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
Sona,Kundukulam O; Manju,Paulson; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, December 5, 2001)
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Abstract:
Dual frequency operation is achieved from a compact
microstrip antenna by loading a pair of narrow slots close to its radiating
edges. The two frequencies have parallel polarization planes and similar
radiation characteristics. The ratio between the two operating frequencies
can be tuned in the range (1.14-1. 24), which is much smaller than that
of similar designs. The above excellent radiation characteristics are
achieved along with an area reduction of - 75% compared to the
standard rectangular patch
Jitha, B; Nimisha, C S; Aanandan,C K; Mohanan, P; Vasudevan, K(John Wiley & Sons, July , 2006)
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Abstract:
The use of a split-ring resonator (SRR)-loaded waveguide for the design of a band-rejection filter with adjustable bandwidth is reported. The width of the stopband can be adjusted by suitably positioning the SRR array in the waveguide. The rejection band can be made very narrow by placing the array at the electric-field minimum. The stopband attenuation depends on the number of unit cells in the array.
Jianlang,Li; Liren,Liu; Yingchun,Guo; Huaisheng,Wang; Changhe,Zhou(Microwave and Optical Technology Letters, December 20, 1999)
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Abstract:
The transient interaction between a refraction index grating
and light beams during simultaneous writing and thermal fixing of
a photorefractive hologram is investigated. With a diffusion- and
photovoltaic-dominated carrier transport mechanism and carrier thermal
activation (temperature dependent) considered in Fe:LiNbO3 crystal, from
the standpoint of field-material coupling, the theoretical thermal fixing
time and the space-charge field buildup, spatial distribution, and temperature
dependence are given numerically by combining the band transport
model with mobile ions with the coupled-wave equation
Design and development of a new feed -horn antenna
with low sidelobe levels is reported . The E-walls of this
antenna are fabricated with low -loss dielectric substrate ,
periodicallyloaded with thin conducting strips . The antenna
is found to be simulating the radiation characteristics of metallic
Corrugated horns . This can be an ideal substitute for metallic
Corrugated horns with added advantages like light -weight and low
production cost
K G Nair; Mohanan, P; Stephen, Rodrigues(Department of Electronics, 1991)
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Abstract:
Design and development of a new feed -horn antenna
with low sidelobe levels is reported . The E-walls of this
antenna are fabricated with low -loss dielectric substrate , periodically
loaded with thin conducting strips . The antenna is found
to be simulating the radiation characteristics of metallic corrugated
horns . This can be an ideal substitute for metallic corrugated
horns with added advantages like light -weight and low
production cost.
Mohanan, P; K G Nair; Stephen, Rodrigues(Department of Electronics, November , 1991)
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Abstract:
Design and development of a new feed -horn antenna
with low sidelobe levels is reported . The E-walls of this
antenna are fabricated with low -loss dielectric substrate , periodically
loaded with thin conducting strips . The antenna is found
to be simulating the radiation characteristics of metallic corrugated
horns . This can be an ideal substitute for metallic corrugated
horns with added advantages like light -weight and low
production cost.
Joseph, V P; Biju Kumar, S; Mathew, K T(John Wiley & Sons, April 5, 2001)
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Abstract:
The radiation characteristics of a new type of hollow dielectric H-plane sectoral horn antenna are presented. Metallic strips of optimum length are loaded on the H-walls of the sectoral horns. The effects of strip loading for producing square patterns in the H plane are discussed.
The (Ba1-x Srx) (Nd1/2, Nb1/2) O3 ceramics have been prepared by the conventional
ceramic route for different values of x. Addition of a small amount of
CeO2(1 wt%) as a sintering aid increased the density of the samples. The structure
and microstructure of the sintered samples are studied by X-ray diffraction
and SEM methods. The dielectric properties of the samples are measured in the
microwave frequency region as a function of composition. The dielectric constant
decreases as x increases. The coefficient of thermal variation of resonant
frequency decreases as the Sr content increases and goes to the negative side.
The dielectric properties of (Ba1-x Srx) (Nd1/2, Nb1/2) O3 are in the range suitable
for application as dielectric resonators in microwave circuits