Understanding the complex flow behavior along a rough rock fracture under high-temperature,high-stress,and high-seepage pressure(HTHM)coupling conditions is of great significance for optimizing deep resource extractio...Understanding the complex flow behavior along a rough rock fracture under high-temperature,high-stress,and high-seepage pressure(HTHM)coupling conditions is of great significance for optimizing deep resource extraction.This study investigates the complex flow behavior of a single rock fracture under coupled HTHM conditions using a self-developed multi-field coupling experimental system,considering real-time high temperatures(20–90℃),confining pressures(30–120 MPa),and seepage pressures(5–60 MPa).Experimental results show that as confining pressure increases,two typical nonlinear flow behaviors are observed,which are Forchheimer flow and low-velocity nonlinear flow.The increase in temperature and decrease in roughness significantly promote the fluid flow and enhance the nonlinear relationship between the volumetric flow rate and the hydraulic gradient at lower confining pressures(30 MPa).However,the change in temperature and fracture surface roughness does not affect the nonlinear type of fluid flow.Under a given hydraulic gradient,the influence of temperature and fracture roughness on the volumetric flow rate varies with changes in confining pressure.Additionally,this study considers both the viscous and inertial terms,and a modified Forchheimer equation is proposed using two parameters:the contact area ratio and the thermal expansion coefficient of the rock.The proposed model can effectively predict the nonlinear flow behavior of fluid along rough fractured rocks under varying temperatures and surface roughness.The experimental results and the proposed model provide valuable data and theoretical guidance for deep oil and gas exploration as well as hydraulic fracturing design.展开更多
Carbonaceous mudstone is a potential embankment filler in mountainous regions with limited high-quality materials;however,its engineering performance in highway embankments under complex environmental conditions remai...Carbonaceous mudstone is a potential embankment filler in mountainous regions with limited high-quality materials;however,its engineering performance in highway embankments under complex environmental conditions remains poorly understood.This study aimed to investigate the mechanical properties and failure mechanisms of carbonaceous mudstone filler under different temperature-moisture coupled conditions.Triaxial shear tests were conducted under four temperaturemoisture coupled conditions:dry-heat to dry-cold(DHDC),wet-cold to wet-heat(WCWH),dry-cold to wet-heat(DCWH),and dry-heat to wet-cold(DHWC).The effects of these conditions on the strength characteristics,relative breakage ratio,failure mode,and microscopic morphology were examined.A segmented prediction model based on the DuncanChang model was applied to validate the experimental results under the DHWC condition.The failure mechanisms under different conditions were also analyzed.The results indicate that the degradation of carbonaceous mudstone increases in the following order:DHDC,WCWH,DCWH,and DHWC.Under the DHDC condition,the stress-strain curves exhibit strain-softening behavior,while other conditions show strain-hardening behavior,with peak deviatoric stress occurring at 2%and 4%axial strains,respectively.The shear strength decreases by up to 40%under the DHWC condition but remains nearly unchanged under the DHDC condition,showing a positive correlation with particle breakage.As the number of cycles increases,the failure surfaces gradually move downward.Higher confining pressure shifts failure mode from shear failure to shear slip or localized compression,and eventually to overall compression or expansion failure.The modified Duncan-Chang model accurately predicts the experimental results.These findings provide important guidance for the application of carbonaceous mudstone filler in highway embankment construction in humid mountainous regions.展开更多
Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by esta...Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide–wind–wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5–6; while wind drag contributes mostly at wind scale 2–4.展开更多
A novel numerical scheme to solve two coupled systems of conservation laws is introduced.The scheme is derived based on a relaxation approach and does not require information on the Lax curves of the coupled systems,w...A novel numerical scheme to solve two coupled systems of conservation laws is introduced.The scheme is derived based on a relaxation approach and does not require information on the Lax curves of the coupled systems,which simplifies the computation of suitable coupling data.The coupling condition for the underlying relaxation system plays a crucial role as it determines the behaviour of the scheme in the zero relaxation limit.The role of this condition is discussed,a consistency concept with respect to the original problem is introduced,the well-posedness is analyzed and explicit,nodal Riemann solvers are provided.Based on a case study considering the p-system of gas dynamics,a strategy for the design of the relaxation coupling condition within the new scheme is provided.展开更多
Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition, we demonstrate the approximation of eliminating populations of atomic excited ...Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition, we demonstrate the approximation of eliminating populations of atomic excited states, which is widely used in the field of the atom cavity systems [Hechenblaikner G, Gangl M, Horak P and Ritsch H 1998 Phys. Rev. A 58 3030]; Liu L W, Tan T and Xu Y 2008 J. Mod. Opt. 56 968; Cho J, Angelakis D G and Bose S 2008 Phys. Rev. A 78 062338. This is reflected in the deviation of the population 5, of which the value is 10^-3 - 10^-2. We further find the deviation of the dipole force and demonstrate that the deviation of atomic population will not notably affect the dipole force of the atom in the strong coupling condition. A relevant experimental case is also presented.展开更多
This study describes a multidimensional 3D/lumped parameter（LP） model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the ...This study describes a multidimensional 3D/lumped parameter（LP） model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the entire arterial network（48 arteries） was developed including the effect of vessel diameter tapering and the parameterization of resistance, conductor and inductor variables. A computer aided-design（CAD） algorithm was proposed to effciently handle the coupling of two or more 3D models with the LP model, and substantially lessen the coupling processing time. Realistic boundary conditions and Navier-Stokes equations in healthy and stenosed models of carotid artery bifurcation（CAB） were used to investigate the unsteady Newtonian blood flow velocity distribution in the internal carotid artery（ICA）. The present simulation results agree well with previous experimental and numerical studies. The outcomes of a pure LP model and those of the coupled 3D healthy model were found to be nearly the same in both cases. Concerning the various analyzed 3D zones, the stenosis growth in the ICA was not found as a crucial factor in determining the absorbing boundary conditions.This paper demonstrates the advantages of coupling local and systemic models to comprehend physiological diseases of the cardiovascular system.展开更多
The recently proposed numerical algorithm,deep BSDE method,has shown remarkable performance in solving high-dimensional forward-backward stochastic differential equations(FBSDEs)and parabolic partial differential equa...The recently proposed numerical algorithm,deep BSDE method,has shown remarkable performance in solving high-dimensional forward-backward stochastic differential equations(FBSDEs)and parabolic partial differential equations(PDEs).This article lays a theoretical foundation for the deep BSDE method in the general case of coupled FBSDEs.In particular,a posteriori error estimation of the solution is provided and it is proved that the error converges to zero given the universal approximation capability of neural networks.Numerical results are presented to demonstrate the accuracy of the analyzed algorithm in solving high-dimensional coupled FBSDEs.展开更多
In this paper, PID（proportional-integral-derivative） controllers will be designed to solve the tracking problem for a class of coupled multi-agent systems, where each agent is described by a second-order high-dimens...In this paper, PID（proportional-integral-derivative） controllers will be designed to solve the tracking problem for a class of coupled multi-agent systems, where each agent is described by a second-order high-dimensional nonlinear uncertain dynamical system, which only has access to its own tracking error information and does not need to communicate with others. This paper will show that a 3-dimensional manifold can be constructed based on the information about the Lipschitz constants of the system nonlinear dynamics, such that whenever the three parameters of each PID controller are chosen from the manifold, the whole multi-agent system can be stabilized globally and the tracking error of each agent approaches to zero asymptotically. For a class of coupled first-order multi-agent nonlinear uncertain systems, a PI controller will be designed to stabilize the whole system.展开更多
Based on some recent results for interlacing eigenvalue intervals from 1-parameter families of se- quences of eigenvalue inequalities, a new method is given to solving the index problem for Sturm-Liouville eigenvalues...Based on some recent results for interlacing eigenvalue intervals from 1-parameter families of se- quences of eigenvalue inequalities, a new method is given to solving the index problem for Sturm-Liouville eigenvalues for coupled self-adjoint boundary conditions in the regular case. The key is a new characteristic principle for indices for Sturm-Liouville eigenvalues. The algorithm corresponding on the characteristic princi- ple are discussed, and numerical examples are presented to illustrate the theoretical results and show that the algorithm is valid.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52034010 and 52479113)the Natural Science Foundation of Shandong Province,China(No.ZR2024ME165)the Postgraduate Education and Teaching Reform Project of China University of Petroleum(East China)(No.YJG2024005).
文摘Understanding the complex flow behavior along a rough rock fracture under high-temperature,high-stress,and high-seepage pressure(HTHM)coupling conditions is of great significance for optimizing deep resource extraction.This study investigates the complex flow behavior of a single rock fracture under coupled HTHM conditions using a self-developed multi-field coupling experimental system,considering real-time high temperatures(20–90℃),confining pressures(30–120 MPa),and seepage pressures(5–60 MPa).Experimental results show that as confining pressure increases,two typical nonlinear flow behaviors are observed,which are Forchheimer flow and low-velocity nonlinear flow.The increase in temperature and decrease in roughness significantly promote the fluid flow and enhance the nonlinear relationship between the volumetric flow rate and the hydraulic gradient at lower confining pressures(30 MPa).However,the change in temperature and fracture surface roughness does not affect the nonlinear type of fluid flow.Under a given hydraulic gradient,the influence of temperature and fracture roughness on the volumetric flow rate varies with changes in confining pressure.Additionally,this study considers both the viscous and inertial terms,and a modified Forchheimer equation is proposed using two parameters:the contact area ratio and the thermal expansion coefficient of the rock.The proposed model can effectively predict the nonlinear flow behavior of fluid along rough fractured rocks under varying temperatures and surface roughness.The experimental results and the proposed model provide valuable data and theoretical guidance for deep oil and gas exploration as well as hydraulic fracturing design.
基金the financial support by the National Natural Science Foundation of China(52378440,42477143)the Key Science and Technology Program in the Transportation Industry(2022-MS1-032,2022-MS5-125)+2 种基金the Postgraduate Scientific Research Innovation Project of Hunan Province(CX20251302)the Science and Technology Innovation Program of Hunan Province(2024RC3166)the Guangxi Key Research and Development Program(AB23075184)。
文摘Carbonaceous mudstone is a potential embankment filler in mountainous regions with limited high-quality materials;however,its engineering performance in highway embankments under complex environmental conditions remains poorly understood.This study aimed to investigate the mechanical properties and failure mechanisms of carbonaceous mudstone filler under different temperature-moisture coupled conditions.Triaxial shear tests were conducted under four temperaturemoisture coupled conditions:dry-heat to dry-cold(DHDC),wet-cold to wet-heat(WCWH),dry-cold to wet-heat(DCWH),and dry-heat to wet-cold(DHWC).The effects of these conditions on the strength characteristics,relative breakage ratio,failure mode,and microscopic morphology were examined.A segmented prediction model based on the DuncanChang model was applied to validate the experimental results under the DHWC condition.The failure mechanisms under different conditions were also analyzed.The results indicate that the degradation of carbonaceous mudstone increases in the following order:DHDC,WCWH,DCWH,and DHWC.Under the DHDC condition,the stress-strain curves exhibit strain-softening behavior,while other conditions show strain-hardening behavior,with peak deviatoric stress occurring at 2%and 4%axial strains,respectively.The shear strength decreases by up to 40%under the DHWC condition but remains nearly unchanged under the DHDC condition,showing a positive correlation with particle breakage.As the number of cycles increases,the failure surfaces gradually move downward.Higher confining pressure shifts failure mode from shear failure to shear slip or localized compression,and eventually to overall compression or expansion failure.The modified Duncan-Chang model accurately predicts the experimental results.These findings provide important guidance for the application of carbonaceous mudstone filler in highway embankment construction in humid mountainous regions.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC0405401)the National Science&Technology Pillar Program(Grant No.2012BAB03B01)+1 种基金the Fundamental Research Funds for the Central Universities,Hohai University(Grant No.2014B30914)the Natural Science Foundation of Jiangsu Province(Grant No.BK2012411)
文摘Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide–wind–wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5–6; while wind drag contributes mostly at wind scale 2–4.
基金Funding Open Access funding enabled and organized by Projekt DEALthe Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)for the financial support through 320021702/GRK2326,333849990/IRTG-2379,B04,B05,and B06 of 442047500/SFB1481,HE5386/18-1,19-2,22-1,23-1,25-1,ERS SFDdM035 and under Germany’s Excellence Strategy EXC-2023 Internet of Production 390621612 and under the Excellence Strategy of the Federal Government and the Länder.Support through the EU DATAHYKING is also acknowledged.
文摘A novel numerical scheme to solve two coupled systems of conservation laws is introduced.The scheme is derived based on a relaxation approach and does not require information on the Lax curves of the coupled systems,which simplifies the computation of suitable coupling data.The coupling condition for the underlying relaxation system plays a crucial role as it determines the behaviour of the scheme in the zero relaxation limit.The role of this condition is discussed,a consistency concept with respect to the original problem is introduced,the well-posedness is analyzed and explicit,nodal Riemann solvers are provided.Based on a case study considering the p-system of gas dynamics,a strategy for the design of the relaxation coupling condition within the new scheme is provided.
基金supported by the National Natural Science Foundation of China (Grant No.10704031)the Fundamental Research Funds for the Central Universities,China (Grant No.lzujbky-2010-75)
文摘Using the master equation approach to a V-type three-level atom inside a high-finesse single-mode cavity in the strong coupling condition, we demonstrate the approximation of eliminating populations of atomic excited states, which is widely used in the field of the atom cavity systems [Hechenblaikner G, Gangl M, Horak P and Ritsch H 1998 Phys. Rev. A 58 3030]; Liu L W, Tan T and Xu Y 2008 J. Mod. Opt. 56 968; Cho J, Angelakis D G and Bose S 2008 Phys. Rev. A 78 062338. This is reflected in the deviation of the population 5, of which the value is 10^-3 - 10^-2. We further find the deviation of the dipole force and demonstrate that the deviation of atomic population will not notably affect the dipole force of the atom in the strong coupling condition. A relevant experimental case is also presented.
基金the Iranian National Science Foundation (INSF) for the financial support to this project (87040150)
文摘This study describes a multidimensional 3D/lumped parameter（LP） model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the entire arterial network（48 arteries） was developed including the effect of vessel diameter tapering and the parameterization of resistance, conductor and inductor variables. A computer aided-design（CAD） algorithm was proposed to effciently handle the coupling of two or more 3D models with the LP model, and substantially lessen the coupling processing time. Realistic boundary conditions and Navier-Stokes equations in healthy and stenosed models of carotid artery bifurcation（CAB） were used to investigate the unsteady Newtonian blood flow velocity distribution in the internal carotid artery（ICA）. The present simulation results agree well with previous experimental and numerical studies. The outcomes of a pure LP model and those of the coupled 3D healthy model were found to be nearly the same in both cases. Concerning the various analyzed 3D zones, the stenosis growth in the ICA was not found as a crucial factor in determining the absorbing boundary conditions.This paper demonstrates the advantages of coupling local and systemic models to comprehend physiological diseases of the cardiovascular system.
文摘The recently proposed numerical algorithm,deep BSDE method,has shown remarkable performance in solving high-dimensional forward-backward stochastic differential equations(FBSDEs)and parabolic partial differential equations(PDEs).This article lays a theoretical foundation for the deep BSDE method in the general case of coupled FBSDEs.In particular,a posteriori error estimation of the solution is provided and it is proved that the error converges to zero given the universal approximation capability of neural networks.Numerical results are presented to demonstrate the accuracy of the analyzed algorithm in solving high-dimensional coupled FBSDEs.
基金supported by the National Natural Science Foundation of China under Grant No.11688101
文摘In this paper, PID（proportional-integral-derivative） controllers will be designed to solve the tracking problem for a class of coupled multi-agent systems, where each agent is described by a second-order high-dimensional nonlinear uncertain dynamical system, which only has access to its own tracking error information and does not need to communicate with others. This paper will show that a 3-dimensional manifold can be constructed based on the information about the Lipschitz constants of the system nonlinear dynamics, such that whenever the three parameters of each PID controller are chosen from the manifold, the whole multi-agent system can be stabilized globally and the tracking error of each agent approaches to zero asymptotically. For a class of coupled first-order multi-agent nonlinear uncertain systems, a PI controller will be designed to stabilize the whole system.
基金Supported by the National Natural Science Foundation of China(No.11361039 and 11161030)the Natural Science Foundation of Inner Mongolia Province,China(No.2013MS0116)
文摘Based on some recent results for interlacing eigenvalue intervals from 1-parameter families of se- quences of eigenvalue inequalities, a new method is given to solving the index problem for Sturm-Liouville eigenvalues for coupled self-adjoint boundary conditions in the regular case. The key is a new characteristic principle for indices for Sturm-Liouville eigenvalues. The algorithm corresponding on the characteristic princi- ple are discussed, and numerical examples are presented to illustrate the theoretical results and show that the algorithm is valid.
