Elicited Data and Incorporation of Expert Opinion for Statistical Inference in Spatial Studies     

Subhash R. Lele  Abhik Das 《Mathematical Geology》2000,32(4):465-487

Spatial data are often sparse by nature. However, in many instances, information may exist in the form of soft data, such as expert opinion. Scientists in the field often have a good understanding of the phenomenon under study and may be able to provide valuable information on its likely behavior. It is thus useful to have a sensible mechanism that incorporates expert opinion in inference. The Bayesian paradigm suffers from an inherent subjectivity that is unacceptable to many scientists. Aside from this philosophical problem, elicitation of prior distributions is a difficult task. Moreover, an intentionally misleading expert can have substantial influence on Bayesian inference. In our experience, eliciting data is much more natural to the experts than eliciting prior distributions on the parameters of a probability model that is a purely statistical construct. In this paper we elicit data, i.e., guess values for the realization of the process, from the experts. Utilizing a hierarchical modeling framework, we combine elicited data and actual observed data for inferential purposes. A distinguishing feature of this approach is that even an intentionally misleading expert proves to be useful. Theoretical results and simulations illustrate that incorporating expert opinion via elicited data substantially improves the estimation, prediction, and design aspects of statistical inference for spatial data.  相似文献   

Economics of the coal industry east of the Mississippi, 1973–1982     

Subhash B. Bhagwat 《International Journal of Coal Geology》1987,8(4)

Government regulations on health, safety and environment have been poppular blamed for the declining productivity in U.S. coal mines since 1970. The stagnation in the coal industry east of the Mississippi is alleged to have been caused by this declining productivity and by the growth of cheaper and cleaner coal production west of the Mississippi. Economic evidence suggests, however, that productivity declines were more due to a relative lowering of labor costs in comparison with coal prices and due to work stoppages. The development of western coals fields was spurred by growth in local demand and had only a relatively small impact on coal production east of the Mississippi. Problems of the eastern coal industry are rooted mainly in slow economic growth in eastern U.S. which must be addressed in the long-term interests of the eastern coal industry.  相似文献   

A gradational density model for gravity anomalies over oceanic ridges     

Subhash C. Garde 《Physics of the Earth and Planetary Interiors》1974,8(1):46-52

The long-wavelength gravity anomalies observed over oceanic ridges have been interpreted in terms of horizontal slabs with lateral variation of density. The location of such a slab in the earth's interior is estimated to be between the depths of 350 and 430 km, which defines the boundaries of the upper phase-transition zone of the mantle. A total density contrast, between the end planes of the horizontal slab, of 0.3 g/cm³ appears to be satisfactory for the interpretation. This remarkable coincidence in depth and density contrast associated with the pyroxene-garnet transformation process is considered to suggest that this process may possibly be: (1) taking place laterally; and (2) generating the gradational density contact which is reflected in the gravity anomalies. In turn, the mechanism for this lateral phase transformation may ultimately be attributable to the convection currents in the asthenosphere.  相似文献   

Disturbance produced in an elastic half-space by impulsive normal pressure     

Subhash Chandra Ghosh 《Pure and Applied Geophysics》1970,80(1):71-83

Summary The displacement produced in the half-space by uniform impulsive pressure acting over a circular portion of the surface has been obtained in terms of definite integrals. FollowingCagniard andGarvin, the displacement at an interior point on the axis of symmetry has been calculated. The approximate displacement at points far off from the axis of symmetry has been obtained by using saddle point method and Tauberian limit theorem.  相似文献   

Major ion chemistry and quality assessment of the groundwater resources of Nanded tehsil,a part of southeast Deccan Volcanic Province,Maharashtra, India     

Vasant Madhav Wagh  Dipak Baburao Panaskar  Abhay Mukund Varade  Shrikant Vitthal Mukate  Satyajit Kundlik Gaikwad  Ranjitsinh Subhash Pawar  Aniket Avinash Muley  Manesh Laxman Aamalawar 《Environmental Earth Sciences》2016,75(21):1418

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On a model simulating lack of hydraulic connection between a man-made reservoir and the volume of poroelastic rock hosting the focus of a post-impoundment earthquake     

Ramesh Chander  S K Tomar 《Journal of Earth System Science》2016,125(8):1543-1555

The idea that a direct hydraulic connection between a man-made reservoir and the foci of post-impoundment earthquakes may not exist at all sites is eminently credible on geological grounds. Our aim is to provide a simple earth model and related theory for use during investigations of earthquakes near new man-made reservoirs. We consider a uniform circular reservoir which rests on the top surface of a no-hydraulic-connection earth model (NHCEM). The model comprises a top elastic (E) layer, an intermediate poroelastic (P) layer, and a bottom elastic half space. The focus of a potential earthquake in the P layer is located directly under the reservoir. The E layer disrupts the hydraulic connection between the reservoir and the focus. Depth of water in the reservoir varies as H ^′ + hcos(ω t). Expressions for reservoir-induced stresses and pore pressure in different layers of the NHCEM are obtained by solving the boundary-value problem invoking full coupling between mean normal stress and pore pressure in the P layer. As an application of the derived mathematical results, we have examined and found that earthquakes on 60^° normal faults may occur in the P-layer of a selected NHCEM at epochs of low reservoir level if the reservoir lies mostly in the footwall of the fault. The exercise was motivated by observations of such earthquakes under the man-made Lake Mead after it was impounded.  相似文献   

A simulation of earthquake induced undrained pore pressure changes with bearing on some soil liquefaction observations following the 2001 Bhuj earthquake     

Sarkar  Irene  Chander  Ramesh 《Journal of Earth System Science》2003,112(3):471-477

The Bhuj earthquake of January 26th, 2001, induced wide spread liquefaction within the Kachch peninsula. It has been pointed out that inundation due to soil liquefaction was short lived in some parts than in others in the affected region. Several geological, seismological and hydrological factors would have cumulatively contributed to these observed changes. We simulate in this article, undrained or short-term change in pore pressure in a poroelastic half space, in response to a simplified model of the Bhuj earthquake source. We find that the regions of relatively shorter lived inundation due to soil liquefaction may fall in the region where pore pressure responsible for soil liquefaction attributable to strong ground shaking was counteracted by pore pressure changes due to undrained poroelastic effect and vice versa.  相似文献   

Study of Distribution and Asymmetry in Soft X-ray Flares over Solar Cycles 21–24     

Amrita Prasad  Roy  Soumya  Panja  Subhash Chandra  Patra  Sankar Narayan 《Geomagnetism and Aeronomy》2022,62(3):288-304

Geomagnetism and Aeronomy - This paper investigates the North–South (N–S) as well as East–West (E–W) distribution and asymmetry in Soft X-ray flares (SXR) activity during...  相似文献   

Characterization and evaluation of processes governing the groundwater quality in parts of the Sabarmati basin,Gujarat using hydrochemistry integrated with GIS   总被引：1，自引：0，他引：1  

Kumari Rina  P. S. Datta  Chander Kumar Singh  Saumitra Mukherjee 《水文研究》2012,26(10):1538-1551

Intense agricultural and industrial activities in any area are likely to make groundwater vulnerable with respect to its quality. In one such area which is a part of Sabarmati river basin of Gujarat, factors influencing the groundwater hydrochemistry in pre‐ and post‐monsoon season were evaluated. Groundwater samples were collected from 5 km × 5 km grids on the basis of spectral signature of vegetation and soil, observed on satellite image. Integration of Conventional graphical plots, Piper plot, saturation index values (estimated using PHREEQC) and GIS was helpful not only to create the database for analysis of spatial variation in respective water quality parameters but also to decipher the hydrogeochemical process occurring in such a large area. USSL diagram and % sodium were used to characterise the suitability of groundwater for irrigation. It was observed that leaching of wastes disposed from anthropogenic activities and agrichemicals is the major factor influencing the groundwater quality, in addition to the natural processes such as weathering, dissolution and ion exchange. Sea water relics are also impacting the groundwater quality. Control of indiscriminate and unplanned exploitation of groundwater, application of fertilizers and disposal of industrial wastes in the affected areas can possibly ensure groundwater protection from further pollution and depletion. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

A Search for Periodicities in F10.7 Solar Radio Flux Data     

Roy  Soumya  Prasad  Amrita  Panja  Subhash Chandra  Ghosh  Koushik  Patra  Sankar Narayan 《Solar System Research》2019,53(3):224-232

The radio frequency emission at 10.7 cm (or 2800 MHz) wavelength (considered as solar flux density) out of different possible wavelengths is usually selected to identify periodicities because of its high correlation with solar extreme ultraviolet radiation as well as its complete and long observational record other than sunspot related indices. The solar radio flux at 10.7 cm wavelength plays a very valuable role for forecasting the space weather because it is originated from lower corona and chromospheres region of the Sun. Also, solar radio flux is a magnificent indicator of major solar activity. Here in the present work the solar radio flux data from 1965 to 2014 observed at the Domimion Radio Astrophysical Observatory in Penticton, British Columbiahas been processed using Date Compensated Discrete Fourier Transform (DCDFT) to identify predominant periods within the data along with their confidence levels. Also, the multi-taper method (MTM) for periodicity analysis is used to validate the observed periods. Present investigation exhibits multiperiodicity of the time series F10.7 solar radio flux data around 27, 57, 78, 127, 157, 4096 days etc. The observed periods are also compared with the periods of MgII Index data using same algorithm as MgII Index data has 99.9% correlation with F10.7 Solar Radio Flux data. It can be observed that the MgII index data exhibits similar periodicities with very high confidence levels.Present investigation also clearly indicates that the computed results are very much confining with the results obtained in different communication for the similar data of 10.7 cm Solar Radio Flux as well as for the other solar activities.

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