Water resource accounting for an iron-ore mining area in India

A study has been conducted at the Bicholim iron-ore mine, North Goa, India to investigate the hydrogeological continuity between the mine's open pit and surrounding villages. Water resource accounting by demarcating different watersheds has also been carried out to analyse the major causes of groundwater scarcity in the region during dry periods. A resistivity survey and a ground penetrating radar survey were completed around the periphery of open pits, the surrounding village areas and Mayem Lake. The results of the two independent surveys and other related data confirm that there is no observable hydrogeological continuity between the pits, nearby villages and Mayem Lake. Hence, there may not be any significant effect on surrounding water resources due to mining or mine dewatering. Water resource accounting has revealed that only 15–20% of 3500 mm precipitation per annum becomes part of the groundwater resource. The remainder of the annual precipitation is lost as heavy runoff, evapotranspiration and subsurface capillary moisture. Closely spaced wells in the region have also aggravated the groundwater scarcity problem due to draw down effects. Therefore, an effective water resource conservation plan is required for the region to overcome the problem. Received: 18 January 1999 · Accepted: 17 May 1999     

Spherical Domain Walls in Higher Dimension

We have presented a spherically symmetric domain wall in five dimensionalspace-time with non-vanishing stress component in the directionperpendicular to the plane of the wall. The general solution to Einstein'sequations for such domain wall is obtained using functional separabilityof metric coefficients.     

Estimation of mean grain size of seafloor sediments using neural network

The feasibility of an artificial neural network based approach is investigated to estimate the values of mean grain size of seafloor sediments using four dominant echo features, extracted from acoustic backscatter data. The acoustic backscatter data were collected using a dual-frequency (33 and 210 kHz) single-beam, normal-incidence echo sounder at twenty locations in the central part of the western continental shelf of India. Statistically significant correlations are observed between the estimated average values of mean grain size of sediments and the ground-truth data at both the frequencies. The results indicate that once a multi-layer perceptron model is trained with back-propagation algorithm, the values of mean grain size can reasonably be estimated in an experimental area. The study also revealed that the consistency among the estimated values of mean grain size at different acoustic frequencies is considerably improved with the neural network based method as compared to that with a model-based approach.     

Junction conditions and consequences of quasi-spherical space-time with electro-magnetic field and Vaidya metric

In this work the junction conditions between the exterior Reissner-Nordstrom-Vaidya space-time with the interior quasi-spherical Szekeres space-time have been studied for analyzing gravitational collapse in the presence of a magneto-hydrodynamic fluid undergoing dissipation in the form of heat flow. We have discussed about the apparent horizon and have evaluated the time difference between the formation of apparent horizon and central singularity.      

Modeling Dust Jets And Shells From Comet Hale-Bopp

Persistent jet and shell structures from comet Hale-Bopp showing gradual changes in the shapes and orientations with aspect angle and solar illumination geometry indicate long lived active sources. A model to simulate the dust features has been applied to the series of observations from September 1996 to May 1997. Most of the structures can be explained as arising due to ejections from persistent active regions at comet-o-centric latitudes near +65°, +55°, −5° to −15°, −35° and −65°. The best fitting pole positions vary between 255° ±10° and 275° ± 10° in right ascension and −45° ± 10° to −75° ± 10° in declination. Lower limits on the dust and gas production rates at various epochs are presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

String membranes in higher dimensions

We shall study homogeneous and isotropic clouds formed of String membranes. These membranes are considered in extra dimensions of a higher dimensional Bianchi-I space-time. Some solutions are found for the field equations of the system.     

Propagation of plane relativistic shock waves in the presence of a magnetic field

In this paper we obtain similarity solutions for the propagation of plane relativistic shock waves in the presence of a transverse magnetic field for the medium, where the nucleon number density obeys a power law of distance from the plane of explosion. The shock surface moves with constant velocity and the total energy of the disturbance is dependent on time. The solutions are applicable only to an isothermal medium or a cold gas.     

Is the outcrop topology of dolerite dikes of the Precambrian Singhbhum Craton fractal?

In the Precambrian Singhbhum Craton of eastern India, newer dolerite dikes occur profusely with varying outcrop lengths. We have analysed the nature of their length-size and orientation distributions in relation to the theory of fractals. Two orientational sets of dikes (NW-SE and NE-SW) are present. Both the sets show strongly non-power-law size distributions, as reflected in non-linear variations in logarithmic space. We analyzed thousands of data, revealing that polynomial functions with a degree of 3 to 4 are the best representatives of the non-linear variations. Orientation analysis shows that the degree of dispersions from the mean trend tends to decrease with increasing dike length. The length-size distributions were studied by simulating fractures in physical models. Experimental fractures also show a non-power-law distribution, which grossly conforms to those of the dolerite dikes. This type of complex size distributions results from the combined effects of nucleation, propagation and coalescence of fractures.     

On disturbances produced by a time-periodic twist on the surface of a spheroidal cavity

Summary The problem of disturbances in an elastic medium produced by a twist on the surface of a spheroidal cavity has been solved using spheroidal functions.     

Dynamic response of pipelines to moving loads

Vibration of buried pipelines induced by moving axial and radial loads has been studied in this paper. A thin shell model has been used for the pipeline, which is assumed to be lying in an infinite isotropic homogeneous elastic medium. In order to allow for the possible motion of the pipe out of phase with the surrounding ground a very thin layer of viscoelastic material is assumed to separate the pipe from the ground. Calculations indicate the presence of the interfacial viscoelastic layer does not influence the pipe response in a significant manner. So all the numerical results presented here are for the case when the pipe is assumed to be perfectly bonded. These show that the maximum pipewall displacements and stresses occur in a soft soil at long wavelengths.