a robust linear quantitative structure-property relationship (qspr) model has been constructed to model and predict the refractivity indices of 101 organic compounds as common halo-derivatives of normal paraffin by application of the structural descriptors combined with multiple linear regression (mlr) method. in the main part of this study, theoretical molecular descriptors were adopted from t...

High accuracy of impact height is important to get reliable Radio Occultation (RO) measurements of the atmosphere refractivity. We have made an investigation on how accurately we can measure the impact height at ground level using wave optics simulations, realistic refractivity profiles, a realistic simulator for an advanced RO instrument including noise, and using phase matching for the invers...

Tomographic techniques are successfully applied to obtain 4D images of the tropospheric refractivity in a local dense network. In the lower atmosphere both the small height and time scales and the non-dispersive nature of tropospheric delays require a more careful analysis of the data. We show how GPS data is processed to obtain the tropospheric slant delays using the GIPSY-OASIS II software an...

Calculation of a stellar occultation lightcurve from an assumed refractivity profile involves the integral of the refractivity or its derivatives along the line of sight through an atmosphere. For the general case, normal numerical integration can be time consuming for least-squares fitting with a modest number of free parameters, or for calculation at a fine grid for comparison with local refo...

In this study, we propose a model for predicting atmospheric refractivity using meteorological data and deep learning. The purpose of study is to compare the prediction accuracy traditional interpolation methods proposed model, verify whether learning trained on can provide values closer true values, thus demonstrate potential utilizing in refractivity.

Gold-deposited optical fiber sensors with film thicknesses from 30 to 60 nm were prepared, and the responses to a wide range of a refractivity (1.33-1.54 refractive index (RI) units) were investigated both experimentally and theoretically. The response curve of the sensor has two minima in the refractivity range from 1.33 to 1.44 and at 1.462 RI units. The former minimum is due to surface plasm...

In this paper, we present a new estimation of the atmospheric refractivity profile combining the scattering signal (electromagnetic wave propagation loss) and the direct signal (phase delay). The refractivity profile is modeled using four parameters, i.e., the gradient of the refractivity profile (c1, c2) and the vertical altitude (h1, h2). We apply the NSGA-II (Non-dominated Sorting Genetic Al...

Radio wave propagation on low-altitude paths over the ocean above 2GHz is significantly affected by negative refractivity gradients in the atmospheric surface layer, which form what is often referred to as an evaporation duct (ED). Refractivity from clutter (RFC) is an inversion approach for the estimation of the refractivity profile from radar clutter, and RFC-ED refers to its implementation f...

[1] Refractivity from clutter (RFC) retrieves the radio frequency refractive conditions along a propagation path by inverting the measured radar sea clutter return. In this paper, a real-time RFC technique is proposed called ‘‘Improved Best Fit’’ (IBF). It is based on finding the environment with best fit to one of many precomputed, modeled radar returns for different environments in a database...

Validation studies of current GPS radio occultation experiments using meteorological analyses consistently report on a negative refractivity bias in the lower troposphere. It is shown that refractivity profiles obtained from Doppler-inverted bending angle profiles not only deviate significantly within zones of multipath propagation but also depend on the selected end point of the occultation si...