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VOLUME 7
NUMBER 2
SUMMER-FALL  2008 

Table of Contents


Editorial Note


Impact of TCPAR on Cluster-based Congestion Management Using Improved Performance Index

A. Kumar, S. C. Srivastava, and S. N. Singh

PP. 89-97

A Comparison of Various Hybrid Elliptical Antenna Arrays

R. A. Sadeghzadeh, A. A. Lotfi Neyestanak, M. Naser-Moghadasi, and M. Ghiamy

PP. 98-106 

Smart Antennas for OFDM-WLANs Based on a Spatial-Temporal Multi-Scenario Channel Model

R. Alihemmati, G. Dadashzadeh, A. A. Shishegar, and N. Hojjat

PP. 107-114 

An Overview of PAPR Reduction Techniques for Multicarrier Transmission and Propose of New Techniques for PAPR Reduction

A. Zolghadrasli and M. H. Ghamat

PP. 115-120 

New Low Destructive and High Capacity Image Steganographic Method

B. Ramazannia and H. Miar Naimi

PP. 121-126 

Fingerprint Compression Using Non-linear Approximation of Multiwavelet Coefficients

S. Esakkirajan, T. Veerakumar, V. Senthil Murugan, and P. Navaneethan

PP. 127-133 

Wideband Fractal Butterfly Patch Antenna

M. Jamshidifar, J. Nourinia, Ch. Ghobadi, and F. Arazm

PP. 134-136 

Ferrite Tuned Dual-Mode Dielectric Resonator Filters

M. Naser-Moghadasi

PP. 137-139 

Performance Evaluation and Comparison of Conventional and FACTS Controllers in Mitigating Chaos Driven Instabilities

D. Padma Subramanian and R. P. Kumudini Devi

PP. 140-146 

Decoupled Control of Salient Pole Synchronous Motor Drive

M. Rahimi, H. Mokhtari, and Gh. Zafarabadi

PP. 147-152 

Measurement of Harmonics Using Wavelet Packets

S. Suja and J. Jerome

PP. 153-158 

Parameter Identification of a DC Motor via Moments Method

M. Hadef, A. Bourouina, and M. R. Mekideche

PP. 159-163 


Abstracts:


Impact of TCPAR on Cluster-based Congestion Management Using Improved Performance Index

 

A. Kumar*, S. C. Srivastava*, and S. N. Singh*

*  Department of Electrical Engineering, Indian Institute of Technology Kanpur, India

 

Abstract: In this paper, transmission congestion distribution factors (TCDFs) based on sensitivity of line real power flow and full AC load flow Jacobian sensitivity have been proposed to identify the congestion clusters. The system operator (SO) can identify the generators from the most sensitive congestion clusters to reschedule their generation optimally to manage transmission congestion efficiently. The role of thyristor controlled phase angle regulator (TCPAR) has been investigated for reducing the transmission congestion cost after locating it optimally in the system based on improved performance index. The study has been carried out on 39-bus New England system and 75-bus practical Indian system.



A Comparison of Various Hybrid Elliptical Antenna Arrays

 

R. A. Sadeghzadeh*, A. A. Lotfi Neyestanak**, M. Naser-Moghadasi***, and M. Ghiamy****

* Khajeh-Nasir University of Technology, Electrical Engineering Dept., Tehran, Iran

**  Iranian Research Institute for Electrical Engineering, Tehran, Iran

*** Member of Central Commission for Scientific, Literacy & Art Societies Islamic Azad University Science and Research Branch, Tehran, Iran

**** Islamic Azad University, Science and Research Branch, Tehran, Iran

 

Abstract: In this paper, novel types of antenna arrays constructed from combination of linear and elliptical antenna arrays, are presented. These types are called EA, CEA, ECA, ECCA, HA, CHA, HCA, HCCA, HCCA, ECOA, ECCOA, HCOA and HCCOA where only the array factors are considered. The effect of the element factor can be considered separately and combined to the array factor. The expressions for all array factors have been obtained. HA is treated as consisting of two concentric N-element elliptical arrays of different semi-major and semi-minor axes and ECOA is treated as EA's that are placed one above another, so that the semi-major and semi-minor axes of each EA decrease linearly. The directivities and side lobe levels of them are simulated and compared for various ellipse eccentricity, element spacing and number of elements. Simulations show that CHA has the best directivity and ECOA has the lowest SLL.



Smart antennas for OFDM-WLANs based on a Spatial-Temporal Multi-scenario Channel Model

 

R. Alihemmati*, G. Dadashzadeh*, A. A. Shishegar**, and N. Hojjat***

* Iran Telecommunication Research Center, Tehran, Iran

** Electrical Engineering Department, Sharif University of Technology, Tehran, Iran

***Electrical Engineering Department, University of Tehran, Iran

 

Abstract: The combination of smart antenna techniques and OFDM could be considered as a promising solution for improving the performance and enhancing the data rates of next generation wireless communication systems operating in frequency selective fading environments. There are different design parameters which could affect the application of adaptive arrays in OFDM-based systems. Various beam-forming methods in frequency or time domain, different array architectures and various number of array elements are important factors which are able to change the performance and complexity of the system. These parameters may show different effects in different channel conditions. In this paper we implemented a new wideband spatio-temporal channel model for IEEE 802.11a WLAN with a variety of possible channel scenarios and array architectures. For each scenario, we have investigated different smart antennas configurations and implementation methods in order to find the optimum adaptive array for each scenario.

  


An overview of PAPR Reduction Techniques for Multicarrier Transmission and Propose of New Techniques for PAPR Reduction

 

A. Zolghadrasli* and M. H. Ghamat*

* EE Dept. School of Eng. Shiraz University, Shiraz, Iran

  

Abstract:This article describes some of the important PAPR reduction techniques for multicarrier transmission system including amplitude clipping , filtering, coding, partial transmit sequence, selected mapping, interleaving, tone reservation, tone injection and active constellation extension. The authors then present two new techniques based on selective Mapping (SLM) and selective scrambling combined with Hadamard matrix to reduce peak-to-average power ratio (PAPR) in OFDM systems.

 



New Low Destructive and High Capacity Image Steganographic Method

 

B. Ramazannia* and H. Miar Naimi*

*  Electrical Engineering Faculty, University of Mazandaran, Iran

 

Abstract: Using advantages of previous algorithms along with two novel points, a new low destructive image steganographic method is proposed. The proposed method is supported by mathematical theorems. The host image is segmented into blocks of pairs of successive pixels. The secret data are hidden in these two-pixel blocks. The secret data is considered as a stream of bits and is run length coded. Here 0 and 1s are runvalues and the number of runvalues in each run is runcount. There are two novel points in this paper, as the first the RLC coded secret bit stream is rearranged so that there is no need to embed runvalues, and only runcounts are embedded. This point reduces the volume of embedded data considerably. As the second point, the runcounts greater than a predefined value are embedded in more than one block, limiting local destruction. The embedding process incorporates the modular arithmetic. Using different experiments under various conditions, the proposed algorithm was compared to the last published method. In all experiments, for the same size of embedded data the proposed algorithm has 4db to 12db lower destruction than the last algorithm.



Fingerprint Compression Using Non-linear Approximation of Multiwavelet Coefficients

 

S. Esakkirajan*, T. Veerakumar**, V. Senthil Murugan***, and P. Navaneethan****

* Department of Instrumentation and Control Engineering, PSG College of Technology, India

**Department of Electronics and Communication Engineering, PSG College of Technology, Coimbatore-641004, India

***Mahindra and Mahindra, Automotive sector, Nasik, India

****Department of Electrical and Electronics Engineering, PSG College of Technology, Coimbatore, India

 

 

Abstract: This paper presents a new fingerprint coding technique using non-linear approximation of multiwavelet coefficients followed by multi-stage vector quantization. Fingerprints contain oscillatory patterns in the vertical, horizontal and diagonal direction. Wavelet transform often fails to accurately capture the oscillatory patterns in the fingerprints, especially at low bit rates. Due to implementation constraints scalar wavelets do not posses all the properties such as orthogonality, short support, linear phase symmetry, and a high order of approximation through vanishing moments simultaneously, which are very much essential for efficient image compression. New class of wavelets called ‘Multiwavelets’ which posses more than one scaling function overcomes this problem. The effective multiwavelet coefficients are quantized by multistage vector quantization which can achieve very low encoding and storage complexity in comparison to unstructured vector quantization.  Entropy coding of quantized coefficients is done using Huffman coding. The performance of the proposed scheme is compared with the results obtained from scalar wavelets. The performance of the proposed scheme is better than the existing wavelet based coding at low bit rate.

 



Wideband Fractal Butterfly Patch Antenna

 

M. Jamshidifar*, J. Nourinia*, Ch. Ghobadi*, and F. Arazm*

* Department of Electrical Engineering, Urmia University, Urmia, Iran

 

Abstract: In recent few years fractals have been employed in conjunction with antennas to develop new applications. In this work, a novel fractal geometry is introduced as a miniaturized microstrip patch antenna. Compare to a square patch antenna, the moment method simulations have shown an improvement of 68% size reduction. Furthermore, by applying of a new feeding method, refereed to here as the Sleeve Feeding, up to 27% impedance bandwidth is achieved as shown in the experiments.

 



Ferrite Tuned Dual-Mode Dielectric Resonator Filters

 

M. Naser-Moghadasi *

* Faculty of Engineering, Shahed University, Tehran, Iran

 

Abstract: This paper is devoted to the design and construction of a novel technique for ferrite tuning of dielectric loaded, dual-mode cavity filters. This is dealt with in two specific areas:

i) Improving the technique to realize a high – Q , low loss, dielectric-loaded, dual-mode cavity band-pass filter, using the hybrid HEM-sub-11delta mode,

ii) Developing techniques to obtain a wide range tuning mechanism, using ferrite materials. The designed dual-mode filters offer unloaded Q-sub-u of more than 10,000 with an insertion loss less than 1 dB. It is shown that ferrite tuning is possible either at below resonance or at the above resonance state, depending upon the strength of the applied DC magnetic field. Experimental results showed that due to its lower saturation magnetization YIG offers a wider tuning range compared with Nickel ferrite.

 



Performance Evaluation and Comparison of Conventional and FACTS Controllers in Mitigating Chaos Driven Instabilities

 

D. Padma Subramanian* and R. P. Kumudini Devi*

* Electrical Engineering Department, Power Systems Division, College of Engineering, Guindy, Anna University, Tamilnadu, India

 

Abstract:This paper concentrates on performance evaluation and comparison of conventional controllers such as Mechanically Switched Capacitor (MSC), Load Tap Changer (LTC), Power System Stabilizer (PSS), and FACTS controllers such as Static Var Compensator (SVC), Thyristor Controlled Series Capacitor Power Oscillation Damper (TCSC POD) controller and Unified Power Flow Controller (UPFC) in mitigating chaos driven instabilities such as voltage and angle instabilities. The chaos is triggered by the non-linearities associated with high gain fast excitation system of automatic voltage regulator (AVR) and shunt capacitors. The instability problem is explored by invoking bifurcation theory. Bifurcation diagrams of steady state as well as periodic solutions are plotted. From the bifurcation diagrams, the existence of various bifurcation points such as, Hopf Bifurcation (HBF), Saddle Node Bifurcation (SNB) and Period Doubling Bifurcation (PDB) are identified. With the use of tools of nonlinear dynamics, voltage collapse points, chaotic solutions due to period doublings and chaos divergence points are unearthed. Comprehensive comparisons of the effectiveness of the controllers are presented from the point of view of delaying HBF, SNB and increasing the loadability limit.

 



Decoupled Control of Salient Pole Synchronous Motor Drive

 

S. Kumar* and B.Umamaheswari*

* Electrical and Electronics Engineering, Anna University, Chennai 600 025, India

 

Abstract: This paper describes the performance of simultaneous control of torque and contactless power extraction in Salient Pole Synchronous Motor (SPSM) using Direct Torque Control (DTC) method. The field windings are kept unexcited and the reluctance torque due to the saliency is utilized. When the stator current is modulated with higher frequency component would establish induced voltages in the rotor, which could be used for supplying power to rotating load. This technique eliminates slip rings in the rotating assembly.Normally, the DTC is used to maintain constant torque. In this paper, the DTC technique can be extended to accommodate the rotating secondary transformer action also. The control scheme is demonstrated through simulation and tests on SPSM. The simulation results illustrates the various modes of operation is possible to produce reluctance torque, delivering rotor power through excitation winding and combination of bothtem.

 



Measurement of Harmonics Using Wavelet Packets

 

S. Suja* and J. Jerome*

*Electrical and Electronics Engineering Department, Coimbatore Institute of Technology, Coimbatore 641014, Tamil Nadu, India

 

Abstract: This paper presents a new method based on the wavelet packet transform for the analysis of harmonics in power systems. The algorithm can simultaneously measure the rms value of current, voltage and power using wavelet packets transform. The advantage of the wavelet packets transform is that it can decompose a power signal into uniform frequency bands. This decomposition into uniform frequency bands helps for the identification of harmonic components and measure of harmonic parameters. The algorithm is validated using simulated waveforms from the full wave inverter bridge circuit.

 



Parameter Identification of a DC Motor via Moments Method

 

M. Hadef*, A. Bourouina*, and M. R. Mekideche*

* LAMEL Laboratory, University of Jijel, Algeria

 

Abstract:The identification process consists of estimating the unknown parameters of system dynamics. Consequently, determination of the assumed system structure is of great importance in the process of system identification. Time moments have been introduced in automatic control because of the analogy between the impulse response of a linear system and a probability function. This basic idea has generated applications in identification, model order reduction and controller design. In this paper, a newly developed identification algorithm, called moments method, is introduced and applied to the parameter identification of a dc motor. The simulation and experimental results are presented and compared.

 

ISSN: 1682-0053
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