Characteristic finite difference fractional step schemes are put forward. The electric potential equation is described by a seven-point finite difference scheme, and the electron and hole concentration equations are t...Characteristic finite difference fractional step schemes are put forward. The electric potential equation is described by a seven-point finite difference scheme, and the electron and hole concentration equations are treated by a kind of characteristic finite difference fractional step methods. The temperature equation is described by a fractional step method. Thick and thin grids are made use of to form a complete set. Piecewise threefold quadratic interpolation, symmetrical extension, calculus of variations, commutativity of operator product, decomposition of high order difference operators and prior estimates are also made use of. Optimal order estimates in l2 norm are derived to determine the error of the approximate solution. The well-known problem is thorongley and completely solred.展开更多
This article discusses the enhanced oil recovery numerical simulation of the chemical-flooding (such as surfactallts, alcohol, polymers) composed of three-dimensional multicomponent, multiphase and incompressible mixe...This article discusses the enhanced oil recovery numerical simulation of the chemical-flooding (such as surfactallts, alcohol, polymers) composed of three-dimensional multicomponent, multiphase and incompressible mixed fluids. The mathematical model can be described as a coupled system of nonlinear partial differential equations with initialboundary value problerns. viom the actual conditions such as the effect of cross interference and the three-dimensional charederistic of large-scale science-engineering computation,this article puts forward a kind of characteristic finite element fractional step schemes and obtain the optimal order error estdriates in L2 norm. Thus we have thoroughly solved the well-known theoretical problem proppsed by a famous scientist, R. E. Ewing.展开更多
The correlated Levy flight is studied analytically in terms of the fractional Fokker-Planck equation and simulated numerically by using the Langevin equation, where the usual white Ltvy noise is generalized to an Orns...The correlated Levy flight is studied analytically in terms of the fractional Fokker-Planck equation and simulated numerically by using the Langevin equation, where the usual white Ltvy noise is generalized to an Ornstein-Uhlenbeck Levy process （OALP） with a correlation time τc. We analyze firstly the stable behavior of OULP. The probability density function of Ltvy flight particle driven by the OULP in a harmonic potential is exactly obtained, which is also a Ltvy-type one with Tc-dependence width; when the particle is bounded by a quartic potential, its stationary distribution has a bimodality shape and becomes noticeable with the increase of τc.展开更多
The disease burden of hepatocellular carcinoma (HCC) in China is heavy, and the prognosis is stillunfavourable. Therefore, early screening of high-risk groups of HCC through simple methods is the key toachieving early...The disease burden of hepatocellular carcinoma (HCC) in China is heavy, and the prognosis is stillunfavourable. Therefore, early screening of high-risk groups of HCC through simple methods is the key toachieving early diagnosis and treatment and improving survival. At present, alpha-fetoprotein and otherhematological tests are still the main methods in the early screening of HCC, but the sensitivity andspecificity are limited, and the risk of missed diagnosis is high. In recent years, with the continuousdevelopment of science and technology, the improvement of traditional detection methods and theemergence of novel markers such as methylated deoxyribonucleic acid and microRNA have brought hopefor further improving the sensitivity and specificity of early HCC screening. This consensus summarizesthe research progress of traditional and new hematological test methods and puts forward expertguidance on the role of hematological markers in the early screening of HCC to provide a basis forimproving the prevention and control level in China.展开更多
基金This work is supported by the Major State Basic Research Program of China (19990328), the National Tackling Key Problem Program, the National Science Foundation of China (10271066 and 0372052), and the Doctorate Foundation of the Ministry of Education of China (20030422047).
文摘Characteristic finite difference fractional step schemes are put forward. The electric potential equation is described by a seven-point finite difference scheme, and the electron and hole concentration equations are treated by a kind of characteristic finite difference fractional step methods. The temperature equation is described by a fractional step method. Thick and thin grids are made use of to form a complete set. Piecewise threefold quadratic interpolation, symmetrical extension, calculus of variations, commutativity of operator product, decomposition of high order difference operators and prior estimates are also made use of. Optimal order estimates in l2 norm are derived to determine the error of the approximate solution. The well-known problem is thorongley and completely solred.
文摘This article discusses the enhanced oil recovery numerical simulation of the chemical-flooding (such as surfactallts, alcohol, polymers) composed of three-dimensional multicomponent, multiphase and incompressible mixed fluids. The mathematical model can be described as a coupled system of nonlinear partial differential equations with initialboundary value problerns. viom the actual conditions such as the effect of cross interference and the three-dimensional charederistic of large-scale science-engineering computation,this article puts forward a kind of characteristic finite element fractional step schemes and obtain the optimal order error estdriates in L2 norm. Thus we have thoroughly solved the well-known theoretical problem proppsed by a famous scientist, R. E. Ewing.
基金supported by the National Natural Science Foundation of China(Grant Nos.61178067,10875013 and 11175021)the Doctoral Scientific Research Starting Foundation of Taiyuan University of Science and Technology(Grant No.20122042)
文摘The correlated Levy flight is studied analytically in terms of the fractional Fokker-Planck equation and simulated numerically by using the Langevin equation, where the usual white Ltvy noise is generalized to an Ornstein-Uhlenbeck Levy process （OALP） with a correlation time τc. We analyze firstly the stable behavior of OULP. The probability density function of Ltvy flight particle driven by the OULP in a harmonic potential is exactly obtained, which is also a Ltvy-type one with Tc-dependence width; when the particle is bounded by a quartic potential, its stationary distribution has a bimodality shape and becomes noticeable with the increase of τc.
文摘The disease burden of hepatocellular carcinoma (HCC) in China is heavy, and the prognosis is stillunfavourable. Therefore, early screening of high-risk groups of HCC through simple methods is the key toachieving early diagnosis and treatment and improving survival. At present, alpha-fetoprotein and otherhematological tests are still the main methods in the early screening of HCC, but the sensitivity andspecificity are limited, and the risk of missed diagnosis is high. In recent years, with the continuousdevelopment of science and technology, the improvement of traditional detection methods and theemergence of novel markers such as methylated deoxyribonucleic acid and microRNA have brought hopefor further improving the sensitivity and specificity of early HCC screening. This consensus summarizesthe research progress of traditional and new hematological test methods and puts forward expertguidance on the role of hematological markers in the early screening of HCC to provide a basis forimproving the prevention and control level in China.
