Bio-electrochemical system( BES) was used to soften hard water,and effects of ion species,electrode area and influent concentration on the performance of BES to soften hard water were analyzed. The results showed that...Bio-electrochemical system( BES) was used to soften hard water,and effects of ion species,electrode area and influent concentration on the performance of BES to soften hard water were analyzed. The results showed that it was more easy to remove Mg^(2+) from the hard water than Ca^(2+). Increasing electrode area could enhance the performance of BES to soften hard water. When the amount of added graphite at the anode was 150 g,the removal efficiency of Ca^(2+) increased by 18. 1%. The increase of influent concentration at the anode and the cathode could improve the softening efficiency of hard water by BES. As COD concentration at the anode and NO_3^--N concentration at the cathode increased to 2000 and 300 mg/L,the removal efficiency of Ca^(2+) rose by 36. 1% and 9. 4% respectively.展开更多
The closed form solutions of the stress and displacement in strain softening rock mass around a newly formed cavity are derived with a three step-wise elasto-plastic model. Hoek-Brown criterion is adopted as the yield...The closed form solutions of the stress and displacement in strain softening rock mass around a newly formed cavity are derived with a three step-wise elasto-plastic model. Hoek-Brown criterion is adopted as the yielding criterion of rock mass. Damage factors are proposed to account for degradation of the material parameters to reflect the degree of strain softening. The surrounding rock mass around the cavity is divided into three regions: elastic region, strain softening region and residual state region. The analytical solutions of stress, strain, displacement and radius of each region are obtained. The effects of the strain softening and shear dilatancy behavior on the results are investigated with parametric studies. The results show that the radii of the residual state region and strain softening region in the surrounding rock mass with higher damage degree are larger. The radii of the residual state region and strain softening region are 1-2 times and 1.5-3 times of the cavity radius, respectively. The radial and tangential stresses decrease with the increase of the damage factor. The displacement of the cavity wall for the case with maximum plastic bulk strain is nearly twice than that with no dilation. Rock mass moves more toward the center for the case with larger damage factor and shear dilation. The area of the plastic region is larger when the damage factors are considered. The displacements in the surrounding rock mass increase with the increase of the damage factors and shear dilation factors. The solutions can be applied to the stability analysis and support design of the underground excavation.展开更多
基金Supported by National Undergraduate Training Programs for Innovation and Entrepreneurship(201610449064)A Project of Shandong Province Higher Educational Science and Technology Program(J16LD03)+1 种基金Doctoral Scientific Research Foundation of Binzhou University(2014Y17)Natural Science Foundation of Shandong Province(ZR2014EEP009)
文摘Bio-electrochemical system( BES) was used to soften hard water,and effects of ion species,electrode area and influent concentration on the performance of BES to soften hard water were analyzed. The results showed that it was more easy to remove Mg^(2+) from the hard water than Ca^(2+). Increasing electrode area could enhance the performance of BES to soften hard water. When the amount of added graphite at the anode was 150 g,the removal efficiency of Ca^(2+) increased by 18. 1%. The increase of influent concentration at the anode and the cathode could improve the softening efficiency of hard water by BES. As COD concentration at the anode and NO_3^--N concentration at the cathode increased to 2000 and 300 mg/L,the removal efficiency of Ca^(2+) rose by 36. 1% and 9. 4% respectively.
基金Project(11102219) supported by the National Natural Science Foundation of ChinaProject(2013CB036405) supported by the National Basic Research Program of China
文摘The closed form solutions of the stress and displacement in strain softening rock mass around a newly formed cavity are derived with a three step-wise elasto-plastic model. Hoek-Brown criterion is adopted as the yielding criterion of rock mass. Damage factors are proposed to account for degradation of the material parameters to reflect the degree of strain softening. The surrounding rock mass around the cavity is divided into three regions: elastic region, strain softening region and residual state region. The analytical solutions of stress, strain, displacement and radius of each region are obtained. The effects of the strain softening and shear dilatancy behavior on the results are investigated with parametric studies. The results show that the radii of the residual state region and strain softening region in the surrounding rock mass with higher damage degree are larger. The radii of the residual state region and strain softening region are 1-2 times and 1.5-3 times of the cavity radius, respectively. The radial and tangential stresses decrease with the increase of the damage factor. The displacement of the cavity wall for the case with maximum plastic bulk strain is nearly twice than that with no dilation. Rock mass moves more toward the center for the case with larger damage factor and shear dilation. The area of the plastic region is larger when the damage factors are considered. The displacements in the surrounding rock mass increase with the increase of the damage factors and shear dilation factors. The solutions can be applied to the stability analysis and support design of the underground excavation.
