Showing papers presented at "International Conference on Electrical Engineering in 2007"

Encryption Efficiency Analysis and Security Evaluation of RC6 Block Cipher for Digital Images

Abstract: This paper investigates the encryption efficiency of RC6 block cipher application to digital images, introducing a mathematical measure for encryption efficiency, which we will call the encryption quality instead of visual inspection. The encryption quality of RC6 block cipher is investigated among its several design parameters such as word size, number of rounds, and secret key length and the optimal choices for the best values of such design parameters are given. Also, the security analysis of RC6 block cipher for digital images is investigated from strict cryptographic viewpoint. The security estimations of RC6 block cipher for digital images against brute-force, statistical, and differential attacks are explored. Experiments are made to test the security of RC6 block cipher for digital images against all aforementioned types of attacks. Experiments and results verify and prove that RC6 block cipher is highly secure for real-time image encryption from cryptographic viewpoint. Thorough experimental tests are carried out with detailed analysis, demonstrating the high security of RC6 block cipher algorithm. So, RC6 block cipher can be considered to be a real-time secure symmetric encryption for digital images.

Design of an Optimal Hybrid Energy System Model for Remote Rural Area Power Generation

Abstract: This paper deals with the design of a hybrid energy system consisting of wind, photovoltaic, biomass and small/micro hydro to supply continuous power to the load. A diesel generator is added to ensure continuous power supply and to take care of intermittent nature of wind and photovoltaic. The paper reports the results of optimization of hybrid energy system model of a remote area of Jaunpur block of Uttaranchal state of India. The model has been developed with the objective of minimizing cost function based on demand and potential constraints and optimized using computer programme developed in C++. The economic analysis has resulted in the calculation of capital cost, cost of energy for different types of resources and optimized cost of hybrid energy system. To consider the fluctuation in the discharge and power generation from SHP, the EPDF has been varied from 1.0 to 0.0. The EPDF is Electric Power Delivery Factor (also called optimizing power factor) has maximum value equal tol.

Logic Optimization for Majority Gate-Based Nanoelectronic Circuits Based on Genetic Algorithm

Abstract: In this paper we propose a novel and efficient method for majority gate-based design. The basic Boolean primitive in quantum cellular automata (QCA) is the majority gate. Method for reducing the number of majority gates required for computing Boolean functions is developed to facilitate the conversion of sum of products (SOP) expression into QCA majority logic. This method is based on genetic algorithm and can reduce the hardware requirements for a QCA design. We will show that the proposed approach is very efficient in deriving the simplified majority expression in QCA design.

Adaptive Segmentation Using Wavelet Transform

Abstract: In many applications analysis of nonstationary signals requires the signal to be segmented into piece-wise stationary epochs. Segmentation can be performed by splitting the signal at time instants of charge in the amplitude or frequency content of the signal. In this paper, the signal is decomposed into signals with different frequency bands using wavelet transform. The nonlinear energy operator is then applied on the decomposed signals, which combines the amplitude and frequency contents of the signal. The proposed technique is applied on synthetic signal and real EEG data to evaluate its performance on segmenting nonstationary signals. The results show that the proposed technique outperforms the recently published method in decomposing nonstationary signals.

Performance Comparison of DFT-OFDM and Wavelet-OFDM with Zero-Forcing Equalizer for FIR Channel Equalization

Abstract: In conventional DFT based orthogonal frequency division multiplexing (OFDM), cyclic prefix (CP) is used to avoid the inter symbol interference (ISI) caused by a time dispersive channel. A solution has been proposed in literature, which involves replacing DFT with wavelet packet transform (WPT) in communication systems. WPT does not require CP and has the attraction of having much lower side lobes. However, in wavelet based multicarrier systems, channel equalization remains an open research area. In this article, a time-domain zero-forcing equalizer (ZFE) for wavelet packet based OFDM (WOFDM) is proposed. The performance comparison of DFT-OFDM and WOFDM is given for an arbitrary FIR channel with different types of wavelet packets. Simulation results show improvement in bit error rate (BER) performance for WOFDM.

PR-MAC A Priority Reservation MAC Protocol For Wireless Sensor Networks

Abstract: Wireless sensor networks are very application specific and have to be developed according to the requirements of a particular problem. They are usually deployed in harsh and mobile environments, with tasks ranging from just collecting environment readings to highly crucial tasks like tracking an enemy vehicle. This means the sensor networks can monitor or sense a very wide range of parameters and tasks. However, all these measurements and events that are read by the sensors are never of equal importance. So we propose PR-MAC, which provides a scheme in which we prioritize the events that are being recognized. Our aim is to design a MAC layer protocol which would reduce the delay of transmitting high priority tasks or measurements.

Parameter Estimation Optimization Based on Genetic Algorithm Applied to DC Motor

Abstract: Thin paper proposed the application of genetic algorithm optimization in estimating the parameters of dynamic state of DC motor. LSE estimation is considered as a convenient method for parameter estimation, in comparison with this proposed method. Despite of LSE estimation that is based on the linearity of error function due to parameters, GA method can easily identify unknown parameters by minimizing the sum of squared errors. GA is imported in comparison with conventional optimization methods because of its power in searching entire solution space with more probability of finding the global optimum. Also the model can be nonlinear with respect to parameters, and in this identification free noise system is assumed and transient excitation is considered instead of persistent excitation. Finally comparison between LSE and GA optimization is presented to indicate robustness and resolution of GA identification method in parameter estimation.

A New Moduli Set for Residue Number System: {rn 2,rn 1,rn}

Abstract: In this paper a new moduli set {rn -2,rn -1,rn} is introduced where r = 2k + 1 and k= 1,2,3,... . This moduli set includes pair wise relatively prime moduli, so it offers the maximum possible dynamic range. For this moduli set, the related circuits are simply realized in the Multiple Valued Logic (MVL) and arithmetic in this moduli set enjoys very high speed operations and simple reverse/forward conversion (RNS to MVL/MVL to RNS). After introducing the new moduli set, we design its related circuits and converters. Finally, we compare the results to those of similar moduli sets and show that our moduli set significantly improves the time complexity while offers greater dynamic range.

Effect of Nonlinear Load Distributions on Total Harmonic Distortion in a Power System

Abstract: The increased use of solid state devices at the consumer end has introduced a power quality issue in the form of harmonic distortion due to their nonlinear nature. The magnitude of this harmonic distortion varies with the nonlinear load distribution at various voltage levels of a system. This paper presents a detailed analysis of harmonic distortion in terms of THD for various load combinations in a power system. The trends in THD variations are obtained at various operating conditions. The effect of introducing nonlinear loads at various voltage levels of a system is discussed. The effect of harmonic model of nonlinear load in terms of variation of THD at different buses and the degradation effects of these harmonic distortions are also presented.

A Proposed Preventive Information Security System

Abstract: Managing computer and network security programs has become an increasingly difficult and challenging job. Dramatic advances in computing and communications technology during the past few years have redirected the focus of data processing from the computing center to the terminals in individual offices and homes. The result is that managers must now monitor security on a more widely dispersed level. These changes are continuing to accelerate, making the security manager's job increasingly difficult. In this paper a better solution for Information Security management has been proposed by designing PrISM (Preventive Information Security Management). PrISM aims to develop and deploy an indigenous Information Security Management System (ISMS) with intrusion prevention capabilities. The objective is to develop an ISMS with appropriate security assurance controls and risk handling processes. This will provide best protection of critical assets against information warfare attacks. The task has been planned by performing reverse engineering of Open Source Security Information Management (OSSIM) system. A detailed discussion on OSSIM and commercially available software Event Horizon has also been presented.

Bayesian Learning for Software Architecture Recovery

Abstract: Understanding a software system at the architectural level is especially important when the system is to be adapted to meet changing requirements. However, architectural documentation is often unavailable or out-of-date. In this paper, we explore the use of Bayesian learning methods for automatic recovery of a software system's architecture, given incomplete or out-of-date documentation. We employ software modules with known classifications to train the Naive Bayes Classifier. We then use the classifier to place new instances, i.e. new software modules, into appropriate sub-systems. We evaluate the performance of the classifier by conducting experiments on a software system, and compare the results obtained with a manually prepared architecture. We present an analysis of the results, and also discuss the assumptions under which the results are expected to be meaningful.

Analysis of TSR-based SVC for a Three-Phase System with Static and Dynamic Loads

Abstract: In this paper, the effect of the thyristor switched reactor-based static VAr compensator (SVC), which is one of flexible AC transmission systems (FACTS) controllers, to load voltages has been proposed in the three-phase system at static load and dynamic load conditions. The design and testing of TS R-based SVC are verified using the MATLAB/Simulink 7.04reg and Power Systems Toolbox. The results show that significant improvement on reactive power compensation and bus voltage regulation could be achieved by using the TSR-based SVC. Also, harmonic levels generated by TSR-based SVC do not cause to instability in the test system.

Comparing Wave Propagation Characteristics of MV XLPE Cable and Covered-Conductor Overhead Line using Time Domain Reflectometry Technique

Abstract: In this paper, the wave propagation characteristics of single-phase medium voltage (MV) cross-linked polyethylene (XLPE) cable are determined using time domain reflectometry (TDR) measurement technique. TDR delivers the complex propagation constant (attenuation and phase constants) of lossy cable transmission line as a function of frequency. The frequency-dependent propagation velocity is also determined from the TDR measurements through the parameters extraction procedure. The TDR measurement results for MV XLPE cable and covered-conductor (CC) overhead line are compared and it is proved that CC line has lower attenuation and higher propagation velocity than power cable. The measurement results can be used to localize the discontinuities in XLPE power cables and for PD detection to monitor falling trees on the MV CC overhead lines.

Reed Solomon coded PPM for Terrestrial FSO Links

Abstract: Free space optical communications (FSO) are fast emerging as the most promising approach for addressing the emerging broadband access network and its "last mile" bottleneck. However, atmospheric attenuations and weather dependence remain the major hurdle in the wide scale acceptability of the technology. This paper proposes performance enhancement using higher state modulation schemes (i.e. 16 and 256-PPM) which promises a gain upto 25 dB when combined with RS codes as compared to the current widely used 2 state modulation mechanisms. The "RS-coded PPM" is shown as an extremely robust and well performing coded-modulation scheme for future FSO systems using a novel approach to terrestrial FSO channel modeling.

Design and Development of Magnetic Torque Couplers and Magnetic Gears

Abstract: New breed of permanent magnets are increasingly being used in novel permanent magnet electromechanical devices. This paper deals with the application of rare-earth magnets in the design of synchronous magnetic torque couplers and magnet gears. The performance of experimental devices is compared with finite element analysis.

Character Recognition Using Mathematical Morphology

Abstract: The automatic recognition of characters dates back to several decades, the reason being the large diversity of applications which make valuable use of recognition techniques. This paper proposes the recognition of a set of handwritten digits using mathematical morphology. Certain features that can be used to clearly distinguish one digit from the other are extracted. A decision tree has been developed to aid in the classification process. At each node a morphological operation is applied on the incoming digit, and the results dictate what the next step in the sequence should be. The method has been applied on a large sample collected from a diverse set of individuals. The recognition rates achieved are appreciable and substantially support the techniques discussed.

Soft Starting of an Induction Motor using Adaptive Neuro Fuzzy Inference System

Abstract: Induction motors are used in industry in variety of applications such as blowers, fans, compressors, pumps, mixers, crushers and grinders etc. Soft starters, involving voltage controllers, are used for starting and speed adjustment of induction motors. This paper presents a neural network based soft starter which controls the speed by the adjustment of firing angles of thyristors. The suggested technique eliminates the starting torque pulsations by triggering the back to back connected thyristors. The control strategy is implemented using microcontrollers and neural networks and performance analysis of the system is carried out with the help of hybrid model of induction motor. The results obtained are satisfactory and promising. The advantage of such a soft starter is its simplicity, stability and high accuracy as compared to the conventional soft starter which uses mathematical calculations of firing angle which is a complex and time consuming task especially in on-line control applications.

Dynamic Priority Based Message Scheduling on Controller Area Network

Abstract: Controller area network (CAN) is a serial communication protocol developed in early 1980's by Robert Bosch. Low cost, ease of use and ability to work in harsh EMI environments have resulted in its widespread acceptance in automotive and automation industry. Message scheduling and access to the bus in CAN is performed through a fixed Message Identifier field, which is also the basis for a static priority. Although this fixed priority apparently results in good bus utilization but low priority messages may suffer from starvation due to an ill designed message identifier allocation scheme. Also with its introduction into newer fields, the fixed priority per message is looking to be a limitation for some applications. Un till now there has been no work to add this faculty to CAN in a standardize way. This paper presents a set of algorithms and guide lines to support the dynamically changing priorities in a CAN network without breaking the integration with existing CAN based networks. The scheme is effectively a generalization of the single priority per message to a multi-priority-window per message.

Analysis of Blackout of National Grid System of Pakistan in 2006 and the Application of PSS and FACTS Controllers as Remedial Measures

Abstract: On 24th September, 2006, a severe disturbance occurred on the National Grid System of Pakistan which caused cascading outages of transmission lines and generating stations that ultimately led to system wide collapse/blackout. This major blackout was one of the worst power system failures of WAPDA, the main electric utility of Pakistan. This paper provides an insight of the investigations to identify system constraints that caused blackout The bulk power transfer on long 500 kV transmission lines in northern part of WAPDA, prior to blackout, had already loaded them close to their stability limits. As a result, the system, after a disturbance, was stressed further beyond its capability and experienced small signal and voltage instabilities, which led to its collapse. In this paper, detailed analytical work including steady state and dynamic simulations/analyses have been carried out to study the behaviour of VVAPDA power system during collapse. Later, the effectiveness of the power system controllers, i.e., power system stabilizers (PSS) and flexible AC transmission system (FACTS) has been demonstrated as remedial measures to prevent such major system blackout.

Low-Power High-Performance and Dynamically Configured Multi-Port Cache Memory Architecture

Abstract: As on-chip cache size has increased considerably in recent high-performance microprocessor technologies, power dissipation and leakage current in SRAM have become critical. High-performance IC designs use multi-port cache memory to provide the needed accessibility and bandwidth. Since the word and bit lines cover the foot-print of the entire cache section, duplicating the word and bit lines for multiple ports results in large silicon area and increases bitline discharge and power dissipation. As technology scales down device size and supply voltages, static power dissipation has emerged as a critical factor in total system power dissipation. In this paper, we present an area-and energy-efficient multi-port cache memory architecture, which employs isolation nodes, local sense amplifiers and dynamic memory partitioning techniques, to facilitate simultaneous multi-port accesses without duplicating bitlines. The proposed cache memory architecture also reduces bitline latency.

Efficient Training Data Reduction for SVM based Handwritten Digits Recognition

Abstract: Support vector machine (SVM) are binary classifiers that make any two classes linearly separable by finding a maximum-margin hyper-plane between the data samples of the two classes in a given feature space. Once the discrimination function of this hyper-plane has been found during the training stage, any unknown sample can be classified by checking the sign of this discrimination function for the unknown sample. It is well understood in SVM theory that the equation of SVM discrimination function is largely determined by data points close to the decision boundary. These data points close to the decision boundary are called as support vectors (SV). SVM training process for large data sets is often a time consuming process. Hence reducing the original data to contain only the SVs is a useful goal for speeding up the training process. This reduction of training data should not affect the accuracy of SVM classifier. In this paper, we propose an efficient training data reduction algorithm (Peer-SV) for SVM classifiers. The algorithm is based on the observation that the desired support vectors are those data points which are of opposite classes and whose diametric sphere does not contain any other class instance of the two classes. We have found these SVs in an efficient way i.e. computing the SVs between the peer classes only and removing the farthest points earlier to retain the border points. The algorithm has been tested on handwritten digits data sets. The results obtained on the total data and on the reduced data shows the accuracy of the adopted approach.

Rotor Position Detection in SRM Drive Utilizing Phase Shift Variations in a Formed Resonant Circuit

Abstract: In switched reluctance motors, each individual phase excitation must be synchronized with the rotor position which necessitates the need for a position sensing scheme. This paper presents a complete and novel method to indirectly detect the rotor position at standstill and also at low speeds in switched reluctance motor. The method utilizes current phase variation technique in conjunction with the use of resonant scheme. A circuit consists of an external resistance R, motor phase inductance, L (thetas), and an external capacitance, C is formed and fed by a sinusoidal voltage having the same resonant frequency as the circuit. The current flowing through the resistor has the same frequency as the input voltage but can have different phase shift when compared to the input voltage due to die variation of phase inductance, L(thetas) which is directly proportional to rotor position. The produced resistor voltage waveform is then compared to the input sinusoidal voltage waveform in order to obtain a pulse width proportional to the position of the rotor. The width of the pulse is determined accordance to the phase inductance which is directly proportional to the rotor position. Finally, the paper presents the results obtained which demonstrates the feasibility and practicability of the method and outlines the advantages of this method.

Lp-stability analysis of a class of nonlinear fractional differential equations

Abstract: —This paper investigates the Lp-stability properties of fractional nonlinear differential equations. Systems defined on a finite time interval are considered. The principal contributions are summarized in a theorem which give suffient conditions for bounded stability of fractional order systems. We show that the proposed results can not be extended to the case of systems defined on an infinite time interval.

IP Address Space Management using Aggregated Fixed Length Subnet Masking

Abstract: In this paper we have proposed a new technique of subnetting for class C IP addresses to minimize the wastage of address space. Different techniques such as Fixed Length Subnet Masking (FLSM) and Variable length Subnet Masking (VLSM) are discussed and a new technique, Aggregated Fixed Length Subnet Masking (AFLSM) is proposed. The discussion is concluded with the comparison of these techniques and it is shown that our technique yields minimum address space wastage.

A Novel C-Band Single Diode Mixer with Ultra High LO/RF and LO/IF Isolation

Abstract: A novel single diode mixer with ultra high LO/RF, LO/IF isolation and having a reasonably good conversion loss has been designed. RF and LO signals are applied through bandpass and lowpass filters respectively. The mixer operates in C-Band and downconverts a Hock of frequencies (5.925 GHz -6.425 GHz) to a block of frequencies (3.7 GHz - 4.2 GHz) using a fixed frequency local oscillator at 2.225 GHz. The proposed mixer structure achieves double balanced functionality with a single diode and obviates the need for RF and LO baluns. The measured conversion loss ranges from 8 -10 dB and port isolations are in excess of 60 dB.

FACTS Control Devices (Statcom, SSSC and UPFC) Re-Configuration Techniques By PSIM/MATLAB

Abstract: This paper discusses comprehensively the dynamic performance of the FACTS control devices in multiple operations, hardware needed to complement the simulated models. This paper also presents the schematic and basic control of reconfigurable FACTS devices to realize the major voltage source converter FACTS Topologies: SATCOM, SSSC (Static synchronous Series compensator), UPFC. Furthermore, these control paradigms proposed in three prompt strategic directions to overcome outdated conventional control and other power control flaws in Pakistan power utilities wherein, including our neighboring countries (Iran, KSA, and India), and world-at-large, the FACTS been installed and in operation successfully. Whereas, Pakistan desperately needs this technology to hedge its power utilities to meet forthcoming challenges in power industry likewise significant growth in industry as well as domestic users under the declaration of government electrifying Pakistan 2007 to tap out power to its all rural areas by undertaking all possible means. Henceforth, the FACTS technology is an instrumental solution which will play vital and viable role to make this decree possible in following streams in parallel: Set-up FACTS Laboratory at UET to develop prototype devices, FACTS feasibility study and a pilot project (at most contaminated area). This paper also culminates and enlists all three experiment results to encourage the elective/graduate course in electric power system.

A Directional Multiscale Approach for Speckle Reduction in Optical Coherence Tomography Images

Abstract: This paper presents a new directional Bayesian despeckling technique for optical coherence tomography (OCT) images in the complex wavelet domain, which reduces speckle while preserving the detailed features and textural information. It has been shown that wavelet coefficients of natural images have significantly non-Gaussian statistics that are best described by families of heavy-tailed distributions. On the other hand, most of the edge information of layer boundaries in OCT images is located in the same direction. For these directional images, the use of heavy-tailed distributions does not seem to be appropriate for all wavelet decomposition subbands. So wavelet coefficients of the subbands which have almost the same orientation as the original image are modeled with heavy-tailed distributions such as the Cauchy, while the others are modeled with a simple Gaussian distribution. Within this framework, we design a maximum a posteriori estimator to remove speckle from noisy coefficients. Better results are obtained when we use the dual-tree complex wavelet transform which offers improved directional selectivity and near shift invariance property. Our results show that the proposed scheme outperforms some existing despeckling methods.

Model-Predicted Induction Motor Behaviour under Different Operating Conditions

Abstract: This paper presents a simulation study to verify the capability of the instantaneous phase variation (IPV) for the detection of broken rotor bar faults in a squirrel cage induction motor. The three-phase squirrel cage motor model has been derived using a multi coupled circuits approach. The obtained results show that IPV has a good detection and diagnosis capabilities especially at full load conditions.

Fuzzy Logic Based Speed Control of a Permanent Magnet Brushless DC Motor Drive

Abstract: This paper presents an analysis by which the dynamic performances of a permanent magnet brushless DC (PMBLDC) motor drive with different speed controllers can be successfully predicted. The control structure of the proposed drive system is described The dynamics of the drive system with a classical proportional-integral (PI) and a fuzzy-logic (FL) speed controllers are presented. The simulation result; for different parameters and operation modes of the drive system are investigated and compared The results with FL speed controller show improvement in transient response of the PMBLDC drive over conventional PI controller. Moreover, useful conclusions stemmed from such a study which is thought of good use and valuable for users of these controllers.

Effect of Group Size on Anycasting with Receiver Base Forwarding in Delay Tolerant Networks

Abstract: Delay/disruption tolerant networks (DTNs) are known for frequent and long duration partitions and end-to-end connectivity may be absent between the source and the destination. Anycast service is used for applications such as information exchange in hazards/crisis situation, recourse discovery, etc in Delay Tolerant Networks. For a specific type of DTN, where the mobile nodes are sparsely distributed, communicating via low radio range experience frequent and long duration partition and end-to-end path may not be present at the time of message generation. We have proposed a Receiver Based Forwarding (RBF) scheme for anycasting in DTN, which considers the path length as well as the number of receivers in forwarding the anycast bundle to the next hop Group size plays an important role in DTN anycasting, the group size varies in different scenarios. In this paper we have studied the effect of group size on our proposed Anycasting protocol by varying the group size from 3 to 15. Our simulation results have shown that the RBF performs better than the normal forwarding (NF) in term of data delivery ratio, average end-to-end delay and overall data efficiency because the probability of available receivers increases.