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排序方式: 共有157条查询结果,搜索用时 78 毫秒
31.
Sitiraju Srinivasa Rao Dinesh Kumar Sahadevan Milind R. Wadodkar M/ S. S. Nagaraju Sudipta Chattaraj William Joseph Prasanth Rajankar Titu Sengupta M. V. Venugopalan Subrata N. Das Asok Kumar Joshi Jaswanth Raj Sharma Eadara Amminedu 《Journal of the Indian Society of Remote Sensing》2016,44(2):277-285
32.
This paper deals with the computation of the depth to the magnetic interface from the total magnetic field intensity values obtained along profiles in the offshore area between Vengurla and Rajapur bay off the West Coast of India, by the application of one dimensional spectral analysis method.From the response characteristics of the total field magnetic values it is surmised that the magnetic interface may be identified with the Deccan trap series of rocks which are likely to form the magnetic basement rocks in this area.The plot of depths to the basement rocks as obtained from spectral analysis indicates that the basement is sloping towards outer edge of the Continental Shelf though not uniformly. 相似文献
33.
When individuals of a species utilize an environment, they generate movement patterns at a variety of spatial and temporal scales. Field observations coupled with location technologies (e.g. GPS tags) enable the capture of detailed spatio‐temporal data regarding these movement patterns. These patterns contain information about species‐specific preferences regarding individual decision‐making, locational choices and the characteristics of the habitat in which the animal resides. Spatial Data Mining approaches can be used to extract repeated spatio‐temporal patterns and additional habitat preferences hidden within large spatially explicit movement datasets. We describe a method to determine the periodicity and directionality in movement exhibited by a migratory bird species. Results using a High Arctic‐nesting Svalbard Barnacle Goose movement data yielded undetected patterns that were secondarily corroborated with expert field knowledge. Individual revisits by the geese to specific locations in the breeding and wintering grounds of Svalbard, Norway and Solway, Scotland, occurred with a periodicity of 334 days . Further, the orientation of this movement was detected to be mostly north‐south. During long‐range migration the geese use the north‐south oriented Norwegian islands as “stepping stones”, Short‐range movement between mudbank roosts to feeding fields in Solway also retained a north‐south orientation. 相似文献
34.
Chandreyee Sengupta K. S. Dwarakanath D. J. Saikia 《Monthly notices of the Royal Astronomical Society》2009,397(1):548-557
We present the results of Giant Metrewave Radio Telescope (GMRT) observations of the interacting system Arp86 in both neutral atomic hydrogen, H i , and in radio continuum at 240 606 and 1394 MHz. In addition to H i emission from the two dominant galaxies, NGC 7752 and NGC 7753, these observations show a complex distribution of H i tails and bridges due to tidal interactions. The regions of highest column density appear related to the recent sites of intense star formation. H i column densities ∼1–1.5 × 1021 cm−2 have been detected in the tidal bridge which is bright in Spitzer image as well. We also detect H i emission from the galaxy 2MASX J23470758+2926531, which is shown to be a part of this system. We discuss the possibility that this could be a tidal dwarf galaxy. The radio continuum observations show evidence of a non-thermal bridge between NGC 7752 and NGC 7753, and a radio source in the nuclear region of NGC 7753 consistent with it having a low-ionization nuclear emission region nucleus. 相似文献
35.
By measuring the ratio of wavelength to arclength of folds in closely associated disharmonically folded competent layers,
it is possible to determine which layer has undergone a greater layer-parallel strain and has a smaller competence. This method
may lead to a paradoxical situation. For example when foliated quartzite and mica schist layers are folded together, the mica
schist laminae show a much larger buckle shortening than the quartzite layers. On the other hand, the geometry of folds in
quartzite indicates that quartzite was more competent than the mica schist. The structure can be explained by different modes
of buckling, general buckling in quartzite layers and internal buckling in strongly anisotropic mica schists. 相似文献
36.
Dr. Sudipta Sengupta 《International Journal of Earth Sciences》1977,66(1):175-192
The Singhbhum Shear Zone separates the rocks of a highly metamorphosed northern group from an unmetamorphosed southern group. It had been recognised by earlier workers as a thrust zone in which the thrust movements were achieved by slip along a pre-existing schistosity. Deformed conglomerates crop out in discontinuous bands along the Shear Zone. Strain determinations from these conglomerates have been made to ascertain the strain pattern within the Shear Zone. None of the existing methods of determining strain from stretched pebbles can be applied to these conglomerates. An approximate value for shortening perpendicular to the schistosity can however be obtained from cross-cutting buckled veins. Detailed study of various small-scale structures clearly indicates that the principal structures of this region cannot be explained simply by a slipping on the schistosity.
Zusammenfassung Die Singhbhum-Scherzone trennt die Gesteine der stark metamorphen nördlichen Gruppe von denjenigen einer nicht metamorphen südlichen Gruppe. Nach früheren Autoren ist es eine Überschiebungszone, worin die Überschiebungsbewegungen durch das Gleiten entlang einer älteren Schieferung zustande kamen. Deformierte Trümmergesteine treten in ununterbrochenen Bändern entlang der Scherzone auf. Man hat Deformationsbestimmungen von diesen Trümmergesteinen gemacht, um das Deformationsbild in der Scherzone zu erklären. Eine ausführliche Untersuchung der verschiedenen kleinmaßstäblichen Strukturen zeigt deutlich, daß die Hauptstrukturen dieser Gegend nicht einfach durch das Gleiten auf der Schieferung erklärt werden können.
Résumé La zone de cisaillement de Singhbhum sépare les roches très métamorphiques au nord, de celles d'un groupe non-métamorphique au sud. Elle avait été reconnue lors de recherches précédentes comme étant la base de charriages suivant laquelle la poussée se serait faite par glissement le long d'une schistosité pré-existante. Des conglomérats déformés affleurent par bandes discontinues le long de cette zone. Grâce à ces conglomérats, des estimations sur la déformation ont été faites pour définir le style de déformation dans la zone de glissement. Une étude détaillée de différentes structures à petite échelle indique clairement qu'on ne peut pas expliquer les principales structures de cette région uniquement par un glissement sur la schistosité.
. , , . . , . , .相似文献
37.
38.
Summary A one dimensional problem concerning the wave propagation in a non-homogeneous conical rod having its cross-section directly proportional to the square of the distance from a chosen point is considered in this paper. One end of the rod is subjected to a pressure step while the other end is stress free and the pulse shape is examined when the propagation speed of the wave has a particular continuous distribution over the entire rod. 相似文献
39.
Basab Mukhopadhyay P. K. Mukherjee Debkumar Bhattacharya S. Sengupta 《Environmental Geology》2006,49(7):1009-1020
Groundwater extracted from shallow aquifers in the Bengal Delta is contaminated with arsenic. The fluviodeltaic process that
creates aquifers, ironically, extends its role to also contaminating them with arsenic. The arsenic distribution maps show
a spatial association of arsenic-contaminated wells with palaeo/cut-off/abandoned channels. Weight-on-evidences analysis indicates
that the zones of contamination occur around palaeo-channels within a corridor of 500–700 m that contains most of the contaminated
wells. These corridors are interpreted to be the zone of channel shifting. Contaminated wells represent point fractal geometry
that can be separated into isolated points and clusters. Clusters occur within the zone of channel shifting as obtained by
weight-on-evidences analysis. Isolated points occur within floodplain or back swamp areas. Clusters and isolated point fractals
are interpreted to reflect the process of arsenic release into groundwater. The migration of biomass within the permeable
sandy domain of channel deposits is proposed to be the predominant process in generating clusters. The isolated points represent
restricted biomass spreading in less permeable clay-silt dominated floodplains. 相似文献
40.
An assessment of soil contamination due to heavy metals around a coal-fired thermal power plant in India 总被引:3,自引:0,他引:3
Combustion of coals in thermal power plants is one of the major sources of environmental pollution due to generation of huge amounts of ashes, which are disposed off in large ponds in the vicinity of the thermal power plants. This problem is of particular significance in India, which utilizes coals of very high ash content (∼55 wt%). Since the thermal power plants and the ash ponds are located in densely populated areas, there is potential chance for contamination of soil and groundwater of the surrounding areas from the toxic trace elements in the ash. An attempt has been made to study the extent of soil contamination around one of the largest thermal power plants of India located at Kolaghat, West Bengal India. Chemical analysis of the top soils and the soils collected from the different depth profiles surrounding the ash ponds, show that the top soils are enriched in the trace elements Mo, As, Cr, Mn, Cu, Ni, Co, Pb, Be, V, Zn, which show maximum enrichment (2–5) in the top soils collected from all the soil profiles. These elements are also enriched in the pond ash. Since there are no other sources of industrial effluents, it can be said that the enrichment of the trace elements (Mn, Co, Mo, Cr, Cu, Pb, Zn, As, Ni, Be, V) is attributed to their input from ash from the disposal pond. The study has been further strengthened by log-normal distribution pattern of the elements. 相似文献