A novel approach of printed circuit board(PCB)image locating is presented Based on the rectangle mark image edge of PCB,the featur es is used to describe the image edge and the fractal properby of image edge is anal...A novel approach of printed circuit board(PCB)image locating is presented Based on the rectangle mark image edge of PCB,the featur es is used to describe the image edge and the fractal properby of image edge is analyzed It is proved that the rectangle mark image edge of PCB has some fractal features A method of deleting unordinary curve noise and compensating the length of the fractal curve is put forward,which can get the fractal dimension value from one complex edge fractal property curve The relation between the dim ension of the fractal curve and the turning angle of image can be acquired from an equation,as a result,the angle value of the PCB image is got exactly A real image edge analysis result confirms that the method based on the fractal theory is a new powerful tool for angle locating on PCB and related image area.展开更多
In the casting process,in order to compensate for the solidification shrinkage to obtain higher dimensional accuracy of the casting,it is often necessary to modify the original design of castings,and a suitable compen...In the casting process,in order to compensate for the solidification shrinkage to obtain higher dimensional accuracy of the casting,it is often necessary to modify the original design of castings,and a suitable compensation method has a decisive impact on the dimensional accuracy of the actual casting.In this study,based on solidification simulation,a design method of reverse deformation is proposed,and two compensation methods,empirical compensation and direct reverse deformation,are implemented.The simulation results show that the empirical compensation method has problems such as difficulty in determining the parameters and satisfaction of both the overall and local accuracy at the same time;while based on the simulation results for each node of the casting,the direct reverse deformation design achieves the design with shape.In addition,the casting model can be optimized through iterative revisions,so that higher dimensional accuracy can be continuously obtained in the subsequent design process.Therefore,the direct reverse deformation design is more accurate and reasonable compared to empirical compensation method.展开更多
文摘A novel approach of printed circuit board(PCB)image locating is presented Based on the rectangle mark image edge of PCB,the featur es is used to describe the image edge and the fractal properby of image edge is analyzed It is proved that the rectangle mark image edge of PCB has some fractal features A method of deleting unordinary curve noise and compensating the length of the fractal curve is put forward,which can get the fractal dimension value from one complex edge fractal property curve The relation between the dim ension of the fractal curve and the turning angle of image can be acquired from an equation,as a result,the angle value of the PCB image is got exactly A real image edge analysis result confirms that the method based on the fractal theory is a new powerful tool for angle locating on PCB and related image area.
基金This study was financially supported by the National Key Research and Development Program of China(No.2020YFB2008302).
文摘In the casting process,in order to compensate for the solidification shrinkage to obtain higher dimensional accuracy of the casting,it is often necessary to modify the original design of castings,and a suitable compensation method has a decisive impact on the dimensional accuracy of the actual casting.In this study,based on solidification simulation,a design method of reverse deformation is proposed,and two compensation methods,empirical compensation and direct reverse deformation,are implemented.The simulation results show that the empirical compensation method has problems such as difficulty in determining the parameters and satisfaction of both the overall and local accuracy at the same time;while based on the simulation results for each node of the casting,the direct reverse deformation design achieves the design with shape.In addition,the casting model can be optimized through iterative revisions,so that higher dimensional accuracy can be continuously obtained in the subsequent design process.Therefore,the direct reverse deformation design is more accurate and reasonable compared to empirical compensation method.
