Now showing items 21-32 of 32
Abstract: | The role of acoustic plasmons in the recently discovered high Tc superconductors is discussed. It is shown that the exchange of acoustic plasmons together with the usual phonon exchange between electrons can give rise to a Tc - 100 K. |
URI: | http://dyuthi.cusat.ac.in/purl/2570 |
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Dyuthi-P0129.pdf | (164.0Kb) |
Abstract: | The chaotic dynamics of directly modulated semiconductor lasers with delayed optoelectronic feedback is studied numerically. The effects of positive and negative delayed optoelectronic feedback in producing chaotic outputs from such lasers with nonlinear gain reduction in its optimum value range is investigated using bifurcation diagrams. The results are confirmed by calculating the Lyapunov exponents. A negative delayed optoelectronic feedback configuration is found to be more effective in inducing chaotic dynamics to such systems with nonlinear gain reduction factor in the practical value range. |
URI: | http://dyuthi.cusat.ac.in/purl/2529 |
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Dyuthi-P0104.pdf | (1.292Mb) |
Abstract: | A dynamical system with a damping that is quadratic in velocity is converted into the Hamiltonian format using a nonlinear transformation. Its quantum mechanical behaviour is then analysed by invoking the Gaussian effective potential technique. The method is worked out explicitly for the Duffing oscillator potential. |
URI: | http://dyuthi.cusat.ac.in/purl/2559 |
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Dyuthi-P0118.pdf | (338.5Kb) |
Abstract: | We establish numerically the validity of Huberman-Rudnick scaling relation for Lyapunov exponents during the period doubling route to chaos in one dimensional maps. We extend our studies to the context of a combination map. where the scaling index is found to be different. |
URI: | http://dyuthi.cusat.ac.in/purl/2560 |
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Dyuthi-P0119.pdf | (905.4Kb) |
Abstract: | The phenomenon of two-soliton resonances of the Kadomtsev-Petviashvilli equation for the superfluid surface density fluctuation in He films is studied. The velocity of the resonant soliton is obtained. |
URI: | http://dyuthi.cusat.ac.in/purl/2561 |
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Dyuthi-P0120.pdf | (384.2Kb) |
Abstract: | The dynamics of saturated two-dimensional superfluid4He films is shown to be governed by the Kadomtsev-Petviashvili equation with negative dispersion. It is established that the phenomena of soliton resonance could be observed in such films. Under the lowest order nonlinearity, such resonance would happen only if two dimensional effects are taken into account. The amplitude and velocity of the resonant soliton are obtained. |
URI: | http://dyuthi.cusat.ac.in/purl/2568 |
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Dyuthi-P0127.pdf | (427.3Kb) |
Abstract: | Optical emission from TiO2 plasma, generated by a nanosecond laser is spectroscopically analysed. The main chemical species are identified and the spatio-temporal distribution of the plasma parameters such as electron temperature and density are characterized based on the study of spectral distribution of the line intensities and their broadening characteristics. The parameters of laser induced plasma vary quickly owing to its expansion at low background pressure and the possible deviations from local thermodynamic equilibrium conditions are tested to show its validity. |
URI: | http://dyuthi.cusat.ac.in/purl/1821 |
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Spectral Charac ... from Titanium Dioxide.pdf | (296.3Kb) |
Abstract: | We consider the stability properties of spatial and temporal periodic orbits of one-dimensional coupled-map lattices. The stability matrices for them are of the block-circulant form. This helps us to reduce the problem of stability of spatially periodic orbits to the smaller orbits corresponding to the building blocks of spatial periodicity, enabling us to obtain the conditions for stability in terms of those for smaller orbits. |
URI: | http://dyuthi.cusat.ac.in/purl/2537 |
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Dyuthi-P0112.pdf | (184.9Kb) |
Abstract: | The effect of coupling on two high frequency modulated semiconductor lasers is numerically studied. The phase diagrams and bifurcatio.n diagrams are drawn. As the coupling constant is increased the system goes from chaotic to periodic behavior through a reverse period doubling sequence. The Lyapunov exponent is calculated to characterize chaotic and periodic regions. |
URI: | http://dyuthi.cusat.ac.in/purl/2534 |
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Dyuthi-P0109.pdf | (272.8Kb) |
Abstract: | In this Letter we numerically investigate the dynamics of a system of two coupled chaotic multimode Nd:YAG lasers with two mode and three mode outputs. Unidirectional and bidirectional coupling schemes are adopted; intensity time series plots, phase space plots and synchronization plots are used for studying the dynamics. Quality of synchronization is measured using correlation index plots. It is found that for laser with two mode output bidirectional direct coupling scheme is found to be effective in achieving complete synchronization, control of chaos and amplification in output intensity. For laser with three mode output, bidirectional difference coupling scheme gives much better chaotic synchronization as compared to unidirectional difference coupling but at the cost of higher coupling strength. We also conclude that the coupling scheme and system properties play an important role in determining the type of synchronization exhibited by the system. |
URI: | http://dyuthi.cusat.ac.in/purl/2530 |
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Dyuthi-P0105.pdf | (451.1Kb) |
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. |
URI: | http://dyuthi.cusat.ac.in/purl/2566 |
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Dyuthi-P0125.pdf | (299.5Kb) |
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. |
URI: | http://dyuthi.cusat.ac.in/purl/2571 |
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Dyuthi-P0130.pdf | (215.1Kb) |
Now showing items 21-32 of 32
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