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The α - F composite fading distribution with pointing errors is investigated in this paper. New expressions for the probability density function and cumulative distribution function of the envelope/instantaneous signal-to-noise ratio (SNR), higher-order moments, and moment generating function of the instantaneous SNR are derived. Based on the aforementioned statistics, expressions for the outage probability, symbol error probability, and ergodic channel capacity are obtained. An asymptotic analysis is also provided. Furthermore, an application of the α - F model with pointing errors in a wireless emerging system, namely reconfigurable intelligent surfaces (RIS), is shown. Several curves, corroborated by Monte–Carlo simulations, are presented for different values that characterize the channel and pointing error parameters. [ABSTRACT FROM AUTHOR]

Abstract We experimentally and numerically investigated the shear response of a three-dimensional (3D) non-woven carbon fibre reinforced epoxy composite with three sets of orthogonal tows and approximately equal fibre volume fractions in the orthogonal directions. Shear tests on two orientations of dogbone specimens showed significant strain hardening and an increasing unloading stiffnesses with increasing applied strain. Unloading was also accompanied by considerable strain recovery, with X-ray tomographic scans revealing minimal damage accumulation in specimens until near final failure at shear strains in excess of 50%. To understand the origins of this unusual mechanical response of the 3D carbon fibre composites, we developed a micro-mechanical model wherein all tows and matrix pockets in the composite are explicitly considered. The tows were modelled using a pressure-dependent crystal plasticity approach to capture texture evolution under large deformations and the model replicated many of the experimental observations with a high degree of fidelity. Importantly, the model illustrated the role of the 3D architecture in not only suppressing delamination but also enhancing the strain hardening response due to a 3D confinement effect of the tow architecture. On the other hand, a model wherein the tows were modelled using an anisotropic Hill plasticity framework (absent plastic spin) failed to replicate the observed strain hardening response or capture the associated strain recovery upon unloading. This highlights the importance of accounting for the evolution of the material substructure within the tows of these high ductility 3D composites. The results of this work illustrate the unique mechanical behaviour of 3D non-woven fibre composites and provide insight into how 3D fibre architecture can be used to enhance the mechanical performance of fibre composites. [ABSTRACT FROM AUTHOR]

The article presents the poem "Let's Go!" by R. Desha Lucas. First Line: About a fiddlefoot, I'd say; Last Line: And when at home, awaysick.