Jacob, Philip; Manivannan, S; Dhanuskodi, S; Tiwari, S K(Springer, 2008)
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Abstract:
N-alkyl-2,6-dimethyl-4(1H)-pyridinones, salts of
4-dimethylaminopyridine and 2-amino-5-nitropyridine are considered
to be potential candidates for nonlinear optical (NLO)
applications, in particular for the generation of blue-green laser
radiation. Single crystals were grown following the slow evaporation
technique at constant temperature. Single-shot laserinduced
surface damage thresholds in the range 3–10 GW/cm2
were measured using a 18 ns Q-switched Nd:YAG laser. The
surface morphologies of the damaged crystals were examined
under an optical microscope and the nature of damage identified.
The Vicker’s microhardness was determined at a load of
98.07 mN. The thermal transport properties, thermal diffusivity
(α), thermal effusivity (e), thermal conductivity (K) and heat
capacity (Cp), of the grown crystals were measured by an improved
photopyroelectric technique at room temperature. All
the results are presented and discussed.
Kishore, V C; Dr. Sudha Kartha, C; Dr. Sreekumar, K(Cochin University of Science & Technology, June , 2008)
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Abstract:
This Thesis discussed molecules suitable for photorefractive effect. Out
of the molecules studied, only one system was used to make photorefractive polymers system. Other molecules, especially, the electro-optic
polymer, Poly(3-methacrloyl-1-(4'-nitro-4-azo-1'-phenyl)phenylalanine-co-
methyl methacrylate) can be subjected to more detailed studies to explore
the possibilities of using them for electro-optic applications. Though not included in the thesis, the efficient photoconductor, Poly(6-tert-butyl-3-
phenyl-3,4-dihydro-2H-1,3-benzoxazine) sensitized with C60, which was described in Chapter 3 showed a low magnitude photovoltaic effect. This
hints at the possibility of using this system for organic solar cells also. The thesis presented the initial observation of photorefractive effect in
a polybenzoxazine based polymer system. A detailed analysis of the effect of C60, ECZ and DR1 can be carried out to check for the possibility of a high efficiency photorefractive system.
Description:
Applied Optics Division, Department of Physics, Cochin University of Science and Technology
Radhakrishnan, P; Girijavallabhan, C P; V P N Nampoori; Thomas, K J; Sheeba, M(Journal of Optics A: Pure and Applied Optics, March 27, 2008)
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Abstract:
Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process.
The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser
emitting at 532 nm and a CCD-spectrograph in the 400–3800 cm−1 range. The variation of the
Raman intensity with the length of the optical fibre is studied. Investigations are carried out on
the variation of FWHM of the Raman peak at 2957 cm−1 with the length of the optical fibre and
pump power. The differential scattering cross section and gain coefficient of the Raman peak at
2957 cm−1 in PMMA are calculated in relation to that of toluene.
Aparna,Lakshmanan S; Vijayakumar,A(Department of Mathematics, 2008)
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Abstract:
In this paper, two notions, the clique irreducibility and clique vertex
irreducibility are discussed. A graph G is clique irreducible if every
clique in G of size at least two, has an edge which does not lie in any
other clique of G and it is clique vertex irreducible if every clique in G
has a vertex which does not lie in any other clique of G. It is proved
that L(G) is clique irreducible if and only if every triangle in G has a
vertex of degree two. The conditions for the iterations of line graph,
the Gallai graphs, the anti-Gallai graphs and its iterations to be clique
irreducible and clique vertex irreducible are also obtained.
Prasanth A, Pillai; Dr.Mohankumar, K(Cochin University of Science & Technology, October , 2008)
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Abstract:
The present study illustrates the biennial oscillation in different ocean-atmosphere
parameters associated with interannual variability of Indian summer monsoon rainfall.It also accounts the role of different processes like ENSO, IOD, QBO and ISO in the monsoon variability during the TBO years.
Description:
Department of Atmospheric Sciences,
Cochin University of Science and Technology
Gibinkumar, T R; Dr.Boopendranath, M R(Cochin University of Science & Technology, July , 2008)
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Abstract:
In the context of Indian fisheries there is a paucity of information on bycatch, in general, and bycatch reduction technologies, in particular. In this study, a detailed investigation on trawl bycatch and bycatch reduction measures is attempted with a view to evolve optimized BRDs for improving selectivity of commercial shrimp trawls. The objectives of the study included design and development of hard bycatch reduction devices (BRDs), comparative evaluation of hard bycatch reduction devices, for selective trawling, bycatch characterisation of the trawl landings, off Central Kerala; and investigations on status of the existing trawling systems operated off Central Kerala.
Description:
School of Industrial Fisheries, Cochin University of Science and Technology
V P N Nampoori; Litty, Irimpan; Bindu, Krishnan; Radhakrishnan, P(Elsevier Journal of Colloid and Interface Science, April 29, 2008)
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Abstract:
In this article we present the spectral and nonlinear optical properties of ZnO–TiO2 nanocomposites prepared
by colloidal chemical synthesis. Emission peaks of ZnO–TiO2 nanocomposites change from 340 nm
to 385 nm almost in proportion to changes in Eg. The nanocomposites show self-defocusing nonlinearity
and good nonlinear absorption behaviour. The nonlinear refractive index and the nonlinear absorption
increase with increasing TiO2 volume fraction at 532 nm and can be attributed to the enhancement of
exciton oscillator strength. ZnO–TiO2 is a potential nanocomposite material for the tunable light emission
and for the development of nonlinear optical devices with a relatively small limiting threshold
Kailasnath, M; V P N Nampoori; Radhakrishnan, P; Nishant Kumar; Bikas, Ranjan(PHOTONICS-2008: International Conference on Fiber Optics and Photonics IIT Delhi, India, December , 2008)
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Abstract:
The direction dependant wavelength selective transmission mechanism in poly (methyl
methacrylate)(PMMA) rods doped with C 540 dye and C 540:Rh.B dye mixture as a combination has been
investigated. When a polished slice of pure C 540 doped polymer rod was used side by side with a C540:Rh B
doped rod with acceptor concentration [A] = 7x10-4 m/l , we could notice more than 100% change in the
transmitted intensity along opposite directions at the C 540, Rh B emission and the excitation wavelengths . A
blue high bright LED emitting at a peak wavelength 465nm was used as the excitation source.