An analysis about the backscattering characteristics of a metamaterial coated magnetodielectric sphere covered with a metasurface has been presented. The effects of various types of metamaterial coatings and surface reactances of lossless metasurface upon the backscattering cross-section of a metamaterial coated magnetodielectric sphere covered with a metasurface have been studied. It is shown that the negligible backscattering cross-section from a double near-zero metamaterial coated magnetodielectric sphere can be enhanced significantly by using specific types of lossless metasurfaces. These types of enhanced backscattering cross-section find applications in the radar detection problems. The proposed theory is also extended to the lossy double negative metamaterial coated magnetodielectric sphere covered with a lossless metasurface. During the study, it is found that for a specific part of the lossy double negative metamaterial bandwidth, two specific types of lossless metasurfaces can be used to reduce the backscattering cross-section as compared to the backscattering cross-section of a lossy double negative metamaterial coated magnetodielectric sphere without metasurface.

In this article, we provide a numerical algorithm to reconstruct a convex sound-soft scatterer from phaseless backscattering data, assuming sufficiently high frequency. Certain uniqueness and existence results for the case of circular scatterers are given as well, based on the asymptotic expansion for the normal derivative of the total field.

In this paper, we discuss the competition between the stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) instabilities under the strong damping condition. Based on a five-wave interaction model, relations of the stationary backscattering reflectivity between SRS and SBS are deduced in the case of homogeneous plasmas. Developments of the two coexistent instabilities are simulated with different parameters. The density and the temperature of plasma are found to be important in determining which instability dominates the backscattering in the regime of competition. Furthermore, the influence of inhomogeneous condition to the pattern of competition is analyzed. Numerical results consist with our theoretical results.

In the present paper, we estimated backscattering factors for the TLD and active personaldosimeters using 662 keV gamma-ray photons on a PMMA surface, which are, for the TLD,1.12; Dosicard, 1.116; DRD, 0.99; and Saphydose, 1.073, and on a water slab phantomsurface; for the TLD, 1.115; Dosicard, 1.112; DRD, 1; and Saphydose, 1.059. Thebackscattering factor contribution for the Saphydose is nearly half that of the TLD andDosicard, whereas it is zero for the DRD. The DRD underestimates Hp(10)by 10.3–11.6%, whereas for the Saphydose it is 3.4–5% compared with the TLD or Dosicard.The response of the DRD to Hp(10) is nearly independent of the phantom,whereas the TLD, Dosicard and Saphydose require phantoms for calibration for personalmonitoring. It is observed that the PMMA phantom contributes slightly higherbackscattering compared with the water slab phantom. The backscattering factor of theselected dosimeters is comparable with ICRU tissue already reported.