It is presented that in gear-hobbing machine by unsnapping the change-gears and rotating the gear d,angular correction cutting will be simple and convenient and with high accuracy.

According to the analysis of the monitoring data, the abnormal tangential displacement behavior of the crest of Fengtan vierendeel gra vity-arch dam has been discovered.

The approximate formula of the changing value of wall thickness of the inner and outer side of the tube and the formula of the tangential strain are presented,which may be applied to practical production after amending.

It was found that during the no_mandrel bending forming process of minor diameter tube,the actual tangential strain along pipeline direction was approximately distributed in parabola,and the maximum strain appeared around the intermediate section of the bending angle.

Furthermore,having taken into account the effect of tangential distortion and gradient of the pixels,so this approach has a more widely application.

In the Fourier Transform Profilometry(FTP),on the base of pin-hole modle and thoroughly considering the radial distortion and the tangential distortion,the measuring system is adjusted applying the information of the image center rigeon where the ditortion can be ignored.

But only radial distortion is considered in his camera model,and when the tangential distortion is distinc tin some lenses,such as in fish eye-lenses ,the camera model will beunsui table.