http://www.sciencedirect.com/science/article/pii/S1674987113000340     

Suman Kilaru  Bandaru Karunakar  Goud Vijay  Kumar Rao 《地学前缘(英文版)》2013,4(6):717-728

Regional surface gravity data and global satellite magnetic data have been utilized to generate a preliminary model of the crustal structure along a southwest-northeast profile （Gadra-Fatehpur） through western Rajasthan.The study area represents the western part of the Indian continental landmass which has undergone several major episodes of repeated subduction/collision,plume traces and rifting from Archaean to recent times.The temporal and spatial relationship between the various geotectonic provinces is quite complex,thereby limiting the emergence of a suitable crustal structure model for this region.Exposures of the Malani Igneous Suite （MIS）,a product of bimodal volcanism （～780 Ma）,and considered to be the third largest felsic magmatic province of the world,is evident along the profile and also to the southwest of the study area.The easternmost part of the profile is close to the DAFB （Delhi Aravalli Fold Belt）,a Proterozoic orogenic belt.This study probes the geometry of the different crustal units in terms of density and susceptibility variations in order to decipher the imprints of the major tectonic processes the region has undergone.In order to decipher the crustal geometry of the Gadra-Fatehpur profile,two NW-SE gravity and magnetic profile vertical sections （A-A＇ in the south and B-B＇ in the north） are modelled on the basis of the constraints provided from previous seismic models.The crustal model of the Gadra-Fatehpur profile is composed of alluvium,Tertiary sediments,MIS,Marwar Supergroup,low-density layers （LDLs） and the middle-lower crustal layers,with a distinct change in configuration from the southwest to northeast.The Moho dips from SW to NE,the MIS in the SW gives way to the thick pile of the Marwar Supergroup to the NE.The evolution of MIS has been suggested to have occurred as a consequence of delamination of the upper mantle.LDLs are incorporated in Gadra-Fatehpur model.In the SW,LDL （2550 kg/m3） lies below the MIS in the NE,another LDL （2604 kg/m3） is depicted below the mid-crustal layer.  相似文献   

Point Discharge Current During a Solar Eclipse     

S. S. De  Suman Paul  S. Barui  P. Hazra  D. Kala  D. K. Haldar  A. Ghosh  G. Guha 《Earth, Moon, and Planets》2013,111(1-2):79-87

The effect of solar eclipse of July 22, 2009, obscuring up to 91 %, upon the value of point discharge current (PDC) has been reported in this paper. The observation had been taken from Kolkata (Lat. 22.56°N, Long. 88.5°E). During the eclipse period, significant variations in the magnitude of PDC were observed than their average value for the same period in other days. The average value of the PDC for the successive ±10 days adjacent to the solar eclipse day was about 2.253 A.U. (Arbitrary Unit), while the minimum value showed about 2.242 A.U. at the time of greatest phase at 06:26.4 IST (Indian Standard Time). The results are mainly interpreted in terms of changes of the conductivity of the medium during the solar eclipse.  相似文献   

Detection of 2009 Leonid,Perseid and Geminid Meteor Showers through its effects on Transmitted VLF Signals     

S. S. De  B. K. De  Pinaki Pal  B. Bandyopadhyay  S. Barui  D. K. Haldar  Suman Paul  Minu Sanfui  Goutami Chattopadhyay 《Astrophysics and Space Science》2011,332(2):353-357

The detection of 2009 Leonid, Perseid and Geminid meteor showers over Agartala, Tripura, India (Lat: 23.0° N, Long: 91.4° E) will be reported here by using two VLF receivers tuned to subionospheric transmitted VLF signals at the frequency 16.4 kHz from Aldra Island, Norway (Lat: 66.42° N, Long: 13.13° E) and the other at 18.2 kHz from Vijayananarayanam, India (Lat: 8.4° N; Long: 77.7° E). The received signals exhibited their peak values on November 17, 2009 when ZHR (Zenithal Hourly Rate) was highest. Some typical variations which are observed in the records of amplitude during the 2009 Leonid, Perseid and Geminid meteor showers will be presented in this paper.  相似文献   

Studies on the Effects of 2009 Leonid Meteor Shower on Subionospheric Transmitted VLF Signals and Vertical Electric Potential Gradient     

S. S. De  B. Bandyopadhyay  S. Barui  Suman Paul  D. K. Haldar  D. De  B. K. De  S. Chattopadhyay  A. K. Kundu 《Earth, Moon, and Planets》2012,108(2):111-121

The effects of 2009 Leonid Meteor Shower upon the two VLF subionospheric transmitted signals and vertical electric potential gradient from the ground surface have been studied from Kolkata (Lat: 22.56°N, Long: 88.5°E) on November 17, 2009. The received signals showed their peak values when ZHR (Zenithal Hourly Rate) was highest. Some typical variations in the outcome of these measurements during the meteor showers will be presented in this paper.  相似文献   

Comparative assessment of crisp and fuzzy analytic hierarchy process for multi-criteria decision making in geographic information system (GIS)-based site suitability analysis for relocation of tigers     

Laxmikant Sharma  Suman Sinha  Mahendra Singh Nathawat 《国际地球制图》2013,28(2)

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Post-seismic deformation associated with the 2001 Bhuj earthquake     

Pallabee Choudhury  J. K. Catherine  V. K. Gahalaut  Sumer Chopra  Rakesh Dumka  Ketan Singha Roy 《Natural Hazards》2013,65(2):1109-1118

We report the results of GPS measurements of post-seismic deformation due to the 2001 Bhuj earthquake in the Kachchh region, western India. The estimated horizontal velocity vectors in ITRF05 are in the range of 48?C49?mm/year in N46?C50°E. The observed velocity at the Gandhinagar permanent site, a far off site from the earthquake source region and probably unaffected by the post-seismic deformation, is 49?±?1?mm/year in N47°E, which is consistent with the predicted motion of Indian plate at Gandhinagar. At other sites in the source region, transient post-seismic deformation is found to be low; it attenuated rapidly within 3?C4?years of the earthquake and is much low now. Our results support the idea that mantle rheology is weak in the region.  相似文献   

Microfacies analysis of larger benthic foraminifera-dominated Middle Eocene carbonates: a palaeoenvironmental case study from Meghalaya,N-E India (Eastern Tethys)     

Suman Sarkar 《Arabian Journal of Geosciences》2017,10(5):121

Larger benthic foraminifera (LBF) show significant abundance and diversity in the Palaeogene carbonate sediments of Meghalaya, N-E India, but have previously received less attention from the palaeoenvironmental perspective. LBF are important contributors to recent as well as fossil shallow marine, tropical carbonate settings. They find wide application in biostratigraphy and palaeoenvironmental reconstructions. The larger foraminiferal turnover (LFT) during the Palaeocene-Eocene transition is very important with respect to their evolution in several parts of the world including the Eastern Tethys. The present microfacies analysis documents the status of LBF in the Middle Eocene sediments from the Prang Formation of the Sylhet Limestone Group in Meghalaya, N-E India. Five major facies types (MFTs)—miliolid grainstone-packstones, alveolinid-rotaliid grainstone-packstones, nummulitid-alveolinid grainstone-packstones, coralline algal-nummulitid packstone-wackestones and coralline algal wackestones have been recorded in the current study. Evaluation of the palaeoenvironmental parameters aids in understanding the seascape of this Eastern Tethyan domain. It is suggested that an oligotrophic nutrient regime supported the rapid evolution and dominance of the LBF. Most notable is the prolific augmentation in Alveolina and Nummulites populations. High surface water temperatures during the Late Palaeocene-Early Eocene global warming episode possibly persisted to a certain level during the Middle Eocene and continued to favour the larger foraminifera as the major carbonate producers instead of the vulnerable corals.  相似文献   

Flow past a circular cylinder between parallel walls at low Reynolds numbers     

Sintu Singha  K.P. Sinhamahapatra 《Ocean Engineering》2010,37(8-9):757-769

The flow about a circular cylinder placed centrally inside a channel is studied numerically with an unstructured collocated grid finite volume method based on the primitive variable formulation. The distance between the channel walls is allowed to vary to change the blockage ratio. Simulations are carried out over a range of Reynolds numbers that are consistent with the two-dimensional assumption. The study confirms that transition to vortex shedding regime is delayed when the channel walls are close to the cylinder because of the interaction between the vortices from the channel wall and cylinder wake. In the unsteady vortex shedding regime, the wake pattern is opposite to the classic Karman street in respect of the positions of the shed vortices. The cylinder drag coefficient and Strouhal number are considerably increased at smaller gaps while the root-mean-squared lift coefficient is significantly decreased. Several important flow parameters are correlated with the input parameters, namely Reynolds number and blockage ratio.  相似文献   

Information content in astronomical images     

Suman Gupta  S. P. S. Virdi 《Astrophysics and Space Science》1989,161(1):159-161

We should like to point out that the special non-singular Bianchi type-I solution of no-scale supergravity, recently obtained by Barrow and Deruelle (1988), does not exist. The most general consistent non-singular Bianchi type-I solution has been derived recently by us (Lorenz-Petzold, 1988).  相似文献   

Validation of a satellite-based cyclogenesis technique over the North Indian Ocean     

Suman Goyal  M Mohapatra  Ashish Kumar  S K Dube  Kushagra Rajendra  P Goswami 《Journal of Earth System Science》2016,125(7):1353-1363

Indian region is severely affected by the tropical cyclones (TCs) due to the long coast line of about 7500 km. Hence, whenever any low level circulation (LLC) forms over the Indian Seas, the prediction of its intensification into a TC is very essential for the management of TC disaster. Satellite Application Centre (SAC) of Indian Space Research Organization (ISRO), Ahmedabad, has developed a technique to predict TCs based on scatterometer-derived winds from the polar orbiting satellite, QuikSCAT and Oceansat-II. The India Meteorological Department (IMD) has acquired the technique and verified it for the years 2010–2013 for operational use. The model is based on the concept of analogs of the sea surface wind distribution at the stage of LLC or vortex (T1.0) as per Dvorak’s classifications, which eventually leads to cyclogenesis (T2.5). The results indicate that the developed model could predict cyclogenesis with a probability of detection of 61% and critical success index of 0.29. However, it shows high over-prediction of the model is better over the Bay of Bengal than over Arabian Sea and during post-monsoon season (September–December) than in pre-monsoon season (March–June).  相似文献