of phase portrait. It is
found all qualitatively different phase portraits as function of critical
parameters: rate generation of clusters and substance density.
Abstract: Boron-gypsum is a waste which occurs in the boric
acid production process. In this study, the boron content of this waste
is evaluated for the use in synthesis of magnesium borates and such
evaluation of this kind of waste is useful more than storage or
disposal. Magnesium borates, which are a sub-class of boron
minerals, are useful additive materials for the industries due to their
remarkable thermal and mechanical properties. Magnesium borates
were obtained hydrothermally at different temperatures. Novelty of
this study is the search of the solution density effects to magnesium
borate synthesis process for the increasing the possibility of borongypsum
usage as a raw material. After the synthesis process, products
are subjected to XRD and FT-IR to identify and characterize their
crystal structure, respectively.
Abstract: A phase diagram of the Ag2SO4 - CaSO4 (Silver sulphate – Calcium Sulphate) binaries system using conductivity, XRD (X-Ray Diffraction Technique) and DTA (Differential Thermal Analysis) data is constructed. The eutectic reaction (liquid -» a-Ag2SO4 + CaSO4) is observed at 10 mole% CaSO4 and 645°C. Room temperature solid solubility limit up to 5.27 mole % of Ca 2+ in Ag2SO4 is set using X-ray powder diffraction and scanning electron microscopy results. All compositions beyond this limit are two-phase mixtures below and above the transition temperature (≈ 416°C). The bulk conductivity, obtained following complex impedance spectroscopy, is found decreasing with increase in CaSO4 content. Amongst other binary compositions, the 80AgSO4-20CaSO4 gave improved sinterability/packing density.
Abstract: Aluminum Matrix Composites reinforced with
nanocrystalline Ni3Al carbon-coated intermetallic particles, were
synthesized by powder metallurgy. Powder mixture of aluminum
with 0.5-volume fraction of reinforcement particles was compacted
by spark plasma sintering (SPS) technique and the compared with
conventional sintering process. The better results for SPS technique
were obtained in 520ºC-5kN-3min.The hardness (70.5±8 HV) and the
elastic modulus (95 GPa) were evaluated in function of sintering
conditions for SPS technique; it was found that the incorporation of
these kind of reinforcement particles in aluminum matrix improve its
mechanical properties. The densities were about 94% and 97% of the
theoretical density. The carbon coating avoided the interfacial
reaction between matrix-particle at high temperature (520°C) without
show composition change either intermetallic dissolution.
Abstract: Forest areas are particularly susceptible to fires, which are often manmade. One of the most fire affected forest regions in the world is the Mediterranean. Libya, in the Mediterranean region, has soils that are considered to be arid except in a small area called Aljabal Alakhdar (Green mountain), which is the geographic area covered by this study. Like other forests in the Mediterranean it has suffered extreme degradation. This is mainly due to people removing fire wood, or sometimes converting forested areas to agricultural use, as well as fires which may alter several soil chemical and physical properties. The purpose of this study was to evaluate the effects of fires on the physical properties of soil of Aljabal Alakhdar forest in the north-east of Libya. The physical properties of soil following fire in two geographic areas have been determined, with those subjected to the fire compared to those in adjacent unburned areas in one coastal and one mountain site. Physical properties studied were: soil particle size (soil texture), soil water content, soil porosity and soil particle density. For the first time in Libyan soils, the effect of burning on the magnetic susceptibility properties of soils was also tested. The results showed that the soils in both study sites, irrespective of burning or depth fell into the category of a silt loam texture, low water content, homogeneity of porosity of the soil profiles, relatively high soil particle density values and there is a much greater value of the soil magnetic susceptibility in the top layer from both sites except for the soil water content and magnetic susceptibility, fire has not had a clear effect on the soils’ physical properties.
Abstract: Rogowski coils are increasingly used for measurement
of AC and transient electric currents. Mostly used Rogowski coils
now are with circular or rectangular cores. In order to increase the
sensitivity of the measurement of Rogowski coil and perform smooth
wire winding, this paper studies the effect of increasing the mutual
inductance in order to increase the coil sensitivity by presenting the
calculation and simulation of a Rogowski coil with equilateral
hexagonal shaped core and comparing the resulted mutual inductance
with commonly used core shapes.
Abstract: Radiation shielding is an obstacle in long duration space exploration. Boron Nitride Nanotubes (BNNTs) have attracted attention as an additive to radiation shielding material due to B10’s large neutron capture cross section. The B10 has an effective neutron capture cross section suitable for low energy neutrons ranging from 10-5 to 104 eV and hydrogen is effective at slowing down high energy neutrons. Hydrogenated BNNTs are potentially an ideal nanofiller for radiation shielding composites. We use Molecular Dynamics (MD) Simulation via Material Studios Accelrys 6.0 to model the Young’s Modulus of Hydrogenated BNNTs. An extrapolation technique was employed to determine the Young’s Modulus due to the deformation of the nanostructure at its theoretical density. A linear regression was used to extrapolate the data to the theoretical density of 2.62g/cm3. Simulation data shows that the hydrogenated BNNTs will experience a 11% decrease in the Young’s Modulus for (6,6) BNNTs and 8.5% decrease for (8,8) BNNTs compared to non-hydrogenated BNNT’s. Hydrogenated BNNTs are a viable option as a nanofiller for radiation shielding nanocomposite materials for long range and long duration space exploration.
Abstract: Cubic equations of state like Redlich–Kwong (RK)
EOS have been proved to be very reliable tools in the prediction of
phase behavior. Despite their good performance in compositional
calculations, they usually suffer from weaknesses in the predictions
of saturated liquid density. In this research, RK equation was
modified. The result of this study show that modified equation has
good agreement with experimental data.
Abstract: The suitability of Newsprint and Kraft papers for the production of cement bonded ceiling board was investigated. Sample boards were produced from newsprint paper (100%), mixture of newsprint and Kraft paper (50:50) and Kraft paper (100%) at 1:1, 2:1 and 3:1 cement/paper mixing ratio respectively with 3% additive concentration of calcium chloride (CaCl2). Density, flexural and thickness swelling properties of the boards were investigated. The effects of paper type and mixing ratio on the physical and mechanical properties were also examined. The bending properties of the board which include Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) increased linearly with increase in density. Modulus of rupture of boards increased as the density and mixing ratio increased. The thickness swelling property for the two paper types decreased as the board density and mixing ratio increased. Boards made from Kraft paper recorded higher strength values than the ones made from recycled newsprint paper while the mixture of kraft and newsprint papers had the best surface finish. The result of the study will help in managing the large quality of waste from paper converting/carton industry and that the ceiling boards produced could be installed with clout nails or used with suspended ceiling fittings.
Abstract: Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and crop yield. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1 - to assess the effects of tillage systems (Conventional System (CS), Minimum Tillage (MT), No-Tillage (NT)) on soil compaction, soil temperature, soil moisture and soil respiration and 2- to establish the effect of the changes on the production of wheat, maize and soybean. Five treatments were installed: CS-plough; MT-paraplow, chisel, rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this; soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15cm of soil depth and increased the soil temperature by 0.5-2.20C. Water dynamics and soil temperature showed no differences on the effect of crop yields. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the four conservation tillage measures decreased soil respiration, with the best effects of no-tillage. Although wheat production at MT and NT applications, had no significant differences soybean production was significantly affected from MT and NT applications. The differences in crop yields are recorded at maize and can be a direct consequence of loosening, mineralization and intensive mobilization of soil fertility.
Abstract: Remote sensing image processing, spatial data analysis through GIS approach, and analytical hierarchy process were introduced in this study for assessing the vulnerability area and inundation area due to tsunami hazard in the area of Rikuzentakata, Iwate Prefecture, Japan. Appropriate input parameters were derived from GSI DEM data, ALOS AVNIR-2, and field data. We used the parameters of elevation, slope, shoreline distance, and vegetation density. Five classes of vulnerability were defined and weighted via pairwise comparison matrix. The assessment results described that 14.35km2 of the study area was under tsunami vulnerability zone. Inundation areas are those of high and slightly high vulnerability. The farthest area reached by a tsunami was about 7.50km from the shoreline and shows that rivers act as flooding strips that transport tsunami waves into the hinterland. This study can be used for determining a priority for land-use planning in the scope of tsunami hazard risk management.
Abstract: The porous silicon (PS), formed from the anodization
of a p+ type substrate silicon, consists of a network organized in a
pseudo-column as structure of multiple side ramifications. Structural
micro-topology can be interpreted as the fraction of the interconnected
solid phase contributing to thermal transport. The
reduction of dimensions of silicon of each nanocristallite during the
oxidation induced a reduction in thermal conductivity. Integration of
thermal sensors in the Microsystems silicon requires an effective
insulation of the sensor element. Indeed, the low thermal conductivity
of PS consists in a very promising way in the fabrication of integrated
thermal Microsystems.In this work we are interesting in the
measurements of thermal conductivity (on the surface and in depth)
of PS by the micro-Raman spectroscopy. The thermal conductivity is
studied according to the parameters of anodization (initial doping and
current density. We also, determine porosity of samples by
spectroellipsometry.
Abstract: The African Great Lakes Region refers to the zone
around lakes Victoria, Tanganyika, Albert, Edward, Kivu, and
Malawi. The main source of electricity in this region is hydropower
whose systems are generally characterized by relatively weak,
isolated power schemes, poor maintenance and technical deficiencies
with limited electricity infrastructures. Most of the hydro sources are
rain fed, and as such there is normally a deficiency of water during
the dry seasons and extended droughts. In such calamities fossil fuels
sources, in particular petroleum products and natural gas, are
normally used to rescue the situation but apart from them being nonrenewable,
they also release huge amount of green house gases to our
environment which in turn accelerates the global warming that has at
present reached an amazing stage. Wind power is ample, renewable,
widely distributed, clean, and free energy source that does not
consume or pollute water. Wind generated electricity is one of the
most practical and commercially viable option for grid quality and
utility scale electricity production. However, the main shortcoming
associated with electric wind power generation is fluctuation in its
output both in space and time. Before making a decision to establish
a wind park at a site, the wind speed features there should therefore
be known thoroughly as well as local demand or transmission
capacity. The main objective of this paper is to utilise monthly
average wind speed data collected from one prospective site within
the African Great Lakes Region to demonstrate that the available
wind power there is high enough to generate electricity. The mean
monthly values were calculated from records gathered on hourly
basis for a period of 5 years (2001 to 2005) from a site in Tanzania.
The documentations that were collected at a height of 2 m were
projected to a height of 50 m which is the standard hub height of
wind turbines. The overall monthly average wind speed was found to
be 12.11 m/s whereas June to November was established to be the
windy season as the wind speed during the session is above the
overall monthly wind speed. The available wind power density
corresponding to the overall mean monthly wind speed was evaluated
to be 1072 W/m2, a potential that is worthwhile harvesting for the
purpose of electric generation.
Abstract: Microbial-induced calcite precipitation (MICP) is a
relatively green and sustainable soil improvement technique. It
utilizes biochemical process that exists naturally in soil to improve
engineering properties of soils. The calcite precipitation process is
uplifted by the mean of injecting higher concentration of urease
positive bacteria and reagents into the soil. The main objective of this
paper is to provide an overview of the factors affecting the MICP in
soil. Several factors were identified including nutrients, bacteria type,
geometric compatibility of bacteria, bacteria cell concentration,
fixation and distribution of bacteria in soil, temperature, reagents
concentration, pH, and injection method. These factors were found to
be essential for promoting successful MICP soil treatment.
Furthermore, a preliminary laboratory test was carried out to
investigate the potential application of the technique in improving the
shear strength and impermeability of a residual soil specimen. The
results showed that both shear strength and impermeability of
residual soil improved significantly upon MICP treatment. The
improvement increased with increasing soil density.
Abstract: Preparation of size controlled nano-particles of silver catalyst on carbon substrate from e-waste has been investigated. Chemical route was developed by extraction of the metals available in nitric acid followed by treatment with hydrofluoric acid. Silver metal particles deposited with an average size 4-10 nm. A stabilizer concentration of 10- 40 g/l was used. The average size of the prepared silver decreased with increase of the anode current density. Size uniformity of the silver nano-particles was improved distinctly at higher current density no more than 20mA... Grain size increased with EK time whereby aggregation of particles was observed after 6 h of reaction.. The chemical method involves adsorption of silver nitrate on the carbon substrate. Adsorbed silver ions were directly reduced to metal particles using hydrazine hydrate. Another alternative method is by treatment with ammonia followed by heating the carbon loaded-silver hydroxide at 980°C. The product was characterized with the help of XRD, XRF, ICP, SEM and TEM techniques.
Abstract: In the current decade, wireless sensor networks are
emerging as a peculiar multi-disciplinary research area. By this
way, energy efficiency is one of the fundamental research themes
in the design of Medium Access Control (MAC) protocols for
wireless sensor networks. Thus, in order to optimize the energy
consumption in these networks, a variety of MAC protocols are
available in the literature. These schemes were commonly evaluated
under simple network density and a few results are published on
their robustness in realistic network-s size. We, in this paper, provide
an analytical study aiming to highlight the energy waste sources in
wireless sensor networks. Then, we experiment three energy efficient
hybrid CSMA/CA based MAC protocols optimized for wireless
sensor networks: Sensor-MAC (SMAC), Time-out MAC (TMAC)
and Traffic aware Energy Efficient MAC (TEEM). We investigate
these protocols with different network densities in order to discuss
the end-to-end performances of these schemes (i.e. in terms of energy
efficiency, delay and throughput). Through Network Simulator (NS-
2) implementations, we explore the behaviors of these protocols with
respect to the network density. In fact, this study may help the multihops
sensor networks designers to design or select the MAC layer
which matches better their applications aims.
Abstract: Sesame is one of the oldest and most important oil
crops as main crop and second crop agriculture. This study was
carried out to determine the effects of different inter- and intra-row
spacings on the yield and yield components on second crop sesame;
was set up in Antalya West Mediterranean Agricultural Research
Institue in 2009. Muganlı 57 sesame cultivar was used as plant
material. The field experiment was set up in a split plot design and
row spacings (30, 40, 50, 60 and 70 cm) were assigned to the main
plots and and intra-row spacings (5, 10, 20 and 30 cm) were assigned
to the subplots. Seed yield, oil ratio, oil yield, protein ratio and
protein yield were investigated. In general, wided inter row spacings
and intra-row spacings, resulted in decreased seed yield, oil yield and
protein yield. The highest seed yield, oil yield and protein yield
(respectively, 1115.0 kg ha-1, 551.3 kg ha-1, 224.7 kg ha-1) were
obtained from 30x5 cm plant density while the lowest seed yield, oil
yield and protein yield (respectively, 677.0 kg ha-1, 327.0 kg ha-1,
130.0 kg ha-1) were recorded from 70x30 cm plant density. As a
result, in terms of oil yield for second crop sesame agriculture, 30 cm
row spacing, and 5 cm intra row spacing are the most suitable plant
densities.