In order to improve nitrogen removal in anoxic/oxic(A/O) process effectively for treating domestic wastewaters, the influence factors, DO(dissolved oxygen), nitrate recirculation, sludge recycle, SRT(solids residence ...In order to improve nitrogen removal in anoxic/oxic(A/O) process effectively for treating domestic wastewaters, the influence factors, DO(dissolved oxygen), nitrate recirculation, sludge recycle, SRT(solids residence time), influent COD/TN and HRT(hydraulic retention time) were studied. Results indicated that it was possible to increase nitrogen removal by using corresponding control strategies, such as, adjusting the DO set point according to effluent ammonia concentration; manipulating nitrate recirculation flow according to nitrate concentration at the end of anoxic zone. Based on the experiments results, a knowledge-based approach for supervision of the nitrogen removal problems was considered, and decision trees for diagnosing nitrification and denitrification problems were built and successfully applied to A/O process.展开更多
The manufacturing accuracy of ultra-precision master gears signifies the technological capability of the ultra-precision gear.Currently,there is little report about the manufacturing technologies of ultra-precision ma...The manufacturing accuracy of ultra-precision master gears signifies the technological capability of the ultra-precision gear.Currently,there is little report about the manufacturing technologies of ultra-precision master gears at home and aboard.In order to meet the requirement of grinding ultra precision master gear,the gear grinder with flat-faced wheel Y7125 is chosen as the object machine tool and the geometric model of its precision generating part,the involute cam,is established.According to the structure of the involute cam,the effective working section and its adjustable range of the cam are determined,and the mathematical expressions of the effects of comprehensive eccentricity of the involute cam on gear profile deviations are derived.According to the primary harmonic trends of the deviation curve,it is shown that gear profile form and slope deviations in different work generating sections of the involute cam are different which the latter changes with the cam eccentricity obviously.Then,the issues of extreme values and methods of error compensation are studied and the conclusion that large adjustable range is benefit to search the optimal involute-cam section which is responding to the minimum gear profile deviations is obtained.A group of examples are calculated by choosing master gears with d=120 mm and m=2-6 mm and an involute cam with base diameter djcam =117 mm.And it is found that the maximum gear profile deviation counts for no more than 5% of the cam eccentricity after error compensation.A gear-grinding experiment on the master gear with m=2 mm is conducted by choosing different sections of the involute cam and the differences of gear profile deviations then the existence of the cam eccentricity are verified.The research discloses the rule of gear profile deviations caused by the comprehensive eccentricity of the involute cam and provides the theoretical guidance and the processing methods for grinding profile of the ultra precision master gear.展开更多
To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device （VAFTCEPGD）, a prototype is designed and experiment is car...To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device （VAFTCEPGD）, a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.展开更多
For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution o...For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution obeys the Boltzmann statistics. It is shown that the temperature in the space charge distribution factor has an important effect on the energy band, barrier height and width of the space charge region. The depletion approximation is a model in which the temperature in the space charge distribution factor is zero. Our results are better than the depletion approximation.展开更多
With the development trend of the times, colleges and universities should vigorously carry out the construction of teaching management information and formulate strict and standardized information management rules and...With the development trend of the times, colleges and universities should vigorously carry out the construction of teaching management information and formulate strict and standardized information management rules and regulations to adapt to the long-term development of the school itself. At the same time, the majority of teachers and students should also assume the responsibility of information-based teaching management innovation, pay attention to the application of information technology, promote the development of information-based teaching management, in order to improve the quality of running a university. Teaching management has become an index to measure the level of running a school and plays an important role in the cultivation of talents in Colleges and universities. Whether the teaching management can be carried out efficiently is closely related to the scientificity of the management mode. Integrating information means into teaching management in Colleges and universities can optimize management means, reduce human cost and improve work efficiency.展开更多
文摘In order to improve nitrogen removal in anoxic/oxic(A/O) process effectively for treating domestic wastewaters, the influence factors, DO(dissolved oxygen), nitrate recirculation, sludge recycle, SRT(solids residence time), influent COD/TN and HRT(hydraulic retention time) were studied. Results indicated that it was possible to increase nitrogen removal by using corresponding control strategies, such as, adjusting the DO set point according to effluent ammonia concentration; manipulating nitrate recirculation flow according to nitrate concentration at the end of anoxic zone. Based on the experiments results, a knowledge-based approach for supervision of the nitrogen removal problems was considered, and decision trees for diagnosing nitrification and denitrification problems were built and successfully applied to A/O process.
基金supported by National Hi-tech Research and Development Program of China (863 Program,Grant No.2008AA042506)
文摘The manufacturing accuracy of ultra-precision master gears signifies the technological capability of the ultra-precision gear.Currently,there is little report about the manufacturing technologies of ultra-precision master gears at home and aboard.In order to meet the requirement of grinding ultra precision master gear,the gear grinder with flat-faced wheel Y7125 is chosen as the object machine tool and the geometric model of its precision generating part,the involute cam,is established.According to the structure of the involute cam,the effective working section and its adjustable range of the cam are determined,and the mathematical expressions of the effects of comprehensive eccentricity of the involute cam on gear profile deviations are derived.According to the primary harmonic trends of the deviation curve,it is shown that gear profile form and slope deviations in different work generating sections of the involute cam are different which the latter changes with the cam eccentricity obviously.Then,the issues of extreme values and methods of error compensation are studied and the conclusion that large adjustable range is benefit to search the optimal involute-cam section which is responding to the minimum gear profile deviations is obtained.A group of examples are calculated by choosing master gears with d=120 mm and m=2-6 mm and an involute cam with base diameter djcam =117 mm.And it is found that the maximum gear profile deviation counts for no more than 5% of the cam eccentricity after error compensation.A gear-grinding experiment on the master gear with m=2 mm is conducted by choosing different sections of the involute cam and the differences of gear profile deviations then the existence of the cam eccentricity are verified.The research discloses the rule of gear profile deviations caused by the comprehensive eccentricity of the involute cam and provides the theoretical guidance and the processing methods for grinding profile of the ultra precision master gear.
基金supported by the National Natural Science Foundation of China(Grant Nos.51309068,51309069,51579055 and 11572094)the Special Funded of Innovational Talents of Science and Technology in Harbin(Grant No.RC2014QN001008)+1 种基金the China Postdoctoral Science Foundation(Grant Nos.2014M561334 and 2015T80330)the Heilongjiang Postdoctoral Science Foundation(Grant No.LBH-Z14060)
文摘To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device （VAFTCEPGD）, a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.
文摘For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution obeys the Boltzmann statistics. It is shown that the temperature in the space charge distribution factor has an important effect on the energy band, barrier height and width of the space charge region. The depletion approximation is a model in which the temperature in the space charge distribution factor is zero. Our results are better than the depletion approximation.
文摘With the development trend of the times, colleges and universities should vigorously carry out the construction of teaching management information and formulate strict and standardized information management rules and regulations to adapt to the long-term development of the school itself. At the same time, the majority of teachers and students should also assume the responsibility of information-based teaching management innovation, pay attention to the application of information technology, promote the development of information-based teaching management, in order to improve the quality of running a university. Teaching management has become an index to measure the level of running a school and plays an important role in the cultivation of talents in Colleges and universities. Whether the teaching management can be carried out efficiently is closely related to the scientificity of the management mode. Integrating information means into teaching management in Colleges and universities can optimize management means, reduce human cost and improve work efficiency.
