For friction stir spot welded (FSSW) magnesium-aluminium joints, the formation of Mg-Al intermetallics in the hook region and cracking at the interface damaged seriously the strength of Mg-Al joints, resulting in lower joint load of only 0.8 ± 0.2 kN. When adding the hot-dipped Zn coating on the Al substrate surface prior to FSSW, a brazed layer, composed of Mg-Zn and Al-Zn diffusion zones at the edge of the shoulder, and a transition layer, composed of MgZn 2 , Zn-rich zone and residual Zn in the hook region, were formed in the FSSW Mg-Al joint, eliminating the cracking and Mg-Al intermetallics in the FSSW joint without the Zn coating. The load of the joint with the Zn coating increased to 3.7 ± 0.3 kN.

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Photometric observation is one of the most important means to understand the fundamental properties of asteroids. As more and more photometric data are obtained, expanding effectively the number of samples on the spin states of asteroids has become an important research topic. To obtain a preliminary solution of the spin state without statistical discrepancy by the photometric observations derived from a handful of apparitions, a moderate‐complexity shape model consisting of eight adjacent octants with different semiaxes, namely cellinoid ellipsoid, can be adopted. Using this model and employing a Markov chain Monte Carlo (MCMC) method, the spin states of four asteroids are discussed based on the existing photometric data.

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