无环的

This paper proposes an self-adaptive speed-accommodating control circuit,which can get the speed-error,and can test the change of frequency of feedback signals of the single phase ac tacho generator through self comparing and automatically corrects the speed.

文章介绍了通过自比较来检测录音机主导轴单相永磁交流测速发电机反馈信号的频率变化，从而获得速度误差，并自动校正转速的一种自适应速度调节控制电路。

A mesoscale convergence line, which is formed by downslope wind from the Taihang Mts. Converging with southwest warm humid wind in front of a surface trough, induces the release of the CAPE and initiates convection and organizes the convective cells into a squall line.

由于太行山地形影响而产生的下坡风与地面低压槽前的西南暖湿气流相汇合，形成中尺度辐合线，触发了不稳定能量的释放，产生对流并由中尺度辐合线组成飑线。