Aanandan,C K; K G Nair; Mohanan, P; Jacob,George(Department of Electronics, November , 1998)
[+]
[-]
Abstract:
A new compact microstrip antenna element is analyzed.
The analysis can accurately predict the resonant frequency,
input impedance, and radiation patterns. The predicted results
are compared with experimental results and excellent agreement
is observed . These antenna elements are more suitable in applications
where limited antenna real estate is available
Jacob,George; Aanandan,C K; Mohanan, P; K G Nair(IEEE Journals/ Transactions (USA), 1998)
[+]
[-]
Abstract:
A new compact micro strip antenna element is analyzed.
The analysis can accurately predict the resonant frequency,
input impedance, and radiation patterns. The predicted results
are compared with experimental results and excellent agreement
is observed . These antenna elements are more suitable in applications
where limited antenna real estate is available
Mohanan, P; K G Nair; Aanandan,C K; Supriyo,Dey(Department of Electronics, February 3, 1994)
[+]
[-]
Abstract:
The closed form expression for the radiated power of a half-wave
microstrip patch is modified to calculate the impedance
bandwidth of a printed dipole. Analyses of cavity backed flared
and end-loaded printed dipoles are presented
Huo,Y; Taylor,G W(Microwave and Optical Technology Letters, May 20, 2003)
[+]
[-]
Abstract:
The operation of a previously proposed terahertz (THZ)
detector is formulated in detail. The detector is based on the hot-electron
effect of the 2D electron gas (2DEG) in the quantum well (QW) of
a GaAs/AIGaAs heterostructure. The interaction between the THz radiation
and the 2DEG, the current enhancement due to hot -electron effect, and
the noise performance of the detector are analyzed
Sona,Kundukulam O; Manju,Paulson; Aanandan,C K; Mohanan, P(Microwave Engineering Group,Department of Electronics, April 20, 2002)
[+]
[-]
Abstract:
Design equations are presented for calculating the resonance frequencies for a
compact dual frequency arrow-shaped microstrip antenna. This provides a fast and simple
way to predict the resonant frequencies of the antenna. The antenna is also analyzed using the
IE3D simulation package. The theoretical predictions are found to be very close to the
IE3D results and thus establish the validity of the design formulae
Choudhury, P K; Roger, Lessard S(Microwave and Optical Technology Letters, January 20, 2002)
[+]
[-]
Abstract:
An attempt is made to determine the relative power
distribution in a step-index parabolic cylindrical waveguide (PCW) with
high deformation across the direction of propagation. The guide is
assumed to be made of silica. The scalar field approximation is employed
for the analysis under which a vanishing refractive-index (RI) difference
in the waveguide materials is considered. Further, no approximation for
folds- is used in the analytical treatment. Due to the geometry of such
waceguides, PCWs lose the well-defined modal discreteness, and a kind
of mode bunching is observed instead, which becomes much more
prominent in PCWs with high bends. However, with the increase in
cross-sectional size, the mode-bunching tendency is slightly reduced. The
general expressions for power in the guiding and nonguiding sections are
obtained, and the fractional power patterns in all of the sections are
presented for PCWs of various cross-sectional dimensions. It is observed
that the confinement of power in the core section is increased for PCWs
of larger cross-sectional size. Moreover, a fairly uniform distribution of
power is seen over the modes having intermediate values of propagation
constants
Tennant,A; Dawoud,M M; Anderson,A P(Department of Electronics, April 27, 1994)
[+]
[-]
Abstract:
A genetic algorithm has been used for null steering in phased and
adaptive arrays . It has been shown that it is possible to steer the
array null s precisely to the required interference directions and to
achieve any prescribed null depths . A comparison with the results
obtained from the analytic solution shows the advantages of using
the genetic algorithm for null steering in linear array patterns
The characterization and grading of glioma tumors, via image derived features, for diagnosis, prognosis, and treatment response has been an active research area in medical image computing. This paper presents a novel method for automatic detection and classification of glioma from conventional T2 weighted MR images. Automatic detection of the tumor was established using newly developed method called Adaptive Gray level Algebraic set Segmentation Algorithm (AGASA).Statistical Features were extracted from the detected tumor texture using first order statistics and gray level co-occurrence matrix (GLCM) based second order statistical methods. Statistical significance of the features was determined by t-test and its corresponding p-value. A decision system was developed for the grade detection of glioma using these selected features and its p-value. The detection performance of the decision system was validated using the receiver operating characteristic (ROC) curve. The diagnosis and grading of glioma using this non-invasive method can contribute promising results in medical image computing
Description:
International Journal of Emerging Technologies in Computational and Applied Sciences, 7(1), December 2013-
February, 2014, pp. 08-14
Efficient optic disc segmentation is an important task in automated retinal screening. For the same reason optic disc detection is fundamental for medical references and is important for the retinal image analysis application. The most difficult problem of optic disc extraction is to locate the region of interest. Moreover it is a time consuming task. This paper tries to overcome this barrier by presenting an automated method for optic disc boundary extraction using Fuzzy C Means combined with thresholding. The discs determined by the new method agree relatively well with those determined by the experts. The present method has been validated on a data set of 110 colour fundus images from DRION database, and has obtained promising results. The performance of the system is evaluated using the difference in horizontal and vertical diameters of the obtained disc boundary and that of the ground truth obtained from two expert ophthalmologists. For the 25 test images selected from the 110 colour fundus images, the Pearson correlation of the ground truth diameters with the detected diameters by the new method are 0.946 and 0.958 and, 0.94 and 0.974 respectively. From the scatter plot, it is shown that the ground truth and detected diameters have a high positive correlation. This computerized analysis of optic disc is very useful for the diagnosis of retinal diseases
Description:
(IJACSA) International Journal of Advanced Computer Science and Applications,
Vol. 5, No. 7, 2014
This paper describes a novel framework for automatic
segmentation of primary tumors and its boundary from brain
MRIs using morphological filtering techniques. This method uses
T2 weighted and T1 FLAIR images. This approach is very
simple, more accurate and less time consuming than existing
methods. This method is tested by fifty patients of different
tumor types, shapes, image intensities, sizes and produced better
results. The results were validated with ground truth images by
the radiologist. Segmentation of the tumor and boundary
detection is important because it can be used for surgical
planning, treatment planning, textural analysis, 3-Dimensional
modeling and volumetric analysis
Description:
2012 5th International Conference on BioMedical Engineering and Informatics (BMEI 2012)
Mohanan, P; Aanandan,C K; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
[+]
[-]
Abstract:
A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed.
This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also
improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find
practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio
astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna
characteristics
Mohanan, P; Pravinkumar,P A; K G Nair(Indian Journal of Radio & Space Physics, 1982)
[+]
[-]
Abstract:
A simple technique for obtaining identical E- and H-plane patterns from E-plane sectoral feed horn is presented. Halfpower
beam width and gain of the antenna are also improved considerably. Experimental results for a number of horns with
flanges of various parameters are also presented. This system may find practical application in radar and space communication
systems
Ajaikumar,V; Jose,K A; Aanandan,C K; Mohanan, P; K G Nair(Microwave and Optical Technology Letters, October , 1992)
[+]
[-]
Abstract:
Reduction of radar cross -section of dihedral corner reflectors using
simulated corrugated surface (.SCS) is reported. This technique is
found lo be more effective in the reduction of RCS or corner reflectors
for normal incidence . A typical reduction of 40-50 dB is
achieved using this method
Mohanan, P; Aanandan,C K; K G Nair(Department of Electronics, October , 1992)
[+]
[-]
Abstract:
Reduction of radar cross -section of dihedral corner reflectors using
simulated corrugated surface (SCS) is reported. The technique is
found to be more effective in the reduction of RCS or corner reflectors
for normal incidence . A typical reduction of 40-50 dB is
achieved using this method.
A new microwave dielectric resonator Ba(Tb1/2Nb1/2)03 has been prepared and characterized in the microwave frequency region. 1 wt% CeO2 is used as additive to reduce the sintering temperature. The sintered samples were characterized by XRD, SEM and Raman spectroscopic methods. Microwave DR properties such as er, Q factor and temperature-coefficient of resonant frequency (Ti) have been measured using a HP 8510 B Network Analyzer. Cylindrical DRs of Ba(Tb1/2Nbi/2)03 showed high Er (~ 37), high Q (~3,200) and low Tf (~10 ppm /°C) at 4 GHz and hence are useful for practical applications
Mathew, K T; Robin, Augustine; Ullas, Kalappura G(Wiley InterScience, November , 2008)
[+]
[-]
Abstract:
Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) bioceramic and
chitosan (poly [( -1-4) D-glucosamine]) biopolymer show good biocompatibility
in vivo. They have biological origin and show excellent interactions
with microwave. Microwave study of HAp made using different
drying techniques and their composites with chitosan in the ISM band is
presented. Pastes are made using HAp and chitosan with different ratios
of mixing. The dielectric properties of this composites match with that of
human fat, collagen tissues. Some of the compositions exhibit dielectric
property close to that of natural bone. This makes them more
biocompatible and better substitutes for natural bone. Thus composite
bioceramics can be considered as phantom model constituents for
imaging purposes. Their dielectric properties prove that they are
biocompatible.
Raveendranath, U; Bijukumar, S; Mathew, K T(IEEE, December , 2000)
[+]
[-]
Abstract:
A novel cavity perturbation technique using coaxial cavity resonators for the measurement of complex permittivity of liquids is presented. The method employs two types of resonators (Resonator I and Resonator II). Resonator I operates in the frequency range 600 MHz-7 GHz and resonator II operates in the frequency range 4 GHz-14 GHz. The introduction of the capillary tube filled with the sample liquid into the coaxial resonator causes shifts in the resonance frequency and loaded Q-factor of the resonator. The shifts in the resonance frequency and loaded Q-factor are used to determine the real and imaginary parts of the complex permittivity of the sample liquid, respectively. Using this technique, the dielectric parameters of water and nitrobenzene are measured. The results are compared with those obtained using other standard methods. The sources of errors are analyzed.