“…The excitation electrical signal for PSSAs: (a) the sawtooth waveform (Bansevicius and Blechertas, 2008; Chang and Li, 1999; Chu and Fan, 2006; Fan et al, 2019; Gao et al, 2019a, 2019b; Higuchi et al, 1990; Huang and Sun, 2019; Huang et al, 2011, 2012, 2016, 2020; Hunstig, 2017; Kurosawa and Ueha, 1991; Lee et al, 2007; Li et al, 2015a, 2017a, 2018b, 2019c, 2020c; Liu et al, 2012, 2019a; Lyding et al, 1988; Mashimo, 2014; Oubellil et al, 2019; Pan et al, 2016, 2019; Pohl, 1987a; Qin et al, 2019b; Salim et al, 2018; Shao et al, 2019a, 2019b; Smith et al, 1996; Song et al, 2018; Tang et al, 2020; Tomikawa et al, 1989; Wang and Lu, 2012; Wang et al, 2011, 2017c, 2019d, 2019e, 2019f; Wen et al, 2013; Xu et al, 2020; Yang et al, 2019, 2020b; Yu et al, 2020; Zesch et al, 1995; Zhang et al, 2019a), (b) the improvement of waveform shaping of stick phase (Hunstig et al, 2013a, 2013b; Wang and Lu, 2012; Zhang et al, 2018), (c) the improvement of waveform shaping of slip phase (Cheng et al, 2016, 2017b; Guo et al, 2019; Wang et al, 2016a), (d) the cycloid waveform (Bordoni et al, 1994; Chang and Li, 1999…”