Effect of uniaxial compression on the nucleation of micro-damage in cement mortar under sulfate attack is investigated. Shape and size of micro-voids in cement mortar is detected using Micro Computed Tomography techni...Effect of uniaxial compression on the nucleation of micro-damage in cement mortar under sulfate attack is investigated. Shape and size of micro-voids in cement mortar is detected using Micro Computed Tomography techniques. The formation of delayed ettringite crystal is analyzed using scanning electron microscope and energy disperse spectrum methods. Deformation of micro-voids and the distribution of stress at the surface of a micro-void are calculated. It is found that the nucleation of micro-cracks is caused by the tensile stress at the voids＇ surface, and such damage nucleation will be speeded up by the remote uniaxial compressive load.展开更多
This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite por...This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite porous plate. The heat transfer analysis is carried out for two heating processes. The system of highly non-linear differential equations is solved by the shooting method with the fourth-order Runge-Kutta method for moderate values of the parameters. The effective Broyden technique is adopted in order to improve the initial guesses and to satisfy the boundary conditions at infinity. An exceptional cross-over is obtained in the velocity profile in the presence of slip. The fourth-grade fluid parameter is found to increase the momentum boundary layer thickness, whereas the slip parameter substantially decreases it. Similarly, the non-Newtonian fluid parameters and the slip have opposite effects on the thermal boundary layer thickness.展开更多
Focal region field of a two dimensional Gregorian system coated with chiral medium is analyzed at high frequency. Maslov's method is used because the Geometrical Optics approximation fails at focal points. Maslov...Focal region field of a two dimensional Gregorian system coated with chiral medium is analyzed at high frequency. Maslov's method is used because the Geometrical Optics approximation fails at focal points. Maslov’s method combines the simplicity of ray theory and the generality of Fourier transform. Fields patterns are calculated numerically and the results are plotted. The effects of thickness of chiral layer, chirality parameter of the chiral medium and permittivity of the medium are analyzed. The problem of simple dielectric layer is discussed as a special case of this problem.展开更多
东非某工程堆场面积约为115万m^2,采用港池和泊位吹填料回填至堆场,设计荷载为30 k Pa及50 k Pa。根据咨工要求,在不同设计荷载的区域进行地质钻孔,再通过De Beer’s method公式计算理论沉降量,若此理论沉降量小于10 cm则不需要进行地...东非某工程堆场面积约为115万m^2,采用港池和泊位吹填料回填至堆场,设计荷载为30 k Pa及50 k Pa。根据咨工要求,在不同设计荷载的区域进行地质钻孔,再通过De Beer’s method公式计算理论沉降量,若此理论沉降量小于10 cm则不需要进行地基处理。根据计算结果,部分位置的沉降量极其接近临界值10 cm,如直接判断不需要进行地基处理,则在后续施工或堆场使用过程中可能出现较大沉降。通过区域载荷试验对该理论沉降量进行检验校核,后续计算结果和区域载荷试验显示,堆场均不用进行地基处理。展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 10932001,51079069,10972109,and 10802039)the National Basic Research Program of China (973 Program,No. 2009CB623203)+1 种基金the Ministry of Education of the People’s Republic of China (No. 20103305110001)K.C.Wong Magna Fund in Ningbo University
文摘Effect of uniaxial compression on the nucleation of micro-damage in cement mortar under sulfate attack is investigated. Shape and size of micro-voids in cement mortar is detected using Micro Computed Tomography techniques. The formation of delayed ettringite crystal is analyzed using scanning electron microscope and energy disperse spectrum methods. Deformation of micro-voids and the distribution of stress at the surface of a micro-void are calculated. It is found that the nucleation of micro-cracks is caused by the tensile stress at the voids＇ surface, and such damage nucleation will be speeded up by the remote uniaxial compressive load.
文摘This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite porous plate. The heat transfer analysis is carried out for two heating processes. The system of highly non-linear differential equations is solved by the shooting method with the fourth-order Runge-Kutta method for moderate values of the parameters. The effective Broyden technique is adopted in order to improve the initial guesses and to satisfy the boundary conditions at infinity. An exceptional cross-over is obtained in the velocity profile in the presence of slip. The fourth-grade fluid parameter is found to increase the momentum boundary layer thickness, whereas the slip parameter substantially decreases it. Similarly, the non-Newtonian fluid parameters and the slip have opposite effects on the thermal boundary layer thickness.
文摘Focal region field of a two dimensional Gregorian system coated with chiral medium is analyzed at high frequency. Maslov's method is used because the Geometrical Optics approximation fails at focal points. Maslov’s method combines the simplicity of ray theory and the generality of Fourier transform. Fields patterns are calculated numerically and the results are plotted. The effects of thickness of chiral layer, chirality parameter of the chiral medium and permittivity of the medium are analyzed. The problem of simple dielectric layer is discussed as a special case of this problem.
文摘东非某工程堆场面积约为115万m^2,采用港池和泊位吹填料回填至堆场,设计荷载为30 k Pa及50 k Pa。根据咨工要求,在不同设计荷载的区域进行地质钻孔,再通过De Beer’s method公式计算理论沉降量,若此理论沉降量小于10 cm则不需要进行地基处理。根据计算结果,部分位置的沉降量极其接近临界值10 cm,如直接判断不需要进行地基处理,则在后续施工或堆场使用过程中可能出现较大沉降。通过区域载荷试验对该理论沉降量进行检验校核,后续计算结果和区域载荷试验显示,堆场均不用进行地基处理。
