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The presence of noise in measured data should be carefully considered in inverse scattering methodologies, because of the intrinsic ill-conditioning of the problem. To limit the effects of noise on the retrieval procedure, this letter presents an innovative fuzzy-logic-based approach. The proposed strategy allows one to take into account the corrupted nature of the data by fully exploiting all the available information content of the measurements. Selected synthetic and experimental test cases are considered for assessing the effectiveness of the proposed approach also in comparison with a reference inverse scattering technique. 相似文献
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R. Petrini F. Slejko A. Lutman S. Pison G. Franceschini L. Zini F. Italiano A. Galic 《Environmental Earth Sciences》2011,62(3):481-491
High arsenic (As) concentrations, >900 μg/L, were measured in Ca–Mg–SO4 waters from springs and drainages in the village of Pesariis in the Carnic Alps (NE Italy). Oxidation of the outcropping
arsenian marcasite ore deposits of the area is proposed as the mechanism for As release into oxygenated waters during runoff.
Nevertheless, the limited extension of the ore deposit and the relatively low As content of the mineralization suggest that
sulfide weathering might not be the only process responsible for the highest As concentration in groundwaters. An additional
mechanism involves As adsorption onto ferric iron particulate during oxidation, the drawdown in reducing environment at depth
during water infiltration, and the release of ferrous iron and sorbed arsenic to the water columns by reductive dissolution
of hydrous ferric oxides (HFO). This yields the observed Fe–As correlation. Newly formed HFO precipitates when groundwaters
discharge to aerated conditions, leading to the removal of As, which strongly partitions into the iron-rich sediments, adsorbed
onto the surface of amorphous Fe2O3·xH2O. The calculated and measured As concentration in sediments exceeds 10% by weight. Furthermore, geochemical and isotopic
data indicate that the As-rich reservoir partly mixes with shallower aquifers, commonly tapped for drinking supply, representing
a natural hazard for inhabitants. 相似文献
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This paper presents a framework to quantify the overall variability of the model estimations of Total Polychlorinated Biphenyls (Total PCBs) concentrations in the Niagara River on the basis of the uncertainty of few model parameters and the natural variability embedded in some of the model input variables. The results of the uncertainty analysis are used to understand the importance of stochastic model components and their effect on the overall reliability of the model output and to evaluate multiple sources of uncertainty that might need to be further studied. The uncertainty analysis is performed using a newly developed point estimate method, the Modified Rosenblueth method. The water quality along the Niagara River is simulated by coupling two numerical models the Environmental Fluid Dynamic Code (EFDC) – for the hydrodynamic portion of the study and the Water Quality Analysis and Simulation Program (WASP) – for the fate and transport of contaminants. For the monitoring period from May 1995 to March 1997, the inflow Total PCBs concentration from Lake Erie is the stochastic component that most influences the variability of the modeling results for the simulated concentrations at the exit of the Niagara River. Other significant stochastic components in order are as follows: the suspended sediments concentration, the point source loadings and to a minor degree the atmospheric deposition, the flow and the non-point source loadings. Model results that include estimates of uncertainty provide more comprehensive information about the variability of contaminant concentrations, such as confidence intervals, and, in general offer a better approach to compare model results with measured data. 相似文献
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Seb Oliver Robert G. Mann Ruth Carballo Alberto Franceschini Michael Rowan-Robinson Maria Kontizas Anastasios Dapergolas Evanghelos Kontizas Aprajita Verma David Elbaz Gian Luigi Granato Laura Silva Dimitra Rigopoulou J. Ignacio Gonzalez-Serrano Steve Serjeant reas Efstathiou Paul P. van der Werf 《Monthly notices of the Royal Astronomical Society》2002,332(3):536-548
We present results from a deep mid-infrared survey of the Hubble Deep Field South (HDF-S) region performed at 6.7 and 15 μm with the ISOCAM instrument on board the Infrared Space Observatory ( ISO ). The final map in each band was constructed by the co-addition of four independent rasters, registered using bright sources securely detected in all rasters, with the absolute astrometry being defined by a radio source detected at both 6.7 and 15 μm. We sought detections of bright sources in a circular region of radius 2.5 arcmin at the centre of each map, in a manner that simulations indicated would produce highly reliable and complete source catalogues using simple selection criteria. Merging source lists in the two bands yielded a catalogue of 35 distinct sources, which we calibrated photometrically using photospheric models of late-type stars detected in our data. We present extragalactic source count results in both bands, and discuss the constraints that they impose on models of galaxy evolution, given the volume of space sampled by this galaxy population. 相似文献
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Full-vectorial three-dimensional microwave imaging through the iterative multiscaling strategy-a preliminary assessment 总被引：1，自引：0，他引：1
Franceschini G. Franceschini D. Massa A. 《Geoscience and Remote Sensing Letters, IEEE》2005,2(4):428-432
In this letter, a multiscaling strategy for full-vectorial three-dimensional inverse scattering problems is presented. The approach is fully iterative, and it avoids solving any forward problem at each step. Thanks to the adaptive multiresolution model, which offers considerable flexibility for the inclusion of the a priori knowledge and of the knowledge acquired during the iterative steps of the multiscaling process, the overall computational burden as well as the dimension of the search-space is considerably reduced. This allows to balance effectively the tradeoff between computational costs and achievable resolution accuracy. The effectiveness of the proposed approach is demonstrated through a selected set of preliminary experiments using homogeneous dielectric scatterers in a noisy synthetic environment. 相似文献
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