Abstract: This paper presents a numerical analysis of the
performance of a three-bladed Darrieus vertical-axis wind turbine
based on the DU91-W2-250 airfoil. A complete campaign of 2-D
simulations, performed for several values of tip speed ratio and based
on RANS unsteady calculations, has been performed to obtain the
rotor torque and power curves. Rotor performances have been
compared with the results of a previous work based on the use of the
NACA 0021 airfoil. Both the power coefficient and the torque
coefficient have been determined as a function of the tip speed ratio.
The flow field around rotor blades has also been analyzed. As a final
result, the performance of the DU airfoil based rotor appears to be
lower than the one based on the NACA 0021 blade section. This
behavior could be due to the higher stall characteristics of the NACA
profile, being the separation zone at the trailing edge more extended
for the DU airfoil.
Abstract: Infrared focal plane arrays (IRFPA) sensors, due to
their high sensitivity, high frame frequency and simple structure, have
become the most prominently used detectors in military applications.
However, they suffer from a common problem called the fixed pattern
noise (FPN), which severely degrades image quality and limits the
infrared imaging applications. Therefore, it is necessary to perform
non-uniformity correction (NUC) on IR image. The algorithms of
non-uniformity correction are classified into two main categories, the
calibration-based and scene-based algorithms. There exist some
shortcomings in both algorithms, hence a novel non-uniformity
correction algorithm based on non-linear fit is proposed, which
combines the advantages of the two algorithms. Experimental results
show that the proposed algorithm acquires a good effect of NUC with
a lower non-uniformity ratio.
Abstract: Automatic determination of blood in less bright or
noisy capsule endoscopic images is difficult due to low S/N ratio.
Especially it may not be accurate to analyze these images due to the
influence of external disturbance. Therefore, we proposed detection
methods that are not dependent only on color bands. In locating
bleeding regions, the identification of object outlines in the frame and
features of their local colors were taken into consideration. The results
showed that the capability of detecting bleeding was much improved.
Abstract: Lignocellulosic materials are new targeted source to
produce second generation biofuels like biobutanol. However, this
process is significantly resisted by the native structure of biomass.
Therefore, pretreatment process is always essential to remove
hemicelluloses and lignin prior to the enzymatic hydrolysis.
The goals of pretreatment are removing hemicelluloses and
lignin, increasing biomass porosity, and increasing the enzyme
accessibility. The main goal of this research is to study the important
variables such as pretreatment temperature and time, which can give
the highest total sugar yield in pretreatment step by using dilute
phosphoric acid. After pretreatment, the highest total sugar yield of
13.61 g/L was obtained under an optimal condition at 140°C for 10
min of pretreatment time by using 1.75% (w/w) H3PO4 and at 15:1
liquid to solid ratio. The total sugar yield of two-stage process
(pretreatment+enzymatic hydrolysis) of 27.38 g/L was obtained.
Abstract: In this paper we are interested in Moufang-Klingenberg
planesM(A) defined over a local alternative ring A of dual numbers.
We show that a collineation of M(A) preserve cross-ratio. Also, we
obtain some results about harmonic points.
Abstract: While compressing text files is useful, compressing
still image files is almost a necessity. A typical image takes up much
more storage than a typical text message and without compression
images would be extremely clumsy to store and distribute. The
amount of information required to store pictures on modern
computers is quite large in relation to the amount of bandwidth
commonly available to transmit them over the Internet and
applications. Image compression addresses the problem of reducing
the amount of data required to represent a digital image. Performance
of any image compression method can be evaluated by measuring the
root-mean-square-error & peak signal to noise ratio. The method of
image compression that will be analyzed in this paper is based on the
lossy JPEG image compression technique, the most popular
compression technique for color images. JPEG compression is able to
greatly reduce file size with minimal image degradation by throwing
away the least “important" information. In JPEG, both color
components are downsampled simultaneously, but in this paper we
will compare the results when the compression is done by
downsampling the single chroma part. In this paper we will
demonstrate more compression ratio is achieved when the
chrominance blue is downsampled as compared to downsampling the
chrominance red in JPEG compression. But the peak signal to noise
ratio is more when the chrominance red is downsampled as compared
to downsampling the chrominance blue in JPEG compression. In
particular we will use the hats.jpg as a demonstration of JPEG
compression using low pass filter and demonstrate that the image is
compressed with barely any visual differences with both methods.
Abstract: Turkey has 72 % of total world boron reserves on the
basis of B2O3.Borates that is a refined form of boron minerals have a
wide range of applications. Zinc borates can be used as multifunctional
synergistic additives. The most important properties are
low solubility in water and high dehydration temperature. Zinc
borates dehydrate above 290°C and anhydrous zinc borate has
thermal resistance about 400°C. Zinc borates can be synthesized
using several methods such as hydrothermal and solid-state
processes. In this study, the solid-state method was applied between
500 and 800°C using the starting materials of ZnO and H3BO3 with
1:4 mole ratio. The reaction time was determined as 4 hours after
some preliminary experiments. After the synthesis, the crystal
structure and the morphology of the products were examined by XRay
Diffraction (XRD), Fourier Transform Infrared Spectroscopy
(FT-IR) and Raman Spectrometer. As a result the form of ZnB4O7
was synthesized with the highest crystal score at 800°C.
Abstract: This paper presents an investigation of the power
penalties imposed by four-wave mixing (FWM) on G.652 (Single-
Mode Fiber - SMF), G.653 (Dispersion-Shifted Fiber - DSF), and
G.655 (Non-Zero Dispersion-Shifted Fiber - NZDSF) compliant
fibers, considering the DWDM grids suggested by the ITU-T
Recommendations G.692, and G.694.1, with uniform channel
spacing of 100, 50, 25, and 12.5 GHz. The mathematical/numerical
model assumes undepleted pumping, and shows very clearly the
deleterious effect of FWM on the performance of DWDM systems,
measured by the signal-to-noise ratio (SNR). The results make it
evident that non-uniform channel spacing is practically mandatory
for WDM systems based on DSF fibers.
Abstract: A high performance computer includes a fast
processor and millions bytes of memory. During the data processing,
huge amount of information are shuffled between the memory and
processor. Because of its small size and its effectiveness speed, cache
has become a common feature of high performance computers.
Enhancing cache performance proved to be essential in the speed up
of cache-based computers. Most enhancement approaches can be
classified as either software based or hardware controlled. The
performance of the cache is quantified in terms of hit ratio or miss
ratio. In this paper, we are optimizing the cache performance based
on enhancing the cache hit ratio. The optimum cache performance is
obtained by focusing on the cache hardware modification in the way
to make a quick rejection to the missed line's tags from the hit-or
miss comparison stage, and thus a low hit time for the wanted line in
the cache is achieved. In the proposed technique which we called
Even- Odd Tabulation (EOT), the cache lines come from the main
memory into cache are classified in two types; even line's tags and
odd line's tags depending on their Least Significant Bit (LSB). This
division is exploited by EOT technique to reject the miss match line's
tags in very low time compared to the time spent by the main
comparator in the cache, giving an optimum hitting time for the
wanted cache line. The high performance of EOT technique against
the familiar mapping technique FAM is shown in the simulated
results.
Abstract: This paper presents the experimental results of a
single cylinder Enfield engine using an electronically controlled fuel
injection system which was developed to carry out exhaustive tests
using neat CNG, and mixtures of hydrogen in compressed natural gas
(HCNG) as 0, 5, 10, 15 and 20% by energy. Experiments were
performed at 2000 and 2400 rpm with wide open throttle and varying
the equivalence ratio. Hydrogen which has fast burning rate, when
added to compressed natural gas, enhances its flame propagation rate.
The emissions of HC, CO, decreased with increasing percentage of
hydrogen but NOx was found to increase. The results indicated a
marked improvement in the brake thermal efficiency with the
increase in percentage of hydrogen added. The improved thermal
efficiency was clearly observed to be more in lean region as
compared to rich region. This study is expected to reduce vehicular
emissions along with increase in thermal efficiency and thus help in
reduction of further environmental degradation.
Abstract: This paper presents an advance in monitoring and
process control of surface roughness in CNC machine for the turning
and milling processes. An integration of the in-process monitoring
and process control of the surface roughness is proposed and
developed during the machining process by using the cutting force
ratio. The previously developed surface roughness models for turning
and milling processes of the author are adopted to predict the inprocess
surface roughness, which consist of the cutting speed, the
feed rate, the tool nose radius, the depth of cut, the rake angle, and
the cutting force ratio. The cutting force ratios obtained from the
turning and the milling are utilized to estimate the in-process surface
roughness. The dynamometers are installed on the tool turret of CNC
turning machine and the table of 5-axis machining center to monitor
the cutting forces. The in-process control of the surface roughness
has been developed and proposed to control the predicted surface
roughness. It has been proved by the cutting tests that the proposed
integration system of the in-process monitoring and the process
control can be used to check the surface roughness during the cutting
by utilizing the cutting force ratio.
Abstract: Extraction of lactic acid from aqueous solution using n-butanol as an extractant was studied. Effect of mixing time, pH of the aqueous solution, initial lactic acid concentration, and volume ratio between the organic and the aqueous phase were investigated. Distribution coefficient and degree of lactic acid extraction was found to increase when the pH of aqueous solution was decreased. The pH Effect was substantially pronounced at pH of the aqueous solution less than 1. Initial lactic acid concentration and organic-toaqueous volume ratio appeared to have positive effect on the distribution coefficient and the degree of extraction. Due to the nature of n-butanol that is partially miscible in water, incorporation of aqueous solution into organic phase was observed in the extraction with large organic-to-aqueous volume ratio.
Abstract: The major problem that wireless communication
systems undergo is multipath fading caused by scattering of the
transmitted signal. However, we can treat multipath propagation as
multiple channels between the transmitter and receiver to improve
the signal-to-scattering-noise ratio. While using Single Input
Multiple Output (SIMO) systems, the diversity receivers extract
multiple signal branches or copies of the same signal received from
different channels and apply gain combining schemes such as Root
Mean Square Gain Combining (RMSGC). RMSGC asymptotically
yields an identical performance to that of the theoretically optimal
Maximum Ratio Combining (MRC) for values of mean Signal-to-
Noise-Ratio (SNR) above a certain threshold value without the need
for SNR estimation. This paper introduces an improvement of
RMSGC using two different issues. We found that post-detection and
de-noising the received signals improve the performance of RMSGC
and lower the threshold SNR.
Abstract: Electrical Discharge Machine (EDM) is especially
used for the manufacturing of 3-D complex geometry and hard
material parts that are extremely difficult-to-machine by conventional
machining processes. In this paper authors review the research work
carried out in the development of die-sinking EDM within the past
decades for the improvement of machining characteristics such as
Material Removal Rate, Surface Roughness and Tool Wear Ratio. In
this review various techniques reported by EDM researchers for
improving the machining characteristics have been categorized as
process parameters optimization, multi spark technique, powder
mixed EDM, servo control system and pulse discriminating. At the
end, flexible machine controller is suggested for Die Sinking EDM to
enhance the machining characteristics and to achieve high-level
automation. Thus, die sinking EDM can be integrated with Computer
Integrated Manufacturing environment as a need of agile
manufacturing systems.
Abstract: In this paper, a Biochemical Methane Potential (BMP)
test provides a measure of the energy production potential from codigestion
between the frozen seafood wastewater and the decanter
cake. The experiments were conducted in laboratory-scale. The
suitable ratio of the frozen seafood wastewater and the decanter cake
was observed in the BMP test. The ratio of the co-digestion between
the frozen seafood wastewater and the decanter cake has impacts on
the biogas production and energy production potential. The best
performance for energy production potential using BMP test
observed from the 180 ml of the frozen seafood wastewater and 10 g
of the decanter cake ratio. This ratio provided the maximum methane
production at 0.351 l CH4/g TCODremoval. The removal efficiencies
are 76.18%, 83.55%, 43.16% and 56.76% at TCOD, SCOD, TS and
VS, respectively. The result can be concluded that the decanter cake
can improve the energy production potential of the frozen seafood
wastewater. The energy provides from co-digestion between frozen
seafood wastewater and decanter cake approximately 19x109
MJ/year in Thailand.
Abstract: In this paper the problem of estimating the time delay
between two spatially separated noisy sinusoidal signals by system
identification modeling is addressed. The system is assumed to be
perturbed by both input and output additive white Gaussian noise. The
presence of input noise introduces bias in the time delay estimates.
Normally the solution requires a priori knowledge of the input-output
noise variance ratio. We utilize the cascade of a self-tuned filter with
the time delay estimator, thus making the delay estimates robust to
input noise. Simulation results are presented to confirm the superiority
of the proposed approach at low input signal-to-noise ratios.
Abstract: Ovshinsky initiated scientific research in the field of
amorphous and disordered materials that continues to this day. The
Ovshinsky Effect where the resistance of thin GST films is
significantly reduced upon the application of low voltage is of
fundamental importance in phase-change - random access memory
(PC-RAM) devices.GST stands for GdSbTe chalcogenide type
glasses.However, the Ovshinsky Effect is not without controversy.
Ovshinsky thought the resistance of GST films is reduced by the
redistribution of charge carriers; whereas, others at that time including
many PC-RAM researchers today argue that the GST resistance
changes because the GST amorphous state is transformed to the
crystalline state by melting, the heat supplied by external heaters. In
this controversy, quantum mechanics (QM) asserts the heat capacity of
GST films vanishes, and therefore melting cannot occur as the heat
supplied cannot be conserved by an increase in GST film
temperature.By precluding melting, QM re-opens the controversy
between the melting and charge carrier mechanisms. Supporting
analysis is presented to show that instead of increasing GST film
temperature, conservation proceeds by the QED induced creation of
photons within the GST film, the QED photons confined by TIR. QED
stands for quantum electrodynamics and TIR for total internal
reflection. The TIR confinement of QED photons is enhanced by the
fact the absorbedheat energy absorbed in the GST film is concentrated
in the TIR mode because of their high surface to volume ratio. The
QED photons having Planck energy beyond the ultraviolet produce
excitons by the photoelectric effect, the electrons and holes of which
reduce the GST film resistance.
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 waverider is proved to be a remarkably useful
configuration for hypersonic glide vehicle (HGV) in terms of the high
lift-to-drag ratio. Due to the severe aerodynamic heating and the
processing technical restriction, the sharp leading edge of waverider
should be blunted, and then the flow characteristics and the
aerodynamic performance along the trajectory will change. In this
paper, the flow characteristics of a HGV, including the rarefied gas
effect and transition phenomenon, were studied based on a reference
trajectory. A numerical simulation was carried out to study the
performance of the HGV under a typical condition.
Abstract: Column leach test has been performed to examine the
behavior of leaching of sodium, calcium and potassium in landfills.
In the column leach apparatus, two different layers of contaminated
and uncontaminated soils of different height ratios (ratio of depth of
contaminated soil to the depth of uncontaminated soil) are taken.
Water is poured from an overhead tank at a particular flowrate to the
inlet of the soil column for a certain ponding depth over the
contaminated soil. Subsequent infiltration causes leaching and the
leachates are collected from the bottom of the column. The
concentrations of Na, Ca and K in the leachate are measured using
flame photometry. The experiments are further extended by changing
the rates of flow from the overhead tank to the inlet of the column in
achieving the same ponding depth. The experiments are performed
for different scenarios in which the height ratios are altered and the
variations of concentrations of Na, Ca, and K are observed. The study
brings an estimation of leaching in landfill sites for different heights
and precipitation intensity where a ponding depth is maintained over
the landfill. It has been observed that the leaching behavior of Na,
Ca, and K are not similar. Calcium exhibits highest amount of
leaching compared to Sodium and Potassium under similar
experimental conditions.