A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styren...A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styrene/Cu （ABS/Cu） gradient polymeric composites were prepared successfully using this technique. The gradient structures, electrically conductive performance and mechanical properties of the ABS/Cu composites were investigated. Optical microscope observation shows that the gradient distribution of Cu particles in ABS matrix was formed along their thickness-direction. The electrically conductive testing results indicate that the order of magnitude of surface resistivity was kept in 10^15 Ω at ABS rich side, while that declined to 10^5 Ω at Cu particles rich side, and the percolation threshold was in the range of 2.82 vo1%- 4.74 vol% Cu content at Cu particles rich side. Mechanical test shows that the tensile strength reduced insignificantly as the content of Cu increases owing to the gradient distribution.展开更多
We investigate the low Mach number limit for the isentropic compressible NavierStokes equations with a revised Maxwell's law(with Galilean invariance) in R^(3). By applying the uniform estimates of the error syste...We investigate the low Mach number limit for the isentropic compressible NavierStokes equations with a revised Maxwell's law(with Galilean invariance) in R^(3). By applying the uniform estimates of the error system, it is proven that the solutions of the isentropic Navier-Stokes equations with a revised Maxwell's law converge to that of the incompressible Navier-Stokes equations as the Mach number tends to zero. Moreover, the convergence rates are also obtained.展开更多
Through the estimates for Greens function of linearized system, we obtain L p estimates of the asymptotic behavior of solutions of the Cauchy problem for the Navier Stokes systems of compressible flow in seve...Through the estimates for Greens function of linearized system, we obtain L p estimates of the asymptotic behavior of solutions of the Cauchy problem for the Navier Stokes systems of compressible flow in several space dimensions.展开更多
By combining Chapman-Enskog expansion with the BGK approximation to Baltzmann equation and Navier-Stokes equation was obtained. And an expression of (Darcy's) law was obtained through taking variable average over ...By combining Chapman-Enskog expansion with the BGK approximation to Baltzmann equation and Navier-Stokes equation was obtained. And an expression of (Darcy's) law was obtained through taking variable average over Navier-Stokes equation on some representative space in porous media,and finally an example was taken to prove its reliability.展开更多
Considering that thermodynarmic irreversibility and hydrodynamic equations can not be derived rigorously and unifiedly from the Liouville equations, the anomalous Langevin equation in the Liouville space is proposed a...Considering that thermodynarmic irreversibility and hydrodynamic equations can not be derived rigorously and unifiedly from the Liouville equations, the anomalous Langevin equation in the Liouville space is proposed as a fundamental equation of statistical physics. This equation reflects that the law of motion of particles obeying reversible, deterministic laws in dynamics becomes irreversible and stochastic in thermodynamics. From this the fundamental equations of nonequilibrium thermodynamics, the principle of entropy increase and the theorem of minimum entropy production have been derived. The hydrodynamic equations, such as the generalized Navier-Stokes equation and the mass drift-diffusion equation etc. have been derived rigorously from the kinetic kinetic equation which is reduced from the anomalous Langevin equation in Liouville space. All these are unified and self consistent. But it is difficult to prove that entropy production density σ can never be negative everywhere for all the isolated inhomogeneous systems far from equilibrium.展开更多
The solid-liquid separation is an important operation for the regenerated slurry of dual-alkali FGD system,and calcium sulfite could predominate in particle aggregates of the slurry.The settling velocity of calcium su...The solid-liquid separation is an important operation for the regenerated slurry of dual-alkali FGD system,and calcium sulfite could predominate in particle aggregates of the slurry.The settling velocity of calcium sulfite particles is a key parameter for the solid-liquid separation design.However,the settling velocity predicted by Stokes' Law could be suitable only for a spherical aggregate, but not for the irregular one.In this work,fractal geometry was introduced in order to characterize highly irregular geometric shapes.The sizes of calcium sulfite particle aggregates were analyzed using a metallographic phase microscope and image analysis.The results showed that particle aggregates had fractal features.The fractal dimensions could reveal the characteristics of the aggregates' geometry and aggregation process.An exponential relation between the fractal dimension D_2 and the particle size l was determined as A∝l^(D2). According to fractal theory,a parameter can be used to modify Stokes settling velocity close to actual settling velocity.The results could be valuable for the design of solid-liquid separation processes.展开更多
基金Funded by the National Natural Science Foundation of China(No.21274007)the Beijing Natural Science Foundation+1 种基金the Key Scientific Project of Beijing Municipal Education Commission(No.KZ201110011014)the Science and Technology Innovation Platform of Beijing Municipal Education Commission(No.PXM2012-014213-000025)
文摘A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styrene/Cu （ABS/Cu） gradient polymeric composites were prepared successfully using this technique. The gradient structures, electrically conductive performance and mechanical properties of the ABS/Cu composites were investigated. Optical microscope observation shows that the gradient distribution of Cu particles in ABS matrix was formed along their thickness-direction. The electrically conductive testing results indicate that the order of magnitude of surface resistivity was kept in 10^15 Ω at ABS rich side, while that declined to 10^5 Ω at Cu particles rich side, and the percolation threshold was in the range of 2.82 vo1%- 4.74 vol% Cu content at Cu particles rich side. Mechanical test shows that the tensile strength reduced insignificantly as the content of Cu increases owing to the gradient distribution.
基金Yuxi HU was supported by the NNSFC (11701556)the Yue Qi Young Scholar ProjectChina University of Mining and Technology (Beijing)。
文摘We investigate the low Mach number limit for the isentropic compressible NavierStokes equations with a revised Maxwell's law(with Galilean invariance) in R^(3). By applying the uniform estimates of the error system, it is proven that the solutions of the isentropic Navier-Stokes equations with a revised Maxwell's law converge to that of the incompressible Navier-Stokes equations as the Mach number tends to zero. Moreover, the convergence rates are also obtained.
文摘Through the estimates for Greens function of linearized system, we obtain L p estimates of the asymptotic behavior of solutions of the Cauchy problem for the Navier Stokes systems of compressible flow in several space dimensions.
文摘By combining Chapman-Enskog expansion with the BGK approximation to Baltzmann equation and Navier-Stokes equation was obtained. And an expression of (Darcy's) law was obtained through taking variable average over Navier-Stokes equation on some representative space in porous media,and finally an example was taken to prove its reliability.
文摘Considering that thermodynarmic irreversibility and hydrodynamic equations can not be derived rigorously and unifiedly from the Liouville equations, the anomalous Langevin equation in the Liouville space is proposed as a fundamental equation of statistical physics. This equation reflects that the law of motion of particles obeying reversible, deterministic laws in dynamics becomes irreversible and stochastic in thermodynamics. From this the fundamental equations of nonequilibrium thermodynamics, the principle of entropy increase and the theorem of minimum entropy production have been derived. The hydrodynamic equations, such as the generalized Navier-Stokes equation and the mass drift-diffusion equation etc. have been derived rigorously from the kinetic kinetic equation which is reduced from the anomalous Langevin equation in Liouville space. All these are unified and self consistent. But it is difficult to prove that entropy production density σ can never be negative everywhere for all the isolated inhomogeneous systems far from equilibrium.
基金Supported by the National Hi-tech Research and Development Program (863 Program) of China (No.2001AA642030-1)New Century Excellent Scholar Program of Ministry of Education of China (No.NCET-04-0549)The Key Research Project of Zhejiang Province (No.010007037)
文摘The solid-liquid separation is an important operation for the regenerated slurry of dual-alkali FGD system,and calcium sulfite could predominate in particle aggregates of the slurry.The settling velocity of calcium sulfite particles is a key parameter for the solid-liquid separation design.However,the settling velocity predicted by Stokes' Law could be suitable only for a spherical aggregate, but not for the irregular one.In this work,fractal geometry was introduced in order to characterize highly irregular geometric shapes.The sizes of calcium sulfite particle aggregates were analyzed using a metallographic phase microscope and image analysis.The results showed that particle aggregates had fractal features.The fractal dimensions could reveal the characteristics of the aggregates' geometry and aggregation process.An exponential relation between the fractal dimension D_2 and the particle size l was determined as A∝l^(D2). According to fractal theory,a parameter can be used to modify Stokes settling velocity close to actual settling velocity.The results could be valuable for the design of solid-liquid separation processes.
