The pore structural characteristics have been the key to the studies on the mechanisms of fluids flow in porous media. With the development of experimental technology, the modern high-resolution equipments are capable...The pore structural characteristics have been the key to the studies on the mechanisms of fluids flow in porous media. With the development of experimental technology, the modern high-resolution equipments are capable of capturing pore structure images with a resolution of microns. But so far only 3D volume data of millimeter-scale rock samples can be obtained losslessly. It is necessary to explore the way of virtually reconstructing larger volume digital samples of porous media with the representative structural characteristics of the pore space. This paper proposes a reconstruction method of porous media using the structural characteristics captured by the data templates of multiple-point geostatistics. In this method, the probability of each structural characteristic of a pore space is acquired first, and then these characteristics are reproduced according to the probabilities to present the real structural characteristics in the reconstructed images. Our experimental results have shown that: (i) the deviation of LBM computed permeability respectively on the virtually reconstructed sandstone and the original sample is less than 1.2%; (ii) the reconstructed sandstone and the original sample have similar structural characteristics demonstrated by the variogram curves.展开更多
Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring ...Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring and remote operation,offering users high level of safety,convenience and comfort.Moreover,noncontact sensing is ideal to maximize the immersive user experience in the human–machine interaction(HMI),eliminating interference to human activities and mechanical fatigue to the sensor,simultaneously.Herein,we report a self-powered flexible sensor integrated with irradiation cross-linked polypropylene(IXPP)piezoelectret film for noncontact sensing,featuring multi-functions to detect mechanical signals transmitted through solid,liquid and gaseous media and would facilitate their versatile practical applications.The folded-structure configuration of the sensor facilitates the improvement of the noncontact sensing sensitivity.For solid media,such as the rectangular wooden stick used in this study,the sensor can detect mechanical stimulus exerted at a distance of 100 cm.A system detection sensitivity up to 57 pC/kPa with a low detection limit of 0.6 kPa is achieved at a noncontact distance of 10 cm.Even when partly or completely immersed in water,the sensor effectively traces movement signals of human bodies underwater,demonstrating great advantages for non-inductive aquatic fitness training monitoring.Furthermore,due to the low acoustic impedance of piezoelectret film,speech recognition through gaseous medium is also achieved.We further introduce application demonstrations of the developed film sensors to monitor exercise postures and physiological signals without direct contact between human body and the sensor,displaying great potential to be incorporated into future smart electronics.This study commendably expands the application scope of piezoelectret materials,which will have profound implications for exploring novel intelligent human–machine interactions.展开更多
基金supported by the Major Program of the Chinese Academy of Sciences (Grant No. KJCX1-YW-21)the National Natural Science Foundation of China (Grant Nos. 10672159, 10702069 and 10932010)the National Basic Research Program of China (Grant No.2006CB705805)
文摘The pore structural characteristics have been the key to the studies on the mechanisms of fluids flow in porous media. With the development of experimental technology, the modern high-resolution equipments are capable of capturing pore structure images with a resolution of microns. But so far only 3D volume data of millimeter-scale rock samples can be obtained losslessly. It is necessary to explore the way of virtually reconstructing larger volume digital samples of porous media with the representative structural characteristics of the pore space. This paper proposes a reconstruction method of porous media using the structural characteristics captured by the data templates of multiple-point geostatistics. In this method, the probability of each structural characteristic of a pore space is acquired first, and then these characteristics are reproduced according to the probabilities to present the real structural characteristics in the reconstructed images. Our experimental results have shown that: (i) the deviation of LBM computed permeability respectively on the virtually reconstructed sandstone and the original sample is less than 1.2%; (ii) the reconstructed sandstone and the original sample have similar structural characteristics demonstrated by the variogram curves.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.62201392,12174061 and 12374451).
文摘Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring and remote operation,offering users high level of safety,convenience and comfort.Moreover,noncontact sensing is ideal to maximize the immersive user experience in the human–machine interaction(HMI),eliminating interference to human activities and mechanical fatigue to the sensor,simultaneously.Herein,we report a self-powered flexible sensor integrated with irradiation cross-linked polypropylene(IXPP)piezoelectret film for noncontact sensing,featuring multi-functions to detect mechanical signals transmitted through solid,liquid and gaseous media and would facilitate their versatile practical applications.The folded-structure configuration of the sensor facilitates the improvement of the noncontact sensing sensitivity.For solid media,such as the rectangular wooden stick used in this study,the sensor can detect mechanical stimulus exerted at a distance of 100 cm.A system detection sensitivity up to 57 pC/kPa with a low detection limit of 0.6 kPa is achieved at a noncontact distance of 10 cm.Even when partly or completely immersed in water,the sensor effectively traces movement signals of human bodies underwater,demonstrating great advantages for non-inductive aquatic fitness training monitoring.Furthermore,due to the low acoustic impedance of piezoelectret film,speech recognition through gaseous medium is also achieved.We further introduce application demonstrations of the developed film sensors to monitor exercise postures and physiological signals without direct contact between human body and the sensor,displaying great potential to be incorporated into future smart electronics.This study commendably expands the application scope of piezoelectret materials,which will have profound implications for exploring novel intelligent human–machine interactions.
