Abstract: This paper investigates the application of Particle Swarm Optimization (PSO) technique for coordinated design of a Power System Stabilizer (PSS) and a Thyristor Controlled Series Compensator (TCSC)-based controller to enhance the power system stability. The design problem of PSS and TCSC-based controllers is formulated as a time domain based optimization problem. PSO algorithm is employed to search for optimal controller parameters. By minimizing the time-domain based objective function, in which the deviation in the oscillatory rotor speed of the generator is involved; stability performance of the system is improved. To compare the capability of PSS and TCSC-based controller, both are designed independently first and then in a coordinated manner for individual and coordinated application. The proposed controllers are tested on a weakly connected power system. The eigenvalue analysis and non-linear simulation results are presented to show the effectiveness of the coordinated design approach over individual design. The simulation results show that the proposed controllers are effective in damping low frequency oscillations resulting from various small disturbances like change in mechanical power input and reference voltage setting.
Abstract: A direct adaptive controller for a class of unknown nonlinear discrete-time systems is presented in this article. The proposed controller is constructed by fuzzy rules emulated network (FREN). With its simple structure, the human knowledge about the plant is transferred to be if-then rules for setting the network. These adjustable parameters inside FREN are tuned by the learning mechanism with time varying step size or learning rate. The variation of learning rate is introduced by main theorem to improve the system performance and stabilization. Furthermore, the boundary of adjustable parameters is guaranteed through the on-line learning and membership functions properties. The validation of the theoretical findings is represented by some illustrated examples.
Abstract: This paper investigates the effects of knowledge-based acceleration feedback control integrated with Automatic Generation Control (AGC) to enhance the quality of frequency control of governing system. The Intelligent Acceleration Feedback Controller (IAFC) is proposed to counter the over and under frequency occurrences due to major load change in power system network. Therefore, generator tripping and load shedding operations can be reduced. Meanwhile, the integration of IAFC with AGC, a well known Load-Frequency Control (LFC) is essential to ensure the system frequency is restored to the nominal value. Computer simulations of frequency response of governing system are used to optimize the parameters of IAFC. As a result, there is substantial improvement on the LFC of governing system that employing the proposed control strategy.
Abstract: This paper focuses on a critical component of the situational awareness (SA), the neural control of depth flight of an autonomous underwater vehicle (AUV). Constant depth flight is a challenging but important task for AUVs to achieve high level of autonomy under adverse conditions. With the SA strategy, we proposed a multirate neural control of an AUV trajectory using neural network model reference controller for a nontrivial mid-small size AUV "r2D4" stochastic model. This control system has been demonstrated and evaluated by simulation of diving maneuvers using software package Simulink. From the simulation results it can be seen that the chosen AUV model is stable in the presence of high noise, and also can be concluded that the fast SA of similar AUV systems with economy in energy of batteries can be asserted during the underwater missions in search-and-rescue operations.
Abstract: The switching lag-time and the voltage drop across
the power devices cause serious waveform distortions and
fundamental voltage drop in pulse width-modulated inverter output.
These phenomenons are conspicuous when both the output frequency
and voltage are low. To estimate the output voltage from the PWM
reference signal it is essential to take account of these imperfections
and to correct them. In this paper, on-line compensation method is
presented. It needs three simple blocs to add at the ideal reference
voltages. This method does not require any additional hardware
circuit and off- line experimental measurement. The paper includes
experimental results to demonstrate the validity of the proposed
method. It is applied, finally, in case of indirect vector controlled
induction machine and implemented using dSpace card.
Abstract: We present a BeeBot, Binus Multi-client Intelligent Telepresence Robot, a custom-build robot system specifically designed for teleconference with multiple person using omni directional actuator. The robot is controlled using a computer networks, so the manager/supervisor can direct the robot to the intended person to start a discussion/inspection. People tracking and autonomous navigation are intelligent features of this robot. We build a web application for controlling the multi-client telepresence robot and open-source teleconference system used. Experimental result presented and we evaluated its performance.
Abstract: Preparation of size controlled nano-particles of silver catalyst on carbon substrate from e-waste has been investigated. Chemical route was developed by extraction of the metals available in nitric acid followed by treatment with hydrofluoric acid. Silver metal particles deposited with an average size 4-10 nm. A stabilizer concentration of 10- 40 g/l was used. The average size of the prepared silver decreased with increase of the anode current density. Size uniformity of the silver nano-particles was improved distinctly at higher current density no more than 20mA... Grain size increased with EK time whereby aggregation of particles was observed after 6 h of reaction.. The chemical method involves adsorption of silver nitrate on the carbon substrate. Adsorbed silver ions were directly reduced to metal particles using hydrazine hydrate. Another alternative method is by treatment with ammonia followed by heating the carbon loaded-silver hydroxide at 980°C. The product was characterized with the help of XRD, XRF, ICP, SEM and TEM techniques.
Abstract: Springback is a significant problem in the sheet metal
forming process. When the tools are released after the stage of
forming, the product springs out, because of the action of the internal
stresses. In many cases the deviation of form is too large and the
compensation of the springback is necessary. The precise prediction
of the springback of product is increasingly significant for the design
of the tools and for compensation because of the higher ratio of the
yield stress to the elastic modulus.
The main object in this paper was to study the effect of the
anisotropy on the springback for three directions of rolling: 0°, 45°
and 90°. At the same time, we highlighted the influence of three
different metallic materials: Aluminum, Steel and Galvanized steel.
The original of our purpose consist on tests which are ensured by
adapting a U-type stretching-bending device on a tensile testing
machine, where we studied and quantified the variation of the
springback according to the direction of rolling. We also showed the
role of lubrication in the reduction of the springback.
Moreover, in this work, we have studied important characteristics
in deep drawing process which is a springback. We have presented
defaults that are showed in this process and many parameters
influenced a springback.
Finally, our results works lead us to understand the influence of
grains orientation with different metallic materials on the springback
and drawing some conclusions how to concept deep drawing tools. In
addition, the conducted work represents a fundamental contribution
in the discussion the industry application.
Abstract: This paper presents a solution for the behavioural
animation of autonomous virtual agent navigation in virtual environments.
We focus on using Dempster-Shafer-s Theory of Evidence
in developing visual sensor for virtual agent. The role of the visual
sensor is to capture the information about the virtual environment
or identifie which part of an obstacle can be seen from the position
of the virtual agent. This information is require for vitual agent to
coordinate navigation in virtual environment. The virual agent uses
fuzzy controller as a navigation system and Fuzzy α - level for
the action selection method. The result clearly demonstrates the path
produced is reasonably smooth even though there is some sharp turn
and also still not diverted too far from the potential shortest path.
This had indicated the benefit of our method, where more reliable
and accurate paths produced during navigation task.
Abstract: This paper deals with the design of a periodic output
feedback controller for a flexible beam structure modeled with
Timoshenko beam theory, Finite Element Method, State space
methods and embedded piezoelectrics concept. The first 3 modes are
considered in modeling the beam. The main objective of this work is
to control the vibrations of the beam when subjected to an external
force. Shear piezoelectric sensors and actuators are embedded into
the top and bottom layers of a flexible aluminum beam structure, thus
making it intelligent and self-adaptive. The composite beam is
divided into 5 finite elements and the control actuator is placed at
finite element position 1, whereas the sensor is varied from position 2
to 5, i.e., from the nearby fixed end to the free end. 4 state space
SISO models are thus developed. Periodic Output Feedback (POF)
Controllers are designed for the 4 SISO models of the same plant to
control the flexural vibrations. The effect of placing the sensor at
different locations on the beam is observed and the performance of
the controller is evaluated for vibration control. Conclusions are
finally drawn.
Abstract: This paper presents three-phase evolution search methodology to automatically design fuzzy logic controllers (FLCs) that can work in a wide range of operating conditions. These include varying load, parameter variations, and unknown external disturbances. The three-phase scheme consists of an exploration phase, an exploitation phase and a robustness phase. The first two phases search for FLC with high accuracy performances while the last phase aims at obtaining FLC providing the best compromise between the accuracy and robustness performances. Simulations were performed for direct-drive two-axis robot arm. The evolved FLC with the proposed design technique found to provide a very satisfactory performance under the wide range of operation conditions and to overcome problem associated with coupling and nonlinearities characteristics inherent to robot arms.
Abstract: The three-species food web model proposed and investigated by Gakkhar and Naji is known to have chaotic behaviour for a choice of parameters. An attempt has been made to synchronize the chaos in the model using bidirectional coupling. Numerical simulations are presented to demonstrate the effectiveness and feasibility of the analytical results. Numerical results show that for higher value of coupling strength, chaotic synchronization is achieved. Chaos can be controlled to achieve stable synchronization in natural systems.
Abstract: Two optimized strategies were successfully established
to develop biomolecule-based magnetic nanoassemblies.
Streptavidin-coated and amine-coated magnetic nanoparticles were
chosen as model scaffolds onto which double-stranded DNA and
human immunoglobulin G were specifically conjugated in succession,
using biotin-streptavidin interaction or covalent cross-linkers. The
success of this study opens the prospect of developing selective and
sensitive nanoparticle-based structures for diagnostics or drug
delivery.
Abstract: Use of a sliding joint is an effective method to
decrease the stress in foundation structure where there is a horizontal
deformation of subsoil (areas afflicted with underground mining) or
horizontal deformation of a foundation structure (pre-stressed
foundations, creep, shrinkage, temperature deformation). A
convenient material for a sliding joint is a bitumen asphalt belt.
Experiments for different types of bitumen belts were undertaken at
the Faculty of Civil Engineering - VSB Technical University of
Ostrava in 2008. This year an extension of the 2008 experiments is in
progress and the shear resistance of a slide joint is being tested as a
function of temperature in a temperature controlled room. In this
paper experimental results of temperature dependant shear resistance
are presented. The result of the experiments should be the sliding
joint shear resistance as a function of deformation velocity and
temperature. This relationship is used for numerical analysis of
stress/strain relation between foundation structure and subsoil. Using
a rheological slide joint could lead to a decrease of the reinforcement
amount, and contribute to higher reliability of foundation structure
and thus enable design of more durable and sustainable building
structures.
Abstract: In this paper a simple terrain evaluation method for
hexapod robot is introduced. This method is based on feet coordinate
evaluation when all are on the ground. Depending on the feet
coordinate differences the local terrain evaluation is possible. Terrain
evaluation is necessary for right gait selection and/or body position
correction. For terrain roughness evaluation three planes are plotted:
two of them as definition points use opposite feet coordinates, third
coincides with the robot body plane. The leaning angle of body plane
is evaluated measuring gravity force using three-axis accelerometer.
Terrain roughness evaluation method is based on angle estimation
between normal vectors of these planes. Aim of this work is to
present a simple method for embedded robot controller, allowing to
find the best further movement settings.
Abstract: In this paper a comprehensive model of a fossil fueled
power plant (FFPP) is developed in order to evaluate the
performance of a newly designed turbine follower controller.
Considering the drawbacks of previous works, an overall model is
developed to minimize the error between each subsystem model
output and the experimental data obtained at the actual power plant.
The developed model is organized in two main subsystems namely;
Boiler and Turbine. Considering each FFPP subsystem
characteristics, different modeling approaches are developed. For
economizer, evaporator, superheater and reheater, first order models
are determined based on principles of mass and energy conservation.
Simulations verify the accuracy of the developed models. Due to the
nonlinear characteristics of attemperator, a new model, based on a
genetic-fuzzy systems utilizing Pittsburgh approach is developed
showing a promising performance vis-à-vis those derived with other
methods like ANFIS. The optimization constraints are handled
utilizing penalty functions. The effect of increasing the number of
rules and membership functions on the performance of the proposed
model is also studied and evaluated. The turbine model is developed
based on the equation of adiabatic expansion. Parameters of all
evaluated models are tuned by means of evolutionary algorithms.
Based on the developed model a fuzzy PI controller is developed. It
is then successfully implemented in the turbine follower control
strategy of the plant. In this control strategy instead of keeping
control parameters constant, they are adjusted on-line with regard to
the error and the error rate. It is shown that the response of the
system improves significantly. It is also shown that fuel consumption
decreases considerably.
Abstract: In this work, a new approach is proposed to control
the manipulators for Humanoid robot. The kinematics of the
manipulators in terms of joint positions, velocity, acceleration and
torque of each joint is computed using the Denavit Hardenberg (D-H)
notations. These variables are used to design the manipulator control
system, which has been proposed in this work. In view of supporting
the development of a controller, a simulation of the manipulator is
designed for Humanoid robot. This simulation is developed through
the use of the Virtual Reality Toolbox and Simulink in Matlab. The
Virtual Reality Toolbox in Matlab provides the interfacing and
controls to an environment which is developed based on the Virtual
Reality Modeling Language (VRML). Chains of bones were used to
represent the robot.
Abstract: Single crystals of Magnesium alloys such as pure Mg,
Mg-1Zn-0.5Y, Mg-0.1Y, and Mg-0.1Ce alloys were successfully
fabricated in this study by employing the modified Bridgman method.
To determine the exact orientation of crystals, pole figure
measurement using X-ray diffraction were carried out on each single
crystal. Hardness and compression tests were conducted followed by
subsequent recrysatllization annealing. Recrystallization kinetics of
Mg alloy single crystals has been investigated. Fabricated single
crystals were cut into rectangular shaped specimen and solution
treated at 400oC for 24 hrs, and then deformed in compression mode
by 30% reduction. Annealing treatment for recrystallization has been
conducted on these cold-rolled plates at temperatures of 300oC for
various times from 1 to 20 mins. The microstructure observation and
hardness measurement conducted on the recrystallized specimens
revealed that static recrystallization of ternary alloy single crystal was
very slow, while recrystallization behavior of binary alloy single
crystals appeared to be very fast.
Abstract: The motion planning technique described in this paper has been developed to eliminate or reduce the residual vibrations of belt-driven rotary platforms, while maintaining unchanged the motion time and the total angular displacement of the platform. The proposed approach is based on a suitable choice of the motion command given to the servomotor that drives the mechanical device; this command is defined by some numerical coefficients which determine the shape of the displacement, velocity and acceleration profiles. Using a numerical optimization technique, these coefficients can be changed without altering the continuity conditions imposed on the displacement and its time derivatives at the initial and final time instants. The proposed technique can be easily and quickly implemented on an actual device, since it requires only a simple modification of the motion command profile mapped in the memory of the electronic motion controller.
Abstract: This paper presents an automated inspection algorithm
for a thick plate. Thick plates typically have various types of surface
defects, such as scabs, scratches, and roller marks. These defects have
individual characteristics including brightness and shape. Therefore, it
is not simple to detect all the defects. In order to solve these problems
and to detect defects more effectively, we propose a dual light
switching lighting method and a defect detection algorithm based on
Gabor filters.