Tomas Gomez Alvarez-Arenas

TL;DR: In this paper, the authors investigate material requirements to produce impedance matching layers for air-coupled piezoelectric transducers, identify materials that meet these requirements, and propose the best solution to produce air coupled PPI transducers for the low megahertz frequency range.

TL;DR: In this article, the directional freezing of microfiber suspensions is used to assemble highly porous (porosities ranging between 92% and 98%) SiC networks, which exhibit a unique hierarchical architecture in which thin layers with honeycomb-like structure and internal strut length in the order of 1-10 μm in size are aligned with an interlayer spacing ranging between 15 and 50 μm.

TL;DR: Soft and open-porous product structures exhibited a better transmission of acoustic energy and were more prone to the mechanical effects of ultrasound, while materials with a hard and closed-compact structure were less affected by acoustic energy due to the fact that the significant impedance differences between the product and the air cause high energy losses on the interface.

TL;DR: The design, construction and characterization of air-coupled piezoelectric transducers using 1–3 connectivity piezocomposite disks with a stack of matching layers with an active quarter wavelength layer made of polypropylene foam ferroelectret film are presented.

TL;DR: Study of structural changes experienced by Quercus muehlenbergii leaves during dehydration in terms of ultrasounds measurements, cell wall elasticity, leaf thickness, leaf density, and leaf structure suggests that the decrease found in f/f(o) before the turgor loss point can be attributed to the occurrence of changes in the estimation of the macroscopic effective elastic constant of the leaf.