Showing papers by "Anup Kumar Bhattacharjee published in 2011"

Application of evolutionary optimization techniques for finding the optimal set of concentric circular antenna array

Abstract: In this paper the maximum sidelobe level (SLL) reductions, optimal beam patterns and optimal beam widths of various designs of three-ring planar concentric circular antenna arrays (PCCAA) are examined using three different classes of evolutionary optimization techniques to finally determine the global optimal three-ring PCCAA design and then establish some sort of ranking among the techniques. Apart from physical construction of a PCCAA, one may broadly classify its design into two major categories: uniformly excited arrays and non-uniformly excited arrays. The present paper assumes non-uniform excitations and uniform spacing of excitation elements in each three-ring PCCAA design and a design goal of maximizing SLL reduction associated with optimal beam patterns and beam widths. The design problem is modeled as an optimization problem for each PCCAA design and solved using different evolutionary optimization techniques to determine an optimum set of normalized excitation weights for PCCAA elements, which, when incorporated, results in a radiation pattern with optimal (maximum) SLL reduction. Among the various PCCAA designs, one which yields the global minimum SLL with global minimum first null beamwidth is the global optimal design. In this work the three-ring PCCAA containing (N"1=4, N"2=6, N"3=8) elements proves to be such global optimal design. The optimization techniques employed are real coded GA (RGA), canonical PSO (CPSO), craziness based PSO (CRPSO), evolutionary programming (BEP), hybrid evolutionary programming (HEP). While ranking the techniques after 30 total runs for each design, HEP, CRPSO, RGA, CPSO, BGA hold the first five ranks in order of optimization capability. HEP yields global minimum SLL (-32.86dB) and global minimum BWFN (77.0^o) for the optimal design. BEP often changes the rank from second to fifth depending on the design set. Further, when compared to a uniformly excited PCCAA having equal number of elements and same radii a reduction of major lobe beamwidth is also observed in the optimal non-uniformly excited case.

Wide null control of symmetric linear antenna array using novel particle swarm optimization

Abstract: In this article, the method of nullifying the radiation pattern of a symmetric linear antenna array in a particular direction is propounded using an evolutionary swarm intelligence technique, Novel particle swarm optimization (NPSO). Particle swarm optimization with constriction factor approach (PSOCFA) is also adopted to compare the NPSO based results. Single or multiple wide nulls are achieved by optimum perturbations of elements current amplitude weights to have symmetric nulls about the main beam. Different numerical examples are presented to illustrate the capability of NPSO for pattern synthesis with a prescribed wide nulls locations and depths. Further, the peak Sidelobe Levels are also reduces when compared to a uniformly excited array having equal number of elements. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. © 2011 Wiley Periodicals, Inc.

A Discrete Wavelet Transform based Cryptographic algorithm

Abstract: This paper presents a new and efficient algorithm for cryptographic purpose that considers the representation of the cipher text by using the Discrete Wavelet Transform to find the wavelet decomposition vector containing the approximation and the detail coefficients. The decryption is done by extracting the encrypted data from the wavelet decomposition vector using the inverse Discrete Wavelet Transform algorithm. The encrypted message consists of just the wavelet decomposition vector. The key consists of the code number of the wavelet used and the bookkeeping vector.

MRI segmentation using Entropy maximization and Hybrid Particle Swarm Optimization with Wavelet Mutation

Abstract: A Hybrid Particle Swarm Optimization algorithm that incorporates a Wavelet theory based mutation operation is used for segmentation of Magnetic Resonance Images. We use Entropy maximization using Hybrid Particle Swarm algorithm with Wavelet based mutation operation to get the region of interest of the Magnetic Resonance Image. It applies the Multi-resolution Wavelet theory to enhance the Particle Swarm Optimization Algorithm in exploring the solution space more effectively for a better solution. Tests on various MRI images with lesions show that lesions are successfully extracted.

Linear Antenna Array Synthesis Using Improved Particle Swarm Optimization

Abstract: In this paper the synthesis of linear array geometry with minimum side lobe level using a new class of Particle Swarm Optimization technique namely Improved Particle Swarm Optimization (IPSO) is described. The IPSO algorithm is a newly proposed, high-performance evolutionary algorithm capable of solving general N-dimensional, linear and nonlinear optimization problems. Compared to other evolutionary methods such as genetic algorithms and simulated annealing, the IPSO algorithm is much easier to understand and implement and requires the least of mathematical pre-processing. The array geometry synthesis is first formulated as an optimization problem with the goal of side lobe level (SLL) suppression, and then solved by the IPSO algorithm for the optimum element locations and current excitations. Five design examples are presented that illustrate the use of the IPSO algorithm, and the optimization goal in each example is easily achieved.

Quantum breathers in Klein-Gordon lattice: Non-periodic boundary condition approach

Abstract: The presence of classical breathers and two-phonon bound state (TPBS) or quantum breather (QB) state through detailed quantum calculations have already been shown in technologically important ferroelectric materials, such as lithium niobate with antisite niobium charge defects concerning pinning transition, its control, and application. The latter was done in a periodic boundary condition with Bloch function in terms of significant variations of TPBS parameters against impurity, which is related to nonlinearity. In further extension of this work, in a non-periodic boundary condition and number-conserving approach, apart from various techniques available, only the temporal evolution of the number of quanta (i.e., phonons) in more sites is detailed in this present investigation for a generalized Klein-Gordon system with applications in ferroelectrics, metamaterials, and DNA. The critical time of redistribution of quanta that is proportional to the QB’s lifetime in these materials shows different types of be...

A cross-layer based multipath routing protocol for IEEE 802.11E WLAN

Abstract: In spite of many enhancement mechanisms are introduced to achieve QoS support in IEEE 802.11e WLAN based on Hybrid Coordination Function Controlled Channel Access (HCCA), performance evaluation results in multi-hop networks show that HCCA still suffers from significant throughput degradation and high delay at high load conditions. In this context, the route quality plays a vital role in the success of application delivery and QoS support. This paper proposes a design of a cross-layer based multipath routing protocol for IEEE 802.11e WLAN. In this proposed approach, initially multiple disjoint paths are determined. Then a total cost metric is estimated based on the Traffic Contention Time, Average Transmission Delay and Signal Fading Value. From the multiple disjoint paths, the path with minimum total cost is selected as best path and the data is transmitted through this path. The simulation results show that the proposed protocol achieves better delivery ratio and throughput with reduced delay.

A dual wideband Sierpinski carpet fractal-shaped planar monopole antenna with CPW feed

Abstract: A dual wideband design of Sierpinski carpet fractal-shaped planar monopole antenna with a coplanar waveguide (CPW) feed is proposed in this letter. Wide impedance bandwidth of 22% at lower resonance from 4.88 to 6.08 GHz and 41.7% at higher one, which ranges from 9.5 to 14.5 GHz, is obtained. Measured realized antenna gain is around 5 dBi at the lower band centered around 5.5 GHz and are around 4.5 dBi at the higher band. A fabricated prototype is developed with good agreement between simulation and measurement.

Swarm Intelligence Based Synthesis of Concentric Circular Antenna Array for Broadside Radiation

Abstract: In many applications it is desirable to have the maximum radiation of an array directed normal to the axis of the array. In this paper, the broadside radiation patterns of three-ring Concentric Circular Antenna Arrays (CCAA) with central element feeding are reported. For each optimal synthesis, optimal current excitation weights and optimal radii of the rings are determined having the objective of maximum Side lobe Level (SLL) reduction. The optimization technique adopted is Craziness based Particle Swarm Optimization (CRPSO). The extensive computational results show that the particular CCAA containing 4, 6 and 8 number of elements in three successive rings along with central element feeding yields grand minimum SLL (-52.53 dB).

An Entropy Maximization based technique for Progressive Transmission of MRI Images

Abstract: We have devised a way of segmentation and progressive transmission of MRI images. Entropy maximization using Particle Swarm Algorithm (PSO) is used to get the Region of Interest (ROI). The ROI is de-noised using Multi-Wavelet Analysis. Soft Thresholding together with Stationary Wavelet is used for de-noising purpose. Varying percentages of Discrete Cosine Transform Coefficients are used for the purpose of progressive transmission. K-Means clustering is used for analysis of the MRI.

Effect of Modes of Rolling on Evolution of Texture and Yield Locus Anisotropy in a Multifunctional Ti-31Ta-12Nb-2V-8Zr-0.22O Alloy

Abstract: Present work describes the evolution of texture during different modes of deformation by cold rolling of a Gum metal or multifunctional β titanium alloy. The starting and cold rolled materials exhibit the presence of β and β with small amount of stress induced martensitic (α˝) phases, respectively. The development of texture has been explained in terms of α and γ fibres. The bulk hardness appears to be independent of modes of deformation by cold rolling. The yield surfaces of as received and solution treated samples exhibit marked anisotropy which persists during different modes of deformation by rolling.

Performance of Linear Arrays with Travelling Wave Current Distribution

Abstract: Antenna arrays are generally formed by assembly of radiating elements kept in a particular geometrical fashion. If the elements are kept in linear fashion then array is known as linear array and if same are kept in circular fashion then array known as circular array and so on. Most of the works on linear array are based on assumption that excitation current applied to array element is constant. In the present work we evaluate array factor of linear array with traveling wave current excitation and then we compare performance of linear array with both type of excitation.