275 research outputs found
Application of the principle and unbiased predictive risk estimator for determining the regularization parameter in 3D focusing gravity inversion
The principle and the unbiased predictive risk estimator are used to
determine optimal regularization parameters in the context of 3D focusing
gravity inversion with the minimum support stabilizer. At each iteration of the
focusing inversion the minimum support stabilizer is determined and then the
fidelity term is updated using the standard form transformation. Solution of
the resulting Tikhonov functional is found efficiently using the singular value
decomposition of the transformed model matrix, which also provides for
efficient determination of the updated regularization parameter each step.
Experimental 3D simulations using synthetic data of a dipping dike and a cube
anomaly demonstrate that both parameter estimation techniques outperform the
Morozov discrepancy principle for determining the regularization parameter.
Smaller relative errors of the reconstructed models are obtained with fewer
iterations. Data acquired over the Gotvand dam site in the south-west of Iran
are used to validate use of the methods for inversion of practical data and
provide good estimates of anomalous structures within the subsurface
Automatic estimation of the regularization parameter in 2-D focusing gravity inversion: an application to the Safo manganese mine in northwest of Iran
We investigate the use of Tikhonov regularization with the minimum support
stabilizer for underdetermined 2-D inversion of gravity data. This stabilizer
produces models with non-smooth properties which is useful for identifying
geologic structures with sharp boundaries. A very important aspect of using
Tikhonov regularization is the choice of the regularization parameter that
controls the trade off between the data fidelity and the stabilizing
functional. The L-curve and generalized cross validation techniques, which only
require the relative sizes of the uncertainties in the observations are
considered. Both criteria are applied in an iterative process for which at each
iteration a value for regularization parameter is estimated. Suitable values
for the regularization parameter are successfully determined in both cases for
synthetic but practically relevant examples. Whenever the geologic situation
permits, it is easier and more efficient to model the subsurface with a 2-D
algorithm, rather than to apply a full 3-D approach. Then, because the problem
is not large it is appropriate to use the generalized singular value
decomposition for solving the problem efficiently. The method is applied on a
profile of gravity data acquired over the Safo mining camp in Maku-Iran, which
is well known for manganese ores. The presented results demonstrate success in
reconstructing the geometry and density distribution of the subsurface source
Determinant criteria for designing Health benefit package in selected countries
Health benefit package described as primary health interventions that provided with government using general funds for all regardless their financial ability. This study was aimed at determine appropriate pattern for Iran using comparative survey of Health benefit package in various countries. A review exploration was done, scholars was selected population of both developed and developing countries, required information was also extracted by articles, searches and reports of reliable sources and date were analyzed by SPSS, in brief. The vast majority frequencies was respectively allocated to accessibility (40.7%), cost- effectiveness (29.6%), prioritize, efficacy and cost (22.2%). most countries located in WHO African region were selected cost-effectiveness and accessibility, WHO southeast Asia region were selected, coverage, prioritize, efficacy and quality and finally most WHO Europeans region were elected effectiveness and services costs for including services in Health benefit package. According to most Health benefit package designer emphasis on criteria including accessibility and costeffectiveness, to design Health benefit package for Iran, these criteria must be noticed
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