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: This paper presents the design process of a high
performance 3-phase 3.7 kW 2-pole line start permanent magnet
synchronous motor for pumping system. A method was proposed to
study the starting torque characteristics considering line start with
high inertia load. A d-q model including cage was built to study the
synchronization capability. Time-stepping finite element method
analysis was utilized to accurately predict the dynamic and transient
performance, efficiency, starting current, speed curve and etc.
Considering the load torque of pumps during starting stage, the rotor
bar was designed with minimum demagnetization of permanent
magnet caused by huge starting current.
Abstract: The present study aimed to investigate the effect of
synchronous music in Gymnastics' motor skill performance among
undergraduate female students in physical education college at Basra
University. The researcher used experimental design. 20 female
students of physical education divided equally into two groups, (10)
experimental group with music, (10) control group without music.
All participants complete 6 weeks in testing. Data analysis based on
T-test shows significant difference at (α = 0.05) in all skills level
between experimental and control groups in favor of experimental
group. Results of this study contribute to developing the role of
synchronous music in improving gymnastic skills performance.
Abstract: In this paper, an experiment was conducted to assess
the impact of online deliberation on citizens’ attitudes. Specifically,
this research compared pre and post deliberation opinions of
participants who deliberated online via an asynchronous platform
regarding the issue of political opinion polls. Results indicate that
online deliberation had a positive effect on citizens’ attitudes since it
was found that following deliberation participants changed their
views regarding public opinion polls. Specifically, online deliberation
improved discussants perceptions regarding the reliability of polls,
while suppressing their negative views about the misuse of polls by
media, polling organizations and politicians.
Abstract: We used live E. coli containing synthetic genetic
oscillators to study how the degree of synchrony between the genetic
circuits of sister cells changes with temperature. We found that both
the mean and the variability of the degree of synchrony between the
fluorescence signals from sister cells are affected by temperature.
Also, while most pairs of sister cells were found to be highly
synchronous in each condition, the number of asynchronous pairs
increased with increasing temperature, which was found to be due to
disruptions in the oscillations. Finally we provide evidence that these
disruptions tend to affect multiple generations as opposed to
individual cells. These findings provide insight in how to design
more robust synthetic circuits and in how cell division can affect their
dynamics.
Abstract: Fast speed drives for Permanent Magnet Synchronous
Motor (PMSM) is a crucial performance for the electric traction
systems. In this paper, PMSM is derived with a Model-based
Predictive Control (MPC) technique. Fast speed tracking is achieved
through optimization of the DC source utilization using MPC. The
technique is based on predicting the optimum voltage vector applied
to the driver. Control technique is investigated by comparing to the
cascaded PI control based on Space Vector Pulse Width Modulation
(SVPWM). MPC and SVPWM-based FOC are implemented with the
TMS320F2812 DSP and its power driver circuits. The designed MPC
for a PMSM drive is experimentally validated on a laboratory test
bench. The performances are compared with those obtained by a
conventional PI-based system in order to highlight the improvements,
especially regarding speed tracking response.
Abstract: Among various active filters, shunt active filter is a
viable solution for reactive power and harmonics compensation. In
this paper, the SRF plan is used to generate current reference for
compensation and conventional PI controllers were used as the
controller to compensate the reactive power. The design of the closed
loop controllers is reserved simple by modeling them as first order
systems. Computationally uncomplicated and efficient SVM system
is used in the present work for better utilization of dc bus voltage.
The rating of shunt active filter has been finalized based on the
reactive power demand of the selected reactive load. The proposed
control and SVM technique are validated by simulating in MATLAB
software.
Abstract: The distribution of a single global clock across a chip
has become the major design bottleneck for high performance VLSI
systems owing to the power dissipation, process variability and multicycle
cross-chip signaling. A Network-on-Chip (NoC) architecture
partitioned into several synchronous blocks has become a promising
approach for attaining fine-grain power management at the system
level. In a NoC architecture the communication between the blocks is
handled asynchronously. To interface these blocks on a chip
operating at different frequencies, an asynchronous FIFO interface is
inevitable. However, these asynchronous FIFOs are not required if
adjacent blocks belong to the same clock domain. In this paper, we
have designed and analyzed a 16-bit asynchronous micropipelined
FIFO of depth four, with the awareness of place and route on an
FPGA device. We have used a commercially available Spartan 3
device and designed a high speed implementation of the
asynchronous 4-phase micropipeline. The asynchronous FIFO
implemented on the FPGA device shows 76 Mb/s throughput and a
handshake cycle of 109 ns for write and 101.3 ns for read at the
simulation under the worst case operating conditions (voltage =
0.95V) on a working chip at the room temperature.
Abstract: This work deals with parameter identification of
permanent magnet motors, a class of ac motor which is particularly
important in industrial automation due to characteristics like
applications high performance, are very attractive for applications
with limited space and reducing the need to eliminate because they
have reduced size and volume and can operate in a wide speed range,
without independent ventilation. By using experimental data and
genetic algorithm we have been able to extract values for both the
motor inductance and the electromechanical coupling constant, which
are then compared to measured and/or expected values.
Abstract: The aim of this study was to design and simulate a
particular type of Asynchronous State Machine (ASM), namely a
‘traffic light controller’ (TLC), operated at a frequency of 0.5 Hz.
The design task involved two main stages: firstly, designing a 4-bit
binary counter using J-K flip flops as the timing signal and,
subsequently, attaining the digital logic by deploying ASM design
process. The TLC was designed such that it showed a sequence of
three different colours, i.e. red, yellow and green, corresponding to
set thresholds by deploying the least number of AND, OR and NOT
gates possible. The software Multisim was deployed to design such
circuit and simulate it for circuit troubleshooting in order for it to
display the output sequence of the three different colours on the
traffic light in the correct order. A clock signal, an asynchronous 4-
bit binary counter that was designed through the use of J-K flip flops
along with an ASM were used to complete this sequence, which was
programmed to be repeated indefinitely. Eventually, the circuit was
debugged and optimized, thus displaying the correct waveforms of
the three outputs through the logic analyser. However, hazards
occurred when the frequency was increased to 10 MHz. This was
attributed to delays in the feedback being too high.
Abstract: The idea of the asynchronous transmission in
wavelength division multiplexing (WDM) ring MANs is studied in
this paper. Especially, we present an efficient access technique to
coordinate the collisions-free transmission of the variable sizes of IP
traffic in WDM ring core networks. Each node is equipped with a
tunable transmitter and a tunable receiver. In this way, all the
wavelengths are exploited for both transmission and reception. In
order to evaluate the performance measures of average throughput,
queuing delay and packet dropping probability at the buffers, a
simulation model that assumes symmetric access rights among the
nodes is developed based on Poisson statistics. Extensive numerical
results show that the proposed protocol achieves apart from high
bandwidth exploitation for a wide range of offered load, fairness of
queuing delay and dropping events among the different packets size
categories.
Abstract: Web-based Cognitive Writing Instruction (WeCWI)’s
contribution towards language development can be divided into
linguistic and non-linguistic perspectives. In linguistic perspective,
WeCWI focuses on the literacy and language discoveries, while the
cognitive and psychological discoveries are the hubs in non-linguistic
perspective. In linguistic perspective, WeCWI draws attention to free
reading and enterprises, which are supported by the language
acquisition theories. Besides, the adoption of process genre approach
as a hybrid guided writing approach fosters literacy development.
Literacy and language developments are interconnected in the
communication process; hence, WeCWI encourages meaningful
discussion based on the interactionist theory that involves input,
negotiation, output, and interactional feedback. Rooted in the elearning
interaction-based model, WeCWI promotes online
discussion via synchronous and asynchronous communications,
which allows interactions happened among the learners, instructor,
and digital content. In non-linguistic perspective, WeCWI highlights
on the contribution of reading, discussion, and writing towards
cognitive development. Based on the inquiry models, learners’
critical thinking is fostered during information exploration process
through interaction and questioning. Lastly, to lower writing anxiety,
WeCWI develops the instructional tool with supportive features to
facilitate the writing process. To bring a positive user experience to
the learner, WeCWI aims to create the instructional tool with
different interface designs based on two different types of perceptual
learning style.
Abstract: Today’s modern interconnected power system is
highly complex in nature. In this, one of the most important
requirements during the operation of the electric power system is the
reliability and security. Power and frequency oscillation damping
mechanism improve the reliability. Because of power system
stabilizer (PSS) low speed response against of major fault such as
three phase short circuit, FACTs devise that can control the network
condition in very fast time, are becoming popular. But FACTs
capability can be seen in a major fault present when nonlinear models
of FACTs devise and power system equipment are applied. To realize
this aim, the model of multi-machine power system with FACTs
controller is developed in MATLAB/SIMULINK using Sim Power
System (SPS) blockiest. Among the FACTs device, Static
synchronous series compensator (SSSC) due to high speed changes
its reactance characteristic inductive to capacitive, is effective power
flow controller. Tuning process of controller parameter can be
performed using different method. But Genetic Algorithm (GA)
ability tends to use it in controller parameter tuning process. In this
paper firstly POD controller is used to power oscillation damping.
But in this station, frequency oscillation dos not has proper damping
situation. So FOD controller that is tuned using GA is using that
cause to damp out frequency oscillation properly and power
oscillation damping has suitable situation.
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: There are a variety of reference current identification
methods, for the shunt active power filter (SAPF), such as the
instantaneous active and reactive power, the instantaneous active and
reactive current and the synchronous detection method are evaluated
and compared under ideal, non sinusoidal and unbalanced voltage
conditions. The SAPF performances, for the investigated
identification methods, are tested for a non linear load. The
simulation results, using Matlab Power System Blockset Toolbox
from a complete structure, are presented and discussed.
Abstract: The asynchronous discussion forum is one of the most
widely used activities in learning management system environment.
Online forum allows participants to interact, construct knowledge,
and can be used to complement face to face sessions in blended
learning courses. However, to what extent do the students perceive
the benefits or advantages of forum remain to be seen. Through
content and social network analyses, instructors will be able to gauge
the students’ engagement and knowledge construction level. Thus,
this study aims to analyze the students’ level of knowledge
construction and their participation level that occur through online
discussion. It also attempts to investigate the relationship between the
level of knowledge construction and their social interaction patterns.
The sample involves 23 students undertaking a master course in one
public university in Malaysia. The asynchronous discussion forum
was conducted for three weeks as part of the course requirement. The
finding indicates that the level of knowledge construction is quite
low. Also, the density value of 0.11 indicating the overall
communication among the participants in the forum is low. This
study reveals that strong and significant correlations between SNA
measures (in-degree centrality, out-degree centrality) and level of
knowledge construction. Thus, allocating these active students in
different group aids the interactive discussion takes place. Finally,
based upon the findings, some recommendations to increase students’
level of knowledge construction and also for further research are
proposed.
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: The article presents the concept of an electromagnetic
circuit generator with permanent magnets mounted on the surface
rotor core designed for single phase work. Computation field-circuit
model was shown. The spectrum of time course of voltages in the
idle work was presented. The cross section with graphically
presentation of magnetic induction in particular parts of
electromagnetic circuits was presented. Distribution of magnetic
induction at the rated load point for each phase was shown. The time
course of voltages and currents for each phases for rated power were
displayed. An analysis of laboratory results and measurement of load
characteristics of the generator was discussed. The work deals with
three electromagnetic circuits of generators with permanent magnet
where output voltage characteristics versus rated power were
expressed.
Abstract: The use of permanent magnets (PM) is increasing in
permanent magnet synchronous machines (PMSM) to fulfill the
requirements of high efficiency machines in modern industry. PMSM
are widely used in industrial applications, wind power plants and the
automotive industry. Since PMSM are used in different
environmental conditions, the long-term effect of NdFeB-based
magnets at high temperatures and their corrosion behavior have to be
studied due to the irreversible loss of magnetic properties.
In this paper, the effect of magnetic properties due to corrosion
and increasing temperature in a climatic chamber has been presented.
The magnetic moment and magnetic field of the magnets were
studied experimentally.
Abstract: In this paper the vibration of a synchronous belt drive
during start-up is analyzed and discussed. Besides considering the
belt elasticity, the model here proposed also takes into consideration
the electromagnetic response of the DC motor. The solution of the
motion equations is obtained by means of the modal analysis in
state space, which allows to obtain the decoupling of all equations,
without introducing the hypothesis of proportional damping. The
mathematical model of the transmission and the solution algorithms
have been implemented within a computing software that allows the
user to simulate the dynamics of the system and to evaluate the effects
due to the elasticity of the belt branches and to the electromagnetic
behavior of the DC motor. In order to show the details of the
calculation procedure, the paper presents a case study developed with
the aid of the above-mentioned software.