Abstract: The Al-MoO3-P-CdTe-Al MOS sandwich structures
were fabricated by vacuum deposition method on cleaned glass
substrates. Capacitance versus voltage measurements were performed
at different frequencies and sweep rates of applied voltages for oxide
and semiconductor films of different thicknesses. In the negative
voltage region of the C-V curve a high differential capacitance of the
semiconductor was observed and at high frequencies (
Abstract: An efficient and green method for oxidation of thiols
to the corresponding disulfides is reported using ionic liquid
[HSO3N(C2H4OSO3H)3] in the presence of free nano-Fe2O3 at 60°C.
Ionic liquid is selective oxidant for S-S Coupling variety aliphatic
and aromatic of thiols to corresponding disulfide in the presence of
free nano-Fe2O3 as recoverable catalyst. Reaction has been performed
in methanol as an inexpensive solvent. This reaction is clean and easy
work-up with no side reaction.
Abstract: The exposure to outdoor air pollution causes lung
cancer and increases the risk of bladder cancer. Because air pollution
in urban areas is mainly caused by transportation, it is necessary to
evaluate pollutant exhaust emissions from vehicles during their realworld
use. Nevertheless their evaluation and reduction is a key
problem, especially in the cities, that account for more than 50% of
world population.
A particular attention was given to the slope variability along the
streets during each journey performed by the instrumented vehicle.
In this paper we dealt with the problem of describing a
quantitatively approach for the reconstruction of GPS coordinates and
altitude, in the context of correlation study between driving cycles /
emission / geographical location, during an experimental campaign
realized with some instrumented cars.
Finally the slope analysis can be correlated to the emission and
consumption values in a specific road position, and it could be
evaluated its influence on their behaviour.
Abstract: This paper deals with the issue of biomass and sorted
municipal waste gasification and cogeneration using hot-air turbo-set.
It brings description of designed pilot plant with electrical output 80
kWe. The generated gas is burned in secondary combustion chamber
located beyond the gas generator. Flue gas flows through the heat
exchanger where the compressed air is heated and consequently
brought to a micro turbine. Except description, this paper brings our
basic experiences from operating of pilot plant (operating parameters,
contributions, problems during operating, etc.). The principal
advantage of the given cycle is the fact that there is no contact
between the generated gas and the turbine. So there is no need for
costly and complicated gas cleaning which is the main source of
operating problems in direct use in combustion engines because the
content of impurities in the gas causes operation problems to the units
due to clogging and tarring of working surfaces of engines and
turbines, which may lead as far as serious damage to the equipment
under operation. Another merit is the compact container package
making installation of the facility easier or making it relatively more
mobile. We imagine, this solution of cogeneration from biomass or
waste can be suitable for small industrial or communal applications,
for low output cogeneration.
Abstract: In this study, first thermoplastic composite materials
/plates that have high ballistic impact resistance were produced. For
this purpose, the thermoplastic prepreg and the vacuum bagging
technique were used to produce a composite material. Thermoplastic
prepregs (resin-impregnated fiber) that are supplied ready to be used,
namely high-density polyethylene (HDPE) was chosen as matrix and
unidirectional glass fiber was used as reinforcement. In order to
compare the fiber configuration effect on mechanical properties,
unidirectional and biaxial prepregs were used. Then the
microstructural properties of the composites were investigated with
scanning electron microscopy (SEM) analysis. Impact properties of
the composites were examined by Charpy impact test and tensile
mechanical tests and then the effects of ultraviolet irradiation were
investigated on mechanical performance.
Abstract: With demand for primary energy continuously
growing, search for renewable and efficient energy sources has been
high on agenda of our society. One of the most promising energy
sources is biogas technology. Residues coming from dairy industry
and milk processing could be used in biogas production; however,
low efficiency and high cost impede wide application of such
technology. One of the main problems is management and conversion
of organic residues through the anaerobic digestion process which is
characterized by acidic environment due to the low whey pH (
Abstract: Composite materials have important assets compared
to traditional materials. They bring many functional advantages:
lightness, mechanical resistance and chemical, etc. In the present
study we examine the effect of a circular central notch and a precrack
on the tensile fracture of two woven composite materials. The tensile
tests were applied to a standardized specimen, notched and a
precarcked (orientation of the crack 0°, 45° and 90°). These tensile
tests were elaborated according to an experimental planning design of
the type 23.31 requiring 24 experiments with three repetitions. By the
analysis of regression, we obtained a mathematical model describing
the maximum load according to the influential parameters (hole
diameter, precrack length, angle of a precrack orientation). The
specimens precracked at 90° have a better behavior than those having
a precrack at 45° and still better than those having of the precracks
oriented at 0°. In addition the maximum load is inversely
proportional to the notch size.
Abstract: The paper presents the results of clusterization by
Kohonen self-organizing maps (SOM) applied for analysis of array of
Raman spectra of multi-component solutions of inorganic salts, for
determination of types of salts present in the solution. It is
demonstrated that use of SOM is a promising method for solution of
clusterization and classification problems in spectroscopy of multicomponent
objects, as attributing a pattern to some cluster may be
used for recognition of component composition of the object.
Abstract: The paper describes the experiments and the kinetic
parameters calculus of the gasoil hydrofining. They are presented
experimental results of gasoil hidrofining using Mo and promoted
with Ni on aluminum support catalyst. The authors have adapted a
kinetic model gasoil hydrofining. Using this proposed kinetic model
and the experimental data they have calculated the parameters of the
model. The numerical calculus is based on minimizing the difference
between the experimental sulf concentration and kinetic model
estimation.
Abstract: In this paper, strontium ferrite (SrO.6Fe2O3) was
synthesized by the sol-gel auto-combustion process. The thermal
behavior of powder obtained from self-propagating combustion of
initial gel was evaluated by simultaneous differential thermal analysis
(DTA) and thermo gravimetric (TG), from room temperature to
1200°C. The as-burnt powder was calcined at various temperatures
from 700-900°C to achieve the single-phase Sr-ferrite. Phase
composition, morphology and magnetic properties were investigated
using X-ray diffraction (XRD), transmission electron microscopy
(TEM) and vibrating sample magnetometry (VSM) techniques.
Results showed that the single-phase and nano-sized hexagonal
strontium ferrite particles were formed at calcination temperature of
800°C with crystallite size of 27 nm and coercivity of 6238 Oe.
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: Fly ash is an important waste, produced in thermal
power plants which causes very important environmental pollutions.
For this reason the usage and evaluation the fly ash in various areas
are very important. Nearly, 15 million tons/year of fly ash is
produced in Turkey. In this study, usage of fly ash with diatomite and
molasses for heavy metal (Cd) adsorption from wastewater is
investigated. The samples of Seyitomer region fly ash were analyzed
by X-ray fluorescence (XRF) and Scanning Electron Microscope
(SEM) then diatomite (0 and 1% in terms of fly ash, w/w) and
molasses (0-0.75 mL) were pelletized under 30 MPa of pressure for
the usage of cadmium (Cd) adsorption in wastewater. After the
adsorption process, samples of Seyitomer were analyzed using
Optical Emission Spectroscopy (ICP-OES). As a result, it is seen that
the usage of Seyitomer fly ash is proper for cadmium (Cd) adsorption
and an optimum adsorption yield with 52% is found at a compound
with Seyitomer fly ash (10 g), diatomite (0.5 g) and molasses (0.75
mL) at 2.5 h of reaction time, pH:4, 20ºC of reaction temperature and
300 rpm of stirring rate.
Abstract: The effect of various humidities on process yields and
degrees of crystallinity for spray-dried powders from spray drying of
lactose with humid air in a straight-through system have been
studied. It has been suggested by Williams–Landel–Ferry kinetics
(WLF) that a higher particle temperature and lower glass-transition
temperature would increase the crystallization rate of the particles
during the spray-drying process. Freshly humidified air produced by
a Buchi-B290 spray dryer as a humidifier attached to the main spray
dryer decreased the particle glass-transition temperature (Tg), while
allowing the particle temperature (Tp) to reach higher values by using
an insulated drying chamber. Differential scanning calorimetry
(DSC) and moisture sorption analysis were used to measure the
degree of crystallinity for the spray-dried lactose powders. The
results showed that higher Tp-Tg, as a result of applying humid air,
improved the process yield from 21 ± 4 to 26 ± 2% and crystallinity
of the particles by decreasing the latent heat of crystallization from
43 ± 1 to 30 ± 11 J/g and the sorption peak height from 7.3 ± 0.7% to
6 ± 0.7%.
Abstract: In the present study, M2 high speed steels were
fabricated by using electro-slag rapid remelting process. Carbide
structure was analysed and the fracture toughness and hardness were
also measured after austenitization treatment at 1190 and 1210oC
followed by tempering treatment at 535oC for billets with various
diameters from 16 to 60 mm. Electro-slag rapid remelting (ESRR)
process is an advanced ESR process combined by continuous casting
and successfully employed in this study to fabricate a sound M2 high
speed ingot. Three other kinds of commercial M2 high speed steels,
produced by traditional method, were also analysed for comparison.
Distribution and structure of eutectic carbides of the ESRR billet were
found to be comparable to those of commercial alloy and so was the
fracture toughness.
Abstract: Phase equilibria of AZ91D Mg alloys for
nonflammable use, containing Ca and Y, were carried out by using
FactSage® and FTLite database, which revealed that solid solution
treatment could be performed at temperatures from 400 to 450oC.
Solid solution treatment of AZ91D Mg alloy without Ca and Y was
successfully conducted at 420oC and supersaturated microstructure
with all beta phase resolved into matrix was obtained. In the case of
AZ91D Mg alloy with some Ca and Y; however, a little amount of
intermetallic particles were observed after solid solution treatment.
After solid solution treatment, each alloy was annealed at temperatures
of 180 and 200oC for time intervals from 1 min to 48 hrs and hardness
of each condition was measured by micro-Vickers method. Peak aging
conditions were deduced as at the temperature of 200oC for 10 hrs.
Abstract: This work presents the modelling and simulation of
saponification of ethyl acetate in the presence of sodium hydroxide in
a plug flow reactor using Aspen Plus simulation software. Plug flow
reactors are widely used in the industry due to the non-mixing
property. The use of plug flow reactors becomes significant when
there is a need for continuous large scale reaction or fast reaction.
Plug flow reactors have a high volumetric unit conversion as the
occurrence for side reactions is minimum. In this research Aspen Plus
V8.0 has been successfully used to simulate the plug flow reactor. In
order to simulate the process as accurately as possible HYSYS Peng-
Robinson EOS package was used as the property method. The results
obtained from the simulation were verified by the experiment carried
out in the EDIBON plug flow reactor module. The correlation
coefficient (r2) was 0.98 and it proved that simulation results
satisfactorily fit for the experimental model. The developed model
can be used as a guide for understanding the reaction kinetics of a
plug flow reactor.
Abstract: High temperature deformation behavior of cast
Fe-20Cr-5Al alloy has been investigated in this study by performing
tensile and compression tests at temperatures from 1100 to 1200oC.
Rectangular ingots of which the dimensions were 300×300×100 in
millimeter were cast using vacuum induction melting. Phase
equilibrium was calculated using the FactSage®, thermodynamic
software and database. Tensile strength of cast Fe-20Cr-5Al alloy was
4 MPa at 1200oC. With temperature decreased, tensile strength
increased rapidly and reached up to 13 MPa at 1100oC. Elongation
also increased from 18 to 80% with temperature decreased from
1200oC to 1100oC. Microstructure observation revealed that M23C6
carbide was precipitated along the grain boundary and within the
matrix.
Abstract: Because of high thermal efficiency and low CO2
emission, diesel engines are being used widely in many industrial
fields although it makes many PM and NOx which give both human
health and environment a negative effect. NOx regulations for diesel
engines, however, are being strengthened and it is impossible to meet
the emission standard without NOx reduction devices such as SCR
(Selective Catalytic Reduction), LNC (Lean NOx Catalyst), and LNT
(Lean NOx Trap). Among the NOx reduction devices, urea-SCR
system is known as the most stable and efficient method to solve the
problem of NOx emission. But this device has some issues associated
with the ammonia slip phenomenon which is occurred by shortage of
evaporation and thermolysis time, and that makes it difficult to achieve
uniform distribution of the injected urea in front of monolith.
Therefore, this study has focused on the mixing enhancement between
urea and exhaust gases to enhance the efficiency of the SCR catalyst
equipped in catalytic muffler by changing inlet gas temperature and
spray conditions to improve the spray uniformity of the urea water
solution. Finally, it can be found that various parameters such as inlet
gas temperature and injector and injection angles significantly affect
the evaporation and mixing of the urea water solution with exhaust
gases, and therefore, optimization of these parameters are required.
Abstract: In this research, copper borates are synthesized by the
reaction of copper sulfate pentahydrate (CuSO4.5H2O) and
tincalconite (Na2O4B7.10H2O). The experimental parameters are
selected as 80oC reaction temperature and 60 of reaction time. The
effect of mole ratio of CuSO4.5H2O to Na2O4B7.5H2O is studied. For
the identification analyses X-Ray Diffraction (XRD) and Fourier
Transform Infrared Spectroscopy (FT-IR) techniques are used. At the
end of the experiments, synthesized copper borate is matched with
the powder diffraction file of “00-001-0472” [Cu(BO2)2] and
characteristic vibrations between B and O atoms are seen. The proper
crystals are obtained at the mole ratio of 3:1. This study showed that
simplified synthesis process is suitable for the production of copper
borate minerals.
Abstract: The aim of work is to define the distribution density of
winding yarn on cylindrical and conical bobbins. It is known that
parallel winding gives greater density and more regular distribution,
but the unwinding of yarn is much more difficult for following
process.
The conical spool has an enormous advantage during unwinding
and may contain a large amount of yarns, but the density distribution
is not regular because of difference in diameters. The variation of
specific density over the reel height is explained generally by the
sudden change of winding speed due to direction movement variation
of yarn. We determined the conditions of uniform winding and
developed a calculate model to the change of the specific density of
winding wire over entire spool height.