Torsion, Chern-Simons Term and Diffeomorphism Invariance

In the $torsion \otimes curvature$ approach of gravity Chern-Simons modification has been considered here. It has been found that Chern-Simons contribution to the bianchi identity has become cancelled from that of the scalar field part. But "homogeneity and isotropy" consideration of present day cosmology is a consequence of the "strong equivalence principle" and vice-versa.Comment: 8 page

Beyond the Horizon

Cosmic horizons arise in general relativity in the context of black holes and in certain cosmologies. Classically, regions beyond a horizon are inaccessible to causal observers. However, quantum mechanical correlations may exist across horizons that may influence local observations. For the case of de Sitter space, we show how a single particle excitation behind the horizon changes the density matrix governing local observables. As compared to the vacuum state, we calculate the change in the average energy and entropy per unit volume. This illustrates what may be a generic property allowing some features of spacetime beyond a horizon to be inferred.Comment: 9 pages, 1 figur

Relation between Stochastic Resonance and Synchronization of Passages in a Double-Well System

We calculate, numerically, the residence times (and their distribution) of a Brownian particle in a two-well system under the action of a periodic, saw-tooth type, external field. We define hysteresis in the system. The hysteresis loop area is shown to be a good measure of synchronization of passages from one well to the other. We establish connection between this stochastic synchronization and stochastic resonance in the system.Comment: To appear in PRE May 1997, figures available on reques

Effect of Silting Yield Index on Biomass and Carbon Sequestration Potential along an Altitudinal Gradient of Subtropical Chir Pine Forests and Grasslands in North Western Himalaya, India

Biomass is an important characteristic of vegetation and is regarded as an important indicator of ecological and management processes in the vegetation. Measures of standing crop also reflect the amount of energy stored in the vegetation, which can indicate the potential productivity at the site. Forests are important for carbon sequestration besides playing very important role in the global carbon cycle. They store about 80% of all aboveground and 40% of all belowground terrestrial organic carbon. This study comprises to estimate the biomass and carbon stock of chirpine forests at different altitudinal gradients

Aperiodic tumbling of microrods advected in a microchannel flow

We report on an experimental investigation of the tumbling of microrods in the shear flow of a microchannel (40 x 2.5 x 0.4 mm). The rods are 20 to 30 microns long and their diameters are of the order of 1 micron. Images of the centre-of-mass motion and the orientational dynamics of the rods are recorded using a microscope equipped with a CCD camera. A motorised microscope stage is used to track individual rods as they move along the channel. Automated image analysis determines the position and orientation of a tracked rods in each video frame. We find different behaviours, depending on the particle shape, its initial position, and orientation. First, we observe periodic as well as aperiodic tumbling. Second, the data show that different tumbling trajectories exhibit different sensitivities to external perturbations. These observations can be explained by slight asymmetries of the rods. Third we observe that after some time, initially periodic trajectories lose their phase. We attribute this to drift of the centre of mass of the rod from one to another stream line of the channel flow.Comment: 14 pages, 8 figures, as accepted for publicatio

The layer disorders defect in coir fiber under thermal and chemical treatment

Natural coir fibers, subjectd to thermal treatments in the range of 0oC to 200oC and alkali treatment with 5% to 30% concentration w/w, have been used in the present investigation to determine the interlayer variability of the cellulose planes (020), (110) and (110). Among the equatorial reflections (110), (110) and (020), the extent of variability is found to be more with the proportion of such affected planes less for (020) reflection in the native cellulose at lower temperature while at higher temperature (110) and (110) become more affected by variability defect. (110) and (1 10) planes are more affected also with alkali treatment.The layer disorders defect in coir fiber under thermal and chemical treatment D N Mahato*, B K Mathur and S Bhattacharjee Department of Physics, Indian Institute of Technology, Kharagpur-721 302, West Bengal, India E-mail : [email protected] of Physics, Indian Institute of Technology, Kharagpur-721 302, West Bengal, Indi

Flutter analysis of rotary laminated composite structures using higher-order kinematics

Abstract The flutter analysis of rotary laminated structures has been performed using Carrera Unified Formulation (CUF). CUF is a one-dimensional higher-order structural model, in which the displacement at the cross-section is the only unknown parameter. The cross-sectional displacement fields of the model are defined using the Lagrange- and Taylor expansion. The quasi-steady and unsteady theories (Theodorsen and Loewy) have been used to apply the aerodynamic force. Subsequently, the equation of motion is defined in 'fundamental nucleus' form using Hamilton's principle. The engineering solution of the flutter condition has been obtained by using p-k method. The computational studies of flutter analysis have been done for various rotor hub, lamination sequence, and structural models. The regular, irregular plies and arbitrary fiber orientation of the orthotropic structures have also been considered. The present study suggests that the proposed CUF model can obtain an aeroelastic solution of rotary structure in a computationally and economically efficient manner