Compared to conventional oxidation ditches, an integrated oxidation ditch with vertical circle （IODVC） has the characters of concise configuration, simple operation and maintenance, land saving and automatical sludg...Compared to conventional oxidation ditches, an integrated oxidation ditch with vertical circle （IODVC） has the characters of concise configuration, simple operation and maintenance, land saving and automatical sludge returning. By the utilization of vertical circulation, an aerobic zone and an anoxic zone can be unaffectedly formed in the IODVC. Therefore, COD and nitrogen can be efficiently removed. However, the removal efficiency of phosphorus was low in the IODVC. In the experiment described, a laboratory scale system to add an anaerobic column to the IODVC has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that the removal efficiency of TP with the anaerobic column was increased to 54.0% from 22.3% without the anaerobic column. After the acetic sodium was added into the influent as carbon sources, the mean TP removal efficency of 77. 5 % was obtained. At the same time, the mean removal efficiencies of COD, TN and NH3-N were 92.2%, 81.6% and 98.1%, respectively, at 12 h of HRT and 21-25 d of SRT. The optimal operational conditions in this study were as follows： recycle rate = 1.5-2.0, COD/TN 〉 6, COD/TP 〉 40, COD loading rate = 0.26-0.32 kgCOD/（kgSS· d）, TN loading rate = 0. 028-0. 034 kgTN/（ kgSS·d） and TP loading rate = 0.003-0.005 kgTP/（kgSS· d）, respectively.展开更多
Following the accession to the WTO of China,bank card industry faces new competition pressure and challenges. At present, the most outstanding problem we face is, how to narrow the gap of development between the inter...Following the accession to the WTO of China,bank card industry faces new competition pressure and challenges. At present, the most outstanding problem we face is, how to narrow the gap of development between the international bank card industry and that of China and keep up with fast-developing paces of international bank card as soon as possible. Objectively speaking, bank card industry of our country is still at the initial stage.展开更多
The rocks surrounding a roadway exhibit some special and complex phenomena with increasing depth of excavation in underground engineering.Quasi-static analysis cannot adequately explain these engineering problems.The ...The rocks surrounding a roadway exhibit some special and complex phenomena with increasing depth of excavation in underground engineering.Quasi-static analysis cannot adequately explain these engineering problems.The computational model of a circular roadway considering the transient effect of excavation unloading is established for these problems.The time factor makes the solution of the problem difficult.Thus,the computational model is divided into a dynamic model and a static model.The Laplace integral transform and inverse transform are performed to solve the dynamic model and elasticity theory is used to analyze the static model.The results from an example show that circumferential stress increases and radial stress decreases with time.The stress difference becomes large gradually in this progress.The displacement increases with unloading time and decreases with the radial depth of surrounding rocks.It can be seen that the development trend of unloading and displacement is similar by comparing their rates.Finally,the results of ANSYS are used to verify the analytical solution.The contrast indicates that the laws of the two methods are basically in agreement.Thus,the analysis can provide a reference for further study.展开更多
文摘Compared to conventional oxidation ditches, an integrated oxidation ditch with vertical circle （IODVC） has the characters of concise configuration, simple operation and maintenance, land saving and automatical sludge returning. By the utilization of vertical circulation, an aerobic zone and an anoxic zone can be unaffectedly formed in the IODVC. Therefore, COD and nitrogen can be efficiently removed. However, the removal efficiency of phosphorus was low in the IODVC. In the experiment described, a laboratory scale system to add an anaerobic column to the IODVC has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that the removal efficiency of TP with the anaerobic column was increased to 54.0% from 22.3% without the anaerobic column. After the acetic sodium was added into the influent as carbon sources, the mean TP removal efficency of 77. 5 % was obtained. At the same time, the mean removal efficiencies of COD, TN and NH3-N were 92.2%, 81.6% and 98.1%, respectively, at 12 h of HRT and 21-25 d of SRT. The optimal operational conditions in this study were as follows： recycle rate = 1.5-2.0, COD/TN 〉 6, COD/TP 〉 40, COD loading rate = 0.26-0.32 kgCOD/（kgSS· d）, TN loading rate = 0. 028-0. 034 kgTN/（ kgSS·d） and TP loading rate = 0.003-0.005 kgTP/（kgSS· d）, respectively.
文摘Following the accession to the WTO of China,bank card industry faces new competition pressure and challenges. At present, the most outstanding problem we face is, how to narrow the gap of development between the international bank card industry and that of China and keep up with fast-developing paces of international bank card as soon as possible. Objectively speaking, bank card industry of our country is still at the initial stage.
基金supported by the National Natural Science Foundation of China (Nos.51479108 and 51174196)the National Basic Research Program of China (No.2014CB046300)+1 种基金Shandong University of Science and Technology (No.2012KYTD104)Research Start-up Project of Shandong University of Science and Technology (No.2015RCJJ061)
文摘The rocks surrounding a roadway exhibit some special and complex phenomena with increasing depth of excavation in underground engineering.Quasi-static analysis cannot adequately explain these engineering problems.The computational model of a circular roadway considering the transient effect of excavation unloading is established for these problems.The time factor makes the solution of the problem difficult.Thus,the computational model is divided into a dynamic model and a static model.The Laplace integral transform and inverse transform are performed to solve the dynamic model and elasticity theory is used to analyze the static model.The results from an example show that circumferential stress increases and radial stress decreases with time.The stress difference becomes large gradually in this progress.The displacement increases with unloading time and decreases with the radial depth of surrounding rocks.It can be seen that the development trend of unloading and displacement is similar by comparing their rates.Finally,the results of ANSYS are used to verify the analytical solution.The contrast indicates that the laws of the two methods are basically in agreement.Thus,the analysis can provide a reference for further study.
