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排序方式： 共有514条查询结果，搜索用时 31 毫秒
431.
D. Bala Subrahamanyam Radhika Ramachandran S. Indira Rani S. Sijikumar T. J. Anurose Asish Kumar Ghosh 《Natural Hazards》2012,61(3):893-910
Accurate knowledge of different meteorological parameters over a launch site is very crucial for efficient management of satellite
launch operations. Local weather over the Indian satellite launch site located at Sriharikota High Altitude Range (SHAR: 13.72°N,
80.22°E) is very much dependent on the atmospheric circulation prevailing over the Bay of Bengal oceanic region and topography-induced
convective activities. With a view to providing severe weather threat prediction in terms of launch commit criteria (LCC),
two numerical atmospheric models namely high-resolution regional model (HRM) and advanced regional prediction system (ARPS)
are made operational over SHAR in a synoptic and mesoscale domain, respectively. In the present research article, two launch
campaigns through Polar Satellite Launch Vehicle (PSLV-C11 and PSLV-C12) when contrasting weather conditions prevailed over
the launch site are chosen for demonstration of potential of two models in providing location-specific short-to-medium-range
weather predictions meeting the needs of LCC. In the case of PSLV-C11 campaign, when the launch site underwent frequent thundershower-associated
rainfall, ARPS model–derived meteorological fields were effectively used in prediction of probability of the wet spells. On
the other hand, Bay of Bengal underwent severe cyclonic storm during PSLV-C12 campaign, and its formation was reasonable captured
through HRM simulations. It is concluded that a combination of HRM and ARPS provide reliable short-to-medium-range weather
prediction over SHAR, which has got profound importance in launch-related activities. 相似文献
432.
Variogram Fractal Dimension Based Features for Hyperspectral Data Dimensionality Reduction 总被引：1，自引：0，他引：1
Kriti Mukherjee Jayanta K Ghosh Ramesh C. Mittal 《Journal of the Indian Society of Remote Sensing》2013,41(2):249-258
In this paper a new approach for fractal based dimensionality reduction of hyperspectral data has been proposed. The features have been generated by multiplying variogram fractal dimension value with spectral energy. Fractal dimension bears the information related to the shape or characteristic of the spectral response curves and the spectral energy bears the information related to class separation. It has been observed that, the features provide accuracy better than 90 % in distinguishing different land cover classes in an urban area, different vegetation types belonging to an agricultural area as well as various types of minerals belonging to the same parent class. Statistical comparison with some conventional dimensionality reduction methods validates the fact that the proposed method, having less computational burden than the conventional methods, is able to produce classification statistically equivalent to those of the conventional methods. 相似文献
433.
Abstract The normalized antecedent precipitation index (NAPI) model by Heggen for the prediction of runoff yield is analytically derived from the water balance equation. Heggen's model has been simplified further to a rational form and its performance verified with the Soil Conservation Service Curve Number (SCS-CN) model. The simplified model has three coefficients specific to a watershed, and requires two inputs: rainfall and the derived parameter, NAPI. The characteristic behaviour of the NAPI has resonance with the curve number (CN) of the SCS model. The proposed NAPI model was applied to three watersheds in the semi-arid region of India to simulate runoff yield. The model showed improved correlation between the observed and predicted runoff data compared to the SCS-CN model. The F test and paired t test also confirmed the reliability of the model with significance levels of 0.01 and 0.001%, respectively. The proposed model could be used successfully for rainfall–runoff modelling in a watershed. Citation Ali, S., Ghosh, N. C. & Singh, R. (2010) Rainfall–runoff simulation using a normalized antecedent precipitation index. Hydrol. Sci. J. 55(2), 266–274. 相似文献
434.
AbstractThe objective of this study is to measure the balance of water demand versus water resource availability in an interfluve of West Bengal, India to support water resource planning, particularly of inter-basin transfers. Surface water availability was modelled using the US Soil Conservation Service curve number (SCS-CN) approach, whilst groundwater availability was modelled based on water-level fluctuations and the rainfall infiltration method. Water use was modelled separately for the agricultural, industrial, and domestic sectors using a predominantly normative approach and water use to availability ratios calculated for different administrative areas within the interfluve. Overall, the approach suggested that the interfluve receives 327 × 106 m3 year-1 of excess water after satisfying these sectoral demands, but that the eastern part of the study area is in deficit. However, a sensitivity analysis carried on the approach to several assumptions in the model suggested changed circumstances would produce surplus/deficit ranging from ?215 × 106 to 435 × 106 m3 year-1 . The approach could have potential for localised water balance modelling in other Indian catchments.
Editor D. Koutsoyiannis; Associate editor D. Hughes 相似文献
435.
The 8 October 2005 earthquake caused widespread destruction in both the state of Jammu and Kashmir of India and Northern Pakistan. Due to poor accessibility in the hazardous and difficult mountainous terrain, a proper and comprehensive ground-based survey was not possible. However, with the help of remote sensing data and its analysis techniques, it is feasible to undertake both earthquake-related damage identification and assessment. This study attempts to document and identify built-up damaged (BD) areas using spectral indices taking temporal multispectral images from IRS-P6 LISS-IV. Five spectral indices have been used to identify BD areas using supervised possibilistic c-means (PCM) and noise cluster (NC) classifiers, to analyse the satellite data. The result indicates that Class Based Sensor Independent (CBSI) based Transformed Normalized Difference Vegetation Index (TNDVI) temporal indices provide the best results for identifying BD areas, while Simple Ratio (SR) index gives the best results for built-up undamaged area identification. Further, it observed that PCM classifier performed better in comparison to NC classifier. 相似文献
436.
An exact solution is obtained for a thick domain wall in a five dimensional Kaluza-Klein space time within the framework of
Lyra geometry. The space time is nonsingular both in its spatial and temporal behavior. It is shown that the domain wall has
no particle horizon and the gravitational force due to them is attractive.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
437.
Mid Wave Infra Red (MWIR) region of the electromagnetic spectrum is a key region that is exploited for long range infrared reconnaissance and surveillance applications. Detecting enemy targets and being undetectable is the prime requirement of the modern warfare. In the present study MWIR hyperspectral imaging has been exploited for detection of camouflaged targets in the scene. Detection methodology has been developed using unsupervised target detection algorithms (Reed Xiaoli, K-Means and ISODATA). Methodology has been successfully tested in extracting camouflaged targets from the background. Performance results have been compared. The proposed methodology may in future be applied in detection and identification of gases and minerals in the field. 相似文献
438.
Zn-bearing minerals that act as indicator minerals for base metal sulphide mineralization from the Proterozoic Betul Belt,
central India with special emphasis on their genetic significance have been discussed. Sulphide mineralisation is hosted by
the felsic volcanic rocks and has similarities with volcanic-hosted massive sulphide deposits in other parts of the world.
Synvolcanic hydrothermal alteration is crudely zoned with an inner high Mg-Ca core and an outer wider envelop of Al-Fe rich
mineral assemblage. Most of the prospects have strata bound, moderately to steeply dipping, multiple, sub-parallel sheet like
ore bodies composed of disseminated and semi-massive to massive ores. Zn-bearing spinel, staurolite, biotite and ilmenite
typically occur within the foot-wall alteration zones in close proximity to the sulphide mineralization. Zincian spinel is
ubiquitous irrespective of the nature of alteration zone. Zincian staurolite is nearly absent in Mg-Ca alteration zones but
commonly present in Al-Fe alteration zone along with zincian ilmenite. Zn-bearing biotite in intimate association with zincian
spinel is generally found in Mg-Ca alteration zone and in the transition to Al-Fe alteration zone. Most of these indicator
minerals can be considered as products of desulphidation of sphalerite during metamorphism. Mechanisms other than desulphidation
like formation of gahnite by overstepping of the zinc saturation limit of biotite during retrogression to chlorite and formation
of zincian staurolite at the expense of gahnite is also recorded. Field presence of these minerals has immense significance
in exploration in Betul Belt as they occur in close spatial relationship with the sulphide rich zones and therefore act as
direct vectors to ore. 相似文献
439.
Fractal geometry provides a means for describing and analysing the complexity of various features present in digital images. In this paper, characteristics of Fractal based compression of satellite data have been tested for Indian Remote Sensing (IRS) images (of different bands and resolution). The fidelity and efficiency of the algorithm and its relationship with spatial complexity of images is also evaluated. Results obtained from fractal compression have been compared with popularly used compression methods such as JPEG 2000, WinRar. The effect of bands and pixel resolution on the compression rate has also been examined. The results from this study show that the fractal based compression method provides higher compression rate while maintaining the information content of RS images to a great extent than that of JPEG. This paper also asserts that information loss due to fractal compression is minimal. It may be concluded that fractal technique has many potential advantages for compression of satellite images. 相似文献
440.