The properties of chaotic advection arising from defect turbulence, that is, weak turbulence in the electroconvection of nematic liquid crystals, were experimentally investigated. Defect turbulence is a phenomenon in which fluctuations of convective rolls arise and are globally disturbed while maintaining convective rolls locally. The time-dependent diffusion coefficient, as measured from the motion of a tagged particle driven by the turbulence, was used to clarify the dependence of the type of diffusion on coarse-graining time. The results showed that, as coarse-graining time increases, the type of diffusion changes from superdiffusion → subdiffusion → normal diffusion. The change in diffusive properties over the observed timescale reflects the coexistence of local order and global disorder in the defect turbulence.

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In this study, a small-scale wind turbine for the mountainous area is developed. The technical features of this wind turbine are the high performance rotor with a blade tip-mounted Mie vane, the passive power control by a pitch-flap mechanism and a variable speed induction generator with inverter system. The test wind turbine is tested in Mie University wind turbine test field in a mountainous area. The output power performance, the passive power control in high wind speed, the performance improvement by the variable speed operation and the quality of power are discussed. As the results, it is demonstrated the power control by a passive pitch-flap mechanism, the suppressing effects for the fluctuating moments on the blade root and the characteristics of the variable speed generating system. Some flow patterns on the blade are shown.

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