Synergy of melting wave and electromagnetic force on the transition mechanism is studied in this paper. The 3-D electromagnetic field, temperature field, and structure field coupling model are established to simulate the velocity skin effect and melting wave phenomenon. It is found that the melting wave and electromagnetic force together lead to the occurrence of transition. And the two are inextricably linked. The melting wave will enlarge the separating electromagnetic force on the armature trailing arm. The separating electromagnetic force may result in the reduction of contact area, which would accelerate the melting wave. It is getting worse and worse, eventually lead to the transition. And the analytical results are consistent with the experimental phenomena. The transition prediction method will be more accurate when combining the melt-wave and the electromagnetic force.

In this paper, a research on the damages of material caused by thermal stress in electromagnetic launch is presented. 3-D finite-element program is established to calculate the transient electromagnetic fields and temperature fields including a moving armature. The focus is mainly on the high temperature and large thermal stress damages to the rail. Thermal stress is produced by the current density concentration and defined as the skin effect. There are two main reasons for the current skin effect. One is due to the rapid changes of the current wave. The other is due to the moving conductors known as the velocity skin effect. The simulation results illustrate that with the influence of the current skin effect, the thermal stress will concentrate at a small area. This area may cause the grooving damage at startup, besides, the gouging damage at high velocity. Finally, the results are in agreement with the experiments.

With numerous applications in the field of intelligent unmanned systems for flight patrol, airborne cameras have become crucial tools for measuring and tracking targets. However, the video captured by these cameras is susceptible to external disturbances and jitter, and traditional stabilizers often fail to accurately extract image feature points. Although deep learning approaches can stabilize videos, they are constrained by limited datasets and weak model controllability, making it challenging to achieve real-time performance. We introduce a SuperPoint stabilization framework based on deep learning feature point detection. By combining traditional and deep learning methods, our approach aims to construct a controllable and real-time video stabilizer. First, we extract image feature points using SuperPoint neural network, which is better than traditional manual feature point detector. Second, the extracted image feature points are homogenized. Third, we adopt the pyramid Lucas–Kanade (LK) to improve feature points matching speed and the accuracy for motion estimation. Finally, we define the moving average filter and the Kalman filter, respectively, and combine them to smooth unstable camera trajectories and then output stable video sequences after motion compensation. Experimental results show that our proposed method produces competitive results with current representative methods, and more importantly, it only takes an average of 32 ms to stabilize a frame, which is faster than others.

For the stability of the spinning projectile launched by a railgun, calculation is carried out to analyze the influence of the arm edge effect (AEE). The AEE refers to that when the edge of an arm is in contact with the edge of a rail, it may produce an asymmetric electromagnetic to create an extra rotation torque. Since the current skin effect may change the magnetic field distribution when some current flow through the arm’s edge. A finite element model is established to simulate the AEE. Results show that for the projectile with separated arms, the AEE may cause the rotation torque to reverse, and the rotation torque may vary alternately between positive and negative value. When increasing the number of arms, the variation amplitude of torque is decreasing and closer to the average value. However, increasing the number of arms will also weaken its strength, so this is not a good method. Therefore, this article proposes an improved projectile, which is connecting the rear arms by a ring. This allows the current to enter the ring first and then into the arms, what may keep the rotation torque constant, and increase the strength. This article may have important guiding significance for the research of launching spinning projectile by a railgun.