Abstract: In this study, multiwall carbon nanotubes (MWNTs)
were modified with nitric acid chemically and by dielectric barrier
discharge (DBD) plasma in an oxygen-based atmosphere. Used
carbon nanotubes (CNTs) were prepared by chemical vapour
deposition (CVD) floating catalyst method. For removing amorphous
carbon and metal catalyst, MWNTs were exposed to dry air and
washed with hydrochloric acid. Heating purified CNTs under helium
atmosphere caused elimination of acidic functional groups. Fourier
transformed infrared spectroscopy (FTIR) shows formation of
oxygen containing groups such as C=O and COOH. Brunauer,
Emmett, Teller (BET) analysis revealed that functionalization causes
generation of defects on the sidewalls and opening of the ends of
CNTs. Results of temperature-programmed desorption (TPD) and gas
chromatography(GC) indicate that nitric acid treatment create more
acidic groups than plasma treatment.
Abstract: Malate dehydrogenase-glutamate oxaloacetate
aminotransferase (MDh-GOAT) enzyme complex (the EC) was
isolated and purified from wheat and rise, their some main physicchemical
properties were studied. Michael-s constants of the EC
MDh-GOAT to malate, glutamate and NAD were investigated. This
kinetic results show a high relationship to glutamate. Taking into
account important role of the the EC in catabolism of glutamate – the
central amino acid of a nitric exchange, there is a sharp necessity of
deeper studying of this enzyme complex. Therefore the basic purpose
of the work is studying the basic physical and chemical properties of
this enzyme complex discovered by us, which would be very
important for understanding the mechanisms of reaction catalyzed by
the EC.
Abstract: This is an application research presenting the
improvement of production quality using the six sigma solutions and
the analyses of benefit-cost ratio. The case of interest is the
production of tile-concrete. Such production has faced with the
problem of high nonconforming products from an inappropriate
surface coating and had low process capability based on the strength
property of tile. Surface coating and tile strength are the most critical
to quality of this product. The improvements followed five stages of
six sigma solutions. After the improvement, the production yield was
improved to 80% as target required and the defective products from
coating process was remarkably reduced from 29.40% to 4.09%. The
process capability based on the strength quality was increased from
0.87 to 1.08 as customer oriented. The improvement was able to save
the materials loss for 3.24 millions baht or 0.11 million dollars. The
benefits from the improvement were analyzed from (1) the reduction
of the numbers of non conforming tile using its factory price for
surface coating improvement and (2) the materials saved from the
increment of process capability. The benefit-cost ratio of overall
improvement was high as 7.03. It was non valuable investment in
define, measure, analyses and the initial of improve stages after that
it kept increasing. This was due to there were no benefits in define,
measure, and analyze stages of six sigma since these three stages
mainly determine the cause of problem and its effects rather than
improve the process. The benefit-cost ratio starts existing in the
improve stage and go on. Within each stage, the individual benefitcost
ratio was much higher than the accumulative one as there was an
accumulation of cost since the first stage of six sigma. The
consideration of the benefit-cost ratio during the improvement
project helps make decisions for cost saving of similar activities
during the improvement and for new project. In conclusion, the
determination of benefit-cost ratio behavior through out six sigma
implementation period provides the useful data for managing quality
improvement for the optimal effectiveness. This is the additional
outcome from the regular proceeding of six sigma.
Abstract: The mechanical and tribological properties in WC-Co
coatings are strongly affected by hardness and elasticity
specifications. The results revealed the effect of spraying distance on
microhardness and elasticity modulus of coatings. The metallurgical
studies have been made on coated samples using optical microscopy,
scanning electron microscopy (SEM).
Abstract: Recycling of aluminum alloys often decrease fluidity,
consequently influence the castability of the alloy. In this study, the
fluidity of Al-Zn alloys, such as the standard A713 alloy with and
without scrap addition has been investigated. The scrap added was
comprised of contaminated alloy turning chips. Fluidity
measurements were performed with double spiral fluidity test
consisting of gravity casting of double spirals in green sand moulds
with good reproducibility. The influence of recycled alloy on fluidity
has been compared with that of the virgin alloy and the results
showed that the fluidity decreased with the increase in recycled alloy
at minimum pouring temperatures. Interestingly, an appreciable
improvement in the fluidity was observed at maximum pouring
temperature, especially for coated spirals.
Abstract: The more recent satellite projects/programs makes
extensive usage of real – time embedded systems. 16 bit processors
which meet the Mil-Std-1750 standard architecture have been used in
on-board systems. Most of the Space Applications have been written
in ADA. From a futuristic point of view, 32 bit/ 64 bit processors are
needed in the area of spacecraft computing and therefore an effort is
desirable in the study and survey of 64 bit architectures for space
applications. This will also result in significant technology
development in terms of VLSI and software tools for ADA (as the
legacy code is in ADA).
There are several basic requirements for a special processor for
this purpose. They include Radiation Hardened (RadHard) devices,
very low power dissipation, compatibility with existing operational
systems, scalable architectures for higher computational needs,
reliability, higher memory and I/O bandwidth, predictability, realtime
operating system and manufacturability of such processors.
Further on, these may include selection of FPGA devices, selection
of EDA tool chains, design flow, partitioning of the design, pin
count, performance evaluation, timing analysis etc.
This project deals with a brief study of 32 and 64 bit processors
readily available in the market and designing/ fabricating a 64 bit
RISC processor named RISC MicroProcessor with added
functionalities of an extended double precision floating point unit
and a 32 bit signal processing unit acting as co-processors. In this
paper, we emphasize the ease and importance of using Open Core
(OpenSparc T1 Verilog RTL) and Open “Source" EDA tools such as
Icarus to develop FPGA based prototypes quickly. Commercial tools
such as Xilinx ISE for Synthesis are also used when appropriate.
Abstract: This paper presents the experimental results of
leakage current waveforms which appears on porcelain insulator
surface due to existence of artificial pollutants. The tests have been
done using the chemical compounds of NaCl, Na2SiO3, H2SO4, CaO,
Na2SO4, KCl, Al2SO4, MgSO4, FeCl3, and TiO2. The insulator
surface was coated with those compounds and dried. Then, it was
tested in the chamber where the high voltage was applied. Using
correspondence analysis, the result indicated that the fundamental
harmonic of leakage current was very close to the applied voltage
and third harmonic leakage current was close to the yielded leakage
current amplitude. The first harmonic power was correlated to first
harmonic amplitude of leakage current, and third harmonic power
was close to third harmonic one. The chemical compounds of H2SO4
and Na2SiO3 affected to the power factor of around 70%. Both are the
most conductive, due to the power factor drastically increase among
the chemical compounds.
Abstract: We report the size dependence of 1D superconductivity in ultrathin (10-130 nm) nanowires produced by coating suspended carbon nanotubes with a superconducting NbN thin film. The resistance-temperature characteristic curves for samples with ≧25 nm wire width show the superconducting transition. On the other hand, for the samples with 10-nm width, the superconducting transition is not exhibited owing to the quantum size effect. The differential resistance vs. current density characteristic curves show some peak, indicating that Josephson junctions are formed in nanowires. The presence of the Josephson junctions is well explained by the measurement of the magnetic field dependence of the critical current. These understanding allow for the further expansion of the potential application of NbN, which is utilized for single photon detectors and so on.
Abstract: Cardiovascular diseases, principally atherosclerosis, are responsible for 30% of world deaths. Atherosclerosis is due to the formation of plaque. The fatty plaque may be at risk of rupture, leading typically to stroke and heart attack. The plaque is usually associated with a high degree of lumen reduction, called a stenosis.It is increasingly recognized that the initiation and progression of disease and the occurrence of clinical events is a complex interplay between the local biomechanical environment and the local vascular biology. The aim of this study is to investigate the flow behavior through a stenosed artery. A physical experiment was performed using an artery model and blood analogue fluid. An axisymmetric model constructed consists of contraction and expansion region that follow a mathematical form of cosine function. A 30% diameter reduction was used in this study. The flow field was measured using particle image velocimetry (PIV). Spherical particles with 20μm diameter were seeded in a water-glycerol-NaCl mixture. Steady flow Reynolds numbers are 250. The area of interest is the region after the stenosis where the flow separation occurs. The velocity field was measured and the velocity gradient was investigated. There was high particle concentration in the recirculation zone. High velocity gradient formed immediately after the stenosis throat created a lift force that enhanced particle migration to the flow separation area.
Abstract: The mechanical properties of blends consisting of
plasticized poly(vinyl butyral) (PVB) and plasticized poly(vinyl
chloride) (PVC) are studied, in order to evaluate the possibility of
using recycled PVB waste derived from windshields. PVC was
plasticized with 38% of diisononyl phthalate (DINP), while PVB was
plasticized with 28% of triethylene glycol, bis(2-ethylhexanoate)
(3GO). The optimal process conditions for the PVB/PVC blend in 1:1
ratio were determined. Entropy was used in order to theoretically
predict the blends miscibility. The PVB content of each blend
composition used was ranging from zero to 100%. Tensile strength
and strain were tested. In addition, a comparison between recycled
and original PVB, used as constituents of the blend, was performed.
Abstract: This presentation reviews recent advances in superalloys and thermal barrier coating (TBC) for application in hot sections of energy-efficient gas-turbine engines. It has been reviewed that in the modern combined-cycle gas turbines (CCGT) applying single-crystal energy materials (SC superalloys) and thermal barrier coatings (TBC), and – in one design – closed-loop steam cooling, thermal efficiency can reach more than 60%. These technological advancements contribute to profitable and clean power generation with reduced emission. Alternatively, the use of advanced superalloys (e.g. GTD-111 superalloy, Allvac 718Plus superalloy) and advanced thermal barrier coatings (TBC) in modern gas-turbines has been shown to yield higher energy-efficiency in power generation.
Abstract: Coated tool inserts can be considered as the backbone
of machining processes due to their wear and heat resistance.
However, defects of coating can degrade the integrity of these inserts
and the number of these defects should be minimized or eliminated if
possible. Recently, the advancement of coating processes and
analytical tools open a new era for optimizing the coating tools.
First, an overview is given regarding coating technology for cutting
tool inserts. Testing techniques for coating layers properties, as well
as the various coating defects and their assessment are also surveyed.
Second, it is introduced an experimental approach to examine the
possible coating defects and flaws of worn multicoated carbide
inserts using two important techniques namely scanning electron
microscopy and atomic force microscopy. Finally, it is
recommended a simple procedure for investigating manufacturing
defects and flaws of worn inserts.
Abstract: Air emissions from waste treatment plants often
consist of a combination of Volatile Organic Compounds (VOCs)
and odors. Hydrogen sulfide is one of the major odorous gases
present in the waste emissions coming from municipal wastewater
treatment facilities. Hydrogen sulfide (H2S) is odorous, highly toxic
and flammable. Exposure to lower concentrations can result in eye
irritation, a sore throat and cough, shortness of breath, and fluid in
the lungs. Biofiltration has become a widely accepted technology for
treating air streams containing H2S. When compared with other nonbiological
technologies, biofilter is more cost-effective for treating large
volumes of air containing low concentrations of biodegradable compounds.
Optimization of biofilter media is essential for many reasons such as:
providing a higher surface area for biofilm growth, low pressure drop,
physical stability, and good moisture retention. In this work, a novel
biofilter media is developed and tested at a pumping station of a
municipality located in the United Arab Emirates (UAE). The
media is found to be very effective (>99%) in removing H2S
concentrations that are expected in pumping stations under steady
state and shock loading conditions.
Abstract: An ultrasound-assisted activation method for
electroless silver plating is presented in this study. When the
ultrasound was applied during the activation step, the amount of the Pd
species adsorbed on substrate surfaces was higher than that of sample
pretreated with a conventional activation process without ultrasound
irradiation. With this activation method, it was also shown that the
adsorbed Pd species with a size of about 5 nm were uniformly
distributed on the surfaces, thus a smooth and uniform coating on the
surfaces was obtained by subsequent electroless silver plating. The
samples after each step were characterized by AFM, XPS, FIB, and
SEM.
Abstract: Using data of listed Croatian firms from the Zagreb
Stock Exchange we analyze the relationship between firm ownership
(ownership concentration and type) and performance (ROA).
Empirical research was conducted for the period 2003-2010, yielding
with the total of 1,430 observations. Empirical findings based on
dynamic panel analysis indicate that ownership concentration
variable - CR4 is negatively related with performance, i.e. listed firms
with dispersed ownership perform better than firms with concentrated
ownership. Also, the research indicated that foreign controlled listed
firms perform better than domestically controlled firms. Majority
state owned firms perform worse than privately held firms but
dummy variable for privately controlled firms was not statistically
significant in the estimated panel model.
Abstract: Chemical detection is still a continuous challenge when
it comes to designing single-walled carbon nanotube (SWCNT)
sensors with high selectivity, especially in complex chemical
environments. A perfect example of such an environment would be in
thermally oxidized soybean oil. At elevated temperatures, oil oxidizes
through a series of chemical reactions which results in the formation of
monoacylglycerols, diacylglycerols, oxidized triacylglycerols, dimers,
trimers, polymers, free fatty acids, ketones, aldehydes, alcohols,
esters, and other minor products. In order to detect the rancidity of
oxidized soybean oil, carbon nanotube chemiresistor sensors have
been coated with polyethylenimine (PEI) to enhance the sensitivity
and selectivity. PEI functionalized SWCNTs are known to have a high
selectivity towards strong electron withdrawing molecules. The
sensors were very responsive to different oil oxidation levels and
furthermore, displayed a rapid recovery in ambient air without the
need of heating or UV exposure.
Abstract: Science and technology of ultrasonic is widely used in
recent years for industrial and medicinal application. The acoustical
properties of 2-mercapto substituted pyrimidines viz.,2- Mercapto-4-
(2’,4’ –dichloro phenyl) – 6-(2’ – hydroxyl -4’ –methyl-5’ –
chlorophenyl) pyrimidine and 2 –Mercapto – 4-(4’ –chloro phenyl) –
6-(2’ – hydroxyl -4’ –methyl-5’ –chlorophenyl) pyrimidine have been
investigated from the ultrasonic velocity and density measurements at
different concentration and different % in dioxane-water mixture at
305K. The adiabatic compressibility (βs), acoustic impedance (Z),
intermolecular free length (Lf), apparent molar volume(ϕv) and
relative association (RA) values have been calculated from the
experimental data of velocity and density measurement at
concentration range of 0.01- 0.000625 mol/lit and 70%,75% and 80%
dioxane water mixture. These above parameters are used to discuss
the structural and molecular interactions.
Abstract: Hot Mix Asphalt (HMA) is one of the most
commonest constructed asphalts in Iran and the quality control of
constructed roads with HMA have been always paid due attention by
researchers. The quality control of constructed roads with this
method is being usually carried out by measuring volumetric
parameters of HMA marshall samples. One of the important
parameters that has a critical role in changing these volumetric
parameters is “compaction temperature"; which as a result of its
changing, volumetric parameters of Marshall Samples and
subsequently constructed asphalt is encountered with variations. In
this study, considering the necessity of preservation of the
compaction temperature, the effect of various temperatures on Hot
Mix Asphalt (HMA) samples properties has been evaluated. As well,
to evaluate the effect of this parameter on different grading, two
different grading (Top coat index grading and binder index grading)
have been used and samples were compacted at 5 various
temperatures.
Abstract: A thin coating of hexamethyldisiloxane and subsequent O2-plasma treatment was performed on mirror-polished titanium in order to regulate the wide range of wettability including 106 and almost 0 degrees of contact angles. The adsorption behavior of
fibronectin and albumin in both individual and competitive mode,
and initial attachment of fibroblasts and osteoblasts were investigated.
Individually, fibronectin adsorption showed a biphasic inclination, whereas albumin showed greater adsorption to hydrophobic surfaces.
In competitive mode, in solution containing both fibronectin and albumin, fibronectin showed greater adsorption on hydrophilic
surfaces, whereas Alb predominantly adsorbed on hydrophobic
surfaces. Initial attachment of both cells increased with increase in
surface wettability, in particular, on super-hydrophilic surface, which
correlated well with fibronectin adsorption in competitive mode.
These results suggest that a cold plasma-surface modification enabled
to regulate the surface wettability, and fibronectin adsorption may be
responsible for increasing cell adhesion on hydrophilic surfaces in a
body fluid
Abstract: In this study, the dispersed model is used to predict
gas phase concentration, liquid drop concentration. The venturi
scrubber efficiency is calculated by gas phase concentration. The
modified model has been validated with available experimental data
of Johnstone, Field and Tasler for a range of throat gas velocities,
liquid to gas ratios and particle diameters and is used to study the
effect of some design parameters on collection efficiency.