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This paper studies the detection of weak signal detection using a Duffing Oscillator, which is sensitive to periodic signals but insensitive to noises. The system transits from chaotic to great periodic motion when coupled to the weak periodic signal to be detected. To efficiently determine the phase transition, a novel numerical criterion is proposed based on the sharp increase of variance when phase change happens. Simulation results verified the effectiveness of this method.

In order to develop actuation circuit for high pressure common rail injector solenoid valve, the high and low voltage time-sharing actuation control method based on current feedback was researched. A finite state machine tool called stateflow was used to establish the actuation model of solenoid, and the intelligent actuation control circuit was developed according to the model and MCU. The driving current can be adjusted automatically according to “Peak-High-Low” three-stage current, and the circuit can troubleshoot the state of solenoid. Driving Experiments on solenoid and injector were carried out and the results show the good performance of the intelligent actuation control circuit.