In an adaptive optical system,the object tracking error primally censists of the tracking error induced by the incompletely compensated atmospheric turbulence and the telescope vibration and the tilt noise error.

Depth error in depth migration profile isn't equal to velocity error, sometimes it is twice as many as velocity error.

For a long time,the analysis of the velocity error almost were rarely quantitative,and only valid to the simple geology condition.

In obserations of the Earth s atmosphere with the GPS radio occultation technique,some factors such as the position error of GPS and LEO satellite,velocity error,clock drift,and observation error of carrier wave can bring error to the retrieval atmospheric parameters.

Numerical value method is derived on the basis of structure model of NC machine tools feed system How the process error from gain,speed error,system frequency and steady position error of respond of system affect the process precision is analysed,and some principles of selecting parameters are also put forwr

The process errors caused by g ain,speed error and system frequency feature and the effect of steady sta te position error of response on the imp rovement of processing precision we re analyzed.