Unnikrishnan, K P; Jayan, Thomas; Nampoori, V P N; Vallabhan, C P G(Elsevier, April 1, 2002)
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Abstract:
Third order nonlinear susceptibility χ(3) and second hyperpolarizability (γ) of a bis-naphthalocyanine viz. europium naphthalocyanines, Eu(Nc)2, were measured in dimethyl formamide solution using degenerate four wave mixing at 532 nm under nanosecond pulse excitation. Effective nonlinear absorption coefficient, βeff and imaginary part of nonlinear susceptibility, Im(χ(3)) were obtained using open aperture /Z-scan technique at the same wavelength. Optical limiting property of the sample was also investigated. The role of excited state absorption in deciding the nonlinear properties of this material is discussed.
Nibu A, George; Vallabhan, C P G; Nampoori, V P N; Radhakrishnan, P(Optical Society of America, August , 2002)
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Abstract:
Photothermal beam deflection studies were carried out with GaAs epitaxial double layers grown on semi-insulating GaAs substrates. The impurity densities in thin epitaxial layers were found to influence the effective thermal diffusivity of the entire structure.
Sankar, T V; Ramachandran, A(John Wiley & Sons, 2002)
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Abstract:
The gel strength, compressibility and folding characteristic of suwari (set) and kamaboko (set and cooked) gels prepared from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) surimi were examined to understand the occurrence of suwari and modori phenomena in surimi from major freshwater carps. Suwari setting of gels did not take place at lower temperatures. Suwari gels showed good gel strength at 50 °C for rohu and at 60 °C for catla and mrigal after 30 min setting time. Incubation for 60 min decreased the gel strength at 60 °C for rohu and catla. Setting at 25 °C followed by cooking at 90 °C increased the gel strength. Increased setting temperature, however, decreased the gel strength of cooked gels. Gel strength and compressibility data were supported by folding characteristics.
Parvathi, R; Indic, P; Nampoori, V P N(Elsevier, February 11, 2002)
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Abstract:
Nonlinear time series analysis is employed to study the complex behaviour exhibited by a coupled pair of Rossler systems. Dimensional analysis with emphasis on the topological correlation dimension and the Kolmogorov entropy of the system is carried out in the coupling parameter space. The regime of phase synchronization is identified and the extent of synchronization between the systems constituting the coupled system is quantified by the phase synchronization index. The effect of noise on the coupling between the systems is also investigated. An exhaustive study of the topological, dynamical and synchronization properties of the nonlinear system under consideration in its characteristic parameter space is attempted.