Two-Well System under Large Amplitude Periodic Forcing: Stochastic Synchronization, Stochastic Resonance and Stability

We study the residence time distributions and explore the possibility of observing stochastic resonance and synchonization of passages in a two-well system driven by a periodic forcing of amplitude larger than a marginal value beyond which one of the two wells become unstable and diasppear. We define and calculate hysteresis loop in the system, the area of which measures the degree of synchronization between the residence time statistics and the input signal, as a function of input noise strength. We analyse the noise induced stability obtained in such a deterministically overall unstable system and within this context discuss the above two phenomena.Comment: Mod. Phys. Lett. B 1997, in print, figures available on reques

Phase stability and dynamics of entangled polymer-nanoparticle composites.

Nanoparticle-polymer composites, or polymer-nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host

AC driven thermal ratchets

We consider the motion of a overdamped Brownian particle in periodic asymmetric potential with space dependent friction coefficient. In the presence of external time periodic forcing, the system shows multiple current reversals on varying the amplitude of the external forcing and the temperature of the thermal bath. In the adiabatic regime we find a single reversal of current as a function of noise strength which can only be accounted due to the presence of space dependent friction coefficient. For very large forcing term, the current does not go to zero, instead it asymptotically tends to a limiting value depending on the phase shift between the potential and the friction. This fact plays an important role in obtaining multiple current reversals.Comment: 4 pages, latex/revtex, 4 eps figures. Proceedings of CMDAYS2K, held at Guru Ghasidas University, Bilaspur, Chattisgarh, India, Aug 29-31, 2

Stochastic resonance and nonlinear response in a dissipative quantum two-state system

We study the dynamics of a dissipative two-level, system driven by a monochromatic ac field, starting from the usual spin-boson Hamiltonian. The quantum Langevin equations for the spin variables are obtained. The amplitude of the coherent oscillations in the average position of the particle is studied in the high temperature limit. The system exhibits quantum stochastic resonance in qualitative agreement with earlier numerical results.Comment: PRB April 1997, figures available on reques

ANALYSIS OF JOB STRESS AFFECTING PERFORMANCE OF TECHNICAL TEACHERS

In this modern society job stress is a much talked complex phenomena leading to many disastrous consequences. Moderate level of stress that motivates a teacher is good. But as per the review of literature at international and national levels scenarios; some of the findings of the study reveals that majority of teachers faces serious problems of job stress due to various reasons such as work overload, lack of resources, role ambiguity, fair/less compensation, inadequate work environment etc. Also poor relations with colleagues, students’ indiscipline, lack of support from higher authorities, negative community attitude, farrago of thoughts related to profession and improper trainings contributes greatly in enhancing the problem. The quality of Technical education is serious concern of current situation which poses many issues to the future of technical youth. In this research it is tried to analyses the causes of stress and impact on quality because of stress. This will be done by designing the questionnaire depicting various reasons of stress in the educational Institutions as mentioned above. After that analysis will be done before coming the conclusion by applying various statistical methods on the data collected.  The results will help us in identifying the key factors impacting quality of Technical Teachers. Hence this research is expected to contribute towards increase in the productivity of teachers in technical education. In future this research can be applied to the teacher community as a whole.&nbsp