For passive material such as F5, it could cause negative effect at low flow velocity when cathodic protection was applied.

对于钝化材料(如F 5)在低流速条件下施加阴极保护可能出现负效应。

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But it is a kind of soft material. Both wave velocity and wave impedance are very low. So experimental study of its dynamic mechanical behaviors is difficult.

但由于它是一种柔性材料，波速和波阻抗均极低，因此实验研究其动态力学性能具有很大困难。

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In recent tests at the company's Advanced Technology Centre in Bristol, a special liquid has been used to construct a material that is thinner than normal body armour and yet is able to stop a low-velocity bullet.

ECONOMIST: Monitor: Fluid defences | The