S U M M A R Y The differential attenuation for upper-mantle paths beneath northern Australia has been estimated using spectral ratio methods, both in a narrow frequency band near 0.6 Hz to obtain stable estimates for subsequent inversion and also over a broad frequency band up to 3–6 Hz to look at the frequency dependence of attenuation. The frequency dependence of the differential attenuation ...

Sea ice attenuates waves propagating from the open ocean. Here, we model evolution of energetic unidirectional random in marginal zone with a nonlinear Schrödinger equation, frequency dependent dissipative term consistent current paradigms and recent field observations. The preferential dissipation high components results concurrent downshift spectral peak that leads to less than exponential en...

Industrial inspection protocols are qualified using mock-ups manufactured according to the same procedure as plant part. For coarse-grained castings, known for their low inspectability, relying on becomes particularly challenging owing variability of grain properties among components. Consequently, there is a keen interest in capability verify whether size component under test matches qualifica...

Experience with diffusion-weighted imaging (DWI) shows that signal attenuation is consistent with a multicompartmental theory of water diffusion in the brain. The source of this so-called nonexponential behavior is a topic of debate, because the cerebral cortex contains considerable microscopic heterogeneity and is therefore difficult to model. To account for this heterogeneity and understand i...

I For the design of existing low rate powerline communication systems it was sufficient to model the channel with parameters such as attenuation, impedance and noise. For high speed power line communication, however, it is important not to model the attenuation only but the complete linear channel distortion. In this paper we present a novel method of measuring the impulse response of the power...

Previous reports have shown that the variance in ultrasound attenuation measurements is reduced when spatial and frequency compounding were applied in data acquisition and analysis. This paper investigates factors affecting the efficiency of compound attenuation imaging methods. A theoretical expression is derived that predicts the correlation between attenuation versus frequency slope (beta) e...

Synthetic seismograms produced by the finite difference method are used to study the scattering of elastic and acoustic waves in two-dimensional media with random spatial variations in seismic velocity. The results of this study provide important insights about the propagation of short-period (< 1 s) seismic waves in the earth's crust and place significant constraints on the fluctuation spectru...

introduction:  the use of radioactive iodine (131i) has become an important adjunct to the treatment of thyroid cancer and hyperthyroidism. salivary gland has the ability to concentrate radioactive iodine under normal circumstances. salivary gland dysfunction and dry mouth are the common side effectsof high-dose radioiodine therapy. the purposeof this study was to determine the absorbed dose of...

the matrix functions appear in several applications in engineering and sciences. the computation of these functions almost involved complicated theory. thus, improving the concept theoretically seems unavoidable to obtain some new relations and algorithms for evaluating these functions. the aim of this paper is proposing some new reciprocal for the function of block anti diagonal matrices. more...