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81.
The separation features of the floatex density separator (FDS) are investigated through experimental and computational approaches. It has been shown that the performance of the FDS can be predicted reasonably well using a slip velocity model and steady-state mass balance equations. The approach for the formulation of the slip velocity model makes a difference in the prediction of FDS performance. The computed data from four different slip velocity models have been compared and contrasted with the experimental observations. It has been shown that a slip velocity model based on the modified Richardson and Zaki equation, in which the dissipative pressure gradient is considered to be the primary driving force for separation, predicts the performance more accurately than the other three. A deslimed feed is recommended for better performance of the FDS. 相似文献
82.
Textural identification of basaltic rock mass using image processing and neural network 总被引:3,自引:0,他引:3
Naresh Singh T. N. Singh Avyaktanand Tiwary Kripa M. Sarkar 《Computational Geosciences》2010,14(2):301-310
A new approach to identify the texture based on image processing of thin sections of different basalt rock samples is proposed
here. This methodology uses RGB or grayscale image of thin section of rock sample as an input and extracts 27 numerical parameters.
A multilayer perceptron neural network takes as input these parameters and provides, as output, the estimated class of texture
of rock. For this purpose, we have use 300 different thin sections and extract 27 parameters from each one to train the neural
network, which identifies the texture of input image according to previously defined classification. To test the methodology,
90 images (30 in each section) from different thin sections of different areas are used. This methodology has shown 92.22%
accuracy to automatically identify the textures of basaltic rock using digitized image of thin sections of 140 rock samples.
Therefore, present technique is further promising in geosciences and can be used to identify the texture of rock fast and
accurate. 相似文献
83.
Santanu Banerjee S.K. Bhattacharya Subir Sarkar 《Journal of Asian Earth Sciences》2007,29(5-6):823-831
Variations of carbon and oxygen isotopic ratios in response to cyclical sea level fluctuations have been documented from a Paleoproterozoic peritidal stromatolite succession. The upper division of the Kajrahat Limestone, Vindhyan Supergroup of central India consists of several shallowing upward stromatolite cycles identified by regular and systematic changes in stromatolite size. Normally, larger stromatolites are followed upward in the succession by smaller stromatolites and microbial laminites that occupy the top of the cycle. Desiccation cracks are found in all the facies indicating subaerial exposure. We investigated the stable isotope compositional variations across nine complete stromatolite cycles showing frequent subaerial emergence. Carbon and oxygen isotopic values of the limestones, in general, are comparable to contemporary marine values available from earlier studies but show regular depletion in response to shallowing of the water level. The δ13C and δ18O values of the limestones vary within an individual stromatolite cycle; depleted values characterize the topmost part of the cycles. The isotope pattern is explained by micritic carbonate deposition in different sub environments of the shallow marine domain having different salinity and variable duration of exposure. These variations also probably caused the observed scatter in δ13C and δ18O values of supratidal microbial laminites. 相似文献
84.
In an experiment on methane-emission measurements from rice fields amended with urea, biogas spent slurry (BSS) + urea, and farm yard manure (FYM) + urea, three distinctive peaks in the methane emissions were observed at 15, 46, and 69 days after transplanting (DAT) due to the availability of readily degradable C-sources. In all cases, the highest peak was at 69 DAT. The steepest Eh drop to a minimum of -320 mV was reached within two weeks of submergence. pH ranged between 7.5 and 8.5. The combined fertilization (FYM + urea) plot showed the maximum emission rate of 4.86 mg m–2 h–1 with a total load of 49.44 kg ha–1 and was 2.3 times higher than (BSS + urea)-treated plot (22.08 kg ha–1). Grain yields in urea, (BSS + urea) and (FYM + urea) plots were 3.34, 2.94, and 2.85 t ha–1 respectively, suggesting that biogas slurry is a preferred source over FYM causing lesser environmental pollution without any significant reduction in grain yield. 相似文献
85.
Raj Kumar Suchandra A. Bhowmick Sulagna Ray Vihang Bhatt Suhe Surendran Sujit Basu Abhijit Sarkar Vijay K. Agarwal 《Natural Hazards》2009,49(2):275-291
Accurate prediction of ocean surface waves is a challenging task with many associated difficulties. Availability of good quality
wind and wave information from satellite platforms inspired the scientific community to assimilate such data in various spectral
wave models for enhancing the accuracy of prediction. Over the Indian Ocean, which is the region of interest for the present
study, wave heights in extreme situation can go up to 12–14 m, thereby increasing the probability of coastal hazards. This
region is further governed by the southern ocean swells that propagate thousands of kilometers. These are, in general, not
well captured by the spectral wave models. Therefore, assimilation of altimeter data in open ocean wave model WAM has been
attempted with the aim of enhancing the quality of prediction of significant wave height. Further, simulated wave spectra
have been assimilated in a coastal wave model SWAN. This assimilation has been found to significantly improve the prediction
of the height of wind waves as well as swell waves.
V. Bhatt and S. Surendran are former students of Meteorology and Oceanography Group, Space Applications Centre, ISRO, Ahmedabad. 相似文献
86.
An approach for GIS-based statistical landslide susceptibility zonation—with a case study in the Himalayas 总被引:14,自引:1,他引:14
Ashis K. Saha Ravi P. Gupta Irene Sarkar Manoj K. Arora Elmar Csaplovics 《Landslides》2005,2(1):61-69
Landslide susceptibility zonation (LSZ) is necessary for disaster management and planning development activities in mountainous regions. A number of methods, viz. landslide distribution, qualitative, statistical and distribution-free analyses have been used for the LSZ studies and they are again briefly reviewed here. In this work, two methods, the Information Value (InfoVal) and the Landslide Nominal Susceptibility Factor (LNSF) methods that are based on bivariate statistical analysis have been applied for LSZ mapping in a part of the Himalayas. Relevant thematic maps representing various factors (e.g., slope, aspect, relative relief, lithology, buffer zones along thrusts, faults and lineaments, drainage density and landcover) that are related to landslide activity, have been generated using remote sensing and GIS techniques. The LSZ derived from the LNSF method, has been compared with that produced from the InfoVal method and the result shows a more realistic LSZ map from the LNSF method which appears to conform to the heterogeneity of the terrain. 相似文献
87.
The Curie depth map of India compiled from MAGSAT data has been used for preparing the lithosphere thickness and the surface
heat flow density maps of the Indian Craton, utilizing the concept of magnetothermometry. The lithosphere thicknesses of the
major Indian geological units/provinces, as obtained from the prepared map, are found to be in reasonably good agreement with
the previously published values for these regions. Also, the surface heat flow density values obtained from the prepared maps
closely follow the previously published results. The maps are useful in providing first order estimates of lithosphere thickness
and surface heat flow density of the important geological units/provinces of India. 相似文献
88.
A two-dimensional numerical model is employed to study the effect of the coastal urban heat island on the sea breeze front
and the thermal internal boundary layer height. The temperature at the land surface is determined by solving an energy budget
equation. The effect of the urban heat island is studied by varying the width of the region and its intensity. During the
early afternoon, the presence of the urban heat island enhances the strength of convergence of the sea breeze front and also
reduces its inland penetration. The presence of the urban heat island causes increased thermal internal boundary layer height.
Larger urban width causes larger vertical velocity and higher thermal internal boundary layer. Stronger convergence and higher
thermal internal boundary layer are also obtained in case of larger heat island intensity. 相似文献
89.
90.