排序方式: 共有27条查询结果,搜索用时 31 毫秒
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Sudip Dey Sushmita Paul Chandrani Debbarma Prasamita Sarkar 《Journal of the Geological Society of India》2011,77(4):367-376
The present work concentrates on microstructure imaging for visualising the changes of depositional environment during Tertiary
period. For that purpose Tipam layers of Gajalia fold area in southern Tripura was selected which was deposited during late
Tertiary period under marine-coastal environment. Thin sections of eleven selected samples of the study area were prepared
in the laboratory for microstructure analysis. For visualising the crystalline particles or quartz brightness and contrast
of the image was increased up to maximum level. Surface conditions of the samples were analysed within RGB combination. The
grain size and shapes of the eleven samples tested prove that the depositional environment remained very dynamic through Tertiary
period in the study area. The microstructure and surface conditions also strongly support this view. 相似文献
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Sudip Bhattacharyya 《中国天文和天体物理学报》2010,10(3)
We report an indication(3.22 σ)of ≈ 1860Hz quasi-periodic oscillations from a neutron star low-mass X-ray binary 4U 1636-536.If confirmed,this will be by far the highest frequency feature observed from an accreting neutron star system,and hence could be very useful in understanding such systems.This plausible timing feature was observed simultaneously with lower(≈ 585Hz)and upper(≈ 904Hz)kilohertz quasi-periodic oscillations.The two kilohertz quasi-periodic oscillation frequencies had a ratio of ≈ 1.5,and t... 相似文献
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In recent decades, there have been discussions and predictions regarding the impact of climate on floods, due to its socioeconomic and environmental consequences. For accurate prediction of future flood events and their impacts, it is crucial to have an improved understanding on past flood events. Lacustrine sediments have been used as a natural archive to study the past flood events. Here, we study the impact of 1954 flood event on the lacustrine environment of Bengas and Rupa Lake in central Nepal based on X-ray fluorescence spectrometry (XRF) element analysis, magnetic susceptibility (MS), total organic carbon (TOC) and the biomarker molecular compositions. Results showed that 1954 flood event had significant impacts on the two lakes in terms of detrital input, organic matter deposition and aquatic production. Before the flood event, both two studied lakes had relatively lower catchment erosion rate, lower organic matter deposition and aquatic production. During the flood event, catchment erosion and aquatic production increased in both lakes due to mass transport deposits and the increased nutrition loading attributed to flood event. Following the flood event, Begnas Lake showed the sharp increase in organic matter deposition, whereas in the Rupa Lake organic matter deposition showed minor changes. The difference in organic matter deposition in lakes during flooding event is likely due to detrital material brought and deposited by the flood activity. Overall our results suggest that lacustrine sediments are sensitive to the extreme event and would be an ideal archive for the reconstruction of flood events. 相似文献
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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
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General relativistic spectra of accretion discs around rapidly rotating neutron stars: effect of light bending 总被引:1,自引:0,他引:1
Sudip Bhattacharyya Dipankar Bhattacharya Arun V. Thampan 《Monthly notices of the Royal Astronomical Society》2001,325(3):989-994
We present computed spectra, as seen by a distant observer, from the accretion disc around a rapidly rotating neutron star. Our calculations are carried out in a fully general relativistic framework, with an exact treatment of rotation. We take into account the Doppler shift, gravitational redshift and light-bending effects in order to compute the observed spectrum. We find that light bending significantly modifies the high-energy part of the spectrum. Computed spectra for slowly rotating neutron stars are also presented. These results would be important for modelling the observed X-ray spectra of low-mass X-ray binaries containing fast-spinning neutron stars. 相似文献
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Sanhita Majumdar Pijush Kanti Mandal Sudip Kumar Das Rabindranath Majumdar 《洁净——土壤、空气、水》2013,41(3):291-297
Carbon bearing materials derived from rice husk (RH) have long been recognized as sorbents for diverse chemicals – both organic and inorganic. This work presents an overview of studies demonstrating a single step process of carbonization of chemically pretreated RH to produce metal impregnated silica‐carbon char designated as silicarbon materials that can be utilized in sorbing out water‐borne organic and inorganic hazardous substances (such as phenol, hexavalent chromium, fluoride, and arsenic) and air‐borne volatile organic chemicals (such as acetone, chloroform, benzene, and pyridine). The metal‐impregnated silicarbon solids derived from RH appear to constitute renewable, low‐cost, user‐friendly, and efficient materials for control systems for indoor air contamination and for industrial as well as non‐industrial hazardous aqueous pollution. 相似文献
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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
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Debasish Sarkar Sudip Kumar Das Paramartha Mukherjee Amitava Bandyopadhyay 《洁净——土壤、空气、水》2010,38(8):764-770
Experiments have been carried out to characterize the adsorption of chromium(VI) in the aqueous phase onto dried roots of water hyacinth. Results revealed a very high degree of removal efficiency (∼100%). Theoretical analyzes are also made for describing the sorption and diffusion processes. The effective pore diffusivity of chromium(VI) in the water hyacinth roots is determined by a suitable global optimization technique. The depth of penetration, on the other hand, has been estimated for various initial concentrations of chromium(VI). Theoretically predicted concentration profiles are in excellent agreement with the experimental values. 相似文献