Cost analysis to determine optimum geometry of a retreating longwall face     

Santanu Majumdar  Subhas C. Ray 《Geotechnical and Geological Engineering》1983,1(3):261-266

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Analysis of cropping pattern changes in Bathinda district,Punjab     

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   

Use of GIS and remote sensing for crop diversification — a case study for Punjab state     

S. S. Ray  Anil Sood  Gargi Das  Sushma Panigrahy  P. K. Sharma  J. S. Parihar 《Journal of the Indian Society of Remote Sensing》2005,33(2):181-188

In this study, an attempt has been made to suggest crop diversification based on soil and weather requirements of different crops. State level spatial databases of various agro-physical parameters such as rainfall, soil texture, physiography and problem soil along with the agricultural area derived from remote sensing data were integrated using GIS. A raster based modelling approach was followed to arrive at suitable zones for practicing different cropping systems. The results showed that the south-western Punjab is suitable for low water requiring crops such as desi cotton, pearl millet, gram etc., where as north-eastern Punjab with high rainfall and excess drainage should practice maize based cropping system. Rice can be substituted by maize and other crops in Central Punjab, where water table is going down fast. Using this approach the area of rice based cropping system can be reduced from present 24.7 lakh ha to 19.6 lakh ha, thereby reducing the degradation of valuable land and water resources.  相似文献   

Water quality assessment of Gautami — Godavari mangrove estuarine ecosystem of Andhra Pradesh, India during September 2001     

S. C. Tripathy  A. K. Ray  S. Patra  V. V. Sarma 《Journal of Earth System Science》2005,114(2):185-190

Some chemical and biological parameters were analysed at sixteen stations in the mangrove ecosystem, of the neighbouring Gautami-Godavari (GG) river estuary and Kakinada (KKD) bay to understand the present status of water quality and the impact of external terrigenous inputs during southwest (SW) monsoon in the study areas. High concentrations of nutrients in the mangrove ecosystem compared to the bay and estuarine ecosystems reveal the importance of this zone as a source of nutrients to the adjacent coastal ecosystems. Low Si:N:P (29:4:1) ratios in these ecosystems are due to the enrichment of these nutrients through external anthropogenic inputs even after the utilization by phytoplankton in the biological cycle. The mean Chl b/Chla and Chl c/Chla ratios and high phaeopigments (Pp) concentrations compared to Chlb and high ratios of Chl a/Pp suggests the possibility of the potential growth of phytoplankton populations in lower light intensity and low turbulent areas of these mangrove ecosystems.  相似文献   

Accuracy assessment of InSAR derived input maps for landslide susceptibility analysis: a case study from the Swiss Alps   总被引：2，自引：0，他引：2  

Lalan P. Singh  C. J. van Westen  P. K. Champati Ray  P. Pasquali 《Landslides》2005,2(3):221-228

In recent years SAR interferometry has become a widely used technique for measuring altitude and displacement of the surface of the earth. Both these capabilities are highly relevant for landslide susceptibility studies. Although there are many problems that make the use of SAR interferometry less suitable for landslide inventory mapping, it’s use in landslide monitoring and in the generation of input maps for landslide susceptibility assessment looks very promising. The present work attempts to evaluate the usefulness and limitations of this technique based on a case study in the Swiss Alps. Input maps were generated from ERS repeat pass data using SAR interferometry. A land cover map has been generated by image classification of multi-temporal SAR intensity images. An InSAR DEM was generated and a number of maps were derived from it, such as slope-, aspect, altitude- and slope form classes. These maps were used to generate landslide and rockfall susceptibility maps, which give fairly well acceptable results. However, a comparison of the InSAR DEM with the conventional Swisstopo DEM, indicated significant errors in the absolute height and slope angles derived from InSAR, especially along the ridges and in the valleys. These errors are caused by low coherence mostly due to layover and shadow effects. Visual comparison of stereo images created from hillshading maps and corresponding DEMs demonstrate that a considerable amount of topographic details have been lost in the InSAR-derived DEM. It is concluded that InSAR derived input maps are not ideal for landslide susceptibility assessment, but could be used if more accurate data is lacking.  相似文献   

Testing the relation between UV–vis color and TiO₂ content of the lunar maria     

Jeffrey J. Gillis-Davis  Paul G. Lucey  B. Ray Hawke 《Geochimica et cosmochimica acta》2006,70(24):6079-6102

Reflectance spectroscopy is important for placing lunar samples into a regional and global geologic context. To this end, the ultraviolet–visible (UV–vis) color ratio, used to estimate the TiO₂ composition of mature mare basalts, has been one of the most widely used spectral parameters in lunar exploration. We examine the correlation between UV–vis color and TiO₂ content using a combination of Clementine, Lunar Prospector, and sample data to document the extent to which color is dependent upon TiO₂. Examination of the remotely sensed data reveals that the correlation between UV–vis ratio and TiO₂ composition is best represented by a sigmoidal trend rather than the canonical linear or curvilinear correlation. With this information, we are then able to evaluate between two models that propose different explanations for the relationship between UV–vis color and TiO₂. The first model attributes the correlation between TiO₂ and UV–vis color to spectrally neutral opaques (i.e., ilmenite), while the other emphasizes the effect of Fe–Ti charge-transfer in lunar glasses and dual scattering mechanisms between high- and low-Ti basalts. We do not find evidence in the spectral data to support the occurrence of Fe–Ti charge-transfer in lunar glass as the principal cause for color in high-Ti basalts. The data also do not substantiate the existence of different scattering mechanisms (e.g., volume v. surface scattering) between high- and low-TiO₂ basalts. Instead, our analyses substantiate that the spectral effects of ilmenite exhibit a major influence over the UV–vis ratio. By including sample data we find that in addition to ilemenite/TiO₂ content, factors such as FeO content, ilmenite grain size, modal abundance of plagioclase, and the olivine-to-pyroxene ratio in a mare soils can influence the UV–vis continuum. These findings point to promising avenues of research that future UV–vis spectral techniques can exploit in order to yield more accurate TiO₂ estimates and potentially additional petrologic information.  相似文献   

Open system alkaline magmatism in northern Kenya: evidence from U-series disequilibria and radiogenic isotopes   总被引：4，自引：0，他引：4  

Stuart Black  Ray Macdonald  Barbara A. Barreiro  Peter N. Dunkley  Martin Smith 《Contributions to Mineralogy and Petrology》1998,131(4):364-378

U-series activity ratios, Sr-Nd-Pb isotopic ratios and major and trace element compositions have been determined on young basalts (<10 ka) and trachytes from the volcano Emuruangogolak in the Kenya Rift Valley. The basalts are mildly alkaline and are associated with small volumes of hawaiite. The mafic rocks are characterised by high (²³⁰Th/²³²Th) (≥1.06) with low (²³⁸U/²³⁰Th) ratios (≤0.72). They have variable incompatible trace element ratios (e.g. Zr/Nb, Ba/Zr), indicating that they represent a number of magmatic lineages. The trachytes, which comprise both comenditic and pantelleritic varieties, have significantly lower (²³⁰Th/²³²Th) ratios than the basalts, with clear differences between pantelleritic and comenditic types. The (²³⁸U/²³⁰Th) ratios in the pantellerites range from less, to greater, than 1. The variations in composition and isotopic diversity must represent different sources for the trachytes. Internal isochrons for the trachytes give U-Th ages of 14 to 40 ka, similar to single crystal laser fusion ⁴⁰Ar/³⁹Ar ages from sanidine phenocrysts (16–38 ka) for the same rocks. Post-crystallisation residence times of the trachytes were very short, implying relatively rapid movement of trachyte from magma chamber to the surface. Variations in the initial (²³⁰Th/²³²Th)₀ ratios (0.69–1.14) of both basalts and trachytes indicate that Emuruangogolak has erupted a large range of isotopically diverse magmas over a very short period of time (38 ka), from conduits closely spaced around the summit of the volcano. Received: 29 May 1996 / Accepted: 24 November 1997  相似文献   

Flow and sediment transport over large subaqueous dunes: Fraser River,Canada     

Jan H. Van Den Berg  Andr Van Gelder  Ray Kostaschuk  Paul Villard 《Sedimentology》1998,45(1):217-221

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Angular momentum of Arctic Ocean tides     

R. D. Ray  B. F. Chao  Z. Kowalik  A. Y. Proshutinsky 《Journal of Geodesy》1997,71(6):344-350

Oceanic tidal angular momentum (OTAM) is calculated for the four major tides of the Arctic Ocean, based on the tidal elevations and current velocities from a recent two-dimensional numerical hydrodynamic model. The presented OTAM tables are meant to be complementary to other modeling studies that use satellite altimetry (which cannot observe Arctic Ocean tides because of ice cover and limited satellite inclinations). Although the Arctic Ocean's influence on earth rotation is, as may be expected, relatively small, the rapid advancement of the subject now calls for such small contributions to be explicitly accounted for. Received: 22 January 1996; Accepted: 5 December 1996  相似文献   

The acute toxicity of silver to some freshwater fishes     

B. S. Khangarot  P. K. Ray 《洁净——土壤、空气、水》1988,16(5):541-545

In the batch experiment with daily exchange of medium the acute toxicity of Ag from AgNO₃ to Channa punctatus, Lebistes reticulatus and Puntius sophore is determined over 12 to 96 h exposure. In general, the sensitivity of species increases in the order mentioned. The LC_{50, 96h} are 18.89 μg/l Ag for Channa punctatus, 7.55 μg/l Ag for Puntius sophore and 6.44 μg/l for Lebistes reticulatus. For 12 and 48 h exposure the values in the same order of species are: 62 and 30, 44 and 14 as well as 57 and 16 μg/l Ag.  相似文献