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
High performance electromechanical equipment is widely used in various fields, such as national defense, industry and so on [ 1]. In addition, the technical level of high performance electromechanical equipment is the...High performance electromechanical equipment is widely used in various fields, such as national defense, industry and so on [ 1]. In addition, the technical level of high performance electromechanical equipment is the embodiment of the national level of science and technology.展开更多
Monitoring various internal parameters plays a core role in ensuring the safety of lithium-ion batteries in power supply applications.It also influences the sustainability effect and online state of charge prediction....Monitoring various internal parameters plays a core role in ensuring the safety of lithium-ion batteries in power supply applications.It also influences the sustainability effect and online state of charge prediction.An improved multiple feature-electrochemical thermal coupling modeling method is proposed considering low-temperature performance degradation for the complete characteristic expression of multi-dimensional information.This is to obtain the parameter influence mechanism with a multi-variable coupling relationship.An optimized decoupled deviation strategy is constructed for accurate state of charge prediction with real-time correction of time-varying current and temperature effects.The innovative decoupling method is combined with the functional relationships of state of charge and open-circuit voltage to capture energy management ef-fectively.Then,an adaptive equivalent-prediction model is constructed using the state-space equation and iterative feedback correction,making the proposed model adaptive to fractional calculation.The maximum state of charge estimation errors of the proposed method are 4.57% and 0.223% under the Beijing bus dynamic stress test and dynamic stress test conditions,respectively.The improved multiple feature-electrochemical thermal coupling modeling realizes the effective correction of the current and temperature variations with noise influencing coefficient,and provides an efficient state of charge prediction method adaptive to complex conditions.展开更多
The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and di...The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and discrete element method(DEM)was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack.The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road.Finally,an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress,vertical shear stress,and vertical compressive stress.The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface,while the longitudinal development of TD crack has minimal impact.This phenomenon may result in more severe fatigue failure on the middle surface.With the vertical and longitudinal development of TD crack,the vertical shear stress and compressive stress show obvious"two-stage"characteristics.When the crack's vertical length reaches 40 mm,there is a sharp increase in stress on the upper surface.As the crack continues to propagate vertically,the growth of stress on the upper surface becomes negligible,while the stress in the middle and lower layers increased significantly.Conversely,for longitudinal development of TD crack,any changes in stress are insignificant when their length is less than 180 mm;however,as they continue to develop longitudinally beyond this threshold,there is a sharp increase in stress levels.These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.展开更多
The utilization of coalbed methane(CBM)cannot only alleviate the energy crisis,but also reduce greenhouse gas emissions.Gas injection is an effective method to enhance CBM recovery.Compared to single-gas injection,the...The utilization of coalbed methane(CBM)cannot only alleviate the energy crisis,but also reduce greenhouse gas emissions.Gas injection is an effective method to enhance CBM recovery.Compared to single-gas injection,the injection of CO_(2)/N_(2) mixtures can balance the sharp decline in permeability caused by pure CO_(2) and the premature breakthrough by pure N_(2).In this study,a more comprehensive thermo-hydro-mechanical(THM)coupled mathematical model was developed,incorporating processes such as ternary gas non-isothermal adsorption,gas dissolution in water,gas-water two-phase flow,energy exchange,and coal deformation.After experimental validation,the model was applied to simulate the entire process of gas mixtures for enhanced CBM recovery(GM-ECBM).Results indicate that the permeability near the production well(Pw)initially decreases due to increased effective stress,then increases as a result of CH_(4) desorption.Near the injection well(Iw),the permeability first increases due to reduced effective stress and later stabilizes under the combined effects of effective stress and CO_(2)/N_(2) adsorption.The initial CH_(4) pressure and coal seam permeability have the most significant impact on CH_(4) production,while the coal seam permeability and temperature significantly affect CO_(2)/N_(2) injection.As the coal seam permeability increases,the optimal CO_(2)/N_(2) ratio also increases accordingly.These findings provide important theoretical guidance for improving GM-ECBM efficiency in coal seams with varying permeabilities.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
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
Oxidative coupling of methane(OCM)is a catalytic partial oxidation process that directly converts methane into C_(2) products.For this high temperature reaction,understanding the radical behavior through experimental ...Oxidative coupling of methane(OCM)is a catalytic partial oxidation process that directly converts methane into C_(2) products.For this high temperature reaction,understanding the radical behavior through experimental investigation is important in correlating the catalytic activity and the products.In this work,a spatial resolution online mass spectrometry(MS)system was developed and applied to a Mn-Na_(2)WO_(4)/SiO_(2) catalyzed OCM system.In addition to the residue gas analysis,the system obtained the distribution information of the reactants and products in the reactor.At various setting temperatures,all species online MS signals were collected at different positions,mapping the reaction activity covering parameters including temperature,time and space.The distribution behavior of the catalytic activity,selectivity,and apparent activation energy were kinetically analyzed.Selectivity and additional carbon balance analysis strongly supported the radical coupling model of OCM and indicated that after the catalytic bed layer,there is a significant length in the reactor(>2 mm)filled with radicals.Based on the result,a designed new method by tuning the temperature field in the reactor was found effectively to improve the catalytic activity,especially the C_(2) yield from 702 to 773℃.展开更多
The largely bending bilayer electrode model battery has been widely used to measure the mechanical properties of composite electrode materials.The assumption used in the method that lithium is uniformly distributed in...The largely bending bilayer electrode model battery has been widely used to measure the mechanical properties of composite electrode materials.The assumption used in the method that lithium is uniformly distributed in the active layer lacks quantitative evaluation,and the uniformity of concentration distribution is crucial for accurate in-situ measurements of concentration-related material properties and stress in bilayer electrodes.Therefore,this paper proposes a mechanical-electrochemical coupled model to study the lithium concentration distribution in the active layer during lithiation.This model includes lithium concentration diffusion and active layer deformation.By comparing experimental and simulated curvature evolution of the active layer during lithiation and delithiation,the reliability of this simulation model is verified.We then derive the precise concentration distribution inside the active layer and suggest using relative error to quantitatively evaluate the uniformity of lithium concentration in the active layer.Results show that a low relative error in lithium concentration can be achieved in the middle region of the active layer.Additionally,the effects of different rates and geometric parameters on the lithium concentration distribution in the active layer are discussed.Results indicate that reduced rates,thinner active layers,shorter active layer lengths,and increased spacing between the working and counter electrodes can lead to a more uniform distribution of lithium concentration in the active layer.These insights help improve experimental methods and equipment,promoting uniform distribution of lithium in the active layer and enhancing measurement accuracy.展开更多
The uneven distribution of medical resources has led to increasingly frequent patient mobility;however, the interaction between this phenomenon and the healthcare supply-demand relationship remains underexplored. The ...The uneven distribution of medical resources has led to increasingly frequent patient mobility;however, the interaction between this phenomenon and the healthcare supply-demand relationship remains underexplored. The present study constructed the 2023Cross-City Patient Mobility Network in China using one million patient mobility data records obtained from online healthcare platforms. We applied urban network analysis to uncover mobility patterns and used the coupling coordination degree model to assess healthcare supply-demand relationships before and after patient mobility. Explainable machine learning further revealed the impact of supply-demand coupling on patient mobility. The results indicated the following: Patient mobility followed administrative boundaries, although megacities serve areas beyond provincial borders;The scale of healthcare supply and demand displayed a multi-centric spatial pattern with a general decline from east to west, and these characteristics of demand distribution were further solidified by patient mobility;Cities with low supply-demand coupling and undersupply experienced patient outflows, while cities with high coupling and oversupply attracted them. In turn, patient mobility helped balance healthcare supply and demand, optimising the coupling relationship across cities. Thus, this research not only provides a methodological reference for understanding the interaction between patient mobility and healthcare systems but also offers empirical insights for public health policy.展开更多
In view of the problem that a single modeling method cannot predict the distribution of microfacies, a new idea of coupling modeling method to comprehensively predict the distribution of sedimentary microfacies was pr...In view of the problem that a single modeling method cannot predict the distribution of microfacies, a new idea of coupling modeling method to comprehensively predict the distribution of sedimentary microfacies was proposed, breaking the tradition that different sedimentary microfacies used the same modeling method in the past. Because different sedimentary microfacies have different distribution characteristics and geometric shapes, it is more accurate to select different simulation methods for prediction. In this paper, the coupling modeling method was to establish the distribution of sedimentary microfacies with simple geometry through the point indicating process simulation, and then predict the microfacies with complex spatial distribution through the sequential indicator simulation method. Taking the DC block of Bohai basin as an example, a high-precision reservoir sedimentary microfacies model was established by the above coupling modeling method, and the model verification results showed that the sedimentary microfacies model had a high consistency with the underground. The coupling microfacies modeling method had higher accuracy and reliability than the traditional modeling method, which provided a new idea for the prediction of sedimentary microfacies.展开更多
The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformatio...The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simul- taneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through intro- ducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the cou- pled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural defor- mation movement＇s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment ofdynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.展开更多
Pyrotechnic devices are widely used in the aerospace and defense industries.However,these devices generate high-frequency and high-amplitude shock responses during their use,compromising safe operation of the system.I...Pyrotechnic devices are widely used in the aerospace and defense industries.However,these devices generate high-frequency and high-amplitude shock responses during their use,compromising safe operation of the system.In this paper,the application of a thin-walled circular tube as the energy absorber in pyrotechnic devices is investigated.To accurately predict the shock load and the buffer performance of the thin-walled circular tube,a coupled model connecting the energetic material combustion and finite element simulation is established.The validity of the coupled model is verified by comparing with experiments.Then,the collapse mechanism of the thin-walled circular tube is studied,and the influence of multiple structural parameters on its buffer performance is analyzed.The results show that the thin-walled circular tube effectively reduces the shock overload.The maximum shock overload reduced from 572612g to 11204g in the studied case.The structural parameters of the thin-walled circular tube mainly affect the deformation process and the maximum shock overload.The order of importance of structural parameters to the maximum shock overload is determined,among which the wall thickness has the most significant effect.展开更多
Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation ...Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation of this system. The dynamic model of the heavy-equipment airdrop is based on the Lagrange analytical mechanics, which has all the degrees of freedom and can accurately pinpoint the real-time coordinates and attitude of the carrier with its cargo. Unfavorable conditions accounted in the factors＇ models, including aircraft malfunctions and adverse environments, are established from a man-machine-environment perspective. Subsequently, a virtual simulation system for the safety research of the multi-factor coupling heavy-equipment airdrop is developed through MATLAB/Simulink, C language and Flightgear software. To verify the veracity of the theory, the verification model is built based on dynamic software ADAMS. Finally, the emulation is put to the test with the input of realistic accident variables to ascertain its feasibility and validity of this method.展开更多
Energy storage batteries can smooth the volatility of renewable energy sources.The operating conditions during power grid integration of renewable energy can affect the performance and failure risk of battery energy s...Energy storage batteries can smooth the volatility of renewable energy sources.The operating conditions during power grid integration of renewable energy can affect the performance and failure risk of battery energy storage system(BESS).However,the current modeling of grid-connected BESS is overly simplistic,typically only considering state of charge(SOC)and power constraints.Detailed lithium(Li)-ion battery cell models are computationally intensive and impractical for real-time applications and may not be suitable for power grid operating conditions.Additionally,there is a lack of real-time batteries risk assessment frameworks.To address these issues,in this study,we establish a thermal-electric-performance(TEP)coupling model based on a multitime scale BESS model,incorporating the electrical and thermal characteristics of Li-ion batteries along with their performance degradation to achieve detailed simulation of grid-connected BESS.Additionally,considering the operating characteristics of energy storage batteries and electrical and thermal abuse factors,we developed a battery pack operational riskmodel,which takes into account SOCand charge-discharge rate(Cr),using amodified failure rate to represent the BESS risk.By integrating detailed simulation of energy storage with predictive failure risk analysis,we obtained a detailed model for BESS risk analysis.This model offers a multi-time scale integrated simulation that spans month-level energy storage simulation times,day-level performance degradation,minutescale failure rate,and second-level BESS characteristics.It offers a critical tool for the study of BESS.Finally,the performance and risk of energy storage batteries under three scenarios—microgrid energy storage,wind power smoothing,and power grid failure response—are simulated,achieving a real-time state-dependent operational risk analysis of the BESS.展开更多
Based on the deformation theory of elastic beams, the coupling effect between the coupling displacements of a point on the middle line of beam and large overall motion is presented. The 'coupling matrix library...Based on the deformation theory of elastic beams, the coupling effect between the coupling displacements of a point on the middle line of beam and large overall motion is presented. The 'coupling matrix library' and Jourdain's variation principle and single direction recursive formulation method are used to establish the general coupling dynamical equations of flexible multibody system. Two typical examples show the coupling effect between coupling displacements and large overall motion on the dynamics of flexible multibody system consisting of beams.展开更多
In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface h...In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface hardened 65 Mn steel were analyzed.The martensite transition transformation of the temperature of the laminar plasma-hardened 65 ferrite Mn steel was determined by a thermal-solid coupling model.Based on the orthogonal experimental results,the optimal hardening parameters were confirmed.The scanning velocity,quenching distance and arc current are 130 mm/min,50 mm and 120 A,respectively.The pearlites and ferrites are transformed into martensites in the hardened zone,while the ratio of martensite in the heataffected zone decreases with the increase in the hardening depth.Compared to the untreated 65Mn steel,the average hardness increases from 220 HV_(0.2)to 920 HV_(0.2)in the hardened zone and the corresponding absorbed power increases from 118.7 J to 175.5 J.At the same time,the average coefficient of friction(COF)decreases from 0.763 to 0.546,and the wear rate decreases from 5.39×10^(-6)mm^(3)/(N·m)to 2.95×10^(-6)mm^(3)/(N·m),indicating that the wear resistance of 65Mn steel could be significantly improved by using laminar surface hardening.With the same hardening parameters,the depth and width of the hardened zone predicted by the thermal-solid coupling model are 1.85 mm and 11.20 mm,respectively,which are in accordance with the experimental results;depth is 1.83 mm and width is 11.15 mm.In addition,the predicted hardness distributions of the simulation model are in accordance with the experimental results.These results indicate that the simulation model could effectively predict the microstructure characteristics of 65 Mn steel.展开更多
The arresting process of carrier-based aircraft is widely recognized as a challenging task,characterized by the highest accident rate among all carrier-based aircraft operations.Dynamic simulation plays a crucial role...The arresting process of carrier-based aircraft is widely recognized as a challenging task,characterized by the highest accident rate among all carrier-based aircraft operations.Dynamic simulation plays a crucial role in assessing the intricate responses of the arresting process,favoring the design of carrier-based aircraft.An efficient and accurate rigid-flexible coupling model for analyzing the dynamic response of the arresting process is proposed.By combining the dynamic characteristics of airframe,landing gear,arresting hook and arresting gear system,the rigid-flexible coupling dynamic model is established to reflect the relative motion of the coupling parts and arresting load.The dynamic model is verified through simulations of landing gear landing drops and by comparing the arresting simulation results with corresponding data in the US military standard.Additionally,simulations of the arresting process under different off-center distance and aircraft yaw angle are conducted to obtain the dynamic response of the aircraft during the arresting process.The result indicates that the rigid-flexible coupling dynamic model proposed is effective for analyzing the arresting dynamics response of carrier-based aircraft.The axial force of the arresting cable on both sides of the hook engagement point,pitch and yaw angle of aircraft are inconsistent under yaw and off-center arresting.The analysis method and obtained results provide valuable references for assessing the dynamic responses of carrier-based aircraft during arresting process and offer valuable in-sights in the design of carrier-based aircraft.展开更多
The aging characteristics of lithium-ion battery(LIB)under fast charging is investigated based on an electrochemical-thermal-mechanical(ETM)coupling model.Firstly,the ETM coupling model is established by COMSOL Multip...The aging characteristics of lithium-ion battery(LIB)under fast charging is investigated based on an electrochemical-thermal-mechanical(ETM)coupling model.Firstly,the ETM coupling model is established by COMSOL Multiphysics.Subsequently,a long cycle test was conducted to explore the aging characteristics of LIB.Specifically,the effects of charging(C)rate and cycle number on battery aging are analyzed in terms of nonuniform distribution of solid electrolyte interface(SEI),SEI formation,thermal stability and stress characteristics.The results indicate that the increases in C rate and cycling led to an increase in the degree of nonuniform distribution of SEI,and thus a consequent increase in the capacity loss due to the SEI formation.Meanwhile,the increases in C rate and cycle number also led to an increase in the heat generation and a decrease in the heat dissipation rate of the battery,respectively,which result in a decrease in the thermal stability of the electrode materials.In addition,the von Mises stress of the positive electrode material is higher than that of the negative electrode material as the cycling proceeds,with the positive electrode material exhibiting tensile deformation and the negative electrode material exhibiting compressive deformation.The available lithium ion concentration of the positive electrode is lower than that of the negative electrode,proving that the tensile-type fracture occurring in the positive material under long cycling dominated the capacity loss process.The aforementioned studies are helpful for researchers to further explore the aging behavior of LIB under fast charging and take corresponding preventive measures.展开更多
During high-speed flight,both thermal and mechani-cal loads can degrade the electrical performance of the antenna-radome system,which can subsequently affect the performance of the guidance system.This paper presents ...During high-speed flight,both thermal and mechani-cal loads can degrade the electrical performance of the antenna-radome system,which can subsequently affect the performance of the guidance system.This paper presents a method for evalu-ating the electrical performance of the radome when subjected to thermo-mechanical-electrical(TME)coupling.The method involves establishing a TME coupling model(TME-CM)based on the TME sharing mesh model(TME-SMM)generated by the tetrahedral mesh partitioning of the radome structure.The effects of dielectric temperature drift and structural deformation on the radome’s electrical performance are also considered.Firstly,the temperature field of the radome is obtained by tran-sient thermal analysis while the deformation field of the radome is obtained by static analysis.Subsequently,the dielectric varia-tion and structural deformation of the radome are accurately incorporated into the electrical simulation model based on the TME-SMM.The three-dimensional(3D)ray tracing method with the aperture integration technique is used to calculate the radome’s electrical performance.A representative example is provided to illustrate the superiority and necessity of the pro-posed method.This is achieved by calculating and analyzing the changes in the radome’s electrical performance over time dur-ing high-speed flight.展开更多
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.
文摘High performance electromechanical equipment is widely used in various fields, such as national defense, industry and so on [ 1]. In addition, the technical level of high performance electromechanical equipment is the embodiment of the national level of science and technology.
基金supported by the National Natural Science Foundation of China(No.62173281)the Natural Science Foundation of Sichuan Province(No.23ZDYF0734 and No.2023NSFSC1436)the Fund of Robot Technology Used for Special Environment Key Laboratory of Sichuan Province(No.18kftk03).
文摘Monitoring various internal parameters plays a core role in ensuring the safety of lithium-ion batteries in power supply applications.It also influences the sustainability effect and online state of charge prediction.An improved multiple feature-electrochemical thermal coupling modeling method is proposed considering low-temperature performance degradation for the complete characteristic expression of multi-dimensional information.This is to obtain the parameter influence mechanism with a multi-variable coupling relationship.An optimized decoupled deviation strategy is constructed for accurate state of charge prediction with real-time correction of time-varying current and temperature effects.The innovative decoupling method is combined with the functional relationships of state of charge and open-circuit voltage to capture energy management ef-fectively.Then,an adaptive equivalent-prediction model is constructed using the state-space equation and iterative feedback correction,making the proposed model adaptive to fractional calculation.The maximum state of charge estimation errors of the proposed method are 4.57% and 0.223% under the Beijing bus dynamic stress test and dynamic stress test conditions,respectively.The improved multiple feature-electrochemical thermal coupling modeling realizes the effective correction of the current and temperature variations with noise influencing coefficient,and provides an efficient state of charge prediction method adaptive to complex conditions.
基金supported by National Key R&D Program of China(Grant No.2021YFB2601200)Open Fund of National Engineering Research Center of Highway Maintenance Technology(Changsha University of Science&Technology)(No.kfj230207).
文摘The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and discrete element method(DEM)was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack.The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road.Finally,an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress,vertical shear stress,and vertical compressive stress.The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface,while the longitudinal development of TD crack has minimal impact.This phenomenon may result in more severe fatigue failure on the middle surface.With the vertical and longitudinal development of TD crack,the vertical shear stress and compressive stress show obvious"two-stage"characteristics.When the crack's vertical length reaches 40 mm,there is a sharp increase in stress on the upper surface.As the crack continues to propagate vertically,the growth of stress on the upper surface becomes negligible,while the stress in the middle and lower layers increased significantly.Conversely,for longitudinal development of TD crack,any changes in stress are insignificant when their length is less than 180 mm;however,as they continue to develop longitudinally beyond this threshold,there is a sharp increase in stress levels.These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.
基金supported by the National Natural Science Foundation of China(Grant No.52174117)the Universitylocal Government Scientific and Technical Cooperation Cultivation Project of Ordos Institute-LNTU(Grant No.YJY-XD-2024-A-009)+2 种基金the Basic Scientific Research Project of Liaoning Provincial Department of Education(Grant No.JYTZD2023073)the Liaoning Revitalization Talents Program(XLYC2203139)the Liaoning Provincial Natural Science Foundation Program(Excellent Youth Fund)(Grant No.2024JH3/10200043).
文摘The utilization of coalbed methane(CBM)cannot only alleviate the energy crisis,but also reduce greenhouse gas emissions.Gas injection is an effective method to enhance CBM recovery.Compared to single-gas injection,the injection of CO_(2)/N_(2) mixtures can balance the sharp decline in permeability caused by pure CO_(2) and the premature breakthrough by pure N_(2).In this study,a more comprehensive thermo-hydro-mechanical(THM)coupled mathematical model was developed,incorporating processes such as ternary gas non-isothermal adsorption,gas dissolution in water,gas-water two-phase flow,energy exchange,and coal deformation.After experimental validation,the model was applied to simulate the entire process of gas mixtures for enhanced CBM recovery(GM-ECBM).Results indicate that the permeability near the production well(Pw)initially decreases due to increased effective stress,then increases as a result of CH_(4) desorption.Near the injection well(Iw),the permeability first increases due to reduced effective stress and later stabilizes under the combined effects of effective stress and CO_(2)/N_(2) adsorption.The initial CH_(4) pressure and coal seam permeability have the most significant impact on CH_(4) production,while the coal seam permeability and temperature significantly affect CO_(2)/N_(2) injection.As the coal seam permeability increases,the optimal CO_(2)/N_(2) ratio also increases accordingly.These findings provide important theoretical guidance for improving GM-ECBM efficiency in coal seams with varying permeabilities.
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.
文摘Oxidative coupling of methane(OCM)is a catalytic partial oxidation process that directly converts methane into C_(2) products.For this high temperature reaction,understanding the radical behavior through experimental investigation is important in correlating the catalytic activity and the products.In this work,a spatial resolution online mass spectrometry(MS)system was developed and applied to a Mn-Na_(2)WO_(4)/SiO_(2) catalyzed OCM system.In addition to the residue gas analysis,the system obtained the distribution information of the reactants and products in the reactor.At various setting temperatures,all species online MS signals were collected at different positions,mapping the reaction activity covering parameters including temperature,time and space.The distribution behavior of the catalytic activity,selectivity,and apparent activation energy were kinetically analyzed.Selectivity and additional carbon balance analysis strongly supported the radical coupling model of OCM and indicated that after the catalytic bed layer,there is a significant length in the reactor(>2 mm)filled with radicals.Based on the result,a designed new method by tuning the temperature field in the reactor was found effectively to improve the catalytic activity,especially the C_(2) yield from 702 to 773℃.
基金supported by the National Natural Science Foundation of China(Grant No.11872236).
文摘The largely bending bilayer electrode model battery has been widely used to measure the mechanical properties of composite electrode materials.The assumption used in the method that lithium is uniformly distributed in the active layer lacks quantitative evaluation,and the uniformity of concentration distribution is crucial for accurate in-situ measurements of concentration-related material properties and stress in bilayer electrodes.Therefore,this paper proposes a mechanical-electrochemical coupled model to study the lithium concentration distribution in the active layer during lithiation.This model includes lithium concentration diffusion and active layer deformation.By comparing experimental and simulated curvature evolution of the active layer during lithiation and delithiation,the reliability of this simulation model is verified.We then derive the precise concentration distribution inside the active layer and suggest using relative error to quantitatively evaluate the uniformity of lithium concentration in the active layer.Results show that a low relative error in lithium concentration can be achieved in the middle region of the active layer.Additionally,the effects of different rates and geometric parameters on the lithium concentration distribution in the active layer are discussed.Results indicate that reduced rates,thinner active layers,shorter active layer lengths,and increased spacing between the working and counter electrodes can lead to a more uniform distribution of lithium concentration in the active layer.These insights help improve experimental methods and equipment,promoting uniform distribution of lithium in the active layer and enhancing measurement accuracy.
基金Humanities and Social Sciences Fund of Ministry of Education of China,No.24YJA630097National Natural Science Foundation of China,No.42471304。
文摘The uneven distribution of medical resources has led to increasingly frequent patient mobility;however, the interaction between this phenomenon and the healthcare supply-demand relationship remains underexplored. The present study constructed the 2023Cross-City Patient Mobility Network in China using one million patient mobility data records obtained from online healthcare platforms. We applied urban network analysis to uncover mobility patterns and used the coupling coordination degree model to assess healthcare supply-demand relationships before and after patient mobility. Explainable machine learning further revealed the impact of supply-demand coupling on patient mobility. The results indicated the following: Patient mobility followed administrative boundaries, although megacities serve areas beyond provincial borders;The scale of healthcare supply and demand displayed a multi-centric spatial pattern with a general decline from east to west, and these characteristics of demand distribution were further solidified by patient mobility;Cities with low supply-demand coupling and undersupply experienced patient outflows, while cities with high coupling and oversupply attracted them. In turn, patient mobility helped balance healthcare supply and demand, optimising the coupling relationship across cities. Thus, this research not only provides a methodological reference for understanding the interaction between patient mobility and healthcare systems but also offers empirical insights for public health policy.
文摘In view of the problem that a single modeling method cannot predict the distribution of microfacies, a new idea of coupling modeling method to comprehensively predict the distribution of sedimentary microfacies was proposed, breaking the tradition that different sedimentary microfacies used the same modeling method in the past. Because different sedimentary microfacies have different distribution characteristics and geometric shapes, it is more accurate to select different simulation methods for prediction. In this paper, the coupling modeling method was to establish the distribution of sedimentary microfacies with simple geometry through the point indicating process simulation, and then predict the microfacies with complex spatial distribution through the sequential indicator simulation method. Taking the DC block of Bohai basin as an example, a high-precision reservoir sedimentary microfacies model was established by the above coupling modeling method, and the model verification results showed that the sedimentary microfacies model had a high consistency with the underground. The coupling microfacies modeling method had higher accuracy and reliability than the traditional modeling method, which provided a new idea for the prediction of sedimentary microfacies.
基金Supported by National Natural Science Foundation of China(Grant No.51375424)
文摘The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simul- taneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through intro- ducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the cou- pled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural defor- mation movement＇s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment ofdynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.
文摘Pyrotechnic devices are widely used in the aerospace and defense industries.However,these devices generate high-frequency and high-amplitude shock responses during their use,compromising safe operation of the system.In this paper,the application of a thin-walled circular tube as the energy absorber in pyrotechnic devices is investigated.To accurately predict the shock load and the buffer performance of the thin-walled circular tube,a coupled model connecting the energetic material combustion and finite element simulation is established.The validity of the coupled model is verified by comparing with experiments.Then,the collapse mechanism of the thin-walled circular tube is studied,and the influence of multiple structural parameters on its buffer performance is analyzed.The results show that the thin-walled circular tube effectively reduces the shock overload.The maximum shock overload reduced from 572612g to 11204g in the studied case.The structural parameters of the thin-walled circular tube mainly affect the deformation process and the maximum shock overload.The order of importance of structural parameters to the maximum shock overload is determined,among which the wall thickness has the most significant effect.
基金co-supported by the National Natural Science Foundation of China (Nos. 61374145 and U1333131)
文摘Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation of this system. The dynamic model of the heavy-equipment airdrop is based on the Lagrange analytical mechanics, which has all the degrees of freedom and can accurately pinpoint the real-time coordinates and attitude of the carrier with its cargo. Unfavorable conditions accounted in the factors＇ models, including aircraft malfunctions and adverse environments, are established from a man-machine-environment perspective. Subsequently, a virtual simulation system for the safety research of the multi-factor coupling heavy-equipment airdrop is developed through MATLAB/Simulink, C language and Flightgear software. To verify the veracity of the theory, the verification model is built based on dynamic software ADAMS. Finally, the emulation is put to the test with the input of realistic accident variables to ascertain its feasibility and validity of this method.
基金Supported by Open Fund of National Key Laboratory of Power Grid Safety(No.XTB51202301386).
文摘Energy storage batteries can smooth the volatility of renewable energy sources.The operating conditions during power grid integration of renewable energy can affect the performance and failure risk of battery energy storage system(BESS).However,the current modeling of grid-connected BESS is overly simplistic,typically only considering state of charge(SOC)and power constraints.Detailed lithium(Li)-ion battery cell models are computationally intensive and impractical for real-time applications and may not be suitable for power grid operating conditions.Additionally,there is a lack of real-time batteries risk assessment frameworks.To address these issues,in this study,we establish a thermal-electric-performance(TEP)coupling model based on a multitime scale BESS model,incorporating the electrical and thermal characteristics of Li-ion batteries along with their performance degradation to achieve detailed simulation of grid-connected BESS.Additionally,considering the operating characteristics of energy storage batteries and electrical and thermal abuse factors,we developed a battery pack operational riskmodel,which takes into account SOCand charge-discharge rate(Cr),using amodified failure rate to represent the BESS risk.By integrating detailed simulation of energy storage with predictive failure risk analysis,we obtained a detailed model for BESS risk analysis.This model offers a multi-time scale integrated simulation that spans month-level energy storage simulation times,day-level performance degradation,minutescale failure rate,and second-level BESS characteristics.It offers a critical tool for the study of BESS.Finally,the performance and risk of energy storage batteries under three scenarios—microgrid energy storage,wind power smoothing,and power grid failure response—are simulated,achieving a real-time state-dependent operational risk analysis of the BESS.
基金the National Natural Science Foundation of China(No.19832040)
文摘Based on the deformation theory of elastic beams, the coupling effect between the coupling displacements of a point on the middle line of beam and large overall motion is presented. The 'coupling matrix library' and Jourdain's variation principle and single direction recursive formulation method are used to establish the general coupling dynamical equations of flexible multibody system. Two typical examples show the coupling effect between coupling displacements and large overall motion on the dynamics of flexible multibody system consisting of beams.
基金appreciate the support of the Key Laboratory of Mechanical Structure Optimization&Material Application Technology of Luzhou(No.SCHYZSA-2022-02)the Scientific Research and Innovation Team Program of Sichuan University of Science and Technology(No.SUSE652A004)+1 种基金the Key Laboratory of Intelligent Manufacturing of Construction Machinery Project(No.IMCM202103)the Panzhihua Key Laboratory of Advanced Manufacturing Technology Open Fund Project(No.2022XJZD01)。
文摘In the present work,the laminar plasma surface hardening method is employed to enhance the service life of metal components fabricated from 65 Mn steel.The mechanical and wear behaviors of the laminar plasma surface hardened 65 Mn steel were analyzed.The martensite transition transformation of the temperature of the laminar plasma-hardened 65 ferrite Mn steel was determined by a thermal-solid coupling model.Based on the orthogonal experimental results,the optimal hardening parameters were confirmed.The scanning velocity,quenching distance and arc current are 130 mm/min,50 mm and 120 A,respectively.The pearlites and ferrites are transformed into martensites in the hardened zone,while the ratio of martensite in the heataffected zone decreases with the increase in the hardening depth.Compared to the untreated 65Mn steel,the average hardness increases from 220 HV_(0.2)to 920 HV_(0.2)in the hardened zone and the corresponding absorbed power increases from 118.7 J to 175.5 J.At the same time,the average coefficient of friction(COF)decreases from 0.763 to 0.546,and the wear rate decreases from 5.39×10^(-6)mm^(3)/(N·m)to 2.95×10^(-6)mm^(3)/(N·m),indicating that the wear resistance of 65Mn steel could be significantly improved by using laminar surface hardening.With the same hardening parameters,the depth and width of the hardened zone predicted by the thermal-solid coupling model are 1.85 mm and 11.20 mm,respectively,which are in accordance with the experimental results;depth is 1.83 mm and width is 11.15 mm.In addition,the predicted hardness distributions of the simulation model are in accordance with the experimental results.These results indicate that the simulation model could effectively predict the microstructure characteristics of 65 Mn steel.
基金This study was co-supported by the National Natural Science Foundation of China(No.T2288101)the National Key Research and Development Project,China(No.2020YFC1512500).
文摘The arresting process of carrier-based aircraft is widely recognized as a challenging task,characterized by the highest accident rate among all carrier-based aircraft operations.Dynamic simulation plays a crucial role in assessing the intricate responses of the arresting process,favoring the design of carrier-based aircraft.An efficient and accurate rigid-flexible coupling model for analyzing the dynamic response of the arresting process is proposed.By combining the dynamic characteristics of airframe,landing gear,arresting hook and arresting gear system,the rigid-flexible coupling dynamic model is established to reflect the relative motion of the coupling parts and arresting load.The dynamic model is verified through simulations of landing gear landing drops and by comparing the arresting simulation results with corresponding data in the US military standard.Additionally,simulations of the arresting process under different off-center distance and aircraft yaw angle are conducted to obtain the dynamic response of the aircraft during the arresting process.The result indicates that the rigid-flexible coupling dynamic model proposed is effective for analyzing the arresting dynamics response of carrier-based aircraft.The axial force of the arresting cable on both sides of the hook engagement point,pitch and yaw angle of aircraft are inconsistent under yaw and off-center arresting.The analysis method and obtained results provide valuable references for assessing the dynamic responses of carrier-based aircraft during arresting process and offer valuable in-sights in the design of carrier-based aircraft.
基金funded by the National Natural Science Foundation of China(Grant No.12272217)。
文摘The aging characteristics of lithium-ion battery(LIB)under fast charging is investigated based on an electrochemical-thermal-mechanical(ETM)coupling model.Firstly,the ETM coupling model is established by COMSOL Multiphysics.Subsequently,a long cycle test was conducted to explore the aging characteristics of LIB.Specifically,the effects of charging(C)rate and cycle number on battery aging are analyzed in terms of nonuniform distribution of solid electrolyte interface(SEI),SEI formation,thermal stability and stress characteristics.The results indicate that the increases in C rate and cycling led to an increase in the degree of nonuniform distribution of SEI,and thus a consequent increase in the capacity loss due to the SEI formation.Meanwhile,the increases in C rate and cycle number also led to an increase in the heat generation and a decrease in the heat dissipation rate of the battery,respectively,which result in a decrease in the thermal stability of the electrode materials.In addition,the von Mises stress of the positive electrode material is higher than that of the negative electrode material as the cycling proceeds,with the positive electrode material exhibiting tensile deformation and the negative electrode material exhibiting compressive deformation.The available lithium ion concentration of the positive electrode is lower than that of the negative electrode,proving that the tensile-type fracture occurring in the positive material under long cycling dominated the capacity loss process.The aforementioned studies are helpful for researchers to further explore the aging behavior of LIB under fast charging and take corresponding preventive measures.
文摘During high-speed flight,both thermal and mechani-cal loads can degrade the electrical performance of the antenna-radome system,which can subsequently affect the performance of the guidance system.This paper presents a method for evalu-ating the electrical performance of the radome when subjected to thermo-mechanical-electrical(TME)coupling.The method involves establishing a TME coupling model(TME-CM)based on the TME sharing mesh model(TME-SMM)generated by the tetrahedral mesh partitioning of the radome structure.The effects of dielectric temperature drift and structural deformation on the radome’s electrical performance are also considered.Firstly,the temperature field of the radome is obtained by tran-sient thermal analysis while the deformation field of the radome is obtained by static analysis.Subsequently,the dielectric varia-tion and structural deformation of the radome are accurately incorporated into the electrical simulation model based on the TME-SMM.The three-dimensional(3D)ray tracing method with the aperture integration technique is used to calculate the radome’s electrical performance.A representative example is provided to illustrate the superiority and necessity of the pro-posed method.This is achieved by calculating and analyzing the changes in the radome’s electrical performance over time dur-ing high-speed flight.
