语料库用于外语教学和研究已被广泛探讨。但国内德语学习者普遍对德语语料库了解不多,难以主动且系统地使用语料库辅助德语学习。德语电子辞典(全称Das Digitale Wörterbuch der deutschen Sprache,网页:www.dwds.de)是权威且重要...语料库用于外语教学和研究已被广泛探讨。但国内德语学习者普遍对德语语料库了解不多,难以主动且系统地使用语料库辅助德语学习。德语电子辞典(全称Das Digitale Wörterbuch der deutschen Sprache,网页:www.dwds.de)是权威且重要的德语学习资源,该文详细介绍DWDS的结构和功能,并以实例探讨如何用其辅助不同阶段的德语词汇学习,以期为广大德语学习者提供示例。展开更多
Within the drinking water distribution system(DWDS)using chloramine as disinfectant,nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water qu...Within the drinking water distribution system(DWDS)using chloramine as disinfectant,nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water quality.To investigate efficient control strategies,operational conditions including hydraulic regimes and disinfectant scenarios were controlled within a flow cell experimental facility.Two test phases were conducted to investigate the effects on the extent of nitrification of three flow rates(Q=2,6,and 10 L/min)and four disinfection scenarios(total Cl2=1 mg/L,Cl2/NH3-N=3:1;total Cl2=1 mg/L,Cl2/NH3-N=5:1;total Cl2=5 mg/L,Cl2/NH3-N=3:1;and total Cl2=5 mg/L,Cl2/NH3-N=5:1).Physico-chemical parameters and nitrification indicators were monitored during the tests.The characteristics of biofilm extracellular polymetric substance(EPS)were evaluated after the experiment.The main results from the study indicate that nitrification is affected by hydraulic conditions and the process tends to be severe when the fluid flow transforms from laminar to turbulent(2300<Re<4000).Increasing disinfectant concentration and optimizing Cl2/NH3-N mass ratio were found to inhibit nitrification to some extend when the system was running at turbulent condition(Q=10 L/min,Re=5535).EPS extracted from biofilm that was established at the flow rate of 6 L/min had greater carbohydrate/protein ratio.Furthermore,several nitrification indicators were evaluated for their prediction efficiency and the results suggest that the change of nitrite,together with total organic carbon(TOC)and turbidity can indicate nitrification potential efficiently.展开更多
文摘语料库用于外语教学和研究已被广泛探讨。但国内德语学习者普遍对德语语料库了解不多,难以主动且系统地使用语料库辅助德语学习。德语电子辞典(全称Das Digitale Wörterbuch der deutschen Sprache,网页:www.dwds.de)是权威且重要的德语学习资源,该文详细介绍DWDS的结构和功能,并以实例探讨如何用其辅助不同阶段的德语词汇学习,以期为广大德语学习者提供示例。
基金support from the technicians at the School of Engineering,Cardiff University。
文摘Within the drinking water distribution system(DWDS)using chloramine as disinfectant,nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water quality.To investigate efficient control strategies,operational conditions including hydraulic regimes and disinfectant scenarios were controlled within a flow cell experimental facility.Two test phases were conducted to investigate the effects on the extent of nitrification of three flow rates(Q=2,6,and 10 L/min)and four disinfection scenarios(total Cl2=1 mg/L,Cl2/NH3-N=3:1;total Cl2=1 mg/L,Cl2/NH3-N=5:1;total Cl2=5 mg/L,Cl2/NH3-N=3:1;and total Cl2=5 mg/L,Cl2/NH3-N=5:1).Physico-chemical parameters and nitrification indicators were monitored during the tests.The characteristics of biofilm extracellular polymetric substance(EPS)were evaluated after the experiment.The main results from the study indicate that nitrification is affected by hydraulic conditions and the process tends to be severe when the fluid flow transforms from laminar to turbulent(2300<Re<4000).Increasing disinfectant concentration and optimizing Cl2/NH3-N mass ratio were found to inhibit nitrification to some extend when the system was running at turbulent condition(Q=10 L/min,Re=5535).EPS extracted from biofilm that was established at the flow rate of 6 L/min had greater carbohydrate/protein ratio.Furthermore,several nitrification indicators were evaluated for their prediction efficiency and the results suggest that the change of nitrite,together with total organic carbon(TOC)and turbidity can indicate nitrification potential efficiently.
