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Yalchin Efendiev Akhil Datta-Gupta Xianlin Ma Bani Mallick 《Mathematical Geosciences》2008,40(2):213-232
In this paper, the Markov Chain Monte Carlo (MCMC) approach is used for sampling of the permeability field conditioned on
the dynamic data. The novelty of the approach consists of using an approximation of the dynamic data based on streamline computations.
The simulations using the streamline approach allows us to obtain analytical approximations in the small neighborhood of the
previously computed dynamic data. Using this approximation, we employ a two-stage MCMC approach. In the first stage, the approximation
of the dynamic data is used to modify the instrumental proposal distribution. The obtained chain correctly samples from the
posterior distribution; the modified Markov chain converges to a steady state corresponding to the posterior distribution.
Moreover, this approximation increases the acceptance rate, and reduces the computational time required for MCMC sampling.
Numerical results are presented. 相似文献
2.
Bani Pramanik 《Pure and Applied Geophysics》1972,93(1):60-67
Summary In this note displacement of a thin perfectly conducting viscoelastic plate of Reiss type in contact with vacuum on both sides and in a uniform magnetic field has been discussed. The plate has been assumed to be acted on by an impulsive load. Solutions have been obtained for small and large values of time. Results have also been discussed for some particular cases. 相似文献
3.
Modeling aggregated expertise of user contributions to assess the credibility of OpenStreetMap features 总被引：1，自引：0，他引：1 
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下载免费PDF全文 The emergence of volunteered geographic information (VGI) during the past decade has fueled a wide range of research and applications. The assessment of VGI quality and fitness‐of‐use is still a challenge because of the non‐standardized and crowdsourced data collection process, as well as the unknown skill and motivation of the contributors. However, the frequent approach of assessing VGI quality against external data sources using ISO quality standard measures is problematic because of a frequent lack of available external (reference) data, and because for certain types of features, VGI might be more up‐to‐date than the reference data. Therefore, a VGI‐intrinsic measure of quality is highly desirable. This study proposes such an intrinsic measure of quality by developing the concept of aggregated expertise based on the characteristics of a feature's contributors. The article further operationalizes this concept and examines its feasibility through a case study using OpenStreetMap (OSM). The comparison of model OSM feature quality with information from a field survey demonstrates the successful implementation of this novel approach. 相似文献
4.
Philipson Bani Clive Oppenheimer Johan C. Varekamp Thomas Quinou Michel Lardy Simon Carn 《Journal of Volcanology and Geothermal Research》2009
Ambae (also known as Aoba), is a 38 × 16 km2 lozenge-shaped island volcano with a coastal population of around 10 000. At the summit of the volcano is lake Voui — one of the largest active crater lakes worldwide, with 40 × 106 m3 of acidic water perched 1400 m a.s.l. After more than 300 years of dormancy, Ambae volcano reawakened with phreatic eruptions through Voui in 1995, and culminating in a series of surtseyan eruptions in 2005, followed by a rapid and spectacular colour change of the lake from light blue to red in 2006. Integrating lake water chemistry with new measurements of SO2 emissions from the volcano during the 2005–2006 eruptive period helps to explain the unusual and spectacular volcanic activity of Ambae — initially, a degassed magma approached the lake bed and triggered the surtseyan eruption. Depressurization of the conduit facilitated ascent of volatile-rich magma from the deeper plumbing system. The construction of a cone during eruption and the high degassing destabilised the equilibrium of lake stratification leading to a limnic event and subsequently the spectacular colour change. 相似文献
5.
R. Rooki F. Doulati Ardejani A. Aryafar A. Bani Asadi 《Environmental Earth Sciences》2011,64(5):1303-1316
Water is one of the basic and fundamental requirements for the survival of human beings. Mining of the sulphide mines usually
produce a significant amount of acid mine drainage (AMD) contributing to huge amounts of chemical components and heavy metals
in the receiving waters. Prediction of the heavy metals in the AMD is important in developing any appropriate remediation
strategy. This paper attempts to predict heavy metals (Cu, Fe, Mn, Zn) from the AMD using backpropagation neural network (BPNN),
general regression neural network (GRNN) and multiple linear regression (MLR), by taking pH, sulphate (SO4) and magnesium (Mg) concentrations in the AMD into account in Shur River, Sarcheshmeh porphyry copper deposit, southeast
Iran. The comparison between the predicted concentrations and the measured data resulted in the correlation coefficients,
R, 0.92, 0.22, 0.92 and 0.92 for Cu, Fe, Mn and Zn ions using BPNN method. Moreover, the R values were 0.89, 0.37, 0.9 and 0.91 for Cu, Fe, Mn, and Zn taking the GRNN method into consideration. However, the correlation
coefficients were low for the results predicted by MLR method (0.83, 0.14, 0.9 and 0.85 for Cu, Fe, Mn and Zn ions, respectively).
The results further indicate that the ANN can be used as a viable method to rapidly and cost-effectively predict heavy metals
in the AMD. The results obtained from this paper can be considered as an easy and cost-effective method to monitor groundwater
and surface water affected by AMD. 相似文献
6.
Yalchin Efendiev Akhil Datta-Gupta Xianlin Ma Bani Mallick 《Mathematical Geology》2006,38(8):1031-1035
7.
Philipson Bani Clive Oppenheimer Vitchko I. Tsanev Simon A. Carn Shane J. Cronin Rachel Crimp Julie A. Calkins Douglas Charley Michel Lardy Tjarda R. Roberts 《Bulletin of Volcanology》2009,71(10):1159-1168
Volcanoes provide important contributions to atmospheric budgets of SO2 and reactive halogens, which play significant roles in atmospheric oxidative capacity and radiation. However, the global
source strengths of volcanic emissions remain poorly constrained. These uncertainties are highlighted here by the first measurements
of gas emission rates from Ambrym volcano, Vanuatu. Our initial airborne ultraviolet spectroscopic measurements made in January
2005 indicate fluxes of 18–270 kg s-1 of SO2, and 62–110 g s-1 of BrO, into the atmosphere, placing Ambrym amongst the largest known contemporary point sources of both these species on
Earth. We also estimate high Cl and F fluxes of ~8–14 and ~27–50 kg s-1, respectively, for this period. Further observations using both airborne and spaceborne remote sensing reveal a fluctuating
SO2 output between 2004 and 2008, with a surge in the first half of 2005, and underline the substantial contribution that a single
passively degassing volcano can make to the atmospheric budget of sulfur and halogens. 相似文献
8.
Vibration mitigation using smart, reliable and cost‐effective mechanisms that requires small activation power is the primary objective of this paper. A semi‐active controller‐based neural network for base‐isolation structure equipped with a magnetorheological (MR) damper is presented and evaluated. An inverse neural network model (INV‐MR) is constructed to replicate the inverse dynamics of the MR damper. Next, linear quadratic Gaussian (LQG) controller is designed to produce the optimal control force. Thereafter, the LQG controller and the INV‐MR models are linked to control the structure. The coupled LQG and INV‐MR system was used to train a semi‐active neuro‐controller, designated as SA‐NC, which produces the necessary control voltage that actuates the MR damper. To evaluate the proposed method, the SA‐NC is compared to passive lead–rubber bearing isolation systems (LRBs). Results revealed that the SA‐NC was quite effective in seismic response reduction for wide range of motions from moderate to severe seismic events compared to the passive systems. In addition, the semi‐active MR damper enjoys many desirable features, such as its inherent stability, practicality and small power requirements. The effectiveness of the SA‐NC is illustrated and verified using simulated response of a six‐degree‐of‐freedom model of a base‐isolated building excited by several historical earthquake records. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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