Search Results (2)

This study investigates pre-seismic ionospheric anomalies preceding the 2023 Jishishan Ms6.2 earthquake using total electron content (TEC) data derived from BDS geostationary orbit (GEO) satellites. Multi-scale analysis integrating Butterworth filtering and wavelet transforms resolved TEC disturbances into three distinct frequency regimes: (1) high-frequency perturbations (0.56–3.33 mHz) showed localized disturbances (amplitude ≤ 4 TECU, range < 300 km), potentially associated with near-field acoustic waves from crustal stress adjustments; (2) mid-frequency signals (0.28–0.56 mHz) exhibited anisotropic propagation (>1200 km) with azimuth-dependent N-shaped waveforms, consistent with the characteristics of acoustic–gravity waves (AGWs); and (3) low-frequency components (0.18–0.28 mHz) demonstrated phase reversal and power-law amplitude attenuation, suggesting possible lithosphere–atmosphere–ionosphere (LAI) coupling oscillations. The stark contrast between near-field residuals and far-field weak fluctuations highlighted the dominance of large-scale atmospheric gravity waves over localized acoustic disturbances. Geometry-based velocity inversion revealed incoherent high-frequency dynamics (5–30 min) versus anisotropic mid/low-frequency traveling ionospheric disturbance (TID) propagation (30–90 min) at 175–270 m/s, aligning with theoretical AGW behavior. During concurrent G1-class geomagnetic storm activity, spatial attenuation gradients and velocity anisotropy appear primarily consistent with seismogenic sources, providing insights for precursor discrimination and contributing to understanding multi-scale coupling in seismo-ionospheric systems. Full article

This paper proposes a 1000 W high-frequency three-phase power inversion underwater capacitive wireless power transfer (UCWPT) system for power delivery to autonomous underwater vehicles (AUVs). The multi-phase coupling structure is designed as a columnar configuration that conforms to the shape of AUVs. This paper innovatively presents a curved coupling coupler composed of six metal plates. This design significantly enhances the mutual capacitance of the coupling structure and the power transfer capacity of the UCWPT system. Utilizing the columnar structure, the receiver of the capacitive wireless power transfer system can be easily integrated into AUVs, reducing the installation space. Furthermore, the cylindrical dock-transmitter terminal structure of the system greatly improves the anti-misalignment capability. This addresses issues such as charging voltage and current fluctuations caused by vehicle rolling in dynamic ocean environments. Additionally, the wireless power transfer capacity is notably enhanced. An experimental platform was constructed, and tests were conducted in both air and water media. A 1000 W experimental setup was developed to validate the theoretical analysis and simulations. The experimental results align closely with the theoretical predictions. At a fixed distance of 3 cm between transmitter and receiver, peak power transfer efficiencies of 80% in air and 74% in water were achieved with stable operational performance. The cylindrical structure demonstrates robust anti-misalignment properties. Full article