Abstract: The main purpose of this work was verify the
influence of the accelerated carbonation in the physical and
mechanical properties of the hybrid composites, reinforced with
micro and nanofibers and composites with microfibers. The
composites were produced by the slurry vacuum dewatering method,
followed by pressing. It was produced using two formulations: 8% of
eucalyptus pulp + 1% of the nanofibrillated cellulose and 9% of
eucalyptus pulp, both were subjected to accelerated carbonation. The
results showed that the accelerated carbonation contributed to
improve the physical and mechanical properties of the hybrid
composites and of the composites reinforced with microfibers
(eucalyptus pulp).
Abstract: The in-cylinder flow and mixture formations are
significant in view of today’s increasing concern on environmental
issues and stringent emission regulations. In this paper, the numerical
simulations of a SI engine at different engine speeds (2000-5000
rpm) at fixed intake flow pressure of 1 bar are studied using the AVL
FIRE software. The simulation results show that when the engine
speed at fixed intake flow pressure is increased, the volumetric
efficiency of the engine decreases. This is due to a richer fuel
conditions near the engine cylinder wall when engine speed is
increased. Significant effects of impingement are also noted on the
upper and side walls of the engine cylinder. These variations in
mixture formation before ignition could affect the thermodynamics
efficiency and specific fuel consumption that would lead to a reduced
engine performance.
Abstract: In this paper an isolated wind-diesel hybrid power
system has been considered for reactive power control study having
an induction generator for wind power conversion and synchronous
alternator with automatic voltage regulator (AVR) for diesel unit is
presented. The dynamic voltage stability evaluation is dependent on
small signal analysis considering a Static VAR Compensator (SVC)
and IEEE type -I excitation system. It's shown that the variable
reactive power source like SVC is crucial to meet the varying
demand of reactive power by induction generator and load and to
acquire an excellent voltage regulation of the system with minimum
fluctuations. Integral square error (ISE) criterion can be used to
evaluate the optimum setting of gain parameters. Finally the dynamic
responses of the power systems considered with optimum gain setting
will also be presented.
Abstract: Mammography has been one of the most reliable
methods for early detection of breast cancer. There are different
lesions which are breast cancer characteristic such as
microcalcifications, masses, architectural distortions and bilateral
asymmetry. One of the major challenges of analysing digital
mammogram is how to extract efficient features from it for accurate
cancer classification. In this paper we proposed a hybrid feature
extraction method to detect and classify all four signs of breast
cancer. The proposed method is based on multiscale surrounding
region dependence method, Gabor filters, multi fractal analysis,
directional and morphological analysis. The extracted features are
input to self adaptive resource allocation network (SRAN) classifier
for classification. The validity of our approach is extensively
demonstrated using the two benchmark data sets Mammographic
Image Analysis Society (MIAS) and Digital Database for Screening
Mammograph (DDSM) and the results have been proved to be
progressive.
Abstract: Aluminum hybrid reinforcement technology is a
response to the dynamic ever increasing service requirements of such
industries as transportation, aerospace, automobile, marine, etc. It is
unique in that it offers a platform of almost unending combinations of
materials to produce various hybrid composites. This article reviews
the studies carried out on various combinations of aluminum hybrid
composite and the effects on mechanical, physical and chemical
properties. It is observed that the extent of enhancement of these
properties of hybrid composites is strongly dependent on the nature
of the reinforcement, its hardness, particle size, volume fraction,
uniformity of dispersion within the matrix and the method of hybrid
production.
Abstract: This paper presents a hybrid fuzzy logic control
strategy for a unicycle trajectory following robot on irregular terrains.
In literature, researchers have presented the design of path tracking
controllers of mobile robots on non-frictional surface. In this work,
the robot is simulated to drive on irregular terrains with contrasting
frictional profiles of peat and rough gravel. A hybrid fuzzy logic
controller is utilised to stabilise and drive the robot precisely with the
predefined trajectory and overcome the frictional impact. The
controller gains and scaling factors were optimised using spiral
dynamics optimisation algorithm to minimise the mean square error
of the linear and angular velocities of the unicycle robot. The robot
was simulated on various frictional surfaces and terrains and the
controller was able to stabilise the robot with a superior performance
that is shown via simulation results.
Abstract: This paper deals with the problem of automatic rule
generation for fuzzy systems design. The proposed approach is based
on hybrid artificial bee colony (ABC) optimization and weighted least
squares (LS) method and aims to find the structure and parameters of
fuzzy systems simultaneously. More precisely, two ABC based fuzzy
modeling strategies are presented and compared. The first strategy
uses global optimization to learn fuzzy models, the second one
hybridizes ABC and weighted least squares estimate method. The
performances of the proposed ABC and ABC-LS fuzzy modeling
strategies are evaluated on complex modeling problems and compared
to other advanced modeling methods.
Abstract: In this paper, we have proposed a parallel IDS and
honeypot based approach to detect and analyze the unknown and
known attack taxonomy for improving the IDS performance and
protecting the network from intruders. The main theme of our
approach is to record and analyze the intruder activities by using both
the low and high interaction honeypots. Our architecture aims to
achieve the required goals by combing signature based IDS,
honeypots and generate the new signatures. The paper describes the
basic component, design and implementation of this approach and
also demonstrates the effectiveness of this approach to reduce the
probability of network attacks.
Abstract: Renewable energy is derived from natural processes
that are replenished constantly. Included in the definition is
electricity and heat generated from solar, wind, ocean, hydropower,
biomass, geothermal resources, and bio-fuels and hydrogen derived
from renewable resources. Each of these sources has unique
characteristics which influence how and where they are used. This
paper presents the modeling the simulation of solar and hydro hybrid
energy sources in MATLAB/SIMULINK environment. It simulates
all quantities of Hybrid Electrical Power system (HEPS) such as AC
output current of the inverter that injected to the load/grid, load
current, grid current. It also simulates power output from PV and
Hydraulic Turbine Generator (HTG), power delivered to or from grid
and finally power factor of the inverter for PV, HTG and grid. The
proposed circuit uses instantaneous p-q (real-imaginary) power
theory.
Abstract: Lately, asynchronous discussion forum is integrated in
higher educational institutions as it may increase learning process,
learners’ understanding, achievement and knowledge construction.
The asynchronous discussion forum is used to complement the
traditional, face-to-face learning session in hybrid learning courses.
However, studies have proven that students’ engagement in online
forums is still unconvincing. Thus, the aim of this study is to
investigate the motivating factors and obstacles that affect the
learners’ engagement in asynchronous discussion forum. This study
is carried out in one of the public higher educational institutions in
Malaysia with 18 postgraduate students as samples. The authors have
developed a 40-items questionnaire based on literature review. The
results indicate several factors that have encouraged or limited
students’ engagement in asynchronous discussion forum: (a) the
practices or behaviors of peers, or instructors, (b) the needs for the
discussions, (c) the learners’ personalities, (d) constraints in
continuing the discussion forum, (e) lack of ideas, (f) the level of
thoughts, (g) the level of knowledge construction, (h) technical
problems, (i) time constraints and (j) misunderstanding. This study
suggests some recommendations to increase the students’
engagement in online forums. Finally, based upon the findings, some
implications are proposed for further research.
Abstract: This paper presents a method for the efficient
implementation of a unidirectional or bidirectional DC/DC converter.
The DC/DC converter is used essentially for energy exchange
between the low voltage service battery and a high voltage battery
commonly found in Electric Vehicle applications. In these
applications, apart from cost, efficiency of design is an important
characteristic. A useful way to reduce the size of electronic
equipment in the electric vehicles is proposed in this paper. The
technique simplifies the mechanical complexity and maximizes the
energy usage using the latest converter control techniques. Moreover
a bidirectional battery charger for hybrid electric vehicles is also
implemented in this paper. Several simulations on the test system
have been carried out in Matlab/Simulink environment. The results
exemplify the robustness of the proposed design methodology in case
of a 1.5 KW DC-DC converter.
Abstract: Web-based Cognitive Writing Instruction (WeCWI) is
a hybrid e-framework for the development of a web-based instruction
(WBI), which contributes towards instructional design and language
development. WeCWI divides its contribution in instructional design
into macro and micro perspectives. In macro perspective, being a 21st
century educator by disseminating knowledge and sharing ideas with
the in-class and global learners is initiated. By leveraging the virtue
of technology, WeCWI aims to transform an educator into an
aggregator, curator, publisher, social networker and ultimately, a
web-based instructor. Since the most notable contribution of
integrating technology is being a tool of teaching as well as a
stimulus for learning, WeCWI focuses on the use of contemporary
web tools based on the multiple roles played by the 21st century
educator. The micro perspective in instructional design draws
attention to the pedagogical approaches focusing on three main
aspects: reading, discussion, and writing. With the effective use of
pedagogical approaches through free reading and enterprises,
technology adds new dimensions and expands the boundaries of
learning capacity. Lastly, WeCWI also imparts the fundamental
theories and models for web-based instructors’ awareness such as
interactionist theory, cognitive information processing (CIP) theory,
computer-mediated communication (CMC), e-learning interactionalbased
model, inquiry models, sensory mind model, and leaning styles
model.
Abstract: One- and two-dimensional carbon nanostructures with
sp2 hybridization of carbon atoms (single walled carbon nanotubes
and graphene) are promising materials in future electronic and
spintronics devices due to specific character of their electronic
structure. In this paper we present a comparative study of graphene
and single-wall carbon nanotubes by Raman spectro-microscopy in
strong magnetic field. This unique method allows to study changes in
electronic band structure of the two types of carbon nanostructures
induced by a strong magnetic field.
Abstract: This paper presents a hybrid three phase rectifier for
high power factor application. This rectifier is composed by zero
voltage transition (ZVT) and zero current transition (ZCT) boost
converter with three phase diode bridge rectifier, in parallel with a six
pulse three phase pulse width modulation (PWM) controlled rectifier.
The proposed topology is capable of high power factor with DC
output voltage regulation by providing sinusoidal input. Also, it
increases the overall efficiency of the new hybrid rectifier to 94.56%
and the total harmonic distortion of the hybrid structure varies from
0% to 16% at nominal output power. This topology was simulated in
MATLAB/SIMULINK environment and the output waveforms
presented with experimental result.
Abstract: In this paper, we have proposed a numerical method
for solving fuzzy Fredholm integral equation of the second kind. In
this method a combination of orthonormal Bernstein and Block-Pulse
functions are used. In most cases, the proposed method leads to
the exact solution. The advantages of this method are shown by an
example and calculate the error analysis.
Abstract: Frequent pattern mining is the process of finding a
pattern (a set of items, subsequences, substructures, etc.) that occurs
frequently in a data set. It was proposed in the context of frequent
itemsets and association rule mining. Frequent pattern mining is used
to find inherent regularities in data. What products were often
purchased together? Its applications include basket data analysis,
cross-marketing, catalog design, sale campaign analysis, Web log
(click stream) analysis, and DNA sequence analysis. However, one of
the bottlenecks of frequent itemset mining is that as the data increase
the amount of time and resources required to mining the data
increases at an exponential rate. In this investigation a new algorithm
is proposed which can be uses as a pre-processor for frequent itemset
mining. FASTER (FeAture SelecTion using Entropy and Rough sets)
is a hybrid pre-processor algorithm which utilizes entropy and roughsets
to carry out record reduction and feature (attribute) selection
respectively. FASTER for frequent itemset mining can produce a
speed up of 3.1 times when compared to original algorithm while
maintaining an accuracy of 71%.
Abstract: Three dimensional non-Interlaced carbon fibre
reinforced silicon carbide (3-D-Cf/SiC) composites with pyrocarbon
interphase were fabricated using isothermal chemical vapor
infiltration (ICVI) combined with polymer impregnation pyrolysis
(PIP) process. Polysilazane (PSZ) is used as a preceramic polymer to
obtain silicon carbide matrix. Thermo gravimetric analysis (TGA),
Infrared spectroscopic analysis (IR) and X-ray diffraction (XRD)
analysis were carried out on PSZ pyrolysed at different temperatures
to understand the pyrolysis and obtaining the optimum pyrolysing
condition to yield β-SiC phase. The density of the composites was
1.94 g cm-3 after the 3-D carbon preform was SiC infiltrated for 280 h
with one intermediate polysilazane pre-ceramic PIP process.
Mechanical properties of the composite materials were investigated
under tensile, flexural, shear and impact loading. The values of
tensile strength were 200 MPa at room temperature (RT) and 195
MPa at 500°C in air. The average RT flexural strength was 243 MPa.
The lower flexural strength of these composites is because of the
porosity. The fracture toughness obtained from single edge notched
beam (SENB) technique was 39 MPa.m1/2. The work of fracture
obtained from the load-displacement curve of SENB test was 22.8
kJ.m-2. The composites exhibited excellent impact resistance and the
dynamic fracture toughness of 44.8 kJ.m-2 is achieved as determined
from instrumented Charpy impact test. The shear strength of the
composite was 93 MPa, which is significantly higher compared 2-D
Cf/SiC composites. Microstructure evaluation of fracture surfaces
revealed the signatures of fracture processes and showed good
support for the higher toughness obtained.
Abstract: Application of hulls processing technologies, based on high-concentrated energy sources (laser and plasma technologies), allow improve shipbuilding production. It is typical for high-speed vessels construction using steel and aluminum alloys with high precision hulls required. Report describes high-performance technologies for plasma welding (using direct current of reversed polarity), laser, and hybrid laser-arc welding of hulls structures developed by JSC “SSTC”
Abstract: The emergence of the Semantic Web technology
increases day by day due to the rapid growth of multiple web pages.
Many standard formats are available to store the semantic web data.
The most popular format is the Resource Description Framework
(RDF). Querying large RDF graphs becomes a tedious procedure
with a vast increase in the amount of data. The problem of query
optimization becomes an issue in querying large RDF graphs.
Choosing the best query plan reduces the amount of query execution
time. To address this problem, nature inspired algorithms can be used
as an alternative to the traditional query optimization techniques. In
this research, the optimal query plan is generated by the proposed
SAPSO algorithm which is a hybrid of Simulated Annealing (SA)
and Particle Swarm Optimization (PSO) algorithms. The proposed
SAPSO algorithm has the ability to find the local optimistic result
and it avoids the problem of local minimum. Experiments were
performed on different datasets by changing the number of predicates
and the amount of data. The proposed algorithm gives improved
results compared to existing algorithms in terms of query execution
time.
Abstract: Artificial Neural Networks (ANN) trained using backpropagation
(BP) algorithm are commonly used for modeling
material behavior associated with non-linear, complex or unknown
interactions among the material constituents. Despite multidisciplinary
applications of back-propagation neural networks
(BPNN), the BP algorithm possesses the inherent drawback of
getting trapped in local minima and slowly converging to a global
optimum. The paper present a hybrid artificial neural networks and
genetic algorithm approach for modeling slump of ready mix
concrete based on its design mix constituents. Genetic algorithms
(GA) global search is employed for evolving the initial weights and
biases for training of neural networks, which are further fine tuned
using the BP algorithm. The study showed that, hybrid ANN-GA
model provided consistent predictions in comparison to commonly
used BPNN model. In comparison to BPNN model, the hybrid ANNGA
model was able to reach the desired performance goal quickly.
Apart from the modeling slump of ready mix concrete, the synaptic
weights of neural networks were harnessed for analyzing the relative
importance of concrete design mix constituents on the slump value.
The sand and water constituents of the concrete design mix were
found to exhibit maximum importance on the concrete slump value.