"Tuning frictional behavior on the fly has been a long-standing engineering dream," said co-author Katia Bertoldi of Harvard University. "This new insight into how surface geometry governs slip pulses paves the way for tunable frictional metamaterials that can transition from low-friction to high-grip states on demand.” In addition, the dynamics revealed by these results are similar to those of tectonic faults and thus give scientists a new model for the mechanics of earthquakes, according to their new paper published in the journal Nature.
A viewing spot with the clearest view of the horizon is best, particularly to see Mercury and Venus, which will appear very low in the sky.
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这两年，这个价位段的竞争要比以前激烈了不少。看看现在的销量榜单，比亚迪早就筑起了高墙，吉利星愿和五菱宾果也各自占据了一方天地。这些车型都很成熟，续航够用、空间够用、配置够用。它们经过了市场的筛选，非常懂得如何在成本的红线内跳舞。
63-летняя Деми Мур вышла в свет с неожиданной стрижкой17:54