Abstract: This article proposes a current-mode square-rooting
circuit using current follower transconductance amplifier (CTFA).
The amplitude of the output current can be electronically controlled
via input bias current with wide input dynamic range. The proposed
circuit consists of only single CFTA. Without any matching
conditions and external passive elements, the circuit is then
appropriate for an IC architecture. The magnitude of the output signal
is temperature-insensitive. The PSpice simulation results are
depicted, and the given results agree well with the theoretical
anticipation. The power consumption is approximately 1.96mW at
±1.5V supply voltages.
Abstract: Sedimentation in reservoirs lowers the quality of
consumed water, reduce the volume of reservoir, lowers the
controllable amount of flood, increases the risk of water overflow
during possible floods and the risk of reversal and reduction of dam's
useful life. So in all stages of dam establishment such as cognitive
studies, phase-1 studies of design, control, construction and
maintenance, the problem of sedimentation in reservoir should be
considered. What engineers need to do is examine and develop the
methods to keep effective capacity of a reservoir, however engineers
should also consider the influences of the methods on the flood
disaster, functions of water use facilities and environmental
issues.This article first examines the sedimentation in reservoirs and
shows how to control it and then discusses the studies about the
sedimens in Siazakh Dam.
Abstract: The 4G front-end transceiver needs a high
performance which can be obtained mainly with an optimal
architecture and a multi-band Local Oscillator. In this study, we
proposed and presented a new architecture of multi-band frequency
synthesizer based on an Inverse Sine Phase Detector Phase Locked
Loop (ISPD PLL) without any filters and any controlled gain block
and associated with adapted multi band LC tuned VCO using a
several numeric controlled capacitive branches but not binary
weighted. The proposed architecture, based on 0.35μm CMOS
process technology, supporting Multi-band GSM/DCS/DECT/
UMTS/WiMax application and gives a good performances: a phase
noise @1MHz -127dBc and a Factor Of Merit (FOM) @ 1MHz -
186dB and a wide band frequency range (from 0.83GHz to 3.5GHz),
that make the proposed architecture amenable for monolithic
integration and 4G multi-band application.
Abstract: Magnetic carbon nanotubes composites were obtained
by filling carbon nanotubes with paramagnetic iron oxide particles.
Detailed investigation of magnetic behaviour of resulting composites
was done at different temperatures. Measurements indicate that these
functionalized nanotubes are superparamagnetic at room temperature;
however, no superparamagnetism was observed at 125 K and 80 K.
The blocking temperature TB was estimated at 145 K. These magnetic
carbon nanotubes have the potential of being used in a wide range of
applications, in particular, the production of nanofluids, which can be
controlled and steered by appropriate magnetic fields.
Abstract: In this study, noise characteristics of structure were analyzed in an effort to reduce noise passing through an opening of an
enclosure surrounding the structure that generates noise. Enclosures
are essential measure to protect noise propagation from operating machinery. Access openings of the enclosures are important path of noise leakage. First, noise characteristics of structure were analyzed
and feed-forward noise control was performed using simulation in
order to reduce noise passing through the opening of enclosure, which
surrounds a structure generating noise. We then implemented a
feed-forward controller to actively control the acoustic power through
the opening. Finally, we conducted optimization of placement of the
reference sensors for several cases of the number of sensors. Good
control performances were achieved using the minimum number of microphones arranged an optimal placement.
Abstract: In this article, we synthesize a novel chitosan -based
superabsorbent hydrogel via graft copolymerization of mixtures
acrylic acid (AA) and N-vinyl pyrollidon onto chitosan backbones.
The polymerization reaction was carried out in an aqueous medium
and in the presence of ammonium persulfate (APS) as an initiator and
N,N'-methylene bisacrylamide (MBA) as a crosslinker.The hydrogel
structures were confirmed by FTIR spectroscopy. The swelling
behavior of these absorbent polymers was also investigated in
various salt solutions. Results indicated that the swelling capacity
decreased with an increase in the ionic strength of the swelling
medium. Furthermore, the swelling of superabsorbing hydrogels was
examined in solutions with pH values ranging between 1.0 and 13.0.
It showed a reversible pH-responsive behavior at pHs 2.0 and 8.0.
This on-off switching behavior makes the synthesized hydrogels as
an excellent candidate for controlled delivery of bioactive agents.
Abstract: There is inadequate information on the practice of
female genital mutilation (FGM) in the UK, and there are often
myths and perceptions within communities that influence the
effectiveness of prevention programmes. This means it is difficult to
address the trends and changes in the practice in the UK.
To this end, FORWARD undertook novel and innovative research
using the Participatory Ethnographic and Evaluative Research
(PEER) method to explore the views of women from Eritrea, Sudan,
Somalia and Ethiopia that live in London and Bristol (two UK cities).
Women-s views, taken from PEER interviews, reflected reasons for
continued practice of FGM: marriageability, the harnessing and
control of female sexuality, and upholding traditions from their
countries of origin. It was also clear that the main supporters of the
practice were believed to be older women within families and
communities.
Women described the impact FGM was having on their lives as
isolating. And although it was clearly considered a private and
personal matter, they developed a real sense of connection with their
peers within the research process.
The women were overwhelmingly positive about combating the
practice, although they believed it would probably take a while
before it ends completely. They also made concrete
recommendations on how to improve support services for women
affected by FGM: Training for professionals (particularly in
healthcare), increased engagement with, and outreach to,
communities, culturally appropriate materials and information made
available and accessible to communities, and more consequent
implementation of legislation.
Finally, the women asked for more empathy and understanding,
particularly from health professionals. Rather than presenting FGM
as a completely alien and inconceivable practice, it may help for
those looking into these women-s lives and working with them to
understand the social and economic context in which the practice
takes place.
Abstract: This paper describes the design concepts and
implementation of a 5-Joint mechanical arm for a rescue robot named
CEO Mission II. The multi-joint arm is a five degree of freedom
mechanical arm with a four bar linkage, which can be stretched to
125 cm. long. It is controlled by a teleoperator via the user-friendly
control and monitoring GUI program. With Inverse Kinematics
principle, we developed the method to control the servo angles of all
arm joints to get the desired tip position. By clicking the determined
tip position or dragging the tip of the mechanical arm on the
computer screen to the desired target point, the robot will compute
and move its multi-joint arm to the pose as seen on the GUI screen.
The angles of each joint are calculated and sent to all joint servos
simultaneously in order to move the mechanical arm to the desired
pose at once. The operator can also use a joystick to control the
movement of this mechanical arm and the locomotion of the robot.
Many sensors are installed at the tip of this mechanical arm for
surveillance from the high level and getting the vital signs of victims
easier and faster in the urban search and rescue tasks. It works very
effectively and easy to control. This mechanical arm and its software
were developed as a part of the CEO Mission II Rescue Robot that
won the First Runner Up award and the Best Technique award from
the Thailand Rescue Robot Championship 2006. It is a low cost,
simple, but functioning 5-Jiont mechanical arm which is built from
scratch, and controlled via wireless LAN 802.11b/g. This 5-Jiont
mechanical arm hardware concept and its software can also be used
as the basic mechatronics to many real applications.
Abstract: In this paper a novel, simple and reliable digital firing
scheme has been implemented for speed control of three-phase
induction motor using ac voltage controller. The system consists of
three-phase supply connected to the three-phase induction motor via
three triacs and its control circuit. The ac voltage controller has three
modes of operation depending on the shape of supply current. The
performance of the induction motor differs in each mode where the
speed is directly proportional with firing angle in two modes and
inversely in the third one. So, the control system has to detect the
current mode of operation to choose the correct firing angle of triacs.
Three sensors are used to feed the line currents to control system to
detect the mode of operation. The control strategy is implemented
using a low cost Xilinx Spartan-3E field programmable gate array
(FPGA) device. Three PI-controllers are designed on FPGA to
control the system in the three-modes. Simulation of the system is
carried out using PSIM computer program. The simulation results
show stable operation for different loading conditions especially in
mode 2/3. The simulation results have been compared with the
experimental results from laboratory prototype.
Abstract: Designing and implementing intelligent systems has become a crucial factor for the innovation and development of better products of space technologies. A neural network is a parallel system, capable of resolving paradigms that linear computing cannot. Field programmable gate array (FPGA) is a digital device that owns reprogrammable properties and robust flexibility. For the neural network based instrument prototype in real time application, conventional specific VLSI neural chip design suffers the limitation in time and cost. With low precision artificial neural network design, FPGAs have higher speed and smaller size for real time application than the VLSI and DSP chips. So, many researchers have made great efforts on the realization of neural network (NN) using FPGA technique. In this paper, an introduction of ANN and FPGA technique are briefly shown. Also, Hardware Description Language (VHDL) code has been proposed to implement ANNs as well as to present simulation results with floating point arithmetic. Synthesis results for ANN controller are developed using Precision RTL. Proposed VHDL implementation creates a flexible, fast method and high degree of parallelism for implementing ANN. The implementation of multi-layer NN using lookup table LUT reduces the resource utilization for implementation and time for execution.
Abstract: This paper addresses control of commutation of switched reluctance (SR) motor without the use of a physical position detector. Rotor position detection schemes for SR motor based on magnetisation characteristics of the motor use normal excitation or applied current /voltage pulses. The resulting schemes are referred to as passive or active methods respectively. The research effort is in realizing an economical sensorless SR rotor position detector that is accurate, reliable and robust to suit a particular application. An effective and reliable means of generating commutation signals of an SR motor based on inductance profile of its stator windings determined using active probing technique is presented. The scheme has been validated online using a 4-phase 8/6 SR motor and an 8-bit processor.
Abstract: The design of chaos-based secure communication
via synchronized modified Chua-s systems is investigated in
this paper. A continuous control law is proposed to ensure
synchronization of the master and slave modified Chua-s
systems by using the variable structure control technique.
Particularly, the concept of extended systems is introduced
such that a continuous control input is obtained to avoid
chattering phenomenon. Then, it becomes possible to ensure
that the message signal embedded in the transmitter can be
recovered in the receiver.
Abstract: This work investigated the steady state and dynamic
simulation of a fixed bed industrial naphtha reforming reactors. The
performance of the reactor was investigated using a heterogeneous
model. For process simulation, the differential equations are solved
using the 4th order Runge-Kutta method .The models were validated
against measured process data of an existing naphtha reforming plant.
The results of simulation in terms of components yields and
temperature of the outlet were in good agreement with empirical data.
The simple model displays a useful tool for dynamic simulation,
optimization and control of naphtha reforming.
Abstract: Classification is an interesting problem in functional
data analysis (FDA), because many science and application problems
end up with classification problems, such as recognition, prediction,
control, decision making, management, etc. As the high dimension
and high correlation in functional data (FD), it is a key problem to
extract features from FD whereas keeping its global characters, which
relates to the classification efficiency and precision to heavens. In this
paper, a novel automatic method which combined Genetic Algorithm
(GA) and classification algorithm to extract classification features is
proposed. In this method, the optimal features and classification model
are approached via evolutional study step by step. It is proved by
theory analysis and experiment test that this method has advantages in
improving classification efficiency, precision and robustness whereas
using less features and the dimension of extracted classification
features can be controlled.
Abstract: In this study, structural, mechanical, thermal and
electrical properties of poly (lactic acid) (PLA) nanocomposites with
low-loaded (0-1.5 wt%) untreated, heat and nitric acid treated multiwalled
carbon nanotubes (MWCNTs) were studied. Among the
composites, untreated 0.5 wt % MWCNTs and acid-treated 1.0 wt%
MWCNTs reinforced PLA show the tensile strength and modulus
values higher than the others. These two samples along with pure
PLA exhibit the stable orthorhombic α-form, whilst other samples
reveal the less stable orthorhombic β-form, as demonstrated by X-ray
diffraction study. Differential scanning calorimetry reveals the
evolution of the mentioned different phases by controlled cooling and
discloses an enhancement of PLA crystallization by nanotubes
incorporation. Thermogravimetric analysis shows that the MWCNTs
loaded sample degraded faster than PLA. Surface resistivity of the
nanocomposites is found to be dropped drastically by a factor of 1013
with a low loading of MWCNTs (1.5 wt%).
Abstract: Two-dimensional heat conduction within a composed solid material with a constant internal heat generation has been investigated numerically in a sector of the rotor a generator. The heat transfer between two adjacent materials is assumed to be purely conduction. Boundary conditions are assumed to be forced convection on the fluid side and adiabatic on symmetry lines. The control volume method is applied for the diffusion energy equation. Physical coordinates are transformed to the general curvilinear coordinates. Then by using a line-by-line method, the temperature distribution in a sector of the rotor has been determined. Finally, the results are normalized and the effect of cooling fluid on the maximum temperature of insulation is investigated.
Abstract: This paper introduces an adaptive control scheme to synchronize two identical Chua's systems. Introductory part of the paper is presented in the first part of the paper and then in the second part, a new theorem is proposed based on which an adaptive control scheme is developed to synchronize two identical modified Chua's circuit. Finally, numerical simulations are included to verify the effectiveness of the proposed control method.
Abstract: The main purpose of this research was to study how to
communicate the identity of the Amphawa district, Samut Songkram
province for sustainable tourism. The qualitative data was collected
through studying related materials, exploring the area, in-depth
interviews with three groups of people: three directly responsible
officers who were key informants of the district, twenty foreign
tourists and five Thai tourist guides. A content analysis was used to
analyze the qualitative data. The two main findings of the study were
as follows:
1. The identity of the Amphawa District, Samut Songkram
province is the area controlled by Amphawa sub district (submunicipality).
The working unit which runs and looks after
Amphawa sub district administration is known as the Amphawa
mayor. This establishment was built to be a resort for normal
people and tourists visiting the Amphawa district near the
Maekong River consisting of rest accommodations. Along the
river there is a restaurant where food and drinks are served, rich
mangrove forests, a learning center, fireflies and cork trees. The
Amphawa district was built to honor and commemorate King
Rama II and is where the greatest number of fireflies and cork
trees can be seen in Thailand from May to October each year.
2. The communication of the identity of Amphawa District, Samut
Songkram Province which the researcher could find and design
to present in English materials can be summed up in 5 items: 1)
The history of the Amphawa District, Samut Songkram province
2) The history of King Rama II Memorial Park 3) The identity of
Amphawa Floating Market 4) The Learning center of
Ecosystem: Fireflies and Cork Trees 5) How to keep Amphawa
District, Samut Songkram Province for sustainable tourism.
Abstract: The operating control parameters of injection
flushing type of electrical discharge machining process on stainless
steel 304 workpiece with copper tools are being optimized
according to its individual machining characteristic i.e. material
removal rate (MRR). Lower MRR during EDM machining process
may decrease its- machining productivity. Hence, the quality
characteristic for MRR is set to higher-the-better to achieve the
optimum machining productivity. Taguchi method has been used
for the construction, layout and analysis of the experiment for each
of the machining characteristic for the MRR. The use of Taguchi
method in the experiment saves a lot of time and cost of preparing
and machining the experiment samples. Therefore, an L18
Orthogonal array which was the fundamental component in the
statistical design of experiments has been used to plan the
experiments and Analysis of Variance (ANOVA) is used to
determine the optimum machining parameters for this machining
characteristic. The control parameters selected for this
optimization experiments are polarity, pulse on duration, discharge
current, discharge voltage, machining depth, machining diameter
and dielectric liquid pressure. The result had shown that the higher
the discharge voltage, the higher will be the MRR.
Abstract: The study attempted to identify the dominant
intelligences of athletes by comparing the developmental differences
of multiple intelligences between athletes and non-athletes. The
weekly specialized training hours and years of specialized training
was examined to see how it can predict the dominant intelligence with
the age factor controlled. There were 355 participants in the research
(202 athletes and 153 non-athletes). Collected data were analyzed with
one-way MANOVA and multiple hierarchical regression. The results
suggested the dominant intelligences of athletes were Interpersonal
Intelligence, Bodily-Kinesthetic Intelligence, and Intrapersonal
Intelligence. The weekly specialized training hours and years of
specialized training could effectively predict the Interpersonal
Intelligence, Bodily-Kinesthetic Intelligence, and Intrapersonal
Intelligence of athletes. The author suggested the future studies could
focus on the theory construction of weekly specialized training and
years of specialized training. Also, the studies on using “Bridge
strategy" by the athletes to guide disadvantage intelligences with
dominant intelligences are highly valued.