On magneto-hydrodynamic disturbances in a fluid in contact with a fixed plane     

Dilip Kumar Sinha 《Pure and Applied Geophysics》1969,72(1):193-197

Summary The Laplace-transform techniques have been made use of in investigating the disturbances in a conducting fluid in contact with a fixed plane.  相似文献   

Environmental evaluation of medchal taluk,Andhra Pradesh using aerial photographs     

S. M. Ramaswamy  Manohar Sinha  C. Devprasad 《Journal of the Indian Society of Remote Sensing》1984,12(2):39-46

The human interaction with nature in the form of improper exploitation and unplanned utilisation of natural resources has caused a lot of environmental imbalance in nature. The aerial photographs and other repetitive orbital remote sensing data provide valuable information in identification and surveying of such environmentally imbalanced zones. In this study the aerial photographs were used in identifying such vulnerable areas and some remedial measures are suggested for the planned exploitation of natural resources without damaging the environment.  相似文献   

Application of the dynamic initialization technique to a primitive equation model     

Dr. Subroto Sinha  P. L. Kulkarni 《Meteorology and Atmospheric Physics》1982,31(1-2):91-104

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Photogeomorphology of the Andman Coast     

P. V. L. P. Babu  S. Sinha 《Journal of the Indian Society of Remote Sensing》1982,10(2):13-22

Photogeomorphic studies of the Andaman coast reveal several landforms suggestive of coastal emergence and submergence in the recent past. Elevated reefel terrace, planation surfaces and escarpments indicate that the west coast is rising associated with a corresponding tilt of the islands in general to the east. Offshore structures in the west coast shelf and a few exposed structures in the main land are recommended for future exploration.  相似文献   

Projected climate change impacts on vegetation distribution over Kashmir Himalayas   总被引：1，自引：0，他引：1  

Irfan Rashid  Shakil Ahmad Romshoo  Rajiv Kumar Chaturvedi  N. H. Ravindranath  Raman Sukumar  Mathangi Jayaraman  Thatiparthi Vijaya Lakshmi  Jagmohan Sharma 《Climatic change》2015,132(4):601-613

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Toroidal quarter waves in the Earth’s magnetosphere: theoretical studies     

Jayashree Bulusu  A. K. Sinha  Geeta Vichare 《Astrophysics and Space Science》2014,353(2):395-404

An analytic model has been developed for toroidal quarter wave (QW) oscillations in the Earth’s magnetosphere using idealistic and highly asymmetric ionospheric boundary condition. The background magnetic field is dipolar and plasma density distribution is governed by a power law 1/r ^m where r is the geocentric distance of any point along the field line and m is the density index. The solution thus obtained has been compared with the numerical solutions. Earlier workers had developed the analytic model for trivial 1/r ⁶ (m=6) type of plasma density distribution along the field line for which the period of the fundamental is twice that of corresponding half wave (i.e. toroidal oscillation in the symmetric ionospheric boundary). The present analytic model does reproduce this feature. In addition, it is seen that this ratio decreases for lower values of m. Moreover, for a particular value of m, this ratio shows a decreasing trend with increased harmonic number. The spatial characteristics of QW obtained from present analytic model are in excellent agreement with those computed numerically, thereby validating the model. The departure of frequency computed analytically from that obtained numerically is significant only for the fundamental and this departure reduces sharply with the increased harmonic number. It should be noted that there is no such departure for 1/r ⁶ type of plasma density distribution and spatial structures as well as frequency computed from the present analytic model match perfectly with those computed numerically.  相似文献   

A note on brine layer spacing of first‐year sea ice     

M. Nakawo  N.K. Sinha 《大气与海洋》2013,51(2):193-206

Abstract

Brine layer spacing has been measured in a core sample taken 19 January 1978 from Eclipse Sound, Baffin Island, Canada. Observations on snow and ice conditions and a record of air temperatures for the entire growth season allowed correlation of the brine layer spacing with the growth rate of the sea ice. Growth rate is related to climatology, and the vertical brine layer spacing profile in the ice provides a record of previous weather conditions. It is suggested that the spacing is inversely proportional to the growth rate, and could also be dependent on crystallographic orientation. The spacing decreased rapidly with depth near the bottom of the core sample, and this is not compatible with a general relation between spacing and growth rate. Before a definitive statement can be made, cores from a variety of locations, grown in a range of meteorological conditions, will have to be studied.  相似文献   

Trends in seasonal temperatures over the Indian region   总被引：1，自引：0，他引：1  

Nilesh K Wagholikar  K C Sinha Ray  P N Sen  P Pradeep Kumar 《Journal of Earth System Science》2014,123(4):673-687

An investigation has been carried out to identify the trends in maximum, minimum and mean temperatures and temperature range over the Indian land mass during the winter (January, and February), pre-monsoon (March–May), southwest monsoon (June–September) and post-monsoon (October–December) seasons by using high resolution daily gridded data set prepared by India Meteorological Department for the period of 1969–2005. It has been observed that the maximum temperatures over the west coast of India show rising trend in winter, southwest monsoon and post-monsoon seasons but the maximum temperatures do not show any significant trend over the other parts of the country. Minimum temperatures show increasing trend over the North Indian states in all seasons and they show an increasing trend over the west coast of India in winter and southwest monsoon seasons. Mean temperature shows an increasing trend over the west coast of India during winter and southwest monsoon seasons. Decreasing trend is observed in the temperature range over North India in all seasons due to increasing trend in minimum temperature.  相似文献   

Geochemical coupling of uranium and phosphorous in soils overlying an unmined uranium deposit: Coles Hill, Virginia   总被引：2，自引：0，他引：2  

James L. Jerden  Jr.  A.K. Sinha 《Journal of Geochemical Exploration》2006,91(1-3):56-70

The mineralogy and geochemistry of soils developed over the unmined Coles Hill uranium deposit (Virginia) were studied to determine how phosphorous influences the speciation of uranium in oxidizing soil/saprolite systems typical of the eastern US. Results from this study have implications for both uranium remediation (e.g. in situ stabilization) and uranium resource exploration (e.g. near-surface geochemical sampling). The primary uranium ore (coffinite and uraninite hosted in quartzo-feldspathic gneiss) weathers to saprolites containing the same uranium concentration as the underlying ore (approximately 1000 mg U/kg saprolites). In these water saturated (below water table) saprolites the uranium is retained as uranyl phosphates of the meta-autunite group (mainly meta-uranocircite). Above the water table the soils overlying the deposit contain approximately 200 mg uranium per kg soil (20 times higher than uranium concentrations in similar soils formed from unmineralized rocks adjacent to the deposit). In these unsaturated zone soils uranium is retained by two processes: (1) incorporation into barium–strontium–calcium aluminum phosphate minerals of the crandallite group (mainly gorceixite), and (2) sorption of uranium with phosphorous onto iron oxides that coat the surfaces of other soil minerals.Thermodynamic calculations suggest that the meta-autunite group minerals present in the saprolites below the water table are not stable in the unsaturated zone soils overlying the deposit due to the drop in soil pH from  6.0 down to  4.5. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group minerals react to form U(VI)-bearing aluminum phosphates and U(VI) surface complexes or nano-precipitates associated with ferric oxides. These results therefore indicate that models predicting U(VI) speciation in phosphate amended soils must simultaneously account for variations in pH, ion activities (aluminum appears to be particularly important) and surface complexation with iron oxide mineral surfaces.  相似文献   

The subsurface megascopic characteristics of basalt and basement rocks from Koyna-Warna area of Maharashtra,India     

D. K. Sinha  Anjan Som  Sukanta Roy 《Journal of the Geological Society of India》2017,90(6):761-768

Vertical deep boreholes of depth up to 1522.50m have been drilled in Koyna-Warna area of Maharashtra State within the Deccan Volcanic Province to study the most outstanding example of Reservoir Triggered Seismicity (RTS). The drilling of 9 bore-holes in the area has provided a window to earth scientists to peep into geological details available below Deccan Trap.The 932.50m thick pile of Deccan basalt, consisting of 30 flows at Rasati, near Koyna, which has been physically seen through cores, present a marvellous geological repository for observations. The megascopic characteristics of various flows and variation in composition have been presented in this paper. The microscopic and geochemical characteristics have been kept out of this communication, as the relevant studies are not completed to draw any conclusion. This study records the presence of granite wash (≈1m thick) over basement and below basalt representing Late Archaean to Cretaceous period hiatus. The basement rocks, presumably of Late Archaean age have been described mega-scopically. A fair picture of sub-surface pre-Deccan topography is shown with the help of borehole data, which confirm the nearly flat topography of pre-Deccan surface especially in this part of the area occupied by 30 flows of Deccan basalt. Correlation of 30 flows with the established stratigraphy has also been attempted for subsurface existence of Ambenali (Upper) and Poladpur Formations of Wai Subgroup in Koyna-Warna area.  相似文献