A novel noninvasive approach, based on flow-induced vibration, to the online flow regime identification for wet gas flow in a horizontal pipeline is proposed. Research into the flow-induced vibration response for the ...A novel noninvasive approach, based on flow-induced vibration, to the online flow regime identification for wet gas flow in a horizontal pipeline is proposed. Research into the flow-induced vibration response for the wet gas flow was conducted under the conditions of pipe diameter 50 mm, pressure from 0.25 MPa to 0.35 MPa, Lockhart-Martinelli parameter from 0.02 to 0.6, and gas Froude Number from 0.5 to 2.7. The flow-induced vibration signals were measured by a transducer installed on outside wall of pipe, and then the normalized energy features from different frequency bands in the vibration signals were extracted through 4-scale wavelet package transform. A "binary tree" multi-class support vector machine(MCSVM) classifier, with the normalized feature vector as inputs, and Gaussian radial basis function as kernel function, was developed to identify the three typical flow regimes including stratified wavy flow, annular mist flow, and slug flow for wet gas flow. The results show that the method can identify effectively flow regimes and its identification accuracy is about 93.3%. Comparing with the other classifiers, the MCSVM classifier has higher accuracy, especially under the case of small samples. The noninvasive measurement approach has great application prospect in online flow regime identification.展开更多
It is important to obtain a considerable quantity of DNA from oligotrophic environments such as a drinking water distribution system(DWDS)to study microbial communities by molecular biotechnology,and DNA yield is alwa...It is important to obtain a considerable quantity of DNA from oligotrophic environments such as a drinking water distribution system(DWDS)to study microbial communities by molecular biotechnology,and DNA yield is always one of the biggest problems when performing metagenomic sequencing on drinking water samples.To obtain as many microbes as possible,ultrasound has been widely used in cell detachment,but studies on the optimal ultrasonic parameters for biofilm in DWDS have rarely been seen.The effects of three ultrasonic parameters,including power,duration,and the number of ultrasound treatments(USTs)on the selected monoculture bacteria(Pelomonas sp.)biofilm were studied first.Then the optimal values of each ultrasonic parameter were initially determined.Based on these values,three levels of each ultrasonic parameter were selected,and then an orthogonal experiment was conducted to further study drinking water biofilm,and finally the optimal ultrasonic parameters for the effective separation of biofilm cells in DWDS were determined.The results showed that the optimal ultrasonic power,duration,and the number of USTs are 13 W,1 min,and 15,respectively.A 20-min interval is needed between two USTs.The present optimal UST,which does not lose DNA quality,can increase the amount of extractable DNA by at least 4.78 times compared to samples without UST.This study provides a pretreatment methodology for extracting more and reliable DNA from biofilm in DWDS,and can better solve the problem of DNA collection in oligotrophic environments.展开更多
基金Supported by the National Natural Science Foundation of China （60672003）
文摘A novel noninvasive approach, based on flow-induced vibration, to the online flow regime identification for wet gas flow in a horizontal pipeline is proposed. Research into the flow-induced vibration response for the wet gas flow was conducted under the conditions of pipe diameter 50 mm, pressure from 0.25 MPa to 0.35 MPa, Lockhart-Martinelli parameter from 0.02 to 0.6, and gas Froude Number from 0.5 to 2.7. The flow-induced vibration signals were measured by a transducer installed on outside wall of pipe, and then the normalized energy features from different frequency bands in the vibration signals were extracted through 4-scale wavelet package transform. A "binary tree" multi-class support vector machine(MCSVM) classifier, with the normalized feature vector as inputs, and Gaussian radial basis function as kernel function, was developed to identify the three typical flow regimes including stratified wavy flow, annular mist flow, and slug flow for wet gas flow. The results show that the method can identify effectively flow regimes and its identification accuracy is about 93.3%. Comparing with the other classifiers, the MCSVM classifier has higher accuracy, especially under the case of small samples. The noninvasive measurement approach has great application prospect in online flow regime identification.
基金Project supported by the Major Science and Technology Program for Water Pollution Control and Treatment(No.2017ZX07201004)the National Natural Science Foundation of China(No.51678520)。
文摘It is important to obtain a considerable quantity of DNA from oligotrophic environments such as a drinking water distribution system(DWDS)to study microbial communities by molecular biotechnology,and DNA yield is always one of the biggest problems when performing metagenomic sequencing on drinking water samples.To obtain as many microbes as possible,ultrasound has been widely used in cell detachment,but studies on the optimal ultrasonic parameters for biofilm in DWDS have rarely been seen.The effects of three ultrasonic parameters,including power,duration,and the number of ultrasound treatments(USTs)on the selected monoculture bacteria(Pelomonas sp.)biofilm were studied first.Then the optimal values of each ultrasonic parameter were initially determined.Based on these values,three levels of each ultrasonic parameter were selected,and then an orthogonal experiment was conducted to further study drinking water biofilm,and finally the optimal ultrasonic parameters for the effective separation of biofilm cells in DWDS were determined.The results showed that the optimal ultrasonic power,duration,and the number of USTs are 13 W,1 min,and 15,respectively.A 20-min interval is needed between two USTs.The present optimal UST,which does not lose DNA quality,can increase the amount of extractable DNA by at least 4.78 times compared to samples without UST.This study provides a pretreatment methodology for extracting more and reliable DNA from biofilm in DWDS,and can better solve the problem of DNA collection in oligotrophic environments.
