The rheological characterization of sewage sludge at different steps of wastewater treatment is important since it allows predicting and estimating sludge behavior when submitted to almost all treatment and disposal o...The rheological characterization of sewage sludge at different steps of wastewater treatment is important since it allows predicting and estimating sludge behavior when submitted to almost all treatment and disposal operations. Rotating biological contactor (RBC) is being widely used for wastewater treatment, which is a biological treatment process following primary treatment. The rheological characterization of RBC sludge at different solid contents (TSS = 32.2 g/L–50.2 g/L) and temperatures (5–40 °C) was carried out using a rotational viscometer. The RBC sludge showed a shear-thinning behavior, where the apparent viscosity decreased rapidly with the shear rate reaching the limiting viscosity (n) at the infinite shear rate. An exponential relationship described the evolution of the limiting viscosity with the sludge TSS content. In addition, a dramatic increase in the limiting viscosity beyond a TSS concentration of 42.4 g/L has been observed. On the other hand, Bingham model described well the non-Newtonian behavior of sludge suspensions. It was clear that the yield stress is more sensitive than the Bingham viscosity for the variation in temperature and solid content. However, the rheological results revealed that both the limiting and Bingham viscosities have the same behavior with the TSS content and with the temperature.展开更多
Assessing the slope deformation is significant for landslide prediction. Many researchers have studied the slope displacement based on field data from the inclinometer in combination with complicated numerical analysi...Assessing the slope deformation is significant for landslide prediction. Many researchers have studied the slope displacement based on field data from the inclinometer in combination with complicated numerical analysis. They found that there was a shear zone above the slip surface, and they usually focused on the distribution of velocity and displacement within the shear zone. In this paper,two simple methods are proposed to analyze the distribution of displacement and velocity along the whole profile of a slope from the slip surface to the slope surface during slow movement. In the empirical method, the slope soil above the shear zone is assumed as a rigid body. Dual or triple piecewise fitting functions are empirically proposed for the distribution of velocity along the profile of a slope. In the analytical method, the slope soil is not assumed as a rigid body but as a deformable material. Continuous functions of the velocity and displacement along the profile of a slope are directly obtained by solving the Newton's equation of motion associated with the Bingham model. Using the two proposed methods respectively, the displacement and velocity along the slope profiles of three slopes are determined. A reasonable agreement between the measured data and the calculated results of the two proposed methods has been reached. In comparison with the empirical method, the analytical method would be more beneficial for slope deformation analysis in slope engineering, because the parameters are material constants in the analytical solution independent of time t, and the nonlinear viscosity of the soil can be considered.展开更多
The vibration of a single protein bubble may take place under the action of high pressure difference. In this process, the bubble wall may experience a finite deformation. The equation describing the dynamics of the p...The vibration of a single protein bubble may take place under the action of high pressure difference. In this process, the bubble wall may experience a finite deformation. The equation describing the dynamics of the protein bubble with viscoelastic film in Bingham liquid is derived. A numerical solution to this equation is carried out to study the effect of liquid pressure, the characteristic parameters of Bingham liquid and the viscosity of the protein film on the finite deformation of the bubble. The results show that the vibration of the protein bubble wall is caused by the action of pressure difference, the elastic stress in finite deformation and the dissipation of viscosity of the protein film and Bingham liquid. The vibration is nonlinear. Decreasing the pressure difference between gas and Bingham liquid on both sides of the protein bubble will lead to a change of vibration performance. The frequency and amplitude are reduced, tegether with the speed of vibration damping. In addition, the deformation rate of the bubble is smaller when the amplitude of vibration is reduced, which means shorter time to reach a balance state. On the other side, the increase of the magnitude of viscosity of the protein film or the plastic viscosity of Bingham liquid can restrain the vibration of the protein bubble wall in the course of finite deformation, as a result, the load bearing capacity of bubble is enhanced.展开更多
An attempt is made to analyse some lubrication characteristics of rigid cylindrical asymmetric rollers under adiabatic and isothermal boundaries with rolling and sliding motion lubricated by a non-Newtonian incompress...An attempt is made to analyse some lubrication characteristics of rigid cylindrical asymmetric rollers under adiabatic and isothermal boundaries with rolling and sliding motion lubricated by a non-Newtonian incompressible Bingham plastic fluid under the behaviour of line contact.Here the lower surface is considered to move quicker than that of the upper surface;and the Roelands viscosity model is considered and assumed to depend upon the fluid pressure and the mean film temperature.The governing equations for fluid flow such as equations of motion with continuity and the momentum energy equation are solved using Runge-Kutta forth order and MATLAB is employed to solve these equations.Through graphs and tables for Newtonian and non-Newtonian fluids,the several crucial bearing characteristics including velocity,pressure,viscosity,mean temperature,load and traction are examined and a significant change is observed among them.The findings presented here are qualitatively consistent with the existing literature.展开更多
文摘The rheological characterization of sewage sludge at different steps of wastewater treatment is important since it allows predicting and estimating sludge behavior when submitted to almost all treatment and disposal operations. Rotating biological contactor (RBC) is being widely used for wastewater treatment, which is a biological treatment process following primary treatment. The rheological characterization of RBC sludge at different solid contents (TSS = 32.2 g/L–50.2 g/L) and temperatures (5–40 °C) was carried out using a rotational viscometer. The RBC sludge showed a shear-thinning behavior, where the apparent viscosity decreased rapidly with the shear rate reaching the limiting viscosity (n) at the infinite shear rate. An exponential relationship described the evolution of the limiting viscosity with the sludge TSS content. In addition, a dramatic increase in the limiting viscosity beyond a TSS concentration of 42.4 g/L has been observed. On the other hand, Bingham model described well the non-Newtonian behavior of sludge suspensions. It was clear that the yield stress is more sensitive than the Bingham viscosity for the variation in temperature and solid content. However, the rheological results revealed that both the limiting and Bingham viscosities have the same behavior with the TSS content and with the temperature.
基金supported by the National Natural Science Foundation of China(Grant No.51579167)the Public Non-profit Welfare Project from China Ministry of Water Resources(Grant No.201301022)the Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-rock Dam of the Ministry of Water Resources(Grant No.YK915003)
文摘Assessing the slope deformation is significant for landslide prediction. Many researchers have studied the slope displacement based on field data from the inclinometer in combination with complicated numerical analysis. They found that there was a shear zone above the slip surface, and they usually focused on the distribution of velocity and displacement within the shear zone. In this paper,two simple methods are proposed to analyze the distribution of displacement and velocity along the whole profile of a slope from the slip surface to the slope surface during slow movement. In the empirical method, the slope soil above the shear zone is assumed as a rigid body. Dual or triple piecewise fitting functions are empirically proposed for the distribution of velocity along the profile of a slope. In the analytical method, the slope soil is not assumed as a rigid body but as a deformable material. Continuous functions of the velocity and displacement along the profile of a slope are directly obtained by solving the Newton's equation of motion associated with the Bingham model. Using the two proposed methods respectively, the displacement and velocity along the slope profiles of three slopes are determined. A reasonable agreement between the measured data and the calculated results of the two proposed methods has been reached. In comparison with the empirical method, the analytical method would be more beneficial for slope deformation analysis in slope engineering, because the parameters are material constants in the analytical solution independent of time t, and the nonlinear viscosity of the soil can be considered.
基金supported by the Leading Academic Disciplin Project of Shanghai Municipal Education Commission (Gran No.J50501)
文摘The vibration of a single protein bubble may take place under the action of high pressure difference. In this process, the bubble wall may experience a finite deformation. The equation describing the dynamics of the protein bubble with viscoelastic film in Bingham liquid is derived. A numerical solution to this equation is carried out to study the effect of liquid pressure, the characteristic parameters of Bingham liquid and the viscosity of the protein film on the finite deformation of the bubble. The results show that the vibration of the protein bubble wall is caused by the action of pressure difference, the elastic stress in finite deformation and the dissipation of viscosity of the protein film and Bingham liquid. The vibration is nonlinear. Decreasing the pressure difference between gas and Bingham liquid on both sides of the protein bubble will lead to a change of vibration performance. The frequency and amplitude are reduced, tegether with the speed of vibration damping. In addition, the deformation rate of the bubble is smaller when the amplitude of vibration is reduced, which means shorter time to reach a balance state. On the other side, the increase of the magnitude of viscosity of the protein film or the plastic viscosity of Bingham liquid can restrain the vibration of the protein bubble wall in the course of finite deformation, as a result, the load bearing capacity of bubble is enhanced.
文摘An attempt is made to analyse some lubrication characteristics of rigid cylindrical asymmetric rollers under adiabatic and isothermal boundaries with rolling and sliding motion lubricated by a non-Newtonian incompressible Bingham plastic fluid under the behaviour of line contact.Here the lower surface is considered to move quicker than that of the upper surface;and the Roelands viscosity model is considered and assumed to depend upon the fluid pressure and the mean film temperature.The governing equations for fluid flow such as equations of motion with continuity and the momentum energy equation are solved using Runge-Kutta forth order and MATLAB is employed to solve these equations.Through graphs and tables for Newtonian and non-Newtonian fluids,the several crucial bearing characteristics including velocity,pressure,viscosity,mean temperature,load and traction are examined and a significant change is observed among them.The findings presented here are qualitatively consistent with the existing literature.
