It is widely accepted that, on ensemble average, the transmission T of guided modes decays exponentially with the waveguide length L due to small imperfections, leading to the important figure of merit defined as the attenuation−rate coefficient α = −/L. In this letter, we evidence that the exponential−damping law is not valid in general for periodic monomode waveguides, especially as th...

Linear and mass attenuation of 0.511 MeV gamma radiations from alcohol ethanol by dilute solution of Phenol (C6H6O) studied for different concentrations. Mixture rule for theoretical calculation of attenuation coefficient is developed for the solution; our study explores the validity of the expected exponential absorption law for γ-rays radiations in solution and also provides an alternative me...

The point spread function (PSF) is an important property for predicting beam propagation and imaging system performance. Measurements of the PSF in three different locations (Pacific Ocean, Tongue of the Ocean, and Sargasso Sea) are presented. These measurements are used to validate extensive laboratory measurements [S. Q. Duntley, "Underwater Lighting by Submerged Lasers and Incandescent Sourc...

Using three-dimensional Monte Carlo radiative transfer simulations, we examine the effect of beam transmissometer geometry on the relative error in the measurement of the beam-attenuation coefficient in an aquatic environment characterized by intense light scattering, especially within submerged bubble clouds entrained by surface-wave breaking. We discuss the forward-scattering error associated...

A method is evaluated for estimating the absorption coefficient a and the backscattering coefficient b(b) from measurements of the upward and downward irradiances E(u)(z) and E(d)(z). With this method, the reflectance ratio R(z) and the downward diffuse attenuation coefficient K(d)(z) obtained from E(u)(z) and E(d)(z) are used to estimate the inherent optical properties R(infinity) and K(infini...

Natural cork enclosures, due to their cell structure, composition, and low moisture are fairly transparent to terahertz (THz) and millimeter waves enabling nondestructive evaluation of the cork's surface and interior. It is shown that the attenuation coefficient of the defect-free cork can be modeled with a Mie scattering model in the weakly scattering limit. Contrast in the THz images is a res...

Estimating total ultrasound attenuation from backscatter data is essential in the field of quantitative ultrasound (QUS) because of the need to compensate for attenuation when estimating the backscatter coefficient and QUS parameters. This work uses a reference phantom method of attenuation estimation to create a spatial map of attenuation slope (AS) from backscatter radio-frequency (RF) data o...

In this paper the propagation of harmonic plane waves in a homogeneous anisotropic magneto-piezothermoelastic diffusive body with fractional order derivative is studied. The governing equations for a homogeneous transversely isotropic body in the context of the theory of thermoelasticity with diffusion given by Sherief et al. [1] are considered as a special case. It is found that three types of...

Introduction: MR-guided focused ultrasound surgery (MRgFUS) is a non-invasive means of causing selective tissue necrosis using high-power ultrasound and MR temperature imaging (MRTI). Predicting the power deposition pattern in the inhomogeneous tissue requires a beam propagation technique that has the ability to handle inhomogeneous acoustic properties. Beyond the innate inhomogeneities of tiss...

Snow is a scattering-dominated medium whose scattering is independent of wavelength at 350-600 nm. The attenuation of solar radiation in snow can be used to infer the spectral absorption coefficient of pure ice, by reference to a known value at 600 nm. The method is applied to clean Antarctic snow; the absorption minimum is at 390 nm, and the inferred absorption coefficient is lower than even t...