Orbital X-ray modulation study of three supergiant HMXBs     

Chetana Jain  Biswajit Paul  Anjan Dutta 《中国天文和天体物理学报》2009,9(12)

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Relative performance of focused and unfocused devices in a two-dimensional borehole environment     

K.K. Roy  D.J. Dutta 《Journal of Applied Geophysics》1997,36(4):181-194

Borehole direct current (dc) resistivity problems are solved using finite difference method (FDM) primarily to extend the log interpretation in the two-dimensional (2D) domain. Transitional invaded zone, flushed zone, uncontaminated zone, shoulder beds and borehole filled with mud are simulated simultaneously in the model. Linear variation of resistivity is assumed for transitional invaded zone. Normal, lateral and modified laterolog7 (LL7⁴) electrode configuration (discussed in the text) responses were computed using expanding rectangular grid system. LL7⁴ responses with variable geometric factor did show some superiority over the conventional normal and lateral for conductive target beds sandwiched between the resistive beds. For relatively small borehole diameter, all three probes can detect resistive target bed satisfactorily. However, for highly conductive mud both LL7⁴ and normal electrode configuration fail to detect any signal from the target bed. Bypassing effect of the current for LL7⁴ is more than that in normal log. Lateral log shows a signal of conductive invaded zone generated by the conductive mud. Bucking current ratio peaks and the geometric factor peaks in LL7⁴ can detect the bed boundaries.  相似文献   

Region-specific deterministic and probabilistic seismic hazard analysis of Kanpur city     

Anbazhagan P  Ketan Bajaj  Nairwita Dutta  Sayed S R Moustafa  Nassir S N Al-Arifi 《Journal of Earth System Science》2017,126(1):12

A seismic hazard map of Kanpur city has been developed considering the region-specific seismotectonic parameters within a 500-km radius by deterministic and probabilistic approaches. The maximum probable earthquake magnitude (M _max) for each seismic source has been estimated by considering the regional rupture characteristics method and has been compared with the maximum magnitude observed \(\left ({M_{\max }^{\text {obs}}}\right )\), \(M_{\max }^{\text {obs}} +0.5\) and Kijko method. The best suitable ground motion prediction equations (GMPE) were selected from 27 applicable GMPEs based on the ‘efficacy test’. Furthermore, different weight factors were assigned to different M _max values and the selected GMPE to calculate the final hazard value. Peak ground acceleration and spectral acceleration at 0.2 and 1 s were estimated and mapped for worst-case scenario and 2 and 10% probability of exceedance for 50 years. Peak ground acceleration (PGA) showed a variation from 0.04 to 0.36 g for DSHA, from 0.02 to 0.32 g and 0.092 to 0.1525 g for 2 and 10% probability in 50 years, respectively. A normalised site-specific design spectrum has been developed considering three vulnerable sources based on deaggregation at the city center and the results are compared with the recent 2011 Sikkim and 2015 Nepal earthquakes, and the Indian seismic code IS 1893.  相似文献   

Rayleigh wave propagation in a two-layer anisotropic media     

Subhas Dutta 《Pure and Applied Geophysics》1965,60(1):51-60

Summary The possibility of propagation of Rayleigh waves in an incompressible crust of constant density and rigidity varying exponentially with depth lying on a semi-infinite transversely isotropic base has been discussed in this paper. Frequency equation has been derived and numerical calculations are made. The result obtained in this case is compared with that ofNewlands [3]²) andDutta [4].  相似文献   

Integrated studies for characterization of lineaments used to locate groundwater potential zones in a hard rock region of Karnataka, India     

Subash Chandra  V. A. Rao  N. S. Krishnamurthy  S. Dutta  Shakeel Ahmed 《Hydrogeology Journal》2006,14(6):1042-1051

An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.The online version of the original article can be found at  相似文献   

Chuaria circularis from the early Mesoproterozoic Suket Shale, Vindhyan Supergroup, India: Insights from light and electron microscopy and pyrolysis-gas chromatography     

Suryendu Dutta  Michael Steiner  Santanu Banerjee  Bernd-Dietrich Erdtmann  Silambuchelvan Jeevankumar  Ulrich Mann 《Journal of Earth System Science》2006,115(1):99-112

Chuaria circularis (Walcott 1899) from the Suket Shale of the Vindhyan Supergroup (central India) has been reinvestigated for its morphology and chemical composition using biostatistics, electron microscopy and pyrolysis-gas chromatography. Morphology and microscopic investigations provide little clues on the specific biological affinity ofChuaria as numerous preservational artifacts seem to be incorporated. On the contrary, the predominance of η aliphatic pyrolysates of presently studiedChuaria from India rather supports an algal affinity. Moreover, the reflectance ofC circularis can be used to obtain a comparative maturity parameter of the Precambrian sediments. The review of the age and geographical distribution ofC circularis constrains that this species cannot be considered as an index fossil for the Proterozoic time.  相似文献   

Disease detection in mustard crop using eo-1 hyperion satellite data     

S. Dutta  B. K. Bhattacharya  D. R. Rajak  C. Chattopadhayay  N. K. Patel  J. S. Parihar 《Journal of the Indian Society of Remote Sensing》2006,34(3):325-330

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Phycoremediation of cyanide from coke–oven wastewater using cyanobacterial consortium     

S. Sen  K. Bhardwaj  S. Guha Thakurta  J. Chakrabarty  K. C. Ghanta  S. Dutta 《International Journal of Environmental Science and Technology》2018,15(10):2151-2164

Owing to the presence of several toxic pollutants such as cyanide, phenol, ammonium, coke–oven wastewater is being considered as hazardous stream and needs to be treated properly. In the present study, cyanobacterial consortium of Dinophysis acuminata and Dinophysis caudata, collected from East Kolkata Wetland, was used for the treatment of both synthetic cyanide solution and real coke–oven wastewater. The growth kinetics was studied considering nitrate as substrate. Since consortium showed growth in cyanide solution, a model was proposed considering both nitrate and cyanide as substrates. The simulated data match quite well with experimental ones. Two coke–oven wastewater samples were collected—untreated one from equalization tank and another from secondary clarifier effluent and treated with consortium separately. Lipid was extracted from biomass of native cyanobacterial consortium, biomass treated with raw coke–oven wastewater and biomass treated with secondary clarifier effluents. Fatty acid methyl ester of such lipid samples was analyzed using gas chromatograph.  相似文献   

Ductile Shear Zones: From Micro‐ to Macro‐scales. Edited by: Soumyajit Mukherjee and Kieran. F. Mulchrone. Wiley‐Blackwell,Chichester, 2016. No. of pages: xii + 306. Price: US$175.00. ISBN: 978‐1‐118‐84496‐0 (hardcover).     

Dripta Dutta 《Geological Journal》2016,51(3):504-504

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Evaluating Environmental Sensitivity of Arid and Semiarid Regions in Northeastern Rajasthan,India          下载免费PDF全文

Srimoyee Dutta  Gargi Chaudhuri 《Geographical review》2015,105(4):441-461

Arid regions of Rajasthan in India are characterized by harsh environments, fragile ecosystems, and limited water resources and arable lands. Desertification is one of the major land‐degradation problems in these regions. Recent changes in the regional climatic regime and the low availability of water in this northwestern state of India, pose the threat of desertification in the agriculturally productive part of the state. This study aims to delineate the environmentally sensitive areas to desertification in the districts of Jhunjhunun and Sikar in Rajasthan, India. It uses geospatial data from various sources, and combines them to calculate an environmental sensitivity index (ESI), which will allow the quantification of the area's vulnerability to desertification. The study uses the analytical hierarchical process (AHP) to assign respective weights to individual factors for each index calculation. Land‐cover maps and socio‐economic data have been used to understand their relationship with ESI. Results showed that 13 percent and 45 percent of the study area are under highly sensitive and moderately sensitive zones, respectively. Mapping and monitoring of environmentally sensitive areas in such arid regions are critical to sustainable use and planning of natural resources namely water and land‐cover and are helpful in determining priority actions and their successful implementation.  相似文献