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A transient multi-physics model incorporated with an electromagneto-thermomechanical coupling is developed to capture the multi-field behavior of a single-pancake (SP) insert no-insulation (NI) coil in a hybrid magnet during the charging and discharging processes. The coupled problem is resolved by means of the finite element method (FEM) for the magneto-thermo-elastic behaviors and the Runge-Kutta method for the transient responses of the electrical circuits of the hybrid superconducting magnet system. The results reveal that the transient multi-physics responses of the insert NI coil primarily depend on the charging/discharging procedure of the hybrid magnet. Moreover, a reverse azimuthal current and a compressive hoop stress are induced in the insert NI coil during the charging process, while a forward azimuthal current and a tensile hoop stress are observed during the discharging process. The induced voltages in the insert NI coil can drive the currents flowing across the radial turns where the contact resistance exists. Therefore, it brings forth significant Joule heat, causing a temperature rise and a uniform distribution of this heat in the coil turns. Accordingly, a thermally/mechanically unstable or quenching event may be encountered when a high operating current is flowing in the insert NI coil. It is numerically predicted that a quick charging will induce a compressive hoop stress which may bring a risk of buckling instability in the coil, while a discharging will not. The simulations provide an insight of hybrid superconducting magnets under transient start-up or shutdown phases which are inevitably encountered in practical applications. [ABSTRACT FROM AUTHOR]

Servo circuit of quartz flexible accelerometer is an important signal processing unit in inertial measurement system. This paper introduced the working principle of the quartz flexible accelerometer and the composition of the servo circuit. Taking the output saturation of a quartz flexible accelerometer during the test process of inertial measurement unit as an example, according to the failure analysis process of hybrid integrated accelerometer servo circuit and the fault tree analysis based on accelerometer servo circuit fault diagnosis expert system, the fault location and failure analysis of the failed circuit are carried out, and the failure mechanism and causes are studied and analyzed. The analysis results show that the failure circuit is caused by electrical damage to the differential capacitance detector in the differential capacitance–voltage converter. In view of this problem, the prevention and improvement measures are put forward to reduce the frequency of the failure mode. Above analysis and research are of guiding significance to improve the fault analysis technology and the use reliability of servo circuit of hybrid integrated quartz flexible accelerometer. [ABSTRACT FROM AUTHOR]