The BOD5-DO (Biochemical Oxygen Demand in five days and Dissolved Oxygen) are important indexes that reflect the organic pollution extent of water,but the variation of the indexes is closely related with water tempera...The BOD5-DO (Biochemical Oxygen Demand in five days and Dissolved Oxygen) are important indexes that reflect the organic pollution extent of water,but the variation of the indexes is closely related with water temperature. The study on the coupled mathematical model reflecting the BOD5-DO with temperature is the key to reveal the mechanism of the migration and distribution of BOD5-DO in the water. The authors presented 1-D mathematical model for the three variables in vertical direction,and gave accurate solution for the equations under steady state,the relation among the variables and the method for solving BOD5-DO concentrations at different depth and temperature.展开更多
A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall.The main characteristics of the model include：1） a prototype of the key...A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall.The main characteristics of the model include：1） a prototype of the keyhole and the inverse Bremsstrahlung absorption coefficient in the keyhole plasma are obtained from the experiments;2） instead of using a parallel incident beam,a focused laser beam with real Gaussian intensity distribution is implemented;3） both Fresnel absorption and inverse Bremsstrahlung absorption during multiple reflections are considered.The calculation results show that the distribution of absorbed laser intensity by the keyhole wall is not uniform.The maximum laser energy is absorbed by the bottom of the keyhole,although no rays irradiate directly onto the bottom.According to analysis of beam focusing characteristics,the location of the focal plane plays a more important role in the laser energy absorption by the front wall than by the rear wall.展开更多
Sustained casing pressure （SCP） in gas wells brings a serious threat to worker safety and environmental protection. According to geological conditions, wellbore structure and cement data of gas wells in the Sichuan-...Sustained casing pressure （SCP） in gas wells brings a serious threat to worker safety and environmental protection. According to geological conditions, wellbore structure and cement data of gas wells in the Sichuan-Chongqing region, China, the position, time, environmental condition and the value of SCP have been analyzed. On this basis, the shape of the pressure bleed-down plot and pressure buildup plot were diagnosed and the mechanism of SCP has been clarified. Based on generalized annular Darcy percolation theory and gas-liquid two-phase fluid dynamics theory, a coupled mathematical model of gas migration in a cemented annulus with a mud column above the cement has been developed. The volume of gas migrated in the annulus and the value of SCP changing with time in a gas well in Sichuan have been calculated by this model. Calculation results coincided well with the actual field data, which provide some reference for the following security evaluation and solution measures of SCP.展开更多
文摘The BOD5-DO (Biochemical Oxygen Demand in five days and Dissolved Oxygen) are important indexes that reflect the organic pollution extent of water,but the variation of the indexes is closely related with water temperature. The study on the coupled mathematical model reflecting the BOD5-DO with temperature is the key to reveal the mechanism of the migration and distribution of BOD5-DO in the water. The authors presented 1-D mathematical model for the three variables in vertical direction,and gave accurate solution for the equations under steady state,the relation among the variables and the method for solving BOD5-DO concentrations at different depth and temperature.
基金Projects (51175162, 50805045) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,China
文摘A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall.The main characteristics of the model include：1） a prototype of the keyhole and the inverse Bremsstrahlung absorption coefficient in the keyhole plasma are obtained from the experiments;2） instead of using a parallel incident beam,a focused laser beam with real Gaussian intensity distribution is implemented;3） both Fresnel absorption and inverse Bremsstrahlung absorption during multiple reflections are considered.The calculation results show that the distribution of absorbed laser intensity by the keyhole wall is not uniform.The maximum laser energy is absorbed by the bottom of the keyhole,although no rays irradiate directly onto the bottom.According to analysis of beam focusing characteristics,the location of the focal plane plays a more important role in the laser energy absorption by the front wall than by the rear wall.
基金co-financed by the China National Natural Science Foundation and Shanghai Baosteel Group Corporation (No. 51074135)Program for New Century Excellent Talents in University (No. NCET-08-0907)Jilin Oilfield Company Project (No. JS10-W-14-JZ-32-51)
文摘Sustained casing pressure （SCP） in gas wells brings a serious threat to worker safety and environmental protection. According to geological conditions, wellbore structure and cement data of gas wells in the Sichuan-Chongqing region, China, the position, time, environmental condition and the value of SCP have been analyzed. On this basis, the shape of the pressure bleed-down plot and pressure buildup plot were diagnosed and the mechanism of SCP has been clarified. Based on generalized annular Darcy percolation theory and gas-liquid two-phase fluid dynamics theory, a coupled mathematical model of gas migration in a cemented annulus with a mud column above the cement has been developed. The volume of gas migrated in the annulus and the value of SCP changing with time in a gas well in Sichuan have been calculated by this model. Calculation results coincided well with the actual field data, which provide some reference for the following security evaluation and solution measures of SCP.
