Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
The F_(1)-ATPase and V_(1)-ATPase are rotary biomotors.Alignment of their amino acid sequences,which originate from bovine heart mitochondria(1BMF)and Enterococcus hirae(3VR6),respectively,demonstrates that the segmen...The F_(1)-ATPase and V_(1)-ATPase are rotary biomotors.Alignment of their amino acid sequences,which originate from bovine heart mitochondria(1BMF)and Enterococcus hirae(3VR6),respectively,demonstrates that the segment forming the ATP catalytic pocket is highly conserved.Single-molecule experiments,however,have revealed subtle differences in efficiency between the F_(1) and V_(1) motors.Here,we perform both atomistic and coarse-grained molecular dynamics simulations to investigate the mechanochemical coupling and coordination in F_(1) and V_(1) ATPase.Our results show that the correlation between conformational changes in F_(1) is stronger than that in V_(1),indicating that the mechanochemical coupling in F_(1) is tighter than in V_(1).Moreover,the unidirectional rotation of F_(1) is more processive than that of V_(1),which accounts for the higher efficiency observed in F_(1) and explains the occasional backward steps detected in single-molecule experiments on V_(1).展开更多
This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SE...This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SEM),which is used to simulate low-frequency ground motion(f<1 Hz)by incorporating an innovative efficient discontinuous Galerkin(DG)method for grid division to accurately model basin sedimentary layers at reduced costs.It also introduces a comprehensive hybrid source model for high-frequency random scattering and a nonlinear analysis module for basin sedimentary layers.Deterministic outcomes are combined with modified three-dimensional stochastic finite fault method(3D-EXSIM)simulations of high-frequency ground motion(f>1 Hz).A fourth-order Butterworth filter with zero phase shift is employed for time-domain filtering of low-and high-frequency time series at a crossover frequency of 1 Hz,merging the low and high-frequency ground motions into a broadband time series.Taking an Ms 6.8 Luding earthquake,as an example,this hybrid method was used for a rapid and efficient simulation analysis of broadband ground motion in the region.The accuracy and efficiency of this hybrid method were verified through comparisons with actually observed station data and empirical attenuation curves.Deterministic method simulation results revealed the effects of mountainous topography,basin effects,nonlinear effects within the basin’s sedimentary layers,and a coupling interaction between the basin and the mountains.The findings are consistent with similar studies,showing that near-fault sedimentary basins significantly focus and amplify strong ground motion,and the soil’s nonlinear behavior in the basin influences ground motion to varying extents at different distances from the fault.The mountainous topography impacts the basin’s response to ground motion,leading to barrier effects.This research provides a scientific foundation for seismic zoning,urban planning,and seismic design in nearfault mountain basin regions.展开更多
Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulati...Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulation method consisting of hydrodynamic and structural calculations has been used to evaluate a catamaran pontoon’s motion and structural integrity.Four different space sizes are set for the pontoon system:5 m,5.5 m,6 m,and 6.5 m.The frequency domain shows that the pontoon space affects the RAO in wave periods ranging from 3 s to 5 s.At wave periods of 3 s,4 s,and 5 s,the pontoon space significantly affects the maximum motion and chain tension parameter values,which are evaluated via time domain simulation.The critical stress of the pontoon is shown at a wave period of 5 s for 5 m and 5.5 m of pontoon space,which shows that the stress can reach 248 MPa.展开更多
This study investigates the effect of nacelle motions on the rotor performance and drivetrain dynamics of floating offshore wind turbines(FOWTs)through fully coupled aero-hydro-elastic-servo-mooring simulations.Using ...This study investigates the effect of nacelle motions on the rotor performance and drivetrain dynamics of floating offshore wind turbines(FOWTs)through fully coupled aero-hydro-elastic-servo-mooring simulations.Using the National Renewable Energy Laboratory 5 MW monopile-supported offshore wind turbine and the OC4 DeepCwind semisubmersible wind turbine as case studies,the research addresses the complex dynamic responses resulting from the interaction among wind,waves,and turbine structures.Detailed multi-body dynamics models of wind turbines,including drivetrain components,are created within the SIMPACK framework.Meanwhile,the mooring system is modeled using a lumped-mass method.Various operational conditions are simulated through five wind-wave load cases.Results demonstrate that nacelle motions significantly influence rotor speed,thrust,torque,and power output,as well as the dynamic loads on drivetrain components.These findings highlight the need for advanced simulation techniques for the design and optimization of FOWTs to ensure reliable performance and longevity.展开更多
The finite-difference method(FDM)is an essential tool in exploration geophysics,particularly for simulating wave propagation in fluid-solid coupled media.Despite its widespread use,FDM faces significant challenges tha...The finite-difference method(FDM)is an essential tool in exploration geophysics,particularly for simulating wave propagation in fluid-solid coupled media.Despite its widespread use,FDM faces significant challenges that affect its accuracy and efficiency.Firstly,the implicit handling of fluid-solid boundary conditions through parameter averaging strategy often results in low simulation accuracy.Secondly,surface topography can introduce staircase diffraction noise when grid spacing is large.To address these issues,this paper presents a novel approach.We derive an implicit expression for fluidsolid boundary conditions based on average medium theory,translating explicit boundary conditions into model parameter modification.This enables implicit handling of fluid-solid boundaries by modifying the parameters near the boundary.Furthermore,to mitigate staircase diffraction noise,we employ multiple interface discretization based on the superposition method.This effectively suppresses staircase diffraction noise without requiring grid refinement.The efficacy of our method in accurately modeling wave propagation phenomena in fluid-solid coupled media is demonstrated by numerical examples.Results align well with those obtained using the spectral element method(SEM),with significant reduction in staircase diffraction noise.展开更多
The global rise in energy demand, particularly in remote and sparsely populated regions, necessitates innovative and cost-effective electrical distribution solutions. Traditional Rural Electrification (RE) methods, li...The global rise in energy demand, particularly in remote and sparsely populated regions, necessitates innovative and cost-effective electrical distribution solutions. Traditional Rural Electrification (RE) methods, like Conventional Rural Electrification (CRE), have proven economically unfeasible in such areas due to high infrastructure costs and low electricity demand. Consequently, Unconventional Rural Electrification (URE) technologies, such as Capacitor Coupled Substations (CCS), are gaining attention as viable alternatives. This study presents the design and simulation of an 80 kW CCS system, which taps power directly from a 132 kV transmission line to supply low-voltage consumers. The critical components of the CCS, the capacitors are calculated, then a MATLAB/Simulink model with the attained results is executed. Mathematical representation and state-space representation for maintaining the desired tapped voltage area also developed. The research further explores the feasibility and operational performance of this CCS configuration, aiming to address the challenges of rural electrification by offering a sustainable and scalable solution. The results show that the desired value of the tapped voltage can be achieved at any level of High Voltage (HV) with the selection of capacitors that are correctly rated. With an adequately designed control strategy, the research also shows that tapped voltage can be attained under both steady-state and dynamic loads. By leveraging CCS technology, the study demonstrates the potential for delivering reliable electricity to underserved areas, highlighting the system’s practicality and effectiveness in overcoming the limitations of conventional distribution methods.展开更多
In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusio...In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusion mobility database, which can accurately predict the phase equilibrium, solute diffusion coefficients, specific heat capacity and latent heat release in the whole system. The results show that these parameters are not constants and their values depend on local concentration and temperature. Quantitative simulation of solidification in multicomponent alloys is almost impossible without such parameters available. In this model, the interfacial region is assumed to be a mixture of solid and liquid with the same chemical potentials, but with different composition. The anti-trapping current is also considered in the model. And this model was successfully applied to industrial A1-Cu-Mg alloy for the free equiaxed dendrite solidification process.展开更多
Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagati...Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagation behavior.To address the unclear mechanisms governing fracture penetration across coal-gangue interfaces,this study employs the Continuum-Discontinuum Element Method(CDEM)to simulate and analyze the vertical propagation of hydraulic fractures initiating within coal seams,based on geomechanical parameters derived from the deep Benxi Formation coal seams in the southeastern Ordos Basin.The investigation systematically examines the influence of geological and operational parameters on cross-interfacial fracture growth.Results demonstrate that vertical stress difference,elastic modulus contrast between coal and gangue layers,interfacial stress differential,and interfacial cohesion at coal-gangue interfaces are critical factors governing hydraulic fracture penetration through these interfaces.High vertical stress differences(>3 MPa)inhibit interfacial dilation,promoting predominant crosslayer fracture propagation.Reduced interfacial stress contrasts and enhanced interfacial cohesion facilitate fracture penetration across interfaces.Furthermore,smaller elastic modulus contrasts between coal and gangue correlate with increased interfacial aperture.Finally,lower injection rates effectively suppress vertical fracture propagation in deep coal reservoirs.This study elucidates the characteristics and mechanisms governing cross-layer fracture propagation in coal–rock composites with interbedded partings,and delineates the dynamic evolution laws and dominant controlling factors involved.Thefindings provide critical theoretical insights for the optimization of fracture design and the efficient development of deep coalbed methane reservoirs.展开更多
The coupling between heat and pressure is the kernel of inertia friction welding(IFW)and is still not fully understood.A novel 3D fully coupled finite element model based on a plastic friction pair was developed to si...The coupling between heat and pressure is the kernel of inertia friction welding(IFW)and is still not fully understood.A novel 3D fully coupled finite element model based on a plastic friction pair was developed to simulate the IFW process of a Ni-based superalloy and reveal the omnidirectional thermo-mechanical coupling mechanism of the friction interface.The numerical model successfully simulated the deceleration,deformation processes,and peak torsional moments in IFW and captured the evolution of temperature,contact pressure,and stress.The simulated results were validated through measured thermal history,optical macrography,and axial shortening.The results indicated that interfacial friction heat was the primary heat source,and plastic deformation energy only accounted for 4%of the total.The increase in initial rotational speed and friction pressure elevated the peak temperature,reaching a maximum of 1525.5K at an initial rotational speed of 2000 r/min and friction pressure of 400 MPa.The interface heat generation could form an axial temperature gradient exceeding 320K/mm.The radial inhomogeneities of heat generation and temperature were manifested in a concentric ring distribution with maximum heat flux and temperature ranging from 2/5 to 2/3 radius.The radial inhomogeneities were caused by increasing linear velocity along the radius and an opposite distribution of contact pressure,which could reach 1.7 times the set pressure at the center.The circumferential inhomogeneity of thermomechanical distribution during rotary friction welding was revealed for the first time,benefiting from the 3D model.The deflection and transformation of distribution in contact pressure and Mises stress were indicators of plastic deformation and transition of quasi-steady state welding.The critical Mises stress was 0.5 times the friction pressure in this study.The presented modeling provides a reliable insight into the thermo-mechanical coupling mechanism of IFW and lays a solid foundation for predicting the microstructures and mechanical properties of inertia friction welded joints.展开更多
The utilization of multi-field coupling simulation methods has become a pivotal approach for the investigation of intricate fracture behavior and interaction mechanisms of rock masses in deep strata.The high temperatu...The utilization of multi-field coupling simulation methods has become a pivotal approach for the investigation of intricate fracture behavior and interaction mechanisms of rock masses in deep strata.The high temperatures,pressures and complex geological environments of deep strata frequently result in the coupling of multiple physical fields,including mechanical,thermal and hydraulic fields,during the fracturing of rocks.This review initially presents an overview of the coupling mechanisms of these physical fields,thereby elucidating the interaction processes ofmechanical,thermal,and hydraulic fields within rockmasses.Secondly,an in-depth analysis ofmulti-field coupling is conducted from both spatial and temporal perspectives,with the introduction of simulation methods for a range of scales.It emphasizes cross-scale coupling methodologies for the transfer of rock properties and physical field data,including homogenization techniques,nested coupling strategies and data-driven approaches.To address the discontinuous characteristics of the rock fracture process,the review provides a detailed explanation of continuousdiscontinuous couplingmethods,to elucidate the evolution of rock fracturing and deformationmore comprehensively.In conclusion,the review presents a summary of the principal points,challenges and future directions of multi-field coupling simulation research.It also puts forward the potential of integrating intelligent algorithms with multi-scale simulation techniques to enhance the accuracy and efficiency of multi-field coupling simulations.This offers novel insights into multi-field coupling simulation analysis in deep rock masses.展开更多
The terrestrial hydrological process is an essential but weak link in global/regional climate models. In this paper, the development status, research hotspots and trends in coupled atmosphere-hydrology simulations are...The terrestrial hydrological process is an essential but weak link in global/regional climate models. In this paper, the development status, research hotspots and trends in coupled atmosphere-hydrology simulations are identified through a bibliometric analysis, and the challenges and opportunities in this field are reviewed and summarized. Most climate models adopt the one-dimensional (vertical) land surface parameterization, which does not include a detailed description of basin-scale hydrological processes, particularly the effects of human activities on the underlying surfaces. To understand the interaction mechanism between hydrological processes and climate change, a large number of studies focused on the climate feedback effects of hydrological processes at different spatio-temporal scales, mainly through the coupling of hydrological and climate models. The improvement of the parameterization of hydrological process and the development of large-scale hydrological model in land surface process model lay a foundation for terrestrial hydrological-climate coupling simulation, based on which, the study of terrestrial hydrological-climate coupling is evolving from the traditional unidirectional coupling research to the two-way coupling study of "climate-hydrology" feedback. However, studies of fully coupled atmosphere-hydrology simulations (also called atmosphere-hydrology two-way coupling) are far from mature. The main challenges associated with these studies are: improving the potential mismatch in hydrological models and climate models; improving the stability of coupled systems; developing an effective scale conversion scheme; perfecting the parameterization scheme; evaluating parameter uncertainties; developing effective methodology for model parameter transplanting; and improving the applicability of models and high/super-resolution simulation. Solving these problems and improving simulation accuracy are directions for future hydro-climate coupling simulation research.展开更多
Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the...Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.展开更多
A coupled supersonic inlet-fan Navier–Stokes simulation method was developed by using COMSOL-CFD code. The flow turning, pressure rise and loss effects across blade rows of the fan and the inlet-fan interactions were...A coupled supersonic inlet-fan Navier–Stokes simulation method was developed by using COMSOL-CFD code. The flow turning, pressure rise and loss effects across blade rows of the fan and the inlet-fan interactions were taken into account as source terms of the governing equations without a blade geometry by a body force model. In this model, viscous effects in blade passages can also be calculated directly, which include the exchange of momentum between fluids and detailed viscous flow close to walls. NASA Rotor 37 compressor test rig was used to validate the ability of the body force model to estimate the real performance of blade rows. Calculated pressure ratio characteristics and the distribution of the total pressure, total temperature, and swirl angle in the span direction agreed well with experimental and numerical data. It is shown that the body force model is a promising approach for predicting the flow field of the turbomachinery. Then, coupled axisymmetric mixed compression supersonic inlet-fan simulations were conducted at Mach number 2.8 operating conditions. The analysis includes coupled steady-state performance, and effects of the fan on the inlet. The results indicate that the coupled simulation method is capable of simulating behavior of the supersonic inlet-fan system.展开更多
A new hybrid coupled model(HCM) is presented in this study, which consists of an intermediate tropical Pacific Ocean model and a global atmospheric general circulation model. The ocean component is the intermediate oc...A new hybrid coupled model(HCM) is presented in this study, which consists of an intermediate tropical Pacific Ocean model and a global atmospheric general circulation model. The ocean component is the intermediate ocean model(IOM)of the intermediate coupled model(ICM) used at the Institute of Oceanology, Chinese Academy of Sciences(IOCAS). The atmospheric component is ECHAM5, the fifth version of the Max Planck Institute for Meteorology atmospheric general circulation model. The HCM integrates its atmospheric and oceanic components by using an anomaly coupling strategy. A100-year simulation has been made with the HCM and its simulation skills are evaluated, including the interannual variability of SST over the tropical Pacific and the ENSO-related responses of the global atmosphere. The model shows irregular occurrence of ENSO events with a spectral range between two and five years. The amplitude and lifetime of ENSO events and the annual phase-locking of SST anomalies are also reproduced realistically. Despite the slightly stronger variance of SST anomalies over the central Pacific than observed in the HCM, the patterns of atmospheric anomalies related to ENSO,such as sea level pressure, temperature and precipitation, are in broad agreement with observations. Therefore, this model can not only simulate the ENSO variability, but also reproduce the global atmospheric variability associated with ENSO, thereby providing a useful modeling tool for ENSO studies. Further model applications of ENSO modulations by ocean–atmosphere processes, and of ENSO-related climate prediction, are also discussed.展开更多
Reasonably accurate predictions of wave heights, current and elevations during storm events are vital information for marine operations and design of offshore and coastal structures in the surrounding seas of Korea Pe...Reasonably accurate predictions of wave heights, current and elevations during storm events are vital information for marine operations and design of offshore and coastal structures in the surrounding seas of Korea Peninsula. Ocean circulation and wind-wave models have traditionally been run separately, but recent researches have identified potentially important interactions between current and wave motions. The coupled tide-surge and the WAM wave models at the atmospheric boundary layer and bottom boundary layer around the Korea Peninsula are applied for the Typhoon Maemi （0314） event. Communication between the models is aehievod using MPI. Results are compared with coastal tide gauges and moored wave buoys and comparisons are also made between wave computations from the coupled model and the independent third generation wave models. Results suggest that applying the fide-surge-coupled model can be an effective means of obtaining wave and storm surge predictions simultaneously.展开更多
A mathematical model for coupled multiphase fluid flow and sedi- mentation deformation is developed based on fluid-solid interaction mechanism.A finite difference-finite element numerical approach is presented.The res...A mathematical model for coupled multiphase fluid flow and sedi- mentation deformation is developed based on fluid-solid interaction mechanism.A finite difference-finite element numerical approach is presented.The results of an example show that the fluid-solid coupled effect has great influence on multiphase fluid flow and reservoir recovery performances,and the coupled model has practical significance for oilfield development.展开更多
To predict three-dimensional temperature distribution of molten aluminum and its influencing factors inside an industrial aluminum holding furnace,a fluid-solid coupled method was presented.The fluid-solid coupled mat...To predict three-dimensional temperature distribution of molten aluminum and its influencing factors inside an industrial aluminum holding furnace,a fluid-solid coupled method was presented.The fluid-solid coupled mathematics models of aluminum holding furnace in the premixed combustion processing were established based on mass conservation,moment conservation,momentum conservation,energy conservation and chemistry species conservation.Computational results agree well with the test data of the typical condition.The maximum combustion temperature is 1 850 K.The average temperature of the molten aluminum is 1 158 K,and the maximum temperature difference is about 240 K.The average temperature increases 0.3 ℃ while the temperature of combustion air increases 1 ℃.The optimal excess air ratio is 1.25-1.30.展开更多
Simulating the coupled motions of multiple bodies in the time domain is a complex problem because of the strong hydrodynamic interactions and coupled effect of various mechanical connectors. In this study, we investig...Simulating the coupled motions of multiple bodies in the time domain is a complex problem because of the strong hydrodynamic interactions and coupled effect of various mechanical connectors. In this study, we investigate the hydrodynamic responses of three barges moored side-by-side in a floatover operation in the frequency and time domains. In the frequency domain, the damping lid method is adopted to improve the overestimated hydrodynamic coefficients calculated from conventional potential flow theory. A time-domain computing program based on potential flow theory and impulse theory is compiled for analyses that consider multibody hydrodynamic interactions and mechanical effects from lines and fenders. Correspondingly, an experiment is carried out for comparison with the numerical results. All statistics, time series, and power density spectra from decay and irregular wave tests are in a fairly good agreement.展开更多
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金supported by the National Natural Science Foundation of China(Grant Nos.22193032 and 32401033)the Research Fund of Wenzhou Institute,Chinese Academy of Sciences(Grant Nos.WIUCASQD2020009,WIUCASQD2023005,XSZD2024004,2021HZSY0061,and WIUCASICTP2022)。
文摘The F_(1)-ATPase and V_(1)-ATPase are rotary biomotors.Alignment of their amino acid sequences,which originate from bovine heart mitochondria(1BMF)and Enterococcus hirae(3VR6),respectively,demonstrates that the segment forming the ATP catalytic pocket is highly conserved.Single-molecule experiments,however,have revealed subtle differences in efficiency between the F_(1) and V_(1) motors.Here,we perform both atomistic and coarse-grained molecular dynamics simulations to investigate the mechanochemical coupling and coordination in F_(1) and V_(1) ATPase.Our results show that the correlation between conformational changes in F_(1) is stronger than that in V_(1),indicating that the mechanochemical coupling in F_(1) is tighter than in V_(1).Moreover,the unidirectional rotation of F_(1) is more processive than that of V_(1),which accounts for the higher efficiency observed in F_(1) and explains the occasional backward steps detected in single-molecule experiments on V_(1).
基金National Natural Science Foundation of China under Grant Nos.U2139208 and 52278516Key Laboratory of Earthquake Engineering and Engineering Vibration,China Earthquake Administration under Grant No.2024D15Key Laboratory of Soft Soil Characteristic and Engineering Environment,Tianjin Chengjian University under Grant No.2022SCEEKL003。
文摘This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SEM),which is used to simulate low-frequency ground motion(f<1 Hz)by incorporating an innovative efficient discontinuous Galerkin(DG)method for grid division to accurately model basin sedimentary layers at reduced costs.It also introduces a comprehensive hybrid source model for high-frequency random scattering and a nonlinear analysis module for basin sedimentary layers.Deterministic outcomes are combined with modified three-dimensional stochastic finite fault method(3D-EXSIM)simulations of high-frequency ground motion(f>1 Hz).A fourth-order Butterworth filter with zero phase shift is employed for time-domain filtering of low-and high-frequency time series at a crossover frequency of 1 Hz,merging the low and high-frequency ground motions into a broadband time series.Taking an Ms 6.8 Luding earthquake,as an example,this hybrid method was used for a rapid and efficient simulation analysis of broadband ground motion in the region.The accuracy and efficiency of this hybrid method were verified through comparisons with actually observed station data and empirical attenuation curves.Deterministic method simulation results revealed the effects of mountainous topography,basin effects,nonlinear effects within the basin’s sedimentary layers,and a coupling interaction between the basin and the mountains.The findings are consistent with similar studies,showing that near-fault sedimentary basins significantly focus and amplify strong ground motion,and the soil’s nonlinear behavior in the basin influences ground motion to varying extents at different distances from the fault.The mountainous topography impacts the basin’s response to ground motion,leading to barrier effects.This research provides a scientific foundation for seismic zoning,urban planning,and seismic design in nearfault mountain basin regions.
基金financially supported by the Riset Pengembangan dan Penerapan(RPP),Diponegoro University 2023 research scheme with contract number 609-18/UN7.D2/PP/VIII/2023.
文摘Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulation method consisting of hydrodynamic and structural calculations has been used to evaluate a catamaran pontoon’s motion and structural integrity.Four different space sizes are set for the pontoon system:5 m,5.5 m,6 m,and 6.5 m.The frequency domain shows that the pontoon space affects the RAO in wave periods ranging from 3 s to 5 s.At wave periods of 3 s,4 s,and 5 s,the pontoon space significantly affects the maximum motion and chain tension parameter values,which are evaluated via time domain simulation.The critical stress of the pontoon is shown at a wave period of 5 s for 5 m and 5.5 m of pontoon space,which shows that the stress can reach 248 MPa.
基金Supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission of China(Grant No.:KJQN202301105,KJQN202101550)Scientific Research Fund of Chongqing University of Technology(grant No.2021ZDZ015)National Nature Science Foundation of China(No.:52205052).
文摘This study investigates the effect of nacelle motions on the rotor performance and drivetrain dynamics of floating offshore wind turbines(FOWTs)through fully coupled aero-hydro-elastic-servo-mooring simulations.Using the National Renewable Energy Laboratory 5 MW monopile-supported offshore wind turbine and the OC4 DeepCwind semisubmersible wind turbine as case studies,the research addresses the complex dynamic responses resulting from the interaction among wind,waves,and turbine structures.Detailed multi-body dynamics models of wind turbines,including drivetrain components,are created within the SIMPACK framework.Meanwhile,the mooring system is modeled using a lumped-mass method.Various operational conditions are simulated through five wind-wave load cases.Results demonstrate that nacelle motions significantly influence rotor speed,thrust,torque,and power output,as well as the dynamic loads on drivetrain components.These findings highlight the need for advanced simulation techniques for the design and optimization of FOWTs to ensure reliable performance and longevity.
基金supported by the National Natural Science Foundation of China(Nos.42404134,U24B2031,42174160)the China Postdoctoral Science Foundation(No.2024M753204)the National Key R&D Program of China(Nos.2021YFA0716901,2022YFB3904601)。
文摘The finite-difference method(FDM)is an essential tool in exploration geophysics,particularly for simulating wave propagation in fluid-solid coupled media.Despite its widespread use,FDM faces significant challenges that affect its accuracy and efficiency.Firstly,the implicit handling of fluid-solid boundary conditions through parameter averaging strategy often results in low simulation accuracy.Secondly,surface topography can introduce staircase diffraction noise when grid spacing is large.To address these issues,this paper presents a novel approach.We derive an implicit expression for fluidsolid boundary conditions based on average medium theory,translating explicit boundary conditions into model parameter modification.This enables implicit handling of fluid-solid boundaries by modifying the parameters near the boundary.Furthermore,to mitigate staircase diffraction noise,we employ multiple interface discretization based on the superposition method.This effectively suppresses staircase diffraction noise without requiring grid refinement.The efficacy of our method in accurately modeling wave propagation phenomena in fluid-solid coupled media is demonstrated by numerical examples.Results align well with those obtained using the spectral element method(SEM),with significant reduction in staircase diffraction noise.
文摘The global rise in energy demand, particularly in remote and sparsely populated regions, necessitates innovative and cost-effective electrical distribution solutions. Traditional Rural Electrification (RE) methods, like Conventional Rural Electrification (CRE), have proven economically unfeasible in such areas due to high infrastructure costs and low electricity demand. Consequently, Unconventional Rural Electrification (URE) technologies, such as Capacitor Coupled Substations (CCS), are gaining attention as viable alternatives. This study presents the design and simulation of an 80 kW CCS system, which taps power directly from a 132 kV transmission line to supply low-voltage consumers. The critical components of the CCS, the capacitors are calculated, then a MATLAB/Simulink model with the attained results is executed. Mathematical representation and state-space representation for maintaining the desired tapped voltage area also developed. The research further explores the feasibility and operational performance of this CCS configuration, aiming to address the challenges of rural electrification by offering a sustainable and scalable solution. The results show that the desired value of the tapped voltage can be achieved at any level of High Voltage (HV) with the selection of capacitors that are correctly rated. With an adequately designed control strategy, the research also shows that tapped voltage can be attained under both steady-state and dynamic loads. By leveraging CCS technology, the study demonstrates the potential for delivering reliable electricity to underserved areas, highlighting the system’s practicality and effectiveness in overcoming the limitations of conventional distribution methods.
基金Project(2011CB606306) supported by the National Basic Research Program of ChinaProject(51101014) supported by the National Natural Science Foundation of China
文摘In order to quantitively model the real solidification process of industrial multicomponent alloys, a non-isothermal phase field model was studied for multicomponent alloy fully coupled with thermodynamic and diffusion mobility database, which can accurately predict the phase equilibrium, solute diffusion coefficients, specific heat capacity and latent heat release in the whole system. The results show that these parameters are not constants and their values depend on local concentration and temperature. Quantitative simulation of solidification in multicomponent alloys is almost impossible without such parameters available. In this model, the interfacial region is assumed to be a mixture of solid and liquid with the same chemical potentials, but with different composition. The anti-trapping current is also considered in the model. And this model was successfully applied to industrial A1-Cu-Mg alloy for the free equiaxed dendrite solidification process.
文摘Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagation behavior.To address the unclear mechanisms governing fracture penetration across coal-gangue interfaces,this study employs the Continuum-Discontinuum Element Method(CDEM)to simulate and analyze the vertical propagation of hydraulic fractures initiating within coal seams,based on geomechanical parameters derived from the deep Benxi Formation coal seams in the southeastern Ordos Basin.The investigation systematically examines the influence of geological and operational parameters on cross-interfacial fracture growth.Results demonstrate that vertical stress difference,elastic modulus contrast between coal and gangue layers,interfacial stress differential,and interfacial cohesion at coal-gangue interfaces are critical factors governing hydraulic fracture penetration through these interfaces.High vertical stress differences(>3 MPa)inhibit interfacial dilation,promoting predominant crosslayer fracture propagation.Reduced interfacial stress contrasts and enhanced interfacial cohesion facilitate fracture penetration across interfaces.Furthermore,smaller elastic modulus contrasts between coal and gangue correlate with increased interfacial aperture.Finally,lower injection rates effectively suppress vertical fracture propagation in deep coal reservoirs.This study elucidates the characteristics and mechanisms governing cross-layer fracture propagation in coal–rock composites with interbedded partings,and delineates the dynamic evolution laws and dominant controlling factors involved.Thefindings provide critical theoretical insights for the optimization of fracture design and the efficient development of deep coalbed methane reservoirs.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3404904)。
文摘The coupling between heat and pressure is the kernel of inertia friction welding(IFW)and is still not fully understood.A novel 3D fully coupled finite element model based on a plastic friction pair was developed to simulate the IFW process of a Ni-based superalloy and reveal the omnidirectional thermo-mechanical coupling mechanism of the friction interface.The numerical model successfully simulated the deceleration,deformation processes,and peak torsional moments in IFW and captured the evolution of temperature,contact pressure,and stress.The simulated results were validated through measured thermal history,optical macrography,and axial shortening.The results indicated that interfacial friction heat was the primary heat source,and plastic deformation energy only accounted for 4%of the total.The increase in initial rotational speed and friction pressure elevated the peak temperature,reaching a maximum of 1525.5K at an initial rotational speed of 2000 r/min and friction pressure of 400 MPa.The interface heat generation could form an axial temperature gradient exceeding 320K/mm.The radial inhomogeneities of heat generation and temperature were manifested in a concentric ring distribution with maximum heat flux and temperature ranging from 2/5 to 2/3 radius.The radial inhomogeneities were caused by increasing linear velocity along the radius and an opposite distribution of contact pressure,which could reach 1.7 times the set pressure at the center.The circumferential inhomogeneity of thermomechanical distribution during rotary friction welding was revealed for the first time,benefiting from the 3D model.The deflection and transformation of distribution in contact pressure and Mises stress were indicators of plastic deformation and transition of quasi-steady state welding.The critical Mises stress was 0.5 times the friction pressure in this study.The presented modeling provides a reliable insight into the thermo-mechanical coupling mechanism of IFW and lays a solid foundation for predicting the microstructures and mechanical properties of inertia friction welded joints.
基金supported by the National Natural Science Foundation of China(Grant Nos.42477185,41602308)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY20E080005)the Postgraduate Course Construction Project of Zhejiang University of Science and Technology(Grant No.2021yjskj05).
文摘The utilization of multi-field coupling simulation methods has become a pivotal approach for the investigation of intricate fracture behavior and interaction mechanisms of rock masses in deep strata.The high temperatures,pressures and complex geological environments of deep strata frequently result in the coupling of multiple physical fields,including mechanical,thermal and hydraulic fields,during the fracturing of rocks.This review initially presents an overview of the coupling mechanisms of these physical fields,thereby elucidating the interaction processes ofmechanical,thermal,and hydraulic fields within rockmasses.Secondly,an in-depth analysis ofmulti-field coupling is conducted from both spatial and temporal perspectives,with the introduction of simulation methods for a range of scales.It emphasizes cross-scale coupling methodologies for the transfer of rock properties and physical field data,including homogenization techniques,nested coupling strategies and data-driven approaches.To address the discontinuous characteristics of the rock fracture process,the review provides a detailed explanation of continuousdiscontinuous couplingmethods,to elucidate the evolution of rock fracturing and deformationmore comprehensively.In conclusion,the review presents a summary of the principal points,challenges and future directions of multi-field coupling simulation research.It also puts forward the potential of integrating intelligent algorithms with multi-scale simulation techniques to enhance the accuracy and efficiency of multi-field coupling simulations.This offers novel insights into multi-field coupling simulation analysis in deep rock masses.
基金National Key R&D Program of China,No.2017YFA0603702National Natural Science Foundation of China,No.41571019,No.41701023,No.41571028China Postdoctoral Science Foundation,No.2017M610867
文摘The terrestrial hydrological process is an essential but weak link in global/regional climate models. In this paper, the development status, research hotspots and trends in coupled atmosphere-hydrology simulations are identified through a bibliometric analysis, and the challenges and opportunities in this field are reviewed and summarized. Most climate models adopt the one-dimensional (vertical) land surface parameterization, which does not include a detailed description of basin-scale hydrological processes, particularly the effects of human activities on the underlying surfaces. To understand the interaction mechanism between hydrological processes and climate change, a large number of studies focused on the climate feedback effects of hydrological processes at different spatio-temporal scales, mainly through the coupling of hydrological and climate models. The improvement of the parameterization of hydrological process and the development of large-scale hydrological model in land surface process model lay a foundation for terrestrial hydrological-climate coupling simulation, based on which, the study of terrestrial hydrological-climate coupling is evolving from the traditional unidirectional coupling research to the two-way coupling study of "climate-hydrology" feedback. However, studies of fully coupled atmosphere-hydrology simulations (also called atmosphere-hydrology two-way coupling) are far from mature. The main challenges associated with these studies are: improving the potential mismatch in hydrological models and climate models; improving the stability of coupled systems; developing an effective scale conversion scheme; perfecting the parameterization scheme; evaluating parameter uncertainties; developing effective methodology for model parameter transplanting; and improving the applicability of models and high/super-resolution simulation. Solving these problems and improving simulation accuracy are directions for future hydro-climate coupling simulation research.
基金the National High Technical Reasearch and Development Programme of China （No. 2003AA327140） the National Natural Science Foundation of China （No. 50374081）.
文摘Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.
基金support of National Natural Science Foundation of China (Nos. 51706008 and 51636001)China Postdoctoral Science Foundation (No. 2017M610742)Aeronautics Power Foundation of China (No. 6141B090315)
文摘A coupled supersonic inlet-fan Navier–Stokes simulation method was developed by using COMSOL-CFD code. The flow turning, pressure rise and loss effects across blade rows of the fan and the inlet-fan interactions were taken into account as source terms of the governing equations without a blade geometry by a body force model. In this model, viscous effects in blade passages can also be calculated directly, which include the exchange of momentum between fluids and detailed viscous flow close to walls. NASA Rotor 37 compressor test rig was used to validate the ability of the body force model to estimate the real performance of blade rows. Calculated pressure ratio characteristics and the distribution of the total pressure, total temperature, and swirl angle in the span direction agreed well with experimental and numerical data. It is shown that the body force model is a promising approach for predicting the flow field of the turbomachinery. Then, coupled axisymmetric mixed compression supersonic inlet-fan simulations were conducted at Mach number 2.8 operating conditions. The analysis includes coupled steady-state performance, and effects of the fan on the inlet. The results indicate that the coupled simulation method is capable of simulating behavior of the supersonic inlet-fan system.
基金supported by the National Natural Science Foundation of China (NFSCGrant No. 41706016)+3 种基金the National Programme on Global Change and Air– Sea Interaction (Grant No. GASI-IPOVAI-06)the NFSC [Grant Nos. 41690122(41690120), 41606019 and 41421005]the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA19060102)the NSFC–Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406402)
文摘A new hybrid coupled model(HCM) is presented in this study, which consists of an intermediate tropical Pacific Ocean model and a global atmospheric general circulation model. The ocean component is the intermediate ocean model(IOM)of the intermediate coupled model(ICM) used at the Institute of Oceanology, Chinese Academy of Sciences(IOCAS). The atmospheric component is ECHAM5, the fifth version of the Max Planck Institute for Meteorology atmospheric general circulation model. The HCM integrates its atmospheric and oceanic components by using an anomaly coupling strategy. A100-year simulation has been made with the HCM and its simulation skills are evaluated, including the interannual variability of SST over the tropical Pacific and the ENSO-related responses of the global atmosphere. The model shows irregular occurrence of ENSO events with a spectral range between two and five years. The amplitude and lifetime of ENSO events and the annual phase-locking of SST anomalies are also reproduced realistically. Despite the slightly stronger variance of SST anomalies over the central Pacific than observed in the HCM, the patterns of atmospheric anomalies related to ENSO,such as sea level pressure, temperature and precipitation, are in broad agreement with observations. Therefore, this model can not only simulate the ENSO variability, but also reproduce the global atmospheric variability associated with ENSO, thereby providing a useful modeling tool for ENSO studies. Further model applications of ENSO modulations by ocean–atmosphere processes, and of ENSO-related climate prediction, are also discussed.
文摘Reasonably accurate predictions of wave heights, current and elevations during storm events are vital information for marine operations and design of offshore and coastal structures in the surrounding seas of Korea Peninsula. Ocean circulation and wind-wave models have traditionally been run separately, but recent researches have identified potentially important interactions between current and wave motions. The coupled tide-surge and the WAM wave models at the atmospheric boundary layer and bottom boundary layer around the Korea Peninsula are applied for the Typhoon Maemi （0314） event. Communication between the models is aehievod using MPI. Results are compared with coastal tide gauges and moored wave buoys and comparisons are also made between wave computations from the coupled model and the independent third generation wave models. Results suggest that applying the fide-surge-coupled model can be an effective means of obtaining wave and storm surge predictions simultaneously.
文摘A mathematical model for coupled multiphase fluid flow and sedi- mentation deformation is developed based on fluid-solid interaction mechanism.A finite difference-finite element numerical approach is presented.The results of an example show that the fluid-solid coupled effect has great influence on multiphase fluid flow and reservoir recovery performances,and the coupled model has practical significance for oilfield development.
基金Project(2006AA03Z523) supported by the National High-Tech Research and Development Program of ChinaProject(08C26224302178) supported by the Innovation Foundation of Central South University,China
文摘To predict three-dimensional temperature distribution of molten aluminum and its influencing factors inside an industrial aluminum holding furnace,a fluid-solid coupled method was presented.The fluid-solid coupled mathematics models of aluminum holding furnace in the premixed combustion processing were established based on mass conservation,moment conservation,momentum conservation,energy conservation and chemistry species conservation.Computational results agree well with the test data of the typical condition.The maximum combustion temperature is 1 850 K.The average temperature of the molten aluminum is 1 158 K,and the maximum temperature difference is about 240 K.The average temperature increases 0.3 ℃ while the temperature of combustion air increases 1 ℃.The optimal excess air ratio is 1.25-1.30.
基金financially supported by Lloyd’s Register Foundation(LRF),a UK-registered charity and sole shareholder of Lloyd’s Register Group Ltd.the Youth Innovation Fund of State Key Laboratory of Ocean Engineering(Grant No.GKZD010059-21)
文摘Simulating the coupled motions of multiple bodies in the time domain is a complex problem because of the strong hydrodynamic interactions and coupled effect of various mechanical connectors. In this study, we investigate the hydrodynamic responses of three barges moored side-by-side in a floatover operation in the frequency and time domains. In the frequency domain, the damping lid method is adopted to improve the overestimated hydrodynamic coefficients calculated from conventional potential flow theory. A time-domain computing program based on potential flow theory and impulse theory is compiled for analyses that consider multibody hydrodynamic interactions and mechanical effects from lines and fenders. Correspondingly, an experiment is carried out for comparison with the numerical results. All statistics, time series, and power density spectra from decay and irregular wave tests are in a fairly good agreement.
