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Sahoo Monica Kumar Abhishek Chalavadi Ganesh Gupta Ambesh Singh Ranjeet K. 《Natural Resources Research》2021,30(5):3643-3658
Natural Resources Research - This study investigated the segregation of organic (maceral) and inorganic (mineral matter or ash) contents of coal in an air stratifier after design modification in... 相似文献
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We have studied the Mukundpura CM2 meteorite for magnetic properties as a function of temperature and magnetic field, as well as its Mössbauer spectrum, at room and low temperatures (up to 5 K). We find that the high temperature paramagnetic phase is followed by two magnetic transitions: a weak transition near 125 K and a strong transition at 8 K. The weak (125 K) magnetic phase can be attributed to complex Fe2+–Fe3+ constituents present in the meteorite. The absence of the characteristic sextet corresponding to magnetite in Mossbauer spectrum indicates that this magnetic phase is not magnetite, which, if present, must be in insignificant amount. The 8 K magnetic ordering is superimposed with weak ferromagnetic ordering, showing spin‐glass transition. The Mössbauer spectrum taken at 5 K substantiates the observed spin‐glassy nature, as very large hyperfine field ~32 T is recorded, causing localized subordering leading to spin‐glass behavior. The Mössbauer spectra also confirm that iron is mainly present in serpentine‐group minerals, both in ferrous and ferric states. The complete serpentinization of basic silicates indicates aggressive hydrous alteration. These results show that the observed spin‐glass signature is a characteristic feature of the cronstedtite phase in CM meteorites. This feature is unique to carbonaceous CM chondrites and could be used for nondestructive, quick, and independent classification of this rare class of meteorites. Furthermore, the absence of olivine and the presence of cronstedtite in Mossbauer spectra show that the degree of aqueous alteration observed is the most severe in Mukundpura CM2 meteorite, as compared to many other CM2 meteorites. The degree of aqueous alteration in CM2 carbonaceous chondrites increases in the sequence: Paris, Murchison, Murray, Mighei, Nogoya, Cold Bokkeveld, and Mukundpura. 相似文献
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K. H. V. Durga Rao Ambesh Kumar Singh P. S. Roy 《Journal of the Indian Society of Remote Sensing》2009,37(3):433-441
The scope of this research was to study lake morphology using spatial simulation technique, to develop revised elevation-capacity
curve, to develop elevation-water spread area curve, to study the relation between suspended sediment and remote sensing satellite
data, and to estimate suspended sediment load in the lake using a Geographic Information System coupled with ground truth.
The study area was the Bhopal Upper Lake, which has been classified as one of the major wetlands in India by the Ministry
of Water Resources, India. A precise digital elevation model was created using 0.5 meter interval contour information collected
from bathometric surveys. Water-spread areas at different water levels were simulated spatially in a Geographic Information
System (GIS) through the neighbourhood connectivity operator. Revised elevation-capacity curve and elevation-area curve of
the lake were prepared using the simulated results. Simulated water spread area at full tank level (FTL) was compared with
the actual water spread area delineated using remote sensing data. Water samples at different locations of the lake were collected
and located using the Global Positioning System (GPS) instrument. These samples were analysed in the laboratory for suspended
sediment concentration. Different image processing techniques were applied to LANDSAT 5 TM satellite digital data (except
thermal band). Correlation between radiance values of band 2 and suspended sediments was established and a positive linear
equation was found to fit the data best. Spatial distribution of suspended sediment load was estimated using the developed
regression equation and band 2 radiance image of the complete lake. Total suspended sediment load and loss of capacity at
full tank level were computed. 相似文献
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