Permeability is a key parameter to describe fluid transport properties of porous medium; however, the permeability measurement is extremely difficult for tight porous medium, e.g. fine-grained rock or dense soil. In t...Permeability is a key parameter to describe fluid transport properties of porous medium; however, the permeability measurement is extremely difficult for tight porous medium, e.g. fine-grained rock or dense soil. In this paper, three methods for gas permeability measurement, i.e. steady state method, pulse decay method(PDM) and pressure oscillation method(POM), are first reviewed and then their advantages and drawbacks are discussed. Both analytical and numerical solutions of gas permeability are presented for the tight porous medium. The results show that the analytical method is relatively simple but only valid under certain conditions, whilst the numerical method is more robust and generic, which can take into account several factors such as porosity, saturation, gas leakage, and unconventional boundary conditions. The influence of the effective porosity on the permeability determination is further analyzed using the proposed numerical method. In this study, new pressure data interpretation procedures for PDM and POM are proposed, and the obtained results can serve as a guidance to define a proper method for permeability measurement of the tight porous medium.展开更多
采用STM32F103RCT6结合MP3V5050GP压力传感器设计了一款便携式腕式电子血压测量系统。算法采用变幅度系数法,克服了单一幅度系数法的个体适应性差的缺点;分离信号采用数字带通滤波器获取血压信号,并提出了静压曲线采用峰谷均值点拟合的...采用STM32F103RCT6结合MP3V5050GP压力传感器设计了一款便携式腕式电子血压测量系统。算法采用变幅度系数法,克服了单一幅度系数法的个体适应性差的缺点;分离信号采用数字带通滤波器获取血压信号,并提出了静压曲线采用峰谷均值点拟合的方法,使得静压线更加接近于线性放气;最大峰值采用前后序列均值和高斯拟合曲线峰值共同确定,使平均压准确、稳定,从而使以振荡脉搏波幅值为基础的变幅度系数法的计算结果更准确。经验证,该方法与标准听诊法相比误差均值在5 mm Hg内,符合ANSI/AAMI/ISO标准。展开更多
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 41572290, 51479190 and 51879260)the Chinese Fundamental Research (973) Program (Grant No. 2015CB057906)Hubei Provincial Natural Science Foundation of China (Grant No. 2018CFA012)
文摘Permeability is a key parameter to describe fluid transport properties of porous medium; however, the permeability measurement is extremely difficult for tight porous medium, e.g. fine-grained rock or dense soil. In this paper, three methods for gas permeability measurement, i.e. steady state method, pulse decay method(PDM) and pressure oscillation method(POM), are first reviewed and then their advantages and drawbacks are discussed. Both analytical and numerical solutions of gas permeability are presented for the tight porous medium. The results show that the analytical method is relatively simple but only valid under certain conditions, whilst the numerical method is more robust and generic, which can take into account several factors such as porosity, saturation, gas leakage, and unconventional boundary conditions. The influence of the effective porosity on the permeability determination is further analyzed using the proposed numerical method. In this study, new pressure data interpretation procedures for PDM and POM are proposed, and the obtained results can serve as a guidance to define a proper method for permeability measurement of the tight porous medium.
文摘采用STM32F103RCT6结合MP3V5050GP压力传感器设计了一款便携式腕式电子血压测量系统。算法采用变幅度系数法,克服了单一幅度系数法的个体适应性差的缺点;分离信号采用数字带通滤波器获取血压信号,并提出了静压曲线采用峰谷均值点拟合的方法,使得静压线更加接近于线性放气;最大峰值采用前后序列均值和高斯拟合曲线峰值共同确定,使平均压准确、稳定,从而使以振荡脉搏波幅值为基础的变幅度系数法的计算结果更准确。经验证,该方法与标准听诊法相比误差均值在5 mm Hg内,符合ANSI/AAMI/ISO标准。
