2l	Length of piezoelectric ceramics
w	Width of piezoelectric ceramics
h	Thickness of piezoelectric ceramics
$E_3$	Electric field in thickness direction
$s_{11}$	Compliance coefficient of piezoelectric ceramics
$u_1$	Displacement in longitudinal direction
$T_1$	Stress in longitudinal direction
$\rho$	Density of piezoelectric ceramics
$\kappa$	Wave number
$\omega$	Angular frequency
$S_1$	Strain in longitudinal direction
$D_3$	Electric displacement
$d_{31}$	Piezoelectric strain constant
${\epsilon }_{33}^T$	Dielectric constant of piezoelectric ceramics
$\eta$	Mechanical loss factor of piezoelectric ceramics
$\delta$	Dielectric loss factor of piezoelectric ceramics
Y	Admittance of piezoelectric ceramics
Z	Impedance of piezoelectric ceramics