Abstract: Vickers indentation is used to measure the hardness
of materials. In this study, numerical simulation of Vickers
indentation experiment was performed for Diamond like Carbon
(DLC) coated materials. DLC coatings were deposited on stainless
steel 304 substrates with Chromium buffer layer using RF Magnetron
and T-shape Filtered Cathodic Vacuum Arc Dual system The
objective of this research is to understand the elastic plastic
properties, stress strain distribution, ring and lateral crack growth and
propagation, penetration depth of indenter and delamination of
coating from substrate with effect of buffer layer thickness. The
effect of Poisson-s ratio of DLC coating was also analyzed. Indenter
penetration is more in coated materials with thin buffer layer as
compared to thicker one, under same conditions. Similarly, the
specimens with thinner buffer layer failed quickly due to high
residual stress as compared to the coated materials with reasonable
thickness of 200nm buffer layer. The simulation results suggested the
optimized thickness of 200 nm among the prepared specimens for
durable and long service.
Abstract: This article is focused on the calculation of heat
radiation intensity and its optimization on an aluminum mould
surface. The inside of the mould is sprinkled with a special powder
and its outside is heated by infra heaters located above the mould
surface, up to a temperature of 250°C. By this way artificial leathers
in the car industry are produced (e. g. the artificial leather on a car
dashboard). A mathematical model of heat radiation of infra heaters
on a mould surface is described in this paper. This model allows us to
calculate a heat-intensity radiation on the mould surface for the
concrete location of infra heaters above the mould surface. It is
necessary to ensure approximately the same heat intensity radiation
on the mould surface by finding a suitable location for the infra
heaters, and in this way the same material structure and color of
artificial leather. In the model we have used a genetic algorithm to
optimize the radiation intensity on the mould surface. Experimental
measured values for the heat radiation intensity by a sensor in the
surroundings of an infra heater are used for the calculation
procedures. A computational procedure was programmed in language
Matlab.
Abstract: Increase in using internet makes some problems that
one of them is "internet anxiety". Internet anxiety is a type of anxious
that people may feel during surfing internet or using internet for their
educational purpose, blogging or streaming to digital libraries. The
goal of this study is evaluating of internet anxiety among the
management students. In this research Ealy's internet anxiety
questionnaire, consists of positive and negative items, is completed
by 310 participants. According to the findings, about 64.7% of them
were equal or below to mean anxiety score (50). The distribution of
internet anxiety scores was normal and there was no meaningful
difference between men-s and women's anxiety level in this sample.
Results also showed that there is no meaningful difference of internet
anxiety level between different fields of study in Management. This
evaluation will help managers to perform gap analysis between the
existent level and the desired one. Future work would be providing
techniques for abating human anxiety while using internet via human
computer interaction techniques.
Abstract: The purpose of this paper is to provide an overview on methodological aspects of the information technology outsourcing (ITO) surveys, in an attempt to improve the data quality and reporting in survey research. It is based on a review of thirty articles on ITO surveys and focuses on two commonly explored dimensions of ITO, namely what are outsourced and why should there be ITO. This study highlights weaknesses in ITO surveys including lack of a clear definition of population, lack of information regarding the sampling method used, not citing the response rate, no information pertaining to pilot testing of survey instrument and absence of information on internal validity in the use or reporting of surveys. This study represents an attempt with a limited scope to point to shortfalls in the use survey methodology in ITO, and thus raise awareness among researchers in enhancing the reliability of survey findings.
Abstract: Electronic seal is an electronic device to check the
authenticity and integrity of freight containers at the point of arrival.
While RFID-based eSeals are gaining more acceptances and there are
also some standardization processes for these devices, a recent
research revealed that the current RFID-based eSeals are vulnerable to
various attacks. In this paper, we provide a feasible solution to
enhance the security of active RFID-based eSeals. Our approach is to
use an authentication and key agreement protocol between eSeal and
reader device, enabling data encryption and integrity check. Our
protocol is based on the use of block cipher AES, which is reasonable
since a block cipher can also be used for many other security purposes
including data encryption and pseudo-random number generation. Our
protocol is very simple, and it is applicable to low-end active RFID
eSeals.
Abstract: The present study has been taken to explore the
screening of in vitro antimicrobial activities of D-galactose-binding
sponge lectin (HOL-30). HOL-30 was purified from the marine
demosponge Halichondria okadai by affinity chromatography. The
molecular mass of the lectin was determined to be 30 kDa with a
single polypeptide by SDS-PAGE under non-reducing and reducing
conditions. HOL-30 agglutinated trypsinized and glutaraldehydefixed
rabbit and human erythrocytes with preference for type O
erythrocytes. The lectin was subjected to evaluation for inhibition of
microbial growth by the disc diffusion method against eleven human
pathogenic gram-positive and gram-negative bacteria. The lectin
exhibited strong antibacterial activity against gram-positive bacteria,
such as Bacillus megaterium and Bacillus subtilis. However, it did
not affect against gram-negative bacteria such as Salmonella typhi
and Escherichia coli. The largest zone of inhibition was recorded of
Bacillus megaterium (12 in diameter) and Bacillus subtilis (10 mm in
diameter) at a concentration of the lectin (250 μg/disc). On the other
hand, the antifungal activity of the lectin was investigated against six
phytopathogenic fungi based on food poisoning technique. The lectin
has shown maximum inhibition (22.83%) of mycelial growth of
Botrydiplodia theobromae at a concentration of 100 μg/mL media.
These findings indicate that the lectin may be of importance to
clinical microbiology and have therapeutic applications.
Abstract: Evaluation of contact pressure, surface and
subsurface contact stresses are essential to know the functional
response of surface coatings and the contact behavior mainly depends
on surface roughness, material property, thickness of layer and the
manner of loading. Contact parameter evaluation of real rough
surface contacts mostly relies on statistical single asperity contact
approaches. In this work, a three dimensional layered solid rough
surface in contact with a rigid flat is modeled and analyzed using
finite element method. The rough surface of layered solid is
generated by FFT approach. The generated rough surface is exported
to a finite element method based ANSYS package through which the
bottom up solid modeling is employed to create a deformable solid
model with a layered solid rough surface on top. The discretization
and contact analysis are carried by using the same ANSYS package.
The elastic, elastoplastic and plastic deformations are continuous in
the present finite element method unlike many other contact models.
The Young-s modulus to yield strength ratio of layer is varied in the
present work to observe the contact parameters effect while keeping
the surface roughness and substrate material properties as constant.
The contacting asperities attain elastic, elastoplastic and plastic states
with their continuity and asperity interaction phenomena is inherently
included. The resultant contact parameters show that neighboring
asperity interaction and the Young-s modulus to yield strength ratio
of layer influence the bulk deformation consequently affect the
interface strength.
Abstract: A two-dimensional numerical simulation of the contribution
of both inertial and aerodynamic forces on the blade loads of
a Vertical-Axis Wind Turbine (VAWT) is presented. After describing
the computational model and the relative validation procedure, a
complete campaign of simulations - based on full RANS unsteady
calculations - is proposed for a three-bladed rotor architecture characterized
by a NACA 0021 airfoil. For each analyzed angular velocity,
the combined effect of pressure and viscous forces acting on every
rotor blade are compared to the corresponding centrifugal forces,
due to the revolution of the turbine, thus achieving a preliminary
estimation of the correlation between overall rotor efficiency and
structural blade loads.
Abstract: This paper describes a prototype aircraft that can fly
slowly, safely and transmit wireless video for tasks like reconnaissance,
surveillance and target acquisition. The aircraft is designed to
fly in closed quarters like forests, buildings, caves and tunnels which
are often spacious but GPS reception is poor. Envisioned is that a
small, safe and slow flying vehicle can assist in performing dull,
dangerous and dirty tasks like disaster mitigation, search-and-rescue
and structural damage assessment.
Abstract: The purpose of this study was to investigate effects of
modality and redundancy principles on music theory learning among
pupils of different anxiety levels. The lesson of music theory was
developed in three different modes, audio and image (AI), text with
image (TI) and audio with image and text (AIT). The independent
variables were the three modes of courseware. The moderator
variable was the anxiety level, while the dependent variable was the
post test score. The study sample consisted of 405 third-grade pupils.
Descriptive and inferential statistics were conducted to analyze the
collected data. Analyses of covariance (ANCOVA) and Post hoc
were carried out to examine the main effects as well as the
interaction effects of the independent variables on the dependent
variable. The findings of this study showed that medium anxiety
pupils performed significantly better than low and high anxiety
pupils in all the three treatment modes. The AI mode was found to
help pupils with high anxiety significantly more than the TI and AIT
modes.
Abstract: Bioinformatics and computational biology involve
the use of techniques including applied mathematics,
informatics, statistics, computer science, artificial intelligence,
chemistry, and biochemistry to solve biological problems
usually on the molecular level. Research in computational
biology often overlaps with systems biology. Major research
efforts in the field include sequence alignment, gene finding,
genome assembly, protein structure alignment, protein structure
prediction, prediction of gene expression and proteinprotein
interactions, and the modeling of evolution. Various
global rearrangements of permutations, such as reversals and
transpositions,have recently become of interest because of their
applications in computational molecular biology. A reversal is
an operation that reverses the order of a substring of a permutation.
A transposition is an operation that swaps two adjacent
substrings of a permutation. The problem of determining the
smallest number of reversals required to transform a given
permutation into the identity permutation is called sorting by
reversals. Similar problems can be defined for transpositions
and other global rearrangements. In this work we perform a
study about some genome rearrangement primitives. We show
how a genome is modelled by a permutation, introduce some
of the existing primitives and the lower and upper bounds
on them. We then provide a comparison of the introduced
primitives.
Abstract: This paper explores the knowledge and attitude of
women and men in decision making on pap smear screening. This
qualitative study recruited 52 respondents with 44 women and 8 men,
using the purposive sampling with snowballing technique through indepth
interviews. This study demonstrates several key findings:
Female respondents have better knowledge compared to male. Most
of the women perceived that pap smear screening is beneficial and
important, but to proceed with the test is still doubtful. Male
respondents were supportive in terms of sending their spouses to the
health facilities or give more freedom to their wives to choose and
making decision on their own health due to prominent reason that
women know best on their own health. It is expected that the results
from this study will provide useful guideline for healthcare providers
to prepare any action/intervention to provide an extensive education
to improve people-s knowledge and attitude towards pap smear.
Abstract: The article investigates how 14- to 15- year-olds build informal conceptions of inferential statistics as they engage in a modelling process and build their own computer simulations with dynamic statistical software. This study proposes four primary phases of informal inferential reasoning for the students in the statistical modeling and simulation process. Findings show shifts in the conceptual structures across the four phases and point to the potential of all of these phases for fostering the development of students- robust knowledge of the logic of inference when using computer based simulations to model and investigate statistical questions.
Abstract: In a bi-fuel diesel engine, the carburetor plays a vital
role in switching from fuel gas to petrol mode operation and viceversa.
The carburetor is the most important part of the fuel system of
a diesel engine. All diesel engines carry variable venturi mixer
carburetors. The basic operation of the carburetor mainly depends on
the restriction barrel called the venturi. When air flows through the
venturi, its speed increases and its pressure decreases. The main
challenge focuses on designing a mixing device which mixes the
supplied gas is the incoming air at an optimum ratio. In order to
surmount the identified problems, the way fuel gas and air flow in
the mixer have to be analyzed. In this case, the Computational Fluid
Dynamics or CFD approach is applied in design of the prototype
mixer. The present work is aimed at further understanding of the air
and fuel flow structure by performing CFD studies using a software
code. In this study for mixing air and gas in the condition that has
been mentioned in continuance, some mixers have been designed.
Then using of computational fluid dynamics, the optimum mixer has
been selected. The results indicated that mixer with 12 holes can
produce a homogenous mixture than those of 8-holes and 6-holes
mixer. Also the result showed that if inlet convergency was smoother
than outlet divergency, the mixture get more homogenous, the reason
of that is in increasing turbulence in outlet divergency.
Abstract: This paper describes vibration analysis using the finite
element method for a small earphone, especially for the diaphragm
shape with a low-rigidity. The viscoelastic diaphragm is supported by
multiple nonlinear concentrated springs with linear hysteresis
damping. The restoring forces of the nonlinear springs have cubic
nonlinearity. The finite elements for the nonlinear springs with
hysteresis are expressed and are connected to the diaphragm that is
modeled by linear solid finite elements in consideration of a complex
modulus of elasticity. Further, the discretized equations in physical
coordinates are transformed into the nonlinear ordinary coupled
equations using normal coordinates corresponding to the linear natural
modes. We computed the nonlinear stationary and non-stationary
responses due to the internal resonance between modes with large
amplitude in the nonlinear springs and elastic modes in the diaphragm.
The non-stationary motions are confirmed as the chaos due to the
maximum Lyapunov exponents with a positive number. From the time
histories of the deformation distribution in the chaotic vibration, we
identified nonlinear modal couplings.
Abstract: Health problems linked to urban growth are current
major concerns of developing countries. In 2002 and 2005, an
interdisciplinary program “Populations et Espaces ├á Risques
SANitaires" (PERSAN) was set up under the patronage of the
Development and Research Institute. Centered on health in
Cameroon-s urban environment, the program mainly sought to (i)
identify diarrhoea risk factors in Yaoundé, (ii) to measure their
prevalence and apprehend their spatial distribution. The crosssectional
epidemiological study that was carried out revealed a
diarrheic prevalence of 14.4% (437 cases of diarrhoea on the 3,034
children examined). Also, among risk factors studied, household
refuse management methods used by city dwellers were statistically
associated to these diarrhoeas. Moreover, it happened that levels of
diarrhoeal attacks varied consistently from one neighbourhood to
another because of the discrepancy urbanization process of the
Yaoundé metropolis.
Abstract: This article presents the results using a parametric approach and a Wavelet Transform in analysing signals emitting from the sperm whale. The extraction of intrinsic characteristics of these unique signals emitted by marine mammals is still at present a difficult exercise for various reasons: firstly, it concerns non-stationary signals, and secondly, these signals are obstructed by interfering background noise. In this article, we compare the advantages and disadvantages of both methods: Auto Regressive models and Wavelet Transform. These approaches serve as an alternative to the commonly used estimators which are based on the Fourier Transform for which the hypotheses necessary for its application are in certain cases, not sufficiently proven. These modern approaches provide effective results particularly for the periodic tracking of the signal's characteristics and notably when the signal-to-noise ratio negatively effects signal tracking. Our objectives are twofold. Our first goal is to identify the animal through its acoustic signature. This includes recognition of the marine mammal species and ultimately of the individual animal (within the species). The second is much more ambitious and directly involves the intervention of cetologists to study the sounds emitted by marine mammals in an effort to characterize their behaviour. We are working on an approach based on the recordings of marine mammal signals and the findings from this data result from the Wavelet Transform. This article will explore the reasons for using this approach. In addition, thanks to the use of new processors, these algorithms once heavy in calculation time can be integrated in a real-time system.
Abstract: One of the most important causes of accidents is
driver fatigue. To reduce the accidental rate, the driver needs a
quick nap when feeling sleepy. Hence, searching for the minimum
time period of nap is a very challenging problem. The purpose of
this paper is twofold, i.e. to investigate the possible fastest time
period for nap and its relationship with stage 2 sleep, and to
develop an automatic stage 2 sleep detection and alarm device. The
experiment for this investigation is designed with 21 subjects. It
yields the result that waking up the subjects after getting into stage
2 sleep for 3-5 minutes can efficiently reduce the sleepiness.
Furthermore, the automatic stage 2 sleep detection and alarm
device yields the real-time detection accuracy of approximately
85% which is comparable with the commercial sleep lab system.
Abstract: This paper presents the findings of two experiments that were performed on the Redundancy in Wireless Connection Model (RiWC) using the 802.11b standard. The experiments were simulated using OPNET 11.5 Modeler software. The first was aimed at finding the maximum number of simultaneous Voice over Internet Protocol (VoIP) users the model would support under the G.711 and G.729 codec standards when the packetization interval was 10 milliseconds (ms). The second experiment examined the model?s VoIP user capacity using the G.729 codec standard along with background traffic using the same packetization interval as in the first experiment. To determine the capacity of the model under various experiments, we checked three metrics: jitter, delay and data loss. When background traffic was added, we checked the response time in addition to the previous three metrics. The findings of the first experiment indicated that the maximum number of simultaneous VoIP users the model was able to support was 5, which is consistent with recent research findings. When using the G.729 codec, the model was able to support up to 16 VoIP users; similar experiments in current literature have indicated a maximum of 7 users. The finding of the second experiment demonstrated that the maximum number of VoIP users the model was able to support was 12, with the existence of background traffic.
Abstract: The result of process of territory-s development is the territory-s state of development (TSoD), which is pointed towards the provision and improvement of people-s life conditions. The authors offer to measure the TSoD according to their own developed model. Using the available statistical data regarding the values of model-s elements, the authors empirically show which element mainly determines the TSoD. The findings of the research showed that the key elements of the TSoD are the “Material welfare of people" and “People-s health". Performing a deeper statistical analysis of correlation between these elements, it turned out that it is not so necessary for a country to be bent on trying to increase the material growth of a territory, because a relatively high index of life expectancy at birth could be ensured also by much more modest material resources. On the other hand, the economical feedback of longer lifespan within countries with lower material performance is also relatively low.