给定一个单向链表，如何判断它里面是否有环存在。
配注器装有孔口阀和单向阀系统，使泵入的流体沿环空向下或沿注入管线向下进入生产导管。
The injection mandrel is equipped with a port - and check-valve system to direct fluid pumped down the annulus or injection line into the production conduit.
与传统方案相比，IBAS（综合宽带接入系统）所采用的两纤单向通道倒换环具有更好的优越性。
To compare with the traditional scheme, the two-fiber single direction channel rotating ring used in IBAS shows more superior.
在两个单环并、交、差图形运算的基础上，提出通过搭接单向桥边的方法，将单环算法直接向多外环、多内环拓展。
The algorithm of two loops (single loop) Boolean operation and the algorithm of the one-way bridge edge are presented.
通过气缸带动一个活塞抽取和打出物料，并由单向阀控制物料流向，由磁环开关控制气缸行程，即调节灌装量。
The cylinder drives a piston extraction and play materials, and by the one-way valve to control the flow of materials, the magnetic switch control cylinder stroke, which adjust the filling volume.
它主要由内筒、外筒、带有单向阀的活塞、溢流件、调节环，密封圈等组成。
The leakproof hydraulic damper is mainly composed of an inner cylinder, an outer cylinder, a piston which is provided with one-way valves, overflow members, adjustment rings, seal rings, etc.
它主要由内筒、外筒、带有单向阀的活塞、溢流件、调节环，密封圈等组成。
The leakproof hydraulic damper is mainly composed of an inner cylinder, an outer cylinder, a piston which is provided with one-way valves, overflow members, adjustment rings, seal rings, etc.
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