Erratum to: Characterizing slope morphology using multifractal technique: a study from the western continental margin of India     

Chakraborty  Bishwajit  Karisiddaiah  S. M.  Menezes  A. A. A.  Haris  K.  Gokul  G. S.  Fernandes  W.  Kavitha  G. 《Natural Hazards》2015,77(1):127-127

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Discrimination between Babul plantations and Mustard crop using Polarimetric C- and L- band data     

R. L. Mehta  N. Parihar  A. Sinha  B. P. Shastri  M. Chakraborty 《Journal of the Indian Society of Remote Sensing》2014,42(2):439-444

Radar sensors can be used for large-scale vegetation mapping and monitoring using backscattering coefficients in different polarizations and wavelength bands. C-band space borne SAR is widely used for the classification of agricultural crops, but can only perform a limited discrimination of various tree species. This paper presents the results of discrimination between mustard crop and babul plantation (Prosopis sp.) using quad polarisation Radarsat 2 and ALOS PALSAR data. Study area is comprised of dense babul plantation along the canal, mustard crop on one side of the canal and Fallow land near to Ramgarh village of Jaisalmer district. Three bands of Radarsat (HH, HV and VV) acquired during peak mustard crop growth stage were integrated with four polarizations (HH, HV, VH and VV) of ALOS PALSAR acquired when crop cover was absent. Using only Radarsat data Jefferies-Matusita (JM) separability between mustard crop and babul plantation was found to be poor (710). Where as in the seven band combination the separability was observed to be high (1374). Among the different polarizations three layer combination, highest separability was observed using cross polarizations (HV and VH) of L-band with any one of the Radarsat Polarisation (HH/HV/VV). This combination of C- and L-band resulted in easy separation of mustard and babul plantation which was otherwise difficult using only Radarsat data.  相似文献   

Inflationary Solutions for Higher Dimensional Anisotropic Cosmological Model in Scalar-Tensor Theory II     

Subenoy Chakraborty  Tapan Kumar Ghosh 《Astrophysics and Space Science》1997,257(2):175-182

This is the second paper of the series where we have considered Brans-Dicke (B-D) theory as well as general scalar tensor theory of gravitation in higher dimensional space-time model in the false vacuum state. We have examined whether inflationary solutions are possible both for constant or variable coupling parameter ω. Also the nature of the scalar field and the coupling parameter are discussed in the asymptotic limit. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Spintessence: A Possible Candidate as a Driver of the Late Time Cosmic Acceleration     

Narayan Banerjee  Sudipta Das 《Astrophysics and Space Science》2006,305(1):25-27

In this paper, it is shown completely analytically that a spintessence model in the dust dominated universe can very well serve the purpose of providing an early deceleration and a present day acceleration.  相似文献   

Nonlinear shift of wave parameters of whistlers in the ionosphere     

S. N. Paul  G. C. Das  A. K. Sur  B. Chakraborty 《Astrophysics and Space Science》1987,129(1):123-129

The expression for nonlinear shift of a wave number of a whistler wave propagating through the ionosphere has been derived and the results have been discussed. It is seen that nonlinear shift of a wave number of a whistler is significant in some physical situations. From numerical estimations it is observed that wave number shifts of a whistler for both the LCP and RCP waves become significant when the frequency of the waves are nearly equal to the ion-cyclotron frequency.  相似文献   

Propagation of plane relativistic shock waves in a slowly moving medium     

T. K. Chakraborty 《Astrophysics and Space Science》1980,68(2):469-474

Similarity solutions for the propagation of plane relativistic shock waves in a slowly moving medium, where the nucleon number density obeys an exponential law ofx/t, is obtained in this paper. 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.  相似文献   

Tectonothermal modelling for Sikkim Himalaya: Implications for channel flow to thrust tectonics in collision zones     

Dilip K. Mukhopadhyay  Sumit Chakraborty  Somnath Dasgupta 《《地质学报》英文版》2018,92(Z1):37-37

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Record of Leaf and Pollen cf. <Emphasis Type="Italic">Sloanea</Emphasis> (Elaeocarpaceae) from the Middle Siwalik of Darjeeling sub-Himalaya,India and its Palaeobiogeographic Implications     

Sandip More  Rajarshi Rit  Mahasin Ali Khan  Dipak Kumar Paruya  Suchana Taral  Tapan Chakraborty  Subir Bera 《Journal of the Geological Society of India》2018,91(3):301-306

Fossil leaf impressions and pollen grains comparable to modern Sloanea sp. of Elaeocarpaceae collected from the middle part of the Siwalik sediments (Geabdat Sandstone Formation; Pliocene) in Darjeeling foothills of eastern Himalaya are reported in the present communication. On the basis of macro morphological features, leaf remains are described as a new species Sloanea siwalika sp. nov. This is the first authentic record of the occurrence of leaf and pollen grains comparable to the genus Sloanea L. from the Cenozoic sediments of India and Asia as well. The recovery of this species and other earlier-described evergreen taxa from the same formation, suggests the existence of a tropical, warm and humid climatic conditions during the depositional period. The present study further suggests that after Pliocene the taxon might have shifted from Darjeeling Himalayan region to the adjoining southeast Asian land masses, due to possible climate change caused by post-Pliocene orogenic movement of the Himalaya.  相似文献   

Carbon dioxide,water vapour and energy fluxes over a semi-evergreen forest in Assam,Northeast India     

Dipankar Sarma  Kushal Kumar Baruah  Rulee Baruah  Nirmali Gogoi  Abhijit Bora  Supriyo Chakraborty  Anand Karipot 《Journal of Earth System Science》2018,127(7):94

The eddy covariance method is a powerful technique for quantification of \(\hbox {CO}_{2},\) \(\hbox {H}_{2}\)O and energy fluxes in natural ecosystems. Leaf area index (LAI) and its changes are significant drivers of \(\hbox {CO}_{2}\) and \(\hbox {H}_{2}\)O exchange in a forest ecosystem due to their role in photosynthesis. The present study reports the seasonal variation of \(\hbox {CO}_{2}\) and energy fluxes and their relationship with other meteorological parameters of a semi-evergreen primary forest of Kaziranga National Park, Assam, India during February 2016–January 2017. The diurnal pattern of half hourly average \(\hbox {CO}_{2 }\) fluxes over the forest was found to be mostly dominated by the incident photosynthetically active radiation. During the period of study, diurnal variations of \(\hbox {CO}_{2}\) flux showed a maximum value of \(-9.97\,\upmu \)mol \(\hbox {m}^{-2}\hbox {s}^{-1}\) in the month of June during summer which is also the beginning of the monsoon season. The monthly averaged diurnal \(\hbox {CO}_{2}\) flux and variation in LAI of the forest canopy closely followed each other. The annual net ecosystem exchange of the forest estimated from the \(\hbox {CO}_{2}\) flux data above the canopy is 84.21 g C \(\hbox {m}^{-2}\,\hbox {yr}^{-1}\). Further studies are in progress to confirm these findings. The estimated average annual evapotranspiration of the semi-evergreen forest is 2.8 ± 0.19 mm \(\hbox {day}^{-1}\). The study of partitioning of energy fluxes showed the dominance of latent heat fluxes over sensible heat fluxes. The energy balance closure was found to increase with an increase in instability and the highest closure of around 83% was noted under neutral conditions.  相似文献   

Thermal history of a Late Mesoproterozoic paired metamorphic belt (?) during Rodinia assembly: New insight from medium-pressure granulites from the Aravalli-Delhi Mobile Belt,Northwestern India     

Santanu Kumar Bhowmik  Somnath Dasgupta  Sudipta Baruah  Deepika Kalita 《地学前缘(英文版)》2018,9(2):335-354

In this study, we investigate the possible record of a Late Mesoproterozoic paired metamorphic belt in the Aravalli-Delhi Mobile Belt(ADMB), NW India using a suite of supracrustal and metaigneous granulites from the Pilwa-Chinwali granulite terrain at the north-western margin of the ADMB. Using metamorphic reaction textures, mineral chemistry, metamorphic reaction history, geothermobarometric computations and electron microprobe dating of monazite in 5 samples of pelitic granulite, leptynite gneiss, enderbite and charnockite, we have deduced a medium-pressure granulite facies metamorphism(P between 4.9 and 6.8 kbar, T 760-815℃) along a heating-cooling, counterclockwise P-T path between 1.09 and 1.01 Ga. When collated with published metamorphic and chronological constraints and geological settings of the adjoining crustal domains of the ADMB, these findings provide new insights into the developments of two tectonic domains of contrasting thermal gradients at ca. 1.0 Ga, consistent with metamorphic transformations in tectonically thickened middle-lower crustal sections during continental collision to continental subduction and in the root zones of spatially adjacent island arc, as part of the Rodinia supercontinent assembly event.  相似文献