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101.
102.
Dipak Sarkar S. K. Gangopadhyay A. K. Sahoo 《Journal of the Indian Society of Remote Sensing》2006,34(3):245-260
Visual interpretation of IRS ID LISS-III fused with PAN data (1:12,500 scale) ofPatloinala micro-watershed of Puruliya district, West Bengal was carried out for delineating the physiographic units based on the variations
in image characteristics. The major physiographic units identified were upland(Tanr), medium land(Baid), and low land(Bahal andKanali). The satellite remote sensing data coupled with ground truth were translated in terms of soils using composite interpretation
map as base. The abstraction level attained was phases of soil series based on Soil Taxonomy. On the basis of physiographic
variation and soil or soil site characteristics such as texture, depth, slope, erosion etc. the problem areas were identified
and land use plan has been suggested for the overall development of the micro-watershed. 相似文献
103.
Dipto Sarkar Clio Andris Colin A. Chapman Raja Sengupta 《International journal of geographical information science》2019,33(5):1017-1039
Social Network Analysis offers powerful tools to analyze the structure of relationships between a set of people. However, the addition of spatial information poses new challenges, as nodes are embedded simultaneously in network space and Euclidean space. While nearby nodes may not form social ties, ties may exist at a distance, a configuration ill-suited for traditional spatial metrics that assume adjacent objects are related. As such, there are relatively few metrics to describe these nuanced situations. We advance the burgeoning field of spatial social network analysis by introducing a set of new metrics. Specifically, we introduce the spatial social network schema, tuning parameter and the flattening ratio, each of which leverages the notion of ‘distance’ to augment insights obtained by relying on topology alone. These methods are used to answer the questions: What is the social and spatial structure of the network? Who are the key individuals at different spatial scales? We use two synthetic networks with properties mimicking the ones reported in the literature as validation datasets and a case study of employer–employee network. The methods characterize the employer–employee as spatially loose with predominantly local connections and identify key individuals responsible for keeping the network connected at different spatial scales. 相似文献
104.
The A-type Mayurbhanj Granite Pluton (3.09 Ga), occurring along the eastern margin of the Singhbhum-Orissa Craton, eastern India, represents the final phase of acid plutonism in this crustal block of Archean age. The granite shows a bimodal association with a voluminous gabbroid body, exposed mainly along its western margin, and is associated with the Singhbhum Shear zone. The granite pluton is composed mainly of a coarse ferrohastingsite–biotite granite phase, with an early fine-grained granophyric microgranitic phase and a late biotite aplogranitic phase. Petrogenetic models of partial melting, fractional crystallisation and magma mixing have been advocated for the evolution of this pluton. New data, combined with earlier information, suggest that two igneous processes were responsible for the evolution of the Mayurbhanj Granite Pluton: partial melting of the Singhbhum Granite; followed by limited amount of mixing of acid and basic magmas in an anorogenic extensional setting. The necessary heat for partial melting was provided by the voluminous basaltic magma, now represented by the gabbroid body, emplaced at a shallow crustal level and showing a bimodal association with the Mayurbhanj Granite Pluton. The Singhbhum Shear Zone provided a possible channel way for the emplacement of the basic magma during crustal extension. It is concluded that all three phases of the Mayurbhanj Granite Pluton were derived from the same parent magma, generated by batch partial melting of the Singhbhum Granite at relatively high temperatures (980 °C) and low pressures (4 to <2 kbar) under anhydrous conditions. The coarse ferrohastingsite biotite granite phase shows evidence of limited and heterogeneous assimilation of country rock metasediments. However, the early microgranite phase and late aplogranite phase have not assimilated any metasediments. Compositional irregularities observed along the western margin of the Mayurbhanj Granite Pluton in contact with the gabbro body including a continuous fractionating sequence from quartz diorite to alkali-feldspar granite in the Notopahar area. Gradational contacts between the gabbro and the Mayurbhanj Granite Pluton in the Gorumahisani area etc., may be attributed to a limited amount of mixing between the gabbroid magma and the newly generated Mayurbhanj Granite magma. The mixing was mainly of liquid–liquid diffusive type, with a subordinate amount of mixing of solid–liquid type. Although A-type granites are commonly described as having high total REE (e.g. 270–400 ppm), studies on the late aplogranite phase of the Mayurbhanj Granite show that total REE values (100 ppm) are low. This low REE abundance may be attributed to the progressive residual nature of the Singhbhum Granite source during continued partial melting, when the magmas of the microgranite and coarse granite phases had already been removed from the source region. 相似文献
105.
Abul Amir Khan Naresh Chandra Pant Anindaya Sarkar S.K. Tandon Meloth Thamban Mahalinganathan K. 《地学前缘(英文版)》2017,8(1):107-115
The cryosphere constitutes an important subset of the hydrosphere.The Himalayan cryosphere is a significant contributor to the hydrological budget of a large river system such as the Ganges.Basic data on the cryosphere in the Himalaya is inadequate and also has large uncertainties.The data on glacial melt component in the Himalayan rivers of India also shows high variability.The Gangotri glacier which constitutes nearly a fifth of the glacierized area of the Bhagirathi basin represents one of the fastest receding,large valley glaciers in the region which has been surveyed and monitored for over sixty years.The availability of measurement over a long period and relatively small glacier-fed basin for the Bhagirathi river provides suitable constraints for the measurement of the glacial melt fraction in a Himalayan river.Pre- and post-monsoon samples reveal a decreasing trend Of depletion of δ~(18)O in the river water from glacier snout(Gaumukh) to the confluence of the Bhagirathi river with the Alaknanda river near Devprayag.Calculations of existing glacial melt fraction(~ 30%at Rishikesh) are not consistent with the reported glacial thinning rates.It is contended that the choice of unsuitable end-members in the three component mixing model causes the overestimation of glacial melt component in the river discharge.Careful selection of end members provides results(~11%at Devprayag) that are consistent with the expected thinning rates. 相似文献
106.
107.
108.
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
109.
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
110.
S. S. De Manasi Mal Bithika Ghosh B. K. Sarkar B. Ghosh S. K. Adhikari 《Astrophysics and Space Science》1992,194(2):251-259
Wave equations in an anisotropic plasma imbedded in a moving dielectric medium have been derived through Maxwell-Minkowski relations. These are solved for longitudinal and transverse cases of propagation. The dispersion relation within the medium has been deduced through which the nature of splitting may be understood. 相似文献