Charlotte,B V; P G Kurup(Department of Physical Oceanography, School of Marine Sciences, 2004)
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Abstract:
The study is undertaken with an objective to investigate the linkage between air-sea fluxes in the Indian Ocean and monsoon forcing. Since the monsoon activity is linked to fluxes, the variability of surface marine meteorological fields under the variable monsoon conditions is also studied. The very objective of the present study is to document various sea surface parameters of the Indian Ocean and to examine the anomalies found in them. Hence it is attempted to relate the anomaly to the variability of monsoon over India, highlighting the occasion of contrasting monsoon periods. The analysis of anomalies of surface meteorological fields such as SST, wind speed and direction, sea level pressure and cloud cover for contrasting monsoons are also studied. During good monsoon years, the pressure anomalies are negative indicating a fall in SLP during pre-monsoon and monsoon months. The interaction of the marine atmosphere with tropical Indian Ocean and its influence on ISMR continue to be an area of active research.
Anantharaman,M R; V P N Nampoori; Radhakrishnan,P; Girijavallabhan,C P; Sajan,D George; Saravanan, S; Venkatachalam,S(Physical Review, American Physical Society, June 8, 2004)
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Abstract:
Thermal diffusivity of the composites of camphor sulphonic acid (CSA) doped polyaniline (PANI) and its
composites with cobalt phthalocyanine (CoPc) has been measured using open cell photoacoustic technique.
Analysis of the data shows that the effective thermal diffusivity value can be tuned by varying the relative
volume fraction of the constituents. It is seen that polaron assisted heat transfer mechanism is dominant in CSA
doped PANI and these composites exhibit a thermal diffusivity value which is intermediate to that of CSA
doped PANI and CoPc. The results obtained are correlated with the electrical conductivity and hardness
measurements carried out on the samples
Neema,C P; Babu,C A(Department of Atmospheric Science, 2004)
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Abstract:
This study deals with the salient features of the north Indian ocean associated with the summer monsoon. The focus is given on the Arabian sea mini warm pool, which is a part of the Indian ocean. It primarily study the certain aspects of the atmosphere and ocean variability in the north Indian ocean. The attempt were made to understand various aspects of time –scale variability of major features occurring in the Indian summer monsoon. The result from the thesis can be utilized as an input for model studies for prediction of monsoon, understanding ocean dynamics, radar tracking and ranging etc.
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.
Girijavallabhan, C P; Radhakrishnan, P; V P N Nampoori; Sajan, D George; Saravanan, S; Venkatachalam, S(Physical Review, American Physical Society, June 8, 2004)
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Abstract:
Thermal diffusivity of the composites of camphor sulphonic acid (CSA) doped polyaniline (PANI) and its
composites with cobalt phthalocyanine (CoPc) has been measured using open cell photoacoustic technique.
Analysis of the data shows that the effective thermal diffusivity value can be tuned by varying the relative
volume fraction of the constituents. It is seen that polaron assisted heat transfer mechanism is dominant in CSA
doped PANI and these composites exhibit a thermal diffusivity value which is intermediate to that of CSA
doped PANI and CoPc. The results obtained are correlated with the electrical conductivity and hardness
measurements carried out on the samples.
Anupam,Chandran R; Thomaskutty,Mathew; Aanandan,C K; Mohanan,P; Vasudevan,K(Microwave and Optical Technology Letters, February 5, 2004)
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Abstract:
A novel technique for backscattering reduction for both TE
and TM polarisation, employing a metallo-dielectric structure based on
Sierpinski carpet fractal geometry, is reported. A reduction in backscattered
power of --30 dB is obtained for normal incidence in the X-band for the
structure using the third iterated stage of the fractal geometry
Jack,Wu; Qiu,S N; Shih,I(Microwave and Optical Technology Letters, November 20, 2004)
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Abstract:
Photonic band-gap (PBG) structures are utilized in microwave
components as filters to suppress unwanted signals. In this
work, rectangular perforations were created in the ground plane of a microstrip line to construct a PBG structure. A gold-coated alumina
substrate was utilized to switch or tune the bandstop characteristics of
this structure. It was demonstrated that the bandstop characteristics
were switched off from - 35 to - 1 dB at 16 GHz. Tuning of the bandstop
edge with a shift of 1.5 GHz was also shown
Dongsheng,Qi; Binhong,Li; Yabin,Zhang; Haitao,Liu(Microwave and Optical Technology Letters, February 3, 2004)
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Abstract:
A novel compact single-layer dual frequency microstrip
antenna which uses an H-shaped geometry with two U-shaped slots embedded
near the radiation edges, is presented. By changing the design parameters, the lower and higher resonant frequencies can be controlled
easily, and a range of frequency ratios (1.716-2.363) can be
obtained in this design. For the two operating frequencies of the proposed
antenna, the same polarization planes and broadside radiation
patterns are achieved. Compared to the regular dualfrequency patch
antenna, this antenna can realize a significant size reduction
Rohith,Raj K; Sona,Kundukulam O; Aanandan,C K; Vasudevan,K; Mohanan,P; Praveen,Kumar(Microwave and Optical Technology Letters, February 20, 2004)
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Abstract:
compact microstrip antenna integrated with an amplifier
having an area reduction of 70%, compared to the standard circular microstrip
patch antenna, is presented. The antenna also provides an enhanced
gain of 10-dB more than its passive counter part. The measured 2:1
VSWR band width is -4% at 790 MHz, which is 2.5 times larger than that
of the passive microstrip antenna
Lethakumary,B; Sreedevi,Menon K; Aanandan,C K; Vasudevan,K; Mohanan,P(Microwave and Optical Technology Letters, November 20, 2004)
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Abstract:
A theoretical analysis of a symmetric T-shaped rnicrostripfed
rectangular microstrip antenna using the finite-difference titnedoniain
(FDTD) method is presented in this paper. The resonant frequency,
return loss, impedance bandwidth, and radiation patterns are
predicted and are in good agreement with the measured results