He was caught in a dilemma and set down a desperate elegy,in a transient lifetime,for the forerunner.

When milling and grinding a close plane contour curve on a CNC machine tool, We must select a reasonable curve for the feeding and relieving of the cutter during programming, so as to keep perfect the normal geometric shape at the feeding/relieving point on the contour curve.

Because of some factors including the error exists in the color sign printed on packaging material,the advance and retread of packaging material and other influence such as the fluctuation appears during operation,the designed sealing part may be moved in the high-speed running process,as a result,the sealing effect and production efficiency are influenced seriously.

Combined direction difference quotient method with advance and retreat method in structural optimization of discrete variables, mix arithmetic is presented in structural optimization of discrete variables, whose main body is based on direction difference quotient method.