Estimation of oscillation periods based on the x-t maps and the velocity components. The top row of panels displays the x-t maps for oscillation-1 and oscillation-2. In these maps, dotted circles indicate the locations of the centers of the oscillating threads, while solid red curves represent the best-fit function (B.1) to those points. The estimated periods and amplitudes are shown on the panels. The bottom row of panels presents the FFT power spectrum for each velocity component: v_x in green, v_y in red, and v_z in blue. The vertical dotted lines in these panels mark the locations of the dominant periods of v_x, while the horizontal dashed lines outline the 95% significance level.