To predict helicopter vortex ring state boundary is necessary for flight safety.

直升机涡环状态边界的确定对直升机飞行安全具有重要意义。

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An experimental study of inlaid circular ring under impact force on interior boundary is also conducted. The result shows that the stress is distributed within a limited scope.

对内边界受冲击力作用的镶嵌圆环也进行了实验研究，结果表明，应力分布局限在有限范围内。

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This paper gives a solution of the characteristic equations of the boundary conditions of the dielectric ring loaded horn.

本文对介质环加载边界条件特征方程进行了求解。

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He noted that, this was only possible due to the earlier approval of planning regulations for the area within boundary of the Boulevard ring.

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