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Guha D.,University of Calcutta | Gupta B.,Girijananda Chowdhury Institute of Management and Technology | Kumar C.,Satellite Center | Antar Y.M.M.,Royal Military College of Canada
IEEE Transactions on Antennas and Propagation | Year: 2012

Hemispherical dielectric resonator antenna (HDRA) is reinvestigated by splitting it into four uniform quarters, which indeed generates a new DRA shape, proposed to call as "quarter-Hemispherical DRA" (q-HDRA). An innovative idea, gathered by the authors through their previous investigations, has been employed to investigate four-element q-HDRA resonating with dominant and first higher modes over a large impedance bandwidth (S 11 < - 10 dB) and producing improved monopole-like radiation pattern. The improvement has been described in terms of uniformity and symmetry in the radiation patterns obtained consistently over the entire operating bandwidth. No degradation or compromise in impedance bandwidth is observed. For this purpose, the new DRA unit (q-HDRA) has been characterized using simulated and measured data. Prototypes of single and multi-element q-HDRA have been measured and compared with some earlier versions. Unlike earlier one, consistently symmetric monopole-like radiation from a four element q-HDRA has been demonstrated. © 2006 IEEE. Source


Guha D.,University of Calcutta | Gupta B.,Girijananda Chowdhury Institute of Management and Technology | Antar Y.M.M.,Royal Military College of Canada
IEEE Transactions on Antennas and Propagation | Year: 2012

Two geometries of dielectric ring resonator (DRR) have been investigated as new variants for designing ultrawideband hybrid monopole-DRAs (dielectric resonator antennas) with improved features. They are simply hemispherical and conical in shape and have been implemented individually. Hybrid monopole-DRA is actually a combined configuration using a grounded monopole surrounded by a small DRR touching the same ground plane. Compared to an earlier version using cylindrical DRR of same dielectric material, the proposed ones promise for about 25% larger impedance bandwidth maintaining identical gain and radiation properties. As much as 126% impedance bandwidth with consistent monopole type radiation and 2-4 dBi peak gain has been demonstrated using a set of prototypes shaped from dielectric rod with ε r = 10. Physical insight in to the ultrawideband operation along with a comprehensive design guideline is presented. © 2006 IEEE. Source


Singha M.R.,Girijananda Chowdhury Institute of Management and Technology | Kalita B.,Assam Engineering College
Lecture Notes in Engineering and Computer Science | Year: 2013

Urban Traffic Network (UTN) can be represented as a directed graph say, G={V, E}, where V={v1,v2,v3⋯.,v m}, is a finite set of vertices and E={e1,e 2.e3,⋯,en}, is a finite set of edges. The vertices of UTN are the road junctions or terminals and the edges are road segments. The Mobile Phone Network (MPN) around the UTN can also be represented as a graph say G/={T, E} with vertices T={t1,t2, t3⋯.,tl} and edges E={e1,e2.e3, ⋯en}. The vertices t1,t2, t 3⋯.,tl are the points on the road segments nearest to Base Transceiver Station (BTS) Cell centre and the edges e1,e 2.e3,⋯en are the finite set of edges, same as the edges of UTN. In this paper, a method has been discussed to map a MPN onto a UTN. The mapping can be used for urban traffic management, such as counting the number of traffic users around a road junction. We have also stated and proved that "Any MPN graph can be constructed as an UTN graph". Further, we have used the application of the mapping in counting traffic users to find the traffic congestion levels. Source


Garai P.,National Institute of Science and Technology | Dutta C.B.,Girijananda Chowdhury Institute of Management and Technology
IET Seminar Digest | Year: 2014

In the recent days, the exponential growth in functionality of mobile devices leads the manufacturers to develop more and more sophisticated microprocessors and microcontrollers. The power requirements of the microprocessors are increasing day by day along with the processing speed and chip area. So, rather than traditional number systems, Residue Number System (RNS) is becoming attractive for their capabilities for performing addition and multiplication operation efficiently. In this paper, based on the formulation of the Chinese remainder theorem and RNS, a guideline for a Reconfigurable DSP Processor is proposed that can process some predefined functions. As RNS minimizes the carry propagation, the scheme can be implemented in Mobile and Wireless Computing and other fields where high speed computations are required with limited resources. Source


Goswami L.,Girijananda Chowdhury Institute of Management and Technology | Datta P.,Gauhati University
Journal of Nanoelectronics and Optoelectronics | Year: 2015

In the present study, we investigate the electron transport features of the PbS/PVA Quantum Dot (QD) devices under dark and light environment. The PbS/PVA QDs are synthesised via chemical route and are characterised by various techniques, viz. UV-Vis, PL, XRD, SEM, EDS, HRTEM and SAED which confirm nano formation and quantum confinement. Different devices are then fabricated with QDs of varying sizes by incorporating HTL or ETL/both HTL and ETL and the photo-sensitivity of the as-fabricated devices are studied under dark, and by exposing them to solar light, He-Ne laser and diode laser sources in the solar stimulator. I-V characteristics of the as-fabricated devices exhibit the Coulomb Blockade (CB) effect under light environment and Resonant Tunneling (RT) effect under dark environment. Dependance of degree of coupling between the electrodes and the QDs on environment may be the possible reason behind this finding. The complete device ITO/HTL/PbS QDs/ETL/Al is found to exhibit excitonic solar cell behavior rather than that of the conventional Schottky barrier/pn junction solar cell. Copyright © 2015 American Scientific Publishers All rights reserved. Source

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