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71.
Gargi Upadhyay S. S. Ray Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2008,36(1):37-50
Crop phenological parameters, such as the start and end time of the crop growth, the total length of the growing season, time of peak vegetation and rate of greening and senescence are important for planning crop management and crop diversification/intensification. Multi-temporal remote sensing data provides opportunity to characterize the crop phenology at regional level. This study was conducted during the kharif season of the year 2001–02 for Punjab. The ten-day Normalised Difference Vegetation Index (NDVI) composite products, with 1 km spatial resolution, available from the Vegetation sensor onboard SPOT4 were used for the study. Twenty-one temporal datasets from May 1, 2001 to November 21, 2001 were used. Logical modelling approach was followed to compute the minimum and maximum NDVI, the amplitude of NDVI, the threshold NDVI during sowing and harvest, the crop duration, integrated NDVI and skewness of profile. The analysis showed that before July beginning, in the whole of Punjab, sowing/planting was over. It was found that the crop emergence in the eastern part of the state started earlier than the western region. The maximum NDVI, which represented peak vegetative stage, was above 0.7 and occurred mostly during August. The duration of crops ranged between 90–140 days, with majority between 110–120 days. Total integrated NDVI in Punjab was generally above 60. Using principal component analysis and divergence analysis seven best metrics were selected for crop discrimination. 相似文献
72.
73.
R.K. Manchanda 《Astrophysics and Space Science》2002,282(1):149-160
The spectral and temporal measurements in the hard X-ray region between 20-200 keV not only determines the extended behaviour
of thermal X-ray spectrum below 10 keV but also provide a unique insight into the non-thermal processes in relativistic astrophysical
plasma. From our present understanding of the X-ray sources, a significant fluxin the 20-200 keV band is expected from a variety
of astrophysical phenomena, however, the available spectral data on the galactic and extragalactic X-ray source is very limited.
This is mainly due to the fact that sensitivity of the detector systems used for earlier measurements was relatively poor.
Since 1997, we have been carrying out a programme of hard X-ray observations galactic and extragalactic sources, in the 20-200
keV energy band using a highly sensitive balloon borne experiment. The X-ray telescope consists of three modules of large
area scintillation counters specially configured in the back-to-back geometry and have a combined sensitivity of ∼ 10-6 ph cm-2 s-1 keV-1 for an on-source observations of 3 hrs. A total of 30 hours of ceiling data above an altitude of 3 mbar has been collected
in 4 successful balloon flights from Hyderabad, India. Almost a dozen galactic and extragalactic X-ray sources were targeted
and tracked during these observations. A positive detection was made in each case and in some cases the observed spectra extended
right up to 150 keV. A brief account of the observed spectral and temporal features on some of the sources along with accurate
measurement of diffuse background spectrum and a weak gamma ray burst will be presented in the paper.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
74.
K. Pandarinath Sushma Prasad R. D. Deshpande S. K. Gupta 《Journal of Earth System Science》1999,108(2):107-116
A 54-m long core was raised from the bed of the Nal Sarovar, a large shallow lake located in the middle of the low-lying region
linking the Gulfs of Kachchh and Khambhat, in western India. A three-layer sequence comprising: Zone-1 (top 3 m), predominantly
silty-clay/clayey; Zone-2 (3–18 m), sandy; and Zone-3 (18–54 m), dominated by sticky silty-clay/clayey-silt with occasional
thin sand layers and basalt fragments was identified. Smectite and illite are the dominant clay minerals with minor amounts
of kaolinite and chlorite. Very high content of smectite (53–97%) in the clays of the lowermost zone (18–54 m) and the geomorphic
features of the surrounding region suggested that the sediments were derived from the basaltic terrain of Saurashtra and/or
via the Gulf of Khambhat. The clay content in the middle zone (3–18 m), dominantly sandy, is very low. Therefore, provenance
for this zone was derived using heavy minerals in the sand fraction. The heavy mineral species in this zone suggested the
mixed metamorphic and igneous terrain of Aravallis as the major source. The grain-size distribution of this zone closely matched
with the sediments underlying the modern Sabarmati riverbed at Ahmedabad, suggesting fluvial depositional environment. Clays
also dominate sediments of the topmost (0–3 m) zone with illite as the dominant (74–81%) specie followed by smectite suggesting
derivation from the mixed metamorphic and igneous terrain of Aravallis. 相似文献
75.
R. K. Manchanda 《Astrophysics and Space Science》1983,91(2):455-460
A possible evidence of a 300 d period in the hard X-ray intensity of CygX-1 is deduced by a re-analysis of the available data between 1964 and 1978. It is suggested that the long term periodicity may be due to the presence of a third body in the system which will also explain in a natural way the large mass problem is assigned to the X-ray source. 相似文献
76.
77.
S. Natarajan N. Y. Gajbe M. L. Manchanda 《Journal of the Indian Society of Remote Sensing》1986,14(1):17-24
A soil and land use survey of Mewat area, Haryana, was carried out using the aerial photographs of 1:50,000. Four major physiographic units namely hills, piedmont plain, intermontante basin and Yamuna alluvial plain were recognised. The land use was studied in relation to the physiographic units. The legend adopted for land use classification has physiography at first level, utility at second level and management and identification at third and fourth levels respectively. Of the total area of 161,103 ha surveyed, 131,637 ha (81.72%) are cultivated. Of this 75,967 ha (47.16%) irrigated and 55,670 ha (34.56%) is unirrigated. Under uncultivated area, barren lands cover 14,224 ha (8.82%), forests occupy 3,463 ha (5.25%), settlements cover 3,300 (2.05%), water bodies occupy 1,312 ha (0.81%) and roads, railway lines, canals and drains constitute 2,167 ha (1.55%). 相似文献
78.
In the present study an attempt has been made to interpret visually the computer transformed, FCC, PC1-PC2 and Δ method products, landsat imagery of different seasons and with different crop cover, of salt affected areas of part of Haryana. FCC and PC1-PC2 of moist hot climate (10 October, 1972) was found better for physiographic interpretation than other seasons and bands, Δ method (October. 1972) and FCC of hot-dry season were good only for interpreting salt affected areas whereas other landform features were suppressed. Not much additional information was gained by way of PC1-PC2 and Δ method transformation over FCC (bands 4, 5, 7). It was possible to delineate different classes of salt effected soils based on the areal extent of the hazard. 相似文献
79.
Y. Fukada S. Hayakawa I. Kasahara F. Makino Y. Tanaka H. Akiyama M. Matsuoka J. Nishimura M. Oda M. Nakagawa H. Sakurai V. S. Iyenger P. K. Kunte R. K. Manchanda B. V. Sreekantan 《Astrophysics and Space Science》1976,42(1):245-248
The size of the hard X-ray source in the Crab Nebula was observed with scintillation counters on board two balloons at a lunar occulatation on 24 January, 1975. The Gaussian width of the source is 34 (+17, –14) and the center thereof is offset from the pulsar by 6±4 at position angle 102°. The observed time profile can also be fitted to an alternative model of two line sources whose intensities are 48% at 11 and 25.5% at 7 on both sides of the pulsar.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975. 相似文献
80.
Pramod Kumar Sudhir Kumar M. L. Manchanda 《Journal of the Indian Society of Remote Sensing》2004,32(1):81-90
Various attributes can be derived from Digital Elevation Model (DEM), which are essential to analyze watershed physical characteristics. This paper discusses utility and accuracy of satellite DEM surfaces and their derivatives. Facilities available in various software packages were compared to generate DEM from satellite data and other sources. For test site at Chamba, Uttaranchal, DEMs produced from various algorithms were evaluated for accuracy of surface and its derivatives. Most of the algorithms have shown correlation coefficient of 0.99 and above but the desirable maximum error in spot height (1/5 of contour interval) is not achieved. Slope and aspect produced from various algorithms were comparable around 70-80%. Comparison of DEM surface and its derivatives were attempted for test sites at Shimla and Nahan using IRS-1C and SPOT PAN stereo pair, respectively. Model accuracy has shown that error in height is higher than planimetry. Surface derivatives from stereo DEM for Shimla and Nahan test sites have shown an overall accuracy of 56.5% and 59.2% for slope; 49.79% and 71.21% for aspect and 74.15% for topographic level slicing, respectively. Accuracy has improved when observed class value was lowered or put-up by one unit. 相似文献