LIVE-BED SCOUR IN LONG CONTRACTIONS   总被引：1，自引：0，他引：1  

Subhasish DEY Rajkumar V. RAIKAR 《国际泥沙研究》2006,21(2):166-170

1 INTRODUCTION Scour within a channel contraction occurs where the waterway is restricted by the foundations or road approach embankments of a bridge. Alternately, contraction scour takes place when a bridge is located at a natural contraction in the rive…  相似文献   

Spatio-temporal variations in the estimation of PM10 from MODIS-derived aerosol optical depth for the urban areas in the Central Indo-Gangetic Plain     

Shikha Chitranshi  Satya Prakash Sharma  Sagnik Dey 《Meteorology and Atmospheric Physics》2015,127(1):107-121

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Impacts of aerosols on dynamics of Indian summer monsoon using a regional climate model   总被引：1，自引：0，他引：1  

Sushant Das  Sagnik Dey  S. K. Dash 《Climate Dynamics》2015,44(5-6):1685-1697

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Evaluation of Recharge and Groundwater Dynamics of a Shallow Alluvial Aquifer in Central Ganga Basin,Kanpur (India)   总被引：2，自引：0，他引：2  

Anirban Dhar  Satiprasad Sahoo  Saumava Dey  Madhumita Sahoo 《Natural Resources Research》2014,23(4):409-422

Evaluation of recharge and groundwater dynamics of an aquifer is an important step for finding a proper groundwater management scenario. This has been performed on the basis of statistical Kendall Tau test to find a relationship between groundwater levels and hydro-meteorological parameters (e.g., precipitation, temperature, evaporation). Recharge to the aquifer was estimated for identification of critical areas/locations based on the analytical Soil and Water Assessment Tool. Moreover, spatiotemporal variability of groundwater levels has been quantified using space–time variogram. The overall characterization method has been applied to the shallow alluvial aquifer of Kanpur city in India. The analysis was performed using groundwater level data from 56 monitoring piezometer locations in Kanpur from March 2006 to June 2011. Groundwater level shows relatively higher correlation with temperature. Performance of the geostatistical model was evaluated by comparing with the observed values of groundwater level from January 2011 to June 2011 for two scenarios: “with limited spatiotemporal data” and “without spatiotemporal data.” It is evident that spatiotemporal prediction of groundwater level can be performed even for the unmonitored/missing data. This analysis demonstrates the potential applicability of the method for a general aquifer system.  相似文献   

Experiment on visualizing micro-level surface characters of sediment sections: a methodological approach to reflectance-based alternative petrographic image analysis   总被引：1，自引：1，他引：0  

Sudip Dey  Chandrani Debbarma  Prasamita Sarkar  Muh Aris Marfai 《Arabian Journal of Geosciences》2011,4(5-6):899-906

This paper discusses an experiment on digital imaging and visualizing the surface condition of the sediment depositions. For that purpose, a part of South Tripura district was selected as sampling site. Physically, the selected area is located in a fold belt and preserves the history of Tertiary–Quaternary landform evolution in the main types of sediment depositions. Three samples, each from the different types of Tertiary depositions, were finally taken for thick section making, optical microscopy under reflected light, and soft computing. Geometric optical measurement and physical optical measurement were done to understand the surface condition of Bokabil, Tipam, and Duplitila samples by bidirectional reflectance distribution function and radiometric scales (within 0–255 digital number values). Maximum surface smoothness or near-perfect reflection surface was measured by brightness–contrast slicing operation.  相似文献   

HST Imaging of an Old Galaxy Group at Z=1.55     

Andrew J. Bunker  Hyron Spinrad  Ross McLure  Arjun Dey  James Dunlop  John Peacock  Daniel Stern  Rodger Thompson  Ian Waddington  Rogier Windhorst 《Astrophysics and Space Science》2002,281(1-2):527-528

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Old elliptical galaxies at  z ≃ 1.5  and the Kormendy relation     

I. Waddington  R. A. Windhorst  S. H. Cohen  J. S. Dunlop  J. A. Peacock  R. Jimenez  R. J. McLure  A. J. Bunker  H. Spinrad  A. Dey  D. Stern 《Monthly notices of the Royal Astronomical Society》2002,336(4):1342-1350

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Early Neoarchaean A-type granitic magmatism by crustal reworking in Singhbhum craton: Evidence from Pala Lahara area,Orissa     

Abhishek Topno  Sukanta Dey  Yongsheng Liu  Keqing Zong 《Journal of Earth System Science》2018,127(3):43

Several volumetrically minor \(\sim \)2.8 Ga anorogenic granites and rhyolites occur along the marginal part of the Singhbhum craton whose origin and role in crustal evolution are poorly constrained. This contribution presents petrographic, geochemical, zircon U–Pb and trace element, and mineral chemical data on such granites exposed in the Pala Lahara area to understand their petrogenesis and tectonic setting. The Pala Lahara granites are calc-alkaline, high-silica rocks and define a zircon U–Pb age of 2.79 Ga. These granites are ferroan, weakly metaluminous, depleted in Al, Ca and Mg and rich in LILE and HFSE. They are classified as A2-type granites with high Y/Nb ratios. Geochemical characteristics (high \(\hbox {SiO}_{2}\) and \(\hbox {K}_{2}\hbox {O}\), very low MgO, Mg#, Cr, Ni and V, negative Eu anomaly, flat HREE and low Sr/Y) and comparison with melts reported by published experimental studies suggest an origin through high-temperature, shallow crustal melting of tonalitic/granodioritic source similar to the \(\sim \)3.3 Ga Singhbhum Granite. Intrusion of the Pala Lahara granites was coeval with prominent mafic magmatism in the Singhbhum craton (e.g., the Dhanjori mafic volcanic rocks and NNE–SSW trending mafic dyke swarm). It is suggested that the \(\sim \)2.8 Ga A-type granites in the Singhbhum craton mark a significant crustal reworking event attendant to mantle-derived mafic magmatism in an extensional tectonic setting.  相似文献   

Seismic assessment in southern Baromura hill,northeast India,considering geophysical aspects     

Sudip Dey  Prasamita Sarkar  Chandrani Debbarma  Sushmita Paul 《Environmental Earth Sciences》2012,66(2):421-431

This paper aims to assess the geophysical signatures like morphology and structure of a fault line, which is situated in a part of southern Baromura hill of Tripura, northeast India. In this work manual observations and technical applications were adopted for understanding the morphological and structural characters of the fault line. As tectonic mapping is one of the main objectives of this study, the remote sensing technique was used to prepare a tectonic map of the study area. Geothermal range of the area was measured by unsupervised classification of Landsat TM thermal infrared band (band 6). The classified thermal band was overlaid by another classified shortwave infrared band (band 7 of Landsat TM), which explains the structural evidences of the study area. In addition, an automated digital elevation model (DEM) was prepared to assess the morphological characters of the study area particularly near the confluence of R. Maharani and R. Gumti. To analyse the structural condition of the faulted zone, resistivity characters of the rocks were measured by “vertical electrical sounding” (VES) method. The electrical resistivity character of this area strongly supports that a displacement occurred in this place. Finally an attempt was made to explain the character of faulting on the basis of morphological signatures and structural evidences for future disaster management planning.  相似文献   

Turbulence in mobile-bed streams   总被引：2，自引：1，他引：1  

Subhasish Dey  Ratul Das  Roberto Gaudio  Sujit K. Bose 《Acta Geophysica》2012,60(6):1547-1588

This study is devoted to quantify the near-bed turbulence parameters in mobile-bed flows with bed-load transport. A reduction in near-bed velocity fluctuations due to the decrease of flow velocity relative to particle velocity of the transporting particles results in an excessive near-bed damping in Reynolds shear stress (RSS) distributions. The bed particles are associated with the momentum provided from the flow to maintain their motion overcoming the bed resistance. It leads to a reduction in RSS magnitude over the entire flow depth. In the logarithmic law, the von Kármán coefficient decreases in presence of bed-load transport. The turbulent kinetic energy budget reveals that for the bed-load transport, the pressure energy diffusion rate near the bed changes sharply to a negative magnitude, implying a gain in turbulence production. According to the quadrant analysis, sweep events in mobile-bed flows are the principal mechanism of bed-load transport. The universal probability density functions for turbulence parameters given by Bose and Dey have been successfully applied in mobile-bed flows.  相似文献