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Unquestionably, current density pseudo-section derived from in-phase very low frequency (VLF) data, developed by Karous and Hjelt, has been one of the most popular preliminary schemes for the interpretation of VLF data due to its straightforwardness and applicability. In practice, however, the Karous and Hjelt filtering method does not behave accurately and has some weaknesses: (i) the depth estimation is erratic, even in shallow cases, (ii) to a far lesser extent, the horizontal estimation is inaccurate, in particular when the sources interfere with each other, and (iii) under circumstances where multiple bodies are in close proximity, spurious artifacts appear. These factors could be misleading and result in a wrong interpretation. Changing the Biot–Savart law into a linear equation and employing inverse theory in this paper, the precision of spatial estimations, in the case of superficial objects, becomes far more precise. More importantly, independent of the number of neighboring targets and their closeness, no spurious artifacts are observed. This methodology is tested on synthetic isolated and interfering various models with different sizes, depths, shapes and resistivities. It is also applied to real data over the 'Ghoori Ghale' cave in the vicinity of Kermanshah, Iran, and its satisfying and noteworthy solutions are compared with the Karous and Hjelt method. [ABSTRACT FROM AUTHOR]

Tunable optical properties of silver-dielectric-silver nanoshell including surface plasmon resonance (SPR) and resonance light scattering (RLS) based on quasi-static theory are investigated. When the silver core radius increases, the longer resonance wavelength red shifts and light scattering cross-section decreases whereas the shorter resonance wavelength blue shifts and the light scattering cross-section increases. The effect of middle dielectric thickness on the light scattering cross-section of nanoshell is different from those of the silver core radius changes. As middle dielectric radius increases, the longer resonance wavelength first blue shifts and then red shifts and the light scattering cross-section increases whereas the shorter resonance wavelength always red shifts and the light scattering cross-section decreases. The sensitivity of RLS to the refractive index of embedding medium is also reported. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness leads to increase the sensitivity of silver-dielectric-silver nanoshell. Tunable optical properties of silver-dielectric-silver nanoshell verify the biosensing potential of this nanostructure. [ABSTRACT FROM AUTHOR]

In this paper, light absorption spectra properties of a bimetal multilayer nanoshell based on quasistatic approach are investigated. Comparing with silver-dielectric-silver and silver-dielectric-gold nanoshells, gold-dielectric-silver nanoshells have three intense and separated plasmon peaks which are more suitable for multiplex biosensing. Calculations show that relatively small thickness of outer silver shell and large dielectric constant of middle dielectric layer of gold-dielectric-silver nanoshell are suitable to obtain the triple plasmon resonance. [ABSTRACT FROM AUTHOR]

In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell. [ABSTRACT FROM AUTHOR]

The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together. [ABSTRACT FROM AUTHOR]

• Electromagnetic induction methods were used to characterize soil drainage classes. • Inversion method was applied on apparent MS data measured by EM38. • Soil MS, derived from EMI methods highly estimates MS derived from lab measurements. • Using EMI instruments provides fast and cost efficient drainage investigations. As a physical property of soil, magnetic susceptibility (MS) has been widely used to delineate soil drainage conditions over the past two decades, where all MS values were derived from laboratory measurements. In this paper, the ability of an electromagnetic induction (EMI) instrument, Geonics EM38, in in-field measurements of apparent magnetic susceptibility (MS a or κ a) of topsoil was tested on six selected soil profiles having different drainage conditions. The MS a data, measured in both vertical and horizontal coil configurations of EM38, were then inverted using an iterative 1-D inversion procedure to calculate real volume MS of soil layers up to 1 m depth. Moreover, volume and mass-specific MS of the soil profiles were directly measured in laboratory by employing Bartington MS2C and MS2B sensors applied on core and dried soil samples, respectively, collected at the soil profiles. Comparing the results revealed that volume MS profiles derived from inversion of MS a data were positively correlated with MS profiles measured in laboratory, especially at topsoil. It was also found that MS values in poorly drained soil profile were lower than those of a well-drained profile. So, considering that EMI methods are fast, precise and cost-efficient, they would be preferred over conventional methods for delineating soil drainage conditions if using soil MS assessment is considered as soil drainage criteria. [ABSTRACT FROM AUTHOR]