To guarantee good quality of butt laser welding with filler wire, a gap width detecting sensor and a wire feeding system has been designed.

本文针对高质量板材对接填丝激光焊的需要，设计了对缝间隙宽度检测的传感器与送丝控制系统。

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There are things that happened on this mission that the press really latched on to: the gap filler sticking out, the fact that we had great video of the belly of the shuttle and saw the little pieces flying off.

NPR: Former Astronaut on NASA Risk Assessment

"We had always expected a gap-filler with typically intermediate features such as a moderately elongate tail -- neither long nor short -- but the strange thing about Darwinopterus is that it has a head and neck just like that of advanced pterosaurs, while the rest of the skeleton, including a very long tail, is identical to that of primitive forms, " he said.

CNN: Pterodactyl fossil fills gaps in evolutionary tale