Deep rock engineering is affected by coupled thermo-hydro-mechanical(THM)-dynamic fields,necessitating the elucidation of the dynamic mechanical behavior and failure mechanisms.This study utilized a Multi-field Couple...Deep rock engineering is affected by coupled thermo-hydro-mechanical(THM)-dynamic fields,necessitating the elucidation of the dynamic mechanical behavior and failure mechanisms.This study utilized a Multi-field Coupled Controlled Split Hopkinson Pressure Bar(MCC-SHPB)system to elucidate the cross-scale dynamic responses of rocks and the boundaries of failure modes under THM coupling.Impact tests were conducted on green sandstone under coupled conditions of temperature(25℃-80℃),confining pressure(0-15 MPa),and seepage water pressure(0-15 MPa).Scanning electron microscopy(SEM)microstructural characterization and COMSOL Multiphysics numerical simulations were conducted,and a dynamic constitutive theoretical framework and failure-prediction methodology were established.We investigated the impact toughness index(I_(t)),dynamic modulus(E_(d)),dynamic triaxial compressive strength(TCS_(d)),fragmentation degree(W),and failure modes of green sandstone under thermo-confining pressure-seepage-impact loading conditions.The key findings reveal that the(I_(t))reflects different energy regulation mechanisms across different confining pressure regimes.Thermal-microcrack interactions dominate at low pressure,and energy absorption prevails at high pressure.A triphasic dynamic modulus model captures stiffness evolution under energy-driven conditions,revealing cross-scale crack nucleation-propagation and fragment reorganization.The TCSd inflection point signifies energy dissipation shifts,causing nonlinear skeleton bearing-capacity degradation.A critical criterion based on the W was established to distinguish between the two failure modes and predict the unstable failure initiation.Numerical simulations were used to elucidate the effects of inertia-dominated crack propagation and stress wave interference,validating the critical criterion and the predictive accuracy of the theoretical model during cross-scale failure.This study provides a theoretical foundation for assessing the dynamic stability of rock masses subjected to multi-field coupling during deep resource exploitation.展开更多
The Electro–Hydrostatic Actuator(EHA)is applied to drive the control surface in flightcontrol system of more electric aircraft.In EHA,the Oil-Immersed Motor Pump(OMP)serves asthe core as a power assembly.However,the ...The Electro–Hydrostatic Actuator(EHA)is applied to drive the control surface in flightcontrol system of more electric aircraft.In EHA,the Oil-Immersed Motor Pump(OMP)serves asthe core as a power assembly.However,the compact integration of the OMP presents challenges inefficiently dissipating internal heat,leading to a performance degradation of the EHA due to ele-vated temperatures.Therefore,accurately modeling and predicting the internal thermal dynamicsof the OMP hold considerable significance for monitoring the operational condition of the EHA.In view of this,a modeling method considering cumulative thermal coupling was hereby proposed.Based on the proposed method,the thermal models of the motor and the pump were established,taking into account heat accumulation and transfer.Taking the leakage oil as the heat couplingpoint between the motor and the pump,the dynamic thermal coupling model of the OMP wasdeveloped,with the thermal characteristics of the oil considered.Additionally,the comparativeexperiments were conducted to illustrate the efficiency of the proposed model.The experimentalresults demonstrate that the proposed dynamic thermal coupling model accurately captured thethermal behavior of OMP,outperforming the static thermal parameter model.Overall,thisadvancement is crucial for effectively monitoring the health of EHA and ensuring flight safety.展开更多
Laser powder bed fusion(LPBF)has revolutionized modern manufacturing by enabling high design freedom,rapid prototyping,and tailored mechanical properties.However,optimizing process parameters remains challenging due t...Laser powder bed fusion(LPBF)has revolutionized modern manufacturing by enabling high design freedom,rapid prototyping,and tailored mechanical properties.However,optimizing process parameters remains challenging due to the trial-and-error approaches required to capture subtle parameter-microstructure relationships.This study employed a multi-physics computational framework to investigate the melting and solidification dynamics of magnesium alloy.By integrating the discrete element method for powder bed generation,finite volume method with volume of fluid for melt pool behavior,and phase-field method for microstructural evolution,the critical physical phenomena,including powder melting,molten pool flow,and directional solidification were simulated.The effects of laser power and scanning speed on temperature distribution,melt pool geometry,and dendritic morphology were systematically analyzed.It was revealed that increasing laser power expanded melt pool dimensions and promoted columnar dendritic growth,while high scanning speeds reduced melt pool stability and refined dendritic structures.Furthermore,Marangoni convection and thermal gradients governed solute redistribution,with excessive energy input risking defects such as porosity and elemental evaporation.These insights establish quantitative correlations between process parameters,thermal history,and microstructural characteristics,providing a validated roadmap for LPBF-processed magnesium alloy with tailored performance.展开更多
Conventional concentrator photovoltaics(CPV)face a persistent trade-off between high efficiency and high cost,driven by expensive multi-junction solar cells and complex active cooling systems.This study presents a com...Conventional concentrator photovoltaics(CPV)face a persistent trade-off between high efficiency and high cost,driven by expensive multi-junction solar cells and complex active cooling systems.This study presents a computational investigation of a novel Multi-Focal Pyramidal Array(MFPA)-based CPV system designed to overcome this limitation.The MFPA architecture employs a geometrically optimized pyramidal concentrator to distribute concen-trated sunlight onto strategically placed,low-cost monocrystalline silicon cells,enabling high efficiency energy capture while passively managing thermal loads.Coupled optical thermal electrical simulations in COMSOL Multiphysics demonstrate a geometric concentration ratio of 120×,with system temperatures maintained below 110℃ under standard 1000 W/m2 Direct Normal Irradiance(DNI).Ray tracing confirms 95%optical efficiency and a concentrated light spot radius of 2.48 mm.Compared with conventional CPV designs,the MFPA improves power-per-cost by 25%and reduces tracking requirements by 50%owing to its wide±15°acceptance angle.These results highlight the MFPA’s potential as a scalable,low-cost,and energy-efficient pathway for expanding solar power generation.展开更多
Within the prefrontal-cingulate cortex,abnormalities in coupling between neuronal networks can disturb the emotion-cognition interactions,contributing to the development of mental disorders such as depression.Despite ...Within the prefrontal-cingulate cortex,abnormalities in coupling between neuronal networks can disturb the emotion-cognition interactions,contributing to the development of mental disorders such as depression.Despite this understanding,the neural circuit mechanisms underlying this phenomenon remain elusive.In this study,we present a biophysical computational model encompassing three crucial regions,including the dorsolateral prefrontal cortex,subgenual anterior cingulate cortex,and ventromedial prefrontal cortex.The objective is to investigate the role of coupling relationships within the prefrontal-cingulate cortex networks in balancing emotions and cognitive processes.The numerical results confirm that coupled weights play a crucial role in the balance of emotional cognitive networks.Furthermore,our model predicts the pathogenic mechanism of depression resulting from abnormalities in the subgenual cortex,and network functionality was restored through intervention in the dorsolateral prefrontal cortex.This study utilizes computational modeling techniques to provide an insight explanation for the diagnosis and treatment of depression.展开更多
In Earth system modeling,the land surface is coupled with the atmosphere through surface turbulent fluxes.These fluxes are computed using mean meteorological variables between the surface and a reference height in the...In Earth system modeling,the land surface is coupled with the atmosphere through surface turbulent fluxes.These fluxes are computed using mean meteorological variables between the surface and a reference height in the atmosphere.However,the dependence of flux computation on the reference height,which is usually set as the lowest level in the atmosphere in Earth system models,has not received much attention.Based on high-resolution large-eddy simulation(LES)data under unstable conditions,we find the setting of reference height is not trivial within the framework of current surface layer theory.With a reasonable prescription of aerodynamic roughness length(following the setting in LESs),reference heights near the top of the surface layer tend to provide the best estimate of surface fluxes,especially for the momentum flux.Furthermore,this conclusion for the sensible heat flux is insensitive to the ratio of roughness length for momentum versus heat.These results are robust,whether using the classical or revised surface layer theory.They provide a potential guide for setting the proper reference heights for Earth system modeling and can be further tested in the near future using observational data from land–atmosphere feedback observatories.展开更多
Considering the influence of hydrogen gas generated during electrochemical machining on the conductivity of electrolyte, a two-phase turbulent flow model is presented to describe the gas bubbles distribution.The k-e t...Considering the influence of hydrogen gas generated during electrochemical machining on the conductivity of electrolyte, a two-phase turbulent flow model is presented to describe the gas bubbles distribution.The k-e turbulent model is used to describe the electrolyte flow field.The Euler–Euler model based on viscous drag and pressure force is used to calculate the twodimensional distribution of gas volume fraction.A multi-physics coupling model of electric field,two-phase flow field and temperature field is established and solved by weak coupling iteration method.The numerical simulation results of gas volume fraction, temperature and conductivity in equilibrium state are discussed.The distributions of machining gap at different time are analyzed.The predicted results of the machining gap are consistent with the experimental results, and the maximum deviation between them is less than 50 lm.展开更多
Interaction between the converter and the grid may lead to harmonic oscillations.The impedance-based method is an effective way to deal with the stability issue.In this study,the impedance-based method is used to inve...Interaction between the converter and the grid may lead to harmonic oscillations.The impedance-based method is an effective way to deal with the stability issue.In this study,the impedance-based method is used to investigate the small-signal stability of a cascaded 12-pulse line-commutated converter-based high-voltage direct current(LCC-HVDC)transmission system.In the modeling part,the impedance models of the single rectifier and inverter are established respectively with consideration to the effect of frequency coupling,which has improved the accuracy of the models.Based on the models,the AC impedance models of the cascaded LCC-HVDC transmission system are established both on the rectifier and inverter side.In the stability analysis part,the stability of the system is analyzed under different working conditions.The simulation results reveal that the established impedance model can properly represent the stability of this system.The findings of this study can provide a theoretical reference for the stability design and oscillation suppression strategy of LCC-HVDC transmission systems and LCC interconnected systems.展开更多
To investigate the effects of water and cyclic loading on dolomite’s mechanical properties during deep mining,mechanical experiments on non-pressure water absorption and cyclic loading were conducted.The findings rev...To investigate the effects of water and cyclic loading on dolomite’s mechanical properties during deep mining,mechanical experiments on non-pressure water absorption and cyclic loading were conducted.The findings reveal that the elastic modulus and Poisson ratio of dolomite fluctuate with increasing water content.The mass of water absorption is positively correlated with time and the water absorption stage can be divided into three stages:accelerated,decelerated,and stabilized stages.During this process,the number of pores in dolomite increases,while the pore diameter initially decreases and then fluctuates.Microscopic analysis shows that the proportion of mesopores first increases and then decreases,while micropores exhibit the opposite trend,and the proportion of macropores fluctuates around 0%.A model diagram of structural evolution during water absorption has been developed.Additionally,the softening process of dolomite’s water absorption strength is categorized into three stages:a relatively stable stage,an accelerated softening stage dominated by mesopore water absorption,and a decelerated softening stage characterized by micropore water absorption.A uniaxial damage constitutive model for dolomite under water influence was established based on the Weibull distribution and Mohr-Coulomb strength criterion,and experimental validation indicates its strong applicability.展开更多
High-voltage electric pulse(HVEP)rock fragmentation has demonstrated substantial potential for sustainable fracturing of hard rocks owing to its energy efficiency.The transient nature and highly disruptive characteris...High-voltage electric pulse(HVEP)rock fragmentation has demonstrated substantial potential for sustainable fracturing of hard rocks owing to its energy efficiency.The transient nature and highly disruptive characteristics of its physical fracturing process render experimental investigation of the underlying rock-breaking mechanisms challenging.However,existing numerical studies lack comprehensive models that precisely link electrical breakdown phenomena with mechanical disintegration processes.This study combines COMSOL electrical breakdown simulations with four-dimension lattice spring model(4D-LSM)mechanical analysis to establish a coupled HVEP rock fragmentation model.The core concept of the model construction is to import the temperature field of the plasma channel obtained from the electrical breakdown into the mechanical solver to realize the precise connection between the two stages.The validated numerical model elucidates the full process of HVEP-induced fragmentation under varying electrical parameters.Furthermore,the effects of confining pressure and mineral grain size on fragmentation behavior have been investigated.Finally,parametric simulations across 25 electrical parameter combinations demonstrate the critical role of electrode spacing optimization in achieving energy-efficient rock fragmentation.These findings provide a predictive tool for designing efficient HVEP systems in deep resource extraction and mineral processing engineering.展开更多
To reveal the influence of coupled effects of dry-wet cycling and precompression stress(CEDWCPS)on the damage evolution of limestone with horizontal fissure(LHF),a series of degradation and uniaxial compression tests ...To reveal the influence of coupled effects of dry-wet cycling and precompression stress(CEDWCPS)on the damage evolution of limestone with horizontal fissure(LHF),a series of degradation and uniaxial compression tests were conducted,and a corresponding piecewise damage constitutive model(PDCM)was established.We found that both dry-wet cycling and precompression stress deteriorate the physical properties,alter the microscopic characteristics,and reduce the mechanical properties of the LHF.These degradations are particularly pronounced under the CEDWCPS,although the magnitude of these changes gradually diminishes with the progression of dry-wet cycling.Meanwhile,they also reduce the deformation degree,prolong the micropore compaction stage,shorten the unstable crack propagation stage,lower the frequency and intensity of AE events,decrease the high-amplitude and high-frequency AE signals,enlarge crack scales,and shorten the crack initiation time.Among the changes of these indicators,the dry-wet cycling plays a dominant role.The crack types of LHF under the CEDWCPS(LHFCEDWCPS)are predominantly tensile cracks,supplemented by shear cracks.The failure mode can be defined as tensileshear composite failure.Finally,the established PDCM effectively captures the nonlinear deformation of micropore and the linear deformation of the matrix in LHFCEDWCPS,with all corresponding R^(2) consistently exceeding 0.97.展开更多
Prediction of permeability changes in surrounding rock induced by engineering disturbances is crucial for mitigating tunnel water inrush accidents.This study investigates the progressive failure characteristics and pe...Prediction of permeability changes in surrounding rock induced by engineering disturbances is crucial for mitigating tunnel water inrush accidents.This study investigates the progressive failure characteristics and permeability evolution of hard and soft rocks subjected to triaxial compression.A series of laboratory tests were conducted at confining pressures ranging from 4 to 20 MPa.Experimental results demonstrate that rock permeability variation with strain shows three distinct stages:an initial decrease,a stage of rapid mutation,and a postpeak increase.The concept of critical permeability barrier strength is introduced,representing the stress level at which continuous fracture formation enables significant seepage.Furthermore,two generalized permeability–stress models are developed for soft and hard rocks.The predicted permeability values obtained from these models align well with the experimental data.These findings offer valuable insights into the hydro-mechanical coupling behavior of rocks,providing a foundation for safe construction practices in underground engineering.展开更多
Coupled thermo-hydro-mechanical(THM)processes in fractured rock are playing a crucial role in geoscience and geoengineering applications.Diverse and conceptually distinct approaches have emerged over the past decades ...Coupled thermo-hydro-mechanical(THM)processes in fractured rock are playing a crucial role in geoscience and geoengineering applications.Diverse and conceptually distinct approaches have emerged over the past decades in both continuum and discontinuum perspectives leading to significant progress in their comprehending and modeling.This review paper offers an integrated perspective on existing modeling methodologies providing guidance for model selection based on the initial and boundary conditions.By comparing various models,one can better assess the uncertainties in predictions,particularly those related to the conceptual models.The review explores how these methodologies have significantlyenhanced the fundamental understanding of how fractures respond to fluid injection and production,and improved predictive capabilities pertaining to coupled processes within fractured systems.It emphasizes the importance of utilizing advanced computational technologies and thoroughly considering fundamental theories and principles established through past experimental evidence and practical experience.The selection and calibration of model parameters should be based on typical ranges and applied to the specificconditions of applications.The challenges arising from inherent heterogeneity and uncertainties,nonlinear THM coupled processes,scale dependence,and computational limitations in representing fieldscale fractures are discussed.Realizing potential advances on computational capacity calls for methodical conceptualization,mathematical modeling,selection of numerical solution strategies,implementation,and calibration to foster simulation outcomes that intricately reflectthe nuanced complexities of geological phenomena.Future research efforts should focus on innovative approaches to tackle the hurdles and advance the state-of-the-art in this critical fieldof study.展开更多
A mechanistic understanding and modeling of the coupled human and natural systems(CHANS)are frontier of geographical sciences and essential for promoting regional sustainability.Modeling regional CHANS in the Yellow R...A mechanistic understanding and modeling of the coupled human and natural systems(CHANS)are frontier of geographical sciences and essential for promoting regional sustainability.Modeling regional CHANS in the Yellow River Basin(YRB)featuring high water stress,intense human interference,and a fragile ecosystem has always been a complex challenge.Here,we propose a conceptual modeling framework to capture key human-natural components and their interactions,focusing on human-water dynamics.The modeling framework encompasses five human(Population,Economy,Energy,Food,and Water Demand)and five natural sectors(Water Supply,Sediment,Land,Carbon,and Climate)that can be either fully interactive or standalone.The modeling framework,implemented using the system dynamics(SD)approach,can well reproduce the basin's historical evolution in human-natural processes and predict future dynamics under various scenarios.The flexibility,adaptability,and potential for integration with diverse methods position the framework as an instructive tool for guiding regional CHANS modeling.Our insights highlight pathways to advance regional CHANS modeling and its application to address regional sustainability challenges.展开更多
Inspired by the crucial role of the tail in crocodile locomotion,we propose a novel rigid-flexible coupled tail structure design.The tail design reduces the number of required actuators,enables undulatory propulsion i...Inspired by the crucial role of the tail in crocodile locomotion,we propose a novel rigid-flexible coupled tail structure design.The tail design reduces the number of required actuators,enables undulatory propulsion in swimming,and provides additional support during terrestrial crawling.However,when the tail lifts off the ground during land crawling,its flexible underactuated structure tends to oscillate randomly due to minimal damping.These oscillations impart disruptive reaction torques to the body,critically impairing locomotion stability.To tackle this issue,we employed the standard Denavit-Hartenberg(DH)method and Newton-Euler equations to formulate a rigid-flexible coupled dynamic model for the tail,in which distributed elastic forces are embedded as internal forces in the force balance equations.Based on this model,we propose an oscillation suppression strategy based on an energy-optimized Nonlinear Model Predictive Controller(NMPC)with a single joint torque as the control input.This controller solves a constrained multi-objective optimization problem to effectively suppress the underactuated oscillations of the tail.Finally,experimental comparisons validate the accuracy of the dynamic model,and simulations based on this model substantiate the effectiveness of the oscillation suppression strategy.展开更多
With the miniaturization of devices and the development of modern heating technologies,the generalization of heat conduction and thermoelastic coupling has become crucial,effectively emulating the thermodynamic behavi...With the miniaturization of devices and the development of modern heating technologies,the generalization of heat conduction and thermoelastic coupling has become crucial,effectively emulating the thermodynamic behavior of materials in ultrashort time scales.Theoretically,generalized heat conductive models are considered in this work.By analogy with mechanical viscoelastic models,this paper further enriches the heat conduction models and gives their one-dimensional physical expression.Numerically,the transient thermoelastic response of the slim strip material under thermal shock is investigated by applying the proposed models.First,the analytical solution in the Laplace domain is obtained by the Laplace transform.Then,the numerical results of the transient responses are obtained by the numerical inverse Laplace transform.Finally,the transient responses of different models are analyzed and compared,and the effects of material parameters are discussed.This work not only opens up new research perspectives on generalized heat conductive and thermoelastic coupling theories,but also is expected to be beneficial for the deeper understanding of the heat wave theory.展开更多
In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and t...In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and the NDK code is a neutron diffusion code.The coupling program framework adopts the"master-slave"mode,in which Fluent is the master program while NDK and KMC-sub are coupled internally and compiled into the dynamic link library(DLL)as slave codes.The domain decomposition method was adopted,in which the reactor core was simulated by NDK and KMC-sub,while the rest of the primary loop was simulated using Fluent.A simulation of the reactor shutdown process of M2LFR-1000 was carried out using the coupling program,and the code-to-code verification was performed with ATHLET,demonstrating a good agreement,with absolute deviation was smaller than 0.2%.The results show an obvious thermal stratification phenomenon during the shutdown process,which occurs 10 s after shutdown,and the change in thermal stratification phenomena is also captured by the coupling program.At the same time,the change in the neutron flux density distribution of the reactor was also obtained.展开更多
Coastal cities hold a special position in the fields of production,living,and ecological research because of their unique wetland resource advantages.However,with global urbanization and rapid economic development,con...Coastal cities hold a special position in the fields of production,living,and ecological research because of their unique wetland resource advantages.However,with global urbanization and rapid economic development,con-flicts among production,living and ecological land are prevalent in coastal cities in the process of maintaining sustainable wetland resources and further developing the social economy.By establishing an SD-PLUS-CCD cou-pling model,this paper analysed the evolution characteristics and driving mechanism of the production-living-ecological space(PLES)and the effects of wetland protection(WLP)on promoting or inhibiting the coordinated development of the PLES in Dongying city during 2005-2060.The results show that(1)from 2005 to 2020,the increase in urban population resulted in a significant transfer of arable land and a reduction of 914 km2 in pro-duction space(PS);(2)from 2020 to 2060,under the WLP scenario,the conversion of wetland ecological space will reduce the PS and living space(LS)by 193.92 km2 and 107.14 km2,respectively,and increase the ecological space(ES)by 327.52 km2;and(3)wetland protection has an inhibitory effect on the coordinated development of PLES in the study area,and the total proportion of noncoordinated areas of PE and living-ecological space will continue to increase during the simulation period.This paper provides a solid theoretical support for the sustain-able management and protection of wetlands in coastal cities and possible PLES conflict patterns and provides a scientific basis for future territorial spatial planning and policy balance analysis.展开更多
Improving the absorbed gas to active desorption and seepage and delaying gas drainage attenuation are considered as key methods for increasing drainage efficiency and gas output.According to the solid mechanics theory...Improving the absorbed gas to active desorption and seepage and delaying gas drainage attenuation are considered as key methods for increasing drainage efficiency and gas output.According to the solid mechanics theory,the nonlinear Darcy seepage theory and thermodynamics,the heat-fluid-solid coupling model for gassy coal has been improved.The numerical model was founded from the improved multi-field coupling model by COMSOL Multiphysics and gas drainage by borehole down the coal seam enhanced by heat injection was modelled.The results show that the heatfluid-solid model with adsorption effects for gassy coal was well simulated by the improved multi-field model.The mechanism of coal seam gas desorption seepage under the combined action of temperature,stress and adsorption can be well described.Gas desorption and seepage can be enhanced by heat injection into coal seams.The gas drainage rate was directly proportional to the temperature of injected heat in the scope of 30-150 ℃ and increasing in the whole modelleddrainage process (0-1000 d).The increased level was maximum in the initial drainage time and decreasing gradually along with drainage time.The increasing ratio of drainage rate was maximum when the temperature raised from 30 to 60 ℃.Although the drainage rate would increase along with increasing temperature,when exceeding 60 ℃,the increasing ratio of drainage rate with rising temperature would decrease.Gas drainage promotion was more effective in coal seams with lower permeability than with higher permeability.The coal seam temperature in a 5 m distance surrounding the heat injection borehole would rise to around 60 ℃ in 3 months.That was much less than the time of gas drainage in the coal mines in sites with low permeability coal seams.Therefore,it is valuable and feasible to inject heat into coal seams to promote gas drainage,and this has strong feasibility for coal seams with low permeability which are widespread in China.展开更多
The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computatio...The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computational fluid dynamics and the flexible rod dynamics is proposed using a two-way domain expansion method.The gov-erning equations of the flexible rod dynamics are discretized and solved by the finite element method,and the fluid flow is simulated by the finite volume method.The interaction between fluids and solid rods is modeled by introducing body force terms into the momentum equations.Referred to the traditional semi-resolved numerical model,an anisotropic Gaussian kernel function method is proposed to specify the interactive forces between flu-ids and solid bodies for non-circle rod cross-sections.A benchmark of the flow passing around a single flexible plate with a rectangular cross-section is used to validate the algorithm.Focused on the engineering applications,a test case of a finite patch of cylinders is implemented to validate the accuracy and efficiency of the coupled model.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12272411 and 42007259).
文摘Deep rock engineering is affected by coupled thermo-hydro-mechanical(THM)-dynamic fields,necessitating the elucidation of the dynamic mechanical behavior and failure mechanisms.This study utilized a Multi-field Coupled Controlled Split Hopkinson Pressure Bar(MCC-SHPB)system to elucidate the cross-scale dynamic responses of rocks and the boundaries of failure modes under THM coupling.Impact tests were conducted on green sandstone under coupled conditions of temperature(25℃-80℃),confining pressure(0-15 MPa),and seepage water pressure(0-15 MPa).Scanning electron microscopy(SEM)microstructural characterization and COMSOL Multiphysics numerical simulations were conducted,and a dynamic constitutive theoretical framework and failure-prediction methodology were established.We investigated the impact toughness index(I_(t)),dynamic modulus(E_(d)),dynamic triaxial compressive strength(TCS_(d)),fragmentation degree(W),and failure modes of green sandstone under thermo-confining pressure-seepage-impact loading conditions.The key findings reveal that the(I_(t))reflects different energy regulation mechanisms across different confining pressure regimes.Thermal-microcrack interactions dominate at low pressure,and energy absorption prevails at high pressure.A triphasic dynamic modulus model captures stiffness evolution under energy-driven conditions,revealing cross-scale crack nucleation-propagation and fragment reorganization.The TCSd inflection point signifies energy dissipation shifts,causing nonlinear skeleton bearing-capacity degradation.A critical criterion based on the W was established to distinguish between the two failure modes and predict the unstable failure initiation.Numerical simulations were used to elucidate the effects of inertia-dominated crack propagation and stress wave interference,validating the critical criterion and the predictive accuracy of the theoretical model during cross-scale failure.This study provides a theoretical foundation for assessing the dynamic stability of rock masses subjected to multi-field coupling during deep resource exploitation.
基金supported by the National Key R&D Program of China(No.2021YFB2011300)the National Natural Science Foundation of China(Nos.52275044,U2233212)。
文摘The Electro–Hydrostatic Actuator(EHA)is applied to drive the control surface in flightcontrol system of more electric aircraft.In EHA,the Oil-Immersed Motor Pump(OMP)serves asthe core as a power assembly.However,the compact integration of the OMP presents challenges inefficiently dissipating internal heat,leading to a performance degradation of the EHA due to ele-vated temperatures.Therefore,accurately modeling and predicting the internal thermal dynamicsof the OMP hold considerable significance for monitoring the operational condition of the EHA.In view of this,a modeling method considering cumulative thermal coupling was hereby proposed.Based on the proposed method,the thermal models of the motor and the pump were established,taking into account heat accumulation and transfer.Taking the leakage oil as the heat couplingpoint between the motor and the pump,the dynamic thermal coupling model of the OMP wasdeveloped,with the thermal characteristics of the oil considered.Additionally,the comparativeexperiments were conducted to illustrate the efficiency of the proposed model.The experimentalresults demonstrate that the proposed dynamic thermal coupling model accurately captured thethermal behavior of OMP,outperforming the static thermal parameter model.Overall,thisadvancement is crucial for effectively monitoring the health of EHA and ensuring flight safety.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2025YFE0110100)Xjenza Malta through SINOMALTA-2024-11(Science and Technology Cooperation)+8 种基金National Natural Science Foundation of China(52165043)Jiang Xi Provincial Natural Science Foundation of China(20224ACB214008,20232BAB214007)Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects(20225BCJ23008)Excellent Research and Innovation Team in Anhui Province(2024AH010031)The University Synergy Innovation Program of Anhui Province(GXXT-2023-025,GXXT-2023-026)Anhui Province Science and Technology Innovation Tackle Plan Project of Anhui Province(202423i08050011)Anhui Provincial Natural Science Foundation of China(2308085ME171)The Project for Cultivating Academic(or Disciplinary)Leaders of Anhui University(DTR2024044)Talent research start-up fund project(2024tlxyrc056).
文摘Laser powder bed fusion(LPBF)has revolutionized modern manufacturing by enabling high design freedom,rapid prototyping,and tailored mechanical properties.However,optimizing process parameters remains challenging due to the trial-and-error approaches required to capture subtle parameter-microstructure relationships.This study employed a multi-physics computational framework to investigate the melting and solidification dynamics of magnesium alloy.By integrating the discrete element method for powder bed generation,finite volume method with volume of fluid for melt pool behavior,and phase-field method for microstructural evolution,the critical physical phenomena,including powder melting,molten pool flow,and directional solidification were simulated.The effects of laser power and scanning speed on temperature distribution,melt pool geometry,and dendritic morphology were systematically analyzed.It was revealed that increasing laser power expanded melt pool dimensions and promoted columnar dendritic growth,while high scanning speeds reduced melt pool stability and refined dendritic structures.Furthermore,Marangoni convection and thermal gradients governed solute redistribution,with excessive energy input risking defects such as porosity and elemental evaporation.These insights establish quantitative correlations between process parameters,thermal history,and microstructural characteristics,providing a validated roadmap for LPBF-processed magnesium alloy with tailored performance.
文摘Conventional concentrator photovoltaics(CPV)face a persistent trade-off between high efficiency and high cost,driven by expensive multi-junction solar cells and complex active cooling systems.This study presents a computational investigation of a novel Multi-Focal Pyramidal Array(MFPA)-based CPV system designed to overcome this limitation.The MFPA architecture employs a geometrically optimized pyramidal concentrator to distribute concen-trated sunlight onto strategically placed,low-cost monocrystalline silicon cells,enabling high efficiency energy capture while passively managing thermal loads.Coupled optical thermal electrical simulations in COMSOL Multiphysics demonstrate a geometric concentration ratio of 120×,with system temperatures maintained below 110℃ under standard 1000 W/m2 Direct Normal Irradiance(DNI).Ray tracing confirms 95%optical efficiency and a concentrated light spot radius of 2.48 mm.Compared with conventional CPV designs,the MFPA improves power-per-cost by 25%and reduces tracking requirements by 50%owing to its wide±15°acceptance angle.These results highlight the MFPA’s potential as a scalable,low-cost,and energy-efficient pathway for expanding solar power generation.
基金supported by the Major Research Instrument Development Project of the National Natural Science Foundation of China(82327810)the Foundation of the President of Hebei University(XZJJ202202)the Hebei Province“333 talent project”(A202101058).
文摘Within the prefrontal-cingulate cortex,abnormalities in coupling between neuronal networks can disturb the emotion-cognition interactions,contributing to the development of mental disorders such as depression.Despite this understanding,the neural circuit mechanisms underlying this phenomenon remain elusive.In this study,we present a biophysical computational model encompassing three crucial regions,including the dorsolateral prefrontal cortex,subgenual anterior cingulate cortex,and ventromedial prefrontal cortex.The objective is to investigate the role of coupling relationships within the prefrontal-cingulate cortex networks in balancing emotions and cognitive processes.The numerical results confirm that coupled weights play a crucial role in the balance of emotional cognitive networks.Furthermore,our model predicts the pathogenic mechanism of depression resulting from abnormalities in the subgenual cortex,and network functionality was restored through intervention in the dorsolateral prefrontal cortex.This study utilizes computational modeling techniques to provide an insight explanation for the diagnosis and treatment of depression.
基金supported by the Natural Science Foundation of China(Grant Nos.42088101 and 42375163)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030007)the specific research fund of The Innovation Platform for Academicians of Hainan Province(Grant No.YSPTZX202143)。
文摘In Earth system modeling,the land surface is coupled with the atmosphere through surface turbulent fluxes.These fluxes are computed using mean meteorological variables between the surface and a reference height in the atmosphere.However,the dependence of flux computation on the reference height,which is usually set as the lowest level in the atmosphere in Earth system models,has not received much attention.Based on high-resolution large-eddy simulation(LES)data under unstable conditions,we find the setting of reference height is not trivial within the framework of current surface layer theory.With a reasonable prescription of aerodynamic roughness length(following the setting in LESs),reference heights near the top of the surface layer tend to provide the best estimate of surface fluxes,especially for the momentum flux.Furthermore,this conclusion for the sensible heat flux is insensitive to the ratio of roughness length for momentum versus heat.These results are robust,whether using the classical or revised surface layer theory.They provide a potential guide for setting the proper reference heights for Earth system modeling and can be further tested in the near future using observational data from land–atmosphere feedback observatories.
基金funded by the National Natural Science Foundation of China(Nos.51775161 and 51775158)。
文摘Considering the influence of hydrogen gas generated during electrochemical machining on the conductivity of electrolyte, a two-phase turbulent flow model is presented to describe the gas bubbles distribution.The k-e turbulent model is used to describe the electrolyte flow field.The Euler–Euler model based on viscous drag and pressure force is used to calculate the twodimensional distribution of gas volume fraction.A multi-physics coupling model of electric field,two-phase flow field and temperature field is established and solved by weak coupling iteration method.The numerical simulation results of gas volume fraction, temperature and conductivity in equilibrium state are discussed.The distributions of machining gap at different time are analyzed.The predicted results of the machining gap are consistent with the experimental results, and the maximum deviation between them is less than 50 lm.
基金supported in part by the National Natural Science Foundation of China under 52125704 and 51937001.
文摘Interaction between the converter and the grid may lead to harmonic oscillations.The impedance-based method is an effective way to deal with the stability issue.In this study,the impedance-based method is used to investigate the small-signal stability of a cascaded 12-pulse line-commutated converter-based high-voltage direct current(LCC-HVDC)transmission system.In the modeling part,the impedance models of the single rectifier and inverter are established respectively with consideration to the effect of frequency coupling,which has improved the accuracy of the models.Based on the models,the AC impedance models of the cascaded LCC-HVDC transmission system are established both on the rectifier and inverter side.In the stability analysis part,the stability of the system is analyzed under different working conditions.The simulation results reveal that the established impedance model can properly represent the stability of this system.The findings of this study can provide a theoretical reference for the stability design and oscillation suppression strategy of LCC-HVDC transmission systems and LCC interconnected systems.
基金Project(IMRI23005)supported by Ordos Science and Technology Bureau,ChinaProjects(52174096,52304110)supported by the National Natural Science Foundation of China。
文摘To investigate the effects of water and cyclic loading on dolomite’s mechanical properties during deep mining,mechanical experiments on non-pressure water absorption and cyclic loading were conducted.The findings reveal that the elastic modulus and Poisson ratio of dolomite fluctuate with increasing water content.The mass of water absorption is positively correlated with time and the water absorption stage can be divided into three stages:accelerated,decelerated,and stabilized stages.During this process,the number of pores in dolomite increases,while the pore diameter initially decreases and then fluctuates.Microscopic analysis shows that the proportion of mesopores first increases and then decreases,while micropores exhibit the opposite trend,and the proportion of macropores fluctuates around 0%.A model diagram of structural evolution during water absorption has been developed.Additionally,the softening process of dolomite’s water absorption strength is categorized into three stages:a relatively stable stage,an accelerated softening stage dominated by mesopore water absorption,and a decelerated softening stage characterized by micropore water absorption.A uniaxial damage constitutive model for dolomite under water influence was established based on the Weibull distribution and Mohr-Coulomb strength criterion,and experimental validation indicates its strong applicability.
基金financial support from the National Natural Science Foundation of China(Nos.52209144 and 12472405).
文摘High-voltage electric pulse(HVEP)rock fragmentation has demonstrated substantial potential for sustainable fracturing of hard rocks owing to its energy efficiency.The transient nature and highly disruptive characteristics of its physical fracturing process render experimental investigation of the underlying rock-breaking mechanisms challenging.However,existing numerical studies lack comprehensive models that precisely link electrical breakdown phenomena with mechanical disintegration processes.This study combines COMSOL electrical breakdown simulations with four-dimension lattice spring model(4D-LSM)mechanical analysis to establish a coupled HVEP rock fragmentation model.The core concept of the model construction is to import the temperature field of the plasma channel obtained from the electrical breakdown into the mechanical solver to realize the precise connection between the two stages.The validated numerical model elucidates the full process of HVEP-induced fragmentation under varying electrical parameters.Furthermore,the effects of confining pressure and mineral grain size on fragmentation behavior have been investigated.Finally,parametric simulations across 25 electrical parameter combinations demonstrate the critical role of electrode spacing optimization in achieving energy-efficient rock fragmentation.These findings provide a predictive tool for designing efficient HVEP systems in deep resource extraction and mineral processing engineering.
基金supported by the Yunnan Province Science and Technology Plan Project(No.202403AA080001-4)the Key Research and Development Project of Guangxi,China(No.guikeAB24010144)the National Key Research and Development Project of China(Nos.2021YFB3901402 and 2018YFC1504802)。
文摘To reveal the influence of coupled effects of dry-wet cycling and precompression stress(CEDWCPS)on the damage evolution of limestone with horizontal fissure(LHF),a series of degradation and uniaxial compression tests were conducted,and a corresponding piecewise damage constitutive model(PDCM)was established.We found that both dry-wet cycling and precompression stress deteriorate the physical properties,alter the microscopic characteristics,and reduce the mechanical properties of the LHF.These degradations are particularly pronounced under the CEDWCPS,although the magnitude of these changes gradually diminishes with the progression of dry-wet cycling.Meanwhile,they also reduce the deformation degree,prolong the micropore compaction stage,shorten the unstable crack propagation stage,lower the frequency and intensity of AE events,decrease the high-amplitude and high-frequency AE signals,enlarge crack scales,and shorten the crack initiation time.Among the changes of these indicators,the dry-wet cycling plays a dominant role.The crack types of LHF under the CEDWCPS(LHFCEDWCPS)are predominantly tensile cracks,supplemented by shear cracks.The failure mode can be defined as tensileshear composite failure.Finally,the established PDCM effectively captures the nonlinear deformation of micropore and the linear deformation of the matrix in LHFCEDWCPS,with all corresponding R^(2) consistently exceeding 0.97.
基金National Natural Science Foundation of China,Grant/Award Numbers:52274082,42307244,42230704Jiangxi Provincial Natural Science Foundation,Grant/Award Number:2024BAB26047+3 种基金Innovative Experts,Long-term Program of Jiangxi Province,Grant/Award Number:jxsq2018106049Opening Foundation of Anhui Province Key Laboratory of Building Structure and Underground Engineering,Grant/Award Number:KLBSUE‐2022‐04Program of Qingjiang Excellent Young Talents of Jiangxi University of Science and Technology,Grant/Award Number:JXUSTQJBJ2020003Fundamental Research Funds for the Central Universities,Grant/Award Number:2023QN1024。
文摘Prediction of permeability changes in surrounding rock induced by engineering disturbances is crucial for mitigating tunnel water inrush accidents.This study investigates the progressive failure characteristics and permeability evolution of hard and soft rocks subjected to triaxial compression.A series of laboratory tests were conducted at confining pressures ranging from 4 to 20 MPa.Experimental results demonstrate that rock permeability variation with strain shows three distinct stages:an initial decrease,a stage of rapid mutation,and a postpeak increase.The concept of critical permeability barrier strength is introduced,representing the stress level at which continuous fracture formation enables significant seepage.Furthermore,two generalized permeability–stress models are developed for soft and hard rocks.The predicted permeability values obtained from these models align well with the experimental data.These findings offer valuable insights into the hydro-mechanical coupling behavior of rocks,providing a foundation for safe construction practices in underground engineering.
基金funding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Program through the Starting Grant GEoREST(grant agreement No.801809)support by MICIU/AEI/10.13039/501100011033 and by"European Union Next Generation EU/PRTR"through the‘Ramón y Cajal’fellowship(reference RYC2021-032780-I)+9 种基金funding by MICIU/AEI/10.13039/501100011033 and by“ERDF,EU”through the‘HydroPoreII’project(reference PID2022-137652NBC44)support by the Institute for Korea Spent Nuclear Fuel(iKSNF)National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT,MSIT)(2021M2E1A1085196)support by the Swedish Radiation Safety(SSM),Swedish Transport Administration(Trafikverket),Swedish Rock Engineering Foundation(BeFo),and Nordic Energy Research(Grant 187658)supported by the US Department of Energy(DOE),the Officeof Nuclear Energy,Spent Fuel and Waste Science and Technology Campaign,and by the US Department of Energy(DOE),the Office of Basic Energy Sciences,Chemical Sciences,Geosciences,and Biosciences Division both under Contract Number DE-AC02-05CH11231 with Lawrence Berkeley National Laboratorysupport from the US National Science Foundation(grant CMMI-2239630)funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(grant agreement No.101002507)the UK Natural Environment Research Council(NERC)for funding SeisGreen Project(Grant No.NE/W009293/1)which supported this workthe Royal Society UK for supporting this research through fellowship UF160443IMEDEA is an accredited"Maria de Maeztu Excellence Unit"(Grant CEX2021-001198,funded by MICIU/AEI/10.13039/501100011033).
文摘Coupled thermo-hydro-mechanical(THM)processes in fractured rock are playing a crucial role in geoscience and geoengineering applications.Diverse and conceptually distinct approaches have emerged over the past decades in both continuum and discontinuum perspectives leading to significant progress in their comprehending and modeling.This review paper offers an integrated perspective on existing modeling methodologies providing guidance for model selection based on the initial and boundary conditions.By comparing various models,one can better assess the uncertainties in predictions,particularly those related to the conceptual models.The review explores how these methodologies have significantlyenhanced the fundamental understanding of how fractures respond to fluid injection and production,and improved predictive capabilities pertaining to coupled processes within fractured systems.It emphasizes the importance of utilizing advanced computational technologies and thoroughly considering fundamental theories and principles established through past experimental evidence and practical experience.The selection and calibration of model parameters should be based on typical ranges and applied to the specificconditions of applications.The challenges arising from inherent heterogeneity and uncertainties,nonlinear THM coupled processes,scale dependence,and computational limitations in representing fieldscale fractures are discussed.Realizing potential advances on computational capacity calls for methodical conceptualization,mathematical modeling,selection of numerical solution strategies,implementation,and calibration to foster simulation outcomes that intricately reflectthe nuanced complexities of geological phenomena.Future research efforts should focus on innovative approaches to tackle the hurdles and advance the state-of-the-art in this critical fieldof study.
基金supported by the National Natural Science Foundation of China(Grant No.42041007)the Fundamental Research Funds for the Central Universities。
文摘A mechanistic understanding and modeling of the coupled human and natural systems(CHANS)are frontier of geographical sciences and essential for promoting regional sustainability.Modeling regional CHANS in the Yellow River Basin(YRB)featuring high water stress,intense human interference,and a fragile ecosystem has always been a complex challenge.Here,we propose a conceptual modeling framework to capture key human-natural components and their interactions,focusing on human-water dynamics.The modeling framework encompasses five human(Population,Economy,Energy,Food,and Water Demand)and five natural sectors(Water Supply,Sediment,Land,Carbon,and Climate)that can be either fully interactive or standalone.The modeling framework,implemented using the system dynamics(SD)approach,can well reproduce the basin's historical evolution in human-natural processes and predict future dynamics under various scenarios.The flexibility,adaptability,and potential for integration with diverse methods position the framework as an instructive tool for guiding regional CHANS modeling.Our insights highlight pathways to advance regional CHANS modeling and its application to address regional sustainability challenges.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFB3213600).
文摘Inspired by the crucial role of the tail in crocodile locomotion,we propose a novel rigid-flexible coupled tail structure design.The tail design reduces the number of required actuators,enables undulatory propulsion in swimming,and provides additional support during terrestrial crawling.However,when the tail lifts off the ground during land crawling,its flexible underactuated structure tends to oscillate randomly due to minimal damping.These oscillations impart disruptive reaction torques to the body,critically impairing locomotion stability.To tackle this issue,we employed the standard Denavit-Hartenberg(DH)method and Newton-Euler equations to formulate a rigid-flexible coupled dynamic model for the tail,in which distributed elastic forces are embedded as internal forces in the force balance equations.Based on this model,we propose an oscillation suppression strategy based on an energy-optimized Nonlinear Model Predictive Controller(NMPC)with a single joint torque as the control input.This controller solves a constrained multi-objective optimization problem to effectively suppress the underactuated oscillations of the tail.Finally,experimental comparisons validate the accuracy of the dynamic model,and simulations based on this model substantiate the effectiveness of the oscillation suppression strategy.
基金Project supported by the Guangdong Basic and Applied Basic Research Foundation of China(No.2023A1515012809)the Natural Science Foundation of Shaanxi Province of China(No.2023-JC-YB-073)the Fundamental Research Funds for the Central Universities of China(No.D5000230066)。
文摘With the miniaturization of devices and the development of modern heating technologies,the generalization of heat conduction and thermoelastic coupling has become crucial,effectively emulating the thermodynamic behavior of materials in ultrashort time scales.Theoretically,generalized heat conductive models are considered in this work.By analogy with mechanical viscoelastic models,this paper further enriches the heat conduction models and gives their one-dimensional physical expression.Numerically,the transient thermoelastic response of the slim strip material under thermal shock is investigated by applying the proposed models.First,the analytical solution in the Laplace domain is obtained by the Laplace transform.Then,the numerical results of the transient responses are obtained by the numerical inverse Laplace transform.Finally,the transient responses of different models are analyzed and compared,and the effects of material parameters are discussed.This work not only opens up new research perspectives on generalized heat conductive and thermoelastic coupling theories,but also is expected to be beneficial for the deeper understanding of the heat wave theory.
基金supported by Science and Technology on Reactor System Design Technology Laboratory,Chengdu,China(LRSDT2020106)
文摘In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and the NDK code is a neutron diffusion code.The coupling program framework adopts the"master-slave"mode,in which Fluent is the master program while NDK and KMC-sub are coupled internally and compiled into the dynamic link library(DLL)as slave codes.The domain decomposition method was adopted,in which the reactor core was simulated by NDK and KMC-sub,while the rest of the primary loop was simulated using Fluent.A simulation of the reactor shutdown process of M2LFR-1000 was carried out using the coupling program,and the code-to-code verification was performed with ATHLET,demonstrating a good agreement,with absolute deviation was smaller than 0.2%.The results show an obvious thermal stratification phenomenon during the shutdown process,which occurs 10 s after shutdown,and the change in thermal stratification phenomena is also captured by the coupling program.At the same time,the change in the neutron flux density distribution of the reactor was also obtained.
基金supported by the Joint Research program for Eco-logical Conservation and High-quality Development of the Yellow River Basin(Grant No.2022-YRUC-01-0103)Watershed Non-point Source Pollution Prevention and Control Technology and Application Demon-stration Project(Grant No.2021YFC3201505)+3 种基金the National Key Re-search and Development Project(Grant No.2016YFC0502106)the Natural Science Foundation of China(Grant No.41476161)the Spe-cial Project of National Natural Science Foundation of China(Grant No.42442035)the Fundamental Research Funds for the Central Uni-versities.
文摘Coastal cities hold a special position in the fields of production,living,and ecological research because of their unique wetland resource advantages.However,with global urbanization and rapid economic development,con-flicts among production,living and ecological land are prevalent in coastal cities in the process of maintaining sustainable wetland resources and further developing the social economy.By establishing an SD-PLUS-CCD cou-pling model,this paper analysed the evolution characteristics and driving mechanism of the production-living-ecological space(PLES)and the effects of wetland protection(WLP)on promoting or inhibiting the coordinated development of the PLES in Dongying city during 2005-2060.The results show that(1)from 2005 to 2020,the increase in urban population resulted in a significant transfer of arable land and a reduction of 914 km2 in pro-duction space(PS);(2)from 2020 to 2060,under the WLP scenario,the conversion of wetland ecological space will reduce the PS and living space(LS)by 193.92 km2 and 107.14 km2,respectively,and increase the ecological space(ES)by 327.52 km2;and(3)wetland protection has an inhibitory effect on the coordinated development of PLES in the study area,and the total proportion of noncoordinated areas of PE and living-ecological space will continue to increase during the simulation period.This paper provides a solid theoretical support for the sustain-able management and protection of wetlands in coastal cities and possible PLES conflict patterns and provides a scientific basis for future territorial spatial planning and policy balance analysis.
基金The authors acknowledge the financial support from the Natural Science Foundation of China(U1704131)Program for Science&Technology Innovation Talents in Universities of Henan Province(18HASTIT018)the Program for Changjiang Scholars and Innovative Research Team in University(IRT_16R22).
文摘Improving the absorbed gas to active desorption and seepage and delaying gas drainage attenuation are considered as key methods for increasing drainage efficiency and gas output.According to the solid mechanics theory,the nonlinear Darcy seepage theory and thermodynamics,the heat-fluid-solid coupling model for gassy coal has been improved.The numerical model was founded from the improved multi-field coupling model by COMSOL Multiphysics and gas drainage by borehole down the coal seam enhanced by heat injection was modelled.The results show that the heatfluid-solid model with adsorption effects for gassy coal was well simulated by the improved multi-field model.The mechanism of coal seam gas desorption seepage under the combined action of temperature,stress and adsorption can be well described.Gas desorption and seepage can be enhanced by heat injection into coal seams.The gas drainage rate was directly proportional to the temperature of injected heat in the scope of 30-150 ℃ and increasing in the whole modelleddrainage process (0-1000 d).The increased level was maximum in the initial drainage time and decreasing gradually along with drainage time.The increasing ratio of drainage rate was maximum when the temperature raised from 30 to 60 ℃.Although the drainage rate would increase along with increasing temperature,when exceeding 60 ℃,the increasing ratio of drainage rate with rising temperature would decrease.Gas drainage promotion was more effective in coal seams with lower permeability than with higher permeability.The coal seam temperature in a 5 m distance surrounding the heat injection borehole would rise to around 60 ℃ in 3 months.That was much less than the time of gas drainage in the coal mines in sites with low permeability coal seams.Therefore,it is valuable and feasible to inject heat into coal seams to promote gas drainage,and this has strong feasibility for coal seams with low permeability which are widespread in China.
基金supported by Shanghai 2021“Science and Technology Innovation Action Plan”:Social Development Science and Technology Research Project(Grant No.21DZ1202703).
文摘The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computational fluid dynamics and the flexible rod dynamics is proposed using a two-way domain expansion method.The gov-erning equations of the flexible rod dynamics are discretized and solved by the finite element method,and the fluid flow is simulated by the finite volume method.The interaction between fluids and solid rods is modeled by introducing body force terms into the momentum equations.Referred to the traditional semi-resolved numerical model,an anisotropic Gaussian kernel function method is proposed to specify the interactive forces between flu-ids and solid bodies for non-circle rod cross-sections.A benchmark of the flow passing around a single flexible plate with a rectangular cross-section is used to validate the algorithm.Focused on the engineering applications,a test case of a finite patch of cylinders is implemented to validate the accuracy and efficiency of the coupled model.
