Interpretation of gravity and magnetic anomalies caused due to spherical bodies

Summary The method of continuation has been used to obtain the master curves for gravity and magnetic anomalies caused by spherical bodies. The procedure to calculate the depth of burial and radius of spherical bodies has been outlined.     

Hydromorphogeological mapping of Panwari area,Hamirpur district,Uttar Pradesh using satellite data

The area around Panwari town, Hamirpur district, Uttar Pradesh, faces acute water scarcity and chronically drought prone. The groundwater resources in the area have not been fully exploited. The present study was undertaken to evaluate the groundwater prospective zones. Landsat TM and IRS-1A LISS-II data have been used to differentiate different hydromorphogeological units and to delineate the major trends of lineaments. The digitally enhanced False Colour Composite, Principal Component Analysis and Edge Detections were useful for better correlation. The digital enhancement was helpful with identification of faint lineaments. In addition, the boundaries of various lands forms were better discriminable on the digitally enhanced products. The deeply and moderately weathered buried pediplains are the most potential zones for groundwater targeting. Occurrence of lineaments in such zones is also a favourable indicator. A number of promising groundwater well sites have been located in the pediplains.     

Overcrowding: a behavioral perspective

The author discusses overpopulation as it affects public mental health by reviewing relevant literature in the fields of psychology and demography. The impact of population density in India is addressed.     

On the Electron density in a coronal hole

Electron density in a coronal hole is rediscussed using the new calculation for the Mgviii 436.62/430.47 density-sensitive theoretical line ratio and with the help of available observations.     

Geohistory analysis of Bombay High region

Geohistory diagrams have been constructed for three representative sites in the Bombay High region, Offshore West-Coast India. The model curve for 60% lithospheric injection matches the intitial part of a thermo-tectonic curve for one of the sites, where a complete Tertiary sequence is developed. The study suggests that the four Paleogene unconformities, recognised in this region, were caused by eustatic falls. A distinct phase of active subsidence occurred during the late Middle — Late Miocene, probably due to more active spreading at the Mid-Indian Ocean Ridge.     

The feasibility of a slip velocity model for predicting the enrichment of chromite in a Floatex density separator

The Floatex density separator (FDS) is an industrial separator and works on the principle of hindered settling where the settling rate of a particle in suspension is affected by nearby particles. This phenomenon of hindered settling has been described by various authors using the concept of particle slip velocity. The feasibility of one such slip velocity model proposed by Galvin et al. to predict the separation of chromite in a plant scale FDS was examined. Previously this model was validated only at lab scale with synthetic mixture of various density particles. In order to use this model, the feed chromite ore was characterized and quantified into different density mineral classes and their percentages were estimated by using mineralogical grain count method. The performance of FDS was then predicted using slip velocity model in terms of weight recoveries and composition of different minerals in the FDS underflow product.     

Forest fires monitoring using envisat-aatsr data

Forests over Indian region are fire prone during summer season and effective means for monitoring such events is important. Satellite data with its repetitive and wide area coverage provides data sets required for monitoring such events. The advances in sensor technology and multi-satellite systems have improved capability for monitoring such events. The present study addresses forest fires monitoring using night time data sets of ENVISAT-AATSR data over Indian Region. The results of the study indicated that region specific algorithms are required for forest fire detection as soils in tropical regions have higher temperatures during night time.     

Coda power and modulation characteristics of a complex P signal from underground nuclear explosions

Coda power characteristics of six underground nuclear explosions from two near by test sites of Novaya Zemlya are examined. It is shown that one of the events presenting a complex P waveform and distinctive coda power characteristics can be synthesised by superposition of two signals of simpler form from the same site. The relative P amplitudes of the two signals give a ratio of 0.7–1.0 and the relative delay of 0.8 sec. The modulation effect is clearly seen in band-pass filtered traces where a shift in the envelope maximum occurs for center frequencies between 0.6 and 0.8 Hz. The complex event is interpreted as a double explosion.     

Electrical conductivity of some Indian basalts under various temperature conditions

Electrical conductivity of nineteen samples of the Deccan Traps, collected from the Pawagarh area and two boreholes drilled at Koyna, has been measured in the temperature range from 475 K to about 1100 K. The results indicate the change of the conduction mechanism from impurity to electronic/ionic conduction as the temperature increases. Few samples show the normal behaviour, i.e. the increase of conductivity with temperature, while some samples show an anomalous behaviour between the temperatures 600 and 1000 K. This anomalous behavior may be due to either the dehydration of OH^? ions or/and the oxidation of Fe²⁺ to Fe³⁺.     

Multiple incidence angle sir-b data analysis over parts of the assam plains

SIR-B Synthetic Aperture Radar System operating at L-band (HH) acquired images over parts of the Assam plains at 25.6° and 45.2°incidence angle during October 1984. The capabilities of L-band SAR for delineating various land covers using multiple incidence angle imageries have been assessed. It was observed that colour composite image generated from multiple incidence angle imagery was useful in delineating various land cover units.