###### Abstract
[9] employ wavenumber filtering to remove Lamb modes other than the A0 mode to detect flat bottom holes in a plate. [PERSON] et al. [10] propose a methodology for nondestructive inspection of cylindrical storage tanks' base plates whereby a transducer is scanned around the perimeter of the base plate. The generated fundamental SH waves propagate in the radial direction of the base plate. Defects scatter the waves, and reflections are received by the transducer. A synthetic aperture focusing technique based on the so-called exploding reflector model is applied to image the tank bottom. [PERSON] et al. [11] then demonstrate a 12 dB improvement in the amplitude of SH waves generated by a magnetostrictive transducer when a soft magnetic patch is applied, which reduces the resistance of the magnetic circuit. This optimization of the magnetic circuit is also applicable to transducers that send and receive torsional waves in pipes. [PERSON] et al. [12] propose an experimental method to construct the Lamb wave and SH wave dispersion curves for a plate using a transmitter and two receivers, which requires no knowledge of the material properties. The paper by [PERSON] et al. [13] completes the applications to plates by investigating the integrity of the adhesive in single-lap joints between aluminum plates by images processed from the wavefield acquired by scanning laser Doppler vibrometer and the weighted root mean square. Axial transmission of ultrasound in human cortical bone is under development as a biomarker for early detection of osteoporosis and fracture risk. While the geometry of human bones, such as the tibia, is far from the geometry of plates, it is common to use Lamb waves as surrogates for waves in cortical bones. [PERSON] et al. [14] developed a rapid high-resolution technique to determine the wavenumbers of propagating waves in surrogates for human bone. One manuscript addresses Rayleigh waves propagating along the surface of a half-space. [PERSON] et al. [15] provide forward and inverse analyses of Rayleigh wave scattering from surface breaking defects based on reflection coefficients in order to predict the shape of realistic surface-breaking flaws. The final four manuscripts investigate defect localization for long-range inspection of different types of one-dimensional waveguides. [PERSON] et al. [16] considered long-range ultrasonic guided waves in a steel square bar and analyzed the non-detection zone for flaws located near the back wall. [PERSON] et al. [17] propose a single mode extraction algorithm to precisely localize defects in rail. [PERSON] et al. [18] analyze guided waves, including second harmonic generation associated with the contact acoustic nonlinearity, in multi-strand cable where transducers are coupled to only two strands in the cable. Finally, [PERSON] and [PERSON] [19] investigate accurate group velocity of electromagnetic waves in dispersive waveguides, such as insulated cables, in which defect localization is performed using reflectometry. This research received no external funding. I would like to thank all of the authors who submitted manuscripts to this special issue, as well as the reviewers, who helped to improve the quality of the manuscripts. The author declares no conflicts of interest.