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51.
R. Nagendra Satish J. Patel Rakesh Deepankar A. N. Reddy 《Journal of the Geological Society of India》2010,76(5):525-532
Well preserved ichnofossils were found in Kulakkalnattam sandstone exposed at Kulakkalnattam stream in Ariyalur area, Cauvery Basin. It consists of infaunal structures of both suspension and deposit feeders. Five ichnofossils are present in a fine to coarse grain sandstone which includes Ophiomorpha, Palaeophycus, Planolites Skolithos, and Thalassinoides. The study infers that ichnofossils Skolithos and Ophiomorpha are infaunal colonization of the suspension feeders in high energy condition in shifting substrate, whereas Thalassinoides and Planolites-Palaeophycus ichnofossils indicate infaunal deposit feeders living at the sediment-sediment interface in low to moderate energy conditions. Furthermore, the abundance and diversity of the trace fossils indicates there was alternatively fluctuations in energy conditions which lead to development of Skolithos and Cruziana ichnofacies type condition during the deposition of Kulkkallanattam sandstone in foreshore-shoreface environments. 相似文献
52.
Stefanie Wachter Chryssa Kouveliotou Sandeep Patel Don Figer Peter Woods 《Astrophysics and Space Science》2007,308(1-4):67-71
Both Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) are thought to be manifestations of magnetars. However, the specific physical characteristics that differentiate the two classes of objects remain unclear. There is some evidence that the progenitors of these sources and/or the environment in which they form might influence the type of phenomena the resulting magnetar displays. Several of the AXPs appear to be associated with supernova remnants, while embedded clusters of massive stars have been found in the immediate vicinity of some SGRs. Since both AXPs and SGRs are distributed close to the Galactic plane, high extinction makes studies in the optical difficult. We present early results from our Spitzer program aimed at probing the environmental factors that might contribute to the difference in the observed characteristics between AXPs and SGRs. 相似文献
53.
N K Patel T T Medhavy C Patnaik A Hussain 《Journal of the Indian Society of Remote Sensing》1995,23(2):33-39
Microwave sensors having all-weather capabilities provide an opportunity to monitor rice grown in monsoon season. An attempt has been made to identify rice crop using multitemporal ERS-1 SAR data in C-band (5.3 GHz). Data acquired on August 15 (D1), September 19 (D2), October 24 (D3) and November 28 (D4) 1993 were taken. Combinations of data acquired on different dates were used for identification of rice crop. Single-date IRS-1B LISS II data in visible and NIR bands acquired on October 23, 1993 was also used for comparison of estimated rice area. Analysis of the results has shown that a combination of SAR data acquired at the tillering (August), booting (September) and heading (October) stages of rice crop enabled identification and area estimation of rice crop grown under lowland conditions. Single-date SAR data acquired in the month of October was found to be better for identification of rice compared to other dates. 相似文献
54.
Sushma Panigrahy S. S. Ray Anil Sood L. B. Patel P. K. Sharma J. S. Parihar 《Journal of the Indian Society of Remote Sensing》2004,32(2):209-216
A study was conducted in the Bathinda district of Punjab state for mapping the cropping pattern and crop rotation, monitoring
long term changes in cropping pattern by using the satellite based remote sensing data along other spatial and non-spatial
collateral data. Multi-date IRS LISS I and IRS WiFS sensor data have been used for this study. Cropping pattern maps and crop
rotation maps were generated for the years 1988-89 and 1998-99. The present study has shown the increase of cropping intensity
significantly, mainly due to increase in rice area. However, crop diversity has decreased mainly due to decline in the area
under the minor crops like pearl millet, gram, rapeseed/ mustard. There is increase in area coverage of cotton-wheat and rice-wheat
rotation, at the expense of the minor crops. 相似文献
55.
S. C. Patel S. Ravi S. S. Thakur T. K. Rao K. V. Subbarao 《Mineralogy and Petrology》2006,88(1-2):363-380
Summary Mineralogical characteristics of eclogite xenoliths from three kimberlite pipes (KL2, P2 and P10) of the Proterozoic Wajrakarur
kimberlite field of southern India have been studied. In a rare sample of enstatite eclogite from the KL2 pipe garnet contains
microscopic triangular arrays of needles or blebs of omphacite, enstatite and rutile consistent with an origin by exsolution
parallel to the isometric form {111}. Discrete omphacite grains in the sample contain exsolved needles or blebs of enstatite
and garnet. Kyanite eclogites are abundant in the KL2 pipe which occasionally show a secondary ring of pure celsian around
kyanite grains. Omphacite Na2O contents in the eclogites of the KL2 and P2 pipes are typically between 3 and 6 wt%, and garnet has widely variable composition
with end member ranges of Prp22-81Grs0-47Alm10-30Sps0-1Adr0-5Uv0-3. Eclogites of the P10 pipe comprise chromian omphacite
and garnet. Phase relations in the ACF projection exhibit systematic increase of the Ca-Tschermak’s component in omphacite
from enstatite eclogite through biminerallic eclogite to kyanite eclogite. Garnet-clinopyroxene Fe–Mg geothermometry yields
temperatures mostly in the range of 900–1100 °C. A formerly supersilicic nature of garnet in enstatite eclogite as inferred
from exsolution mineralogy indicates minimum peak pressure of 5 GPa. 相似文献
56.
M Poza NITA Bhagia J H Patel SUJAY Dutta V K Dadhwal 《Journal of the Indian Society of Remote Sensing》1996,24(4):243-254
I he aim of the piesent study was to suggest an approach for national level acreage estimation for wheat using satellite remote sensing data and demonstrate its perfromantee Multi-date moderate resolution (188 m) IRS-IC WiFS data sets were used as the core data Sampie segment approach with stratified random sampling was used for the data analysis For making meaningful comparisons over time, multi-date sets were geometncally registered and radiometrically normalised by extracting pseudo-invariant Features and performing regression analysis on the digital numbers of such features The corrected multi-temporal data sets were used in hierarchical classification scheme. The results of this exercise are presented. It appeals that there is an overestimatoin of wheat acreage The sampling effieieney was also low, indicating need to improve sampling strategy Some of the problems encountered and the corrections planned to overcome them are also discussed 相似文献
57.
Dhruvesh P. Patel Jorge A. Ramirez Prashant K. Srivastava Michaela Bray Dawei Han 《Natural Hazards》2017,89(1):93-130
Surat city of India, situated 100 km downstream of Ukai Dam and 19.4 km upstream from the mouth of River Tapi, has experienced the largest flood in 2006. The peak discharge of about 25,770 m3 s?1 released from the Ukai Dam was responsible for a disaster. To assess the flood and find inundation in low-lying areas, simulation work is carried out under the 1D/2D couple hydrodynamic modeling. Two hundred ninety-nine cross sections, two hydraulic structures and five major bridges across the river are considered for 1D modeling, whereas a topographic map at 0.5 m contour interval was used to produce a 5 m grid, and SRTM (30 and 90 m) grid has been considered for Surat and the Lower Tapi Basin. The tidal level at the river mouth and the release from the Ukai Dam during 2006 flood are considered as the downstream and upstream boundaries, respectively. The model is simulated under the unsteady flow condition and validated for the year 2006. The simulated result shows that 9th August was the worst day in terms of flooding for Surat city and a maximum 75–77% area was under inundation. Out of seven zones, the west zone had the deepest flood and inundated under 4–5 m. Furthermore, inundation is simulated under the bank protection work (i.e., levees, retaining wall) constructed after the 2006 flood. The simulated results show that the major zones are safe against the inundation under 14,430 m3 s?1 water releases from Ukai Dam except for the west zone. The study shows the 2D capability of new HEC-RAS 5 for flood inundation mapping and management studies. 相似文献
58.
This paper presents observations of SiO maser emission from 161 Mira variables distributed over a wide range of intrinsic
parameters like spectral type, bolometric magnitude and amplitude of pulsation. The observations were made at 86.243 GHz,
using the 10-4 m millimeter-wave telescope of the Raman Research Institute at Bangalore, India. These are the first observations
made using this telescope. From these observations, we have established that the maser emission is restricted to Miras having
mean spectral types between M6 and M10. The infrared period-luminosity relation for Mira variables is used to calculate their
distances and hence estimate their maser luminosities from the observed fluxes. The maser luminosity is found to be correlated
with the bolometric magnitude of the Mira variable. On an H-R diagram, the masing Mira variables are shown to lie in a region
distinct from that for the non-masing ones. 相似文献
59.
A method of seismic zonation based on deterministic modeling of rupture plane is presented in this work. This method is based
on the modeling of finite rupture plane along identified lineaments in the region using the semi-empirical technique, of Midorikawa
[(1993) Tectonophysics 218:287–295]. The modeling procedure follows ω2 scaling law, directivity effects, and other strong motion parameters. The technique of zonation is applied for technoeconomically
important NE part of Brahmaputra valley that falls in the seismic gap region of Himalaya. Zonation map prepared for Brahmaputra
valley for earthquakes of magnitude M > 6.0 show that approximately 90,000 km2 area fall in the highly hazardous zone IV, which covers region that can have peak ground accelerations of order more than
250 cm/s2. The zone IV covers the Tezu, Tinsukia, Dibrugarh, Ziro, North Lakhimpur, Itanagar, Sibsagar, Jorhat, Golaghat, Wokha, Senapati,
Imphal, and Kohima regions. The Pasighat, Daring, Basar, and Seppa region belong to zone III with peak ground accelerations
of the order 200–250 cm/s2. The seismic zonation map obtained from deterministic modeling of the rupture is consistent with the historical seismicity
map and it has been found that the epicenter of many moderate and major earthquakes fall in the identified zones. 相似文献
60.
Geology and geochemistry of giant quartz veins from the Bundelkhand Craton,central India and their implications 总被引:1,自引:0,他引:1
J. K. Pati S. C. Patel K. L. Pruseth V. P. Malviya M. Arima S. Raju P. Pati K. Prakash 《Journal of Earth System Science》2007,116(6):497-510
Giant quartz veins (GQVs; earlier referred to as ‘quartz reefs’) occurring in the Archean Bundelkhand Craton (29,000 km2) represent a gigantic Precambrian (∼2.15 Ga) silica-rich fluid activity in the central Indian shield. These veins form a
striking curvilinear feature with positive relief having a preferred orientation NE-SW to NNE-SSW in the Bundelkhand Craton.
Their outcrop widths vary from ≤1 to 70m and pervasively extend over tens of kilometers along the strike over the entire craton.
Numerous younger thin quartz veins with somewhat similar orientation cut across the giant quartz veins. They show imprints
of strong brittle to ductile-brittle deformation, and in places are associated with base metal and gold incidences, and pyrophyllite-diaspore
mineralization. The geochemistry of giant quartz veins were studied. Apart from presenting new data on the geology and geochemistry
of these veins, an attempt has been made to resolve the long standing debate on their origin, in favour of an emplacement
due to tectonically controlled polyphase hydrothermal fluid activity. 相似文献