Let u(z) be a real_valued harmonic function in the unit disk, we say u(z)∈h p(1【p【+∞), if the p _mean M p(r,u)=12π∫ 2π 0|u(re i θ )| p d θ 1/p is bounded. M.Riesz showed ...Let u(z) be a real_valued harmonic function in the unit disk, we say u(z)∈h p(1【p【+∞), if the p _mean M p(r,u)=12π∫ 2π 0|u(re i θ )| p d θ 1/p is bounded. M.Riesz showed that if u(z)∈h p(1【p【+∞), then there exists a constant A p, depending only on p such that M p(r,v)≤A pM p(r,u), where v(z) is the conjugate harmonic function of u(z).When v(0)=0 and 1【p≤2, W.K.Hayman showed that A p can be given by pp-1 1/p . First, this paper shows that the constant pp-1 1/p can be changed by a smaller constant pp-1 2/p -1 1/2 . Next, if 1【p≤2, then there exists a constant θ 0∈2-p2pπ,π2p such that M p p(r,v)≤ Im p sin pπ2+ tg pπ2pM p p(r,u) for any analytic function f(z)=u(z)+ i v(z) in the unit disk, whenever -θ 0【 arg f(z)【π2.展开更多
In this paper, we propose a compound algorithm for the image restoration. The algorithm is a convex combination of the ROF model and the LLT model with a parameter function 0. The numerical experiments demonstrate tha...In this paper, we propose a compound algorithm for the image restoration. The algorithm is a convex combination of the ROF model and the LLT model with a parameter function 0. The numerical experiments demonstrate that our compound algorithm is efficient and preserves the main advantages of the two models. In particular, the errors of the compound algorithm in L2 norm between the exact images and corresponding restored images are the smallest among the three models. For images with strong noises, the restored images of the compound algorithm are the best in the corresponding restored images. The proposed algorithm combines the fixed point method, an improved AMG method and the Krylov acceleration. It is found that the combination of these methods is efficient and robust in the image restoration.展开更多
The vapor-liquid equilibrium(VLE) properties for the binary and ternary mixtures of CH4,C2H4 and isoC4H10 are of great importance in the recovery of ethylene from mixture containing CH4 and C2H4 with iso-C4H10 as solv...The vapor-liquid equilibrium(VLE) properties for the binary and ternary mixtures of CH4,C2H4 and isoC4H10 are of great importance in the recovery of ethylene from mixture containing CH4 and C2H4 with iso-C4H10 as solvent.Hence,Gibbs ensemble Monte Carlo(GEMC) simulations were used to estimate vapor-liquid equilibrium for the binary and ternary mixtures of CH4,C2H4 and iso-C4H10 with the united atom potential NERD model.The selected simulation conditions are based on the experiment in the literature.The results of this work were shown to be in satisfactory agreement with available experimental data and predictions of Peng-Robinson equation of state.The structure of simulated liquid phase is also characterized by radial distribution function(RDF),which contributes to further understanding of the VLE curve of these systems.RDF is not sensitive to the pressure and temperature range.With the increase of pressure or the decrease of temperature,the molecules tend to gather together.展开更多
This study examines the hydrodynamic performance of multiple-row vertical slotted breakwaters. We developed a mathematical model based on an eigenfunction expansion method and a least squares technique for Stokes seco...This study examines the hydrodynamic performance of multiple-row vertical slotted breakwaters. We developed a mathematical model based on an eigenfunction expansion method and a least squares technique for Stokes second-order waves. The numerical results obtained for limiting cases of double-row and triple-row walls are in good agreement with results of previous studies and experimental results. Comparisons with experimental measurements of the reflection, transmission, and dissipation coefficients （CR, Cr, and CE） for double-row walls show that the proposed mathematical model adequately reproduces most of the important features. We found that for double-row walls, the CR increases with increasing wave number, kd, and with a decreasing permeable wall part, din. The Cr follows the opposite trend. The CE slowly increases with an increasing kd for lower kd values, reaches a maximum, and then decreases again. In addition, an increasing porosity of dm would significantly decrease the CR while increasing the Cr. At lower values of kd, a decreasing porosity increases the CE, but for high values of kd, a decreasing porosity reduces the Ce. The numerical results indicate that, for triple-row walls, the effect of the arrangement of the chamber widths on hydrodynamic characteristics is not significant, except when kd〈0.5 Double-row slotted breakwaters may exhibit a good wave-absorbing performance at kd〉0.5, where by the horizontal wave force may be smaller than that of a single wall. On the other hand, the difference between double-row and triple-row vertical slotted breakwaters is marginal.展开更多
The ash contents in coal particles were examined in the paper dependably on particle size and its density. So, the two-dimensional regressive function Z = Z（P, D） was the searched object, where Z is random variable ...The ash contents in coal particles were examined in the paper dependably on particle size and its density. So, the two-dimensional regressive function Z = Z（P, D） was the searched object, where Z is random variable describing ash contents, P---density and D---particle diameter. This dependence was determined based on experimental data concerning the coal of type 31. For this coal, the method of ordinary kriging was applied to calculate the values of random variable Z. This method required the proper selection of so-called variogram function, in which four forms were considered in this paper in purpose to select the best solution. The given results were then evaluated by the mean standard error value and compared with empirical data.展开更多
In order to investigate the compression creep of two kinds of high-performance concrete mixtures used for prestressed members in a bridge,an experimental test under laboratory conditions was carried out.Based on the e...In order to investigate the compression creep of two kinds of high-performance concrete mixtures used for prestressed members in a bridge,an experimental test under laboratory conditions was carried out.Based on the experimental results,a power exponent function was used to model the creep degree of these high-performance concretes(HPCs) for structural numerical analysis,and two series parameters of this function for the HPCs were given with the optimum method of evolution program.The experimental data were compared with CEB-FIP 90 and ACI 92 models.Results show that the two code models both overestimate the creep degree of two HPCs,so it is recommended that the power exponent function should be used for the creep analysis of bridge structure.展开更多
We introduce a first-principles density-functional theory,i.e.the finite-difference pseudopotential density- functional theory in real space and the Langevin molecular dynamics annealing technique,to the descriptions ...We introduce a first-principles density-functional theory,i.e.the finite-difference pseudopotential density- functional theory in real space and the Langevin molecular dynamics annealing technique,to the descriptions of structures and some properties of small carbon clusters(C_N,N=2～8).It is shown that the odd-numbered clusters have linear structures and most of the even-numbered clusters prefer cyclic structures.展开更多
Based on the transverse Ising model and using decoupling approximation to the Fermi-type Green＇s function, we study the phase transition properties of the epitaxial ferroeleetric film with one substrate. A general re...Based on the transverse Ising model and using decoupling approximation to the Fermi-type Green＇s function, we study the phase transition properties of the epitaxial ferroeleetric film with one substrate. A general recursive equation of the ferroelectric thin film with two n-layer materials is obtained, which enables us to study the phase transition properties for any number layers for epitaxial ferroelectric thin film. With the help of this equation, we analyze the effect of the exchange interaction and the transverse field in the phase diagram, the influence to the polarizations and Curie temperature numerically. The results show that epitaxial ferroelectric film are able to induce a strong increase or decrease of Curie temperature to different exchange interactions and transverse fields within the epitaxial film layers. The theoretical results are in reasonable accordance with experimental data of different ferroelectric thin film.展开更多
In this paper,a residual type of a posteriori error estimator for the general second order elliptic eigenpair approximation by the mixed finite element method is derived and analyzed,based on a type of superconvergenc...In this paper,a residual type of a posteriori error estimator for the general second order elliptic eigenpair approximation by the mixed finite element method is derived and analyzed,based on a type of superconvergence result of the eigenfunction approximation.Its efficiency and reliability are proved by both theoretical analysis and numerical experiments.展开更多
The authors obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation:αu/αt=△u-b(x,t)u~σ on complete noncompact manifolds with Ricci curvature bounded from below,where 0&...The authors obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation:αu/αt=△u-b(x,t)u~σ on complete noncompact manifolds with Ricci curvature bounded from below,where 0<σ<1 is a real constant,and b(x,t) is a function which is C^2 in the x-variable and C^1 in the t-variable.展开更多
文摘Let u(z) be a real_valued harmonic function in the unit disk, we say u(z)∈h p(1【p【+∞), if the p _mean M p(r,u)=12π∫ 2π 0|u(re i θ )| p d θ 1/p is bounded. M.Riesz showed that if u(z)∈h p(1【p【+∞), then there exists a constant A p, depending only on p such that M p(r,v)≤A pM p(r,u), where v(z) is the conjugate harmonic function of u(z).When v(0)=0 and 1【p≤2, W.K.Hayman showed that A p can be given by pp-1 1/p . First, this paper shows that the constant pp-1 1/p can be changed by a smaller constant pp-1 2/p -1 1/2 . Next, if 1【p≤2, then there exists a constant θ 0∈2-p2pπ,π2p such that M p p(r,v)≤ Im p sin pπ2+ tg pπ2pM p p(r,u) for any analytic function f(z)=u(z)+ i v(z) in the unit disk, whenever -θ 0【 arg f(z)【π2.
基金suppprt from NSFC of China,Singapore NTU project SUG 20/07,MOE Grant T207B2202NRF2007IDMIDM002-010
文摘In this paper, we propose a compound algorithm for the image restoration. The algorithm is a convex combination of the ROF model and the LLT model with a parameter function 0. The numerical experiments demonstrate that our compound algorithm is efficient and preserves the main advantages of the two models. In particular, the errors of the compound algorithm in L2 norm between the exact images and corresponding restored images are the smallest among the three models. For images with strong noises, the restored images of the compound algorithm are the best in the corresponding restored images. The proposed algorithm combines the fixed point method, an improved AMG method and the Krylov acceleration. It is found that the combination of these methods is efficient and robust in the image restoration.
基金Supported by the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(No.IRT0936)National Basic Research Program of China("973"Program,No.2009CB219905 and No.2009CB219907)
文摘The vapor-liquid equilibrium(VLE) properties for the binary and ternary mixtures of CH4,C2H4 and isoC4H10 are of great importance in the recovery of ethylene from mixture containing CH4 and C2H4 with iso-C4H10 as solvent.Hence,Gibbs ensemble Monte Carlo(GEMC) simulations were used to estimate vapor-liquid equilibrium for the binary and ternary mixtures of CH4,C2H4 and iso-C4H10 with the united atom potential NERD model.The selected simulation conditions are based on the experiment in the literature.The results of this work were shown to be in satisfactory agreement with available experimental data and predictions of Peng-Robinson equation of state.The structure of simulated liquid phase is also characterized by radial distribution function(RDF),which contributes to further understanding of the VLE curve of these systems.RDF is not sensitive to the pressure and temperature range.With the increase of pressure or the decrease of temperature,the molecules tend to gather together.
文摘This study examines the hydrodynamic performance of multiple-row vertical slotted breakwaters. We developed a mathematical model based on an eigenfunction expansion method and a least squares technique for Stokes second-order waves. The numerical results obtained for limiting cases of double-row and triple-row walls are in good agreement with results of previous studies and experimental results. Comparisons with experimental measurements of the reflection, transmission, and dissipation coefficients （CR, Cr, and CE） for double-row walls show that the proposed mathematical model adequately reproduces most of the important features. We found that for double-row walls, the CR increases with increasing wave number, kd, and with a decreasing permeable wall part, din. The Cr follows the opposite trend. The CE slowly increases with an increasing kd for lower kd values, reaches a maximum, and then decreases again. In addition, an increasing porosity of dm would significantly decrease the CR while increasing the Cr. At lower values of kd, a decreasing porosity increases the CE, but for high values of kd, a decreasing porosity reduces the Ce. The numerical results indicate that, for triple-row walls, the effect of the arrangement of the chamber widths on hydrodynamic characteristics is not significant, except when kd〈0.5 Double-row slotted breakwaters may exhibit a good wave-absorbing performance at kd〉0.5, where by the horizontal wave force may be smaller than that of a single wall. On the other hand, the difference between double-row and triple-row vertical slotted breakwaters is marginal.
文摘The ash contents in coal particles were examined in the paper dependably on particle size and its density. So, the two-dimensional regressive function Z = Z（P, D） was the searched object, where Z is random variable describing ash contents, P---density and D---particle diameter. This dependence was determined based on experimental data concerning the coal of type 31. For this coal, the method of ordinary kriging was applied to calculate the values of random variable Z. This method required the proper selection of so-called variogram function, in which four forms were considered in this paper in purpose to select the best solution. The given results were then evaluated by the mean standard error value and compared with empirical data.
文摘In order to investigate the compression creep of two kinds of high-performance concrete mixtures used for prestressed members in a bridge,an experimental test under laboratory conditions was carried out.Based on the experimental results,a power exponent function was used to model the creep degree of these high-performance concretes(HPCs) for structural numerical analysis,and two series parameters of this function for the HPCs were given with the optimum method of evolution program.The experimental data were compared with CEB-FIP 90 and ACI 92 models.Results show that the two code models both overestimate the creep degree of two HPCs,so it is recommended that the power exponent function should be used for the creep analysis of bridge structure.
基金The project supported by National Natural Science Foundation of China under Grant No.10274055the Research Fund for the Doctoral Program of High Education of China under Grant No.20020610001
文摘We introduce a first-principles density-functional theory,i.e.the finite-difference pseudopotential density- functional theory in real space and the Langevin molecular dynamics annealing technique,to the descriptions of structures and some properties of small carbon clusters(C_N,N=2～8).It is shown that the odd-numbered clusters have linear structures and most of the even-numbered clusters prefer cyclic structures.
基金Supported partly by SRF for ROCS,SEM under Grant No.20071108
文摘Based on the transverse Ising model and using decoupling approximation to the Fermi-type Green＇s function, we study the phase transition properties of the epitaxial ferroeleetric film with one substrate. A general recursive equation of the ferroelectric thin film with two n-layer materials is obtained, which enables us to study the phase transition properties for any number layers for epitaxial ferroelectric thin film. With the help of this equation, we analyze the effect of the exchange interaction and the transverse field in the phase diagram, the influence to the polarizations and Curie temperature numerically. The results show that epitaxial ferroelectric film are able to induce a strong increase or decrease of Curie temperature to different exchange interactions and transverse fields within the epitaxial film layers. The theoretical results are in reasonable accordance with experimental data of different ferroelectric thin film.
基金supported by National Natural Science Foundation of China(Grant Nos.11001259,11031006,11071265,11201501 and 91230110)National Basic Research Program of China(973 Project)(Grant No. 2011CB309703)+3 种基金International S&T Cooperation Program of China(Grant No. 2010DFR00700)Croucher Foundation of Hong Kong Baptist Universitythe National Center for Mathematics and Interdisciplinary Science,CAS,the President Foundation of AMSS-CASthe Fundamental Research Funds for the CentralUniversities(Grant No. 2012121003)
文摘In this paper,a residual type of a posteriori error estimator for the general second order elliptic eigenpair approximation by the mixed finite element method is derived and analyzed,based on a type of superconvergence result of the eigenfunction approximation.Its efficiency and reliability are proved by both theoretical analysis and numerical experiments.
基金supported by the Jiangsu Provincial Natural Science Foundation of China(No.BK20140804)the Fundamental Research Funds of the Central Universities(No.NS2014076)
文摘The authors obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation:αu/αt=△u-b(x,t)u~σ on complete noncompact manifolds with Ricci curvature bounded from below,where 0<σ<1 is a real constant,and b(x,t) is a function which is C^2 in the x-variable and C^1 in the t-variable.
