Shyam S,Pattnaik; Dhruba C,Panda; Devi,S(Microwave and Optical Technology Letters, September 20, 2002)
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Abstract:
The mathematical formulation of empirically developed formulas Jirr the calculation of the resonant frequency of a thick-substrate
(h s 0.08151 A,,) microstrip antenna has been analyzed. With the
use qt' tunnel-based artificial neural networks (ANNs), the resonant frequency
of antennas with h satisfying the thick-substrate condition are
calculated and compared with the existing experimental results and also
with the simulation results obtained with the use of an IE3D software
package. The artificial neural network results are in very good agreement
with the experimental results
Riju, C Issac; Pramod, Gopinath; Geetha K, Varier; Nampoori, V P N; Vallabhan, C P G(American Institute of Physics, July 13, 1998)
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Abstract:
Laser-induced plasma generated from a silver target under partial vacuum conditions using the
fundamental output of nanosecond duration from a pulsed Nd:yttrium aluminum garnet laser is
studied using a Langmuir probe. The time of flight measurements show a clear twin peak
distribution in the temporal profile of electron emission. The first peak has almost the same duration
as the laser pulse while the second lasts for several microseconds. The prompt electrons are
energetic enough ('60 eV) to ionize the ambient gas molecules or atoms. The use of prompt
electron pulses as sources for electron impact excitation is demonstrated by taking nitrogen, carbon
dioxide, and argon as ambient gases.
Bindhu, C V; Harilal, S S; Achamma, Kurian; Nampoori, V P N; Vallabhan, C P G(World Scientific Publishing Company, 1998)
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Abstract:
Dual beam transient thermal lens studies were carried out in rhodamine 6G methanol solutions using 532 nm pulses from a frequency doubled Nd:YAG laser. Analysis of thermal lens signal shows the existence of different nonlinear processes like two photon absorption and three photon absorption phenomena along with one photon absorption. Concentration of the dye in the solution has been found to influence the occurrence of the different processes in a significant way.
Sreekumar, J; Nandakumaran, V M(World Scientific Publishing Company, 1990)
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Abstract:
Large amplitude local density fluctuations in a thin superfluid He film is considered. It is shown that these large amplitude fluctuations travel and behave like "quasi-solitons" under collision, even when the full nonlinearity arising from the Van der Waals potential is taken into account.
Bindu, G; Santhosh John, Abraham; Anil, Lonappan; Vinu, Thomas; Aanandan,C K; Mathew, K T(International Journal of Cancer Research, 2006)
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Abstract:
Despite its recognized value in detecting and characterizing breast disease, X-ray
mammography has important limitations that motivate the quest for alternatives to augment
the diagnostic tools that are currently available to the radiologist. The rationale for pursuing
electromagnetic methods are based on the significant dielectric contrast between normal
and cancerous breast tissues, when exposed to microwaves. The present study analyzes
two-dimensional microwave tomographic imaging on normal and malignant breast tissue
samples extracted by mastectomy, to assess the suitability of the technique for early
detection ofbreast cancer. The tissue samples are immersed in matching coupling medium
and are illuminated by 3 GHz signal. 2-D tomographic images ofthe breast tissue samples
are reconstructed from the collected scattered data using distorted Born iterative method.
Variations of dielectric permittivity in breast samples are distinguishable from the obtained
permittivity profiles, which is a clear indication of the presence of malignancy. Hence
microwave tomographic imaging is proposed as an alternate imaging modality for early
detection ofbreast cancer.
Bright Singh, I S; Rosamma, Philip; Chaithanya, E R; Swapna, Antony P; Afsal, V V(Elsevier, June 27, 2012)
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Abstract:
Anti-lipopolysaccharide factors (ALFs), a type of cationic antimicrobial peptides (AMPs), and their derivatives
are becoming predominant candidates for potential drugs in viral and bacterial diseases. This study
reports the first ALF from the mud crab Scylla tranquebarica (StALF, JQ899453) and the second ALF isoform
from the blue swimmer crab Portunus pelagicus (PpALF2, JQ899452). Both sequences encoded for precursor
molecules, starting with a signal peptide containing 26 amino acid residues, followed by a highly
cationic mature peptide, containing two conserved cysteine residues flanking a putative lipopolysaccharide
(LPS)-binding domain. BLAST analysis revealed that both PpALF2 and StALF exhibited significant
similarity with crustacean ALF sequences. The predicted molecular mass of the mature ALFs was 11.2 kDa
with an estimated pI of 10.0. PpALF2 and StALF also showed the typical pattern of alternating hydrophobic
and hydrophilic residues in their putative disulphide loop, suggesting that they comprise the same
functional domain. Phylogenetic analysis showed that PpALF2 and StALF have similar evolutionary status
and they were phylogenetically ancient immune effector molecules which may play an essential role in
the host defense mechanism. The spatial structures of PpALF2 and StALF possessed four beta-strands and
two alpha-helices. The results indicated that there were more than one ALF involved in crab immunity
against various pathogens. ALFs would provide candidate promising therapeutic or prophylactic agents
in health management and diseases control in crustacean aquaculture
Bijoy, Nandan S; Subhash Babu, K K(Magnolia Press, December 6, 2010)
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Abstract:
Two new clam shrimp species belonging to the genera Eulimnadia Packard, 1874 and Leptestheria Sars 1898 from Kerala, India are described. Spinicaudatan clam shrimp are among the least studied groups in India, with only 30 species reported. Eulimnadia azisi sp. nov. was collected from rain fed, temporary, rocky depressions at Vettilapara, in Western Ghats, Kerala. No males were observed and the population may be hermaphroditic. Leptestheria dumonti sp. nov. was collected from the paddy fields at Parapukara, Kerala. Altogether two species of Leptestheria and nine species of Eulimnadia have been reported from India, and this is the first report of the genus Leptestheria from Kerala.
Mohammed Yusuff, K K; Varsha, Gopalakrishnan; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Digna, Varghese; Leeju, P; Jayachandran, V P(Elesvier,Tetrahedron Letters (2010), February 15, 2010)
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Abstract:
An efficient one-pot synthesis of two new heterocyclic perimidines 4-(2,3-dihydro-1H-perimidin-2-yl)-2-methoxyphenol and
2-(quinoxalin-2-yl)-2,3-dihydro-1H-perimidine in good yields is presented. This methodology provides a simple, straightforward synthetic
route to these interesting classes of heterocycles. Crystal structure, solvatochromism and antibacterial activity of these organic compounds
are discussed.
Mohammed Yusuff, K K; Digna, Varghese; Arun, Vasudevan; Robinson, P P; Manju, Sebastian; Leeju, P; Varsha, Gopalakrishnan(International Union of Crystallography, Acta Crystallographica Section C ,Crystal Structure Communications, November 11, 2009)
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Abstract:
The Schiff base compounds N,N0-bis[(E)-quinoxalin-2-ylmethylidene]
propane-1,3-diamine, C21H18N6, (I), and N,N0-bis[(E)-
quinoxalin-2-ylmethylidene]butane-1,4-diamine, C22H20N6,
(II), crystallize in the monoclinic crystal system. These
molecules have crystallographically imposed symmetry.
Compound (I) is located on a crystallographic twofold axis
and (II) is located on an inversion centre. The molecular
conformations of these crystal structures are stabilized by
aromatic pye stacking interactions.
Alex,A V; Jacob, Philip(Cochin University of Science and Technology, May , 2001)
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Abstract:
Ultrasonic is a good tool to investigate the elastic properties of crystals. It enables one to determine all the elastic constants, Poisson’s ratios, volume compressibility and bulk modulus of crystals from velocity measurements. It also enables one to demonstrate the anisotropy of elastic properties by plotting sections of the surfaces of phase velocity, slowness, group velocity, Young’s modulus and linear compressibility along the a-b, b-c and a-c planes. They also help one to understand more about phonon amplification and help to interpret various phenomena associated with ultrasonic wave propagation, thermal conductivity, phonon transport etc. Study of nonlinear optical crystals is very important from an application point of view. Hundreds of new NLO materials are synthesized to meet the requirements for various applications. Inorganic, organic and organometallic or semiorganic classes of compounds have been studied for several reasons. Semiorganic compounds have some advantages over their inorganic and inorganic counterparts with regard to their mechanical properties. High damage resistance, high melting point, good transparency and non-hygroscopy are some of the basic requirements for a material to be suitable for device fabrication. New NLO materials are being synthesized and investigation of the mechanical and elastic properties of these crystals is very important to test the suitability of these materials for technological applications
Jacob, Philip; Alex,A V(Indian Academy of Sciences, January , 2004)
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Abstract:
Certain organic crystals are found to possess high non- linear optical coefficients,often one to two orders of magnitude higher than those of the well known inorganic non-linear optical materials.Benzoyl glycine is one such crystal whose optical second-harmonic generation efficiency is much higher than that of potassium dihydrogen phosphate. Single crystals of benzoyl glycine are grown by solvent evaporation technique using N,N-dimethyl formamide as the solvent.All the nine second-order elastic stiffness constants of this orthorhombic crystal are determined from ultrasonic wave velocity measurements employing the pulse echo overlap technique.The anisotropy of elastic wave propagation in this crystal is demonstrated by plotting the phase velocity, slowness,Young's modulus and linear compressibility surfaces along symmetry planes.The volume compressibility, bulk modulus and relevant Poisson's ratios are also determined. Variation of the diagonal elastic stiffness constants with temperature over a limited range are measured and reported.
Godfrey,Louis; Jacob, Philip(Department of Physics, 1994)
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Abstract:
The thesis investigated the elastic properties and phase transitions in selected mixed sulphate crystals – Lithium Hydrazinium Sulphate [LiN2H2SO4], Lithium Ammonium Sulphate [LiNH4SO4] and Lithium Potassium Sulphate [LiKSO4] – using ultrasonic technique. The pulse echo overlap technique has been used for measuring ultrasonic velocity and its dependence on temperature along different directions with waves of longitudinal and transverse polarizations. Two major numerical techniques and the corresponding computer programs developed as part of present work are presented in this thesis. All the 9 elastic constants of LHS are determined accurately from ultrasonic measurements and applying misorientation correction refines the constants. Ultrasonic measurements are performed in LAS to determine the elastic constants and to study the low temperature phase transitions. Temperature variation studies of elastic constant of LAS are performed for 6 different modes of propagation for heating and cooling at low temperatures. All the 5 independent elastic constants of LPS is determined using ultrasonic measurements. It is concluded that LPS crystal does not undergo a phase transition near this temperature. A comparison of the three crystals studied shows that LPS has maximum number of phase transitions and LHS has the least number. It is interesting to note that LPS has the simplest formula unit among the three. There is considerable scope for the future work on these crystals and others belonging to the sulphate family.
Kannan, Balakrishnan; Simily, Joseph; Balachandran Nair, M R; Reji, Rajan Varghese(MECS, May , 2013)
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Abstract:
Speckle noise formed as a result of the coherent nature of ultrasound imaging affects the lesion detectability. We have proposed a new weighted linear filtering approach using Local Binary Patterns (LBP) for reducing the speckle noise in ultrasound images. The new filter achieves good results in reducing the noise without affecting the image content. The performance of the proposed filter has been compared with some of the commonly used denoising filters. The proposed filter outperforms the existing filters in terms of quantitative analysis and in edge preservation. The experimental analysis is done using various ultrasound images
Description:
I.J. Information Technology and Computer Science, 2013, 06, 1-9
Deepti Das, Krishna; Gopikrishna, M; Aanandan,C K; Mohanan, P; Vasudevan, K(Electronics Letters, August , 2008)
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Abstract:
An ultra-wideband (UWB) printed slot antenna, suitable for integration with the printed circuit board (PCB) of a wireless universal serial-bus (WUSB) dongle is presented. The design comprises a near-rectangular slot fed by a coplanar waveguide printed on a PCB of width 20 mm. The proposed design has a large bandwidth covering the 3.1-10.6 GHz UWB band, unaffected by the ground length, and omnidirectional radiation patterns. A linear phase response throughout the band further confirms its suitability for high-speed wireless connectivity.
Deepti Das, Krishna; Gopikrishna, M; Aanandan,C K; Mohanan, P; Vasudevan, K(Wiley InterScience, June , 2009)
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Abstract:
A compact ultra-wideband (UWB) printed slot antenna is described, suitable for integration with the printed circuit board (PCB) of a wireless, universal, serial-bus dongle. The design comprises of a near-rectangular slot fed by a coplanar waveguide (CPW) printed on a PCB of size 20 × 30 mm2. It has a large bandwidth covering the 3.1–10.6 GHz UWB band, with omnidirectional radiation patterns. Further, a notched band centered at 5.45 GHz wireless local area network bands is obtained within the wide bandwidth by inserting a narrow slot inside the tuning stub. Details of the antenna design are described, and the experimental results of the constructed prototype are presented. The time domain studies on the antenna shows a linear phase response throughout the band except at the notched frequency. The transient analysis of the antenna indicates very little pulse distortion confirming its suitability for high speed wireless connectivity.
Kannan, Balakrishnan; Jomy, John; Pramod, K V(Elsevier, December 31, 2012)
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Abstract:
This paper presents the application of wavelet processing in the domain of handwritten character recognition. To
attain high recognition rate, robust feature extractors and powerful classifiers that are invariant to degree of variability
of human writing are needed. The proposed scheme consists of two stages: a feature extraction stage, which is based
on Haar wavelet transform and a classification stage that uses support vector machine classifier. Experimental results
show that the proposed method is effective
Prabha, C; Dr.Pillai, P R S(Cochin University of Science And Technology, July 24, 2013)
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Abstract:
Underwater target localization and tracking attracts tremendous research interest due to various impediments to the estimation task caused by the noisy ocean environment. This thesis envisages the implementation of a prototype automated system for underwater target localization, tracking and classification using passive listening buoy systems and target identification techniques. An autonomous three buoy system has been developed and field trials have been conducted successfully. Inaccuracies in the localization results, due to changes in the environmental parameters, measurement errors and theoretical approximations are refined using the Kalman filter approach. Simulation studies have been conducted for the tracking of targets with different scenarios even under maneuvering situations. This system can as well be used for classifying the unknown targets by extracting the features of the noise emanations from the targets.
Description:
Department of Electronics, Cochin University of Science and Technology.
Harikrishnan, K P; Nandakumaran, V M(Elsevier, December 7, 1987)
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Abstract:
We study the period-doubling bifurcations to chaos in a logistic map with a nonlinearly modulated parameter and show that the bifurcation structure is modified significantly. Using the renormalisation method due to Derrida et al. we establish the universal behaviour of the system at the onset of chaos.