Chandran,A R; Gopikrishna, M; Aanandan,C K; Mohanan, P; Vasudevan, K(IEEE, September 28, 2006)
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Abstract:
Effective use of fractal-based metallo-dielectric structures for enhancing the radar cross-section (RCS) of dihedral corner reflectors is reported. RCS enhancement of about 30 dBsm is obtained for corner reflectors with corner angles other than 90deg. This may find application in remote sensing and synthetic aperture radar.
Gijo,Augustin; Shynu, S V; Mohanan, P; Aanandan,C K; Vasudevan, K(John Wiley & Sons, November , 2006)
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Abstract:
A novel fixed frequency beam scanning microstrip leaky wave antenna is reported. The beam scanning at fixed frequency is achieved by reactive loading. Simulation and measured results shows frequency scanability of 80° as well as fixed frequency beam steering of 68° over the −10 dB impedance band of 4.56–5.06 GHz.
James, Kurian; Saseendran Pillai, P R(December 8, 2008)
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Abstract:
This paper introduces a simple and efficient method
and its implementation in an FPGA for reducing the odometric
localization errors caused by over count readings of an
optical encoder based odometric system in a mobile robot
due to wheel-slippage and terrain irregularities. The detection
and correction is based on redundant encoder measurements.
The method suggested relies on the fact that the
wheel slippage or terrain irregularities cause more count
readings from the encoder than what corresponds to the
actual distance travelled by the vehicle. The standard quadrature
technique is used to obtain four counts in each encoder
period. In this work a three-wheeled mobile robot
vehicle with one driving-steering wheel and two-fixed rear
wheels in-axis, fitted with incremental optical encoders is
considered. The CORDIC algorithm has been used for the
computation of sine and cosine terms in the update equations.
The results presented demonstrate the effectiveness
of the technique
Description:
Journal of Automation, Mobile Robotics & Intelligent Systems VOLUME 3, No 3 2009
Shynu, S V; Gijo,Augustin; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, February 4, 2005)
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Abstract:
A novel reconfigurable, single feed, dual frequency, dualpolarized
operation of a hexagonal slot-loaded square mwrostrip antenna
is presented in this paper. A pin diode incorporated in the slot is
used to switch the two operating frequencies considerably, without significantly
affecting the radiation characteristics and gain. The proposed
antenna provides a size reduction up to 61% and 26% Jor the two resonating
frequencies, compared to standard rectangular patches. This design
also gives considerable bandwidth up to 3.3% and 4.27%, for the two
frequencies with a low operating frequency ratio
Mridula, S; Binu, Paul; Mohanan, P; Bijumon, P V; Sebastian,M T(URSI, October , 2005)
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Abstract:
Experimental investigations on Microstrip line excited Dielectric Resonator Antenna configurations suitable for Mobile Communication applications are reported. High permittivity (εrd = 48) resonator samples with different aspect ratios are employed for the study. Theoretical analysis performed using FDTD method is also presented.
Suma,M N; Sreedevi, Menon K; Bijumon, P V; Sebastian,M T; Mohanan, P(Microwave and Optical Technology Letters, April 20, 2005)
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Abstract:
In this paper, we present an effective excitation of a reelangular
dielectric resonator antennas (DRA) with a conductor-hacked
coplanar waveguide (CB-CPW). The radiation and resonance characteristics
are found to van,, depending on the orientation of the DR on
doe coplanar feed line. The effect of finite and infinite ground planes of
CB-CPIV on the radiation characteristics of the rectangular DRA is
studied. The orientation and position of the DR are optimized for maximum
gain and bandwidth. The optimized antenna ,geometry offers
--10.46 dBi gain and 7.5% bandwidth with low cross-polar radiation
characteristics
Paulson,M; Sona,Kundukulam O; Aanandan,C K; Mohanan, P(Department of Electronics, September , 2001)
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Abstract:
The arrow shaped microstrip antenna, which produces
dual frequency dual polarisation operation with considera-ble size reduction compared to conventional patches has been
reported [I]. These antennas provide greater area reduction and
improved gain compared to drum shaped patches [2]. Prediction
of the resonance frequency of drum shaped patches [3] and circular
patches for broadband operation [4] are available in the literature.
In this Letter, we propose empirical formulas for calculating
the resonance frequencies of the arrow shaped microstrip antenna.
These antennas can be employed for obtaining dual frequency
with the same polarisation, bandwidth enhancement, circular
polarisation etc. by varying its different parameters or by introducing
slots. The proposed design equations provide an easier and
simple way of predicting the resonant frequencies of these patches.
A simple technique for calculating the resonance frequencies of a
compact arrow-shaped microstrip antenna is presented and discussed . The accuracy of the method is validated by experimental results
Sona,Kundukulam O; Paulson,M; Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, October , 2002)
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Abstract:
A dual-port microstrip antenna with a crescent shaped
patch with excellent isolation betwecn the ports has been reportcd [I].
Since circular-sided geometries are inore compact than rectangular
oncs, thcy find morc applications in microstrip arrays. The crcscent
shaped antenna geometry [ I ] provides greater area rcductioii compared
to other circular sided patches for broadband operation [2]. In this
Lctter, formulac for calculating thc TM, I and TMZI mode resonant
frequencies of this microstrip antenna, obtained by modifying the
equations of a standard circular patch [3] are presentcd. Thcorctical
results are compared with experimental observations aid the validity
of the computation is established.
Chandran,A R; Gopikrishna, M; Aanandan,C K; Mohanan, P; Vasudevan, K(Progress In Electromagnetics Research, 2007)
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Abstract:
The scattering behaviour of fractal based metallodielectric structures loaded over metallic targets of different shapes such as flat plate, cylinder and dihedral corner reflector are investigated for both TE and TM polarizations of the incident wave. Out of the various fractal structures studied,square Sierpinski carpet structure is found to give backscattering reduction for an appreciable range of frequencies. The frequency of minimum backscattering depends on the geometry of the structure as well as on the thickness of the substrate. This structure when loaded over a dihedral corner reflector is showing an enhancement in RCS for corner angles other than 90◦.
Tessamma, Thomas; Ananda Resmi, S(Scientific Research Publishing, July 28, 2012)
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Abstract:
This work presents an efficient method for volume rendering of glioma tumors from segmented 2D MRI Datasets with user interactive control, by replacing manual segmentation required in the state of art methods. The most common primary brain tumors are gliomas, evolving from the cerebral supportive cells. For clinical follow-up, the evaluation of the pre- operative tumor volume is essential. Tumor portions were automatically segmented from 2D MR images using morphological filtering techniques. These seg- mented tumor slices were propagated and modeled with the software package. The 3D modeled tumor consists of gray level values of the original image with exact tumor boundary. Axial slices of FLAIR and T2 weighted images were used for extracting tumors. Volumetric assessment of tumor volume with manual segmentation of its outlines is a time-consuming proc- ess and is prone to error. These defects are overcome in this method. Authors verified the performance of our method on several sets of MRI scans. The 3D modeling was also done using segmented 2D slices with the help of a medical software package called 3D DOCTOR for verification purposes. The results were validated with the ground truth models by the Radi- ologist.
Description:
J. Biomedical Science and Engineering, 2012, 5, 378-383
Biju Kumar, S; Raveendranath, U; Mohanan, P; Mathew, K T; Hajian,M; Ligthart, L P(Microwave and Optical Technology Letters, July 20, 2000)
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Abstract:
A simple and efficient method for determining the complex
permittivity of dielectric materials from both reflected and transmitted signals is presented. It is also novel because the technique is implemented using two pyramidal horns without any focusing mechanisms. The dielectric constant of a noninteractive and distributive (NID) mixture of dielectrics is also determined
Vermeeren,G; Rogier,H; Olyslager,F; Zutter De,D(IEE Electronics letters,UK, September 13, 2001)
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Abstract:
A single-feed rectangular-ring microstrip antenna is proposed for
indoor communication under the Bluetooth protocol. The
dimensions of the antenna together with the location of the feed
point are optimized through field simulations in order to cover the
Bluetooth bandwidth and to avoid linear polarization. The
performance and the efficiency of the antenna are illustrated in a
real indoor environment
James, Kurian; Balakrishnan, K G; Nair, K G(IOP Publishing LTD, August 19, 1992)
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Abstract:
A simple and inexpensive power supply suitable for characteristics
studies of a klystron is described. The circuit is a modified form of the high voltage
adjustable power supply based on LM 317. This provides the necessary cavity and
repeller voltages over a wide range, with good regulation. The system is protected
aa- ainst short circuits and is ideallv suitable for laboratorv, ex.Deri ments with reflex
klystrons.
Hsieh,Gui-Bin; Chen,Ming-Huang; Wong,Kin-Lu Wong(IEE Electronics letters,UK, June 21, 2001)
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Abstract:
A novel technique for obtaining dual-hand circular polarization
(CP) radiation of a single-feed circular microstrip antenna in
proposed and demonstrated. By embedding two pain of arc shaped
slots of proper lengths close to the boundary of a circular
patch, and protruding one of the arc-shaped slots with a narrow
slit, the circular microstrip antenna can perform dual-hand CP
radiation using a single probe feed. Details of the antenna design
Binoy,G S; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave and Optical Technology Letters, June 20, 2000)
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Abstract:
A novel dual frequency dual-polarized square microstrip
patch antenna embedded with a slot is presented. The proposed
antenna offers tunability of the frequency ratio between the two
frequencies by adjusting the slot dimensions. This configuration
also provides a size reduction up to -51 and 35% for the two modes
as compared to a square micro strip patch antenna
In this paper, a new directionally adaptive, learning based, single image super resolution method using
multiple direction wavelet transform, called Directionlets is presented. This method uses directionlets to
effectively capture directional features and to extract edge information along different directions of a set of
available high resolution images .This information is used as the training set for super resolving a low
resolution input image and the Directionlet coefficients at finer scales of its high-resolution image are
learned locally from this training set and the inverse Directionlet transform recovers the super-resolved
high resolution image. The simulation results showed that the proposed approach outperforms standard
interpolation techniques like Cubic spline interpolation as well as standard Wavelet-based learning, both
visually and in terms of the mean squared error (mse) values. This method gives good result with aliased
images also.
Description:
International Journal of Artificial Intelligence & Applications (IJAIA), Vol.1, No.4, October 2010
Binoy,G S; Aanandan,C K; Mohanan, P; Vasudevan, K(Microwave Engineering Group,Department of Electronics, January 5, 2002)
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Abstract:
A novel dual frequency design of a square microstrip antenna coaxially
fed along the diagonal with a chip capacitor mounted at the bottom of
the stub is introduced. This design provides enhanced area reduction and
good cross-polarization levels. The antenna design can be used as a compact
antenna system where limited size is a major requirement. The details of the
antenna design and experimental results are presented
Mridula, S; Deepu, V; Sujith, R; Mohanan, P(Wiley Subscription Services, Inc., A Wiley Company, July 18, 2008)
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Abstract:
A slot line fed planar dipole antenna with a parasitic
strip for wide band applications is presented. The presented antenna
offers a 2:1 VSWR bandwidth from 1.66 to 2.71 GHz covering the DCS/
PCS/UMTS and IEEE 802.11b/g bands with a gain better than 6.5 dBi.
The uniplanar design, simple feeding, and high gain make it a versatile
antenna for wireless applications
Description:
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 3, March 2009