正文
that does not accidentally come loose. At least in part, this is because no one has truly understood why shoelaces come undone in the first place. But that crucial gap in human knowledge has just been plugged. As they report in the Proceedings of the Royal Society, Christopher Daily-Diamond, Christine Gregg and Oliver O’Reilly, a group of engineers at the University of California, Berkeley, have now worked out the mechanics of shoelace-
bow
disintegration.
从飞机到自行车，从桥梁到电脑芯片，工程设计研究为人类带来了极大的便利。尽管如此，想要发明一种不会轻易松开的鞋带仍然存在困难。至少在某种程度上来说，这是因为没有人真正清楚为什么系紧的鞋带会自己松开。但如今，人类知识体系中的这一重大缺失已经补全。加州大学伯克利分校的三名工程师Christopher Daily-Diamond、Christine Gregg和Oliver O’Reilly在英国《皇家学会学报》上刊文称，他们已经弄清了鞋带蝴蝶结自然松脱的原理机制。
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Shoelace：n. 鞋带
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Bow：n. 弓；鞠躬；船首；蝴蝶结
A shoelace bow is a type of
slip knot
that has, at its core, a
reef knot
. Like conventional reef knots, bows can be mistied as “
granny” knots
, which come undone more easily than a true reef does. But even a shoelace bow with a true reef at its core will fail eventually, and have to be retied.
鞋带蝴蝶结是一种活结，其本质属于平结。与传统的平结类似，蝴蝶结很容易被误系成顺结，而顺结比真正的平结更容易松开。但是，就算使用真正的平结来系鞋带，最终的结果也会是鞋带松开，不得不重新系扎。
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Slip knot：活结；滑结
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Reef knot：平结；缩帆结
-
Granny knot：顺结；十字结
Walking involves two mechanical processes, both of which might be expected to
exert
forces on a shoelace bow. One is the forward and back movement of the leg. The other is the impact of the shoe itself hitting the ground.
Preliminary
experiments carried out by Mr Daily-Diamond, Ms Gregg and Dr O’Reilly showed that neither of these alone is enough to persuade a bow to unravel. Both are needed. So they had to
devise
experiments which could measure and record what was going on while someone was actually walking.
人类的行走动作包含两个机械过程，而这二者都会对鞋带结造成影响。一个过程是腿部的前后运动，另一个是鞋子接触地面产生的冲击。Daily-Diamond先生、Gregg女士和O’Reilly博士开展的初步实验显示，这两个机械过程中的任何一个都不足以使鞋带结松脱，只有在二者同时作用下，鞋带结才会松开。所以，三名工程师设计了各种实验，对步行者的实际行走过程进行测量记录。
The “someone” in question was Ms Gregg, who endured numerous sessions on a
treadmill
