The traditional ground direct current method is not suitable for leakage detection of underground diaphragm walls in foundation pits because of its low accuracy and poor anti-noise ability.Here,we propose a joint surf...The traditional ground direct current method is not suitable for leakage detection of underground diaphragm walls in foundation pits because of its low accuracy and poor anti-noise ability.Here,we propose a joint surface-borehole observation device for leakage electric fi eld detection to achieve rapid measurement of the electric fi eld distribution characteristics at ground level in the foundation pit,thus enabling rapid localization of leakage points.We first establish the mechanism and basic equation of the leakage electric field response by combining the electric field formed by electrokinetic effect(EK)and the stable electric fi eld formed by conduction current in a combined leakage channel.Then,the fi nite–infi nite element coupling method is used to solve the electric fi eld equation to simulate the responses of a three-dimensional foundation pit leakage model.Furthermore,we conduct numerical simulations of diff erent pit models to investigate the infl uencing factors of the detection device and response characteristics of the change in the properties of the leakage channel.The results demonstrate that the proposed joint surface-borehole observation device can effi ciently reveal anomalous potential caused by leakage,and the amplitude of the electric fi eld generated by EK can eff ectively strengthen the leakage electric fi eld signal at the leakage,thus improving detection accuracy and effi ciency.展开更多
We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boun...We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boundary condition, for instance, the zero electrostatic potential in the middle of the channel. Using the similarity transformation, we employ the homotopy analysis method （HAM） to get the analytical solution of the model. In our approach, the unknown pressure constant and the integral constant related to the electric potential are solved spontaneously by using the proper boundary conditions on the channel walls, which makes our model consistent with the commonly accepted models in the field of fluid mechanics. It is expected that our model can offer a general and proper way to study the flow phenomena in microchannels.展开更多
We designed a new downhole electrokinetic logging tool based on numericalsimulations and petrophysical experiments. Acoustic and electric receivers cannot be arrangedat the same depth, and the proposed composite elect...We designed a new downhole electrokinetic logging tool based on numericalsimulations and petrophysical experiments. Acoustic and electric receivers cannot be arrangedat the same depth, and the proposed composite electrokinetic logging tool offers a solutionto this problem. The sound field characteristics of the detectors were tested in a water tank inthe laboratory. Then, we calculated the sound pressure of the radiated acoustic field and thetransmitting voltage response of the transmitting transducers; in addition, we analyzed thedirectivity and application of the acoustic transmitting probe based on linear phased array.The results suggest that the sound pressure generated at 1500 mm spacing reaches up to 47.2k Pa and decreases with increasing acoustic source frequency. When the excitation signalsdelay time of adjacent acoustic transmitting subarrays increases, the radiation beam of themain lobe is deflected and its energy gradually increases, which presumably enhances theacoustoelectric conversion efficiency.展开更多
Chen＇s technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen （LAC） generalized reflection and transmis...Chen＇s technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen （LAC） generalized reflection and transmission coefficients method, is confirmed to be efficient in dealing with elastic waves in multi-layered media and accurate in any frequency range. In this article, we extend Chen＇s technique to the computation of coupled seismic and electromagnetic （EM） waves in layered porous media. Expanding the involved mechanical and electromagnetic fields by a set of scalar and vector wave-function basis, we obtain the fundamental equations which are subsequently solved by using a recently developed version of the LAC generalized reflection and transmission coefficients method. Our approach and corresponding program is validated by reciprocity tests. We also show a numerical example of a two-layer model with an explosion source. The P-to-EM conversion waves radiated from the interface may have potential application.展开更多
The occurrence and development of earthquakes can cause abnormal changes in the lithospheric magnetic field.High-precision geomagnetic observations on both sides of the Dingri M6.8 epicenter revealed a−120 nT differen...The occurrence and development of earthquakes can cause abnormal changes in the lithospheric magnetic field.High-precision geomagnetic observations on both sides of the Dingri M6.8 epicenter revealed a−120 nT difference in the lithospheric magnetic field between the west and east sides,reflecting the local difference characteristics of the properties of the crustal medium around the epicenter.From 2018 to 2020,the annual variation of the magnetic field changed from−2.2 nT to+3.9 nT,which may be the precursor anomaly of the Dingri M5.9 earthquake in 2020.Calculations show that in the coseismic magnetic field variation of the M6.8 earthquake,the piezomagnetic effect is small while the electrokinetic effect is large,so the precursor anomaly of the M5.9 earthquake may be related to the electrokinetic effect produced by underground fluid migration.展开更多
Streaming potential is mainly related to electrokinetic energy conversion,which has been considered to show promising potential for advanced technologies,especially sensing.The inherent property of streaming potential...Streaming potential is mainly related to electrokinetic energy conversion,which has been considered to show promising potential for advanced technologies,especially sensing.The inherent property of streaming potential is that the energy conversion process is always a continuous state.However,practical applications include many cases of discontinuous states,such as nonlinear sensing.Here,we report a discontinuous streaming potential electrokinetic energy conversion fluid system.Experiments and theoretical calculations reveal that this system exhibits a discontinuous electrokinetic effect and provides a gating liquid slip in micropores,offering the advantages of gating liquid charge coupling and interfacial drag reduction.Moreover,the system is demonstrated in a wearable fall-down alert application.We expect this liquid gating energy conversion system to open up a platform for the design and application of autonomous health monitoring devices,seismic sea wave warning systems,and beyond.展开更多
The integration of ionic power generation with solar-driven water evaporation presents a promising solution to the critical global problems of freshwater scarcity and clean energy deficiency.In this work,a scalable no...The integration of ionic power generation with solar-driven water evaporation presents a promising solution to the critical global problems of freshwater scarcity and clean energy deficiency.In this work,a scalable normal temperature chemical vapor deposition(CVD)method is applied for the first time to the fabrication of a cellulose@polypyrrole(CC@PPy)membrane with efficient ionic power generation performance.The excellent ionic power generation is intimately related to the water and thermal gradients across the membrane,which not only induces fast water evaporation but also synergistically promotes the transport of counterions in charged nanochannels,and the corresponding mechanism is attributed to the streaming potential resulting from the ionic electrokinetic effect and the ionic thermoelectric potential originating from the Soret effect.Under one sun illumination,the CC@PPy film can produce a sustained voltage output of~0.7 V and a water evaporation rate up to 1.67 kg m^(−2)h^(−1)when an adequate water supply is available.This study provides new methods for the scalable fabrication of ionic power generation membranes and a design strategy for high-performance solar power generators.展开更多
基金partially supported by the National Natural Science Foundation of China (Nos. 41864004 and 41674077)Jiangxi Provincial Academic Leaders (Youth) Training Program (No. 20204BCJL23058)Open Fund from Engineering Research Center for Seismic Disaster Prevention and Engineering Geological Disaster Detection of Jiangxi Province (SDGD202102)。
文摘The traditional ground direct current method is not suitable for leakage detection of underground diaphragm walls in foundation pits because of its low accuracy and poor anti-noise ability.Here,we propose a joint surface-borehole observation device for leakage electric fi eld detection to achieve rapid measurement of the electric fi eld distribution characteristics at ground level in the foundation pit,thus enabling rapid localization of leakage points.We first establish the mechanism and basic equation of the leakage electric field response by combining the electric field formed by electrokinetic effect(EK)and the stable electric fi eld formed by conduction current in a combined leakage channel.Then,the fi nite–infi nite element coupling method is used to solve the electric fi eld equation to simulate the responses of a three-dimensional foundation pit leakage model.Furthermore,we conduct numerical simulations of diff erent pit models to investigate the infl uencing factors of the detection device and response characteristics of the change in the properties of the leakage channel.The results demonstrate that the proposed joint surface-borehole observation device can effi ciently reveal anomalous potential caused by leakage,and the amplitude of the electric fi eld generated by EK can eff ectively strengthen the leakage electric fi eld signal at the leakage,thus improving detection accuracy and effi ciency.
基金supported in part by the Australian Research Council through a Discovery Early Career Researcher Award to Qiang SUN
文摘We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boundary condition, for instance, the zero electrostatic potential in the middle of the channel. Using the similarity transformation, we employ the homotopy analysis method （HAM） to get the analytical solution of the model. In our approach, the unknown pressure constant and the integral constant related to the electric potential are solved spontaneously by using the proper boundary conditions on the channel walls, which makes our model consistent with the commonly accepted models in the field of fluid mechanics. It is expected that our model can offer a general and proper way to study the flow phenomena in microchannels.
基金supported by the National Science Foundation of China(No.61102102,11134011,11204380 and 11374371)Major National Science and Technology Projects(No.2011ZX05020-009)+1 种基金Science and Technology Project of CNPC(No.2014A-3912 and 2011B-4001)Petro China Innovation Foundation(No.2014D-5006-0307)
文摘We designed a new downhole electrokinetic logging tool based on numericalsimulations and petrophysical experiments. Acoustic and electric receivers cannot be arrangedat the same depth, and the proposed composite electrokinetic logging tool offers a solutionto this problem. The sound field characteristics of the detectors were tested in a water tank inthe laboratory. Then, we calculated the sound pressure of the radiated acoustic field and thetransmitting voltage response of the transmitting transducers; in addition, we analyzed thedirectivity and application of the acoustic transmitting probe based on linear phased array.The results suggest that the sound pressure generated at 1500 mm spacing reaches up to 47.2k Pa and decreases with increasing acoustic source frequency. When the excitation signalsdelay time of adjacent acoustic transmitting subarrays increases, the radiation beam of themain lobe is deflected and its energy gradually increases, which presumably enhances theacoustoelectric conversion efficiency.
基金supported by the Natural R&D Special Fund for Public Welfare Industry(No.200808069)National Natural Science Foundation of China(Nos.40974038,40774028 and 40821062)
文摘Chen＇s technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen （LAC） generalized reflection and transmission coefficients method, is confirmed to be efficient in dealing with elastic waves in multi-layered media and accurate in any frequency range. In this article, we extend Chen＇s technique to the computation of coupled seismic and electromagnetic （EM） waves in layered porous media. Expanding the involved mechanical and electromagnetic fields by a set of scalar and vector wave-function basis, we obtain the fundamental equations which are subsequently solved by using a recently developed version of the LAC generalized reflection and transmission coefficients method. Our approach and corresponding program is validated by reciprocity tests. We also show a numerical example of a two-layer model with an explosion source. The P-to-EM conversion waves radiated from the interface may have potential application.
基金supported by Hebei Earthquake Science and Technology Spark Program Project(Grant No.DZ2024112200008).
文摘The occurrence and development of earthquakes can cause abnormal changes in the lithospheric magnetic field.High-precision geomagnetic observations on both sides of the Dingri M6.8 epicenter revealed a−120 nT difference in the lithospheric magnetic field between the west and east sides,reflecting the local difference characteristics of the properties of the crustal medium around the epicenter.From 2018 to 2020,the annual variation of the magnetic field changed from−2.2 nT to+3.9 nT,which may be the precursor anomaly of the Dingri M5.9 earthquake in 2020.Calculations show that in the coseismic magnetic field variation of the M6.8 earthquake,the piezomagnetic effect is small while the electrokinetic effect is large,so the precursor anomaly of the M5.9 earthquake may be related to the electrokinetic effect produced by underground fluid migration.
基金National Natural Science Foundation of China(52025132,21975209,21621091,12075191)National Key R&D Program of China(2018YFA0209500)+3 种基金National Science Foundation of Fujian Province(2022J02059)Fundamental Research Funds for the Central Universities in China(20720220085)111 Project(B17027,B16029)Science and Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(grant no.RD2022070601).
文摘Streaming potential is mainly related to electrokinetic energy conversion,which has been considered to show promising potential for advanced technologies,especially sensing.The inherent property of streaming potential is that the energy conversion process is always a continuous state.However,practical applications include many cases of discontinuous states,such as nonlinear sensing.Here,we report a discontinuous streaming potential electrokinetic energy conversion fluid system.Experiments and theoretical calculations reveal that this system exhibits a discontinuous electrokinetic effect and provides a gating liquid slip in micropores,offering the advantages of gating liquid charge coupling and interfacial drag reduction.Moreover,the system is demonstrated in a wearable fall-down alert application.We expect this liquid gating energy conversion system to open up a platform for the design and application of autonomous health monitoring devices,seismic sea wave warning systems,and beyond.
基金supported by the National Natural Science Foundation of China(Grant Nos.52162012,52262014,22308074,22368019)Key Research and Development Project of Hainan Province(Grant Nos.ZDYF2022SHFZ053)+1 种基金Science and Technology Innovation Talent Platform Fund for South China Sea New Star of Hainan Province(Grant No.NHXXRCXM202305)Open Research Project of State Key Laboratory of Marine Resource Utilization in South China Sea(Grant No.MRUKF2023020).
文摘The integration of ionic power generation with solar-driven water evaporation presents a promising solution to the critical global problems of freshwater scarcity and clean energy deficiency.In this work,a scalable normal temperature chemical vapor deposition(CVD)method is applied for the first time to the fabrication of a cellulose@polypyrrole(CC@PPy)membrane with efficient ionic power generation performance.The excellent ionic power generation is intimately related to the water and thermal gradients across the membrane,which not only induces fast water evaporation but also synergistically promotes the transport of counterions in charged nanochannels,and the corresponding mechanism is attributed to the streaming potential resulting from the ionic electrokinetic effect and the ionic thermoelectric potential originating from the Soret effect.Under one sun illumination,the CC@PPy film can produce a sustained voltage output of~0.7 V and a water evaporation rate up to 1.67 kg m^(−2)h^(−1)when an adequate water supply is available.This study provides new methods for the scalable fabrication of ionic power generation membranes and a design strategy for high-performance solar power generators.
