Showing papers by "Birla Institute of Technology, Mesra published in 2003"

Influence of Anisotropy on the Love Waves in a Self-reinforced Medium

Abstract: Dispersion of Love waves is studied in a self-reinforced layer lying over an elastic non-homogeneous half space. The wave velocity equation is found to be in perfect agreement with the corresponding classical result when the anisotropic elastic parameters tend to zero. Dispersion curves for the shear wave velocity ratio and the effect of anisotropy and heterogeneity have been shown graphically. It is observed that the shear wave velocity ratio of Love waves is greater for the heterogeneous half-space than for the homogeneous one. The differences are quite distinct for the smaller values of wave numbers.

Anti - inflammatory and sedative - hypnotic activity of the methanolic extract of the leaves of mentha arvensis.

Abstract: Mentha arvensis Linn, a plant used as traditional medicine and in perfumery, has now been explored for its pharmacological activities as an anti-inflammatory and also as sedativehypnotic plant drug. The methanolic extract of the leaves after being processed, was taken for the pharmacological study. Anti-inflammatory activity was carried out on albino rats. Further, the activity was compared to that of a standard anti-inflammatory drug - nimesulide and the percent inhibition of oedema determined. The sedative hypnotic activity, when carried out on mice, showed the potentiation of pentobarbitone induced sleeping time. The data of average recovery time was analyzed to show the standard deviation from the mean.

Emergence of mesua ferrea linn. Leaf extract as a potent bactericide.

Abstract: The methanolic extract of leaves of Mesua ferrea Linn. were tested for its antibacterial potentiality against 103 various strains of bacteria including Staphylococcus aureus, Bacillus spps. Klebsiella spps., Streptococus pneumoniae, Sarcina lutea, Lactobacilus arabinosus, Escherichia coli, shigellae, salmonellae, Proteus spps., Pseudomonas spps. and the vibrios. Significant antibacterial effects were produced by the extract against Staphylococcus aureus, Bacillus sppa., lactobacilli, Escherichia coli, shigellae and salmonellae and the results were compared with standard antibiotic ciprofloxacin. Further the extract was proved to be bacterial in its action.

Erosive Burning of Ammonium Perchlorate/Hydroxyl-Terminated-Polybutadiene Propellants Under Supersonic Crossflows

Abstract: An experimental procedure adopted for measuring the erosive burning in solid propellants under transonic and supersonic crossflow Mach numbers is explained. Three formulations of ammonium perchlorate/hydroxyl-terminated-polybutadiene propellants of different burning rates (6, 9, and 16 mm/s at 5 MPa) were used for the study. The study presents the erosive burning results for a range of crossflow Mach numbers from 0.8 to 1.7. Additionally, the adopted experimental procedure clearly demonstrates the choking station movement in grain ports of nozzleless motors. As observed under subsonic crossflow conditions, in supersonic conditions the following conditions hold: 1) The erosive burning effect increases with the increase in both pressure and free stream velocity of crossflow. 2) The propellants with lower normal-burning rates experience greater erosive burning than those with higher normal-burning rates. Negative erosive burning under supersonic crossflow velocities is identified at low pressures.

Displacement and deflection of optical beams by nonlinear planar waveguide

Abstract: In this paper we investigate the propagation characteristics of an end fired Gaussian optical beam through a planar nonlinear waveguide. Using variational formalism we have derived three coupled second order dynamical equations for the beam widths and centre of gravity of the propagating optical beam. Using these equations, we have investigated numerically the beam deflection, displacement and their possible control by nonlinearity. We have shown that intensity dependent control is possible only when the waveguide core possesses nonlinearity and the substrate is linear. In addition, we have demonstrated that such control is not possible in bulk media. We have further established that setting an appropriate length of the waveguide one can achieve maximum displacement with minimum deflection or minimum displacement with maximum deflection. Possible application of our investigation in optical communication and signal processing are highlighted.

Simulation studies on the nature of fractal dimensions of glass-ceramics at percolation threshold

Abstract: We simulate the fractal dimensions (D) of glass-ceramics resulting from different glass microstructures, at their percolation thresholds. We consider only crystallisation in glasses resulting from phase separation by nucleation. Phase separation may occur at a lower temperature or at the same temperature at which crystallisation takes place. We have studied both cases. The structure-property relationship of such glass-ceramics is dictated by the evolution of the structure of crystalline phase percolation cluster. At the percolation threshold the structure of the percolation path may be quantified by its fractal dimensionality (D). The value of D displays universal behaviour for a system in the thermodynamic limit. However, it deviates owing to finite size effects. Our simulations suggest that these deviations for a given system size depend on the nature of the glass microstructure. As the value of D reaches Euclidean dimension, the system attains more compact percolation cluster. This has invariably occurred in the present investigation for fine crystalline phase microstructure.

An Infrared Technique for Rapid Analysis of Ramie-Acrylic Blends

Abstract: An analysis of ramie-acrylic blends of different blend compositions is reported using an infrared technique. Blend estimations are made from a calibration plot between the absorption of the 2235 cm - 1 band (C≡N) and the composition percentages of acrylic fibers.

An Upper Bound Solution for Closed Die Forging of Sintered Polygon

Abstract: The paper reports on an investigation into the various aspects of closed die cold forging of polygonal powder preforms, which have been compacted and sintered from atomized powder. It is found that for certain dimensional ratios of the preform the die pressure is minimum. An attempt has been made for the determination of the die pressures developed for given geometries of the disc during the closed die forging of polygonal powder preform by using an upper bound approach. Uniform frictional stresses are assumed on top and bottom interfaces and along the interfaces on sides. The feasibility of metal powder preform has been demonstrated by applying an appropriate interfacial friction law and yield criteria. The solution can be extended to closed die forging of any polygonal shape. The results of hexagonal shape is taken for illustration and results so obtained are discussed critically to illustrate the interaction of various process parameters involved and are presented graphically.