The failure of rocks is a complicated process as the mechanical properties of the rock are governed by loading history and cumulative ruptures.The geometric aspects of fractures,such as the size and shape of the fract...The failure of rocks is a complicated process as the mechanical properties of the rock are governed by loading history and cumulative ruptures.The geometric aspects of fractures,such as the size and shape of the fractures,the spatial distribution of the fracture networks,and the relations among these aspects also depend on the loads acting on rock mass.In general,the fractures are randomly generated in space which is difficult to be described using mathematical methods.In this paper,the failure processes of rock have been analyzed using the percolation theory.The results indicate that the failure process of rock is a transition from a stable state to an unstable state.This phenomenon is essentially consistent with the phase transition in the percolation theory.Based on this consistency,a theoretical model of percolation for earthquake prediction is proposed.A large number of seismic data provided strong evidence in support of the reliability and applicability of this model.展开更多
According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore ...According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the 'chamber-throat' model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.展开更多
High-k metal gate stacks are being used to suppress the gate leakage due to tunneling for sub-45 nm technology nodes.The reliability of thin dielectric films becomes a limitation to device manufacturing,especially to ...High-k metal gate stacks are being used to suppress the gate leakage due to tunneling for sub-45 nm technology nodes.The reliability of thin dielectric films becomes a limitation to device manufacturing,especially to the breakdown characteristic.In this work,a breakdown simulator based on a percolation model and the kinetic Monte Carlo method is set up,and the intrinsic relation between time to breakdown and trap generation rate R is studied by TDDB simulation.It is found that all degradation factors,such as trap generation rate time exponent m,Weibull slope β and percolation factor s,each could be expressed as a function of trap density time exponent α.Based on the percolation relation and power law lifetime projection,a temperature related trap generation model is proposed.The validity of this model is confirmed by comparing with experiment results.For other device and material conditions,the percolation relation provides a new way to study the relationship between trap generation and lifetime projection.展开更多
The crystal structures and electronic transport properties of composites, xLa5/8Ca3/8MnO3 （1-x）ErMnO3 （x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1）, where ErMnO3 is the insulating ferroelectric and La5/8Ca3/8MnO3 is the metal...The crystal structures and electronic transport properties of composites, xLa5/8Ca3/8MnO3 （1-x）ErMnO3 （x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1）, where ErMnO3 is the insulating ferroelectric and La5/8Ca3/8MnO3 is the metallic ferromagnetic component, were studied. The magnetization of samples （x=0, 0.5, 1） were also measured as a function of temperature from 4 K to 300 K. The X-ray diffraction data show La5/8Ca3/8MnO3 and ErMnO3 are almost complete immiscible, originating from the significant difference in their crystal structures. All the composites show a metal-insulator transition when the molar fraction of xLa5/8Ca3/8MnO3 component x≥0.4 and the electronic transport behaviors follow the classical percolation theory model very well. Magnetization of the mixture with x=0.5 is unique and enhanced greatly compared with that of pure ErMnO3. Comprehensive analysis of the electronic transport and magnetic results suggests that this material system is a new kind of multiferroic with stronger magnetism in a wider temperature range compared with the single phase multiferroic ErMnO3.展开更多
We present a workflow for upscaling of rock properties using microtomography and percolation theory. In this paper we focus on a pilot study for assessing the plastic strength of rocks from a digital rock image. First...We present a workflow for upscaling of rock properties using microtomography and percolation theory. In this paper we focus on a pilot study for assessing the plastic strength of rocks from a digital rock image. Firstly, we determine the size of mechanical representative volume ele- ment （RVE） by using upper/lower bound dissipation computations in accordance with thermody- namics. Then the mechanical RVE is used to simulate the rock failure at micro-scale using FEM. Two cases of different pressures of linear Drucker-Prager plasticity of rocks are computed to compute the macroscopic cohesion and the angle of internal friction of the rock. We also detect the critical exponents of yield stress for sealing laws from a series of derivative models that are created by a shrinking/expanding algorithm. We use microtomographic data sets of two carbonate samples and compare the results with previous results. The results show that natural rock samples with irregular structures may have the critical exponent of yield stress different from random models. This unexpected result could have significant ramifications for assessing the stability of solid materials with internal structure. Therefore our pilot study needs to be extended to investigate the scaling laws of strength of many more natural rocks with irregular microstructure.展开更多
Smoke is unexpected powder-splashing caused by electrostatic force and is one of the main problems hindering the process stability and applicability of the powder bed fusion electron beam(PBF-EB)tech-nology.In this st...Smoke is unexpected powder-splashing caused by electrostatic force and is one of the main problems hindering the process stability and applicability of the powder bed fusion electron beam(PBF-EB)tech-nology.In this study,mechanical stimulation was suggested to suppress smoke of gas-atomized(GA)Ti-48Al-2Cr-2Nb powder using Al_(2)O_(3) and WC ball milling.The deformation mechanism of the GA powder depending on the ball milling media was discussed based on the developed particle morphology distribu-tion map and contact mechanics simulation.It was revealed that the rapid decrement of flowability and packing density after WC ball milling owing to the formation of angular fragments by the brittle fracture.The variation of surface and electrical properties by mechanical stimulation was investigated via XPS,TEM,and Impedance analysis.The electrical resistivity of the ball-milled powders gradually decreased with increasing milling duration,despite the increased oxide film thickness,and the capacitive response disappeared in Al-60 and WC-30 via metal-insulator transition.This could be due to the accumulation of strain and defects on the oxide film via mechanical stimulation.The smoke mechanism of ball-milled powders was discussed based on the percolation theory.In the smoke experiment,smoke was more suppressed for WC-10 and WC-20 than that for Al-40 and Al-50,respectively,despite the longer charge dissipation time.This could be due to the high probability of contact with conductive particles.For the Al-60 and WC-30 powders,smoke was further restricted by the formation of a percolation cluster with metal-like electrical conductivity.We believe that this study will contribute to a better understanding of the smoke mechanism and process optimization of the PBF-EB.展开更多
The ionic transport process in polymer electrolytes (such as polyethylene oxide) wassimulated numerically on a two dimensional square lattice where charge carriers areaccommodated by the lattice sites connected random...The ionic transport process in polymer electrolytes (such as polyethylene oxide) wassimulated numerically on a two dimensional square lattice where charge carriers areaccommodated by the lattice sites connected randomly with available bonds to represent theamorphous chain configuration. Following the dynamic bond percolation theory(DBPT),the chainmotion contribution to the ionic conduction was incorporated via periodical renewal of the randombond configuration. To check and extend the prediction made by DBPT employing global abruptbond renewal,spatial correlation of the bond reassignment was introduced to the system by: 1)regional bond renewal and 2) organized bond motion. It is found that the difference between thediffusivities simulated involving regional bond renewal and those of DBPT becomes negligiblewhen the bond renewal rate approaches the carrier hopping rate.展开更多
The localised leakage in shield tunnels that mainly occurs at segment joints may induce other defects,which threatens operational safety.To obtain a universal solution for the sealant performance of gasketed joints,we...The localised leakage in shield tunnels that mainly occurs at segment joints may induce other defects,which threatens operational safety.To obtain a universal solution for the sealant performance of gasketed joints,we proposed a novel analytical model based on the multiscale contact and percolation theories,in which the obtained percolation pressure and interfacial separation can be utilized to derive the critical water leakage pressure and leakage rate.The evolutionary process of leakage was divided into three stages(i.e.,the percolation,leakage and breakdown),which explicitly reveal the progressive hydraulic deterioration of gasketed joints.The gaskets still own partial waterproof capacity until the end of the leakage stage due to the remaining contact pressure at surface asperities.The proposed model was first verified by several sets of experimental data,based on which the determination of three key model parameters(i.e.,self-sealing slope,sealing coefficient,and expel pressure)were discussed in detail.The parametric study indicates that the waterproof capacity is significantly affected by the joint opening,offset,and the surface roughness of the gaskets.The variation in waterproof capacity with joint opening is mainly due to the nonlinearity of the gasket’s modulus and self-sealing slope.The increase in joint offset can result in a lower waterproof capacity as well as a larger leakage rate.Gasket’s surface roughness affects the percolation pressure and interfacial separation,which contributes to the long-term sealant performance.展开更多
In recent years, there has been considerable attention and research on the higher-order interactions that are prevalent in various real-world networks. Hypergraphs, especially in the study of complex systems, are prov...In recent years, there has been considerable attention and research on the higher-order interactions that are prevalent in various real-world networks. Hypergraphs, especially in the study of complex systems, are proved effective in capturing these interactions. To better characterize the model in reality, this paper proposes a theoretical model of node interdependent percolation in multiplex hypergraphs, considering “weak” interdependence. The proposed model includes pairwise and higher-order interactions, where the removal of nodes triggers cascading failures. However, interdependent nodes connected to failed nodes experience partial loss of connections due to “weak” interdependence, reflecting the self-sustaining capabilities of real-world systems. Percolation theory is applied to the analysis to investigate the properties of the percolation threshold and phase transition. Both analysis and simulation results show that as the strength of interdependence between nodes weakens, the network transitions from a discontinuous to a continuous phase, thereby increasing its robustness.展开更多
Intruder detection and border surveillance are amongst the most promising applications of wireless sensor networks. Barrier coverage formulates these problems as constructing barriers in a long-thin region to detect i...Intruder detection and border surveillance are amongst the most promising applications of wireless sensor networks. Barrier coverage formulates these problems as constructing barriers in a long-thin region to detect intruders that cross the region. Existing studies on this topic are not only based on simplistic binary sensing model but also neglect the collaboration employed in many systems. In this paper, we propose a solution which exploits the collaboration of sensors to improve the performance of barrier coverage under probabilistic sensing model. First, the network width requirement, the sensor density and the number of barriers are derived under data fusion model when sensors are randomly distributed. Then, we present an efficient algorithm to construct barriers with a small number of sensors. The theoretical comparison shows that our solution can greatly improve barrier coverage via collaboration of sensors. We also conduct extensive simulations to demonstrate the effectiveness of our solution.展开更多
Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge.Structural models proposed for bulk metallic glasses are still controversial owing to experimen...Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge.Structural models proposed for bulk metallic glasses are still controversial owing to experimental difficulties in directly imaging the atom positions in three-dimensional structures.With the advanced atomic-resolution imaging,here we directly observed the atomic arrangements in atomically thin metallic glassy membranes obtained by vapor deposition.The atomic packing in the amorphous membrane is shown to have a fractal characteristic,with the fractal dimension depending on the atomic density.Locally,the atomic configuration for the metallic glass membrane is composed of many types of polygons with the bonding angles concentrated on 45°-55°.The fractal atomic structure is consistent with the analysis by the percolation theory,and may account for the enhanced relaxation dynamics and the easiness of glass transition as reported for the thin metallic glassy films or glassy surface.展开更多
Using the extensively studied V_(2)O_(3) as a prototype system, we investigate the role of percolation in metal-insulator transition(MIT). We apply scanning microwave impedance microscopy to directly determine the met...Using the extensively studied V_(2)O_(3) as a prototype system, we investigate the role of percolation in metal-insulator transition(MIT). We apply scanning microwave impedance microscopy to directly determine the metallic phase fraction p and relate it to the macroscopic conductance G, which shows a sudden jump when p reaches the percolation threshold. Interestingly, the conductance G exhibits a hysteretic behavior against p, suggesting two different percolating processes upon cooling and warming. Based on our image analysis and model simulation, we ascribe such hysteretic behavior to different domain nucleation and growth processes between cooling and warming, which is likely caused by the decoupled structural and electronic transitions in V_(2)O_(3) during MIT. Our work provides a microscopic view of how the interplay of structural and electronic degrees of freedom affects MIT in strongly correlated systems.展开更多
In the report the basic principles of new approach to the study of transport processes in porous medium are represented. The ＂percolation＂ approach has arisen as an attempt to overcome the traditional phenomenologic...In the report the basic principles of new approach to the study of transport processes in porous medium are represented. The ＂percolation＂ approach has arisen as an attempt to overcome the traditional phenomenological approach in the underground hydromechanics, based on the assumption of continuity of saturated porous media, which does not allow to explain and to model a number of effects arising from the fluids flow in porous media. The results obtained are very interesting not only from the scientific point of view but as the scientific basis for a number of enhanced oil recovery technologies.展开更多
基金financial support was provided by National Natural Science Foundation of China(Grant No.52122405)provided by Shanxi major research program for science and technology(Grant No.202101060301024).
文摘The failure of rocks is a complicated process as the mechanical properties of the rock are governed by loading history and cumulative ruptures.The geometric aspects of fractures,such as the size and shape of the fractures,the spatial distribution of the fracture networks,and the relations among these aspects also depend on the loads acting on rock mass.In general,the fractures are randomly generated in space which is difficult to be described using mathematical methods.In this paper,the failure processes of rock have been analyzed using the percolation theory.The results indicate that the failure process of rock is a transition from a stable state to an unstable state.This phenomenon is essentially consistent with the phase transition in the percolation theory.Based on this consistency,a theoretical model of percolation for earthquake prediction is proposed.A large number of seismic data provided strong evidence in support of the reliability and applicability of this model.
基金Supported by the National Natural Science Foundation of China(No.29776038).
文摘According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the 'chamber-throat' model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.
基金supported by the National High Technology Research and Development Program of China(Grant No.SS2015AA010601)the National Natural Science Foundation of China(Grant Nos.61176091 and 61306129)the Opening Project of Key Laboratory of Microelectronics Devices&Integrated Technology,Institute of Micro Electronics of Chinese Academy of Sciences
文摘High-k metal gate stacks are being used to suppress the gate leakage due to tunneling for sub-45 nm technology nodes.The reliability of thin dielectric films becomes a limitation to device manufacturing,especially to the breakdown characteristic.In this work,a breakdown simulator based on a percolation model and the kinetic Monte Carlo method is set up,and the intrinsic relation between time to breakdown and trap generation rate R is studied by TDDB simulation.It is found that all degradation factors,such as trap generation rate time exponent m,Weibull slope β and percolation factor s,each could be expressed as a function of trap density time exponent α.Based on the percolation relation and power law lifetime projection,a temperature related trap generation model is proposed.The validity of this model is confirmed by comparing with experiment results.For other device and material conditions,the percolation relation provides a new way to study the relationship between trap generation and lifetime projection.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.10774136）.
文摘The crystal structures and electronic transport properties of composites, xLa5/8Ca3/8MnO3 （1-x）ErMnO3 （x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1）, where ErMnO3 is the insulating ferroelectric and La5/8Ca3/8MnO3 is the metallic ferromagnetic component, were studied. The magnetization of samples （x=0, 0.5, 1） were also measured as a function of temperature from 4 K to 300 K. The X-ray diffraction data show La5/8Ca3/8MnO3 and ErMnO3 are almost complete immiscible, originating from the significant difference in their crystal structures. All the composites show a metal-insulator transition when the molar fraction of xLa5/8Ca3/8MnO3 component x≥0.4 and the electronic transport behaviors follow the classical percolation theory model very well. Magnetization of the mixture with x=0.5 is unique and enhanced greatly compared with that of pure ErMnO3. Comprehensive analysis of the electronic transport and magnetic results suggests that this material system is a new kind of multiferroic with stronger magnetism in a wider temperature range compared with the single phase multiferroic ErMnO3.
基金Petrobras’ financial support of this research and the permission of this publication
文摘We present a workflow for upscaling of rock properties using microtomography and percolation theory. In this paper we focus on a pilot study for assessing the plastic strength of rocks from a digital rock image. Firstly, we determine the size of mechanical representative volume ele- ment （RVE） by using upper/lower bound dissipation computations in accordance with thermody- namics. Then the mechanical RVE is used to simulate the rock failure at micro-scale using FEM. Two cases of different pressures of linear Drucker-Prager plasticity of rocks are computed to compute the macroscopic cohesion and the angle of internal friction of the rock. We also detect the critical exponents of yield stress for sealing laws from a series of derivative models that are created by a shrinking/expanding algorithm. We use microtomographic data sets of two carbonate samples and compare the results with previous results. The results show that natural rock samples with irregular structures may have the critical exponent of yield stress different from random models. This unexpected result could have significant ramifications for assessing the stability of solid materials with internal structure. Therefore our pilot study needs to be extended to investigate the scaling laws of strength of many more natural rocks with irregular microstructure.
基金This work was partially supported by JSPS KAKENHI(grant numbers 18H03834 and 21k14432)This research was also supported by“Materials Integration for Revolutionary Design System of Structure Materials”of the Cross-Ministerial Strategic Innovation Promotion Program(SIP)of Japan Science and Technology(JST).This work was also based on the results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization(NEDO)(JPNP14014).This work was partly supported by the Technology Research Association for Future Additive Manufacturing(TRAFAM).This work is also based on the results obtained from a project(JPNP19007)commissioned by the New Energy and Industrial Technology Development Organization(NEDO).
文摘Smoke is unexpected powder-splashing caused by electrostatic force and is one of the main problems hindering the process stability and applicability of the powder bed fusion electron beam(PBF-EB)tech-nology.In this study,mechanical stimulation was suggested to suppress smoke of gas-atomized(GA)Ti-48Al-2Cr-2Nb powder using Al_(2)O_(3) and WC ball milling.The deformation mechanism of the GA powder depending on the ball milling media was discussed based on the developed particle morphology distribu-tion map and contact mechanics simulation.It was revealed that the rapid decrement of flowability and packing density after WC ball milling owing to the formation of angular fragments by the brittle fracture.The variation of surface and electrical properties by mechanical stimulation was investigated via XPS,TEM,and Impedance analysis.The electrical resistivity of the ball-milled powders gradually decreased with increasing milling duration,despite the increased oxide film thickness,and the capacitive response disappeared in Al-60 and WC-30 via metal-insulator transition.This could be due to the accumulation of strain and defects on the oxide film via mechanical stimulation.The smoke mechanism of ball-milled powders was discussed based on the percolation theory.In the smoke experiment,smoke was more suppressed for WC-10 and WC-20 than that for Al-40 and Al-50,respectively,despite the longer charge dissipation time.This could be due to the high probability of contact with conductive particles.For the Al-60 and WC-30 powders,smoke was further restricted by the formation of a percolation cluster with metal-like electrical conductivity.We believe that this study will contribute to a better understanding of the smoke mechanism and process optimization of the PBF-EB.
文摘The ionic transport process in polymer electrolytes (such as polyethylene oxide) wassimulated numerically on a two dimensional square lattice where charge carriers areaccommodated by the lattice sites connected randomly with available bonds to represent theamorphous chain configuration. Following the dynamic bond percolation theory(DBPT),the chainmotion contribution to the ionic conduction was incorporated via periodical renewal of the randombond configuration. To check and extend the prediction made by DBPT employing global abruptbond renewal,spatial correlation of the bond reassignment was introduced to the system by: 1)regional bond renewal and 2) organized bond motion. It is found that the difference between thediffusivities simulated involving regional bond renewal and those of DBPT becomes negligiblewhen the bond renewal rate approaches the carrier hopping rate.
基金financially supported by the National Natural Science Foundation of China(Grant No.52278407)the Fundamental Research Funds for the Central Universities(Grant No.22120210573).
文摘The localised leakage in shield tunnels that mainly occurs at segment joints may induce other defects,which threatens operational safety.To obtain a universal solution for the sealant performance of gasketed joints,we proposed a novel analytical model based on the multiscale contact and percolation theories,in which the obtained percolation pressure and interfacial separation can be utilized to derive the critical water leakage pressure and leakage rate.The evolutionary process of leakage was divided into three stages(i.e.,the percolation,leakage and breakdown),which explicitly reveal the progressive hydraulic deterioration of gasketed joints.The gaskets still own partial waterproof capacity until the end of the leakage stage due to the remaining contact pressure at surface asperities.The proposed model was first verified by several sets of experimental data,based on which the determination of three key model parameters(i.e.,self-sealing slope,sealing coefficient,and expel pressure)were discussed in detail.The parametric study indicates that the waterproof capacity is significantly affected by the joint opening,offset,and the surface roughness of the gaskets.The variation in waterproof capacity with joint opening is mainly due to the nonlinearity of the gasket’s modulus and self-sealing slope.The increase in joint offset can result in a lower waterproof capacity as well as a larger leakage rate.Gasket’s surface roughness affects the percolation pressure and interfacial separation,which contributes to the long-term sealant performance.
基金supported by the Major Science and Technology Program of Henan Province(221100210700-2)。
文摘In recent years, there has been considerable attention and research on the higher-order interactions that are prevalent in various real-world networks. Hypergraphs, especially in the study of complex systems, are proved effective in capturing these interactions. To better characterize the model in reality, this paper proposes a theoretical model of node interdependent percolation in multiplex hypergraphs, considering “weak” interdependence. The proposed model includes pairwise and higher-order interactions, where the removal of nodes triggers cascading failures. However, interdependent nodes connected to failed nodes experience partial loss of connections due to “weak” interdependence, reflecting the self-sustaining capabilities of real-world systems. Percolation theory is applied to the analysis to investigate the properties of the percolation threshold and phase transition. Both analysis and simulation results show that as the strength of interdependence between nodes weakens, the network transitions from a discontinuous to a continuous phase, thereby increasing its robustness.
基金supported by the National Basic Research Program of China (2011CB302803)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA060307000)+1 种基金the National Natural Science Foundation of China (61003293)the IoT Development Project of MIIT and MoF under title ‘Research & Development of IoT Application Middleware and Its Industrialization’
文摘Intruder detection and border surveillance are amongst the most promising applications of wireless sensor networks. Barrier coverage formulates these problems as constructing barriers in a long-thin region to detect intruders that cross the region. Existing studies on this topic are not only based on simplistic binary sensing model but also neglect the collaboration employed in many systems. In this paper, we propose a solution which exploits the collaboration of sensors to improve the performance of barrier coverage under probabilistic sensing model. First, the network width requirement, the sensor density and the number of barriers are derived under data fusion model when sensors are randomly distributed. Then, we present an efficient algorithm to construct barriers with a small number of sensors. The theoretical comparison shows that our solution can greatly improve barrier coverage via collaboration of sensors. We also conduct extensive simulations to demonstrate the effectiveness of our solution.
基金This work was supported by the National Natural Science Foundation of China(51672307,51801230,51822107,and 51671121)the National Key Research and Development Program of China(2018YFA0703603)+2 种基金the National Natural Science Foundation of Guangdong Province(2019B030302010)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB30000000)Beijing Natural Science Foundation(Z190010).
文摘Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge.Structural models proposed for bulk metallic glasses are still controversial owing to experimental difficulties in directly imaging the atom positions in three-dimensional structures.With the advanced atomic-resolution imaging,here we directly observed the atomic arrangements in atomically thin metallic glassy membranes obtained by vapor deposition.The atomic packing in the amorphous membrane is shown to have a fractal characteristic,with the fractal dimension depending on the atomic density.Locally,the atomic configuration for the metallic glass membrane is composed of many types of polygons with the bonding angles concentrated on 45°-55°.The fractal atomic structure is consistent with the analysis by the percolation theory,and may account for the enhanced relaxation dynamics and the easiness of glass transition as reported for the thin metallic glassy films or glassy surface.
基金Fudan University was supported by the National Natural Science Foundation of China (Grant Nos. 12074080, 11804052, 11827805,11725521, and 12035004)the National Postdoctoral Program for Innovative Talents (Grant No. BX20180079)+5 种基金the Shanghai Science and Technology Committee Rising-Star Program (Grant No. 19QA1401000)the Science and Technology Commission of Shanghai Municipality (Grant No.20JC1414700)the Major Project (Grant No. 2019SHZDZX01)the Ministry of Science and Technology of China (Grant Nos. 2017YFA03030002021YFA1400100)(synthesis, structural characterization and global transport of V2O3) at University of California San Diego was supported by the US Air Force Office of Scientific Research (Grant No.FA9550-20-1-0242)。
文摘Using the extensively studied V_(2)O_(3) as a prototype system, we investigate the role of percolation in metal-insulator transition(MIT). We apply scanning microwave impedance microscopy to directly determine the metallic phase fraction p and relate it to the macroscopic conductance G, which shows a sudden jump when p reaches the percolation threshold. Interestingly, the conductance G exhibits a hysteretic behavior against p, suggesting two different percolating processes upon cooling and warming. Based on our image analysis and model simulation, we ascribe such hysteretic behavior to different domain nucleation and growth processes between cooling and warming, which is likely caused by the decoupled structural and electronic transitions in V_(2)O_(3) during MIT. Our work provides a microscopic view of how the interplay of structural and electronic degrees of freedom affects MIT in strongly correlated systems.
文摘In the report the basic principles of new approach to the study of transport processes in porous medium are represented. The ＂percolation＂ approach has arisen as an attempt to overcome the traditional phenomenological approach in the underground hydromechanics, based on the assumption of continuity of saturated porous media, which does not allow to explain and to model a number of effects arising from the fluids flow in porous media. The results obtained are very interesting not only from the scientific point of view but as the scientific basis for a number of enhanced oil recovery technologies.
