Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrat...Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrator for the famous 4-20 mA electrical signaling scheme. The loop calibrator generates a linear current signal from 4 to 20 mA over a 250 ? typical process instrument load for calibration. The realization of the loop calibrator relies on a voltage-to-current converter to build a constant current source. The voltage controlled constant current source is built from discrete components and an op-amp to keep the cost low. Results from simulations and the prototype demonstrate the performance of the 4-20 mA loop calibrator which utilizes a greatly reduced number of components. The cost of these components is approximately 34% of the least expensive calibrator sampled, though other production costs are not included. This conclusion reinforces the fact that loop calibrators can be cheaper.展开更多
A jet inner-loop bioreactor (JIBR) was used to treat synthetic sanitary sewage with low, medium and high COD load. The experimental results show that it could meet discharge standard at 20\|30 min of HRT (hydraulic re...A jet inner-loop bioreactor (JIBR) was used to treat synthetic sanitary sewage with low, medium and high COD load. The experimental results show that it could meet discharge standard at 20\|30 min of HRT (hydraulic retention time) for low COD concentration and 60\|120 min of HRT for medium and high COD concentration. The maximal COD volume loading and COD sludge loading of 27 kg\5m -3 \5d -1 and 5 kg/d per kg MLSS were acheived respectively, that were 10\|20 times higher than those of traditional wastewater treatment processes. The BOD 5 removal efficiency was more than 90% and NH + 4 —N more than 85%. The study on the activity showed that the oxygen consumption rate of the activated sludge in the JIBR was 39.13 mg\5L -1 \5h -1 , which was 1.7 times higher than that of the SBR(Sequencing Batch Reactor) and the dominant bacteria in jet inner\|loop bioreactor was Pseudomonas species.展开更多
We describe the last glaciation climatic history Marine Isotope Stage(MIS, 2-4) from 66.7 ka to 14.5 ka in Hexigten, northeast Inner Mongolia, North China. The climate of the region experienced frequent and significan...We describe the last glaciation climatic history Marine Isotope Stage(MIS, 2-4) from 66.7 ka to 14.5 ka in Hexigten, northeast Inner Mongolia, North China. The climate of the region experienced frequent and significant fluctuations between dry-cold and less dry-cold during the late MIS4. The climate was generally warm and humid during early MIS3(MIS3 c) and late MIS3(MIS3 a), whereas it was cold and dry in middle MIS3(MIS3 b) and during MIS2. In this study, the cold and dry conditions were correlated with a stronger East Asian winter monsoon and strong dune activity; whereas, warm and humid conditions were related to a stronger East Asian summer monsoon(EASM) and weak dune activity. This study establishes six distinct dry and cold intervals during the last glacial period(66.7-14.5 ka) based on optically stimulated luminescence data, multi-proxies record(magnetic susceptibility, grain size analysis, Rb/Sr, SiO2/TiO2) and chemical index of alteration(CIA). The last glacial period may be correlated with Heinrich events 1 to 6 which were further confirmed by comparison with the Hulu cave stalagmites and Greenland ice core records. It is concluded that the study area was substantially affected by the EASM, as compared with the loess-desert transition zone of the Chinese Loess Plateau, especially in MIS3 c and suggested that the East Asian monsoon played a pivotal role in the last glacial period climate and dune activity.展开更多
文摘Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrator for the famous 4-20 mA electrical signaling scheme. The loop calibrator generates a linear current signal from 4 to 20 mA over a 250 ? typical process instrument load for calibration. The realization of the loop calibrator relies on a voltage-to-current converter to build a constant current source. The voltage controlled constant current source is built from discrete components and an op-amp to keep the cost low. Results from simulations and the prototype demonstrate the performance of the 4-20 mA loop calibrator which utilizes a greatly reduced number of components. The cost of these components is approximately 34% of the least expensive calibrator sampled, though other production costs are not included. This conclusion reinforces the fact that loop calibrators can be cheaper.
文摘A jet inner-loop bioreactor (JIBR) was used to treat synthetic sanitary sewage with low, medium and high COD load. The experimental results show that it could meet discharge standard at 20\|30 min of HRT (hydraulic retention time) for low COD concentration and 60\|120 min of HRT for medium and high COD concentration. The maximal COD volume loading and COD sludge loading of 27 kg\5m -3 \5d -1 and 5 kg/d per kg MLSS were acheived respectively, that were 10\|20 times higher than those of traditional wastewater treatment processes. The BOD 5 removal efficiency was more than 90% and NH + 4 —N more than 85%. The study on the activity showed that the oxygen consumption rate of the activated sludge in the JIBR was 39.13 mg\5L -1 \5h -1 , which was 1.7 times higher than that of the SBR(Sequencing Batch Reactor) and the dominant bacteria in jet inner\|loop bioreactor was Pseudomonas species.
基金supported by the Research Fund for Hexigten Global Geopark(Grant No.62932014004)Specialized Fund for Fundamental Research Program of China University of Geosciences,Beijing(Grant No.2011YYL016)+1 种基金the Specialized Fund for Public Welfare Industry,Ministry of Land and Resources of China(Grant No.201211077-3)the Specialized Research Fund for the Doctoral Program of Higher Education of China(for PhD supervisors,Grant No.20110022110005)
文摘We describe the last glaciation climatic history Marine Isotope Stage(MIS, 2-4) from 66.7 ka to 14.5 ka in Hexigten, northeast Inner Mongolia, North China. The climate of the region experienced frequent and significant fluctuations between dry-cold and less dry-cold during the late MIS4. The climate was generally warm and humid during early MIS3(MIS3 c) and late MIS3(MIS3 a), whereas it was cold and dry in middle MIS3(MIS3 b) and during MIS2. In this study, the cold and dry conditions were correlated with a stronger East Asian winter monsoon and strong dune activity; whereas, warm and humid conditions were related to a stronger East Asian summer monsoon(EASM) and weak dune activity. This study establishes six distinct dry and cold intervals during the last glacial period(66.7-14.5 ka) based on optically stimulated luminescence data, multi-proxies record(magnetic susceptibility, grain size analysis, Rb/Sr, SiO2/TiO2) and chemical index of alteration(CIA). The last glacial period may be correlated with Heinrich events 1 to 6 which were further confirmed by comparison with the Hulu cave stalagmites and Greenland ice core records. It is concluded that the study area was substantially affected by the EASM, as compared with the loess-desert transition zone of the Chinese Loess Plateau, especially in MIS3 c and suggested that the East Asian monsoon played a pivotal role in the last glacial period climate and dune activity.
