Abstract: Multiple-input multiple-output (MIMO) radar has
received increasing attention in recent years. MIMO radar has many
advantages over conventional phased array radar such as target
detection,resolution enhancement, and interference suppression. In
this paper, the results are presented from a simulation study of MIMO
uniformly-spaced linear array (ULA) antennas. The performance is
investigated under varied parameters, including varied array size,
pseudo random (PN) sequence length, number of snapshots, and
signal to noise ratio (SNR). The results of MIMO are compared to a
traditional array antenna.
Abstract: The localization information is crucial for the
operation of WSN. There are principally two types of localization
algorithms. The Range-based localization algorithm has strict
requirements on hardware, thus is expensive to be implemented in
practice. The Range-free localization algorithm reduces the hardware
cost. However, it can only achieve high accuracy in ideal scenarios.
In this paper, we locate unknown nodes by incorporating the
advantages of these two types of methods. The proposed algorithm
makes the unknown nodes select the nearest anchor using the
Received Signal Strength Indicator (RSSI) and choose two other
anchors which are the most accurate to achieve the estimated
location. Our algorithm improves the localization accuracy compared
with previous algorithms, which has been demonstrated by the
simulating results.
Abstract: The use of Flexible AC Transmission System
(FACTS) devices in a power system can potentially overcome
limitations of the present mechanically controlled transmission
system. Also, the advance of technology makes possible to include
new energy storage devices in the electrical power system. The
integration of Superconducting Magnetic Energy Storage (SMES)
into Static Synchronous Compensator (STATCOM) can lead to
increase their flexibility in improvement of power system dynamic
behaviour by exchanging both active and reactive powers with power
grids. This paper describes structure and behaviour of SMES,
specifications and performance principles of the STATCOM/SMES
compensator. Moreover, the benefits and effectiveness of integrated
SMES with STATCOM in power systems is presented. Also, the
performance of the STATCOM/SMES compensator is evaluated
using an IEEE 3-bus system through the dynamic simulation by
PSCAD/EMTDC software.
Abstract: In addition to the advantages of light weight, resistant
corrosion and ease of processing, aluminum is also applied to the
long-span spatial structures. However, the elastic modulus of
aluminum is lower than that of the steel. This paper combines the
high performance aluminum honeycomb panel with the aluminum
latticed shell, forming a new panel-and-rod composite shell structure.
Through comparative analysis between the static and dynamic
performance, the conclusion that the structure of composite shell is
noticeably superior to the structure combined before.
Abstract: In this communication, a low-cost circularly
polarized wire antenna exhibiting improved gain performance for
Dedicated Short Range Communications (DSRC), vehicle-to-vehicle
(V2V) and vehicle-to-infrastructure (V2I) communications is
presented. The proposed antenna comprises a Y-shaped quarterwavelength
monopole antenna surrounded by two iterations of eight
conductive arched walls acting as parasitic elements to enhance the
overall antenna gain and to shape the radiation pattern in the H-plane.
A hemispherical radome shell is added to protect the antenna
structure and its effect on the antenna performance is discussed. The
designed antenna demonstrates antenna gain of 8.2 dB with
omnidirectional far-field radiation pattern in the H-plane. The gain of
the proposed antenna is also compared with the characteristic of the
stand-alone Y-shaped monopole to highlight the advantages of the
proposed approach.
Abstract: This paper presents a power control for a Doubly Fed
Induction Generator (DFIG) using in Wind Energy Conversion
System (WECS) connected to the grid. The proposed control strategy
employs two nonlinear controllers, Backstipping (BSC) and slidingmode
controller (SMC) scheme to directly calculate the required
rotor control voltage so as to eliminate the instantaneous errors of
active and reactive powers. In this paper the advantages of BSC and
SMC are presented, the performance and robustness of this two
controller’s strategy are compared between them. First, we present a
model of wind turbine and DFIG machine, then a synthesis of the
controllers and their application in the DFIG power control.
Simulation results on a 1.5MW grid-connected DFIG system are
provided by MATLAB/Simulink.
Abstract: This paper introduces a boost converter with a new
active snubber cell. In this circuit, all of the semiconductor
components in the converter softly turns on and turns off with the
help of the active snubber cell. Compared to the other converters, the
proposed converter has advantages of size, number of components
and cost. The main feature of proposed converter is that the extra
voltage stresses do not occur on the main switches and main diodes.
Also, the current stress on the main switch is acceptable level.
Moreover, the proposed converter can operates under light load
conditions and wide input line voltage. In this study, the operating
principle of the proposed converter is presented and its operation is
verified with the Proteus simulation software for a 1 kW and 100 kHz
model.
Abstract: In the cooperative transmission scheme, both the
cellular system and broadcasting system are composed. Two cellular
base stations (CBSs) communicating with a user in the cell edge use
cooperative transmission scheme in the conventional scheme. In the
case that the distance between two CBSs and the user is distant, the
conventional scheme does not guarantee the quality of the
communication because the channel condition is bad. Therefore, if the
distance between CBSs and a user is distant, the performance of the
conventional scheme is decreased. Also, the bad channel condition has
bad effects on the performance. The proposed scheme uses two relays
to communicate well with CBSs when the channel condition between
CBSs and the user is poor. Using the relay in the high attenuation
environment can obtain both advantages of the high bit error rate
(BER) and throughput performance.
Abstract: In Electric Power Steering (EPS), spoke type
Brushless AC (BLAC) motors offer distinct advantages over other
electric motor types in terms torque smoothness, reliability and
efficiency. This paper deals with the shape optimization of spoke
type BLAC motor, in order to reduce cogging torque. This paper
examines 3 steps skewing rotor angle, optimizing rotor core edge and
rotor overlap length for reducing cogging torque in spoke type BLAC
motor. The methods were applied to existing machine designs and
their performance was calculated using finite- element analysis
(FEA). Prototypes of the machine designs were constructed and
experimental results obtained. It is shown that the FEA predicted the
cogging torque to be nearly reduce using those methods.
Abstract: A knowledge base stores facts and rules about the
world that applications can use for the purpose of reasoning. By
applying the concept of granular computing to a knowledge base,
several advantages emerge. These can be harnessed by applications
to improve their capabilities and performance. In this paper, the
concept behind such a construct, called a granular knowledge cube,
is defined, and its intended use as an instrument that manages to
cope with different data types and detect knowledge domains is
elaborated. Furthermore, the underlying architecture, consisting of the
three layers of the storing, representing, and structuring of knowledge,
is described. Finally, benefits as well as challenges of deploying it
are listed alongside application types that could profit from having
such an enhanced knowledge base.
Abstract: This paper presents the design and fabrication of a
novel piezoelectric actuator for a gas micro pump with check valve
having the advantages of miniature size, light weight and low power
consumption. The micro pump is designed to have eight major
components, namely a stainless steel upper cover layer, a piezoelectric
actuator, a stainless steel diaphragm, a PDMS chamber layer, two
stainless steel channel layers with two valve seats, a PDMS check
valve layer with two cantilever-type check valves and an acrylic
substrate. A prototype of the gas micro pump, with a size of 52 mm ×
50 mm × 5.0 mm, is fabricated by precise manufacturing. This device
is designed to pump gases with the capability of performing the
self-priming and bubble-tolerant work mode by maximizing the stroke
volume of the membrane as well as the compression ratio via
minimization of the dead volume of the micro pump chamber and
channel. By experiment apparatus setup, we can get the real-time
values of the flow rate of micro pump and the displacement of the
piezoelectric actuator, simultaneously. The gas micro pump obtained
higher output performance under the sinusoidal waveform of 250 Vpp.
The micro pump achieved the maximum pumping rates of 1185
ml/min and back pressure of 7.14 kPa at the corresponding frequency
of 120 and 50 Hz.
Abstract: Neural activity in the human brain starts from the
early stages of prenatal development. This activity or signals
generated by the brain are electrical in nature and represent not only
the brain function but also the status of the whole body. At the
present moment, three methods can record functional and
physiological changes within the brain with high temporal resolution
of neuronal interactions at the network level: the
electroencephalogram (EEG), the magnet oencephalogram (MEG),
and functional magnetic resonance imaging (fMRI); each of these has
advantages and shortcomings. EEG recording with a large number of
electrodes is now feasible in clinical practice. Multichannel EEG
recorded from the scalp surface provides very valuable but indirect
information about the source distribution. However, deep electrode
measurements yield more reliable information about the source
locations intracranial recordings and scalp EEG are used with the
source imaging techniques to determine the locations and strengths of
the epileptic activity. As a source localization method, Low
Resolution Electro-Magnetic Tomography (LORETA) is solved for
the realistic geometry based on both forward methods, the Boundary
Element Method (BEM) and the Finite Difference Method (FDM). In
this paper, we review the findings EEG- LORETA about epilepsy.
Abstract: Since 1920, the industry has almost completely
changed the rivets production techniques for the manufacture of
permanent welding join production of structures and manufacture of
other products. The welding arc is the process more widely used in
industries. This is accomplished by the heat of an electric arc which
melts the base metal while the molten metal droplets are transferred
through the arc to the welding pool, protected from the atmosphere
by a gas curtain. The GMAW (Gas metal arc welding) process is
influenced by variables such as: current, polarity, welding speed,
electrode: extension, position, moving direction; type of joint,
welder's ability, among others. It is remarkable that the knowledge
and control of these variables are essential for obtaining satisfactory
quality welds, knowing that are interconnected so that changes in one
of them requiring changes in one or more of the other to produce the
desired results. The optimum values are affected by the type of base
metal, the electrode composition, the welding position and the quality
requirements. Thus, this paper proposes a new methodology, adding
the variable vibration through a mechanism developed for GMAW
welding, in order to improve the mechanical and metallurgical
properties which does not affect the ability of the welder and enables
repeatability of the welds made. For confirmation metallographic
analysis and mechanical tests were made.
Abstract: There have been rigorous research and development
of unmanned aerial vehicles in the field of search and rescue (SAR)
operation recently. UAVs reduce unnecessary human risks while
assisting rescue efforts through aerial imagery, topographic mapping
and emergency delivery. The application of UAVs in offshore and
nearshore marine SAR missions is discussed in this paper. Projects
that integrate UAV technology into their systems are introduced to
highlight the great advantages and capabilities of UAVs. Scenarios
where UAVs could provide invaluable assistance are also suggested.
Abstract: Elastomeric polymer foam has been used widely in
the automotive industry, especially for isolating unwanted vibrations.
Such material is able to absorb unwanted vibration due to its
combination of elastic and viscous properties. However, the ‘creep
effect’, poor stress distribution and susceptibility to high
temperatures are the main disadvantages of such a system.
In this study, improvements in the performance of elastomeric
foam as a vibration isolator were investigated using the concept of
Foam Filled Fluid (FFFluid). In FFFluid devices, the foam takes the
form of capsule shapes, and is mixed with viscous fluid, while the
mixture is contained in a closed vessel. When the FFFluid isolator is
affected by vibrations, energy is absorbed, due to the elastic strain of
the foam. As the foam is compressed, there is also movement of the
fluid, which contributes to further energy absorption as the fluid
shears. Also, and dependent on the design adopted, the packaging
could also attenuate vibration through energy absorption via friction
and/or elastic strain.
The present study focuses on the advantages of the FFFluid
concept over the dry polymeric foam in the role of vibration isolation.
This comparative study between the performance of dry foam and the
FFFluid was made according to experimental procedures. The paper
concludes by evaluating the performance of the FFFluid isolator in
the suspension system of a light vehicle. One outcome of this
research is that the FFFluid may preferable over elastomer isolators
in certain applications, as it enables a reduction in the effects of high
temperatures and of ‘creep effects’, thereby increasing the reliability
and load distribution. The stiffness coefficient of the system has
increased about 60% by using an FFFluid sample. The technology
represented by the FFFluid is therefore considered by this research
suitable for application in the suspension system of a light vehicle.
Abstract: The literature on language teaching and second
language acquisition has been largely driven by monolingual
ideology with a common assumption that a second language (L2) is
best taught and learned in the L2 only. The current study challenges
this assumption by reporting learners' positive perceptions of tertiary
level teachers' code switching practices in Vietnam. The findings of
this study contribute to our understanding of code switching practices
in language classrooms from a learners' perspective.
Data were collected from student participants who were working
towards a Bachelor degree in English within the English for Business
Communication stream through the use of focus group interviews.
The literature has documented that this method of interviewing has a
number of distinct advantages over individual student interviews. For
instance, group interactions generated by focus groups create a more
natural environment than that of an individual interview because they
include a range of communicative processes in which each individual
may influence or be influenced by others - as they are in their real
life. The process of interaction provides the opportunity to obtain the
meanings and answers to a problem that are "socially constructed
rather than individually created" leading to the capture of real-life
data. The distinct feature of group interaction offered by this
technique makes it a powerful means of obtaining deeper and richer
data than those from individual interviews. The data generated
through this study were analysed using a constant comparative
approach. Overall, the students expressed positive views of this
practice indicating that it is a useful teaching strategy. Teacher code
switching was seen as a learning resource and a source supporting
language output. This practice was perceived to promote student
comprehension and to aid the learning of content and target language
knowledge. This practice was also believed to scaffold the students'
language production in different contexts. However, the students
indicated their preference for teacher code switching to be
constrained, as extensive use was believed to negatively impact on
their L2 learning and trigger cognitive reliance on the L1 for L2
learning. The students also perceived that when the L1 was used to a
great extent, their ability to develop as autonomous learners was
negatively impacted.
This study found that teacher code switching was supported in
certain contexts by learners, thus suggesting that there is a need for
the widespread assumption about the monolingual teaching approach
to be re-considered.
Abstract: This paper presents Carrier Sense Multiple Access
(CSMA) communication models based on SoC design methodology.
Such a model can be used to support the modeling of the complex
wireless communication systems. Therefore, the use of such
communication model is an important technique in the construction
of high-performance communication. SystemC has been chosen
because it provides a homogeneous design flow for complex designs
(i.e. SoC and IP-based design). We use a swarm system to validate
CSMA designed model and to show how advantages of incorporating
communication early in the design process. The wireless
communication created through the modeling of CSMA protocol that
can be used to achieve communication between all the agents and to
coordinate access to the shared medium (channel).
Abstract: This study, for its research subjects, uses patients who
had undergone total knee replacement surgery from the database of the
National Health Insurance Administration. Through the review of
literatures and the interviews with physicians, important factors are
selected after careful screening. Then using Cross Entropy Method,
Genetic Algorithm Logistic Regression, and Particle Swarm
Optimization, the weight of each factor is calculated and obtained. In
the meantime, Excel VBA and Case Based Reasoning are combined
and adopted to evaluate the system. Results show no significant
difference found through Genetic Algorithm Logistic Regression and
Particle Swarm Optimization with over 97% accuracy in both
methods. Both ROC areas are above 0.87. This study can provide
critical reference to medical personnel as clinical assessment to
effectively enhance medical care quality and efficiency, prevent
unnecessary waste, and provide practical advantages to resource
allocation to medical institutes.
Abstract: Biodiesel, as an alternative renewable fuel, has been
receiving increasing attention due to the limited supply of fossil fuels
and the increasing need for energy. Microalgae are promising source
for lipids, which can be converted to biodiesel. The biodiesel
production from microalgae lipids using lipase catalyzed reaction in
supercritical CO2 medium has several advantages over conventional
production processes. However, identifying the optimum microalgae
lipid extraction and transesterification conditions is still a challenge.
In this study, the quality of biodiesel produced from lipids extracted
from Scenedesmus sp. and their enzymatic transesterification using
supercritical carbon dioxide have been investigated. At the optimum
conditions, the highest biodiesel production yield was found to be
82%. The fuel properties of the produced biodiesel, without any
separation step, at optimum reaction condition, were determined and
compared to ASTM standards. The properties were found to comply
with the limits, and showed a low glycerol content, without any
separation step.
Abstract: This paper presents an application of a “Systematic
Soft Domain Driven Design Framework” as a soft systems approach
to domain-driven design of information systems development. The
framework use SSM as a guiding methodology within which we have
embedded a sequence of design tasks based on the UML leading to
the implementation of a software system using the Naked Objects
framework. This framework have been used in action research
projects that have involved the investigation and modelling of
business processes using object-oriented domain models and the
implementation of software systems based on those domain models.
Within this framework, Soft Systems Methodology (SSM) is used as
a guiding methodology to explore the problem situation and to
develop the domain model using UML for the given business
domain. The framework is proposed and evaluated in our previous
works, and a real case study “Information Retrieval System for
academic research” is used, in this paper, to show further practice and
evaluation of the framework in different business domain. We argue
that there are advantages from combining and using techniques from
different methodologies in this way for business domain modelling.
The framework is overviewed and justified as multimethodology
using Mingers multimethodology ideas.