IJISA Vol. 5, No. 10, Sep. 2013
Cover page and Table of Contents: PDF (size: 203KB)
REGULAR PAPERS
Many techniques are used for Transient Stability assessment (TSA) of synchronous generators encompassing traditional time domain state numerical integration, Lyapunov based methods, probabilistic approaches and Artificial Intelligence (AI) techniques like pattern recognition and artificial neural networks.
This paper examines another two proposed artificial intelligence techniques to tackle the transient stability problem. The first technique is based on the Inductive Inference Reasoning (IIR) approach which belongs to a particular family of machine learning from examples. The second presents a simple fuzzy logic classifier system for TSA. Not only steady state but transient attributes are used for transient stability estimation so as to reflect machine dynamics and network changes due to faults.
The two techniques are tested on a standard test power system. The performance evaluation demonstrated satisfactory results in early detection of machine instability. The advantage of the two techniques is that they are straightforward and simple for on-line implementation.
The Zinc modelling language provides a rich set of constraints, data structures and expressions to support high-level modelling. Zinc is the only modelling language that supports all solving techniques: constraint programming, mathematical methods, and local search. By providing search patterns, it allows users to implement their search methods in a declarative way. There are currently three search patterns implemented in Zinc: backtracking search, branch and bound search, and local search. In this paper we explain how Zinc efficiently implements user-defined local search algorithms.
[...] Read more.Thanks to globalization, mobile devices have become an inseparable entity of our daily life. We often expect our smart devices (mobile phone, tablet, portable media player) to possess the functionalities of a personal computer. As the technology is getting cheaper, owning multiple mobile devices, each for a specific purpose, is becoming the current trend. For instance, an Android smartphone to fulfill a user’s communication needs on-the-go, an iPad could serve the user’s reading hobby, and lastly, a laptop for productivity activities. As such, to switch among different devices could be the emerging problem of the current generation. With our proposed Android based remote control app, a user does not only able to control his Windows based office laptop, but he could access to his IOS based devices too. Besides click event and text input, this application also supports panning and zooming gesture inputs.
[...] Read more.This paper proposes an efficient differential evolution (DE) algorithm for the solution of the optimal reactive power dispatch (ORPD) problem. The main objective of ORPD is to minimize the total active power loss with optimal setting of control variables. The continuous control variables are generator bus voltage magnitudes. The discrete control variables are transformer tap settings and reactive power of shunt compensators. In DE algorithm the other form of differential mutation operator is used. It consists to add the global best individual in the differential mutation operator to improve the solution. The DE algorithm solution has been tested on the standard IEEE 30-Bus test system to minimize the total active power loss without and with voltage profile improvement. The results have been compared to the other heuristic methods such as standard genetic algorithm and particle swarm optimization method. Finally, simulation results show that this method converges to better solutions.
[...] Read more.A state-of-the-art-technology was used to design the unbalanced three phase motor controller. The fluctuation of line voltage has been questioned in recent times due to the use of heavy powered machine with three phases. This paper is focused on deriving a control scheme to drive a three phase motor that could be used in industry or households. The very simple circuitry has been employed in this design. To do this, extensive MATLAB analysis and PSpice software was conducted in order to optimize the control system and finally the results are practically verified.
[...] Read more.In this article, we would like to revisit the existing definitions of cartesian product of fuzzy sets and the fuzzy relational matrix from the standpoint of the new definition of fuzzy sets on the basis of reference function. In the process it is observed that there are drawbacks in the current defintions and hence new definitions of terms mentioned are proposed in this article. Some numerical examples are also presented to make the matter clear and simple.
[...] Read more.When a microgrid and distributed generation resources are disconnected from the grid for protection reasons, the restoration of microgrid (restoring distributed generation resources to feed the loads in microgrid) causes to increase the reliability of microgrid. When a fault occurs in the main grid, the reliability of islanded microgrid will be increased. In this paper a novel method for restoration of the microgrid is proposed when the fault occurred in the main grid. Therefore, we can take advantage of selling power energy during the fault. In addition, because of increasing in reliability, the price of energy will be increased. This paper selected a microgrid with two type of distributed generation resources, power electronic based distributed generation and small gas turbine with synchronous generator. Another purpose of this paper is to reduce restoration time. The proposed algorithm for automatic switching time is provided. This paper selected a microgrid system in medium voltage. The limitation voltage and frequency is according to IEEE 1547 standards, and simulation will be done by EMTP-RV with automatic and constant time switching separately.
[...] Read more.One of the power amplifiers linearization technique is linear amplification with nonlinear components (LINC).The effects of phase and gain imbalances between two signal branches in LINC transmitters have been analyzed in this paper. Then a feedback path has been added to compensate this mismatches, using two complex gain in each path.This complex gains are controlled in a way to calibrate any gain and phase mismatches between two path using Modified Gradient Algorithm (MGA) adaptively. The main advantages of this algorithm over other algorithms are zero residual error and fast convergence time. In the proposedarchitecture power amplifiers in each path are modeled as a complex gain which its phase and amplitude depend on input signal level. Many simulations have been performed to validate the proposed self calibrating LINC transmitter. Simulation results have confirmed the analyticalpredictions. According to simulation results the proposed structure has around 40 dB/Hz improvement in the first adjacent channel of the output signal spectrum.
[...] Read more.Distinct sleep phases are related to different dynamical patterns in electroencephalogram (EEG) signals. In this article, the relationship between the sleep stages and nonlinear behavior of sleep EEG is explored. In particular, analysis of approximate entropy (ApEn) and the largest Lyapunov exponent is evaluated in patients with sleep apnea, which is defined as respiratory flow that is suspended or decreased for more than 10 s. The pathological sleep EEG signals for analysis were obtained from the MIT-BIH polysomnography database available online at the PhysioBank. The results show that for the both normal and apneic sleep epochs, ApEn decreased significantly as the sleep goes into deeper stages. Therefore, it indicated that as sleep becomes deeper, the brain function becomes less activated. Compared with normal sleep, the mean value of largest lyapunov exponents was also significantly lower than that of normal epochs during deep sleep stages. The results also show that the average largest lyapunov exponents of EEG signals increased in the REM state. Because during this stage of sleep, the cortex becomes more active and more neurons incorporate in the information processing. In conclusion, the nonlinear dynamical measures obtained from the nonlinear dynamical analysis such as the approximate entropy and largest lyapunov exponents can be useful for characterizing the physiological or pathological states of the brain.
[...] Read more.Electronic passports (e-passports) are to prevent the illegal entry of traveller into a specific country and limit the use of counterfeit documents by more accurate identification of an individual. The e-passport, as it is sometimes called, represents a bold initiative in the deployment of two new technologies: cryptography security and biometrics (face, fingerprints, palm prints and iris). A passport contains the important personal information of holder such as photo, name, date of birth and place, nationality, date of issue, date of expiry, authority and so on. The goal of the adoption of the electronic passport is not only to expedite processing at border crossings, but also to increase security. The paper explores the privacy and security implications of this impending worldwide experiment in biometrics authentication technology.
[...] Read more.A modern and well established education system is a backbone of any nation’s success. High reputation in international platform can only be achieved when best and deserving students represent your country and earn reputation on their ability and dedication. For this purpose an education system must be a cheating free system so that non-deserving students should not get the positions which they don’t deserve. This research aims to develop such a system which can be used in exam halls to avoid the cheating based on student’s eye movement. The algorithm detects the human from the scene followed by the face detection and recognition. The next phase involves eye detection followed by eye's movement tracking to analyze and decide about whether the student is involved in cheating or not. The system can be used on a large scale in educational institutions as well as in corporate sector wherever exams have been conducted.
[...] Read more.The increasing demand for multi-degree-of-freedom (DOF) continuum robot in presence of highly nonlinear dynamic parameters in a number of industries has motivated a flurry of research in the development of soft computing nonlinear methodology. This robot is capable of providing smooth and isotropic three-dimensional motion in each joint. Compared to conventional robotic manipulators that offer the same motion capabilities, the innovative spherical motor possesses several advantages. Not only can the spherical motor combine 3-DOF motion in a single joint, it has a large range of motion with no singularities in its workspace. This research contributes to the on-going research effort by exploring alternate methods for controlling the continuum robot manipulator. This research addresses two basic issues related to the control of a continuum robots; (1) a more accurate representation of the dynamic model of an existing prototype, and (2) the design of a robust feedback controller. The robust backstepping controller proposed in this research is used to further demonstrate the appealing features exhibited by the continuum robot. Robust feedback controller is used to position control of continuum robot in presence of uncertainties. Using Lyapunov type stability arguments, a robust backstepping controller is designed to achieve this objective. The controller developed in this research is designed in two steps. Firstly, a robust stabilizing torque is designed for the nominal continuum robot dynamics derived using the constrained Lagrangian formulation. Next, the fuzzy logic methodology applied to it to solution uncertainty problem. The fuzzy model free problem is formulated to minimize the nonlinear formulation of continuum robot. The eventual stability of the controller depends on the torque generating capabilities of the continuum robots.
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