Abstract: The present invention relates to a groundwater circulation well system with pressure-adjustable hydrodynamic cavitation, including a circulation well body, a sucked and injected water circulation assembly and a hydrodynamic cavitator. The sucked and injected water circulation assembly is based on a water suction and injection pump. The hydrodynamic cavitator is provided, inside a vortex chamber, with a vortex water inlet column capable of changing a water passing aperture. The hydrodynamic cavitator is capable of changing a bubbling pressure and a breaking pressure of hydrodynamic cavitation bubbles in the vortex water inlet column. The hydrodynamic cavitator generates vortices in the circulation well body to accelerate uniform mixing of a remediation agent and the groundwater. Energy from collapsing and bursting of the hydrodynamic cavitation bubbles activates the remediation agent such that contaminants in the groundwater are efficiently degraded.

Abstract: A frequency detection method based on synchronous oscillation of resonators, and a tilt sensor using the frequency detection method are disclosed. The sensor includes a detecting unit and a synchronization unit which are respectively disposed in a first oscillating circuit and a second oscillating circuit for forming two self-excited oscillators. The detecting unit and the synchronization unit are electrostatically coupled through a plate capacitor to allow a weak synchronous current to pass through, which affects and reduces phase noise of the self-excited oscillator formed by the detecting unit, thereby greatly improving the frequency stability thereof and simultaneously reading out a natural frequency thereof through a frequency counter. Three detecting units are respectively evenly distributed at a periphery of a hexagonal mass block through magnifying beams. The mass block is configured to sense a gravitational acceleration.