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21.
Natural Hazards - Avalanche forecasting is carried out using physical as well as statistical models. All these models have certain limitations associated with their mathematical formulation that... 相似文献
22.
Prajapati V. K. Khanna M. Singh M. Kaur R. Sahoo R. N. Singh D. K. 《Natural Hazards》2021,109(1):89-109
Natural Hazards - The present study was carried out to characterize drought in the Marathwada region of Maharashtra, which experiences recurring droughts, through meteorological, hydrological and... 相似文献
23.
R. Kaur Rudy Wijnands Alessandro Patruno Vincenzo Testa GianLuca Israel Nathalie Degenaar Biswajit Paul Brijesh Kumar 《Monthly notices of the Royal Astronomical Society》2009,394(3):1597-1604
We present results from our Chandra and XMM–Newton observations of two low-luminosity X-ray pulsators SAX J1324.4−6200 and SAX J1452.8−5949 which have spin periods of 172 and 437 s, respectively. The XMM–Newton spectra for both sources can be fitted well with a simple power-law model of photon index, Γ∼ 1.0 . A blackbody model can equally well fit the spectra with a temperature, kT ∼ 2 keV, for both sources. During our XMM–Newton observations, SAX J1324.4−6200 is detected with coherent X-ray pulsations at a period of 172.86 ± 0.02 s while no pulsations with a pulse fraction greater than 18 per cent (at 95 per cent confidence level) in 0.2–12 keV energy band are detected in SAX J1452.8−5949 . The spin period of SAX J1324.4−6200 is found to be increasing on a time-scale of which would suggest that the accretor is a neutron star and not a white dwarf. Using subarcsec spatial resolution of the Chandra telescope, possible counterparts are seen for both sources in the near-infrared images obtained with the son of infrared spectrometer and array camera (SOFI) instrument on the New Technology Telescope. The X-ray and near-infrared properties of SAX J1324.4−6200 suggest it to be a persistent high-mass accreting X-ray pulsar at a distance ≤8 kpc . We identify the near-infrared counterpart of SAX J1452.8−5949 to be a late-type main-sequence star at a distance ≤10 kpc, thus ruling out SAX J1452.8−5949 to be a high-mass X-ray binary. However, with the present X-ray and near-infrared observations, we cannot make any further conclusive conclusion about the nature of SAX J1452.8−5949 . 相似文献
24.
Major ion chemistry of Renuka Lake and weathering processes, Sirmaur District, Himachal Pradesh, India 总被引:2,自引:0,他引:2
Renuka Lake in the Lesser Himalaya, Himachal Pradesh is in a valley surrounded by mountains comprised of highly crumpled, shattered, crushed, folded and dislocated rocks consisting of carbonaceous shales-slates often pyrite-ferrous, limestone, quartzites, boulder beds, etc. A detailed and systematic study of the major ion chemistry of the lake, clay mineral composition of the bed and core sediments and the Pb210 isotope estimation in the latter was conducted. The chemistry is dominated by carbonate weathering and (Ca + Mg) and (HCO3 + SO4) accounts for about 90% of the cations and anions. The SO4 content is almost the same as the HCO3. The low contribution of (Na + K) to the total cations and the (Ca + Mg) and HCO3 data tends to indicate that silicate weathering has not been the potential source of major ions to the lake waters. This difference may be related to the increasing susceptibility to weathering of carbonate over silicate rocks exposed in the catchment and also seepage of water at the bottom. The high sulphate content in waters is derived from dissolution of pyrite-ferrous reduced black shales, which constitute a significant lithology in the catchment. The chemical index of alteration (CIA) value in core sediments is on an average 76, which is comparable with average shale (70-75) and the rate of sedimentation 3.3 mm/year based on measurement of Pb210, indicating a fairly high weathering rate in the catchment. Illite is the dominant clay mineral (52-90%) in the bed and core sediments, chlorite constitutes 7-48% and the kaolinite-chlorite mixed silicate layer is l-2%. This is consistent with the shale-slate, sandstone lithology in the valley. 相似文献
25.
R. N. Sahoo M. Bhavanarayana B. C. Panda C. N. Arika R. Kaur 《Journal of the Indian Society of Remote Sensing》2005,33(1):17-23
Accurate estimation of soil moisture through remote sensing technique has been a challenge till date. In optical and thermal
remote sensing, there is no index developed to detect the changes in soil moisture levels. In microwave region, soil roughness
and other target parameters equally affect the technique for soil moisture estimation. Therefore, a computational technique
in C language based on Shannon’s Information Theory (Shannon, 1948) has been developed to calculate total information content
from multispectral radiometer data. The total information content is a compressed single value, which quantifies the information
content of soil spectral reflectance in the electromagnetic spectrum range (400–1100 nm) under study. This technique was tested
over a wide range of soil moisture levels. The study revealed that as compared to other techniques total information content
index is very sensitive to change in moisture content of soil. This technique could not only quantify the soil moisture content
in optical and near infra red region, but also led to a simplified one dimensional separability and clustering analysis. 相似文献
26.
Minakshi P.K. Sharma Amandeep Kaur Vanita Shalley 《Journal of the Indian Society of Remote Sensing》2005,33(1):63-68
This study reveals the temporal changes in the land use/land cover of district Ludhiana from the years 1970 to 2001 and reports
on the change that has occurred in land use/land cover as a result of change in cropping pattern. The changes were analysed
through the data obtained from statistical abstract 1969–70, False Colour Composite (FCC) of IRS-IC LISS-III satellite data
of March 2001 and ground truth. There has been a decrease in agricultural land by 2100 ha. but still it occupies 83.76% of
the total geographical area (TGA). The wasteland shows a declining trend whereas forest cover has increased from 1.07 to 2.71%
of TGA. Area under non-agricultural uses has increased from 10.13 to 12.50% of TGA. There has also been a great change in
the cropping pattern of the district. Crops such as groundnut, gram and cotton have nearly disappeared and wheat and rice
dominate the region. This change has substantially resulted in the decrease of area under wastelands. 相似文献
27.
S. K. Deb Inderpreet Kaur C. M. Kishtawal P. K. Pal 《Theoretical and Applied Climatology》2014,115(3-4):693-702
The operational derivation of atmospheric motion vectors (AMVs) using infrared (10.5–12.5 μm) and water vapor (6.3–7.1 μm) channels of successive geostationary satellite images started in the 1980s. Subsequently, AMVs have become an important component for operational numerical weather prediction throughout the globe for the last decade or so. In India, at the Space Applications Centre, Indian Space Research Organisation, the operational derivation of AMVs (infrared winds and water vapor winds) from the Indian geostationary satellite Kalpana-1 has been initiated a few years back. Recently, an L-band radar lower atmosphere wind profiler (LAWP) has been installed at the National Atmospheric Research Laboratory, Gadanki located at (13.58°N, 79.28°E) for continuous high-resolution wind measurements in the lower atmosphere. In this study, a comparison of Kalpana-1 AMVs with wind measurements from LAWP and radiosonde has been carried out for a period of one and a half years. The performances of Kalpana-1 AMVs are also assessed by a separate comparison of Meteosat-7 AMVs, derived at the European Organisation for the Exploitation of Meteorological Satellites, with wind measurements from LAWP and radiosonde. Both sets of comparison show that AMVs from Kalpana-1 and Meteosat-7 are comparable over the Indian Ocean region. 相似文献
28.
S. K. Deb Steve Wanzong C. S. Velden Inderpreet Kaur C. M. Kishtawal P. K. Pal W. P. Menzel 《Journal of the Indian Society of Remote Sensing》2014,42(4):679-687
The real-time operational use of atmospheric motion vectors (AMVs) at numerical weather prediction (NWP) centers in India are being adversely affected due to inaccurate height assignment of cloud tracers, especially in thin semi-transparent clouds. In India, the operational derivation of AMVs from the Indian geostationary satellite Kalpana-1 began few years ago. A statistical empirical method (SEM) of height assignment, based on a genetic algorithm, is currently used to estimate the height of the retrieved vectors from Kalpana-1. This method has many limitations. In this paper, attempts have been made to implement the widely used and well tested height assignment methods such as the infrared window (WIN) technique, the H2O intercept, and the cloud base method in the Kalpana-1 AMV retrieval algorithm. The new height assignment algorithm significantly improves the statistics of the retrieved winds when compared to radiosondes, especially in high and mid levels winds. 相似文献
29.
Pesticide sorption on to the soil has a significant role in deciding the fate and behavior of pesticides in soil and aquatic environment. The present study investigates the adsorption of monocrotophos (MCP) and dichlorvos (DDVP) on the three soils of Malwa region of Punjab, India under different conditions. Batch adsorption experiments were preformed in replicates using 2 g of air‐dried soil and varying concentrations of pesticides and 20 mL of 0.01 M CaCl2 as background electrolyte. The results revealed high adsorption of MCP and DDVP in soil B with kf‐values 0.1261 and 0.0498 and n‐values 2.7345 and 1.831, respectively. The adsorption isotherms obtained were analyzed and the data was subjected to classical Langmuir, Freundlich, and Temkin models. The experimental data best fitted to the logarithm form of Freundlich and Temkin model. Kinetics analyses were performed using pseudo‐first order, pseudo‐second order, and intraparticle diffusion models. The regression results showed that the experimental data fitted very well with the pseudo‐second order kinetic model as correlation coefficient value is very closer to 1 and also followed the intraparticle diffusion model, whereas, diffusion is not only the rate controlling step. The percentages desorption with tap and distilled water is 32–64% for MCP and 25–48% for DDVP. 相似文献
30.
D. Kaur N. K. Bhardwaj R. K. Lohchab 《International Journal of Environmental Science and Technology》2018,15(5):1113-1122
Speedy running down of forest cover has put great stress on paper industry for finding new fibrous raw materials. Rice straw is an abundantly available lignocellulosic material especially in wood-short countries and can be utilized as an alternate fibre resource by paper mills. Bleaching is a crucial step in papermaking that involves the chemical reactions to reduce the colour of the pulp and makes it brighter for manufacturing writing and printing grade paper. Contrary to this, bleaching results into the formation of toxic, biorefractory and carcinogenic chlorolignin compounds that pose serious health hazards to aquatic life and human beings. A study was carried out using rice straw soda-AQ pulp for bleaching with sequence based on elemental chlorine (CEOPHH). Further, to reduce the wastewater pollution load, emphasis was given on replacement of elemental chlorine with chlorine dioxide at the first bleaching stage (CD10EOPHH CD30EOPHH and CD50EOPHH) and elemental chlorine-free (ECF) bleaching (DEOPD). The study revealed that generation of chlorophenolic compounds was the highest in CEOPHH sequence followed by CD10EOPHH CD30EOPHH and CD50EOPHH, i.e. 6047, 4765, 4247 and 3864 mg/t, respectively. In DEOPD bleaching sequence, the generation of chlorophenolic compounds in wastewater was reduced to 421 mg/t. ECF bleaching had major impacts on reduction in chloroguaiacols (97%) and chlorophenols (92%) that were in the highest quantity in effluents of CEOPHH bleaching sequence. DEOPD bleaching was found to be a promising option for pulp and paper industry for cutting down the generation of chlorophenolic compounds in bleaching effluents. 相似文献