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To study the influence of the non-uniform demagnetization of permanent magnets (PMs) on motor performance, this paper takes a two-phase four-pole Permanent Magnet Synchronous Motor (PMSM) as the research specimen. The influences of torque, phase current, back electromotive force (back-EMF), and radial magnetic density with different grades and types of demagnetization are analyzed. The simulation results show that as the degree of nonuniform demagnetization increases, the output torque and radial magnetic density gradually decrease, on the other hand, the phase current gradually increases. According to the change law of the amplitude of some harmonics of the back-EMF, it can be judged whether the motor has non-uniform demagnetization. This research conclusion can provide a theoretical basis for fault diagnosis of motor demagnetization.

In the process of predicting the remaining cutter life (RUL), the deep learning method such as convolutional neural network (CNN) does not consider the time correlation of different degradation states, which directly affects the accuracy of the remaining cutter life prediction. To extract the features with time series information to predict the RUL more effectively, this paper proposes a new deep neural network, which is named the multi-scale cyclic convolutional neural network (MSRCNN). In the MSRCNN, a cyclic convolutional layer is constructed to simulate the time correlation of different degradation states for mining the timing characteristics of the data. Multi-scale features are extracted through multi-scale convolution, and the convergence of parameters is improved by layer-by-layer training and fine-tuning. Finally, the RUL is predicted based on the features. The comparison with the published prediction methods of CNN and recurrent neural network (RNN) models proves that our proposed method (MSRCNN) is effective and superior in improving the accuracy of RUL prediction.

Significant electromagnetic pulses (EMP) can be generated by the intensive laser irradiating solid targets in inertial confinement fusion (ICF). To evaluate the EMP intensity and distribution in and outside the laser chamber, we designed and fabricated a discone antenna with ultra-wide bands of over 10 GHz. The return loss (S11 parameter) of this antenna was below −10 dB and could even achieve under −30 dB at 3.1 GHz. The EMP intensity in this study at 80 cm and 40 cm away from the target chamber center (TCC) reached 400 kV/m and 2000 kV/m. The current results are expected to offer preliminary information to study physics regarding laser plasma interactions and will also lay experimental foundation for EMI shielding design to protect various diagnostics.