Journal: Scientific Reports

Article Title: Manipulating conductivity and noise for transitioning between stochastic and inverse stochastic resonances in liquid–crystal electroconvection

doi: 10.1038/s41598-024-71897-z

Figure Lengend Snippet: AC-driven electroconvection (EC) with superposed external colored noise. ( a ) Schematic of EC driven by Coulomb forces on electric charges (+ ,−) in a nematic liquid crystal (NLC). The rods in the EC vortices indicate the director n ( n x , 0, n z ) of the NLC modulated from the initial director n 0 = (1, 0, 0) (at V = 0). Above a threshold voltage V c , EC is optically observed as a periodic roll pattern (i.e., the so-called Williams domains) in the xy plane by the lens effect of the periodic director angle φ ( x ). ( b ) Power spectra P ( f ) of colored noise characterized by the cutoff frequency f c of the pass band and the width W of the attenuation band. ( c ) Schematic of Gaussian amplitude noise (top) and phase noise (bottom) superposed on a sinusoidal AC signal. ( d ) Typical P ( f ) of noise in this study, characterized by the steepness s corresponding to W at a fixed f c ; note that s = 1 indicates W = 0 for ideal noise filters. Each P ( f ) was obtained from the noises generated by a frequency filtering program integrated into the general-purpose software (MATLAB). Compare these P ( f ) from the filtering program with that ( s = 0.80) obtained experimentally from a wave generator (HIOKI, 7075).

Article Snippet: The discrete fourth-order Runge–Kutta method within the general-purpose software MATLAB R2023b was employed to determine the threshold voltage V c of EC based on the governing Eqs. ( ) and ( ) for the Carr–Helfrich mechanism , , .

Techniques: Generated, Software