A numerical study is presented,using a homogenization technique to consider the plain strain problem of visco-plastic porous medium shaped by regularly distributed circular particles. Based on a rigid plastic material...A numerical study is presented,using a homogenization technique to consider the plain strain problem of visco-plastic porous medium shaped by regularly distributed circular particles. Based on a rigid plastic material,the paper derives the macroscopic constitutive laws for homogenous equivalent medium. By changing the shape parameter of circular particles,the effect of pore shape on macroscopic constitutive laws is explored. Yield surfaces with different pore shapes are obtained. About voids,a two-scale conception is introduced,which regards main void as macroscopic scale and secondary cavities as microscopic scale. The macroscopic potential involving main and secondary voids is achieved. The proposed macroscopic constitutive law taking microscopic features as influence factors is helpful for exploring the macroscopic mechanical properties of porous medium when numerical simulation is required.展开更多
In order to increase the watermarking capacity and improve the anti-counterfeiting performance of quick response （QR） two-dimensional （2D） barcode based on digital watermarking technique, this paper proposes a kin...In order to increase the watermarking capacity and improve the anti-counterfeiting performance of quick response （QR） two-dimensional （2D） barcode based on digital watermarking technique, this paper proposes a kind of graying algorithm for binary image to make transform domain watermarking methods possible. Based on the graying Mgorithm, the quantizatiombased watermarking scheme in discrete wavelet transform （DWT） domain is then designed. The experiments show that the proposed watermarking scheme for QR 2D barcode greatly improves anti-counterfeiting performance without loss of any barcode information.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.10972162)
文摘A numerical study is presented,using a homogenization technique to consider the plain strain problem of visco-plastic porous medium shaped by regularly distributed circular particles. Based on a rigid plastic material,the paper derives the macroscopic constitutive laws for homogenous equivalent medium. By changing the shape parameter of circular particles,the effect of pore shape on macroscopic constitutive laws is explored. Yield surfaces with different pore shapes are obtained. About voids,a two-scale conception is introduced,which regards main void as macroscopic scale and secondary cavities as microscopic scale. The macroscopic potential involving main and secondary voids is achieved. The proposed macroscopic constitutive law taking microscopic features as influence factors is helpful for exploring the macroscopic mechanical properties of porous medium when numerical simulation is required.
基金the National Natural Science Foundation of China(No.60903203)the Fujian Educational Bureau JK Projects(No.JK2012044)the Xiamen Municipal Science and Technology Plan Projects(No.3502Z20103036)
文摘In order to increase the watermarking capacity and improve the anti-counterfeiting performance of quick response （QR） two-dimensional （2D） barcode based on digital watermarking technique, this paper proposes a kind of graying algorithm for binary image to make transform domain watermarking methods possible. Based on the graying Mgorithm, the quantizatiombased watermarking scheme in discrete wavelet transform （DWT） domain is then designed. The experiments show that the proposed watermarking scheme for QR 2D barcode greatly improves anti-counterfeiting performance without loss of any barcode information.
