Rate-distortion optimization greatly improves the performance of compression coding system so that it pervades all of the source coding from an information-theoretic standpoint and for the design of practical coding s...Rate-distortion optimization greatly improves the performance of compression coding system so that it pervades all of the source coding from an information-theoretic standpoint and for the design of practical coding systems. For the case of rate-distortion optimization,Lagrange multiplier method provides the efficient and nearly optimal solution. In this paper,a fast and efficient algorithm is proposed to solve the optimal slope λ of the rate-distortion curve at the given bit budget. Based on Lagrange multiplier method,the presented algorithm find λ using the golden-ratio search. Compared with the Bisection method that only adapts to the system with the dense operational points on the rate-distortion curve,the proposed algorithm can be adapted to the system whether the operational points are populated densely or not. Thus it can be applied to both the wavelet coding system and the video coding standards such as H.264,where Bisection method can not work well. In particular,the algorithm has been verified on the platform of the quadtree classified and trellis coded quantized (QTCQ) wavelet image compression system and the newest video coding standard H.264. The experimental results are provided to demonstrate the efficiency of the proposed algorithm. The proposed algorithm can improve the coding performance. A gain about 0.6-0.7dB can be achieved with the same rate in H.264. In addition,it converges as fast as Bisection method,with almost the same complexity.展开更多
The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with t...The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter(d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth(h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.展开更多
基金Special Foundation of Outstanding Young Teacher of ShanghaiShanghai Educational Development Foundation,China (No.2007CG66)+1 种基金Shanghai Key Research Project,China ( No.071605125,No.08160510600)Innovation Program of Shanghai Municipal Education Commission,China(No.09ZZ185,No.09YZ337)
文摘Rate-distortion optimization greatly improves the performance of compression coding system so that it pervades all of the source coding from an information-theoretic standpoint and for the design of practical coding systems. For the case of rate-distortion optimization,Lagrange multiplier method provides the efficient and nearly optimal solution. In this paper,a fast and efficient algorithm is proposed to solve the optimal slope λ of the rate-distortion curve at the given bit budget. Based on Lagrange multiplier method,the presented algorithm find λ using the golden-ratio search. Compared with the Bisection method that only adapts to the system with the dense operational points on the rate-distortion curve,the proposed algorithm can be adapted to the system whether the operational points are populated densely or not. Thus it can be applied to both the wavelet coding system and the video coding standards such as H.264,where Bisection method can not work well. In particular,the algorithm has been verified on the platform of the quadtree classified and trellis coded quantized (QTCQ) wavelet image compression system and the newest video coding standard H.264. The experimental results are provided to demonstrate the efficiency of the proposed algorithm. The proposed algorithm can improve the coding performance. A gain about 0.6-0.7dB can be achieved with the same rate in H.264. In addition,it converges as fast as Bisection method,with almost the same complexity.
基金Projects(2013BAB02B01,2013BAB02B03)supported by the National Key Technology R&D Program of ChinaProject(N120801002)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(N20130042110010)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter(d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth(h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.
