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This study was carried out to assess the distribution of uranium in groundwater by using LED fluorimeter LF-2a and chemical and radiological risks associated with its consumption in Sirsa district, Haryana, India. Uranium concentration ranged between 0.93 and 290μg l-1 with an average value of 49 μg l-1. About 44% of the groundwater samples had uranium concentration above the maximum contamination level of 30 μg l-1 prescribed by the World Health Organization and United States Environmental Protection Agency and 22% of the samples exceeded the permissible limit of 60 μgl-1 prescribed by the Atomic Energy Regulatory Board, India. The average cancer morbidity and mortality risks are determined to be 1.10 × 10-4 and 7.17 × 10-5 respectively, indicating the negligible carcinogenic risk. Hazard quotient for 44% samples is greater than unity which indicates health risk due to chemical toxicity of uranium in groundwater. The associated age-dependent annual effective dose is estimated by taking the prescribed water intake values of different age groups. 相似文献
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W. A. Woodward S. R. Sain H. L. Gray B. Zhao M. D. Fisk 《Pure and Applied Geophysics》2002,159(4):889-903
—?We consider the problem of multivariate outlier testing for purposes of distinguishing seismic signals of underground nuclear events from training samples based on non-nuclear seismic events when certain data are missing. We consider the case in which the training data follow a multivariate normal distribution. Assume a potential outlier is observed on which k features of interest are measured. Assume further that the available training set of n observations on these k features is available but that some of the observations in the training data have missing features. The approach currently used in practice is to perform the outlier testing using a generalized likelihood ratio test procedure based only on the data vectors in the training data with complete data. When there is a substantial amount of missing data within the training set, use of this strategy may lead to a loss of valuable information. An alternative procedure is to incorporate all n of the data vectors in the training data using the EM algorithm to appropriately handle the missing data in the training set. Resampling methods are used to find appropriate critical regions. We use simulation results and analysis of models fit to Pg/Lg ratios for the WMQ station in China to compare these two strategies for dealing with missing data. 相似文献
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This paper demonstrates the applicability of cognitive systems or neural networks in predicting the drillibality of rocks
and wear factor using engineering properties of rocks. Drillability of rocks is a useful guide for evaluating the suitability
of drills for different ground operations. The wear factor of different materials subsequently helps in the selection of proper
drills for different drilling operations. Different rocks were tested for Protodyakonov index, impact strength index, shore
hardness number, Schmidt hammer number, drillability and micro bit chisels for wear factor. The data obtained from the tests
were used to train and test the neural network. Results from the analysis demonstrate that cognitive systems are an effective
tool in the prediction and suitability of drilling operations. Application of these predictive models can be a useful tool
to obtain the value of these important parameters, they can save time and help to avoid the tedious process of instrumentation. 相似文献
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Wiens Ashton Kleiber William Barnhart Katherine R. Sain Dylan 《Mathematical Geosciences》2020,52(4):527-542
Mathematical Geosciences - Two common tasks when processing point cloud data sets are surface estimation and point cloud registration. In this paper, a statistical approach is developed to solve... 相似文献
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Estimating the amount of gas-hydrate and free-gas is difficult in deep seas even with scientific coring and downhole measurements. Well data may be incompatible between holes of a site as well as with depth in the same hole. In this paper, we demonstrate an approach to estimate saturation of gas-hydrate from seismic velocities at any site where data set is limited. The study is carried out in the outer Blake Ridge, which is one of the most intensively studied regions of natural gas-hydrate occurrences and a very distinctive example of studying geophysical signatures of gas-hydrate and free-gas in deep marine sediments. Although, downhole measurements from both vertical seismic profiles (VSPs) and sonic logs provide the most accurate and direct measurements of velocity, only VSP velocities at Ocean Drilling Program (ODP) Sites 994, 995, and 997 on the Blake Ridge are used to estimate the saturation of gas-hydrate and free-gas as sonic logs at ODP sites are not reliable. Here we derive a general trend of the background velocity with depth using the porosity and mineralogy from coring at discrete depth intervals. Saturations of gas-hydrate and free-gas are then estimated from this background velocity using the effective medium modeling. The porosity and mineralogical compositions are taken from four different depths at Site 995, as data quality is the best in this hole. Average saturations of gas-hydrate and free-gas at three holes are estimated as 10–14 and 2–3%, respectively. 相似文献
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Radon filters are often used for removal of multiple reflections from normal move-out-corrected seismic reflection data. In the conventional Radon transform, integration surfaces are hyperbolic rather than linear. This specific hyperbolic surface is equivalent to a parabola in terms of computational expense, but more accurately distinguishes multiples from primary reflections. The forward transform separates seismic arrivals by their differences in travel time move-out. Multiples can be suppressed by an inverse transform of the seismic data. Examples show that multiples are effectively attenuated in pre-stack and stacked seismograms. Based on the parabolic Radon transform, a new method is utilized for missing offset restoration, resampling and regularization of pre-stack individual common depth point (CDP) gathers. The method is also valid for resampling spatially aliased seismic data. Restoration of missing offsets and trace interpolation is an interesting and important problem in seismic data processing. Here we present an application of Radon transform on a multichannel seismic data set from the western continental margin of India (WCMI), which shows remarkable signal enhancement. 相似文献
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Uma Shankar Kalachand Sain Michael Riedel 《Journal of the Geological Society of India》2012,79(2):199-209
The passive eastern Indian margin is rich in gas hydrates, as inferred from the wide-spread occurrences of bottom-simulating
reflectors (BSRs) and recovery of gas hydrate samples from various sites in the Krishna Godavari (KG) and Mahanadi (MN) basins
drilled by the Expedition 01 of the Indian National Gas Hydrate Program (NGHP). The BSRs are often interpreted to mark the
thermally controlled base of gas hydrate stability zone (BGHSZ). Most of the BSRs exhibit moderate to typically higher amplitudes
than those from other seismic reflectors. We estimate the average geothermal gradient of ∼40°C/km and heat flow varying from
23 to 62 mW/m2 in the study area utilizing the BSR’s observed on seismic sections. Further we provide the BGHSZ where the BSR is not continuous
or disturbed by local tectonics or hidden by sedimentation patterns parallel to the seafloor with a view to understand the
nature of BSR. 相似文献