Abstract: The storage of thermal energy as a latent heat of phase
change material (PCM) has created considerable interest among
researchers in recent times. Here, an attempt is made to carry out
numerical investigations to analyze the performance of latent heat
storage units (LHSU) employing phase change material. The
mathematical model developed is based on an enthalpy formulation.
Freezing time of PCM packed in three different shaped containers
viz. rectangular, cylindrical and cylindrical shell is compared. The
model is validated with the results available in the literature. Results
show that for the same mass of PCM and surface area of heat
transfer, cylindrical shell container takes the least time for freezing
the PCM and this geometric effect is more pronounced with an
increase in the thickness of the shell than that of length of the shell.
Abstract: Studies revealing the positive relationship between
trade and income are often criticized with the argument that
“development should mean more than rising incomes". Taking this
argument as a base and utilizing panel data, Davies and Quinlivan [1]
have demonstrated that increases in trade are positively associated
with future increases in social welfare as measured by the Human
Development Index (HDI). The purpose of this study is twofold:
Firstly, utilizing an income based country classification; it is aimed
to investigate whether the positive association between foreign trade
and HDI is valid within all country groups. Secondly, keeping the
same categorization as a base; it is aimed to reveal whether the
positive link between trade and HDI still exists when the income
components of the index are excluded. Employing a panel data
framework of 106 countries, this study reveals that the positive link
between trade and human development is valid only for high and
medium income countries. Moreover, the positive link between trade
and human development diminishes in lower-medium income
countries when only non-income components of the index are taken
into consideration.
Abstract: High voltage generators are being subject to higher
voltage rating and are being designed to operate in harsh conditions.
Stator windings are the main component of generators in which
Electrical, magnetical and thermal stresses remain major failures for
insulation degradation accelerated aging. A large number of
generators failed due to stator winding problems, mainly insulation
deterioration. Insulation degradation assessment plays vital role in the
asset life management. Mostly the stator failure is catastrophic
causing significant damage to the plant. Other than generation loss,
stator failure involves heavy repair or replacement cost. Electro
thermal analysis is the main characteristic for improvement design of
stator slot-s insulation. Dielectric parameters such as insulation
thickness, spacing, material types, geometry of winding and slot are
major design consideration. A very powerful method available to
analyze electro thermal performance is Finite Element Method
(FEM) which is used in this paper. The analysis of various stator coil
and slot configurations are used to design the better dielectric system
to reduce electrical and thermal stresses in order to increase the
power of generator in the same volume of core. This paper describes
the process used to perform classical design and improvement
analysis of stator slot-s insulation.
Abstract: In this era of technology, fueled by the pervasive usage of the internet, security is a prime concern. The number of new attacks by the so-called “bots", which are automated programs, is increasing at an alarming rate. They are most likely to attack online registration systems. Technology, called “CAPTCHA" (Completely Automated Public Turing test to tell Computers and Humans Apart) do exist, which can differentiate between automated programs and humans and prevent replay attacks. Traditionally CAPTCHA-s have been implemented with the challenge involved in recognizing textual images and reproducing the same. We propose an approach where the visual challenge has to be read out from which randomly selected keywords are used to verify the correctness of spoken text and in turn detect the presence of human. This is supplemented with a speaker recognition system which can identify the speaker also. Thus, this framework fulfills both the objectives – it can determine whether the user is a human or not and if it is a human, it can verify its identity.
Abstract: Numerical studies have been carried out using a two
dimensional code to examine the influence of pressure / thrust
transient of solid propellant rockets at liftoff. This code solves
unsteady Reynolds-averaged thin-layer Navier–Stokes equations by
an implicit LU-factorization time-integration method. The results
from the parametric study indicate that when the port is narrow there
is a possibility of increase in pressure / thrust-rise rate due to
relatively high flame spread rate. Parametric studies further reveal
that flame spread rate can be altered by altering the propellant
properties, igniter jet characteristics and nozzle closure burst pressure
without altering the grain configuration and/or the mission
demanding thrust transient. We observed that when the igniter
turbulent intensity is relatively low the vehicle could liftoff early due
to the early flow choking of the rocket nozzle. We concluded that the
high pressurization-rate has structural implications at liftoff in
addition to transient burning effect. Therefore prudent selection of the
port geometry and the igniter, for meeting the mission requirements,
within the given envelop are meaningful objectives for any designer
for the smooth liftoff of solid propellant rockets.
Abstract: Several methods are available for weight and shape
optimization of structures, among which Evolutionary Structural
Optimization (ESO) is one of the most widely used methods. In ESO,
however, the optimization criterion is completely case-dependent.
Moreover, only the improving solutions are accepted during the
search. In this paper a Simulated Annealing (SA) algorithm is used
for structural optimization problem. This algorithm differs from other
random search methods by accepting non-improving solutions. The
implementation of SA algorithm is done through reducing the
number of finite element analyses (function evaluations).
Computational results show that SA can efficiently and effectively
solve such optimization problems within short search time.
Abstract: This paper presents an exact pruning algorithm with
adaptive pruning interval for general dynamic neural networks
(GDNN). GDNNs are artificial neural networks with internal dynamics.
All layers have feedback connections with time delays to the
same and to all other layers. The structure of the plant is unknown, so
the identification process is started with a larger network architecture
than necessary. During parameter optimization with the Levenberg-
Marquardt (LM) algorithm irrelevant weights of the dynamic neural
network are deleted in order to find a model for the plant as
simple as possible. The weights to be pruned are found by direct
evaluation of the training data within a sliding time window. The
influence of pruning on the identification system depends on the
network architecture at pruning time and the selected weight to be
deleted. As the architecture of the model is changed drastically during
the identification and pruning process, it is suggested to adapt the
pruning interval online. Two system identification examples show
the architecture selection ability of the proposed pruning approach.
Abstract: The cumulative conformance count (CCC) charts are
widespread in process monitoring of high-yield manufacturing.
Recently, it is found the use of variable sampling interval (VSI)
scheme could further enhance the efficiency of the standard CCC
charts. The average time to signal (ATS) a shift in defect rate has
become traditional measure of efficiency of a chart with the VSI
scheme. Determining the ATS is frequently a difficult and tedious
task. A simple method based on a finite Markov Chain approach for
modeling the ATS is developed. In addition, numerical results are
given.
Abstract: The purpose of this research was to study the factors
that influenced the success of mobile phone entrepreneurs at Central
Plaza. The sample group included 187 entrepreneurs at Central Plaza.
A questionnaire was utilized as a tool to collect data. Statistics used
in this research included frequency, percentage, mean, and standard
deviation. Independent- sample t- test, one way ANOVA, and
multiple regression analysis. Data were analyzed by using Statistical
Package for the Social Sciences.The findings disclosed that the
majority of respondents were male between 25-40 years old, and held
an undergraduate degree. The average income of respondents was
between 15,001-25,000 baht. The majority of respondents had less
than 5 years of working experience.
In terms of personality, the findings revealed that expression and
agreement were ranked at the highest level. Whereas, emotion
stability, consciousness, open to new experience were ranked at high.
From the hypotheses testing, the findings revealed that different
genders had different success in their mobile phone business with
different income from the last 6 months. However, difference in age,
income, level of education, and experience affected the success in
terms of income, number of customers, and overall success of
business. Moreover, the factors of personalities included expression,
agreement, emotion stability, consciousness, open to new experience,
and competitive strategy. From the findings, these factors were able
to predict mobile phone business success at 66.9 percent.
Abstract: This study investigated the effect of germination on chemical compositions, physio-chemical properties of malted (germinated) red sorghum flours and evaluated characteristics of gluten free breads from sorghum flour. Results showed that germinated sorghum flour had higher amylase activity, swelling power and solubility at 95°C, but lower in the peak, break down, final and set back viscosities than ungerminated sample (p≤0.05). Five gluten free breads made from sorghum flour blends, with different ratios of ungerminated and germinated sorghum flour, were compared for the physical properties with those made from wheat flour. Crumb hardness, cohesiveness, gumminess and chewiness of sorghum breads were found significantly higher than those of wheat bread. With increasing of ungerminated flour proportion, the bread hardness increased while the cohesiveness declined. Sorghum breads appeared red to human eyes with a*values of 10.41-15.77.Their crust and crumb colors differed significantly from those of wheat bread.
Abstract: The gustatory system allows animals to distinguish
varieties of food and affects greatly the consumption of food, hence
the health and growth of animals. In the current study, we
investigated the histogenesis of vallate papillae (VLP) in the rabbit
tongue using light and scanning electron microscopy. Samples were
obtained from rabbit embryos at the embryonic days 16-30 (E16-30),
and from newborns until maturity; 6 months. At E16, the first
primordia of vallate papillae were observed as small pits on the
surface epithelium of the tongue-s root. At E18, the caudal part was
prominent with loose mesenchymal tissue core; meanwhile the rostral
part of the papilla was remained as a thick mass of epithelial cells. At
E20-24, the side epithelium formed the primitive annular groove. At
E26, the primitive taste buds appeared only at the papillary surface
and reached their maturity by E28. The annular groove started to
appear at E26 became more defined at E28. The definitive vallate
papillae with substantial number of apparently mature taste buds
were observed by the end of the second week. We conclude that the
vallate papillae develop early and mature during the early postnatal
life.
Abstract: This paper presents the experimental results of the
investigation of various properties related to the durability and longterm
performance of mortars made of Fly Ash blended cement, FA
and Ordinary Portland cement, OPC. The properties that were
investigated in an experimental program include; equilibration of
specimen in different relative humidity, determination of total
porosity, compressive strength, chloride permeability index, and
electrical resistivity. Fly Ash blended cement mortar specimens
exhibited 10% to 15% lower porosity when measured at equilibrium
conditions in different relative humidities as compared to the
specimens made of OPC mortar, which resulted in 6% to 8% higher
compressive strength of FA blended cement mortar specimens. The
effects of ambient relative humidity during sample equilibration on
porosity and strength development were also studied. For specimens
equilibrated in higher relative humidity conditions, such as 75%, the
total porosity of different mortar specimens was between 35% to 50%
less than the porosity of samples equilibrated in 12% relative
humidity, consequently leading to higher compressive strengths of
these specimens.A valid statistical correlation between values of
compressive strength, porosity and the degree of saturation was
obtained. Measured values of chloride permeability index of fly ash
blended cement mortar were obtained as one fourth to one sixth of
those measured for OPC mortar specimens, which indicates high
resistance against chloride ion penetration in FA blended cement
specimens, hence resulting in a highly durable mortar.
Abstract: Bacterial molecular chaperone DnaK plays an essential role in protein folding, stress response and transmembrane targeting of proteins. DnaKs from many bacterial species, including Escherichia coli, Salmonella typhimurium and Haemophilus infleunzae are the molecular targets for the insect-derived antimicrobial peptide pyrrhocoricin. Pyrrhocoricin-like peptides bind in the substrate recognition tunnel. Despite the high degree of crossspecies sequence conservation in the substrate-binding tunnel, some bacteria are not sensitive to pyrrhocoricin. This work addresses the molecular mechanism of resistance of Helicobacter pylori DnaK to pyrrhocoricin. Homology modelling, structural and sequence analysis identify a single aminoacid substitution at the interface between the lid and the β-sandwich subdomains of the DnaK substrate-binding domain as the major determinant for its resistance.
Abstract: In this paper we use the property of co-occurrence
matrix in finding parallel lines in binary pictures for fingerprint
identification. In our proposed algorithm, we reduce the noise by
filtering the fingerprint images and then transfer the fingerprint
images to binary images using a proper threshold. Next, we divide
the binary images into some regions having parallel lines in the same
direction. The lines in each region have a specific angle that can be
used for comparison. This method is simple, performs the
comparison step quickly and has a good resistance in the presence of
the noise.
Abstract: Intrusion detection is a mechanism used to protect a
system and analyse and predict the behaviours of system users. An
ideal intrusion detection system is hard to achieve due to
nonlinearity, and irrelevant or redundant features. This study
introduces a new anomaly-based intrusion detection model. The
suggested model is based on particle swarm optimisation and
nonlinear, multi-class and multi-kernel support vector machines.
Particle swarm optimisation is used for feature selection by applying
a new formula to update the position and the velocity of a particle;
the support vector machine is used as a classifier. The proposed
model is tested and compared with the other methods using the KDD
CUP 1999 dataset. The results indicate that this new method achieves
better accuracy rates than previous methods.
Abstract: Saturated hydraulic conductivity is one of the soil
hydraulic properties which is widely used in environmental studies
especially subsurface ground water. Since, its direct measurement is
time consuming and therefore costly, indirect methods such as
pedotransfer functions have been developed based on multiple linear
regression equations and neural networks model in order to estimate
saturated hydraulic conductivity from readily available soil
properties e.g. sand, silt, and clay contents, bulk density, and organic
matter. The objective of this study was to develop neural networks
(NNs) model to estimate saturated hydraulic conductivity from
available parameters such as sand and clay contents, bulk density,
van Genuchten retention model parameters (i.e. r
θ , α , and n) as well
as effective porosity. We used two methods to calculate effective
porosity: : (1) eff s FC φ =θ -θ , and (2) inf φ =θ -θ eff s , in which s
θ is
saturated water content, FC θ is water content retained at -33 kPa
matric potential, and inf θ is water content at the inflection point.
Total of 311 soil samples from the UNSODA database was divided
into three groups as 187 for the training, 62 for the validation (to
avoid over training), and 62 for the test of NNs model. A commercial
neural network toolbox of MATLAB software with a multi-layer
perceptron model and back propagation algorithm were used for the
training procedure. The statistical parameters such as correlation
coefficient (R2), and mean square error (MSE) were also used to
evaluate the developed NNs model. The best number of neurons in
the middle layer of NNs model for methods (1) and (2) were
calculated 44 and 6, respectively. The R2 and MSE values of the test
phase were determined for method (1), 0.94 and 0.0016, and for
method (2), 0.98 and 0.00065, respectively, which shows that method
(2) estimates saturated hydraulic conductivity better than method (1).
Abstract: In this study, we sought to investigate the mercury
removal efficiency of manganese oxides from natural gas. The
fundamental studies on mercury removal with manganese oxides
sorbents were carried out in a laboratory scale fixed bed reactor at 30
°C with a mixture of methane (20%) and nitrogen gas laden with 4.8
ppb of elemental mercury. Manganese oxides with varying surface
area and crystalline phase were prepared by conventional precipitation
method in this study. The effects of surface area, crystallinity and
other metal oxides on mercury removal efficiency were investigated.
Effect of Ag impregnation on mercury removal efficiency was also
investigated. Ag supported on metal oxide such titania and zirconia as
reference materials were also used in this study for comparison. The
characteristics of mercury removal reaction with manganese oxide
was investigated using a temperature programmed desorption (TPD)
technique.
Manganese oxides showed very high Hg removal activity (about
73-93% Hg removal) for first time use. Surface area of the manganese
oxide samples decreased after heat-treatment and resulted in complete
loss of Hg removal ability for repeated use after Hg desorption in the
case of amorphous MnO2, and 75% loss of the initial Hg removal
activity for the crystalline MnO2. Mercury desorption efficiency of
crystalline MnO2 was very low (37%) for first time use and high (98%)
after second time use. Residual potassium content in MnO2 may have
some effect on the thermal stability of the adsorbed Hg species.
Desorption of Hg from manganese oxides occurs at much higher
temperatures (with a peak at 400 °C) than Ag/TiO2 or Ag/ZrO2.
Mercury may be captured on manganese oxides in the form of mercury
manganese oxide.
Abstract: Many multimedia communication applications require a
source to transmit messages to multiple destinations subject to quality
of service (QoS) delay constraint. To support delay constrained
multicast communications, computer networks need to guarantee an
upper bound end-to-end delay from the source node to each of
the destination nodes. This is known as multicast delay problem.
On the other hand, if the same message fails to arrive at each
destination node at the same time, there may arise inconsistency and
unfairness problem among users. This is related to multicast delayvariation
problem. The problem to find a minimum cost multicast
tree with delay and delay-variation constraints has been proven to
be NP-Complete. In this paper, we propose an efficient heuristic
algorithm, namely, Economic Delay and Delay-Variation Bounded
Multicast (EDVBM) algorithm, based on a novel heuristic function,
to construct an economic delay and delay-variation bounded multicast
tree. A noteworthy feature of this algorithm is that it has very high
probability of finding the optimal solution in polynomial time with
low computational complexity.
Abstract: A strategy is implemented to find the improved configuration design of an existing aircraft structure by executing topology and shape optimizations. Structural analysis of the Initial Design Space is performed in ANSYS under the loads pertinent to operating and ground conditions. By using the FEA results and data, an initial optimized layout configuration is attained by exploiting nonparametric topology optimization in TOSCA software. Topological optimized surfaces are then smoothened and imported in ANSYS to develop the geometrical features. Nodes at the critical locations of resulting voids are selected for sketching rough profiles. Rough profiles are further refined and CAD feasible geometric features are generated. The modified model is then analyzed under the same loadings and constraints as defined for topology optimization. Shape at the peak stress concentration areas are further optimized by exploiting the shape optimization in TOSCA.shape module. The harmonized stressed model with the modified surfaces is then imported in CATIA to develop the final design.
Abstract: In this paper we investigate the watermarking authentication when applied to medical imagery field. We first give an overview of watermarking technology by paying attention to fragile watermarking since it is the usual scheme for authentication.We then analyze the requirements for image authentication and integrity in medical imagery, and we show finally that invertible schemes are the best suited for this particular field. A well known authentication method is studied. This technique is then adapted here for interleaving patient information and message authentication code with medical images in a reversible manner, that is using lossless compression. The resulting scheme enables on a side the exact recovery of the original image that can be unambiguously authenticated, and on the other side, the patient information to be saved or transmitted in a confidential way. To ensure greater security the patient information is encrypted before being embedded into images.