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Field investigations of the Deccan Trap lava sequence along a 70 km traverse in the Narsingpur-Harrai-Amarwara area of central
India indicate twenty lava flows comprising a total thickness of around 480 m. Primary volcanic structures like vesicles and
cooling joints are conspicuous in this volcanic succession and are used to divide individual flows into three well-defined
zones namely the lower colonnade zone, entablature zone, and the upper colonnade zone. The variable nature of these structural
zones is used for identification and correlation of lava flows in the field. For twenty lava flows, the thicknesses of upper
colonnade zones of eight flows are ∼5 m while those of eight other flows are ∼8 m each. The thicknesses of upper colonnade
zones of remaining four flows could not be measured in the field. Using the thicknesses of these upper colonnade zones and
standard temperature-flow thickness-cooling time profiles for lava pile, the total cooling time of these sixteen Deccan Trap
lava flows has been estimated at 12 to 15 years. 相似文献
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In this work, we have considered a model of the flat Friedmann–Robertson–Walker (FRW) Universe filled with cold dark matter
and a chameleon field where the scale function is taken as (i) intermediate expansion and (ii) logamediate expansion. In both
cases we find the expressions of the chameleon field, chameleon potential, statefinder parameters, and slow-roll parameters.
Also, it has been shown that the potential always decreases with the chameleon field in both scenarios. The nature of the
slow-roll parameters has been shown diagrammatically. 相似文献
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Sahana Paul A. Hazra U. K. De S. Bhar K. Goswami 《Journal of Atmospheric Chemistry》2006,53(2):155-168
Nucleation properties of different alcoholic solutions of Benzoin and Benzoin dust have been studied by varying the seeding temperature in a laboratory Cold Chamber. In the present study, three different alcoholic solutions are being used and these are due to the standard Ethyl alcohol, one higher alcohol i.e. Isopropyle alcohol and one lower alcohol i.e. Methyl alcohol. In addition, Benzil dust and droplets of Acetone and Chloroform have been used to examine if these agents have any ice nucleation ability. It has been observed that all alcoholic solutions of Benzoin have sufficient ice nucleation ability at the negative side of 0°C, with the maximum concentration occurring at −14.4°C. In case of Benzoin dust, the nucleation ability is better on the positive side of 0°C than the negative side. On the other hand, Benzil dust has insignificant nucleation ability and the droplets of two other agents have no nucleation ability at all.Considering the chemical as well as crystalline structure, one can conclude that the presence of OH group in the seeding molecule plays the central role in ice nucleation/hydrate crystal formation. In fact, a number of supplementary experiments like crystal growth in an incubator, XRD analysis and NMR study are performed to identify the nature of crystals formed by Benzoin dust above 0°C. One can conclude that these are hydrate crystals of Benzoin with water caging around Benzoin crystals. 相似文献
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Agriculture in India is highly sensitive to climatic variations particularly to rainfall and temperature; therefore, any change in rainfall and temperature will influence crop yields. An understanding of the spatial and temporal distribution and changing patterns in climatic variables is important for planning and management of natural resources. Time series analysis of climate data can be a very valuable tool to investigate its variability pattern and, maybe, even to predict short- and long-term changes in the series. In this study, the sub-divisional rainfall data of India during the period 1871 to 2016 has been investigated. One of the widely used powerful nonparametric techniques namely wavelet analysis was used to decompose and de-noise the series into time–frequency component in order to study the local as well as global variation over different scales and time epochs. On the decomposed series, autoregressive integrated moving average (ARIMA) and artificial neural network (ANN) models were applied and by means of inverse wavelet transform, the prediction of rainfall for different sub-divisions was obtained. To this end, empirical comparison was carried out toward forecast performance of the approaches namely Wavelet-ANN, Wavelet-ARIMA, and ARIMA. It is reported that Wavelet-ANN and Wavelet-ARIMA approach outperforms the usual ARIMA model for forecasting of rainfall for the data under consideration. 相似文献
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The newer dolerite dykes around Keonjhar within the Singbhum Granite occur in NE–SW, NW–SE and NNE–SSW trends. The mafic dykes of the present study exhibit several mineralogical changes like clouding of plagioclase feldspars, bastitisation of orthopyroxene, and development of fibrous amphibole (tremolite–actinolite) from clinopyroxene, which are all considered products of hydrothermal alterations. This alteration involves addition and subtraction of certain elements. Graphical analyses with Alteration index and elemental abundances show that elements like Rb, Ba, Th, La and K have been added during the alteration process, whereas elements like Sc, Cr, Co, Ni, Si, Al, Fe, Mg and Ca have been removed. It is observed that in spite of such chemical alteration, correlation between major and trace elements, characteristic of petrogenetic process, is still preserved. This might reflect systematic Alteration (addition or subtraction) of elements without disturbing the original element to element correlation. It has also been established by earlier workers that the evolution of newer dolerite had occurred in an arc-back arc setting which may also be true for newer dolerites of the present study. This is evident from plots of pyroxene composition and whole rock composition of newer dolerite samples in different tectonic discrimination diagrams using immobile elements. The newer dolerite dykes of the Keonjhar area may thus be considered to represent an example of hydrothermal activity on mafic rocks in an arc setting. 相似文献
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Chitra Arora B. Prasad Kumar Indu Jain Ashoke Bhar A. C. Narayana 《Marine Geodesy》2013,36(2-3):261-281
The development of a theoretical model for estimating bottom boundary layer characteristics in the Hooghly estuary, located in the east coast of India, under combined effects of waves and currents is reported. Three numerical models, viz a depth averaged hydrodynamic model, SWAN wave model, and bottom boundary layer model, were integrated. In the bottom boundary layer parameters, maximum bottom stress, effective friction factor, and near-bed velocity both during ebb and flood phases of the tidal forcing are investigated and validated for the Haldia channel. The close match seen from results signifies applicability of this model for entire Hooghly basin. 相似文献
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By introducing an asymmetry between the two hemispheres, we study whether the solar dynamo solutions in the two hemispheres
remain coupled with each other. Our calculations are based on the solar dynamo code SURYA, which incorporates the helioseismically-determined
solar-rotation profile, a Babcock–Leighton α effect concentrated near the surface, and a meridional circulation. When the magnetic coupling between the hemispheres is
enhanced by either increasing the diffusion or introducing an α effect distributed throughout the convection zone, we find that the solutions in the two hemispheres evolve together with
a single period even when we make the meridional circulation or the α effect different in the two hemispheres. On the other hand, when the hemispheric coupling is weaker for other values of parameters,
an asymmetry between the hemispheres can make solutions in the two hemispheres evolve independently with different periods. 相似文献