鹦鹉螺化石，这些螺旋状的贝壳，经常分布在二叠纪的化石群中。
Ammonoids, with their tightly coiled, spiral shells, are also widespread in the Permian fossil record.
螺旋桨采用升力面理论涡格法、吊舱采用面元法分析计算，二者的相互干扰通过叠代计算来处理。
The propeller blades are calculated by a vortex lattice method, while the pod including its strut by a boundary element method for non-lifting bodies.
以线圈耦合系数和电感分布电容模型为基础，设计优化了平面螺旋电感和叠层电感。
Based on the guidelines of the distributed capacitance mode and coupling coefficient formula, the stacked and planar inductors are designed.
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