A research model of plasma flow field and electromagnetic (EM) wave around the hypersonic vehicle for solving the blackout problem is developed in this study. Based on the computational fluid dynamics simulation, the plasma flow fields are derived and serve as the background conditions in EM wave transmission. The complicated behavior of blackout is clarified at several altitudes. Moreover, the comparations of VHF (Very-High-Frequency) blackout data between the flight tests and numerical simulations verify the validity of numerical method. In addition, the external magnetic field is applied to this model. The effects of RHCP (right hand circularly polarized), LHCP (left hand circularly polarized) waves and magnetic induction are studied, and the results show that external magnetic field can effectively reduce the transmission attenuation, and the blackout problems can be solved when the proper strength of the magnetic field is applied.
A binocular 3D sensor vision system is made on the demand of 3D measurement of teeth surface profile and the invisibility of part of the teeth profile for the result of its complexity. This system adopts line laser to illuminate perpendicularly based on laser triangulation measurement principle which is simple and precise. We use the improved threshold barycenter method to extract the light center, which removed interferences of diffuse reflection and promoted accuracy. On this basis, we use two cameras to photograph the teeth model to calibrate this system by way of polynomial fitting. After that, we use ICP algorithm to fuse 3D point clouds of the teeth model collected by two cameras, and then the 3D reconstruction of teeth model is carried out through surface interpolation. The experimental results excellently showed the teeth model surface profile.
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